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Sample records for head-up tilt test-induced

  1. 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...

  2. The impact of gravity during head-up tilt

    DEFF Research Database (Denmark)

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

    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...

  3. The impact of gravity during head-up tilt

    DEFF Research Database (Denmark)

    Olufsen, Mette; Smith, Brittany; Mehlsen, Jesper

    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...

  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, pvasovagal syncope children. There was no significant difference in the time to positive response, at different tilt angles during the head-up tilt test 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. Postural tachycardia syndrome with asystole on head-up tilt.

    Science.gov (United States)

    Alshekhlee, Amer; Guerch, Meziane; Ridha, Faisal; Mcneeley, Kevin; Chelimsky, Thomas C

    2008-02-01

    Enhanced sympathetic activity causes an exaggerated heart rate response to standing in the postural tachycardia syndrome (POTS). All patients describe symptoms of orthostatic intolerance such as dizziness, blurred vision, shortness of breath, palpitations, tremulousness, chest discomfort, headache, lightheadedness and nausea, but only one third suffer loss of consciousness. We report four patients with POTS, who had long ventricular pauses (i.e. asystole) and syncope during head-up tilt test. This suggests that a subset of patients with POTS can have a surge in parasympathetic outflow that precedes vasovagal syncope.

  6. A Cardiovascular Mathematical Model of Graded Head-Up Tilt

    Science.gov (United States)

    Lim, Einly; Chan, Gregory S. H.; Dokos, Socrates; Ng, Siew C.; Latif, Lydia A.; Vandenberghe, Stijn; Karunanithi, Mohan; Lovell, Nigel H.

    2013-01-01

    A lumped parameter model of the cardiovascular system has been developed and optimized using experimental data obtained from 13 healthy subjects during graded head-up tilt (HUT) from the supine position to . The model includes descriptions of the left and right heart, direct ventricular interaction through the septum and pericardium, the systemic and pulmonary circulations, nonlinear pressure volume relationship of the lower body compartment, arterial and cardiopulmonary baroreceptors, as well as autoregulatory mechanisms. A number of important features, including the separate effects of arterial and cardiopulmonary baroreflexes, and autoregulation in the lower body, as well as diastolic ventricular interaction through the pericardium have been included and tested for their significance. Furthermore, the individual effect of parameter associated with heart failure, including LV and RV contractility, baseline systemic vascular resistance, pulmonary vascular resistance, total blood volume, LV diastolic stiffness and reflex gain on HUT response have also been investigated. Our fitted model compares favorably with our experimental measurements and published literature at a range of tilt angles, in terms of both global and regional hemodynamic variables. Compared to the normal condition, a simulated congestive heart failure condition produced a blunted response to HUT with regards to the percentage changes in cardiac output, stroke volume, end diastolic volume and effector response (i.e., heart contractility, venous unstressed volume, systemic vascular resistance and heart rate) with progressive tilting. PMID:24204817

  7. A cardiovascular mathematical model of graded head-up tilt.

    Directory of Open Access Journals (Sweden)

    Einly Lim

    Full Text Available A lumped parameter model of the cardiovascular system has been developed and optimized using experimental data obtained from 13 healthy subjects during graded head-up tilt (HUT from the supine position to [Formula: see text]. The model includes descriptions of the left and right heart, direct ventricular interaction through the septum and pericardium, the systemic and pulmonary circulations, nonlinear pressure volume relationship of the lower body compartment, arterial and cardiopulmonary baroreceptors, as well as autoregulatory mechanisms. A number of important features, including the separate effects of arterial and cardiopulmonary baroreflexes, and autoregulation in the lower body, as well as diastolic ventricular interaction through the pericardium have been included and tested for their significance. Furthermore, the individual effect of parameter associated with heart failure, including LV and RV contractility, baseline systemic vascular resistance, pulmonary vascular resistance, total blood volume, LV diastolic stiffness and reflex gain on HUT response have also been investigated. Our fitted model compares favorably with our experimental measurements and published literature at a range of tilt angles, in terms of both global and regional hemodynamic variables. Compared to the normal condition, a simulated congestive heart failure condition produced a blunted response to HUT with regards to the percentage changes in cardiac output, stroke volume, end diastolic volume and effector response (i.e., heart contractility, venous unstressed volume, systemic vascular resistance and heart rate with progressive tilting.

  8. Assessment of cardiovascular regulation during head-up tilt and suspension in swimmers.

    Science.gov (United States)

    Ifuku, Hirotoshi; Shiraishi, Yumiko

    2004-01-01

    The purpose of the present study was to compare cardiovascular responses in competitive swimmers with those in track and field (T and F) athletes during head-up tilt with engagement of the antigravity muscles in the lower extremities and during passive head-up suspension without the engagement of the antigravity muscles. Blood pressure and heart rate during head-up tilt were compared among T and F athletes (N = 11), competitive swimmers (N = 15), and untrained subjects (N = 11). Moreover, stroke volume, cardiac output, and total peripheral resistance during head-up tilt and head-up suspension were also measured in T and F athletes and competitive swimmers. The heart rate increased significantly in all subject groups during head-up tilt; however, the MBP decreased in untrained subjects but did not change significantly in T and F athletes or competitive swimmers. Moreover, the DBP did not change significantly in untrained subjects or T and F athletes but increased significantly in swimmers. As with the head-up tilt, during the head-up suspension, the SBP decreased significantly and the heart rate increased significantly in both types of athletes, though the MBP decreased significantly. The ratios of decrease in stroke volume and cardiac output were significantly larger in swimmers than in T and F athletes during head-up tilt, but no significant difference was noted during head-up suspension. In T and F athletes, the ratios of decrease in stroke volume and cardiac output were significantly larger during head-up suspension than during head-up tilt, but no significant difference was noted in swimmers. The action of the antigravity muscles on cardiovascular regulation during upright standing is smaller in competitive swimmers than in T and F athletes.

  9. Head-up tilt test with clomipramine challenge in vasovagal syndrome--a new tilt testing protocol

    National Research Council Canada - National Science Library

    Theodorakis, G N; Livanis, E G; Leftheriotis, D; Flevari, P; Markianos, M; Kremastinos, D Th

    2003-01-01

    The aim of the study was to randomly compare clomipramine, used as a challenge-agent during head-up tilt test, with isoproterenol, used in the conventional test, in patients with vasovagal syndrome...

  10. Relationship between blood pressure and heart-rate variability during graded head-up tilt.

    Science.gov (United States)

    Yokoi, Y; Aoki, K

    1999-02-01

    To investigate the relationship between change in blood pressure and autonomic nerve activity, two types of head-up tilt experiments were performed. One was a 30 degrees, 45 degrees, 60 degrees, and 90 degrees graded tilt-up, in which tilt angles were changed at 6-min intervals and 5 min were spent at each angle. The other was a 10-min lasting head-up tilt at 60 degrees. Electrocardiogram (ECG) and blood pressure (Finapres) of 18 healthy non-smoking subjects (9 men, 9 women) were recorded during the experiments. Heart-rate variability was examined by general spectral analysis (GSA). The high-frequency/total-area ratio (HF/TO) showed a decrease as the tilt angle increased. Compared with the values at the 0 degrees position, these changes were statistically significant (P < 0.05). The low-frequency/HF ratio (LF/HF) showed a significant (P < 0.05) difference between 0 degrees and 90 degrees, and between 30 degrees and 90 degrees. Some of the subjects could not maintain their blood pressure during either of the head-up tilt experiments, and they showed only a slight change in HF/TO and LF/HF. This result confirmed that immediate responses to head-up tilt reflect autonomic nerve activity. Hence, changes in the frequency components were found to be an index of autonomic nerve activity, and they explained the individual differences observed in the ability to control blood pressure during a transition to upright posture.

  11. Impaired cerebral autoregulation during head up tilt in patients with severe brain injury

    DEFF Research Database (Denmark)

    Riberholt, Christian Gunge; Olesen, Niels Damkjær; Thing, Mira

    2016-01-01

    mean velocity and estimated cerebral perfusion pressure. Patients with acquired brain injury presented an increase in mean flow index during head-up tilt indicating impaired autoregulation (P frequency domain revealed lower magnitudes of ∼0.......1 Hz spectral power in patients compared to healthy controls suggesting baroreflex dysfunction. In conclusion, patients with severe acquired brain injury and orthostatic intolerance during head-up tilt have impaired cerebral autoregulation more than one month after brain injury.......Early mobilization is of importance for improving long-term outcome for patients after severe acquired brain injury. A limiting factor for early mobilization by head-up tilt is orthostatic intolerance. The purpose of the present study was to examine cerebral autoregulation in patients with severe...

  12. Cholinergic induced mesenteric vasorelaxation in response to head-up tilt

    DEFF Research Database (Denmark)

    Perko, M J; Madsen, P; Perko, G

    1999-01-01

    resistance as expressed by analogous elevations in the diastolic blood velocity (to 62 +/- 9 vs. 56 +/- 7 cm s-1 with placebo). Throughout the normotensive and hypotensive phases of head-up tilt, cholinergic blockade reduced mesenteric artery mean blood velocity by 39 and 42%, respectively, corresponding......Central hypovolaemia induced by head-up tilt evokes a reduction in superior mesenteric artery resistance resulting in maintenance of regional blood flow. Mechanisms of importance for this response are not known, but a parasympathetic contribution could be expected. To evaluate this hypothesis......, superior mesenteric artery blood flow and resistance were evaluated by duplex ultrasound in eight healthy volunteers during postprandial head-up tilt with and without cholinergic blockade. During supine rest, cholinergic blockade did not influence the postprandial reduction in peripheral mesenteric artery...

  13. Impaired Cerebral Autoregulation during Head Up Tilt in Patients with Severe Brain Injury.

    Directory of Open Access Journals (Sweden)

    Christian Gunge Riberholt

    Full Text Available Early mobilization is of importance for improving long-term outcome for patients after severe acquired brain injury. A limiting factor for early mobilization by head-up tilt is orthostatic intolerance. The purpose of the present study was to examine cerebral autoregulation in patients with severe acquired brain injury and a low level of consciousness. Fourteen patients with severe acquired brain injury and orthostatic intolerance and fifteen healthy volunteers were enrolled. Blood pressure was evaluated by pulse contour analysis, heart rate and RR-intervals were determined by electrocardiography, middle cerebral artery velocity was evaluated by transcranial Doppler, and near-infrared spectroscopy determined frontal lobe oxygenation in the supine position and during head-up tilt. Cerebral autoregulation was evaluated as the mean flow index calculated as the ratio between middle cerebral artery mean velocity and estimated cerebral perfusion pressure. Patients with acquired brain injury presented an increase in mean flow index during head-up tilt indicating impaired autoregulation (P < 0.001. Spectral analysis of heart rate variability in the frequency domain revealed lower magnitudes of ~0.1 Hz spectral power in patients compared to healthy controls suggesting baroreflex dysfunction. In conclusion, patients with severe acquired brain injury and orthostatic intolerance during head-up tilt have impaired cerebral autoregulation more than one month after brain injury.

  14. Mesenteric artery response to head-up tilt-induced central hypovolaemia and hypotension

    DEFF Research Database (Denmark)

    Perko, M J; Madsen, P; Perko, Grazyna

    1997-01-01

    Superior mesenteric artery (SMA) blood flow and impedance were evaluated by duplex ultrasound during head-up tilt (HUT)-induced central hypovolaemia and hypotension in eight healthy volunteers. HUT induced a reduction in cardiac stroke volume from 88.8 +/- 6.3 to 64.7 +/- 6.3 ml (mean +/- SEM; P ...

  15. Effects of closed-loop stimulation vs. DDD pacing on haemodynamic variations and occurrence of syncope induced by head-up tilt test in older patients with refrac\\tory cardioinhibitory vasovagal syncope: the Tilt test-Induced REsponse in Closed-loop Stimulation multicentre, prospective, single blind, randomized study.

    Science.gov (United States)

    Palmisano, Pietro; Dell'Era, Gabriele; Russo, Vincenzo; Zaccaria, Maria; Mangia, Rolando; Bortnik, Miriam; De Vecchi, Federica; Giubertoni, Ailia; Patti, Fabiana; Magnani, Andrea; Nigro, Gerardo; Rago, Anna; Occhetta, Eraldo; Accogli, Michele

    2017-04-12

    Closed-loop stimulation (CLS) seemed promising in preventing the recurrence of vasovagal syncope (VVS) in patients with a cardioinhibitory response to head-up tilt test (HUTT) compared with conventional pacing. We hypothesized that the better results of this algorithm are due to its quick reaction in high-rate pacing delivered in the early phase of vasovagal reflex, which increase the cardiac output and the blood pressure preventing loss of consciousness. This prospective, randomized, single-blind, multicentre study was designed as an intra-patient comparison and enrolled 30 patients (age 62.2 ± 13.5 years, males 60.0%) with cardioinhibitory VVS, carrying a dual-chamber pacemaker incorporating CLS algorithm. Two HUTTs were performed one week apart: one during DDD-CLS 60-130/min pacing and the other during DDD 60/min pacing; patients were randomly and blindly assigned to two groups: in one the first HUTT was performed in DDD-CLS (n = 15), in the other in DDD (n = 15). Occurrence of syncope and haemodynamic variations induced by HUTT was recorded during the tests. Compared with DDD, DDD-CLS significantly reduced the occurrence of syncope induced by HUTT (30.0% vs. 76.7%; P DDD and DDD-CLS mode, DDD-CLS significantly delayed the onset of syncope during HUTT (from 20.8 ± 3.9 to 24.8 ± 0.9 min; P = 0.032). The maximum fall in systolic blood pressure recorded during HUTT was significantly lower in DDD-CLS compared with DDD (43.2 ± 30.3 vs. 65.1 ± 25.8 mmHg; P = 0.004). In patients with cardioinhibitory VVS, CLS reduces the occurrence of syncope induced by HUTT, compared with DDD pacing. When CLS is not able to abort the vasovagal reflex, it seems to delay the onset of syncope.

  16. Head-up tilt test with clomipramine challenge in vasovagal syndrome--a new tilt testing protocol.

    Science.gov (United States)

    Theodorakis, G N; Livanis, E G; Leftheriotis, D; Flevari, P; Markianos, M; Kremastinos, D Th

    2003-04-01

    The aim of the study was to randomly compare clomipramine, used as a challenge-agent during head-up tilt test, with isoproterenol, used in the conventional test, in patients with vasovagal syndrome. The serotonergic re-uptake inhibitor clomipramine was infused (5mg in 5min) at the start of head-up tilt test (Clom-HUT) in 126 patients (mean age 41+/-16 years) with positive history of recurrent neurocardiogenic syncope, and in 54 healthy control subjects (mean age 46+/-15 years). All subjects had also been tested with a conventional 60 degrees head-up tilt test (Con-HUT) for 30 min and, if negative, isoproterenol infusion was performed at the end of the test. The two tests were performed in a random order with a 24-h interval between them. Fifty-two of the 126 patients (41%) and two of the 54 controls had a positive response to Con-HUT. In the Clom-HUT the proportion of patients who experienced a positive response increased to 83% (105 subjects), while this happened only to four control subjects. The predictive accuracy of Clom-HUT increased compared to Con-HUT from 58 to 86%, respectively. The results indicate an increased responsiveness of central serotonergic neural system in subjects with vasovagal syndrome, the activation of which leads to sympathetic withdrawal. The use of clomipramine infusion during tilt test seems to improve considerably its diagnostic value.

  17. Brain and muscle oxygen saturation during head-up-tilt-induced central hypovolaemia in humans.

    Science.gov (United States)

    Madsen, P; Lyck, F; Pedersen, M; Olesen, H L; Nielsen, H; Secher, N H

    1995-09-01

    Near-infrared spectrophotometry-determined cerebral (ScO2) and muscle oxygen saturations (SmO2) were followed in 15 volunteers during passive 50 degrees head-up-tilt-induced central hypovolaemia, and in nine volunteers during ventilatory manoeuvres affecting arterial carbon dioxide tension. During head-up tilt, mean arterial pressure [MAP, 88 (77-118) to 97 (80-136) mmHg, median and range] and heart rate [HR; 66 (49-77) to 87 (42-132) beats min-1 P tilt-up. The ScO2 decreased, and SmO2 increased during hyperventilation, and ScO2 increased during breathing of 5% carbon dioxide. Rebreathing from a bag made SmO2 decrease and resulted in a biphasic ScO2 response: it first increased and subsequently decreased. Cardiovascular changes during tilt were not reflected in skin temperature. The ScO2 reflected the maintained autoregulation of cerebral blood flow until the perfusion pressure decreased markedly. In contrast, SmO2 mirrored muscle vasoconstriction early during tilt, and vasodilatation when pre-syncopal symptoms appeared.

  18. Head-up tilt rapidly compromises hemodynamics in healthy anesthetized swine.

    Science.gov (United States)

    Mlcek, M; Belohlavek, J; Huptych, M; Boucek, T; Belza, T; Lacko, S; Krupickova, P; Hrachovina, M; Popkova, M; Neuzil, P; Kittnar, O

    2015-01-01

    The aims were to explore the effect of head-up tilt (HUT) to 30 and 60 degrees on hemodynamics and tissue oxygenation in anesthetized healthy swine. The data serve as a reference for a study of resuscitation efficacy at HUT such as during transport. Nine healthy swine (49+/-4 kg) were anesthetized and multiple sensors including myocardial pressure-volume loops catheter, carotid flow probe, blood pressure catheters, near infrared spectroscopy (NIRS) tissue oximetry and mixed venous oximetry (SVO2) catheter were introduced and parameters continuously recorded. Experimental protocol consisted of baseline in supine position (15 min), 30 degrees HUT (15 min), recovery at supine position (15 min) and 60 degrees HUT (5 min). Vacuum mattress was used for body fixation during tilts. We found that 30 and 60 degrees inclination led to significant immediate reduction in hemodynamic and oximetry parameters. Mean arterial pressure (mm Hg) decreased from 98 at baseline to 53 and 39, respectively. Carotid blood flow dropped to 47 % and 22 % of baseline values, end diastolic volume to 49 % and 53 % and stroke volume to 47 % and 45 % of baseline. SVO2 and tissue oximetry decreased by 17 and 21 percentage points. The values are means. In conclusions, within minutes, both 30 and 60 degrees head-up tilting is poorly tolerated in anesthetized swine. Significant differences among individual animals exist.

  19. Different haemodynamic patterns in head-up tilt test on 400 paediatric cases with unexplained syncope.

    Science.gov (United States)

    Yozgat, Yilmaz; Karadeniz, Cem; Ozdemir, Rahmi; Doksoz, Onder; Kucuk, Mehmet; Karaarslan, Utku; Mese, Timur; Unal, Nurettin

    2015-06-01

    To assess haemodynamic patterns in head-up tilt testing on 400 paediatric cases with unexplained syncope. Medical records of 520 children who underwent head-up tilt testing in the preceding year were retrospectively evaluated, and 400 children, 264 (66%) girls and 136 (34%) boys, aged 12.6±2.6 years (median 13; range 5-18), with unexplained syncope were enrolled in the study. Age, sex, baseline heart rate, baseline blood pressure, frequency of symptoms, and/or fainting attacks were recorded. The test protocol consisted of 25 minutes of supine resting followed by 20 minutes of 70° upright positioning. Subjects were divided into nine groups according to their differing haemodynamic patterns. There were no statistically significant differences between the groups with regard to age, gender, baseline blood pressure, and frequency of syncope (p>0.05). The response was compatible with orthostatic intolerance in 28 cases (7.0%), postural orthostatic tachycardia syndrome in 24 cases (6.0%), asymptomatic postural orthostatic tachycardia syndrome in 26 cases (6.5%), orthostatic hypotension in seven cases (1.7%), vasovagal syncope in 38 cases (9.5%), and negative in 274 cases (69.2%). Vasovagal syncope response patterns were of type 3 in nine cases (2.2%), type 2A in 10 cases (2.5%), type 2B in two cases (0.5%), and type 1 (mixed) in 17 cases (4.25%). In the 400 paediatric cases with unexplained syncope, nine different haemodynamic response patterns to head-up tilt testing were discerned. Children with orthostatic intolerance syndromes are increasingly referred to hospitals because of difficulty in daily activities. Therefore, there is need for further clinical trials in these patient groups.

  20. Capillary Pressure Balance with Repeated Head-Up Tilt in Humans

    Science.gov (United States)

    Hinghofer-Szalkay, H. G.; Greenleaf, J. F.

    1995-01-01

    We measured blood density (BD). plasma density (PD) and hematocrit (Ht) during repeated 70 deg head-up tilt (HUT) consisting of a pre-drink period with two supine (P and P3) and two HUT (P2 and P4) phases of 45 min each. At the end of P4 test subjects (N=8) drank 10 ml/kg body weight of isotonic (290 mOsm/kg) sodium chloride (ISO) or hypotonic (drink treatment (P3, P5, P7), supine PV steadly decreased when compared to P1. Tilt-induced PV shifts ranged from 9.7 to 16.7% when compared to PV du. ring the respective previous Phases. After drinking, PV increased above CON values at the end of Phase 7 by 12.9% with ISO, and by 6.6% with HYP. Progressive hemoconcentration. occurred during non-drink supine; isotonic saline ingestion increased supine PV a control level but did not stop or reverse the decrease of upright hemoconcentration. Upright density values were not slowed with repeated upright tilting; decreased fluid loss occurred in consecutive upright periods. Upright capillary pressure balance was achieved with diminished plasma volume loss during repeated tilting.

  1. [Evaluation of psychological fear in children undergoing head-up tilt test].

    Science.gov (United States)

    Chu, Wei-Hong; Wu, Li-Jia; Wang, Cheng; Lin, Ping; Li, Fang; Zhu, Li-Ping; Ran, Jing; Zou, Run-Mei; Liu, De-Yu

    2014-03-01

    To investigate the effects of different tilt angles of head-up tilt test (HUTT) and different responses to HUTT on the psychological fear in children undergoing the test. HUTT was performed on children with unexplained syncope or pre-syncope (107 cases: 52 males and 55 females), aged 5.5-17.8 years (mean 12.0±2.8 years). All subjects were randomly assigned to undergo HUTT at an angle of 60°, 70° or 80°; the negative cases underwent sublingual nitroglycerin-provocation HUTT at the same tilt angle. The Wong-Baker Faces Pain Rating Scale was used for self-assessment of psychological fear in subjects during HUTT at the end point of the test. The positive rate, hemodynamic changes and distribution of response types showed no significant differences between children at tilt angles of 60°, 70° and 80° (P>0.05). The greater the tilt angle, the higher the degree of psychological fear in children undergoing the test, but there were no significant differences between them (P>0.05). The degree of psychological fear in children who showed a positive response to HUTT (n=76) was significantly higher than that in children who showed a negative response (n=31) (Ppsychological fear in children undergoing the test, and the degree of psychological fear increases in children tested at tilt angles from 60° to 80°, but the differences have no statistical significance. A positive response to HUTT can significantly increase the psychological fear in children.

  2. Calf Venous Compliance in Supine Posture Equals that Measured with Head-up Tilt

    Science.gov (United States)

    Watenpaugh, Donald E.; Ballard, R. E.; Breit, G. A.; Bernauer, E. M.; Blomqvist, C. G.; Hargens, Alan R.

    1995-01-01

    Calf venous compliance is measured conventionally with venous occlusion, where compliance equals calf volume elevation per mmHg thigh occlusion pressure in relaxed legs of supine subjects. Compliance may also be measured during stepwise head-up tilt (HUT) as calf volume elevation per mmHg gravitational venous pressure elevation produced by HUT. Although HUT on a tilt table with a footplate activates calf muscles which could reduce compliance, this muscle activation is relatively small (less than or = 10% of maximal voluntary levels). Therefore, we hypothesized that calf compliance measured with HUT equals that measured with conventional supine venous occlusion. The venous occlusion protocol consisted of 20, 40, 60 and 80 mmHg thigh cuff inflations held for 1, 2, 3 and 4 min, respectively, in 14 supine subjects. One min of cuff deflation to 0 mmHg separated occlusions. Nine other subjects underwent HUT through the following angles held for 30s each: -12 deg., -6 deg., 0 deg., 12 deg., 30 deg., 54 deg., and 90 deg. HUT calf venous pressure data were interpolated from Katkov and Chestukhin; these data correspond to 70-80% of calculated calf venous pressure changes (pgh). Liquid metal-in-silastic strain gauges measured calf volume for both venous occlusion and HUT compliance. Relaxed calf compliance in supine subjects equaled 4.6 +/- 0.4 ml/mmHg (X +/- SE), as measured with venous occlusion. Calf compliance during HUT equaled 4.6 +/- 1.0 ml/mmHg. Therefore, calf compliance in supine, relaxed subjects equals that measured during head-up tilt. We conclude that the minimal calf muscle activation which occurs during HUT does not importantly affect calf compliance.

  3. Simulation of Cardiovascular Response to the Head-Up/Head-Down Tilt at Different Angles

    Science.gov (United States)

    Liu, Yang; Lu, Hong-Bing; Jiao, Chun; Zhang, Li-Fan

    2008-06-01

    The disappearance of hydrostatic pressure is the original factor that causes the changes of cardiovascular system under microgravity. The hydrostatical changes can be simulated by postural changes. Especially the head-down position can be used to simulate the effects of microgravity. The goal of this investigation was to develop a mathematical model for simulation of the human cardiovascular responses to acute and prolonged exposure under microgravity environment. We were particularly interested in the redistribution of transmural pressures, flows, blood volume, and the consequent alterations in local hemodynamics in different cardiovascular compartments during acute exposure and chronic adjustments. As a preliminary study, we first developed a multi-element, distributed hemodynamic model of human cardiovascular system, and verified the model to simulate cardiovascular changes during head up/down tilt at various angles.

  4. Mesenteric artery response to head-up tilt-induced central hypovolaemia and hypotension

    DEFF Research Database (Denmark)

    Perko, M J; Madsen, P; Perko, Grazyna

    1997-01-01

    Superior mesenteric artery (SMA) blood flow and impedance were evaluated by duplex ultrasound during head-up tilt (HUT)-induced central hypovolaemia and hypotension in eight healthy volunteers. HUT induced a reduction in cardiac stroke volume from 88.8 +/- 6.3 to 64.7 +/- 6.3 ml (mean +/- SEM; P ... the normotensive and the hypotensive phase of HUT, the SMA diameter (5.7 +/- 0.03 mm) and blood flow (514 +/- 75 ml min-1) did not change significantly, although the end-diastolic velocity increased from 9.7 +/- 4.8 to 39.7 +/- 4.0 cm s-1 (P ... or reduced arterial pressure, supports a reduction in the SMA impedance as it was reproduced during a meal test when a moderate reduction in mean arterial pressure (87 +/- 4 to 80 +/- 4 mm Hg; P = 0.04) was accompanied by a ninefold increase in the end-diastolic velocity (P

  5. Muscle oxygen saturation increases during head-up tilt-induced (pre)syncope

    DEFF Research Database (Denmark)

    Lund, A.; Sorensen, H.; Jensen, T. W.

    2017-01-01

    Aim To evaluate whether muscle vasodilatation plays a role for hypotension developed during central hypovolaemia, muscle oxygenation (SmO2) was examined during (pre)syncope induced by head-up tilt (HUT). Skin blood flow (SkBF) and oxygenation (SskinO2) were determined because evaluation of SmO2 may...... be affected by superficial tissue oxygenation. Furthermore, we evaluated cerebral oxygenation (ScO2) and middle cerebral artery mean blood flow velocity (MCAvmean). Methods Twenty healthy male volunteers (median age 24 years; range 19–38) were subjected to passive 50° HUT for 1 h or until (pre)syncope. ScO2......)syncope was associated with an increase in SmO2 despite reduced SskinO2 and SkBF, supporting that muscle vasodilation plays an important role in the circulatory events leading to hypotension during HUT....

  6. Heart rate variability in athletes and nonathletes at rest and during head-up tilt

    Directory of Open Access Journals (Sweden)

    F.S. Martinelli

    2005-04-01

    Full Text Available The purpose of the present study was to determine if autonomic heart rate modulation, indicated by heart rate variability (HRV, differs during supine rest and head-up tilt (HUT when sedentary and endurance-trained cyclists are compared. Eleven sedentary young men (S and 10 trained cyclists (C were studied. The volunteers were submitted to a dynamic ECG Holter to calculate HRV at rest and during a 70º HUT. The major aerobic capacity of athletes was expressed by higher values of at anaerobic threshold and peak conditions (P < 0.05. At rest the athletes had lower heart rates (P < 0.05 and higher values in the time domain of HRV compared with controls (SD of normal RR interval, SDNN, medians: 59.1 ms (S vs 89.9 ms (C, P < 0.05. During tilt athletes also had higher values in the time domain of HRV compared with controls (SDNN, medians: 55.7 ms (S vs 69.7 ms (C, P < 0.05. No differences in power spectral components of HRV at rest or during HUT were detected between groups. Based on the analysis of data by the frequency domain method, we conclude that in athletes the resting bradycardia seems to be much more related to changes in intrinsic mechanisms than to modifications in autonomic control. Also, HUT caused comparable changes in sympathetic and parasympathetic modulation of the sinus node in both groups.

  7. Short pain-provoked head-up tilt test for the confirmation of vasovagal syncope.

    Science.gov (United States)

    Adamec, Ivan; Mišmaš, Antonija; Zaper, Dinka; Junaković, Anamari; Hajnšek, Sanja; Habek, Mario

    2013-06-01

    We investigated a short pain-provoked head-up tilt (PP-HUT) and the Calgary Syncope Symptom Score in a group of patients with clinically diagnosed vasovagal syncope and group of neurological patients without transient loss of consciousness. We included 127 consecutive patients who were investigated in our laboratory. The group 1 included 56 patients who after appropriate investigations were diagnosed with vasovagal syncope. The group 2 included 70 neurological patients without transient loss of consciousness. The subjects were tilted to 70° for a maximum period of 10 min or until symptoms occurred. If there were no symptoms after initial 10 min, a painful stimulus with the insertion of 0.7 mm needle into the dorsum of hand subcutaneously for 30 s was performed with the patient in the tilted for further 5 min. Calgary Syncope Symptom Score was calculated for all patients. In the group 1, significantly higher number of patients had positive results on PP-HUT (36 vs. 6 patients, respectively; p syndrome (3 vs. 1 patient, respectively; p = 0.32) between groups. PP-HUT had sensitivity of 65.9 % (95 % CI 0.49-0.79) and specificity of 89.7 % (95 % CI 0.75-0.97). The CSSS had sensitivity of 58.5 % (95 % CI 0.42-0.73) and specificity of 46.1 % (95 % CI 0.30-0.63). PP-HUT has a higher diagnostic rate than the CSSS and provides a rapid alternative to conventional methods.

  8. Effect of serotonin receptor blockade on endocrine and cardiovascular responses to head-up tilt in humans

    DEFF Research Database (Denmark)

    Matzen, S; Secher, N H; Knigge, U

    1993-01-01

    Effects of blockade of serotonin (5-HT) receptors on the integrated cardiovascular and endocrine adaptations during head-up tilt were investigated in normal men. In control experiments 50 degrees head-up tilt increased heart rate (HR), total peripheral resistance (TPR), plasma renin activity (PRA...... abolished the adrenomedullary response to hypotension without affecting cardiovascular tolerance or the activity of the pituitary-adrenal axis. The results suggest that serotonergic mechanisms may be involved in the integrated cardiovascular and endocrine responses to central blood volume depletion...

  9. Provocation of coronary vasospastic angina using an isoproterenol head-up tilt test.

    Science.gov (United States)

    Hung, Ming-Jui; Wang, Chao-Hung; Cherng, Wen-Jin

    2004-01-01

    The goals of this study were to determine the value of the isoproterenol (ISO) head-up tilt (HUT) test in detecting coronary vasospastic angina and to investigate the possible mechanism responsible for coronary artery spasm. The ISO + HUT test was performed in 16 patients with coronary artery spasm documented by the intracoronary ergonovine provocation test. Patients' blood pressure and heart rate were measured at baseline, during the ISO + HUT (phase I), and during HUT after discontinuation of ISO (phase II). Patients were categorized as test-positive if they developed angina with ST-segment elevation during testing. Eight patients (50%) were test-positive (5 in phase I and 3 in phase II). Between the test-positive and test-negative groups, no significant differences were noted in the changes in blood pressure throughout the test. However, there were significant differences in the changes in heart rate from supine to 2 minutes after HUT under ISO infusion (-17 +/-22 vs 11 +/-25 beats/minute; p=0.035). In those patients with a positive result in the phase I stage, the heart rate decreased initially after tilt-up, and then significantly increased later (from 85 +/-16 to 110 +/-27 beats/minute; p=0.043), when coronary vasospasm occurred. In those patients with a positive result in the phase II stage, coronary vasospasm occurred immediately after HUT, when there was an insignificant transient increase in heart rate from the supine to the HUT position (from 85 +/-12 to 92 +/-11 beats/minute; p=0.109). The ISO + HUT test can provoke coronary vasospasm with ST-segment elevation in 50% of the patients with coronary artery spasm, when combined with an extensional protocol of HUT after discontinuation of ISO. This study suggests that the induction of coronary artery spasm during HUT testing is associated with a rapid elevation of sympathetic activity during augmented parasympathetic activity.

  10. Head-up tilt test results in child twins with nervous mediated syncope.

    Science.gov (United States)

    Zhang, Wenhua; Wang, Shuo; Wang, Cheng; Liu, Liping; Lin, Ping; Li, Fang; Wu, Lijia; Zou, Runmei

    2016-10-15

    To investigate the familial genetic characteristics of syncope in children. A detailed medical history was taken from four twin pairs of children complaining of dizziness, headache, chest tightness, chest pain, prodromal symptoms of syncope or syncope, meanwhile, these patients were given routine physical examination, 12-lead ECG, echocardiography, Holter ECG, EEG, MRI of the head and other tests to exclude cardio-cerebrovascular and pulmonary diseases, with those with unknown origin for syncope undergoing head-up tilt test (HUTT) and inquiry of detailed family history. The four pairs of twins with syncope beginning at 7-12years and induced mostly by standing position (4/5), and positive family history was noted in two pairs. Vasovagal syncope (VVS)-vasoinhibitory response pattern was predominant in HUTT (4/5). The results and the response pattern in HUTT might diversify between two members within same twin pair: one appeared as vasoinhibitory response pattern and one postural orthostatic tachycardia syndrome (POTS) pattern in the first pair, one vasoinhibitory response pattern and one negative response pattern in the second pair, vasoinhibitory response pattern in the third pair and negative response pattern in the fourth pair. The hereditary factors may play a more important role in younger children with syncope. Environment and psychological factors may induced syncope attack. The results and the response pattern in HUTT are diversified and which might different between two members within twin pair. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  11. Toward chronocardiologic and chronomic insights: dynamics of heart rate associated with head-up tilting.

    Science.gov (United States)

    Kubo, Yutaka; Murakami, Shogo; Matsuoka, Osamu; Hotta, Norihiro; Oinuma, Sachiko; Shinagawa, Makoto; Omori, Keigi; Nunoda, Shinichi; Otsuka, Kuniaki; Ohkawa, Shin-ichiro; Cornélissen, Germaine; Halberg, Franz

    2003-10-01

    As a step towards investigating the chronome (i.e. the inferential endpoints of chaos, trends and rhythms) of heart rate (HR) variability (HRV), we investigated whether the fractality or complexity of HRV is affected by a head-up tilting (HUT) test in the morning after an overnight fast. Spectral and non-linear analyses of HR were performed on data gathered during an 80 degrees passive HUT test in 15 men and 28 women 32.8 +/- 11.5 years of age. The non-linear endpoints included the scaling exponents alpha1 (11 beats), which indicate fractal properties, calculated with detrended fluctuation analysis, and the approximate entropy (ApEn), a measure of overall complexity. Passive HUT increased alpha1 (from 0.986 +/- 0.217 to 1.370 +/- 0.185; P = 0.0001), but did not alter alpha2 (from 0.925 +/- 0.110 to 0.958 +/- 0.130; P = 0.19). A slight but statistically significant decrease in ApEn was seen during HUT (from 1.114 +/- 0.131 to 1.013 +/- 0.197; P = 0.002). In the tilt-up position, there was a statistically significant negative correlation between alpha1 and ApEn (r = -0.490; P tilt-up position, alpha1 was correlated weakly with HF (r = -0.343 and r = -0.322, respectively), and strongly with LF/HF (r = 0.557 and r = 0.795), respectively. There was also a negative correlation between ApEn and LF/HF (r = -0.406 and r = -0.357, respectively). alpha2 did not correlate with any spectral or non-linear measures of HRV. Short-term fractal properties and complexity of HR were lowered with orthostatic stress. Alterations of the autonomic activities could be partly responsible for these changes and await extension of such studies to assess the broad spectral element of HRV, that includes, with components of approximately 3.6 and approximately 10.5 s, cycles with very much lower frequencies, along the scales of hours and even years, that critically modulate the mislabeled (only relatively high- and low-frequency) components in the range of seconds or minutes.

  12. Modulation of plasma adrenomedullin by epinephrine infusion during head up tilt.

    Science.gov (United States)

    Roessler, Andreas; Goswami, Nandu; Haditsch, Bernd; Hinghofer-Szalkay, Helmut

    2011-03-01

    We investigated whether head up tilt (HUT) with and without simultaneous epinephrine infusion modulate plasma adrenomedullin. We studied eight healthy male volunteers, using two 5 min 70° HUT trials: control (saline infusion) and intervention (epinephrine infusion, titrated to a dose which increased supine systolic pressure by 20% above resting values). Protocols were randomized and separated by 2 weeks. Cardiac function and systolic time intervals, recorded using a phonocardiograph microphone, included left ventricular ejection time (LVET), pre-ejection period (PEP), PEP/LVET and electromechanical systole (QS2). Compared to saline infusion, epinephrine increased supine adrenomedullin (3.2 ± 0.8 pmol/l, i.e., mean ± SEM, respectively), heart rate (HR) (+11.3 ± 2.6 bpm), systolic pressure (+18.4 ± 2.6 mmHg) but decreased supine LVET, LVET corrected for HR (LVETi) and QS2-time (all p = 0.004). Despite similar HUT induced thoracic fluid shifts, reflected by similar thoracic impedance changes, HUT-induced adrenomedullin increases were minimal in epinephrine-supplemented men in comparison to controls (+8% vs. 42%). During HUT, epinephrine infusion decreased only the LVET (p = 0.039). Our findings confirm that short-term HUT increases plasma adrenomedullin. They further suggest that with increased supine epinephrine levels (epinephrine infusion clamping systolic arterial pressure at 120% control level), supine cardiac performance rises to a level similar to that during HUT, while adrenomedullin is still elevated with HUT. This might be in accordance with a 'dampening' role of adrenomedullin during catecholaminergic cardiovascular stimulation. As epinephrine is used as a drug to treat cardiac arrest and ventricular arrhythmias, our results may have important clinical/emergency resuscitation applications.

  13. Dynamic changes in the QT-R-R relationship during head-up tilt test in patients with vasovagal syncope.

    Science.gov (United States)

    Mizumaki, Koichi; Fujiki, Akira; Sakabe, Masao; Nishida, Kunihiro; Sugao, Masataka; Tsuneda, Takayuki; Nagasawa, Hidehiko; Inoue, Hiroshi

    2005-01-01

    QT interval is influenced by preceding R-R intervals and autonomic nervous tone. Changes in QT intervals during vasovagal reflex might reflect autonomic modulation of ventricular repolarization; however, this issue has not been fully elucidated. This study aimed to evaluate dynamic response of QT interval to transient changes in R-R interval during vasovagal syncope (VVS) induced by head-up tilt test. Eighteen patients with VVS and 18 age-and sex-matched controls were studied. All patients with VVS had a positive mixed-type response to head-up tilt and all controls had a negative response. CM5-lead digital electrocardiogram (ECG) was recorded and QT intervals were analyzed using Holter ECG analyzer. Using scatter plots of consecutive QT and the preceding R-R intervals, QT-R-R relations during tilt-up and tilt-back or during vasovagal reflex were independently fitted to an exponential curve: QT (second) = A + B x exp[k x R-R (second)]. During the tilt-up, A, B, and k did not differ between patients with VVS and controls. During the tilt back, k showed equivalent positive value compared to the tilt-up (4.1 +/- 1.3 vs -4.6 +/- 0.9) in controls. However, k remained negative (-1.3 +/- 1.5) during vasovagal reflex in patients with VVS. In six patients, in whom metoprolol was effective in eliminating VVS, QT-R-R relationship during the tilt-back became similar to that in controls. In patients with VVS, hysteresis of the QT-R-R relation is similarly shown during tilt-up as in controls, whereas this hysteresis is no longer evident and failure of QT prolongation is observed during VVS.

  14. Provocation of neurocardiogenic syncope by clomipramine administration during the head-up tilt test in vasovagal syndrome.

    Science.gov (United States)

    Theodorakis, G N; Markianos, M; Zarvalis, E; Livanis, E G; Flevari, P; Kremastinos, D T

    2000-07-01

    We sought to test the hypothesis that activation of the serotonergic system in patients with vasovagal syndrome during the head-up tilt test provokes syncope. Central serotonergic activation participates in the pathogenesis of neurocardiogenic syncope. Drugs increasing serotonin (5-HT) in the central nervous system have not been tested as drug challenges during the head-up tilt test with clomipramine (Clom-HUT). The serotonergic re-uptake inhibitor clomipramine was infused (5 mg in 5 min) at the start of Clom-HUT in 55 patients (mean age 40 +/- 17 years) with a positive history of recurrent neurocardiogenic syncope and in 22 healthy control subjects (mean age 46 +/- 15 years). Blood samples were taken at 0, 5, 10 and 20 min for estimation of plasma prolactin and cortisol as neuroendocrine indicators of central serotonergic responsivity. All subjects had been previously tested with a basic 60 degrees head-up tilt test (B-HUT) for 30 min, and if negative, isoproterenol infusion was given at the end of the test. Twenty-nine (53%) of the 55 patients and none of the 22 control subjects had a positive result in the B-HUT. With Clom-HUT, the proportion of patients who experienced a positive response increased to 80% (n = 44), although this happened to only one control subject. Prolactin and cortisol plasma levels increased significantly in the positive Clom-HUT patient group only. The results indicate an increased responsivity of the central serotonergic neural system in subjects with vasovagal syndrome, the activation of which leads to sympathetic withdrawal. The use of clomipramine infusion with the tilt test seems to considerably improve its diagnostic value.

  15. 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

    (RR) interval and finger blood pressure (Finapres) in 14 healthy individuals on three different days. The protocol was 1 h of supine rest and 1 h of 60-degree head-up tilt. Time-series of consecutive 300-s segments as well as 1024-s segments of RR intervals and systolic, diastolic and mean blood...... 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...

  16. Diagnostic value of the head-up tilt test and the R-test in patients with syncope

    Directory of Open Access Journals (Sweden)

    Debora Robba

    2006-12-01

    Full Text Available The diagnostic value of the head-up tilt test (HUTT in discovering vasovagal syndrome depends on the pre-test probability. An accurate anamnesis and clinical examination screens the patients indicated for the HUTT. In patients with unexplained syncope, the R-test is an alternative procedure to discover its cause. In our study, we evaluated the diagnostic significance of the HUTT in a group of 211 patients and of the R-test in a subgroup of 45 patients with negative HUTT results and with negative traditional Holter ECG monitoring (24 hr. (Heart International 2006; 3-4: 171-7

  17. Entropy in Investigation of Vasovagal Syndrome in Passive Head Up Tilt Test

    Directory of Open Access Journals (Sweden)

    Katarzyna Buszko

    2017-05-01

    Full Text Available This paper presents an application of Approximate Entropy (ApEn and Sample Entropy (SampEn in the analysis of heart rhythm, blood pressure and stroke volume for the diagnosis of vasovagal syndrome. The analyzed biosignals were recorded during positive passive tilt tests—HUTT(+. Signal changes and their entropy were compared in three main phases of the test: supine position, tilt, and pre-syncope, with special focus on the latter, which was analyzed in a sliding window of each signal. In some cases, ApEn and SampEn were equally useful for the assessment of signal complexity (p < 0.05 in corresponding calculations. The complexity of the signals was found to decrease in the pre-syncope phase (SampEn (RRI: 1.20–0.34, SampEn (sBP: 1.29–0.57, SampEn (dBP: 1.19–0.48, SampEn (SV: 1.62–0.91. The pattern of the SampEn (SV decrease differs from the pattern of the SampEn (sBP, SampEn (dBP and SampEn (RRI decrease. For all signals, the lowest entropy values in the pre-syncope phase were observed at the moment when loss of consciousness occurred.

  18. Computer program for analysis of hemodynamic response to head-up tilt test

    Science.gov (United States)

    Świątek, Eliza; Cybulski, Gerard; Koźluk, Edward; Piątkowska, Agnieszka; Niewiadomski, Wiktor

    2014-11-01

    The aim of this work was to create a computer program, written in the MATLAB environment, which enables the visualization and analysis of hemodynamic parameters recorded during a passive tilt test using the CNS Task Force Monitor System. The application was created to help in the assessment of the relationship between the values and dynamics of changes of the selected parameters and the risk of orthostatic syncope. The signal analysis included: R-R intervals (RRI), heart rate (HR), systolic blood pressure (sBP), diastolic blood pressure (dBP), mean blood pressure (mBP), stroke volume (SV), stroke index (SI), cardiac output (CO), cardiac index (CI), total peripheral resistance (TPR), total peripheral resistance index (TPRI), ventricular ejection time (LVET) and thoracic fluid content (TFC). The program enables the user to visualize waveforms for a selected parameter and to perform smoothing with selected moving average parameters. It allows one to construct the graph of means for any range, and the Poincare plot for a selected time range. The program automatically determines the average value of the parameter before tilt, its minimum and maximum value immediately after changing positions and the times of their occurrence. It is possible to correct the automatically detected points manually. For the RR interval, it determines the acceleration index (AI) and the brake index (BI). It is possible to save calculated values to an XLS with a name specified by user. The application has a user-friendly graphical interface and can run on a computer that has no MATLAB software.

  19. Respostas autonômicas cardíacas à manobra de tilt em adolescentes obesos Cardiac autonomic responses to head-up tilt in obese adolescents

    Directory of Open Access Journals (Sweden)

    Antônio Fernando Brunetto

    2005-10-01

    Full Text Available INTRODUÇÃO: A obesidade está associada às alterações do sistema nervoso autônomo. Estudos prévios em adultos têm mostrado que obesos apresentam resposta autonômica cardíaca diminuída frente a mudanças posturais. Contudo, pouco se sabe sobre o impacto do sobrepeso na adolescência quanto às respostas autonômicas ao estresse postural passivo. OBJETIVO: Comparar as respostas autonômicas cardíacas à manobra de tilt entre adolescentes obesos e não-obesos mediante análise da variabilidade da freqüência cardíaca (VFC. MÉTODOS: Quatorze adolescentes obesos (15,5±1,6 anos foram comparados com 20 adolescentes não-obesos (15,4±0,8 anos. A modulação autonômica cardíaca foi estudada mediante análise da variabilidade da freqüência cardíaca de trechos de cinco minutos de registro de intervalos RR antes e depois da inclinação da mesa de tilt a 70º. A VFC foi estudada no domínio do tempo (DT e no domínio da freqüência (DF. Os componentes espectrais foram estudados na baixa (LF e na alta freqüência (HF e pela razão LF/HF. RESULTADOS: Adolescentes obesos demonstraram menor HF em unidades normalizadas (38,2±11.1 vs 53,9±15,5, pINTRODUCTION: Obesity is associated with alterations of the autonomic nervous system. Previous studies in adults have shown that obese individuals present a decreased cardiac autonomic response to postural challenges. However, little is known about the impact of overweight on autonomic responses to passive postural stress in adolescents. OBJECTIVE: to compare cardiac autonomic responses to the head-up tilt maneuver between obese and non-obese adolescents by analyzing heart rate variability. METHODS: Fourteen obese adolescents (15.5±1.6 years were compared with twenty non-obese subjects (15.4±0.8 years. Cardiac autonomic modulation was studied by heart rate variability (HRV analysis of 5 minute RR interval recordings before and after a 70º head-up tilt maneuver. HRV was analyzed according to

  20. Distinctive Steady-State Heart Rate and Blood Pressure Responses to Passive Robotic Leg Exercise and Functional Electrical Stimulation During Head-up Tilt

    Directory of Open Access Journals (Sweden)

    Amirehsan Sarabadani Tafreshi

    2016-12-01

    Full Text Available Tilt tables enable early mobilization of patients by providing verticalization. But there is a high risk of orthostatic hypotension provoked by verticalization, especially after neurological diseases such as spinal cord injury. Robot-assisted tilt tables might be an alternative as they add passive robotic leg exercise (PE that can be enhanced with functional electrical stimulation (FES to the verticalization, thus reducing the risk of orthostatic hypotension. We hypothesized that the influence of PE on the cardiovascular system during verticalization depends on the verticalization angle, and FES strengthens the PE influence. To test our hypotheses, we investigated the PE effects on the cardiovascular parameters heart rate (HR, and systolic and diastolic blood pressures (sBP, dBP at different angles of verticalization in a healthy population. Ten healthy subjects on a robot-assisted tilt table underwent four different study protocols while HR, sBP and dBP were measured: (1 head-up tilt to 60° and 71° without PE; (2 PE at 20°, 40°, and 60° of head-up tilt; (3 PE while constant FES intensity was applied to the leg muscles, at 20°, 40°, and 60° of head-up tilt; (4 PE with variation of the applied FES intensity at 0°, 20°, 40°, and 60° of head-up tilt. Linear mixed models were used to model changes in HR, sBP, and dBP responses. The models show that: (1 head-up tilt alone resulted in statistically significant increases in HR and dBP, but no change in sBP. (2 PE during head-up tilt resulted in statistically significant changes in HR, sBP, and dBP, but not at each angle and not always in the same direction (i.e., increase or decrease of cardiovascular parameters. Neither adding (3 FES at constant intensity to PE nor (4 variation of FES intensity during PE had any statistically significant effects on the cardiovascular parameters.The effect of PE on the cardiovascular system during head-up tilt is strongly dependent on the verticalization

  1. Which is preferable for orthostatic hypotension diagnosis in older adults: active standing test or head-up tilt table test?

    Directory of Open Access Journals (Sweden)

    Aydin AE

    2017-01-01

    Full Text Available Ali Ekrem Aydin,1 Pinar Soysal,2 Ahmet Turan Isik1 1Center for Aging Brain and Dementia, Department of Geriatric Medicine, Faculty of Medicine, Dokuz Eylul University, Izmir, Turkey; 2Kayseri Education and Research Hospital, Geriatric Center, Kayseri, Turkey Background: Correct evaluation of orthostatic hypotension (OH is crucial in geriatric practice, since OH is associated with mortality and morbidity. The study aimed to determine the most appropriate method for measuring blood pressure in transition from supine to upright position in order to diagnose OH in older adults.Methods: Active standing test (AST and head-up tilt table (HUT test as well as comprehensive geriatric assessment (CGA, including mini-mental state examination or the cognitive state test, mini-nutritional assessment, basic and instrumental activities of daily living, and Tinetti performance-oriented mobility assessment indexes, were performed in 290 geriatric patients.Results: The prevalence of OH during HUT and AST was 19% and 37%, respectively. In patients with OH during HUT, the frequency of dementia and recurrent falls were higher (P<0.05; on the other hand, the levels of serum vitamin D and albumin and estimated glomerular filtration rate were lower (P<0.05. However, all these parameters for OH during AST were not significant (P>0.05. Comparison of the groups according to CGA measurements revealed significant differences in terms of cognition, nutritional status, activities of daily life, and balance function in patients with OH only during HUT (P<0.05, but not during AST (P>0.05. The sensitivity, specificity, positive predictive value, and negative predictive values of AST were 49.0%, 65.5%, 25.0%, and 84.6% respectively, according to HUT.Conclusion: The results suggest that orthostatic blood pressure changes determined by HUT might be of higher clinical significance than that by AST in older adults. It might be important that the evaluation of OH by HUT should be

  2. Differences in autonomic balance in patients with cardioinhibitory and vasodepressor type of reflex syncope during head-up tilt test and active standing

    DEFF Research Database (Denmark)

    Holmegard, Haya N; Benn, Marianne; Kaijer, Michelle

    2012-01-01

    To improve the pathophysiological understanding of cardioinhibitory and vasodepressor reflex syncope, by evaluating orthostatic effects on electrical and hemodynamic variables. To unravel the pathogeneses further, we studied these effects during both the passive head-up tilt test and the active...... standing test....

  3. Which is preferable for orthostatic hypotension diagnosis in older adults: active standing test or head-up tilt table test?

    Science.gov (United States)

    Aydin, Ali Ekrem; Soysal, Pinar; Isik, Ahmet Turan

    2017-01-01

    Correct evaluation of orthostatic hypotension (OH) is crucial in geriatric practice, since OH is associated with mortality and morbidity. The study aimed to determine the most appropriate method for measuring blood pressure in transition from supine to upright position in order to diagnose OH in older adults. Active standing test (AST) and head-up tilt table (HUT) test as well as comprehensive geriatric assessment (CGA), including mini-mental state examination or the cognitive state test, mini-nutritional assessment, basic and instrumental activities of daily living, and Tinetti performance-oriented mobility assessment indexes, were performed in 290 geriatric patients. The prevalence of OH during HUT and AST was 19% and 37%, respectively. In patients with OH during HUT, the frequency of dementia and recurrent falls were higher (P0.05). Comparison of the groups according to CGA measurements revealed significant differences in terms of cognition, nutritional status, activities of daily life, and balance function in patients with OH only during HUT (P0.05). The sensitivity, specificity, positive predictive value, and negative predictive values of AST were 49.0%, 65.5%, 25.0%, and 84.6% respectively, according to HUT. The results suggest that orthostatic blood pressure changes determined by HUT might be of higher clinical significance than that by AST in older adults. It might be important that the evaluation of OH by HUT should be included in daily geriatric practice.

  4. Short-term heart rate variability response to head-up tilt in young syncope patients and controls with respect to age.

    Science.gov (United States)

    Dickhaus, Hartmut; Maier, Christoph; Khalil, Markus; Ulmer, Herbert

    2006-01-01

    This study aims at characterizing the short-term time-courses of time- and frequency-domain heart rate variability (HRV) parameters during head-up tilt test (HUTT). Data from 44 young patients with a history of syncope and 34 age-matched controls was analysed in two age-groups related to puberty ( or =14 years), and separately for gender, by extracting minute-by-minute progression of mean RR-interval, standard deviation of RR-intervals (SDNN) and their first difference (SDSD) as well as low-frequency (LF, 0.05-0.15 Hz) energy, high-frequency (HF, 0.15-0.4 Hz) energy and the LF/HF-ratio. Time-courses were individually normalized and averaged after synchronization to the events of tilt and tilt-back/syncope. We observed remarkable age-related differences not only with respect to response to tilting but also regarding the differentiation of patients with positive HUTT from controls with negative HUTT. ROC-analysis in three regions of interest (0-2 min after tilt, 2-5 min after tilt, 5-2 min before tilt-back) revealed generally much weaker and less persistent differences in younger subjects whereas in elders the differences were clearer and often most pronounced immediately before syncope. For both age-groups, the relative change of mean RR provided best separation, however in elders in the ROI just before syncope (sensitivity: 74%, specificity 80%) in young immediately after tilt (sens.: 71%, spec.: 74%). In elder subjects, the relative reduction of SDNN 2-5 minute after tilt achieved almost the same performance (sens.: 74%, spec. 80%) as in the ROI before syncope (sens. 78%, spec. 73%), indicating the existence of rather early precursors of syncope that might help to predict the outcome of the HUTT in subjects in or after puberty.

  5. The effect of head up tilting on bioreactance cardiac output and stroke volume readings using suprasternal transcutaneous Doppler as a control in healthy young adults.

    Science.gov (United States)

    Zhang, Jie; Critchley, Lester A H; Lee, Daniel C W; Khaw, Kim S; Lee, Shara W Y

    2016-10-01

    To compare the performance of a bioreactance cardiac output (CO) monitor (NICOM) and transcutaneous Doppler (USCOM) during head up tilting (HUT). Healthy young adult subjects, age 22 ± 1 years, 7 male and 7 female, were tilted over 3-5 s from supine to 70° HUT, 30° HUT and back to supine. Positions were held for 3 min. Simultaneous readings of NICOM and USCOM were performed 30 s into each new position. Mean blood pressure (MBP), heart rate (HR), CO and stroke volume (SV), and thoracic fluid content (TFC) were recorded. Bland-Altman, percentage changes and analysis of variance for repeated measures were used for statistical analysis. Pre-tilt NICOM CO and SV readings (6.1 ± 1.0 L/min and 113 ± 25 ml) were higher than those from USCOM (4.1 ± 0.6 L/min and 77 ± 9 ml) (P effect proportional changes in SV readings of 23 ± 15 % (30° half tilt) and 44 ± 11 % (70° near full tilt), NICOM changes did not being 28 ± 10 and 33 ± 11 %. TFC decreased linearly with HUT. The NICOM does not provide linear changes in SV as predicted by physiology when patients are tilted. Furthermore there is a lack of agreement with USCOM measurements at baseline and during tilting.

  6. 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.

  7. Head-up tilt and hyperventilation produce similar changes in cerebral oxygenation and blood volume: an observational comparison study using frequency-domain near-infrared spectroscopy.

    Science.gov (United States)

    Meng, Lingzhong; Mantulin, William W; Alexander, Brenton S; Cerussi, Albert E; Tromberg, Bruce J; Yu, Zhaoxia; Laning, Kathleen; Kain, Zeev N; Cannesson, Maxime; Gelb, Adrian W

    2012-04-01

    During anesthesia, maneuvers which cause the least disturbance of cerebral oxygenation with the greatest decrease in intracranial pressure would be most beneficial to patients with intracranial hypertension. Both head-up tilt (HUT) and hyperventilation are used to decrease brain bulk, and both may be associated with decreases in cerebral oxygenation. In this observational study, our null hypothesis was that the impact of HUT and hyperventilation on cerebral tissue oxygen saturation (SctO2) and cerebral blood volume (CBV) are comparable. Surgical patients without neurological disease were anesthetized with propofol-remifentanil. Before the start of surgery, frequency-domain near-infrared spectroscopy was used to measure SctO2 and CBV at the supine position, at the 30° head-up and head-down positions, as well as during hypoventilation and hyperventilation. Thirty-three patients were studied. Both HUT and hyperventilation induced small decreases in SctO2 [3.5 (2.6)%; P hyperventilation to an end-tidal carbon dioxide (ETCO2) of 25 mmHg (from 45 mmHg) in both SctO2 (P = 0.3) and CBV (P = 0.4). The small but statistically significant decreases in both SctO2 and CBV caused by HUT and hyperventilation are comparable. There was no correlation between the decreases in SctO2 and CBV and the decreases in blood pressure and cardiac output during head-up and head-down tilts. However, the decreases in both SctO2 and CBV correlate with the decreases in ETCO2 during ventilation adjustment.

  8. Contribution of head-up tilt testing and ATP testing in assessing the mechanisms of vasovagal syndrome: preliminary results and potential therapeutic implications.

    Science.gov (United States)

    Flammang, D; Erickson, M; McCarville, S; Church, T; Hamani, D; Donal, E

    1999-05-11

    In patients with vasovagal syndrome, head-up tilt testing may reproduce symptoms generally associated with vasodepression. Recent research suggests ATP testing identifies patients with abnormal vagal cardiac inhibition. This preliminary study examined the joint contribution of both tests in identifying underlying mechanisms in the general population with vasovagal syndrome. Both tests were performed in random order during 1 session and outside of predominant sympathetic periods in 72 patients hospitalized for syncope (n=56) or presyncope (n=16) for whom no cardiac or extracardiac cause was found. For passive and isoproterenol-provocative tilt testing by standard protocol, reproduction of symptoms defined a positive test. The ATP test consisted of injecting ATP 20 mg IV at bedside, continuously monitoring ECG and blood pressure; a vagal cardiac pause >10 seconds defined a positive test. For most patients (64%), >/=1 test was positive. Of the 41 patients (57%) with a positive tilt test (either passive or provoked by isoproterenol), 32% had cardiac disease; none had significant bradycardia (vasovagal symptoms in most patients and that vagal cardiac inhibition increases with age.

  9. Role of head-up tilt table testing in patients with syncope or transient loss of consciousness

    Directory of Open Access Journals (Sweden)

    Toshiyuki Furukawa, MD, PhD

    2017-12-01

    Full Text Available The tilt table test (TTT is a useful method for the management of reflex syncope. However, the TTT is incomplete and has several problems. The indications for this test are established using guidelines. The TTT is not suitable for all syncopal patients. It is currently unclear (1 When should the TTT be used, (2 for which types of patients TTT should be performed, and (3 does the TTT provide useful information to guide indication for pacing therapy for reflex syncope. The answers to these questions appear in recent reports from two guidelines published by the European Society of Cardiology and the Japan Circulation Society. The indications for TTT do not apply to all syncopal patients, but selected patients. For patients with low risks and rare syncopal events, the TTT is not necessary, even when diagnoses are unconfirmed. The TTT is used not only for diagnosis of reflex syncope, but also for many clinical management of several conditions (i.e., exclusion of cardiac syncope. Positive TTT results cannot predict the effects of pacing therapy for reflex syncope. The decision to use pacing therapy should be based on documented electrocardiograms and other findings, including TTT results. Keywords: Tilt table testing, Reflex syncope, Pacemaker, Italian protocol, Management of syncope

  10. Infants with univentricular heart have reduced heart rate and blood pressure responses to side motion and altered responses to head-up tilt.

    Science.gov (United States)

    Kirjavainen, Turkka; Viskari, Suvi; Pitkänen, Olli; Jokinen, Eero

    2005-02-01

    Cardiovascular control was studied in infants with univentricular heart (UVH). Side motion tests and 45-s 45 degrees head-up tilt tests were performed in 11 control and 9 UVH infants at the age of 13 +/- 3.2 wk. In addition, heart rate (HR) reactions to spontaneous arousals and HR variability during slow-wave sleep (SWS) were determined. All UVH infants had been hypoxic for several weeks, and during the sleep study the mean arterial oxyhemoglobin saturation was 82 +/- 5%. Tests were done at night during SWS, confirmed by polysomnographic recording. Continuous beat-to-beat blood pressure (BP) was measured. In the side-motion tests, control infants consistently showed a transient increase in HR and BP. This response was markedly reduced in all of the UVH infants (P < 0.0001). In tilt tests, the UVH infants showed normal BP responses, but, although a sustained 2.0% decrease in HR was observed in the controls, the UVH infants presented with a sustained 2.6% mean HR increase (P = 0.005). The UVH infants also showed attenuated HR acceleration during spontaneous arousals (P = 0.01), but HR variability did not differ significantly from the controls. In conclusion, UVH infants with chronic hypoxia exhibit defective vestibulosympathetic pathways, as expressed by an absence of acute HR and BP reactivity to side motion. HR reactions to postural challenge and spontaneous arousal are also altered. Autonomic function abnormalities in these infants are suggested to be secondary to hypoxia.

  11. How does the estimated phase of menstrual cycle or menopause influence the prevalence of vasovagal syncope induced by head-up tilt test.

    Science.gov (United States)

    Pietrucha, Artur Z; Jędrzejczyk-Spaho, Joanna; Konduracka, Ewa; Bzukała, Irena; Krawczyk, Krzysztof; Kruszelnicka-Kwiatkowska, Olga; Nessler, Jadwiga

    2017-01-01

    The purpose of this study was to evaluate the prevalence of syncope induced by head-up tilt test (HUTT) and the type of positive vasovagal response to the orthostatic stress in a relationship to the estimated phase of menstrual cycle (follicular phase, luteal phase) or menopause. We observed a cohort of 500 women at age 13-89 years (median of age 37.5), referred to HUTT. Phase of the menstrual cycle was determined on the basis of the usual length of menstrual cycle and the day of the cycle at the time of the study. We assumed that the length of the luteal phase is constant and it is 14 days. In premenopausal patients, the occurrence of the mixed and cardioinhibitory response was significantly more frequent in comparison to postmenopausal women (48.8 vs. 35.1% and 19.7 vs. 12.4%, respectively; p < 0.00001), while the occurrence of the vasodepressive one was significantly less frequent (7.3% vs. 28.6%; p < 0.00001) in that group of patients. Women in follicular phase presented vasodepressive response during HUTT more often than woman in the luteal phase (10.0% vs. 4.1%, p < 0.00001). Among women referred for HUTT, the prevalence of the vasovagal syndrome did not differ between those that were pre- and post-menopausal. Higher incidence of vasodepressive reaction in postmenopausal women was observed. Among the premenopausal women, the vasodepressive type of vasovagal syndrome occurred more often in follicular then in luteal phase.

  12. Síncope no idoso: utilidade diagnóstica da massagem do seio carotídeo na posição ortostática durante o "tilt test" Syncope in the elderly: diagnostic utility of carotid sinus massage in the head-up tilt test

    Directory of Open Access Journals (Sweden)

    Marcos Benchimol

    2003-03-01

    Full Text Available Um senhor aposentado veio à consulta com história de desmaios há vários meses e uma série de exames cardiológicos e de neuroimagem inconclusivos. Medicado com carbamazepina, os desmaios persistiram, ocasionando ferimentos na face e nos braços. Durante o "tilt test" não sensibilizado farmacologicamente, a massagem do seio carotídeo na posição ortostática (mesa inclinada a 60° produziu assistolia, perda da consciência e queda drástica da pressão arterial por 5 segundos. A mesma manobra na posição supina não provocou sintomas ou alterações hemodinâmicas. Implantado marca-passo de dupla câmara e suspensa a carbamazepina, os desmaios não se repetiram ao longo dos 18 meses de acompanhamento, confirmando o diagnóstico de hipersensibilidade do seio carotídeo com resposta cárdio-inibitória. Este caso ilustra e reafirma a utilidade do "tilt test" e da inclusão da massagem dos seios carotídeos na posição ortostática no protocolo de investigação de todo paciente com síncope de causa inaparente.A 71-year-old man presented with a 6-month history of fainting. Consciousness was quickly regained without clouding or confusion. Ancillary investigations were inconclusive and he was treated with carbamazepine. The fainting spells did not cease and he was referred for a tilt-table test exam. In the head-up position (table tilted at 60°, massage of the carotid sinus was immediately followed by asystole, unconsciousness, and a sharp drop in arterial pressure for 5 seconds. The same procedure in the lying position did not elicit clinical symptoms or hæmodynamic imbalance. A diagnosis of carotid sinus hypersensitivity with a cardio-inhibitory response pattern was made. Carbamazepine was withdrawn and a double-chamber pacemaker was implanted in his right ventricle. He remained symptom-free for the ensuing 18 months. This case supports the diagnostic utility of carotid sinus massage during the head-up tilt test in patients with

  13. Heads Up: Concussion in Youth Sports

    Medline Plus

    Full Text Available ... What's this? Submit What's this? Submit Button Concussion in Youth Sports Training course: This page has moved ... What's this? Submit What's this? Submit Button Connect with HEADS UP & CDC's Injury Center HEADS UP Resources ...

  14. Heads Up: Concussion in Youth Sports

    Medline Plus

    Full Text Available ... this? Submit Button Connect with HEADS UP & CDC's Injury Center HEADS UP Resources File Formats Help: How ... for Disease Control and Prevention , National Center for Injury Prevention and Control , Division of Unintentional Injury Prevention ...

  15. Heads Up to High School Sports

    Science.gov (United States)

    ... submit" value="Submit" /> HEADS UP to School Sports Recommend on Facebook Tweet Share Compartir To help ... organizations, developed the HEADS UP: Concussion in School Sports initiative and materials. Specific Concussion Information for... Coaches ...

  16. Tilted ECG - An unusual tilt test response

    Directory of Open Access Journals (Sweden)

    Anunay Gupta, MD, DM

    2017-03-01

    Full Text Available Tilt testing is a commonly used diagnostic tool to evaluate syncope of undetermined etiology. We hereby describe a twelve year old male child who developed presyncope during provocative head up tilt testing along with ST segment elevation in cardiac monitor during presyncope. Patient underwent repeat head up tilt testing along with holter monitoring which showed a left bundle branch block escape rhythm. Hence development of ST elevation was due to the improper filter application in single lead ECG monitor. This case highlights the importance of filters in electrocardiographic monitoring.

  17. Tympanic membrane temperature decreases during head up tilt

    DEFF Research Database (Denmark)

    Lorr, David; Lund, Anton; Fredrikson, Mats

    2017-01-01

    monitored by transcranial Doppler which determined the mean blood flow velocity in the middle cerebral artery (MCA Vmean) and by near infrared spectroscopy assessed frontal lobe oxygenation (ScO2), while skin blood flow (SkBF) was evaluated by laser Doppler flowmetry. RESULTS: During HUT, TMT decreased by 0...

  18. Projection/Reflection Heads-up Display

    Data.gov (United States)

    National Aeronautics and Space Administration — To address the NASA need for an EVA information display device, Physical Optics Corporation (POC) proposes to develop a new Projection/Reflection Heads-up Display...

  19. MEMS scanned laser head-up display

    Science.gov (United States)

    Freeman, Mark O.

    2011-03-01

    Head-up displays (HUD) in automobiles and other vehicles have been shown to significantly reduce accident rates by keeping the driver's eyes on the road. The requirements for automotive HUDs are quite demanding especially in terms of brightness, dimming range, supplied power, and size. Scanned laser display technology is particularly well-suited to this application since the lasers can be very efficiently relayed to the driver's eyes. Additionally, the lasers are only turned on where the light is needed in the image. This helps to provide the required brightness while minimizing power and avoiding a background glow that disturbs the see-through experience. Microvision has developed a couple of HUD architectures that are presented herein. One design uses an exit pupil expander and relay optics to produce a high quality virtual image for built-in systems where the image appears to float above the hood of the auto. A second design uses a patented see-through screen technology and pico projector to make automotive HUDs available to anyone with a projector. The presentation will go over the basic designs for the two types of HUD and discuss design tradeoffs.

  20. Head-up suspension in humans: effects on sympathetic vasomotor activity and cardiovascular responses.

    Science.gov (United States)

    Shamsuzzaman, A S; Sugiyama, Y; Kamiya, A; Fu, Q; Mano, T

    1998-05-01

    We hypothesized that muscle sympathetic nerve activity (MSNA) and cardiovascular responses to the conventional head-up tilt (HUT) are different from those to head-up suspension (HUS) because of antigravity muscle activity. The MSNA from the tibial nerve, heart rate, blood pressure, stroke volume, cardiac output, and calf blood flow were measured in 13 healthy young subjects. Left atrial diameter was measured by two-dimensional echocardiography in another nine subjects. The resting MSNA and cardiovascular responses at a low level (20 degrees) of orthostasis were similar during both modes. At higher levels (40 and 60 degrees), the responses of MSNA, heart rate, stroke volume, and cardiac output were significantly stronger and there was a smaller reduction in calf blood flow during HUT than during HUS (P antigravity muscles during HUT may have additive effects on sympathetic vasoconstrictor and cardiovascular responses to orthostatic stress.

  1. Improvement of Head-Up Display Standards. Volume 3. An Evaluation of Head-Up Display Safety.

    Science.gov (United States)

    1987-09-01

    result was the PERSEPOLIS display (21). These displays both make use of the fundamental relationship "I’. between ALPHA, GAMMA, and THETA and use air...designed to emphasize the unique relationship between THETA, GAMMA, and ALPHA. The Klopfstein and PERSEPOLIS HUDs, designed for transport airplanes made...CSF 21 H. Suisse, Head-Up Display System -- PERSEPOLIS Symbology, Dassault Report DGT-16433, September 1979 22 "A Word from the Navy," ALPA Head-Up

  2. Sleeping with the head [up] of the bed tilted up: physiology & therapy

    OpenAIRE

    FAN, CHIE WEI

    2008-01-01

    Orthostatic hypotension (OH) is common and affects people with increasing age and co-morbidity. It is associated with increased vascular risk, falls and dementia. While pharmacological and non-pharmacological treatments exist they are either poorly tolerated or poorly studied. One of the non-pharmacological therapies is sleeping with the head of the bed elevated (SHU). This treatment option has been described since the 1940’s. However, the scientific evidence for SHU, up to now, has been case...

  3. Heads Up! Play it Safe When it Comes to Concussions

    Centers for Disease Control (CDC) Podcasts

    2007-05-21

    As many as 3.8 million sports- and recreation-related concussions are estimated to occur in the United States each year. This podcast is a radio interview with CDC's Dr. Julie Gilchrist on the newly available “Heads Up: Concussion in Youth Sports" tool kit, which was developed to provide information to coaches, parents, and athletes involved in youth sports on preventing, recognizing, and responding to a concussion.  Created: 5/21/2007 by National Center for Injury Prevention and Control, Division of Injury Response.   Date Released: 10/31/2007.

  4. Influence of passive leg movements on blood circulation on the tilt table in healthy adults

    Directory of Open Access Journals (Sweden)

    Czell David

    2004-10-01

    Full Text Available Abstract Background One problem in the mobilization of patients with neurological diseases, such as spinal cord injury, is the circulatory collapse that occurs while changing from supine to vertical position because of the missing venous pump due to paralyzed leg muscles. Therefore, a tilt table with integrated stepping device (tilt stepper was developed, which allows passive stepping movements for performing locomotion training in an early state of rehabilitation. The aim of this pilot study was to investigate if passive stepping and cycling movements of the legs during tilt table training could stabilize blood circulation and prevent neurally-mediated syncope in healthy young adults. Methods In the first experiment, healthy subjects were tested on a traditional tilt table. Subjects who had a syncope or near-syncope in this condition underwent a second trial on the tilt stepper. In the second experiment, a group of healthy subjects was investigated on a traditional tilt table, the second group on the tilt ergometer, a device that allows cycling movements during tilt table training. We used the chi-square test to compare the occurrence of near-syncope/syncope in both groups (tilt table/tilt stepper and tilt table/tilt ergometer and ANOVA to compare the blood pressure and heart rate between the groups at the four time intervals (supine, at 2 minutes, at 6 minutes and end of head-up tilt. Results Separate chi-square tests performed for each experiment showed significant differences in the occurrence of near syncope or syncope based on the device used. Comparison of the two groups (tilt stepper/ tilt table in experiment one (ANOVA showed that blood pressure was significantly higher at the end of head-up tilt on the tilt stepper and on the tilt table there was a greater increase in heart rate (2 minutes after head-up tilt. Comparison of the two groups (tilt ergometer/tilt table in experiment 2 (ANOVA showed that blood pressure was significantly

  5. Effects of tilting on central hemodynamics and homeostatic mechanisms in cirrhosis

    DEFF Research Database (Denmark)

    Møller, Søren; Nørgaard, Annette; Henriksen, Jens H

    2004-01-01

    and RAAS were related to changes in arterial blood pressure, systemic vascular resistance, heart rate, non-CBV, plasma volume, and arterial compliance. In conclusion, cardiovascular and humoral responses to changes in posture are clearly abnormal in patients with cirrhosis. Head-up tilting decreases...... in the supine patient, we studied the humoral and central hemodynamic responses to changes with posture. Twenty-three patients with alcoholic cirrhosis (Child-Turcotte-Pugh classes A/B/C: 2/13/8) and 14 healthy controls were entered. Measurements of central hemodynamics and activation of SNS and RAAS were taken...... in the supine position, after 30 degrees head-down tilting, and after 60 degrees passive head-up tilting for a maximum of 20 minutes. After the head-up tilting, the central blood volume (CBV) decreased in both groups, but the decrease was significantly smaller in patients than in controls (-19% vs. -36%, P

  6. Prueba de inclinación (“Head-up Tilt Test”), lecciones aprendidas en 564 casos consecutivos: Lessons Learned from 564 Consecutive Cases Head-Up Tilt Test

    OpenAIRE

    Oswaldo Gutiérrez-Sotelo; Yorleny Alfaro-Badilla

    2012-01-01

    Introducción. El síncope es un motivo frecuente de consulta; el mecanismo causal más común es el reflejo, que incluye el síncope neurocardiogénico (SN), la hipotensión ortostática, la hipersensibilidad del seno carotídeo, entre otros. Estas variantes se valoran mediante la prueba de inclinación, con o sin estímulo farmacológico con nitroglicerina. El presente estudio recoge la experiencia con este examen auxiliar realizado en nuestro centro en los últimos 8 años. Material y métodos. Es un est...

  7. Stroke volume of the heart and thoracic fluid content during head-up and head-down tilt in humans

    DEFF Research Database (Denmark)

    van Lieshout, J J; Harms, M P M; Pott, F

    2005-01-01

    The stroke volume (SV) of the heart depends on the diastolic volume but, for the intact organism, central pressures are applied widely to express the filling of the heart.......The stroke volume (SV) of the heart depends on the diastolic volume but, for the intact organism, central pressures are applied widely to express the filling of the heart....

  8. Using Kalman filtering to predict time-varying parameters in a model predicting baroreflex regulation during head-up tilt

    DEFF Research Database (Denmark)

    Matzuka, Brett; Mehlsen, Jesper; Tran, Hien

    2015-01-01

    are sparse, typical studies only include measurements of heart rate and blood pressure, as a result it is difficult to determine what mechanisms that are impaired. It is known, that blood pressure regulation is mediated by changes in heart rate, vascular resistance, cardiac contractility and a number......The cardiovascular control system is continuously engaged to maintain homeostasis, but it is known to fail in a large cohort of patients suffering from orthostatic intolerance. Numerous clinical studies have been put forward to understand how the system fails, yet non-invasive clinical data...

  9. Technical feasibility and safety of an intraoperative head-up display device during spine instrumentation.

    Science.gov (United States)

    Yoon, Jang W; Chen, Robert E; Han, Phillip K; Si, Phong; Freeman, William D; Pirris, Stephen M

    2017-09-01

    The primary aim of this study was to determine the safety and feasibility of capturing and streaming neuronavigation images onto a head-up display during spine instrumentation. Using a novel device, neuronavigation images were captured and transferred wirelessly via a password-encrypted network to the head-up display. At the end of the procedure, the surgeons completed a survey to gather their opinions of the system. Forty pedicle screws were placed using the head-up display. The average screw placement time was slightly shorter when the head-up display was used (4.13 min with vs. 4.86 min without). The post-procedure survey demonstrated that 79% of surgeon's responses were positive. A wearable head-up display can benefit current neuronavigation systems, but larger, outcomes-based trials are needed. Higher processing speed would allow streaming of higher resolution images. Along with an enlarged display, these may significantly improve utilization of this technology. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Heads Up

    Science.gov (United States)

    ... top priority.Whether you are a parent , youth sports coach , school coach , school professional , or health care provider , this ... am a… Youth Sports League Coach Parent Athlete Sports Official School Sports Coach Parent Athlete Sports Official School School ...

  11. Operational Problems Associated with Head-Up Displays during Instrument Flight.

    Science.gov (United States)

    1980-10-01

    Retrieval USAF DC-7 Bendix Microvision IMC Landing Aid FAA TABLE 1 OPERATIONAL HEAD-UP DISPLAYS IN CIVIL AND U. S. MILITARY SERVICE 26 for most of the...BIBLIOGRAPHY 1964 29 L. Collins, "Bendix Microvision ," Air Facts, 27, September 1964 30 T. Gold, Flight Control System, U. S. Patent No. 3,128,623, April...Lambert, "Head-Up Over the Hills," Flight International, 22 October 1964, pp. 709-713 35 C. H. Mattinson, "Formation Flying with Microvision ," U. S. Army

  12. [Tilt test for the evaluation of syncope of unknown origin].

    Science.gov (United States)

    Muratore, C; Rabinovich, R; Valentino, M; Baranchuk, A; Liprandi, A S

    1997-01-01

    The aim of this study was to evaluate the usefulness of head up tilt testing in patients with syncope of unknown origin. Between January 1994 and September 1995, 93 patients were referred for tilt table assessment due to recurrent syncope of uncertain etiology. There were 42 men (mean age 59 years). Thirty healthy volunteers served as a control group. The specific protocol used involved an initial period of supine rest for 15'. Baseline blood pressure (BP) and heart rate (HR) were recorded. This was followed by a tilt to 80 degrees for 30', BP and HR were measured every minute during the procedure. The test was considered positive when symptoms appeared associated with one of the following responses: systolic BP decreased more than 30 mmHg (vasodepressor), bradicardia or asystolia for up to 3" (cardioinhibitory) or mixed. The tilt test was positive in 31 of 93 patients (33%). Seventeen patients (55%) had a vasodepressor response, 3 patients (9%) a cardioinhibitory response and 11 patients (36%) mixed responses. The clinical manifestations were 62% near syncope, 19% syncope and the other patients presented dypsnea or dizziness. The symptoms disappeared promptly after adopting the supine position. None of the 30 healthy volunteers developed symptoms. We conclude that head up tilt test is a safe and effective method for identifying a neurocardiogenic origin in a syncope of uncertain etiology.

  13. Heads-Up Macular Surgery with a 27-Gauge Microincision Vitrectomy System and Minimal Illumination

    Directory of Open Access Journals (Sweden)

    Hiroshi Kunikata

    2016-11-01

    Full Text Available Objective: We combined heads-up 3-dimensional (3D 27-gauge microincision vitrectomy surgery (27GMIVS with a very low-intensity illumination system. Methods: This study was based on a retrospective, interventional case series of 6 eyes of 6 patients with macular disease. All patients underwent heads-up 3D 27GMIVS and the power of the intraocular illuminator was set to its minimum level, 1% (approximately 0.1 lm, throughout the surgery. Results: We found that the procedure was easy when the heads-up 3D system was used, but not through the eyepiece of a microscope. All surgeries were successfully finished without any complications. Postoperative visual acuity was restored or maintained in all eyes during the follow-up period. Conclusion: Heads-up, 3D system-assisted 27GMIVS with minimal illumination enabled excellent intraoperative visualization of retinal tissues, caused minimal phototoxicity to the macular retinal cells, and might therefore represent the next step in the development of an ideal, minimally invasive method of treating macular disease.

  14. A case of orthostatic tachycardia syndrome presenting with panic attack during tilt table testing.

    Science.gov (United States)

    Kataoka, H

    2011-01-01

    A 26-year-old woman experienced syncope on standing 2-3 times a year for more than 15 years. The attack was typically associated with palpitations and frequently accompanied by a feeling of intense fear. The patient underwent head-up tilt table testing at 70° for 40 min to determine the cause of the syncope. The tilt test results suggested that the etiology of the syncope was orthostatic tachycardia syndrome complicated by panic attack-associated hypocapnic hyperventilation, which presumably caused a greater degree of deep cerebral hypoperfusion than would be expected with orthostatic tachycardia syndrome alone, ultimately leading to the patient's symptoms, including syncope. In conclusion, monitoring the ventilation and/or arterial CO(2) level during head-up tilt table testing is occasionally required when evaluating patients with postural syncope. Copyright © 2011 S. Karger AG, Basel.

  15. Effects of Airport Tower Controller Decision Support Tool on Controllers Head-Up Time

    Science.gov (United States)

    Hayashi, Miwa; Cruz Lopez, Jose M.

    2013-01-01

    Despite that aircraft positions and movements can be easily monitored on the radar displays at major airports nowadays, it is still important for the air traffic control tower (ATCT) controllers to look outside the window as much as possible to assure safe operations of traffic management. The present paper investigates whether an introduction of the NASA's proposed Spot and Runway Departure Advisor (SARDA), a decision support tool for the ATCT controller, would increase or decrease the controllers' head-up time. SARDA provides the controller departure-release schedule advisories, i.e., when to release each departure aircraft in order to minimize individual aircraft's fuel consumption on taxiways and simultaneously maximize the overall runway throughput. The SARDA advisories were presented on electronic flight strips (EFS). To investigate effects on the head-up time, a human-in-the-loop simulation experiment with two retired ATCT controller participants was conducted in a high-fidelity ATCT cab simulator with 360-degree computer-generated out-the-window view. Each controller participant wore a wearable video camera on a side of their head with the camera facing forward. The video data were later used to calculate their line of sight at each moment and eventually identify their head-up times. Four sessions were run with the SARDA advisories, and four sessions were run without (baseline). Traffic-load levels were varied in each session. The same set of user interface - EFS and the radar displays - were used in both the advisory and baseline sessions to make them directly comparable. The paper reports the findings and discusses their implications.

  16. Advances and trends of head-up and head-down display systems in automobiles

    Science.gov (United States)

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

    2014-06-01

    Currently, in the automotive industry the interaction between drivers and Augmented Reality (AR) systems is a subject of analysis, especially the identification of advantages and risks that this kind of interaction represents. Consequently, this paper attempts to put in evidence the potential applications of Head-Up (Display (HUD) and Head-Down Display (HDD) systems in automotive vehicles, showing applications and trends under study. In general, automotive advances related to AR devices suggest the partial integration of the HUD and HDD in automobiles; however, the right way to do it is still a moot point.

  17. A user study of auditory, head-up and multi-modal displays in vehicles.

    Science.gov (United States)

    Jakus, Grega; Dicke, Christina; Sodnik, Jaka

    2015-01-01

    This paper describes a user study on the interaction with an in-vehicle information system (IVIS). The motivation for conducting this research was to investigate the subjectively and objectively measured impact of using a single- or multi-modal IVIS while driving. A hierarchical, list-based menu was presented using a windshield projection (head-up display), auditory display and a combination of both interfaces. The users were asked to navigate a vehicle in a driving simulator and simultaneously perform a set of tasks of varying complexity. The experiment showed that the interaction with visual and audio-visual head-up displays is faster and more efficient than with the audio-only display. All the interfaces had a similar impact on the overall driving performance. There was no significant difference between the visual only and audio-visual displays in terms of their efficiency and safety; however, the majority of test subjects clearly preferred to use the multi-modal interface while driving. Copyright © 2014 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  18. 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). Researc...

  19. Diagnosing postural tachycardia syndrome: comparison of tilt testing compared with standing haemodynamics.

    Science.gov (United States)

    Plash, Walker B; Diedrich, André; Biaggioni, Italo; Garland, Emily M; Paranjape, Sachin Y; Black, Bonnie K; Dupont, William D; Raj, Satish R

    2013-01-01

    POTS (postural tachycardia syndrome) is characterized by an increased heart rate (ΔHR) of ≥30 bpm (beats/min) with symptoms related to upright posture. Active stand (STAND) and passive head-up tilt (TILT) produce different physiological responses. We hypothesized these different responses would affect the ability of individuals to achieve the POTS HR increase criterion. Patients with POTS (n=15) and healthy controls (n=15) underwent 30 min of tilt and stand testing. ΔHR values were analysed at 5 min intervals. ROC (receiver operating characteristic) analysis was performed to determine optimal cut point values of ΔHR for both tilt and stand. Tilt produced larger ΔHR than stand for all 5 min intervals from 5 min (38±3 bpm compared with 33±3 bpm; P=0.03) to 30 min (51±3 bpm compared with 38±3 bpm; Pbpm criterion was similar for all tests (TILT10=93%, STAND10=87%, TILT30=100%, and STAND30=93%). Sp (specificity) of the 30 bpm criterion was less at both 10 and 30 min for tilt (TILT10=40%, TILT30=20%) than stand (STAND10=67%, STAND30=53%). The optimal ΔHR to discriminate POTS at 10 min were 38 bpm (TILT) and 29 bpm (STAND), and at 30 min were 47 bpm (TILT) and 34 bpm (STAND). Orthostatic tachycardia was greater for tilt (with lower Sp for POTS diagnosis) than stand at 10 and 30 min. The 30 bpm ΔHR criterion is not suitable for 30 min tilt. Diagnosis of POTS should consider orthostatic intolerance criteria and not be based solely on orthostatic tachycardia regardless of test used.

  20. Computer science. Heads-up limit hold'em poker is solved.

    Science.gov (United States)

    Bowling, Michael; Burch, Neil; Johanson, Michael; Tammelin, Oskari

    2015-01-09

    Poker is a family of games that exhibit imperfect information, where players do not have full knowledge of past events. Whereas many perfect-information games have been solved (e.g., Connect Four and checkers), no nontrivial imperfect-information game played competitively by humans has previously been solved. Here, we announce that heads-up limit Texas hold'em is now essentially weakly solved. Furthermore, this computation formally proves the common wisdom that the dealer in the game holds a substantial advantage. This result was enabled by a new algorithm, CFR(+), which is capable of solving extensive-form games orders of magnitude larger than previously possible. Copyright © 2015, American Association for the Advancement of Science.

  1. A head-up display for mid-air drone recovery

    Science.gov (United States)

    Augustine, W. L.; Heft, E. L.; Bowen, T. E.; Newman, R. L.

    1978-01-01

    During mid-air retrieval of parachute packages, the absence of a natural horizon creates serious difficulties for the pilot of the recovery helicopter. A head-up display (HUD) was tested in an attempt to solve this problem. Both a roll-stabilized HUD and a no-roll (pitch only) HUD were tested. The results show that fewer missed passes occurred with the roll-stabilized HUD when the horizon was obscured. The pilots also reported that the workload was greatly reduced. Roll-stabilization was required to prevent vertigo when flying in the absence of a natural horizon. Any HUD intended for mid-air retrieval should display pitch, roll, sideslip, airspeed, and vertical velocity.

  2. DeepStack: Expert-level artificial intelligence in heads-up no-limit poker.

    Science.gov (United States)

    Moravčík, Matej; Schmid, Martin; Burch, Neil; Lisý, Viliam; Morrill, Dustin; Bard, Nolan; Davis, Trevor; Waugh, Kevin; Johanson, Michael; Bowling, Michael

    2017-05-05

    Artificial intelligence has seen several breakthroughs in recent years, with games often serving as milestones. A common feature of these games is that players have perfect information. Poker, the quintessential game of imperfect information, is a long-standing challenge problem in artificial intelligence. We introduce DeepStack, an algorithm for imperfect-information settings. It combines recursive reasoning to handle information asymmetry, decomposition to focus computation on the relevant decision, and a form of intuition that is automatically learned from self-play using deep learning. In a study involving 44,000 hands of poker, DeepStack defeated, with statistical significance, professional poker players in heads-up no-limit Texas hold'em. The approach is theoretically sound and is shown to produce strategies that are more difficult to exploit than prior approaches. Copyright © 2017, American Association for the Advancement of Science.

  3. Integration of Head-Up Display system in automotive industry: a generalized application

    Science.gov (United States)

    Betancur, J. Alejandro; Osorio, Gilberto; Mejía, Alejandro

    2013-06-01

    Throughout the development of the automotive industry, supporting activities related with driving has been material of analysis and experimentation, always seeking new ways to achieve greater safety for the driver and passengers. With the purpose of contributing to this topic, in order to contribute to this subject, this paper summarizes from past research experiences the use of Head-Up Display systems applied to the automobile industry, covering it from two main points of discussion: the first one, from a technical point of view, in which the main principles of optical design associated with a moderate-cost experimental set up are brought out; and the second one, an operational approach where an applied driving graphical interface is presented. Up to now, the results suggest that the experimental set up here discussed could be adaptable to any automobile vehicle, but it is needed further research and investment.

  4. Tilt Table Test

    Science.gov (United States)

    ... pressure (the bottom number in a blood pressure reading), lowers peripheral vascular resistance, increases your heart rate ... mayoclinic.org/tests-procedures/tilt-table-test/basics/definition/PRC-20019879 . Mayo Clinic Footer Legal Conditions and ...

  5. Tilt-up construction

    OpenAIRE

    Crompton, Richard E.

    1992-01-01

    CIVINS Tilt-up construction is a special form of precast concrete construction. The technique is used for constructing buildings by prefabricating concrete wall sections (panels) in a horizontal position on either the building's floor slab or on a temporary casting slab. Once the wall sections have cured, they are tilted to a vertical position using a mobile crane, they are temporarily braced in their final upright position, and finally, they are tied into the building's roof and floor sys...

  6. Low cost heads-up virtual reality (HUVR) with optical tracking and haptic feedback

    Science.gov (United States)

    Margolis, Todd; DeFanti, Thomas A.; Dawe, Greg; Prudhomme, Andrew; Schulze, Jurgen P.; Cutchin, Steve

    2011-03-01

    Researchers at the University of California, San Diego, have created a new, relatively low-cost augmented reality system that enables users to touch the virtual environment they are immersed in. The Heads-Up Virtual Reality device (HUVR) couples a consumer 3D HD flat screen TV with a half-silvered mirror to project any graphic image onto the user's hands and into the space surrounding them. With his or her head position optically tracked to generate the correct perspective view, the user maneuvers a force-feedback (haptic) device to interact with the 3D image, literally 'touching' the object's angles and contours as if it was a tangible physical object. HUVR can be used for training and education in structural and mechanical engineering, archaeology and medicine as well as other tasks that require hand-eye coordination. One of the most unique characteristics of HUVR is that a user can place their hands inside of the virtual environment without occluding the 3D image. Built using open-source software and consumer level hardware, HUVR offers users a tactile experience in an immersive environment that is functional, affordable and scalable.

  7. High brightness MEMS mirror based head-up display (HUD) modules with wireless data streaming capability

    Science.gov (United States)

    Milanovic, Veljko; Kasturi, Abhishek; Hachtel, Volker

    2015-02-01

    A high brightness Head-Up Display (HUD) module was demonstrated with a fast, dual-axis MEMS mirror that displays vector images and text, utilizing its ~8kHz bandwidth on both axes. Two methodologies were evaluated: in one, the mirror steers a laser at wide angles of shelf lenses and a MEMS mirror in combination with a MEMS controller to enable precise movement of the mirror's X- and Y-axis. The MEMS controller offers both USB and wireless streaming capability and we utilize a library of functions on a host computer for creating content and controlling the mirror. Integration with smart phone applications is demonstrated, utilizing the mobile device both for content generation based on various messages or data, and for content streaming to the MEMS controller via Bluetooth interface. The display unit is highly resistant to vibrations and shock, and requires only ~1.5W to operate, even with content readable in sunlit outdoor conditions. The low power requirement is in part due to a vector graphics approach, allowing the efficient use of laser power, and also due to the use of a single, relatively high efficiency laser and simple optics.

  8. Novel microscope-integrated stereoscopic heads-up display for intrasurgical optical coherence tomography.

    Science.gov (United States)

    Shen, Liangbo; Carrasco-Zevallos, Oscar; Keller, Brenton; Viehland, Christian; Waterman, Gar; Hahn, Paul S; Kuo, Anthony N; Toth, Cynthia A; Izatt, Joseph A

    2016-05-01

    Intra-operative optical coherence tomography (OCT) requires a display technology which allows surgeons to visualize OCT data without disrupting surgery. Previous research and commercial intrasurgical OCT systems have integrated heads-up display (HUD) systems into surgical microscopes to provide monoscopic viewing of OCT data through one microscope ocular. To take full advantage of our previously reported real-time volumetric microscope-integrated OCT (4D MIOCT) system, we describe a stereoscopic HUD which projects a stereo pair of OCT volume renderings into both oculars simultaneously. The stereoscopic HUD uses a novel optical design employing spatial multiplexing to project dual OCT volume renderings utilizing a single micro-display. The optical performance of the surgical microscope with the HUD was quantitatively characterized and the addition of the HUD was found not to substantially effect the resolution, field of view, or pincushion distortion of the operating microscope. In a pilot depth perception subject study, five ophthalmic surgeons completed a pre-set dexterity task with 50.0% (SD = 37.3%) higher success rate and in 35.0% (SD = 24.8%) less time on average with stereoscopic OCT vision compared to monoscopic OCT vision. Preliminary experience using the HUD in 40 vitreo-retinal human surgeries by five ophthalmic surgeons is reported, in which all surgeons reported that the HUD did not alter their normal view of surgery and that live surgical maneuvers were readily visible in displayed stereoscopic OCT volumes.

  9. Low cost heads-up virtual reality (HUVR) with optical tracking and haptic feedback

    KAUST Repository

    Margolis, Todd

    2011-01-23

    Researchers at the University of California, San Diego, have created a new, relatively low-cost augmented reality system that enables users to touch the virtual environment they are immersed in. The Heads-Up Virtual Reality device (HUVR) couples a consumer 3D HD flat screen TV with a half-silvered mirror to project any graphic image onto the user\\'s hands and into the space surrounding them. With his or her head position optically tracked to generate the correct perspective view, the user maneuvers a force-feedback (haptic) device to interact with the 3D image, literally \\'touching\\' the object\\'s angles and contours as if it was a tangible physical object. HUVR can be used for training and education in structural and mechanical engineering, archaeology and medicine as well as other tasks that require hand-eye coordination. One of the most unique characteristics of HUVR is that a user can place their hands inside of the virtual environment without occluding the 3D image. Built using open-source software and consumer level hardware, HUVR offers users a tactile experience in an immersive environment that is functional, affordable and scalable.

  10. Prueba de inclinación (“Head-up Tilt Test”), lecciones aprendidas en 564 casos consecutivos: Lessons Learned from 564 Consecutive Cases

    OpenAIRE

    Oswaldo Gutiérrez-Sotelo; Yorleny Alfaro-Badilla

    2012-01-01

    Introducción. El síncope es un motivo frecuente de consulta; el mecanismo causal más común es el reflejo, que incluye el síncope neurocardiogénico (SN), la hipotensión ortostática, la hipersensibilidad del seno carotídeo, entre otros. Estas variantes se valoran mediante la prueba de inclinación, con o sin estímulo farmacológico con nitroglicerina. El presente estudio recoge la experiencia con este examen auxiliar realizado en nuestro centro en los últimos 8 años. Material y métodos. Es un est...

  11. Reduced systemic vascular resistance is the underlying hemodynamic mechanism in nitrate-stimulated vasovagal syncope during head-up tilt-table test

    Directory of Open Access Journals (Sweden)

    Byung Gyu Kim, MD

    2015-08-01

    Conclusions: Presyncopal symptoms during NTG-stimulated HUTT are SVR mediated, not cardiac output mediated. This study challenges the conventional idea of a decrease in cardiac output mediated by NTG as the overriding cause of presyncopal symptoms during HUTT.

  12. Pulsed Wave Doppler Ultrasound Is Useful to Assess Vasomotor Response in Patients with Multiple System Atrophy and Well Correlated with Tilt Table Study

    Directory of Open Access Journals (Sweden)

    Ke-Vin Chang

    2012-01-01

    Full Text Available The study aim was to assess sympathetic vasomotor response (SVR by using pulsed wave Doppler (PWD ultrasound in patients with multiple system atrophy (MSA and correlate with the tilt table study. We recruited 18 male patients and 10 healthy men as controls. The SVR of the radial artery was evaluated by PWD, using inspiratory cough as a provocative maneuver. The response to head-up tilt was studied by a tilt table with simultaneous heart rate and blood pressure recording. The hemodynamic variables were compared between groups, and were examined by correlation analysis. Regarding SVR, MSA patients exhibited a prolonged latency and less heart rate acceleration following inspiratory cough. Compared with the tilt table test, the elevation of heart rate upon SVR was positively correlated to the increase of heart rate after head-up tilt. The correlation analysis indicated that the magnitude of blood pressure drop from supine to upright was positively associated with the SVR latency but negatively correlated with the heart rate changes upon SVR. The present study demonstrated that blunted heart rate response might explain MSA's vulnerability to postural challenge. PWD may be used to predict cardiovascular response to orthostatic stress upon head-up tilt in MSA patients.

  13. A study to evaluate STS heads-up ascent trajectory performance employing a minimum-Hamiltonian optimization strategy

    Science.gov (United States)

    Sinha, Sujit

    1988-01-01

    A study was conducted to evaluate the performance implications of a heads-up ascent flight design for the Space Transportation System, as compared to the current heads-down flight mode. The procedure involved the use of the Minimum Hamiltonian Ascent Shuttle Trajectory Evaluation Program, which is a three-degree-of-freedom moment balance simulation of shuttle ascent. A minimum-Hamiltonian optimization strategy was employed to maximize injection weight as a function of maximum dynamic pressure constraint and Solid Rocket Motor burnrate. Performance Reference Mission Four trajectory groundrules were used for consistency. The major conclusions are that for heads-up ascent and a mission nominal design maximum dynamic pressure value of 680 psf, the optimum solid motor burnrate is 0.394 ips, which produces a performance enhancement of 4293 lbm relative to the baseline heads-down ascent, with 0.368 ips burnrate solid motors and a 680 psf dynamic pressure constraint. However, no performance advantage exists for heads-up flight if the current Solid Rocket Motor target burnrate of 0.368 ips is used. The advantage of heads-up ascent flight employing the current burnrate is that Space Shuttle Main Engine throttling for dynamic pressure control is not necessary.

  14. Navigation-Linked Heads-Up Display in Intracranial Surgery: Early Experience.

    Science.gov (United States)

    Mascitelli, Justin R; Schlachter, Leslie; Chartrain, Alexander G; Oemke, Holly; Gilligan, Jeffrey; Costa, Anthony B; Shrivastava, Raj K; Bederson, Joshua B

    2017-10-10

    The use of intraoperative navigation during microscope cases can be limited when attention needs to be divided between the operative field and the navigation screens. Heads-up display (HUD), also referred to as augmented reality, permits visualization of navigation information during surgery workflow. To detail our initial experience with HUD. We retrospectively reviewed patients who underwent HUD-assisted surgery from April 2016 through April 2017. All lesions were assessed for accuracy and those from the latter half of the study were assessed for utility. Seventy-nine patients with 84 pathologies were included. Pathologies included aneurysms (14), arteriovenous malformations (6), cavernous malformations (5), intracranial stenosis (3), meningiomas (27), metastasis (4), craniopharygniomas (4), gliomas (4), schwannomas (3), epidermoid/dermoids (3), pituitary adenomas (2) hemangioblastoma (2), choroid plexus papilloma (1), lymphoma (1), osteoblastoma (1), clival chordoma (1), cerebrospinal fluid leak (1), abscess (1), and a cerebellopontine angle Teflon granuloma (1). Fifty-nine lesions were deep and 25 were superficial. Structures identified included the lesion (81), vessels (48), and nerves/brain tissue (31). Accuracy was deemed excellent (71.4%), good (20.2%), or poor (8.3%). Deep lesions were less likely to have excellent accuracy (P = .029). HUD was used during bed/head positioning (50.0%), skin incision (17.3%), craniotomy (23.1%), dural opening (26.9%), corticectomy (13.5%), arachnoid opening (36.5%), and intracranial drilling (13.5%). HUD was deactivated at some point during the surgery in 59.6% of cases. There were no complications related to HUD use. HUD can be safely used for a wide variety of vascular and oncologic intracranial pathologies and can be utilized during multiple stages of surgery.

  15. Real-time Video-Streaming to Surgical Loupe Mounted Head-Up Display for Navigated Meningioma Resection.

    Science.gov (United States)

    Diaz, Roberto; Yoon, Jang; Chen, Robert; Quinones-Hinojosa, Alfredo; Wharen, Robert; Komotar, Ricardo

    2017-04-30

    Wearable technology interfaces with normal human movement and function, thereby enabling more efficient and adaptable use.We developed a wearable display system for use with intra-operative neuronavigation for brain tumor surgery. The Google glass head-up display system was adapted to surgical loupes with a video-streaming integrated hardware and software device for display of the Stealth S7 navigation screen. Phantom trials of surface ventriculostomy were performed. The device was utilized as an alternative display screen during cranial surgery. Image-guided brain tumor resection was accomplished using Google Glass head-up display of Stealth S7 navigation images. Visual display consists of navigation video-streaming over a wireless network. The integrated system developed for video-streaming permits video data display to the operating surgeon without requiring movement of the head away from the operative field. Google Glass head-up display can be used for intra-operative neuronavigation in the setting of intracranial tumor resection.

  16. Impaired cerebral autoregulation during upright tilt in patients with severe brain injury

    DEFF Research Database (Denmark)

    Hansen, Christian Riberholt; Olesen, Niels; Thing, Mira

    ) and the CBFV were lower in the patients (p increase in the Mxc index during head-up tilt pointing at impaired autoregulation (p = 0.001). Spectral analysis of HR variability in the frequency domain revealed significant lower magnitudes of ~ 0.1 Hz spectral power......Objectives: Upright tilt is an important tool for early mobilization of patients after severe acquired brain injury (ABI). Early mobilization is considered to be of importance for increasing awareness, in the prevention of contractures and pulmonary infections and to improve long-term outcome....... A challenge for early mobilization is orthostatic instability that is often observed during heap-up tilt, which could lead to decreased cerebral blood flow velocity (CBFV) and decreased long-term outcome. We examined cerebral blood flow autoregulation in patients with severe brain injury and impaired...

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

    Science.gov (United States)

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

    1994-01-01

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

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

    Science.gov (United States)

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

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

  19. 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

  20. Evaluating Tilt for Wind Plants

    Energy Technology Data Exchange (ETDEWEB)

    Annoni, Jennifer [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Scholbrock, Andrew K. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Churchfield, Matthew J. [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Fleming, Paul A. [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-07-03

    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 three-turbine 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.

  1. Effect of background scene complexity and field dependence on the legibility of head-up displays for automotive applications.

    Science.gov (United States)

    Ward, N J; Parkes, A; Crone, P R

    1995-12-01

    This study examined the legibility of information presented on head-up displays (HUDs) for automotive application as a function of background scene complexity, the position of the HUD within field of view relative to the background scene, and the perceptual capacity of the perceiver. Groups of field-dependent and field-independent subjects viewed video footage from the perspective of following a lead car on an open road with low, moderate, and high scene complexity. Subjects were required to track the lead vehicle and identify HUD-presented targets of a specified orientation and specified changes in a HUD-presented speedometer. The results indicate that (a) HUD legibility deteriorated with increased visual complexity of the background scene; (b) positioning the HUD on the roadway reduced the effect of background scene complexity on HUD legibility; and (c) field-dependent subjects made fewer correct and more false positive target identifications than did field-independent subjects.

  2. Human responses to upright tilt: a window on central autonomic integration

    Science.gov (United States)

    Cooke, W. H.; Hoag, J. B.; Crossman, A. A.; Kuusela, T. A.; Tahvanainen, K. U.; Eckberg, D. L.

    1999-01-01

    1. We examined interactions between haemodynamic and autonomic neural oscillations during passive upright tilt, to gain better insight into human autonomic regulatory mechanisms. 2. We recorded the electrocardiogram, finger photoplethysmographic arterial pressure, respiration and peroneal nerve muscle sympathetic activity in nine healthy young adults. Subjects breathed in time with a metronome at 12 breaths min-1 (0.2 Hz) for 5 min each, in supine, and 20, 40, 60, 70 and 80 deg head-up positions. We performed fast Fourier transform (and autoregressive) power spectral analyses and integrated low-frequency (0.05-0.15 Hz) and respiratory-frequency (0. 15-0.5 Hz) spectral powers. 3. Integrated areas of muscle sympathetic bursts and their low- and respiratory-frequency spectral powers increased directly and significantly with the tilt angle. The centre frequency of low-frequency sympathetic oscillations was constant before and during tilt. Sympathetic bursts occurred more commonly during expiration than inspiration at low tilt angles, but occurred equally in expiration and inspiration at high tilt angles. 4. Systolic and diastolic pressures and their low- and respiratory-frequency spectral powers increased, and R-R intervals and their respiratory-frequency spectral power decreased progressively with the tilt angle. Low-frequency R-R interval spectral power did not change. 5. The cross-spectral phase angle between systolic pressures and R-R intervals remained constant and consistently negative at the low frequency, but shifted progressively from positive to negative at the respiratory frequency during tilt. The arterial baroreflex modulus, calculated from low-frequency cross-spectra, decreased at high tilt angles. 6. Our results document changes of baroreflex responses during upright tilt, which may reflect leftward movement of subjects on their arterial pressure sympathetic and vagal response relations. The intensity, but not the centre frequency of low

  3. Evaluation of a Head-Worn Display System as an Equivalent Head-Up Display for Low Visibility Commercial Operations

    Science.gov (United States)

    Arthur, Jarvis (Trey) J., III; Shelton, Kevin J.; Prinzel, Lawrence J.; Nicholas, Stephanie N.; Williams, Steven P.; Ellis, Kyle E.; Jones, Denise R.; Bailey, Randall E.; Harrison, Stephanie J.; Barnes, James R.

    2017-01-01

    Research, development, test, and evaluation of fight deck interface technologies is being conducted by the National Aeronautics and Space Administration (NASA) to proactively identify, develop, and mature tools, methods, and technologies for improving overall aircraft safety of new and legacy vehicles operating in the Next Generation Air Transportation System (NextGen). One specific area of research was the use of small Head-Worn Displays (HWDs) to serve as a possible equivalent to a Head-Up Display (HUD). A simulation experiment and a fight test were conducted to evaluate if the HWD can provide an equivalent level of performance to a HUD. For the simulation experiment, airline crews conducted simulated approach and landing, taxi, and departure operations during low visibility operations. In a follow-on fight test, highly experienced test pilots evaluated the same HWD during approach and surface operations. The results for both the simulation and fight tests showed that there were no statistical differences in the crews' performance in terms of approach, touchdown and takeoff; but, there are still technical hurdles to be overcome for complete display equivalence including, most notably, the end-to-end latency of the HWD system.

  4. 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.

  5. A heads-up no-limit Texas Hold'em poker player: Discretized betting models and automatically generated equilibrium-finding programs

    DEFF Research Database (Denmark)

    Gilpin, Andrew G.; Sandholm, Tuomas; Sørensen, Troels Bjerre

    2008-01-01

    We present Tartanian, a game theory-based player for heads-up no-limit Texas Hold'em poker. Tartanian is built from three components. First, to deal with the virtually infinite strategy space of no-limit poker, we develop a discretized betting model designed to capture the most important strategic...

  6. Broad-band green phosphor screens as a light source for head up displays in moving platforms

    Science.gov (United States)

    Silver, Jack; Withnall, Robert; Rose, John; Wilstead, Nicola; Fern, George; Bishton, Stephen; Klein, David; Rhodes, Bob; Barclay, Charles; Whitmarsh, John

    2005-06-01

    A broad-band green light source for a head-up display is presented. To our knowledge, this is the first report of a green phosphor screen being excited by a blue LED as a backlight for monochrome HUDs. The phosphor screen not only generates the green light but it acts as a diffuser to give a homogeneous illumination. A microlens array focuses the emissions from LED sources on to the diffusing screen eliminating halo effects from the individual LEDs. The purpose of using a green phosphor is to exploit the fact that the eye is sensitive to more shades of green than any other colour. In uses where there are elements of danger such as automobiles (in busy areas), vehicles on construction sites and military vehicles in war zones, green displays have obvious attractions. This paper presents a discussion of the green phosphors that can be used in green screen fabrication, the deposition of the phosphor powders on the screens, the influence of the thickness of the phosphor powder on the screen brightness. In addition, the factors that influence the CIE coordinates of the light emitted from the screen are considered. The importance of choosing the optimum LED emission wavelength along with the general construction of the HUD is discussed. The merits of using a green screen are compared to those when using full colour displays based on white phosphor screens in which yellow emitting phosphors are excited by blue LEDs. Heat management in these HUD devices is achieved by pulsing the LEDs and rastering rows within the LED array.

  7. Cerebral Blood Flow, Heart Rate, and Blood Pressure Patterns during the Tilt Test in Common Orthostatic Syndromes

    Directory of Open Access Journals (Sweden)

    Peter Novak

    2016-01-01

    Full Text Available Objective. The head-up tilt test is widely used for evaluation of orthostatic intolerance. Although orthostatic symptoms usually reflect cerebral hypoperfusion, the cerebral blood flow velocity (CBFv profile in orthostatic syndromes is not well described. This study evaluated CBFv and cardiovascular patterns associated with the tilt test in common orthostatic syndromes. Methods. This retrospective study analyzed the tilt test of patients with history of orthostatic intolerance. The following signals were recorded: ECG, blood pressure, CBFv using transcranial Doppler, respiratory signals, and end tidal CO2. Results. Data from 744 patients were analyzed. Characteristic pattern associated with a particular orthostatic syndrome can be grouped into abnormalities predominantly affecting blood pressure (orthostatic hypotension, orthostatic hypertension syndrome, vasomotor oscillations, and neurally mediated syncope—cardioinhibitory, vasodepressor, and mixed, cerebral blood flow (orthostatic hypoperfusion syndrome, primary cerebral autoregulatory failure, and heart rate (tachycardia syndromes: postural tachycardia syndrome, paroxysmal sinus tachycardia, and inappropriate sinus tachycardia. Psychogenic pseudosyncope is associated with stable CBFv. Conclusions. The tilt test is useful add-on in diagnosis of several orthostatic syndromes. However diagnostic criteria for several syndromes had to be modified to allow unambiguous pattern classification. CBFv monitoring in addition to blood pressure and heart rate may increase diagnostic yield of the tilt test.

  8. Comparison of Indiana High School Football Injury Rates by Inclusion of the USA Football "Heads Up Football" Player Safety Coach.

    Science.gov (United States)

    Kerr, Zachary Y; Dalton, Sara L; Roos, Karen G; Djoko, Aristarque; Phelps, Jennifer; Dompier, Thomas P

    2016-05-01

    In Indiana, high school football coaches are required to complete a coaching education course with material related to concussion awareness, equipment fitting, heat emergency preparedness, and proper technique. Some high schools have also opted to implement a player safety coach (PSC). The PSC, an integral component of USA Football's Heads Up Football (HUF) program, is a coach whose primary responsibility is to ensure that other coaches are implementing proper tackling and blocking techniques alongside other components of the HUF program. To compare injury rates in Indiana high school football teams by their usage of a PSC or online coaching education only. Cohort study; Level of evidence, 2. Athletic trainers (ATs) evaluated and tracked injuries at each practice and game during the 2015 high school football season. Players were drawn from 6 teams in Indiana. The PSC group, which used the PSC component, was comprised of 204 players from 3 teams. The "education only" group (EDU), which utilized coaching education only, was composed of 186 players from 3 teams. Injury rates and injury rate ratios (IRRs) were reported with 95% confidence intervals (CIs). During 25,938 athlete-exposures (AEs), a total of 149 injuries were reported, of which 54 (36.2%) and 95 (63.8%) originated from the PSC and EDU groups, respectively. The practice injury rate was lower in the PSC group than the EDU group (2.99 vs 4.83/1000 AEs; IRR, 0.62; 95% CI, 0.40-0.95). The game injury rate was also lower in the PSC group than the EDU group (11.37 vs 26.37/1000 AEs; IRR, 0.43; 95% CI, 0.25-0.74). When restricted to concussions only, the rate was lower in the PSC group (0.09 vs 0.73/1000 AEs; IRR, 0.12; 95% CI, 0.01-0.94), although only 1 concussion was reported in the PSC group. No differences were found in game concussion rates (0.60 vs 4.39/1000 AEs; IRR, 0.14; 95% CI, 0.02-1.11). Findings support the PSC as an effective method of injury mitigation in high school football. Future research

  9. Height and Tilt Geometric Texture

    DEFF Research Database (Denmark)

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

    2009-01-01

    We propose a new intrinsic representation of geometric texture over triangle meshes. Our approach extends the conventional height field texture representation by incorporating displacements in the tangential plane in the form of a normal tilt. This texture representation offers a good practical...... 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...... texture editing and animation (such as bending or waving) intuitively controllable over arbitrary base mesh. We also provide simple methods for texture extraction and transfer using our height-and-field representation....

  10. Tilt-table testing of patients with pacemaker and recurrent syncope

    DEFF Research Database (Denmark)

    Nielsen, Christian E. Haarmark; Kanters, Jørgen K; Mehlsen, Jesper

    2016-01-01

    responses accounting for 72% of patients with a positive test. There were no differences between groups with positive or negative test result regarding age, gender, resting blood pressure and heart rate, daily fluid intake, pacing mode, pacing indication or pacing rhythm at rest. HUT in patients......The diagnosis of recurrent syncope in patients with pacemakers (PM) is quite challenging and the etiology of syncope is often multifactorial. To portray the mechanism of syncope in PM patients, we report the results of head-up tilt table testing (HUT) in a series of patients with PM, originally...... implanted for reasons other than neurally mediated syncope, referred due to syncope or pre-syncope (aborted syncope, vertigo, suspected orthostatic hypotension). Forty-one patients with PM undergoing a HUT in our syncope unit between January 1st, 2007 and December 31st 2011 were included. A standard HUT...

  11. 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.

  12. A Control Method for Hybrid Tilting Systems using Tilting Beams and Air Spring Inclination

    National Research Council Canada - National Science Library

    KAMOSHITA, Shogo; SASAKI, Kimiaki; KAKINUMA, Hirohiko; SATO, Iwao; SATO, Yorimitsu; NAKAGAKI, Satoko

    2007-01-01

    .... The system coordinates tilting beams and a controlled air spring height, thus reducing losses in wheel-load and avoiding lateral displacement of the car body caused by the larger tilting angle...

  13. Estimation of beat-to-beat changes in stroke volume from arterial pressure: a comparison of two pressure wave analysis techniques during head-up tilt testing in young, healthy men

    NARCIS (Netherlands)

    Jellema, W. T.; Imholz, B. P.; Oosting, H.; Wesseling, K. H.; van Lieshout, J. J.

    1999-01-01

    OBJECTIVE: The aim of this study was to compare beat-to-beat changes in stroke volume (SV) estimated by two different pressure wave analysis techniques during orthostatic stress testing: pulse contour analysis and Modelflow, i.e., simulation of a three-element model of aortic input impedance.

  14. Estimation of beat-to-beat changes in stroke volume from arterial pressure: A comparison of two pressure wave analysis techniques during head- up tilt testing in young, healthy men

    NARCIS (Netherlands)

    Jellema, W.T.; Imholz, B.P.M.; Oosting, H.; Wesseling, K.H.; Lieshout, J.J. van

    1999-01-01

    Objective: The aim of this study was to compare beat-to-beat changes in stroke volume (SV) estimated by two different pressure wave analysis techniques during orthostatic stress testing: pulse contour analysis and Modelflow, ie, simulation of a three-element model of aortic input impedance. Methods:

  15. Driving While Interacting With Google Glass: Investigating the Combined Effect of Head-Up Display and Hands-Free Input on Driving Safety and Multitask Performance.

    Science.gov (United States)

    Tippey, Kathryn G; Sivaraj, Elayaraj; Ferris, Thomas K

    2017-06-01

    This study evaluated the individual and combined effects of voice (vs. manual) input and head-up (vs. head-down) display in a driving and device interaction task. Advances in wearable technology offer new possibilities for in-vehicle interaction but also present new challenges for managing driver attention and regulating device usage in vehicles. This research investigated how driving performance is affected by interface characteristics of devices used for concurrent secondary tasks. A positive impact on driving performance was expected when devices included voice-to-text functionality (reducing demand for visual and manual resources) and a head-up display (HUD) (supporting greater visibility of the driving environment). Driver behavior and performance was compared in a texting-while-driving task set during a driving simulation. The texting task was completed with and without voice-to-text using a smartphone and with voice-to-text using Google Glass's HUD. Driving task performance degraded with the addition of the secondary texting task. However, voice-to-text input supported relatively better performance in both driving and texting tasks compared to using manual entry. HUD functionality further improved driving performance compared to conditions using a smartphone and often was not significantly worse than performance without the texting task. This study suggests that despite the performance costs of texting-while-driving, voice input methods improve performance over manual entry, and head-up displays may further extend those performance benefits. This study can inform designers and potential users of wearable technologies as well as policymakers tasked with regulating the use of these technologies while driving.

  16. 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.

  17. 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

  18. Large optics inspection, tilting, and washing stand

    Science.gov (United States)

    Ayers, Marion Jay; Ayers, Shannon Lee

    2012-10-09

    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.

  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. Sensor fusion for structural tilt estimation using an acceleration-based tilt sensor and a gyroscope

    Science.gov (United States)

    Liu, Cheng; Park, Jong-Woong; Spencer, B. F., Jr.; Moon, Do-Soo; Fan, Jiansheng

    2017-10-01

    A tilt sensor can provide useful information regarding the health of structural systems. Most existing tilt sensors are gravity/acceleration based and can provide accurate measurements of static responses. However, for dynamic tilt, acceleration can dramatically affect the measured responses due to crosstalk. Thus, dynamic tilt measurement is still a challenging problem. One option is to integrate the output of a gyroscope sensor, which measures the angular velocity, to obtain the tilt; however, problems arise because the low-frequency sensitivity of the gyroscope is poor. This paper proposes a new approach to dynamic tilt measurements, fusing together information from a MEMS-based gyroscope and an acceleration-based tilt sensor. The gyroscope provides good estimates of the tilt at higher frequencies, whereas the acceleration measurements are used to estimate the tilt at lower frequencies. The Tikhonov regularization approach is employed to fuse these measurements together and overcome the ill-posed nature of the problem. The solution is carried out in the frequency domain and then implemented in the time domain using FIR filters to ensure stability. The proposed method is validated numerically and experimentally to show that it performs well in estimating both the pseudo-static and dynamic tilt measurements.

  1. Spin transport in tilted electron vortex beams

    OpenAIRE

    Basu, Banasri; Chowdhury, Debashree

    2016-01-01

    In this paper we have enlightened the spin related issues of tilted Electron vortex beams. We have shown that in the skyrmionic model of electron we can have the spin Hall current considering the tilted type of electron vortex beam. We have considered the monopole charge of the tilted vortex as time dependent and through the time variation of the monopole charge we can explain the spin Hall effect of electron vortex beams. Besides, with an external magnetic field we can have a spin filter con...

  2. METALLURGICAL ADVANTAGES OF ROTATION TILTING FURNACES

    Directory of Open Access Journals (Sweden)

    S. L. Rovin

    2010-01-01

    Full Text Available It is shown that introduction of rotary tilting furnaces can be a basis for considerable resources saving, lowering of power inputs, reduction of products cost for Byelorussian machine-building enterprises.

  3. Conservative treatment of excessive anterior pelvic tilt

    DEFF Research Database (Denmark)

    Brekke, Anders Falk

    , DK-5000 Odense C, Denmark ABSTRACT (1795 anslag) Background: Excessive anterior pelvic tilt has been linked to pain and dysfunction of the hip and pelvic region. Conservative treatment (e.g. manual therapy and physical training) is suggested in correcting the tilt and eventually related symptoms...... demonstrated a significant reduction in anterior pelvic tilt. The two studies intervening on symptomatic subjects demonstrated a significant reduction in pain and disability, respectively. Conclusions: Very low quality of evidence suggests that further studies are needed to clarify whether conservative......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...

  4. Study of mine stability using records of ground tilting

    CSIR Research Space (South Africa)

    Spottiswoode, SM

    2006-06-01

    Full Text Available ; the total amount of coseismic tilt in each direction is approximately the same; the time-of-day tilting shows the effect of blasting on the coseismic tilting and, to a lesser degree, on aseismic tilting. As a preliminary interpretation, this can...

  5. On-track test of tilt control strategies for less motion sickness on tilting trains

    Science.gov (United States)

    Persson, Rickard; Kufver, Björn; Berg, Mats

    2012-07-01

    Carbody tilting is today a mature and inexpensive technology that permits higher train speeds in horizontal curves, thus shortening travel time. However, tilting trains run a greater risk of causing motion sickness than non-tilting ones. It is likely that the difference in motions between the two train types contributes to the observed difference in risk of motion sickness. Decreasing the risk of motion sickness has until now been equal to increasing the discomfort related to quasi-static lateral acceleration. But, there is a difference in time perception between discomfort caused by quasi-static quantities and motion sickness, which opens up for new solutions. One proposed strategy is to let the local track conditions influence the tilt and give each curve its own optimised tilt angle. This is made possible by new tilt algorithms, storing track data and using a positioning system to select the appropriate data. The present paper reports from on-track tests involving more than 100 test subjects onboard a tilting train. A technical approach is taken evaluating the effectiveness of the new tilt algorithms and the different requirements on quasi-static lateral acceleration and lateral jerk in relative terms. The evaluation verifies that the rms values important for motion sickness can be influenced without changing the requirements on quasi-static lateral acceleration and lateral jerk. The evaluation shows that reduced quantities of motions assumed to have a relation to motion sickness also lead to a reduction in experienced motion sickness. However, a limitation of applicability is found as the lowest risk of motion sickness was not recorded for the test case with motions closest to those of a non-tilting train. An optimal level of tilt, different from no tilt at all, is obtained. This non-linear relation has been observed by other researchers in laboratory tests.

  6. Effect of age and gender on sudomotor and cardiovagal function and blood pressure response to tilt in normal subjects

    Science.gov (United States)

    Low, P. A.; Denq, J. C.; Opfer-Gehrking, T. L.; Dyck, P. J.; O'Brien, P. C.; Slezak, J. M.

    1997-01-01

    Normative data are limited on autonomic function tests, especially beyond age 60 years. We therefore evaluated these tests in a total of 557 normal subjects evenly distributed by age and gender from 10 to 83 years. Heart rate (HR) response to deep breathing fell with increasing age. Valsalva ratio varied with both age and gender. QSART (quantitative sudomotor axon-reflex test) volume was consistently greater in men (approximately double) and progressively declined with age for all three lower extremity sites but not the forearm site. Orthostatic blood pressure reduction was greater with increasing age. HR at rest was significantly higher in women, and the increment with head-up tilt fell with increasing age. For no tests did we find a regression to zero, and some tests seem to level off with increasing age, indicating that diagnosis of autonomic failure was possible to over 80 years of age.

  7. Heads Up: Keep Sports Safe.

    Science.gov (United States)

    Rice, Stephen G.

    1984-01-01

    Outlines standards in seven areas--staff training, facilities, athletic equipment, emergency preparedness, a central training room, athletic health care and training, and recordkeeping--for assessing school athletic programs so that potential injuries and lawsuits can be avoided. (KS)

  8. Tilt assembly for tracking solar collector assembly

    Science.gov (United States)

    Almy, Charles; Peurach, John; Sandler, Reuben

    2012-01-24

    A tilt assembly is used with a solar collector assembly of the type comprising a frame, supporting a solar collector, for movement about a tilt axis by pivoting a drive element between first and second orientations. The tilt assembly comprises a drive element coupler connected to the drive element and a driver, the driver comprising a drive frame, a drive arm and a drive arm driver. The drive arm is mounted to the drive frame for pivotal movement about a drive arm axis. Movement on the drive arm mimics movement of the drive element. Drive element couplers can extend in opposite directions from the outer portion of the drive arm, whereby the assembly can be used between adjacent solar collector assemblies in a row of solar collector assemblies.

  9. Reverse breech extraction versus the standard approach of pushing the impacted fetal head up through the vagina in caesarean section for obstructed labour: A randomised controlled trial.

    Science.gov (United States)

    Nooh, Ahmed Mohamed; Abdeldayem, Hussein Mohammed; Ben-Affan, Othman

    2017-05-01

    The objective of this study was to assess effectiveness and safety of the reverse breech extraction approach in Caesarean section for obstructed labour, and compare it with the standard approach of pushing the fetal head up through the vagina. This randomised controlled trial included 192 women. In 96, the baby was delivered by the 'reverse breech extraction approach', and in the remaining 96, by the 'standard approach'. Extension of uterine incision occurred in 18 participants (18.8%) in the reverse breech extraction approach group, and 46 (47.9%) in the standard approach group (p = .0003). Two women (2.1%) in the reverse breech extraction approach group needed blood transfusion and 11 (11.5%) in the standard approach group (p = .012). Pyrexia developed in 3 participants (3.1%) in the reverse breech extraction approach group, and 19 (19.8%) in the standard approach group (p = .0006). Wound infection occurred in 2 women (2.1%) in the reverse breech extraction approach group, and 12 (12.5%) in the standard approach group (p = .007). Apgar score vagina.

  10. Impact of EUV SRAF on Bossung tilt

    Science.gov (United States)

    Wang, Yow-Gwo; Hsu, Stephen; Socha, Robert; Neureuther, Andy; Naulleau, Patrick

    2017-03-01

    Mask 3D (M3D) effects remain a significant challenge affecting EUV lithography (EUVL) imaging performance due to the comparable sizes of the mask and the EUV wavelength. Pre-compensation with the insertion of sub-resolution assist features (SRAFs) has been proposed as a solution to compensate M3D effects and improve the process window for advanced technology nodes. In this paper, we discuss the possible positive impact of SRAFs on Bossung tilt, and provide physical insight into the optical mechanisms at play enabling M3D effect mitigation. In particular, we consider an example isolated 2-bar (CD = 16 nm) pattern imaged under delta function dipole illumination. We compare the scattered order distribution and Bossung tilt with and without SRAFs. The results show that SRAFs actually introduce stronger effective single pole aberrations in the imaging process. However, the opposite impacts on Bossung tilt from each pole results in an overall improvement for dipole illumination. Reduced Bossung tilt and a 21% improvement of the overlapping process window are achieved by the insertion of asymmetric SRAFs into the 2-bar mask design.

  11. Listening talkers produce great spectral tilt contrasts

    DEFF Research Database (Denmark)

    Christiansen, Thomas Ulrich; Heegård, Jan; Henrichsen, Peter Juel

    of colored geometrical shapes taken from DanPASS [2]. The spectral tilt was gauged by calculating the band-level difference in dB between two frequency bands with pass-bands 150 to 803 Hz and 803 to 1358 Hz respectively in 5 ms intervals. This was done separately for intervals containing content words...

  12. "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…

  13. Temperament and character personality dimensions in nitrate-tilt-induced vasovagal syncope patients.

    Science.gov (United States)

    Russo, Vincenzo; AlTurki, Ahmed; Rago, Anna; Proietti, Riccardo; Chaussé, Guillaume; Monteleone, Alessio Maria; Scognamiglio, Pasquale; Monteleone, Palmiero; Nigro, Gerardo

    2017-02-16

    Vasovagal syncope (VVS) is a clinical syndrome that is characterized by a transient loss of consciousness and postural tone that are due to a temporary, spontaneously self-terminating global cerebral hypoperfusion. It is known that personality modulates the individual's sensitivity to stressors and that emotional arousal and psychologic uncertainty are conditions that contribute to vasodepressor syncope. Therefore, it is postulated that the personality characteristics of VVS patients could play a role in the pathophysiology of VVS. The aim of our study was to evaluate the temperament and character personality dimensions in patients with VVS as confirmed by nitrate-induced tilt testing. From the 450 consecutive patients referred to our Syncope Unit for transient loss of consciousness, we enrolled 162 patients who had positive results from the head up tilt test for VVS and 162 healthy subjects matched for age and sex. All patients underwent a structured clinical interview with a psychologist to exclude the presence of current psychiatric comorbidities and were asked to complete the Cloninger's Temperament and Character Inventory-Revised (TCI-R) questionnaire for psychological assessment. Compared to healthy subjects, both male and female patients with VVS were found to have higher scores of the persistence temperament and self-transcendence character traits. Moreover, male VVS patients had lower scores in "novelty seeking", while female VVS patients scored significantly higher in "reward dependence". Our data show that VVS patients significantly differ from matched healthy controls in some temperament and character personality dimensions. Cardiologists should consider referral for psychological assessment when treating patients with refractory VVS. Copyright © 2017 Hellenic Cardiological Society. Published by Elsevier B.V. All rights reserved.

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

    Indian Academy of Sciences (India)

    2014-02-06

    Feb 6, 2014 ... This paper reports the study on development of tilted fibre Bragg gratings using highly coherent 255 nm radiation, obtained from the second harmonic generation (SHG) of copper vapour laser (CVL). The transmission and reflection spectra of the tilted fibre Bragg gratings (TFBG) were studied for the tilt ...

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

    Science.gov (United States)

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

    1990-01-01

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

  16. 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.

  17. Inverse solutions for tilting orthogonal double prisms.

    Science.gov (United States)

    Li, Anhu; Ding, Ye; Bian, Yongming; Liu, Liren

    2014-06-10

    An analytical reverse solution and actual examples are given to show how to direct a laser beam from a pair of orthogonal prisms to given targets in free space. Considering the influences of double-prism structural parameters, a lookup table method to seek the numerical reverse solution of each prism's tilting angle is also proposed for steering the double-prism orientation to track a target position located in the near field. Some case studies, as well as a specified elliptical target trajectory scanned by the cam-based driving double prisms, exhibit the significant application values of the theoretical derivation. The analytic reverse and numerical solutions can be generalized to investigate the synthesis of scanning patterns and the controlling strategy of double-prism tilting motion, the potentials of which can be explored to perform the orientation and position tracking functions in applications of precision engineering fields.

  18. Tilting Shear Layers in Coastal Flows

    Science.gov (United States)

    2015-09-30

    term goals of this research are to explore the evolution of flows with strong horizontal shear and horizontal density gradients (see Figure 1). These...converting horizontal shear to vertical shear. The horizontal shear leads to the growth of vertical vortices that are subsequently tilted, stretched...small-scale flows influence the water properties within the lagoons and merge with the larger scale flows around the islands. Specific targets are: 1

  19. GAS MOVEMENT IN ROTARY TILTING FURNACES

    Directory of Open Access Journals (Sweden)

    S. L. Rovin

    2016-01-01

    Full Text Available The article presents the results of studies of gas movement and heat and mass transfer processes in the rotary tilting furnace (RTF at the heat treatment of disperse materials. The study was performed through computer modeling using software packages ANSYS CFX and Solid Works Flow Simulation. The results were used to design RTF with different capacity and application and helped to improve their technical and economic characteristics.

  20. 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.

  1. 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.

  2. Comparison of Indiana High School Football Injury Rates by Inclusion of the USA Football “Heads Up Football” Player Safety Coach

    Science.gov (United States)

    Kerr, Zachary Y.; Dalton, Sara L.; Roos, Karen G.; Djoko, Aristarque; Phelps, Jennifer; Dompier, Thomas P.

    2016-01-01

    Background: In Indiana, high school football coaches are required to complete a coaching education course with material related to concussion awareness, equipment fitting, heat emergency preparedness, and proper technique. Some high schools have also opted to implement a player safety coach (PSC). The PSC, an integral component of USA Football’s Heads Up Football (HUF) program, is a coach whose primary responsibility is to ensure that other coaches are implementing proper tackling and blocking techniques alongside other components of the HUF program. Purpose: To compare injury rates in Indiana high school football teams by their usage of a PSC or online coaching education only. Study Design: Cohort study; Level of evidence, 2. Methods: Athletic trainers (ATs) evaluated and tracked injuries at each practice and game during the 2015 high school football season. Players were drawn from 6 teams in Indiana. The PSC group, which used the PSC component, was comprised of 204 players from 3 teams. The “education only” group (EDU), which utilized coaching education only, was composed of 186 players from 3 teams. Injury rates and injury rate ratios (IRRs) were reported with 95% confidence intervals (CIs). Results: During 25,938 athlete-exposures (AEs), a total of 149 injuries were reported, of which 54 (36.2%) and 95 (63.8%) originated from the PSC and EDU groups, respectively. The practice injury rate was lower in the PSC group than the EDU group (2.99 vs 4.83/1000 AEs; IRR, 0.62; 95% CI, 0.40-0.95). The game injury rate was also lower in the PSC group than the EDU group (11.37 vs 26.37/1000 AEs; IRR, 0.43; 95% CI, 0.25-0.74). When restricted to concussions only, the rate was lower in the PSC group (0.09 vs 0.73/1000 AEs; IRR, 0.12; 95% CI, 0.01-0.94), although only 1 concussion was reported in the PSC group. No differences were found in game concussion rates (0.60 vs 4.39/1000 AEs; IRR, 0.14; 95% CI, 0.02-1.11). Conclusion: Findings support the PSC as an effective

  3. Speed benefits of tilt-rotor designs for LHX

    Science.gov (United States)

    Mcdaniel, R. L.; Adams, J. V.; Balberde, A.; Dereska, S. P.; Gearin, C. J.; Shaw, D. E.

    1983-01-01

    The merits of an advanced helicopter and a tilt rotor aircraft for light utility, scout, and attack roles in combat missions envisioned for the year 2000 and beyond were compared. It is demonstrated that speed has increasing value for 11 different mission classes broadly encompassing the intended LHX roles. Helicopter speeds beyond 250 knots are judged to have lower military worth. Since the tilt rotor concept offers a different cost speed relationship than that of helicopters, assessment of a tilt rotor LHX variant was warranted. The technical parameters of an advanced tilt rotor are stablished. Parameters of representative missions are identified, computed relative value of the tilt rotor LHX are compared to the baseline helicopter, a first-order life cycle estimate for the tilt rotor LHX is established, military worth of the alternative design is computed and the results are evaluated. It is suggested that the tilt rotor is the solution with the greatest capability for meeting the uncertainties of future needs.

  4. Tilted foils polarization at REX-ISOLDE

    CERN Document Server

    Tornqvist, H; Yordanov, D T; Imai, N; Heinz, A; Nilsson, T; Sotty, C; Hass, M; Georgiev, G; Johansson, H; Dhal, A; Stuchbery, A; Wenander, F; Hirayama, Y; Kusoglu, A; Balabanski, D

    2013-01-01

    The tilted-foils nuclear-spin polarization method has been evaluated using the REX-ISOLDE linear accelerator at the ISOLDE facility, CERN. A beam of Li-8 delivered with an energy of 300 keV/u traversed through one Mylar foil to degrade the beam energy to 200 keV/u and consequently through 10 thin diamond-like carbon foils to polarize the nuclear spin. The attained nuclear spin polarization of 3.6 +/- 0.3% was measured with a beta-NMR setup. (C) 2013 Elsevier B.V. All rights reserved.

  5. Analysis of fast switching in tilted media

    Energy Technology Data Exchange (ETDEWEB)

    D' Aquino, M. [Department of Electrical Engineering, University of Napoli ' Federico II' , via Claudio 21, I-80125 (Italy)]. E-mail: mdaquino@unina.it; Suess, D. [Department of Solid State Physics, Vienna University of Technology, Vienna (Austria); Schrefl, T. [Department of Solid State Physics, Vienna University of Technology, Vienna (Austria); Serpico, C. [Department of Electrical Engineering, University of Napoli ' Federico II' , via Claudio 21, I-80125 (Italy); Fidler, J. [Department of Solid State Physics, Vienna University of Technology, Vienna (Austria)

    2005-04-15

    A uniform mode theory is used to find the parameter range for realizing fast switching below the Stoner-Wohlfarth limit in weakly coupled granular tilted media. The theory is used to estimate the field amplitudes and directions for simultaneous switching of a family of uniformly magnetized and noninteracting grains with dispersion in the easy axis and initial magnetization directions. The effect of interactions is then studied numerically by using a 3D finite element micromagnetic simulations. The numerical results shows that the theory provides rather accurate estimate. In addition, it is verified that in an appropriate range of applied field amplitudes the switching time decreases by decreasing the external field.

  6. Trigonometry-Integrated 'Lift' Technique (TILT) for Restoring Volar Tilt in Distal Radius Fractures: Description of Technique and Preliminary Results.

    Science.gov (United States)

    Sechachalam, Sreedharan; Satku, Mala; Wong, Jian Hao Kevin; Tan, Lester Teong Jin; Yong, Fok Chuan

    2017-03-01

    Restoration of extra-articular and intra-articular parameters are important considerations during operative fixation of distal radius fractures. Restoration of volar tilt by using visual estimation and the 'lift' technique has previously been described. The aim of our study was to describe a mathematical technique for accurately restoring the volar tilt of the distal radius to acceptable anatomic values. A retrospective review of cases performed using the trigonometry-integrated ' lift' technique (TILT) was performed. This technique uses the pre-operative volar tilt angle as well as the dimensions of the implant to calculate the 'lift' required to restore volar tilt. Intra-operative angles were measured using a marked transparency overlay on fluoroscopic images. Pre-operative and post-operative volar tilt were measured and analysed. Twenty-seven fractures were included in the study, with 20 being classified as Arbeitsgemeinschaft für Osteosynthesefragen (AO) C-type. Pre-'lift' volar tilt ranged from 0° to -20°. Post-'lift' volar tilt ranged from 2° to 16°, with all but three cases ranging from 5° to 15°. The mean volar tilt achieved was 10.2°. The trigonometry-integrated 'lift' technique resulted in reliable intra-operative restoration of anatomic volar tilt in distal radius fractures.

  7. 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.

  8. INVESTIGATIONS ON OPERATION OF ROTARY TILTING FURNACES

    Directory of Open Access Journals (Sweden)

    S. L. Rovin

    2016-01-01

    Full Text Available Rotary tilting furnace (RTF is a new type of fuel furnaces, that provide the most efficient heating and recycling of polydisperse materials. The paper describes results of the investigations on thermal processes in the RTF, movement of materials and non-isothermal gas flow during kiln rotary process. The investigations have been carried out while using physical and computer simulations and under actual operating conditions applying the pilot plant. Results of the research have served as a basis for development of recommendations on the RTF calculations and designing and they have been also used for constructional design of a rotary tilting furnace for heating and melting of cast iron chips, reduction smelting of steel mill scale, melting of aluminum scrap, melting of lead from battery scrap. These furnaces have a high thermal efficiency (~50 %, technological flexibility, high productivity and profitability. Proven technical solutions for recycling of ferrous and non-ferrous metals develop the use of RTF in the foundry and metallurgical industry as the main technological unit for creation of cost-effective small-tonnage recycling of metal waste generated at the plants. The research results open prospects for organization of its own production for high-quality charging material in Belarus in lieu of imported primary metal. The proposed technology makes it possible to solve environmental challenge pertaining to liquidation of multi-tonnage heaps of metal-containing wastes.

  9. Measuring Earth’s axial tilt with a telescope

    Science.gov (United States)

    Suat Isildak, R.; Asuman Küçüközer, H.; Isik, Hakan

    2017-05-01

    In this study, a method to measure the Earth’s axial tilt is attempted by using a telescope. As a principal instrument, telescopes in astronomy courses are mostly to verify the astronomical objects in sky and not to make sense of astronomical events such as seasonal changes which is explained by the Earth’s axial tilt. This study outlines telescopic measurements to calculate the axial tilt at winter solstice.

  10. 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 ...

  11. 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.

  12. 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

  13. Predicting tilt of a double pendulum

    Science.gov (United States)

    Strom, George J.

    1986-05-01

    An iterative computer method is described that has been used to calculate the proper settings of the lengths of six turnbuckles used in the hoisting of the 24,000-lb Hubble Space Telescope and components during assembly. The various sections are required to hang very close to level (within a few arc-seconds) when hoisted. The hoisting gear is a delta (triangular) frame suspended by three chains from a single hook on the hoist. Three long cables attached to the bottom of the frame are attached to the Space Telescope. The chains and frame and the cables and telescope together constitute a double pendulum. After correcting some errors in the CG calculations and fixing a large discrepancy in the supposed coordinates of the attach points, a nearly perfect result (6 arcmin tilt in one plane, 3 arcmin in the other) was obtained. The program gives a satisfactory answer in 30 seconds; at most, one adjustment of the turnbuckles is required.

  14. Tilt anisoplanatism in extended turbulence propagation

    Science.gov (United States)

    Magee, Eric P.; Whiteley, Matthew R.; Das, Shashikala T.; Welsh, Byron M.

    2003-04-01

    The use of high-energy laser (HEL) weapon systems in tactical air-to-ground target engagements offers great promise for revolutionizing the USAF's war-fighting capabilities. Laser directed-energy systems will enable ultra-precision strike with minimal collateral damage and significant stand-off range for the aerial platform. The tactical directed energy application differs in many crucial ways from the conventional approach used in missile defense. Tactical missions occur at much lower altitudes and involve look-down to low-contrast ground targets instead of a high-contrast boosting missile. At these lower altitudes, the strength of atmospheric turbulence is greatly enhanced. Although the target slant ranges are much shorter, tactical missions may still involve moderate values of the Rytov number (0.1-0.5), and small isoplanatic angles compared to the diffraction angle. With increased density of air in the propagation path, and the potential for slow-moving or stationary ground targets, HEL-induced thermal blooming will certainly be a concern. In order to minimize the errors induced by tracking through thermal blooming, offset aimpoint tracking can be used. However, this will result in significant tilt anisoplanatism, thus degrading beam stabilization on target. In this paper we investigate the effects of extended turbulence on tracking (or tilt) anisoplanatism using theory and wave optics simulations. The simulations show good agreement with geometric optics predictions at angles larger than about 5 micro-radians (asymptotic regime) while at smaller angles the agreement is poor. We present a theoretical basis for this observation.

  15. Vesicle shape, molecular tilt, and the suppression of necks

    Science.gov (United States)

    Jiang, Hongyuan; Huber, Greg; Pelcovits, Robert A.; Powers, Thomas R.

    2007-09-01

    Can the presence of molecular-tilt order significantly affect the shapes of lipid bilayer membranes, particularly membrane shapes with narrow necks? Motivated by the propensity for tilt order and the common occurrence of narrow necks in the intermediate stages of biological processes such as endocytosis and vesicle trafficking, we examine how tilt order inhibits the formation of necks in the equilibrium shapes of vesicles. For vesicles with a spherical topology, point defects in the molecular order with a total strength of +2 are required. We study axisymmetric shapes and suppose that there is a unit-strength defect at each pole of the vesicle. The model is further simplified by the assumption of tilt isotropy: invariance of the energy with respect to rotations of the molecules about the local membrane normal. This isotropy condition leads to a minimal coupling of tilt order and curvature, giving a high energetic cost to regions with Gaussian curvature and tilt order. Minimizing the elastic free energy with constraints of fixed area and fixed enclosed volume determines the allowed shapes. Using numerical calculations, we find several branches of solutions and identify them with the branches previously known for fluid membranes. We find that tilt order changes the relative energy of the branches, suppressing thin necks by making them costly, leading to elongated prolate vesicles as a generic family of tilt-ordered membrane shapes.

  16. determination of determination of optimal tilt angle for maximum

    African Journals Online (AJOL)

    eobe

    The paper analyses the solar radiation data estimated from sunshine hours and ambient temperature to predict the PV energy output at the site. The analysis showed that the best tilt angle for PV energy production is 60 if the module is fixed module is fixed but if adjusted monthly, the best tilt angle for each month will be 300, ...

  17. Tilting of trucks: a driver education system and warning system

    NARCIS (Netherlands)

    Kleuskens, R.J.A.

    1996-01-01

    To reduce the risk of tilting, TNO has developed a tilt warning system for commercial vehicles. This system is able to monitor vehicle weight, lateral acceleration and velocity during normal operation. The system CPU is constantly comparing the measured lateral acceleration to a calculated limit

  18. 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)

  19. Tilt displacement range testing for a piezoelectric deformable mirror

    Science.gov (United States)

    Wang, Dongdong; Hao, Qun; Song, Yong; Cheng, Xuemin; Fan, Fan; Li, Heng

    2016-10-01

    In our previous works, we presented a zoom system and image stabilization design based on deformable mirrors (DMs). According to the high bandwidth and free edge characteristics of the piezoelectric deformable mirror (PDM), we tested the system's image-stable capability. We found the PDM could realize some tilt displacements while keeping a certain stable surface shape, it could obtain higher image stabilizing precision when integrated with the traditional mechanical image stabilization systems. In the design of the image stabilization system, the PDM's tilt displacement range is a key factor for consideration. So in this paper, we carried out a tilt displacement range testing experiment by using the OKO's 37-channel PDM. We measured and analyzed the variation of the tilt displacements in optical image stabilization process, and calculated the maximum tilt angle as the PDM surface shape was stabilized. We built an experimental platform consisting of a fixed target, an imaging system based on PDM, and a CCD camera. We used the ZYGO interferometer as an evaluation instrument to measure the surface shape stability. When the PDM surface had a tilt displacement, the image point of the fixed target on the camera sensor shifted correspondingly. The tilt angle of the PDM could be obtained by calculating this shift. The results showed that the maximum tilt angle of the PDM was 0.2mrad. The paper also analyzed the experiment errors when concerning about the off-axis error of the PDM deflection center.

  20. Clinical measurement of compensatory torsional eye movement during head tilt.

    Science.gov (United States)

    Lim, Han Woong; Kim, Ji Hong; Park, Seung Hun; Oh, Sei Yeul

    2017-03-01

    To measure the degree of compensatory torsional eye movement during head tilt using a fundus photography method. We enrolled 55 healthy subjects who were 20-66 years of age. Fundus photographs were obtained in the presumed baseline position and in stepwise head tilt positions to evaluate ocular torsion using a non-mydriatic fundus camera. Horizontal marks on the nose were photographed simultaneously to evaluate head tilt. Images were analysed using Photoshop to measure the degree of ocular torsion and head tilt. A consistent compensatory torsional eye movement was observed in all subjects during head tilt. The degree of compensatory torsional eye movement showed a positive correlation with the angle of head tilt. Ocular torsional disconjugacy was observed during head tilt, with larger excycloductional eye movement than incycloductional eye movement (4.88 ± 2.91° versus 4.50 ± 2.76°, p eye movement was significantly associated with the degree of head tilt (β = 0.191, p eye movement. Considering the availability of fundus photography in clinical ophthalmology practice, the proposed method can be used as a clinical tool to measure compensatory torsional eye movement. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  1. Orthostatic symptoms does not always manifest during tilt-table test in pediatric postural orthostatic tachycardia syndrome patients

    Directory of Open Access Journals (Sweden)

    Tae-Eon Huh

    2013-01-01

    Full Text Available &lt;b&gt;Purpose:&lt;/b&gt; Chronic day-to-day symptoms of orthostatic intolerance are the most notable features of postural orthostatic tachycardia syndrome (POTS. However, we have encountered patients with such symptoms and excessive tachycardia but with no symptoms during the tilt-table test (TTT. We aimed to investigate whether POTS patients with chronic orthostatic intolerance always present orthostatic symptoms during the TTT and analyze the factors underlying symptom manifestation during this test. &lt;b&gt;Methods:&lt;/b&gt; We retrospectively examined patients who presented with POTS at the Gyeongsang Na tional University Hospital between 2008 and 2011. Diagnosis of POTS was based on chronic day-to-day orthostatic intolerance symptoms as well as excessive tachycardia during the TTT. The patients were divided two groups depending on the presentation of orthostatic symptoms during the TTT. Clinical data and the results of the TTT were compared between these groups. &lt;b&gt;Results:&lt;/b&gt; In 22 patients, 7 patients (31.8% did not present orthostatic symptoms during the test. Diastolic blood pressure (BP was significantly lower in the symptom-positive group. The head-up tilt resulted in a significant increase in diastolic BP in the symptom-negative group (&lt;i&gt;P&lt;/i&gt; =0.04, while systolic BP had a tendency to decrease in the symptom-positive group (&lt;i&gt;P&lt;/i&gt; =0.06. &lt;b&gt;Conclusion:&lt;/b&gt; Significant patients with POTS did not present orthostatic symptoms during the TTT despite having chronic daily symptoms. This finding may be important for establishing definitive diagnostic criteria for pediatric POTS. Development of symptoms during TTT might be related to low diastolic BP and abnormal compensatory responses to orthostasis.

  2. Use of Highways in the Sky and a Virtual Pad for Landing Head Up Display Symbology to enable improved Helicopter Pilots Situation Awareness and Workload in Degraded Visual Conditions.

    Science.gov (United States)

    Stanton, Neville A; Plant, Katherine L; Roberts, Aaron P; Allison, Craig K

    2017-12-05

    Flight within degraded visual conditions is a great challenge to pilots of rotary-wing craft. Environmental cues typically used to guide interpretation of speed, location and approach can become obscured, forcing the pilots to rely on data available from in-cockpit instrumentation. To ease the task of flight during degraded visual conditions, pilots require easy access to flight critical information. The current study examined the effect of "Highways in the Sky" symbology and a conformal virtual pad for landing presented using a Head Up Display (HUD) on pilots' workload and situation awareness for both clear and degraded conditions across a series of simulated rotary-wing approach and landings. Results suggest that access to the HUD lead to significant improvements to pilots' situation awareness, especially within degraded visual conditions. Importantly access to the HUD facilitated pilot awareness in all conditions. Results are discussed in terms of future HUD development. Practitioner Summary This paper explores the use of a novel Heads Up Display, to facilitate rotary-wing pilots' situation awareness and workload for simulated flights in both clear and degraded visual conditions. Results suggest that access to HUD facilitated pilots' situation awareness, especially when flying in degraded conditions.

  3. Tilt-Sensitivity Analysis for Space Telescopes

    Science.gov (United States)

    Papalexandris, Miltiadis; Waluschka, Eugene

    2003-01-01

    A report discusses a computational-simulation study of phase-front propagation in the Laser Interferometer Space Antenna (LISA), in which space telescopes would transmit and receive metrological laser beams along 5-Gm interferometer arms. The main objective of the study was to determine the sensitivity of the average phase of a beam with respect to fluctuations in pointing of the beam. The simulations account for the effects of obscurations by a secondary mirror and its supporting struts in a telescope, and for the effects of optical imperfections (especially tilt) of a telescope. A significant innovation introduced in this study is a methodology, applicable to space telescopes in general, for predicting the effects of optical imperfections. This methodology involves a Monte Carlo simulation in which one generates many random wavefront distortions and studies their effects through computational simulations of propagation. Then one performs a statistical analysis of the results of the simulations and computes the functional relations among such important design parameters as the sizes of distortions and the mean value and the variance of the loss of performance. These functional relations provide information regarding position and orientation tolerances relevant to design and operation.

  4. Pulse Front Tilt and Laser Plasma Acceleration

    Science.gov (United States)

    Mittelberger, Daniel; Thévenet, Maxence; Nakamura, Kei; Lehe, Remi; Gonsalves, Anthony; Benedetti, Carlo; Leemans, Wim

    2017-10-01

    Pulse front tilt (PFT) is potentially present in any CPA laser system, but its effects may be overlooked because spatiotemporal pulse characterization is considerably more involved than measuring only spatial or temporal profile. PFT is particularly important for laser plasma accelerators (LPA) because it influences electron beam injection and steering. In this work, experimental results from the BELLA Center will be presented that demonstrate the effect of optical grating misalignment and optical compression, resulting in PFT, on accelerator performance. Theoretical models of laser and electron beam steering will be introduced based on particle-in-cell simulations showing distortion of the plasma wake. Theoretical predictions will be compared with experiments and complimentary simulations, and tolerances on PFT and optical compressor alignment will be developed as a function of LPA performance requirements. This work was supported by the Office of High Energy Physics, Office of Science, US Department of Energy under Contract DE-AC02-05CH11231 and the National Science Foundation under Grant PHY-1415596.

  5. Tip tilt corection for astronomical telescopes using adaptive control

    Energy Technology Data Exchange (ETDEWEB)

    Watson, J.

    1997-04-17

    The greatest hindrance to modern astronomy is the effect of the Earth`s atmosphere on incoming light. The fundamental, or lowest mode of disturbance is tip and tilt.. This mode causes the focused image of a distant point source to move about in a plane (X-Y motion) as viewed form a telescope objective. Tip-tilt correction systems can be used to correct for these disturbances in real time. We propose a novel application of adaptive control to address some unique problems inherent with tip-tilt correction systems for astronomical telescopes.

  6. Sweat patterns differ between tilt-induced reflex syncope and tilt-induced anxiety among youth.

    Science.gov (United States)

    Heyer, Geoffrey L; Harvey, Rebecca A; Islam, Monica P

    2016-08-01

    Profound sweating can occur with reflex-syncope and with emotional distress, but little is known about the similarities and differences between these sweat responses when they occur during orthostatic challenge. We sought to characterize and compare the sweat patterns related to tilt-induced syncope, presyncope, anxiety, and normal tilt testing. In a prospective observational study, quantitative sweat rate was measured from the abdomen, forearm, ankle, and thigh during head-upright tilt. Sweat characteristics were compared across tilt diagnoses of syncope, presyncope, anxiety, and normal testing. When anxiety and syncope/presyncope occurred during the same study (separated by ≥6 min), both were diagnosed. Our cohort comprised150 patients (15.1 ± 2.3 years; 82.9 % female) with 156 diagnoses: 76 with reflex-syncope, 31 with presyncope, 23 with anxiety, and 26 with normal results. All syncope/presyncope patients and 20 (87 %) of the anxiety patients had corresponding sweat responses. Minimal or negligible sweating occurred among patients with normal tests. Neither basal sweat (19.4 ± 4.7 versus 18.3 ± 3.7 versus 18.5 ± 3.7 nL/min/cm(2)) nor peak sweat (171 ± 47.4 versus 149.4 ± 64.4 versus 154.4 ± 59.2 nL/min/cm(2)) differed between patients with syncope, presyncope, or anxiety, p = .32 and p = .12, respectively. However, the qualitative sweat patterns related to syncope/presyncope (diffuse, smoothly contoured, symmetrical, single peaks) differed considerably from the sweat patterns related to anxiety (heterogeneous, asymmetrical, roughly contoured single-peak, multi-peak, or progressive sweat changes). The sweat patterns related to syncope/presyncope are distinguishable from the sweat patterns related to anxiety. Recognition of the different sweat patterns can inform how signs and symptoms are interpreted during clinical orthostatic challenge.

  7. 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.

  8. Formation of current density profile in tilted current sheets

    Directory of Open Access Journals (Sweden)

    A. A. Petrukovich

    2008-11-01

    Full Text Available We investigate Cluster observations of strongly tilted sheets (flapping events in the magnetotail. In accordance with the simple model of slip deformation (vertical differential displacement of neighboring flux tubes, the Jy current density component in the tilted sheet remains constant and equal to that in the horizontal undisturbed sheet. However, a substantial Jz component appears proportional to the local sheet tilt. Slip-type variations, having smaller scale than the full crossing, locally change the tilt and Jz and may thus create a variety of non-classical (bifurcated, asymmetric etc current density profiles.

  9. Self-stress vs manual stress in talar tilt radiography.

    Science.gov (United States)

    Lentell, Gary; Desch, Robert J; Tracz, Susan M; Nyberg, Lisa M

    2010-01-01

    Radiographic study following inversion ankle sprain commonly is used to determine the presence of anatomic laxity across the talocrural joint. To compare the degree of talar tilt derived from a radiographic ankle stress exam under 2 conditions: self-stress vs manual stress applied by the clinician. Twenty-four subjects seeking medical care following ankle sprain underwent talar tilt stress exams of both ankles. The involved ankle was imaged with self-stress by use of a strap and with the clinician providing manual stress during the imaging exam. Mean talar tilt for the self-stress method was 2.2 degrees, compared with 5.9 degrees for the manual stress method (P stress was provided by the clinician. To avoid false negative findings of anatomic laxity in stress talar tilt studies at the ankle, a standardized procedure in which the clinician provides manual stress may be necessary.

  10. 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.

  11. Analysis, design, and construction of tilt-up wall panel

    OpenAIRE

    Lim, Chim Chai

    1987-01-01

    The idea of tilt-up construction started in America in the early 1900's. In the beginning, this technique was mainly used on structures such as industrial warehouses and factories. However, recent developments and improvements in tilt-up construction technique and accessories have enabled this building method to be applied to many architecturally appealing offices and residential structures. There are many details the design-build team must consider to ensure the success of...

  12. Head-Up; An interdisciplinary, participatory and co-design process informing the development of a novel head and neck support for people living with progressive neck muscle weakness.

    Science.gov (United States)

    Reed, Heath; Langley, Joe; Stanton, Andy; Heron, Nicola; Clarke, Zoe; Judge, Simon; McCarthy, Avril; Squire, Gill; Quinn, Ann; Wells, Oliver; Tindale, Wendy; Baxter, Susan; Shaw, Pamela J; McDermott, Christopher J

    2014-01-01

    This paper presents the Head-Up project, that aims to provide innovative head support to help improve posture, relieve pain and aid communication for people living with progressive neck muscle weakness. The initial focus is motor neurone disease. The case study illustrates collaborative, interdisciplinary research and new product development underpinned by participatory design. The study was initiated by a 2-day stakeholder workshop followed by early proof-of-concept modelling and patient need evidence building. The work subsequently led to a successful NIHR i4i application funding a 24-month iterative design process, patenting, CE marking and clinical evaluation. The evaluation has informed amendments to the proposed design refered to here as the Sheffield Support Snood (SSS). The outcome positively demonstrates use and performance improvements over current neck orthoses and the process of multidisciplinary and user engagement has created a sense of ownership by MND participants, who have since acted as advocates for the product.

  13. 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

  14. 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

  15. Human perceptual overestimation of whole body roll tilt in hypergravity.

    Science.gov (United States)

    Clark, Torin K; Newman, Michael C; Oman, Charles M; Merfeld, Daniel M; Young, Laurence R

    2015-04-01

    Hypergravity provides a unique environment to study human perception of orientation. We utilized a long-radius centrifuge to study perception of both static and dynamic whole body roll tilt in hypergravity, across a range of angles, frequencies, and net gravito-inertial levels (referred to as G levels). While studies of static tilt perception in hypergravity have been published, this is the first to measure dynamic tilt perception (i.e., with time-varying canal stimulation) in hypergravity using a continuous matching task. In complete darkness, subjects reported their orientation perception using a haptic task, whereby they attempted to align a hand-held bar with their perceived horizontal. Static roll tilt was overestimated in hypergravity, with more overestimation at larger angles and higher G levels, across the conditions tested (overestimated by ∼35% per additional G level, P < 0.001). As our primary contribution, we show that dynamic roll tilt was also consistently overestimated in hypergravity (P < 0.001) at all angles and frequencies tested, again with more overestimation at higher G levels. The overestimation was similar to that for static tilts at low angular velocities but decreased at higher angular velocities (P = 0.006), consistent with semicircular canal sensory integration. To match our findings, we propose a modification to a previous Observer-type canal-otolith interaction model. Specifically, our data were better modeled by including the hypothesis that the central nervous system treats otolith stimulation in the utricular plane differently than stimulation out of the utricular plane. This modified model was able to simulate quantitatively both the static and the dynamic roll tilt overestimation in hypergravity measured experimentally. Copyright © 2015 the American Physiological Society.

  16. 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

  17. Use of Minute-by-Minute Cardiovascular Measurements During Tilt Tests to Strengthen Inference on the Effect of Long-Duration Space Flight on Orthostatic Hypotension

    Science.gov (United States)

    Feiveson, Alan H.; Lee, Stuart M. C.; Stenger, Michael B.; Stein, Sydney P.; Platts, Steven H.

    2011-01-01

    Typical methodology for evaluating the effects of spaceflight on orthostatic hypotension (OH) has been survival analysis of tolerance times from 80 head-up tilt tests. However when scheduled test durations are short, there may not be enough failures to allow survival analysis to adequately estimate and compare the effects of flight phase (e.g. pre-flight, number of days post-flight), flight duration, and their interaction, as well as interactions with effects of interventions or countermeasures. The problem is exacerbated in the presence of a repeated measures design, in which subjects participate in tilt tests during various flight phases. Here we show how it is possible to dramatically improve the efficiency of statistical inference in this setting by making use of the additional information contained in minute-by-minute observations of cardiovascular parameters thought to be reflective of progression towards presyncope during tilt testing. Methods: We retrospectively examined operational tilt test (OTT; 10 -min 80 head-up tilt) data from 20 International Space Station (ISS) and 66 Shuttle astronauts 10 d before launch (L-10), on landing day (R+0) and during recovery (R+1, R+3, R+6-10) depending on the level of participation. Data from 5 ISS astronauts tested on R+0 or R+1 who used non-standard countermeasures were excluded. In addition to OTT survival time, 8 cardiovascular parameters (CP: heart rate, systolic, diastolic, and mean arterial blood pressure, pulse pressure, stroke volume, cardiac output, and total peripheral resistance) that might be predictive of progression towards presyncope were measured every minute of each OTT. Statistical analysis was predicated on a two ]stage model of causation. In the first stage, flight duration and time from landing affect the astronauts' degree of OH, which is manifested in the time trends and variation of the above CPs during OTTs. In the second stage, the behavior of these parameters directly affects OTT survival

  18. 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, 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.

  19. Direct Writing with Tilted-Front Femtosecond Pulses.

    Science.gov (United States)

    Patel, Aabid; Svirko, Yuri; Durfee, Charles; Kazansky, Peter G

    2017-10-10

    Shaping light fields in both space and time provides new degrees of freedom to manipulate light-matter interaction on the ultrafast timescale. Through this exploitation of the light field, a greater appreciation of spatio-temporal couplings in focusing has been gained, shedding light on previously unexplored parameters of the femtosecond light pulse, including pulse front tilt and wavefront rotation. Here, we directly investigate the effect of major spatio-temporal couplings on light-matter interaction and reveal unambiguously that in transparent media, pulse front tilt gives rise to the directional asymmetry of the ultrafast laser writing. We demonstrate that the laser pulse with a tilted intensity front deposits energy more efficiently when writing along the tilt than when writing against, producing either an isotropic damage-like or a birefringent nanograting structure. The directional asymmetry in the ultrafast laser writing is qualitatively described in terms of the interaction of a void trapped within the focal volume by the gradient force from the tilted intensity front and the thermocapillary force caused by the gradient of temperature. The observed instantaneous transition from the damage-like to nanograting modification after a finite writing length in a transparent dielectric is phenomenologically described in terms of the first-order phase transition.

  20. Heads Up: Concussion in Youth Sports

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  2. Projection/Reflection Heads-up Display

    Data.gov (United States)

    National Aeronautics and Space Administration — To address the NASA need for an extravehicular activity (EVA) information display device, Physical Optics Corporation (POC) proposes to advance development of a new...

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  5. 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.

  6. 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.

    2017-08-01

    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.

  7. A compound multilayer Laue lens with multiple tilting angles

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Liang; Yue, Shuaipeng; Li, Ming; Liu, Peng; Chang, Guangcai, E-mail: changgc@ihep.ac.cn

    2016-01-11

    The multilayer Laue lens (MLL) is a diffractive focusing optic with large aspect ratio, where dynamical diffraction effects dominate the focusing performance. Owing to the dynamical diffraction effects, the tilted MLL cannot effectively focus hard X-ray to below 10 nm; in contrast, the wedged MLL can theoretically focus hard X-ray to below 1 nm with very high efficiency, but it is more difficult to fabricate than tilted MLL. Here, a new structure of MLL and its design method are proposed, namely compound MLL with multiple tilting angles, which can focus the hard X-ray to below 10 nm with high efficiency and be easier to fabricate than wedged MLL.

  8. Coulomb interaction effect in tilted Weyl fermion in two dimensions

    Science.gov (United States)

    Isobe, Hiroki; Nagaosa, Naoto

    Weyl fermions with tilted linear dispersions characterized by several different velocities appear in some systems including the quasi-two-dimensional organic semiconductor α-(BEDT-TTF)2I3 and three-dimensional WTe2. The Coulomb interaction between electrons modifies the velocities in an essential way in the low energy limit, where the logarithmic corrections dominate. Taking into account the coupling to both the transverse and longitudinal electromagnetic fields, we derive the renormalization group equations for the velocities of the tilted Weyl fermions in two dimensions, and found that they increase as the energy decreases and eventually hit the velocity of light c to result in the Cherenkov radiation. Especially, the system restores the isotropic Weyl cone even when the bare Weyl cone is strongly tilted and the velocity of electrons becomes negative in certain directions.

  9. The semiology of tilt-induced psychogenic pseudosyncope.

    Science.gov (United States)

    Tannemaat, Martijn R; van Niekerk, Julius; Reijntjes, Robert H; Thijs, Roland D; Sutton, Richard; van Dijk, J Gert

    2013-08-20

    To provide a detailed semiology to aid the clinical recognition of psychogenic pseudosyncope (PPS), which concerns episodes of apparent transient loss of consciousness (TLOC) that mimic syncope. We analyzed all consecutive tilt-table tests from 2006 to 2012 showing proven PPS, i.e., apparent TLOC had occurred without EEG changes or a decrease in heart rate (HR) or blood pressure (BP). We analyzed baseline characteristics, video data, EEG, ECG, and continuous BP measurements on a 1-second time scale. Data were compared with those of 69 cases of tilt-induced vasovagal syncope (VVS). Of 800 tilt-table tests, 43 (5.4%) resulted in PPS. The majority (74%) were women. The median duration of apparent TLOC was longer in PPS (44 seconds) than in VVS (20 seconds, p semiology of PPS as a clinical entity is vital to ensure accurate diagnosis.

  10. Programming Tilting Angles in Shape Memory Polymer Janus Pillar Arrays with Unidirectional Wetting against the Tilting Direction.

    Science.gov (United States)

    Chen, Chi-Mon; Chiang, Chang-Lung; Yang, Shu

    2015-09-08

    By coating a thin layer of metal, including gold and gold-palladium alloy, of different thickness on the deformed shape memory polymer (SMP) pillars, we manipulate the degree of recovery of the SMP pillars. Pillars of different tilting angles were obtained as a result of balancing the strain recovery energy of the SMP pillars that favor the original straight state and the elastic energy of the metal layers that prefer the bent state. With this selective coating of a metal layer on the tilted pillars, we report a unique anisotropic liquid spreading behavior, where the water droplet is fully pinned in the direction of pillar tilting but advances in the reverse direction. This phenomenon is explained by the interplay of the surface chemistry and topography.

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

    DEFF Research Database (Denmark)

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

    2010-01-01

    An analysis of flow tilt angles from a fetch-limited beech forest site with clearings is presented in the context of vertical advection of carbon dioxide. Flow angles and vertical velocities from two sonic anemometers by different manufacturers were analyzed. Instead of using rotations, where zero...... balance, unless all terms in the carbon dioxide conservation equation can be precisely estimated....

  12. Theory of helical structures of tilted chiral lipid bilayers

    Science.gov (United States)

    Ou-Yang Zhong-Can; Liu Jixing

    1991-06-01

    Analogous to the theory of cholesteric liquid crystal, a theory for tilted chiral lipid bilayers (TCLB) [briefly reported in Phys. Rev. Lett. 65, 1679 (1990)] is developed. The tilt equation and the surface-shape-equilibrium equation have been derived. Application of the theory shows that on a cylindrical surface, the field of tilt directions of TCLB molecules forms a right-handed helix with a 45° gradient angle for k2>0 or a left-handed helix with -45° gradient angle for k2cholesteric liquid crystal. In addition, there exists another type of helical structure that looks like twisted strips or helicoids. It is also shown that on a spherical surface, the tilt field has at least two singular points. Based on these results, the succession of transitions from a vesicular dispersion to a phase involving helical structures and then to tubes observed in several laboratories can be reasonably explained. The general formula that explains the aggregation of narrow and prolate ribbon structures is derived. By including more terms of elasticity free energy into the theory, the size of the helical structure is obtained and is shown to agree with experimental observations.

  13. Rainbows with a tilted <111> Si very thin crystal

    Energy Technology Data Exchange (ETDEWEB)

    Neskovic, N.; Petrovic, S.; Borka, D.; Kossionides, S

    2002-11-11

    The angular distributions of protons channeled in a tilted <111> Si very thin crystal together with the corresponding rainbow patterns are considered. The proton energy is 10 MeV while the crystal thickness is 121.1 nm, corresponding to the reduced crystal thickness of 0.15. The tilt angle of the crystal is varied from zero up to the critical angle for channeling. The angular distributions were obtained using the numerical solution of the proton equations of motion and the computer simulation method. The rainbow lines were determined by applying the theory of crystal rainbows. The analysis has shown that the evolution of the angular distribution with the tilt angle can be fully explained by the evolution of the crystal rainbow. We have discovered that the crystal rainbow effect turns into the well-know doughnut effect in ion channeling for the larger values of the tilt angle. The interior of the doughnut is the analogue of the Alexander's dark band, which occurs in between the primary and secondary meteorological rainbows.

  14. 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...

  15. 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

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

    Indian Academy of Sciences (India)

    2014-02-06

    Feb 6, 2014 ... very efficient source for writing FBGs using phase mask as well as interferometers [4–7]. In this paper, we ... Figure 1 shows the experimental set-up for writing the tilted fibre Bragg grating. High spatial coherent UV .... [1] R Kashyap, Fibre Bragg grating (Academic Press, New York, 1999). [2] T Erdogan and ...

  17. Modelling of LEG tilting pad journal bearings with active lubrication

    DEFF Research Database (Denmark)

    Cerda Varela, Alejandro Javier; García, Asier Bengoechea; Santos, Ilmar

    2017-01-01

    This work constitutes the first step in a research effort aimed at studying the feasibility of introducing an active lubrication concept in tilting pad journal bearings (TPJBs) that feature the leading edge groove (LEG) lubrication system. The modification of the oil flow into each pad supply...... to portray the feasibility of affecting its static and dynamic properties by introducing this novel active bearing design....

  18. 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.

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

    Indian Academy of Sciences (India)

    Magnetic data processing methods such as diurnal correction, noise removal, reduction to pole, tilt derivative and downward continuation have been used to process the data and for the interpretation of results on the basis of magnetic properties of overlying materials which change with the temperature variation above or ...

  20. Cataract Surgery for Tilted Lens in Peters' Anomaly Type 2

    Directory of Open Access Journals (Sweden)

    Tadayuki Nishide

    2013-09-01

    Full Text Available Background: Cases of cataract surgery without penetrating keratoplasty in patients with Peters' anomaly are very rare. We report a case of Peters' anomaly type 2 with tilted lens due to synechia between the lens and iris that was treated with cataract surgery without penetrating keratoplasty. Case Presentation: A 16-year-old girl had Peters' anomaly in both eyes. Corneal opacity was severe in the left eye due to high-grade dysgenesis of the anterior segment. In the right eye, corneal opacity had spread from the center of the cornea to the inferotemporal side, and there was synechia between the iris and corneal endothelium from the inferonasal side to the inferotemporal side. Opacity was observed in the anterior pole of the lens, and there was synechia between the anterior iris and the lens. Ultrasound biomicroscopy (UBM revealed that the lens was tilted because of synechia. The tilted lens induced astigmatism, which reduced visual acuity to 20/250, in conjunction with a cataract. Cataract surgery was performed; the synechia between the lens capsule and the iris was severed, an intraocular lens was inserted, and the tilt was repaired. UBM was used postoperatively to confirm that the lens capsule synechia had been corrected and that the intraocular lens was not tilted. As a result, visual acuity improved to 20/100; glaucoma and expansion of corneal opacity were not observed. Conclusions: Severing of the synechia between the cataract and iris, during cataract surgery, in a patient with Peters' anomaly type 2 resulted in favorable postoperative visual acuity.

  1. 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.

  2. 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.

  3. 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

  4. A reinvestigation of the reference frame of the tilt-adaptation aftereffect

    NARCIS (Netherlands)

    Mathot, S.; Theeuwes, J.

    2013-01-01

    The tilt-adaptation aftereffect (TAE) is the phenomenon that prolonged perception of a tilted 'adapter' stimulus affects the perceived tilt of a subsequent 'tester' stimulus. Although it is clear that TAE is strongest when adapter and tester are presented at the same location, the reference frame of

  5. Triangle tilt and steel osteotomy: similar approaches to common problems.

    Science.gov (United States)

    Nath, Rahul K; Somasundaram, Chandra; Mahmooduddin, Faiz

    2011-03-24

    Each year, thousands of children worldwide suffer obstetric brachial plexus nerve injuries resulting not only in primary nerve injury, but also in development of secondary muscle and bone deformities of the shoulder. The triangle tilt surgery has been developed and shown to effectively address these deformities. The triangle tilt procedure was initially designed by the lead author (RKN) to follow the concepts of joint normalization featured in the Steel pelvic osteotomy used to correct developmental dysplasia of the hip joint, and indeed ultimately bears a striking resemblance to the Steel osteotomy. Prior to performing these bony surgical procedures, soft tissue procedures are performed to release the muscle contractures of the shoulder and hip. The purpose of this article is to compare and analyze the similarities between the indications, surgical techniques, involved anatomy, and outcomes of these operative procedures. A literature review was conducted using PubMed to identify articles pertaining to triangle tilt surgery and the Steel pelvic osteotomy. Functional parameters and surgical strategies were compared. Pre- and post-operative CTs were analyzed to compare anatomical results of the procedures. Similarities were found between both procedures in terms of indications, involved anatomy, surgical techniques, and outcomes. The triangle tilt surgery is indicated to correct the developmental dysplasia of the glenohumeral joint in obstetric brachial plexus injury patients. Steel pelvic osteotomy is performed to correct the subluxation and dislocation of the hip innominate bone in patients with congenital dysplasia, cerebral palsy myelodysplasia, and poliomyelitis. The involved anatomy of both procedures is similar in that both involve limb girdles and ball-and-socket joints, namely the shoulder and hip. Both procedures are also triple osteotomies, the triangle tilt involving the acromion, clavicle and scapula while the Steel osteotomy involves the iliac spine

  6. Decreasing cerebral oxygen consumption during upright tilt in vasovagal syncope.

    Science.gov (United States)

    Medow, Marvin S; Kothari, Mira L; Goetz, Amanda M; O'Donnell-Smith, Mary Breige; Terilli, Courtney; Stewart, Julian M

    2017-05-01

    We measured changes in transcranial Doppler ultrasound (TCD) and near infrared spectroscopy (NIRS) during 70° upright tilt in patients with recurrent vasovagal syncope (VVS, N = 20), postural tachycardia syndrome (POTS, N = 20), and healthy controls (N = 12) aged 15-27 years old. VVS was included if they fainted during testing within 5-15 min of upright tilt. We combined TCD and NIRS to obtain estimates of percent change in the cerebral metabolic rate of oxygen consumption (CMRO2), cerebral blood flow velocity (CBFv), and oxygen extraction fraction (OEF). Over the course of 10 min of upright tilt, CBFv decreased from a baseline of 70 ± 5 to 63 ± 5 cm/sec in controls and 74 ± 3 to 64 ± 3 cm/sec in POTS while decreasing from 74 ± 4 to 44 ± 3 cm/sec in VVS CMRO2 was unchanged in POTS and controls during tilt while OEF increased by 19 ± 3% and 15 ± 3%, respectively. CMRO2 decreased by 31 ± 3% in VVS during tilt while OEF only increased by 7 ± 3%. Oxyhemoglobin decreased by 1.1 ± 1.3 μmol/kg brain tissue in controls, by 1.1 ± 1.3 μmol/kg in POTS, and 11.1 ± 1.3 μmol/kg in VVS CBFv and CMRO2 fell steadily in VVS during upright tilt. The deficit in CMRO2 in VVS results from inadequate OEF in the face of greatly reduced CBF. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  7. 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...... 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 is the case with pockets designed for hydrostatic jacking. Such recesses are characterized by low...... 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...

  8. Tilted Foils Nuclear Spin Polarization at REX-ISOLDE

    CERN Document Server

    Törnqvist, Hans Toshihide

    2013-08-08

    This thesis will explain and summarize my work and involvement in experiments aimed at producing nuclear spin polarization of post-accelerated beams of ions with the tilted-foils technique at the REX-ISOLDE linear accelerator at CERN. Polarizing the nuclear spin of radioactive beams in particular may provide access to observables which may be difficult to obtain otherwise. Currently, the techniques commonly employed for nuclear spin polarization are restricted to specific nuclides and experimental measurement techniques. Tilted foils polarization may provide a new tool to extend the range of nuclides that can be polarized and the types of experiments that can be performed. The experiments rely not only on the production but also on the method to measure the degree of attained polarization. Two methods will be treated, based on particle scattering in Coulomb excitation that may be utilized for stable beams, and the $\\beta$-NMR that requires $\\beta$-decaying nuclei. The experimental setups and measurements will...

  9. TILT-BASED PREDICTIVE TEXT INPUT CONCEPT FOR MOBILE DEVICES

    Directory of Open Access Journals (Sweden)

    Marcin Badurowicz

    2017-06-01

    Full Text Available In the paper authors are introducing the concept of usage of physical orientation of a mobile device, calculated using built-in environmental sensors like accelerometer, gyroscope and magnetometer for detection of tilting gesture. This gesture is used as an acceptance factor for the two next probable word solutions suggested to the user during text input. By performing the device tilt, the first or second word is being automatically put into the desired text field and new prediction is performed. The text predictions are calculated and stored directly on the device to maintain privacy protection. The founding concept of the software is being presented, as well as initial considerations and further plans. This solution is recommended especially to smartphone manufacturers like Microsoft, Samsung and Apple to deploy in their latest models.

  10. Source tilting within the difference formulation for radiation transport

    Energy Technology Data Exchange (ETDEWEB)

    Luu, T; Brooks, E; Szoke, A

    2006-09-27

    We apply a heuristic technique known as 'source tilting' to a Monte Carlo solution for radiation transport, in the difference formulation, that otherwise employs a piecewise-constant treatment of the material temperature. Source tilting improves the accuracy of the piecewise-constant treatment, reducing the excessive energy flow that occurs in the thick limit. An analysis of the cause of excessive energy flow suggests an interpolation scheme that removes this defect, obtaining the correct diffusion limit flux between zones. The results obtained with our interpolation scheme agree almost identically to those of a self-consistent piecewise-linear treatment of the difference formulation while avoiding its additional costs. The resulting method is capable of providing robust and accurate calculations for problems involving optically thick zones. We comment on the monotonicity issues that arise when employing this transport method.

  11. 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.

  12. 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.

  13. Can pelvic tilting be ignored in total hip arthroplasty?

    Directory of Open Access Journals (Sweden)

    Won Yong Shon

    2014-01-01

    CONCLUSION: The sagittal position of pelvis is a key factor in impingement and dislocation after total hip arthroplasty. Pelvic tilting affects the position of acetabular component in the sagittal plane of the body as compared with its anatomic position in the pelvis. We suggest a preoperative lateral view of spine-pelvis, in upright and supine position for evaluation of a corrective adaptation of the acetabular cup accordingly with pelvic balance.

  14. The Tilt between Acretion Disk and Stellar Disk

    Indian Academy of Sciences (India)

    ... large sample of Type 2 AGNs selected from Sloan Digital Sky Survey (SDSS, York et al. 2000) to a control galaxy sample. Given that the Type 2 AGN fraction is in the range of 70–90 percent for low luminosity AGNs as a priori, we find that the mean tilt between the accretion disk and stellar disk is ∼ 30 degrees (Shen et al.

  15. determination of determination of optimal tilt angle for maximum

    African Journals Online (AJOL)

    eobe

    The energy output of photovoltaic (PV) module at different tilt angles is presented in this paper. Enugu, the study area lies within area lies within Latitude 6. Latitude 6o40'55.3”N & longitude 70 27'42.42''E. 27'42.42''E and is located in southern Nigeria. The paper located in southern Nigeria. The paper analyses the solar ...

  16. Anisotropic cosmology and inflation from a tilted Bianchi IX model

    Science.gov (United States)

    Sundell, P.; Koivisto, T.

    2015-12-01

    The dynamics of the tilted axisymmetric Bianchi IX cosmological models are explored allowing energy flux in the source fluid. The Einstein equations and the continuity equation are presented treating the equation of state w and the tilt angle of the fluid λ as time-dependent functions, but when analyzing the phase space w and λ are considered free parameters and the shear, the vorticity and the curvature of the spacetime span a three-dimensional phase space that contains seven fixed points. One of them is an attractor that inflates the universe anisotropically, thus providing a counterexample to the cosmic no-hair conjecture. Also, examples of realistic though fine-tuned cosmologies are presented wherein the rotation can become significant towards the present epoch but the shear stays within the observational bounds. The examples suggest that the model used here can explain the parity-violating anomalies of the cosmic microwave background. The result significantly differs from an earlier study, where a nonaxisymmetric Bianchi IX type model with a tilted perfect dust source was found to induce too much shear for observationally significant vorticity.

  17. Analytic crack solutions for tilt fields around hydraulic fractures

    Energy Technology Data Exchange (ETDEWEB)

    Warpinski, N.R.

    2000-01-05

    The recent development of downhole tiltmeter arrays for monitoring hydraulic fractures has provided new information on fracture growth and geometry. These downhole arrays offer the significant advantages of being close to the fracture (large signal) and being unaffected by the free surface. As with surface tiltmeter data, analysis of these measurements requires the inversion of a crack or dislocation model. To supplement the dislocation models of Davis [1983], Okada [1992] and others, this work has extended several elastic crack solutions to provide tilt calculations. The solutions include constant-pressure 2D, penny-shaped, and 3D-elliptic cracks and a 2D-variable-pressure crack. Equations are developed for an arbitrary inclined fracture in an infinite elastic space. Effects of fracture height, fracture length, fracture dip, fracture azimuth, fracture width and monitoring distance on the tilt distribution are given, as well as comparisons with the dislocation model. The results show that the tilt measurements are very sensitive to the fracture dimensions, but also that it is difficult to separate the competing effects of the various parameters.

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

    Science.gov (United States)

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

    2017-04-01

    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.

  19. The response of open channel aqueduct water levels to local and regional tilt fields

    Science.gov (United States)

    Leary, P. C.

    1981-04-01

    Simple hydraulics of open channel water flow is used to find the water level response to earth tilt along the 200 km long Los Angeles Aqueduct. The water level changes are shown to depend on the length scale of the tilt field. Tilts over lengths greater than 10 km permit the water to assume an essentially equilibrium level throughout the tilt field; change in water depth is therefore directly proportional to the degree of slope change. Tilts occurring on length scales shorter than 10 km require the use of an integral relation between tilt and water depth. The relation is used to model a tilt field corresponding to an anomalous water level event observed on the Los Angeles Aqueduct.

  20. Improvement of Head-Up Display Standards. Volume 1. Head-Up Display Design Guide. Appendix

    Science.gov (United States)

    1987-09-01

    LANDING, NASA CR-189, 1964 31 L. Collins, "Bendix Microvision ," AIR FACTS, September 1964 32 T. Gold, FLIGHT CONTROL SYSTEM, US Patent 3,128,623, April... Microvision ," US ARMY AVIATION DIGEST, December 1964, pp. 8-9 38 J. M. Naish, SYSTEM FOR PRESENTING STEERING INFORMATION DUR- ING VISUAL FLIGHT. PART III...PERSPECTIVE POLE-TRACK, SAAB TN-58, 1965 53 P. A. Noxon, " Microvision : A Universal All-Weather Landing, Station Keeping and Navigational System," JOURNAL OF

  1. Postural configuration affects the perception of earth-based space during pitch tilt.

    Science.gov (United States)

    Bourrelly, A; Vercher, J-L; Bringoux, L

    2011-09-01

    This study investigates the relative contribution of body parts in the elaboration of a whole-body egocentric attraction phenomenon previously observed during earth-based judgments. This was addressed through a particular earth-based task requiring estimating the possibility of passing under a projected line, imagining a forward horizontal displacement. Different postural configurations were tested, involving whole-body tilt, trunk tilt alone or head tilt alone. Two legs positions relative to the trunk were manipulated. Results showed systematic deviations of the subjective "passability" toward the tilt, linearly related to the tilt magnitude. For each postural configuration, the egocentric influence appeared to be highly dependent on the position of trunk and head axes, whereas the legs position appeared not relevant. When compared to the whole-body tilt condition, tilting the trunk alone consistently reduced the amount of the deviation toward the tilt, whereas tilting the head alone consistently increased it. Our results suggest that several specific effects from multiple body parts can account for the global deviation of the estimates observed during whole-body tilt. Most importantly, we support that the relative contribution of the body segments could mainly depend on a reweighting process, probably based on the reliability of sensory information available for a particular postural set. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Numerical simulation about orthogonal single frequency dithering technique used in tilt control of fiber laser array

    Science.gov (United States)

    Zhang, Zhixin; Zhi, Dong; Ma, Yanxing; Wang, Xiaolin; Zhou, Pu; Si, Lei

    2017-01-01

    Beam combination of fiber laser array is an effective technique contributed to improve the brightness of fiber lasers. In order to realize high-efficiency CBC, challenges like phase distortion (mainly including piston and tilt phase aberrations) should be taken into consideration. Resent years, tilt phase aberrations control has been come true by adaptive fiber optics collimator using the stochastic parallel gradient descent (SPGD) algorithm. However, the convergence rate of tilt control system still cannot satisfy the needs of practical application. In order to increase the tilt control bandwidth, a new idea is put forward that applying the orthogonal single frequency dithering (OSFD) technique into tilt control, and numerical simulation has been completed. A hexagonal laser array with 7 elements has been simulated, and each element has a pair of initial tilt angles in horizontal and vertical direction. The initial tilt angles comply with normal distribution. In the same condition, tilt phase control has been realized through SPGD and OSFD individually, and the convergence steps (defined as the iteration steps that improve the normalized PIB above 0.9) with appropriate parameters are respectively about 20 (SPGD) and 7 (OSFD). Furthermore, tilt phase control of large number hexagonal array is simulated, and the results are as follows: for 19/37 elements, the least convergence steps are about 80/160(SPGD) and 19/55(OSFD). Comparing with SPGD algorithm, it is obvious that the OSFD has higher convergence rate and greater potential for tilt control application in large number coherent fiber laser array.

  3. Development and testing of a pelvic goniometer designed to measure pelvic tilt and hip flexion.

    Science.gov (United States)

    Sprigle, Stephen; Flinn, Nannette; Wootten, Mary; McCorry, Stephanie

    2003-06-01

    To determine the reliability and validity of a pelvic goniometer designed to measure the pelvic tilt and hip flexion during seated posture. Assessment of the seated posture requires measurement of the pelvis and hip. Determining accurate pelvic tilt and hip flexion angles during sitting is often difficult using standard techniques. A pelvic goniometer has been designed to measure pelvic tilt and hip flexion angle of persons in a seated posture. VALIDATION of the pelvic goniometer was done radiographically. Ten male volunteers sat in three postures--erect, forward or anterior tilt, and posterior tilt. Pelvic tilt and hip angle were recorded using radiographs and the pelvic goniometer. Reliability of pelvic and conventional goniometers was done using seated nondisabled subjects with physical therapists performing measurements. the average differences and correlation between the pelvic goniometer and radiographic measures were as follows--pelvic tilt: -4.9 degrees, 0.93; hip angle 1.2 degrees, 0.81. Reliability: average range of hip angle across three measures was about 3 degrees for both goniometers. The data indicate that the pelvic goniometer has utility in measuring pelvic tilt and hip angle, especially within the seated posture. Because it measures both pelvic tilt and hip angle, the pelvic goniometer has an advantage over conventional goniometers that only measure the latter. A valid and reliable tool that measures pelvic tilt and hip angle of persons in a seated posture is needed for clinical research and practice. Its applications include wheelchair seating evaluations and ergonomic assessments of seated workers.

  4. Random Vibration Analysis of the Tip-tilt System in the GMT Fast Steering Secondary Mirror

    Science.gov (United States)

    Lee, Kyoung-Don; Kim, Young-Soo; Kim, Ho-Sang; Lee, Chan-Hee; Lee, Won Gi

    2017-09-01

    A random vibration analysis was accomplished on the tip-tilt system of the fast steering secondary mirror (FSM) for the Giant Magellan Telescope (GMT). As the FSM was to be mounted on the top end of the secondary truss and disturbed by the winds, dynamic effects of the FSM disturbances on the tip-tilt correction performance was studied. The coupled dynamic responses of the FSM segments were evaluated with a suggested tip-tilt correction modeling. Dynamic equations for the tip-tilt system were derived from the force and moment equilibrium on the segment mirror and the geometric compatibility conditions with four design parameters. Statically stationary responses for the tip-tilt actuations to correct the wind-induced disturbances were studied with two design parameters based on the spectral density function of the star image errors in the frequency domain. Frequency response functions and root mean square values of the dynamic responses and the residual star image errors were numerically calculated for the off-axis and on-axis segments of the FSM. A prototype of on-axis segment of the FSM was developed for tip-tilt actuation tests to confirm the ratio of tip-tilt force to tip-tilt angle calculated from the suggested dynamic equations of the tip-tilt system. Tip-tilt actuation tests were executed at 4, 8 and 12 Hz by measuring displacements of piezoelectric actuators and reaction forces acting on the axial supports. The derived ratios of rms tip-tilt force to rms tip-tilt angle from tests showed a good correlation with the numerical results. The suggested process of random vibration analysis on the tip-tilt system to correct the wind-induced disturbances of the FSM segments would be useful to advance the FSM design and upgrade the capability to achieve the least residual star image errors by understanding the details of dynamics.

  5. EXPERIMENTAL MEASUREMENTS OF TOWER CONSTRUCTION TILT USING ELECTRONIC TACHEOMETER

    Directory of Open Access Journals (Sweden)

    V. I. Mikhailov

    2015-01-01

    Full Text Available Modern tendencies for assessment of high-rise building deformation state presuppose creation of automated and regular monitoring while using highly-accurate space positioning systems (GPS-systems, a robotic electronic tacheometer, highlyaccurate inclinators (Leica Nivel210/Nivel220-model with measuring accuracy of tilt angle up to 0.09 s, Geomos software complex (Leica Geosystems. Automated system for deformation monitoring requires significant time and material expenditures, special training of specialists so simpler methods and criteria for assessment of building deformation state are also considered as rather actual for this purpose.There are more than ten conventional methods for determining building tilt. All these methods are based on angular measurements from the fixed base while using highly-accurate theodolites. The methods are rather labor-consuming and they do not provide operational efficiency and accuracy in measurements. Introduction of electronic tacheometers with large radius of refractorless measurements of distances has made it possible to calculate coordinates on the building surface with high accuracy and at various sections (heights that results in possibility to obtain 3D model of the building surface. Leica TCRA1201 tacheometer has been set at the good visibility point of a tower construction, device orientation and plane coordinates of the temporary point have been determined with the purpose to assess a tilt value of an exhaust stack having 150 meter height. Then 3D coordinates of six points on the building surface have been measured for every stack section. After that these points have been projected on the horizontal plane. LISCAD PLUS software complex has been used for processing and interpretation of geodetic data.The proposed method permits to obtain data for determination value and direction of a tower construction tilt, immediately carry out in-situ measurements and obtain final results in the automatic mode of

  6. 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.

  7. Three-parameter tunable Tilt-Integral-Derivative (TID) controller

    Science.gov (United States)

    Lurie, Boris J. (Inventor)

    1994-01-01

    A feedback control system compensator of the PID type is provided, wherein the proportional component of the compensator is replaced with a tilted component having a transfer function s to the power of -1/n. The resulting transfer function of the entire compensator more closely approximates an optimal transfer function, thereby achieving improved feedback controller. Further, as compared to conventional PID compensators, the TID compensator allows for simpler tuning, better disturbance rejection ratio, and smaller effects of plant parameter variations on closed loop response.

  8. Tilted versus axially placed dental implants: a meta-analysis.

    Science.gov (United States)

    Chrcanovic, Bruno Ramos; Albrektsson, Tomas; Wennerberg, Ann

    2015-02-01

    The purpose of the present review was to test the null hypothesis of no difference in the implant failure rate, marginal bone loss, and postoperative infection for patients being rehabilitated by tilted or by axially placed dental implants, against the alternative hypothesis of a difference. An electronic search without time or language restrictions was undertaken in July 2014. Eligibility criteria included clinical human studies, either randomised or not, interventional or observational. The estimates of an intervention were expressed in risk ratio (RR) and mean difference (MD) in millimetres. The search strategy resulted in 44 publications. A total of 5029 dental implants were tilted (82 failures; 1.63%), and 5732 implants were axially placed (104 failures; 1.81%). The difference between the procedures did not significantly affect the implant failure rates (P=0.40), with a RR of 1.14 (95% CI 0.84-1.56). A statistically significant difference was found for implant failures when studies evaluating implants inserted in maxillae only were pooled (RR 1.70, 95% CI 1.05-2.74; P=0.03), the same not happening for the mandible (RR 0.77, 95% CI 0.39-1.52; P=0.45). There were no apparent significant effects of tilted dental implants on the occurrence of marginal bone loss (MD 0.03, 95% CI -0.03 to 0.08; P=0.32). Due to lack of satisfactory information, meta-analysis for the outcome 'postoperative infection' was not performed. It is suggested that the differences in angulation of dental implants might not affect the implant survival or the marginal bone loss. The reliability and validity of the data collected and the potential for biases and confounding factors are some of the shortcomings of the present study. The question whether tilted implants are more at risk for failure than axially placed implants has received increasing attention in the last years. As the philosophies of treatment alter over time, a periodic review of the different concepts is necessary to refine

  9. View Angle Tilting Echo Planar Imaging for Distortion Correction

    OpenAIRE

    Ahn, Sinyeob; Hu, Xiaoping

    2011-01-01

    Geometric distortion caused by field inhomogeneity along the phase-encode (PE) direction is one of the most prominent artifacts due to a relatively low effective bandwidth along that direction in magnetic resonance echo planar imaging (EPI). This work describes a method for correcting in-plane image distortion along the PE direction using a view angle tilting (VAT) imaging technique in spin-echo EPI (SE-EPI). SE-EPI with VAT (SE-EPI-VAT) utilizes the addition of gradient blips along the slice...

  10. A three-step least-squares iterative method for tilt phase-shift interferometry.

    Science.gov (United States)

    Liu, Qian; Wang, Yang; Ji, Fang; He, Jianguo

    2013-12-02

    An iterative method based on least-squares fittings is proposed to retrieve wavefront phase from tilt phase-shift interferograms. In each iteration cycle, proposed method calculates wavefront phase and tilt phase shifts in x- and y-directions in three individual least-squares fitting steps. In tilt phase shifts extracting steps, phase shifts of interferograms columns or rows are calculated with least-squares method, and then tilt phase shifts of interferograms in x- or y-direction are determined by linear regressions. At least three interferograms of three by three pixels are required with proposed method. The performance of proposed method is demonstrated by simulations and experiments. Tilt gradients and translational phase shifts could be extracted with high accuracy and large wavefront tilts could be well handled with proposed method. The method could be applied to temporal phase-shift interferometers with uncalibrated transducers or that in vibrating environment.

  11. A new sagittal parameter to estimate pelvic tilt using the iliac cortical density line and iliac tilt: a retrospective X-ray measurement study.

    Science.gov (United States)

    Doi, Toshio; Tono, Osamu; Tarukado, Kiyoshi; Harimaya, Katsumi; Matsumoto, Yoshihiro; Hayashida, Mitsumasa; Okada, Seiji; Iwamoto, Yukihide

    2015-07-22

    When spinal kyphosis increases, the compensatory mechanism activates and the pelvic position changes. Increasing the pelvic tilt, which is the orientation of the pelvis with respect to the femoral head, is known to associate with the clinical symptoms in kyphosis in the aging population. It is often difficult to detect the femoral head on radiographs, limiting the ability to determine the pelvic tilt. Therefore, there is a need to establish another parameter independent of the femoral head which closely correlates with the pelvic tilt. Eighty-two adult patients with full-length lateral standing spine radiographs were recruited (mean age: 73.0 years). A new parameter, the iliac cortical density line (a component of the arcuate line of the ilium) and the iliac tilt (defined as the angle between the iliac cortical density line and the vertical), was analyzed to determine the correlation with the pelvic tilt. Both the pelvic tilt (PT) and iliac tilt (IT) could be identified in 67 patients, and a significant correlation was observed between the PT and IT (r = 0.86, P head is not detectable on the radiograph.

  12. Characterizing local variability in long‐period horizontal tilt noise

    Science.gov (United States)

    Rohde, M.D.; Ringler, Adam; Hutt, Charles R.; Wilson, David; Holland, Austin; Sandoval, L.D; Storm, Tyler

    2017-01-01

    Horizontal seismic data are dominated by atmospherically induced tilt noise at long periods (i.e., 30 s and greater). Tilt noise limits our ability to use horizontal data for sensitive seismological studies such as observing free earth modes. To better understand the local spatial variability of long‐period horizontal noise, we observe horizontal noise during quiet time periods in the Albuquerque Seismological Laboratory (ASL) underground vault using four small‐aperture array configurations. Each array comprises eight Streckeisen STS‐2 broadband seismometers. We analyze the spectral content of the data using power spectral density and magnitude‐squared coherence (γ2‐coherence). Our results show a high degree of spatial variability and frequency dependence in the long‐period horizontal wavefield. The variable nature of long‐period horizontal noise in the ASL vault suggests that it might be highly local in nature and not easily characterized by simple physical models when overall noise levels are low, making it difficult to identify locations in the vault with lower horizontal noise. This variability could be limiting our ability to apply coherence analysis for estimating horizontal sensor self‐noise and could also complicate various indirect methods for removing long‐period horizontal noise (e.g., collocated rotational sensor or microbarograph).

  13. 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

  14. 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.

  15. Tracking of flying insects using pan-tilt cameras.

    Science.gov (United States)

    Fry, S N; Bichsel, M; Müller, P; Robert, D

    2000-08-15

    Potent and affordable video and computer systems for automatic data acquisition are becoming increasingly important in behavioural neuroscience. It has remained challenging, however, to acquire data from small and fast-moving animals, such as insects in flight, due to the limited spatial and temporal resolution of the systems currently available. Our research on free-flying insects motivated the development of new methods in the context of two different experimental settings. First, the position and precise body axis direction of honey bees approaching a food source were automatically measured. Second, the flight trajectories of a phonotactic parasitoid fly homing in on its cricket host were recorded in 3D. We used pan-tilt cameras, i.e. cameras with moveable optics, to follow the animal's path with a close up image. Novel methods were developed for image acquisition and position measurement using pan-tilt cameras, as well as calibration and data evaluation in 3D world coordinates. The innovations of this system comprise: (1) Acquisition of images in high spatial detail over large observation areas. (2) Image acquisition at a field rate of 50 Hz PAL. (3) Free positioning of the cameras for 3D acquisition. (4) Computation of the flight path in 3D world coordinates. We illustrate the capabilities of the system with data obtained from a calibration object as well as from the behaviour of unrestricted, free-flying flies and bees. Potential applications in behavioural neuroscience and the psychophysics of sensory perception are briefly discussed.

  16. Tilt recorded by a portable broadband seismograph: The 2003 eruption of Anatahan Volcano, Mariana Islands

    Science.gov (United States)

    Wiens, D.A.; Pozgay, S.H.; Shore, P.J.; Sauter, A.W.; White, R.A.

    2005-01-01

    The horizontal components of broadband seismographs are highly sensitive to tilt, suggesting that commonly deployed portable broadband seismic sensors may record important tilt information associated with volcanic eruptions. We report on a tilt episode that coincides with the first historical eruption of Anatahan volcano on May 10, 2003. The tilt was recorded by a Strekheisen STS-2 seismograph deployed in an underground insulated chamber 7 km west of the active vent. An ultra-long period signal with a dominant period of several hours was recorded on the E-W component beginning at 06:20 GMT on May 10, which coincides with the onset of continuous volcano-tectonic (VT) seismicity and is one hour prior to the eruption time estimated by the Volcanic Ash Advisory Center. The signal is much smaller on the N-S component and absent on the vertical component, suggesting it results from tilt that is approximately radial with respect to the active vent. An estimate of tilt as a function of time is recovered by deconvolving the record to acceleration and dividing by the acceleration of gravity. The record indicates an initial episode of tilt downward away from the volcanic center from 06:20-09:30 GMT, which we interpret as inflation of the shallow volcanic source. The tilt reverses, recording deflation, from 09:30 until 17:50, after which the tilt signal becomes insignificant. The inflation corresponds to a period of numerous VT events, whereas fewer events were recorded during the deflation episode, and the VT events subsequently resumed after the end of the deflationary tilt. The maximum tilt of 2 microradians can be used to estimate the volume of the source inflation (???2 million in m3), assuming a simple Mogi source model. These calculations are consistent with other estimates of source volume if reasonable source depths are assumed. Examination of broadband records of other eruptions may disclose further previously unrecognized tilt signals. Copyright 2005 by the American

  17. Tapered tilted linear zone plates for focusing hard x-rays

    Science.gov (United States)

    Ocola, Leonidas E.; Maser, Joerg; Vogt, Stefan; Lai, Barry; Divan, Ralu; Stephenson, Gregory B.

    2004-11-01

    We introduce a new design of tilted linear zone plates, which are named tapered tilted linear (TTL) zone plates. The purpose of the design is to increase efficiency while at the same time keeping the focal plane perpendicular to the optical path. In order to accomplish this, the zone radius and number of zones must become a function of position along the structure. Simulation work described in this paper shows improved optical performance over regular tilted linear zone plates.

  18. Phase shifting interferometry from two normalized interferograms with random tilt phase-shift.

    Science.gov (United States)

    Liu, Fengwei; Wu, Yongqian; Wu, Fan

    2015-07-27

    We propose a novel phase shifting interferometry from two normalized interferograms with random tilt phase-shift. The determination of tilt phase-shift is performed by extracting the tilted phase-shift plane from the phase difference of two normalized interferograms, and with the calculated tilt phase-shift value the phase distribution can be retrieved from the two normalized frames. By analyzing the distribution of phase difference and utilizing special points fitting method, the tilted phase-shift plane is extracted in three different cases, which relate to different magnitudes of tilts. Proposed method has been applied to simulations and experiments successfully and the satisfactory results manifest that proposed method is of high accuracy and high speed compared with the three step iterative method. Additionally, both open and closed fringe can be analyzed with proposed method. What's more, it cannot only eliminate the small tilt-shift error caused by slight vibration in phase-shifting interferometry, but also detect the large tilt phase-shift in phase-tilting interferometry. Thus, it will relaxes the requirements on the accuracy of phase shifter, and the costly phase shifter may even be useless by applying proposed method in high amplitude vibrated circumstance to achieve high-precision analysis.

  19. Direct experimental measurement of SRS-induced spectral tilt in multichannel multispan communication systems

    Energy Technology Data Exchange (ETDEWEB)

    Kapin, Yu A; Nanii, Oleg E; Novikov, A G; Pavlov, V N; Plotskii, A Yu; Treshchikov, V N

    2012-09-30

    Nonlinear SRS-induced tilt of the spectrum of a multichannel DWDM signal is studied experimentally in standard singlemode fibreoptic communication lines. It is found that at a fixed spectral bandwidth and total power the nonlinear SRS tilt is independent of the number of channels, radiation source type, and the initial tilt (positive or negative). In a multispan line consisting of identical spans the total nonlinear tilt of the spectrum (in dB) is proportional to the number of spans, spectral width and total power. (optical fibres, lasers and amplifiers. properties and applications)

  20. Use of an Android application "clinometer" for measurement of head down tilt given during subarachnoid block

    Directory of Open Access Journals (Sweden)

    R B Dixit

    2016-01-01

    Results: We observed that the application was easy to use and measured tilt each time. The result obtained can be documented, digitally saved and transferred. In 130 patients studied, we observed incidence of degree of tilt as follows: 6-8° tilt in 38 patients (29.23%, 8-10 in 36 patients (27.69%, 10-12 in 30 patients (23.08%, 12-14 in 12 patients (9.23% and 14-16° tilt in 14 patients (10.77%. Use of application was received with enthusiasm by practicing anesthesiologists. Various possible uses of this application are discussed.

  1. The effects of gantry tilt on breast dose and image noise in cardiac CT

    Energy Technology Data Exchange (ETDEWEB)

    Hoppe, Michael E.; Gandhi, Diksha; Schmidt, Taly Gilat [Department of Biomedical Engineering, Marquette University, Milwaukee, Wisconsin 53233 (United States); Stevens, Grant M. [GE Healthcare, Waukesha, Wisconsin 53188 (United States); Foley, W. Dennis [Department of Radiology, Medical College of Wisconsin, Froedtert Memorial Lutheran Hospital, Milwaukee, Wisconsin 53226 (United States)

    2013-12-15

    Purpose: This study investigated the effects of tilted-gantry acquisition on image noise and glandular breast dose in females during cardiac computed tomography (CT) scans. Reducing the dose to glandular breast tissue is important due to its high radiosensitivity and limited diagnostic significance in cardiac CT scans.Methods: Tilted-gantry acquisition was investigated through computer simulations and experimental measurements. Upon IRB approval, eight voxelized phantoms were constructed from previously acquired cardiac CT datasets. Monte Carlo simulations quantified the dose deposited in glandular breast tissue over a range of tilt angles. The effects of tilted-gantry acquisition on breast dose were measured on a clinical CT scanner (CT750HD, GE Healthcare) using an anthropomorphic phantom with MOSFET dosimeters in the breast regions. In both simulations and experiments, scans were performed at gantry tilt angles of 0°–30°, in 5° increments. The percent change in breast dose was calculated relative to the nontilted scan for all tilt angles. The percent change in noise standard deviation due to gantry tilt was calculated in all reconstructed simulated and experimental images.Results: Tilting the gantry reduced the breast dose in all simulated and experimental phantoms, with generally greater dose reduction at increased gantry tilts. For example, at 30° gantry tilt, the dosimeters located in the superior, middle, and inferior breast regions measured dose reductions of 74%, 61%, and 9%, respectively. The simulations estimated 0%–30% total breast dose reduction across the eight phantoms and range of tilt angles. However, tilted-gantry acquisition also increased the noise standard deviation in the simulated phantoms by 2%–50% due to increased pathlength through the iodine-filled heart. The experimental phantom, which did not contain iodine in the blood, demonstrated decreased breast dose and decreased noise at all gantry tilt angles.Conclusions: Tilting the

  2. 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...... entirely PEEK pads are investigated to determine the effect of varying mean bearing pressure and pivot characteristics as well as different material properties of the polymer layer. Experimental results indicate increased damping and decreased stiffness and slightly increased oil film temperature...... for entirely PEEK pads compared to pads with a PEEK lining and steel backing. Similar effects were observed by using a softer (PTFE) pad liner with a steel backing....

  3. Flow tilt angles near forest edges - Part 2: Lidar anemometry

    DEFF Research Database (Denmark)

    Dellwik, Ebba; Mann, Jakob; Bingöl, Ferhat

    2010-01-01

    ) a fetch-limited beech forest site taken at 48–175 m a.g.l. (above ground level), (2) a reference site in flat agricultural terrain and (3) a second reference site in complex terrain are presented. The method to derive flow tilt angles and mean vertical velocities from lidar has several advantages compared...... 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...... vertical velocity, whereas the error due to flow inhomogeneity on the horizontal mean wind speed is independent of the lidar beam angle. For the presented measurements over forest, it is evaluated that the systematic error due to the inhomogeneity of the flow is less than 0.2°. The results of the vertical...

  4. 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...

  5. 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.

  6. Low energy planes for tilt grain boundaries in gold

    Energy Technology Data Exchange (ETDEWEB)

    Goodhew, P. J.; Tan, T. Y.; Balluffi, R. W.

    1977-05-01

    Thin film bicrystals of gold were annealed to create a large variety of grain boundaries of controlled crystal misorientation. The faceting of these boundaries was studied, and some low-energy boundary planes were identified. Tilt boundaries with a (100) misorientation axis were found to facet more readily than those with a (100) axis. The results were considered in terms of O-lattices and coincident site lattices, but neither of these approaches is able to explain all the observations. Consequently, no simple and general criteria, based on geometrical considerations, were found for the occurrence of grain boundary planes of low energy. A further set of observations relates to the dissociation of some specific high-angle grain boundaries into a twin and another low-energy boundary. Boundaries with a ..sigma..33 coincidence site lattice relationship frequently appear to be characterized by a relatively low energy. 12 figures, 2 tables.

  7. TIRF microscopy evanescent field calibration using tilted fluorescent microtubules.

    Science.gov (United States)

    Gell, C; Berndt, M; Enderlein, J; Diez, S

    2009-04-01

    Total internal reflection fluorescence microscopy has become a powerful tool to study the dynamics of sub-cellular structures and single molecules near substrate surfaces. However, the penetration depth of the evanescent field, that is, the distance at which the excitation intensity has exponentially decayed to 1/e, is often left undetermined. This presents a limit on the spatial information about the imaged structures. Here, we present a novel method to quantitatively characterize the illumination in total internal reflection fluorescence microscopy using tilted, fluorescently labelled, microtubules. We find that the evanescent field is well described by a single exponential function, with a penetration depth close to theoretically predicted values. The use of in vitro reconstituted microtubules as nanoscale probes results in a minimal perturbation of the evanescent field; excitation light scattering is eliminated and the refractive index of the sample environment is unchanged. The presented method has the potential to provide a generic tool for in situ calibration of the evanescent field.

  8. Tilt-rotor flutter control in cruise flight

    Science.gov (United States)

    Nasu, Ken-Ichi

    1986-01-01

    Tilt-rotor flutter control under cruising operation is analyzed. The rotor model consists of a straight fixed wing, a pylon attached to the wingtip, and a three-blade rotor. The wing is cantilevered to the fuselage and is allowed to bend forward and upward. It also has a torsional degree of freedom about the elastic axis. Each rotor blade has two bending degrees of freedom. Feedback of wingtip velocity and acceleration to cyclic pitch is investigated for flutter control, using strip theory and linearized equations of motion. To determine the feedback gain, an eigenvalue analysis is performed. A second, independent, timewise calculation is conducted to evaluate the control law while employing more sophisticated aerodynamics. The effectiveness of flutter control by cyclic pitch change was confirmed.

  9. Comparison of scapular posterior tilting exercise alone and scapular posterior tilting exercise after pectoralis minor stretching on scapular alignment and scapular upward rotators activity in subjects with short pectoralis minor.

    Science.gov (United States)

    Lee, Ji-Hyun; Cynn, Heon-Seock; Yoon, Tae-Lim; Choi, Sil-Ah; Choi, Woo-Jeong; Choi, Bong-Sam; Ko, Chang-Hee

    2015-08-01

    To compare scapular posterior tilting exercise alone and scapular posterior tilting exercise after pectoralis minor (PM) stretching on the PM index (PMI), scapular anterior tilting index, scapular upward rotation angle, and scapular upward rotators' activity in subjects with a short PM. Fifteen subjects with a short PM participated in this study. The PMI, scapular anterior tilting index, and scapular upward rotation angle were measured after scapular posterior tilting exercise alone and scapular posterior tilting exercise after PM stretches. Scapular upward rotators' activities were collected during scapular posterior tilting exercise alone and scapular posterior tilting exercise after PM stretches. The PMI and scapular upward rotation angle, as well as the activity of the upper trapezius, lower trapezius, and serratus anterior muscles, were significantly greater for scapular posterior tilting exercise after PM stretching and the scapular anterior tilting index was significantly lower for scapular posterior tilting exercise after PM stretching than the scapular posterior tilting exercise alone. Scapular posterior tilting exercise after PM stretching in subjects with a short PM could be an effective method of modifying scapular alignment and scapular upward rotator activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. impact of mechanical down tilt and height on the pilot coverage of ...

    African Journals Online (AJOL)

    2012-12-09

    Dec 9, 2012 ... In this paper, the impacts of antenna mechanical down tilt and antenna height on UMTS network performance are studied. First, we used ASSET3G simulation. software to design 36 pilot coverage. ..... decreases with increase in the tilt angle until alter i kin distance when the power level remains the same.

  11. Implementation of a cryo-electron tomography tilt-scheme optimized for high resolution subtomogram averaging.

    Science.gov (United States)

    Hagen, Wim J H; Wan, William; Briggs, John A G

    2017-02-01

    Cryo-electron tomography (cryoET) allows 3D structural information to be obtained from cells and other biological samples in their close-to-native state. In combination with subtomogram averaging, detailed structures of repeating features can be resolved. CryoET data is collected as a series of images of the sample from different tilt angles; this is performed by physically rotating the sample in the microscope between each image. The angles at which the images are collected, and the order in which they are collected, together are called the tilt-scheme. Here we describe a "dose-symmetric tilt-scheme" that begins at low tilt and then alternates between increasingly positive and negative tilts. This tilt-scheme maximizes the amount of high-resolution information maintained in the tomogram for subsequent subtomogram averaging, and may also be advantageous for other applications. We describe implementation of the tilt-scheme in combination with further data-collection refinements including setting thresholds on acceptable drift and improving focus accuracy. Requirements for microscope set-up are introduced, and a macro is provided which automates the application of the tilt-scheme within SerialEM. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  12. Optimum Tilt Angle for Photovoltaic Solar Panels in Zomba District, Malawi

    Directory of Open Access Journals (Sweden)

    B. Kamanga

    2014-01-01

    Full Text Available A study to determine the optimum tilt angle for installing photovoltaic solar panels in Zomba district, Malawi, has been conducted. The study determined the optimum monthly tilt angles of PV solar panels and the seasonal adjustments needed for the panels in order to collect maximum solar radiation throughout the year. In this study, global solar radiation (GSR on four tilted surfaces was measured. The north-facing surfaces were titled at angles of 0°, 15°, 20°, and 25°. The GSR data was used to determine the daily and monthly optimum tilt angles for the PV panels. The optimum tilt angles were found to be 0° or 25° depending on the time of the year. From October to February, the optimum tilt angle has been determined to be 0° and, from March to September, the optimum tilt angle is observed to be 25°. There are only two seasonal adjustments that are needed for PV solar panels in Zomba district and these should be carried out at the end of February and at the end of September. For fixed solar panels with no seasonal adjustments, the optimum tilt angle for the PV solar panels that are northfacing has been determined to be 25°.

  13. Patients with severe acquired brain injury show increased arousal in tilt-table training

    DEFF Research Database (Denmark)

    Riberholt, Christian Gunge; Thorlund, Jonas Bloch; Mehlsen, Jesper

    2013-01-01

    Patients with severe acquired brain injury (ABI) are often mobilised using a tilt-table. Complications such as orthostatic intolerance have been reported. The primary objective of this study was to investigate if using a tilt-table was feasible for mobilising patients with severe ABI admitted...

  14. 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.

  15. 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'

  16. 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

  17. Validation of Tilt Gain under Realistic Path Loss Model and Network Scenario

    DEFF Research Database (Denmark)

    Nguyen, Huan Cong; Rodriguez, Ignacio; Sørensen, Troels Bundgaard

    2013-01-01

    Despite being a simple and commonly-applied radio optimization technique, the impact on practical network performance from base station antenna downtilt is not well understood. Most published studies based on empirical path loss models report tilt angles and performance gains that are far higher...... than practical experience suggests. We motivate in this paper, based on a practical LTE scenario, that the discrepancy partly lies in the path loss model, and shows that a more detailed semi-deterministic model leads to both lower gains in terms of SINR, outage probability and downlink throughput...... and lower optimum tilt settings. Furthermore, we show that a simple geometrically based tilt optimization algorithm can outperform other tilt profiles, including the setting applied by the cellular operator in the specific case. In general, the network performance is not highly sensitive to the tilt...

  18. Short AV interval VDD pacing does not prevent tilt induced vasovagal syncope in patients with cardioinhibitory vasovagal syndrome.

    Science.gov (United States)

    Petersen, M E; Price, D; Williams, T; Jensen, N; Riff, K; Sutton, R; Rift K [corrected to Riff, K

    1994-05-01

    Eleven subjects (mean age 50 years, range 33-71 years), who had previously received permanent dual chamber pacemakers for cardioinhibitory vasovagal syncope, underwent paired Westminster protocol tilt tests, one with short AV delay VDD pacing and one without pacing, to test the hypothesis that continuous ventricular pacing would prevent the cardiac initiation of vasovagal syncope. Nine (82%) of the paced tilts produced positive vasovagal outcomes compared with seven (64%) of the unpaced tilts. No important differences in the heart rate or blood pressure behavior during tilt or the time to positive vasovagal outcomes were observed between the paired tilts. There was more accelerated syncope/presyncope once symptoms had developed during the paced tilts of subjects in whom both study tilts were positive, although this did not reach statistical significance (P = 0.054). This study shows that atrial synchronous ventricular pacing does not prevent the initiation, or progression, of tilt induced vasovagal syncope in predisposed subjects.

  19. Is a positive intracutaneous test induced by penicillin mediated by histamine?

    DEFF Research Database (Denmark)

    Tannert, Line K; Falkencrone, Sidsel; Mortz, Charlotte G

    2017-01-01

    Background: Diagnostic workup of penicillin allergy comprises skin testing with penicillins, and patients are deemed allergic if skin test is positive. However, the literature suggests that skin test-positive patients may be challenge-negative, indicating that the skin test may be falsely positive....... Objective: To investigate real-time histamine release from a positive intracutaneous test induced by penicillin in patients with positive and negative challenges to penicillin. Methods: Skin microdialysis was performed in 21 penicillin-allergic patients with positive skin test, 13 non-allergic volunteers...... serving as negative controls, and 7 grass pollen-allergic patients serving as positive controls. Histamine was measured by microdialysis after skin test with penicillin/grass/NaCl. Penicillin challenge was subsequently performed in 12 of the patients. Results: Only 10/21 patients (47.6%) were skin test...

  20. Visual Tilt Estimation for Planar-Motion Methods in Indoor Mobile Robots

    Directory of Open Access Journals (Sweden)

    David Fleer

    2017-10-01

    Full Text Available Visual methods have many applications in mobile robotics problems, such as localization, navigation, and mapping. Some methods require that the robot moves in a plane without tilting. This planar-motion assumption simplifies the problem, and can lead to improved results. However, tilting the robot violates this assumption, and may cause planar-motion methods to fail. Such a tilt should therefore be corrected. In this work, we estimate a robot’s tilt relative to a ground plane from individual panoramic images. This estimate is based on the vanishing point of vertical elements, which commonly occur in indoor environments. We test the quality of two methods on images from several environments: An image-space method exploits several approximations to detect the vanishing point in a panoramic fisheye image. The vector-consensus method uses a calibrated camera model to solve the tilt-estimation problem in 3D space. In addition, we measure the time required on desktop and embedded systems. We previously studied visual pose-estimation for a domestic robot, including the effect of tilts. We use these earlier results to establish meaningful standards for the estimation error and time. Overall, we find the methods to be accurate and fast enough for real-time use on embedded systems. However, the tilt-estimation error increases markedly in environments containing relatively few vertical edges.

  1. Head-shaking tilt suppression: a clinical test to discern central from peripheral causes of vertigo.

    Science.gov (United States)

    Zuma E Maia, F C; Cal, Renato; D'Albora, Ricardo; Carmona, Sergio; Schubert, Michael C

    2017-06-01

    Tilt suppression refers to both tilting the head away from an Earth vertical axis and a reduction of an induced horizontal nystagmus. This phenomenon of reducing an induced horizontal nystagmus involves a circuitry of neurons within the vestibular nuclei and the cerebellum (collectively referred to as velocity storage) and signals from the otolith end organs. Lesions involving this circuitry can disrupt tilt suppression of induced horizontal nystagmus. We investigated the clinical value of combining the horizontal head-shaking nystagmus test with tilt suppression in 28 patients with unilateral peripheral vestibular hypofunction and 11 patients with lesions affecting the central nervous system. Each of the subjects with peripheral vestibular lesions generated an appropriately directed horizontal nystagmus after head shaking that then suppressed the induced angular slow phase velocity on average 52 ± 17.6% following tilt down of the head. In contrast, patients with central lesions had very little ability to suppress post-head-shaking nystagmus (mean 3.4 ± 56%). We recommend tilting the head after head shaking as a useful clinical test to assist in the differential diagnosis of vertiginous patients. In the case of unilateral peripheral vestibular hypofunction, head tilt suppresses the induced nystagmus via influence of the otolith organ. In the case of central pathology, the inability to suppress the nystagmus is from lesions impairing the otolith mediation on the velocity storage circuitry.

  2. Tilted microstrip phased arrays with improved electromagnetic decoupling for ultrahigh-field magnetic resonance imaging.

    Science.gov (United States)

    Pang, Yong; Wu, Bing; Jiang, Xiaohua; Vigneron, Daniel B; Zhang, Xiaoliang

    2014-12-01

    One of the technical challenges in designing a dedicated transceiver radio frequency (RF) array for MR imaging in humans at ultrahigh magnetic fields is how to effectively decouple the resonant elements of the array. In this work, we propose a new approach using tilted microstrip array elements for improving the decoupling performance and potentially parallel imaging capability. To investigate and validate the proposed design technique, an 8-channel volume array with tilted straight-type microstrip elements was designed, capable for human imaging at the ultrahigh field of 7 Tesla. In this volume transceiver array, its electromagnetic decoupling behavior among resonant elements, RF field penetration to biological samples, and parallel imaging performance were studied through bench tests and in vivo MR imaging experiments. In this specific tilted element array design, decoupling among array elements changes with the tilted angle of the elements and the best decoupling can be achieved at certain tilted angle. In vivo human knee MR images were acquired using the tilted volume array at 7 Tesla for method validation. Results of this study demonstrated that the electromagnetic decoupling between array elements and the B1 field strength can be improved by using the tilted element method in microstrip RF coil array designs at the ultrahigh field of 7T.

  3. Web server for tilt-pair validation of single particle maps from electron cryomicroscopy.

    Science.gov (United States)

    Wasilewski, Sebastian; Rosenthal, Peter B

    2014-04-01

    Three-dimensional structures of biological assemblies may be calculated from images of single particles obtained by electron cryomicroscopy. A key step is the correct determination of the orientation of the particle in individual image projections. A useful tool for validation of the quality of a 3D map and its consistency with images is tilt-pair analysis. In a successful tilt-pair test, the relative angle between orientations assigned to each image of a tilt-pair agrees with the known relative rotation angle of the microscope specimen holder during the experiment. To make the procedure easy to apply to the increasing number of single particle maps, we have developed software and a web server for tilt-pair analysis. The tilt-pair analysis program reports the overall agreement of the assigned orientations with the known tilt angle and axis of the experiment and the distribution of tilt transformations for individual particles recorded in a single image field. We illustrate application of the validation tool to several single particle specimens and describe how to interpret the scores. Copyright © 2014. Published by Elsevier Inc.

  4. 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.

  5. Determination of Solar Collector Optimum Tilt Angle for Ankara and Districts

    Directory of Open Access Journals (Sweden)

    Abdülkadir KOÇER

    2016-04-01

    Full Text Available This study that is Ankara province and districts based deals with the determination of the optimum tilt angle to maximize the performances of solar collector and solar panel. In Ankara, fixed solar collectors are usually placed at slope of 40°. In this study, annual optimum tilt angle for Ankara province and districts was calculated as 34°±1 however the optimum angles during the year were calculated between 1° and 67°. The results of this study are compared with similar studies in the literature they were found to be consistent with the results of similar studies. Also, the tilt angle was calculated for the six months periods as 15° and 56°, for seasonal periods (winter, spring, summer, autumn as 62°, 23°, 6° and 49°, respectively and solar radiation for optimum angles of inclination were found. When the tilt angle is changed only twice a year, due to increasing the amount of energy per unit area, according to the annual tilt angle fixed product they provides energy efficiency by about 5%. On the other hand, when the tilt angle is changed every month this ratio can be reached approximately 8%. For increasing the utilization efficiency of solar collectors and panels, it is recommended adjusting of the tilt angle once a month or at least twice a year.

  6. Vertical vergence adaptation produces an objective vertical deviation that changes with head tilt.

    Science.gov (United States)

    Irsch, Kristina; Guyton, David L; Ramey, Nicholas A; Adyanthaya, Rohit S; Ying, Howard S

    2013-05-03

    To document the cyclovertical ocular motor mechanism used for vertical fusion in healthy subjects, and to explore whether vertical vergence training in healthy individuals can produce objectively confirmed vertical deviations that change with head tilt, revealing a basic mechanism that can produce a pattern of misalignment in an otherwise normal ocular motor system that is similar to superior oblique muscle paresis (SOP). Seven subjects with normal orthoptic examinations were adapted to vertical image disparities using our tilting haploscopic eye-tracking apparatus presenting concentric circle targets without torsional cues. Static eye positions were recorded with head straight and when tilted 45 degrees to the left and right, during both binocular and monocular viewing. Vertical fusional vergence was accompanied by a cycloversion, with the downward-moving eye intorting and the upward-moving eye extorting, implicating primary involvement of the oblique extraocular muscles. After adaptation to the slowly increasing vertical target separation, all subjects developed a temporary vertical deviation in the straight ahead position that increased with head tilt to one side and decreased with head tilt to the other side. These results not only show that head-tilt-dependent changes in vertical deviation are not necessarily pathognomonic for SOP, but also, and more importantly, suggest mechanisms that can mimic SOP and suggest a possible role for vertical vergence training in reducing deviations and thus the amount of head tilt required for fusion. Ultimately, vertical vergence training may provide an adjunct or alternative to extraocular muscle surgery in selected cases.

  7. Marginal bone loss around tilted implants in comparison to straight implants: a meta-analysis.

    Science.gov (United States)

    Monje, Alberto; Chan, Hsun-Liang; Suarez, Fernando; Galindo-Moreno, Pablo; Wang, Hom-Lay

    2012-01-01

    The primary aim of this systematic review was to compare the amount of marginal bone loss around tilted and straight implants. As the secondary aim, the incidence of biomechanic complications was compared. An electronic literature search from five databases, for the years 2000 to 2011, and a hand search in implant-related journals were conducted. Clinical human studies in the English language that had reported marginal bone loss in tilted and straight implants at 12-months follow-up or longer were included. Mean marginal bone loss and the number of implants that were available for analysis were extracted from original articles for meta-analyses. Eight (six prospective and two retrospective) studies were included. One-year data were available in seven articles, which included 1,015 (451 tilted) implants. Three articles provided 3- to 5-year data from 302 (164 tilted) implants. No significant difference in weighted mean marginal bone loss was found between the tilted and straight implants in the short and medium terms. Three articles reported the incidence of biomechanic complications. There was not enough information to make a comparison. This meta-analysis failed to support the hypothesis that tilted implants that were splinted for the support of fixed prostheses had more marginal bone loss. Additionally, there was not enough evidence to claim a higher incidence of biomechanic complications in tilted implants. However, due to the nature of the study design of the included articles, caution should be exercised when interpreting the results of this review.

  8. Evaluation of tilted cone-beam CT orbits in the development of a dedicated hybrid mammotomograph

    Energy Technology Data Exchange (ETDEWEB)

    Madhav, P; Crotty, D J; Tornai, M P [Department of Radiology, Duke University Medical Center, Durham, NC 27710 (United States); McKinley, R L [Zumatek Incorporated, Chapel Hill, NC 27519 (United States)], E-mail: priti.madhav@duke.edu

    2009-06-21

    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.

  9. 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.

  10. A tilted and warped inner accretion disc around a spinning black hole: an analytical solution

    Science.gov (United States)

    Chakraborty, Chandrachur; Bhattacharyya, Sudip

    2017-08-01

    Inner accretion disc around a black hole provides a rare, natural probe to understand the fundamental physics of the strong gravity regime. A possible tilt of such a disc, with respect to the black hole spin equator, is important. This is because such a tilt affects the observed spectral and timing properties of the disc X-ray emission via Lense-Thirring precession, which could be used to test the theoretical predictions regarding the strong gravity. Here, we analytically solve the steady, warped accretion disc equation of Scheurer and Feiler, and find an expression of the radial profile of the disc tilt angle. In our exact solution, considering a prograde disc around a slowly spinning black hole, we include the inner part of the disc, which was not done earlier in this formalism. Such a solution is timely, as a tilted inner disc has recently been inferred from X-ray spectral and timing features of the accreting black hole H1743-322. Our tilt angle radial profile expression includes observationally measurable parameters, such as black hole mass and Kerr parameter, and the disc inner edge tilt angle Win, and hence can be ideal to confront observations. Our solution shows that the disc tilt angle in 10-100 gravitational radii is a significant fraction of the disc outer edge tilt angle, even for Win = 0. Moreover, tilt angle radial profiles have humps in ˜10-1000 gravitational radii for some sets of parameter values, which should have implications for observed X-ray features.

  11. 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.

  12. Combined influence of visual scene and body tilt on arm pointing movements: gravity matters!

    Directory of Open Access Journals (Sweden)

    Cécile Scotto Di Cesare

    Full Text Available 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.

  13. 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.

  14. 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.

  15. Acoustic waves in tilted fiber Bragg gratings for sensing applications

    Science.gov (United States)

    Marques, Carlos A. F.; Alberto, Nélia J.; Domingues, Fátima; Leitão, Cátia; Antunes, Paulo; Pinto, João. L.; André, Paulo

    2017-05-01

    Tilted fiber Bragg gratings (TFBGs) are one of the most attractive kind of optical fiber sensor technology due to their intrinsic properties. On the other hand, the acousto-optic effect is an important, fast and accurate mechanism that can be used to change and control several properties of fiber gratings in silica and polymer optical fiber. Several all-optical devices for optical communications and sensing have been successfully designed and constructed using this effect. In this work, we present the recent results regarding the production of optical sensors, through the acousto-optic effect in TFBGs. The cladding and core modes amplitude of a TFBG can be controlled by means of the power levels from acoustic wave source. Also, the cladding modes of a TFBG can be coupled back to the core mode by launching acoustic waves. Induced bands are created on the left side of the original Bragg wavelength due to phase matching to be satisfied. The refractive index (RI) is analyzed in detail when acoustic waves are turned on using saccharose solutions with different RI from 1.33 to 1.43.

  16. A broadband ultrathin metamaterial absorber using tilted parallel strips

    Science.gov (United States)

    Ahmadi, Farzad; Ida, Nathan

    2017-02-01

    A polarization insensitive metamaterial absorber is proposed consisting of a dielectric layer sandwiched between two tilted parallel metallic strips and a ground plane. First, a new analytical model is introduced to predict the resonance frequency for square, rectangular and wire geometries which shows less relative errors in comparison with previously proposed models. Then, ultra wide bandwidth absorption covering the entire x-band and Ku-band restricting a 10-dB absorption bandwidth is achieved with a relative material thickness λ0/10 and a relative FWHM absorption bandwidth of 90% for normal incidence angle. The model also shows good absorption coefficients for oblique incident angles for both s- and p-polarizations. Three different resonance modes are observed, which led to such broadband absorption. Each resonance mode is investigated to determine its dependence on the scatterers and unit cell dimensions, which can help one to design a multiple band absorber. The electromagnetic field distributions of the scatterers are studied to explain the absorber mechanism. The results are compared to previous works showing remarkable improvement.

  17. Compressor Study to Meet Large Civil Tilt Rotor Engine Requirements

    Science.gov (United States)

    Veres, Joseph P.

    2009-01-01

    A vehicle concept study has been made to meet the requirements of the Large Civil Tilt Rotorcraft vehicle mission. A vehicle concept was determined, and a notional turboshaft engine system study was conducted. The engine study defined requirements for the major engine components, including the compressor. The compressor design-point goal was to deliver a pressure ratio of 31:1 at an inlet weight flow of 28.4 lbm/sec. To perform a conceptual design of two potential compressor configurations to meet the design requirement, a mean-line compressor flow analysis and design code were used. The first configuration is an eight-stage axial compressor. Some challenges of the all-axial compressor are the small blade spans of the rear-block stages being 0.28 in., resulting in the last-stage blade tip clearance-to-span ratio of 2.4 percent. The second configuration is a seven-stage axial compressor, with a centrifugal stage having a 0.28-in. impeller-exit blade span. The compressors conceptual designs helped estimate the flow path dimensions, rotor leading and trailing edge blade angles, flow conditions, and velocity triangles for each stage.

  18. View Angle Tilting Echo Planar Imaging for Distortion Correction

    Science.gov (United States)

    Ahn, Sinyeob; Hu, Xiaoping

    2011-01-01

    Geometric distortion caused by field inhomogeneity along the phase-encode (PE) direction is one of the most prominent artifacts due to a relatively low effective bandwidth along that direction in magnetic resonance echo planar imaging (EPI). This work describes a method for correcting in-plane image distortion along the PE direction using a view angle tilting (VAT) imaging technique in spin-echo EPI (SE-EPI). SE-EPI with VAT (SE-EPI-VAT) utilizes the addition of gradient blips along the slice-select (SS) direction, concurrently applied with the PE gradient blips, producing an additional phase. This phase effectively offsets an unwanted phase accumulation caused by field inhomogeneity, resulting in the removal of image distortion along the PE direction. The proposed method is simple and straightforward both in implementation and application with no scan time penalty. Therefore, it is readily applicable on commercial scanners without having any customized post-processing. The efficacy of the SE-EPI-VAT technique in the correction of image distortion is demonstrated in phantom and in vivo brain imaging. PMID:22213567

  19. Planar waveguide tilted Bragg grating refractometer fabricated through physical micromachining and direct UV writing.

    Science.gov (United States)

    Holmes, Christopher; Carpenter, Lewis G; Rogers, Helen L; Sparrow, Ian J G; Gates, James C; Smith, Peter G R

    2011-06-20

    A set of rapid prototyping techniques are combined to construct a laterally-tilted Bragg grating refractometer in a novel planar geometry. The tilted Bragg grating is fabricated in a silica-on-silicon planar substrate using a dual beam direct UV writing (DUW) technique. Lateral cladding mode confinement is subsequently achieved by physically micromachining two trenches either side of the direct UV written waveguide. The resulting device is demonstrated as an effective refractometer, displaying a comparable sensitivity to tilted Bragg gratings in a fiber optical geometry, but with the added advantages of planar integration.

  20. Optimal ADF STEM imaging parameters for tilt-robust image quantification.

    Science.gov (United States)

    MacArthur, K E; D'Alfonso, A J; Ozkaya, D; Allen, L J; Nellist, P D

    2015-09-01

    An approach towards experiment design and optimisation is proposed for achieving improved accuracy of ADF STEM quantification. In particular, improved robustness to small sample mis-tilts can be achieved by optimising detector collection and probe convergence angles. A decrease in cross section is seen for tilted samples due to the reduction in channelling, resulting in a quantification error, if this is not taken into account. At a smaller detector collection angle the increased contribution from elastic scattering, which initially increases with tilt, can be used to offset the decrease in the TDS signal. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Modulation of internal estimates of gravity during and after prolonged roll-tilts.

    Directory of Open Access Journals (Sweden)

    Alexander A Tarnutzer

    Full Text Available Perceived direction of gravity, as assessed by the subjective visual vertical (SVV, shows roll-angle dependent errors that drift over time and a bias upon return to upright. According to Bayesian observer theory, the estimated direction of gravity is derived from the posterior probability distribution by combining sensory input and prior knowledge about earth-vertical in a statistically optimal fashion. Here we aimed to further characterize the stability of SVV during and after prolonged roll-tilts. Specifically we asked whether the post-tilt bias is related to the drift pattern while roll-tilted. Twenty-nine healthy human subjects (23-56 yo repetitively adjusted a luminous arrow to the SVV over periods of 5 min while upright, roll-tilted (± 45°, ± 90°, and immediately after returning to upright. Significant (p<0.05 drifts (median absolute drift-amplitude: 10°/5 min were found in 71% (± 45° and 78% (± 90° of runs. At ± 90° roll-tilt significant increases in absolute adjustment errors were more likely (76%, whereas significant increases (56% and decreases (44% were about equally frequent at ± 45°. When returning to upright, an initial bias towards the previous roll-position followed by significant exponential decay (median time-constant: 71 sec was noted in 47% of all runs (all subjects pooled. No significant correlations were found between the drift pattern during and immediately after prolonged roll-tilt. We conclude that the SVV is not stable during and after prolonged roll-tilt and that the direction and magnitude of drift are individually distinct and roll-angle-dependent. Likely sensory and central adaptation and random-walk processes contribute to drift while roll-tilted. Lack of correlation between the drift and the post-tilt bias suggests that it is not the inaccuracy of the SVV estimate while tilted that determines post-tilt bias, but rather the previous head-roll orientation relative to gravity. We therefore favor central

  2. Does osteoporosis reduce the primary tilting stability of cementless acetabular cups?

    Science.gov (United States)

    von Schulze Pellengahr, Christoph; von Engelhardt, Lars V; Wegener, Bernd; Müller, Peter E; Fottner, Andreas; Weber, Patrick; Ackermann, Ole; Lahner, Matthias; Teske, Wolfram

    2015-04-21

    Cementless hip cups need sufficient primary tilting stability to achieve osseointegration. The aim of the study was to assess differences of the primary implant stability in osteoporotic bone and in bone with normal bone density. To assess the influence of different cup designs, two types of threaded and two types of press-fit cups were tested. The maximum tilting moment for two different cementless threaded cups and two different cementless press-fit cups was determined in macerated human hip acetabuli with reduced (n=20) and normal bone density (n=20), determined using Q-CT. The tilting moments for each cup were determined five times in the group with reduced bone density and five times in the group with normal bone density, and the respective average values were calculated. The mean maximum extrusion force of the threaded cup Zintra was 5670.5 N (max. tilting moment 141.8 Nm) in bone with normal density and.5748.3 N (max. tilting moment 143.7 Nm) in osteoporotic bone. For the Hofer Imhof (HI) threaded cup it was 7681.5 N (192.0 Nm) in bone with normal density and 6828.9 N (max. tilting moment 170.7 Nm) in the group with osteoporotic bone. The mean maximum extrusion force of the macro-textured press-fit cup Metallsockel CL was 3824.6 N (max. tilting moment 95.6 Nm) in bone with normal and 2246.2 N (max. tilting moment 56.2 Nm) in osteoporotic bone. For the Monoblock it was 1303.8 N (max. tilting moment 32.6 Nm) in normal and 1317 N (max. tilting moment 32.9 Nm) in osteoporotic bone. There was no significance. A reduction of the maximum tilting moment in osteoporotic bone of the ESKA press-fit cup Metallsockel CL was noticed. Results on macerated bone specimens showed no statistically significant reduction of the maximum tilting moment in specimens with osteoporotic bone density compared to normal bone, neither for threaded nor for the press-fit cups. With the limitation that the results were obtained using macerated bone, we could not detect any restrictions for

  3. Conceptual design study of 1985 commercial tilt rotor transports. Volume 3. STOL design summary. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sambell, K.W.

    1976-04-01

    A conceptual design study is presented of 1,985 commercial tilt rotor STOL transports for a NASA 200 n. mi. (370 km) STOL Mission. A 100-passenger STOL Variant (Bell D313) of the Phase I VTOL Tilt Rotor Aircraft is defined. Aircraft characteristics are given; with the aircraft redesigned to meet 2,000-foot (610 m) field criteria, with emphasis on low fuel consumption and low direct operating cost. The 100-passenger STOL Tilt Rotor Aircraft was analyzed for performance, weights, economics, handling qualities, noise footprint and aeroelastic stability. (GRA)

  4. Description of multi-quasiparticle bands by the tilted axis cranking model 21.60.-n; High K rotational bands; Tilted axis cranking; Multi-quasiparticle configurations

    CERN Document Server

    Frauendorf, S

    2000-01-01

    The selfconsistent cranking approach is extended to the case of rotation about an axis which is tilted with respect to the principal axes of the deformed potential (Tilted Axis Cranking). Expressions for the energies and the intra bands electro-magnetic transition probabilities are given. The mean field solutions are interpreted in terms of quantal rotational states. The construction of the quasiparticle configurations and the elimination of spurious states is discussed. The application of the theory to high spin data is demonstrated by analyzing the multi-quasiparticle bands in the nuclides with N=102,103 and Z=71,72,73.

  5. Process, Design and Materials for Unidirectionally Tilted Polymeric Micro/Nanohairs and Their Adhesion Characteristics

    Directory of Open Access Journals (Sweden)

    Hyeon Seong Im

    2016-09-01

    Full Text Available Recent research in the field of gecko-inspired dry adhesive has focused on modifying the material and structural properties of polymer-based nanohairs. Polymers such as polystyrene (PS, high-density polyethylene (HDPE, ultraviolet curable epoxy (SU-8, polyurethane acrylate (PUA, polycarbonate (PC, and polydimethyl siloxane (PDMS can fulfill many mechanical property requirements, are easily tunable, and can be produced via large-scale fabrication. However, the fabrication process for tilted structure remains challenging. The tilted structure is a crucial factor in high-degree conformal contact, which facilitates high adhesion, low effective modulus, and directional adhesion properties. Recent studies have attempted to create a tilted structure by applying beam irradiation, mechanical and thermal stress, and magnetic fields. This review provides a comprehensive investigation into advanced strategies for producing tilted polymeric nanostructures and their potential applications in the near future.

  6. Implications of cavity, topographic and geologic influences on tilt and strain observations

    Science.gov (United States)

    Harrison, J. C.

    1978-01-01

    Tilt and strain observations are importantly (pathologically at the 100%, typically at the few 10s% level) affected by cavities, topography, and geological inhomogenities; gravity observation are practically unaffected. The traditional earth tide observatory and abandoned mine or tunnel is a very poor place to measure body tides because of the complicated cavities, topography and geology. Instead, the ideal site for observing the body tide is in flat terrain with horizontally layered, mechanically homogeneous geology. Strain will be measured with long surface- or trench-mounted laser strain meters and tilt with long, surface- or trench mounted liquid levels, or with borehole tiltmeters. Horizontal geological discontinuities can produce large perturbations of the tilt and strain tides, and these perturbations, using the known homogeneous tidal strains and tilts, can be used in exploring local structure in favorable cases and, through possible time variations of tidal admittances, in predicting earthquakes.

  7. Extended long-term (5 years) outcomes of triangle tilt surgery in obstetric brachial plexus injury.

    Science.gov (United States)

    Nath, Rahul K; Somasundaram, Chandra

    2013-01-01

    We evaluated the "extended" long-term (5 years) functional outcomes in obstetric brachial plexus injury (OBPI) patients, who underwent triangle tilt surgery between February 2005 and January 2008. Twenty two children (9 girls and 13 boys, mean age at surgery was 5.8 years; ranging 2.1-11.8 years old), who initially presented with medial rotation contracture and scapula deformity secondary to obstetric brachial plexus injury were included in this study. Functional movements were evaluated pre-operatively, and 5 years following triangle tilt surgery by modified Mallet scale. Here, we report long-term (5 years) follow-up of triangle tilt surgery for 22 OBPI patients. Upper extremity functional movements such as, external rotation (2.5±0.6 to 4.1±0.8, ptriangle tilt surgery improved all shoulder functions significantly, and maintained over the extended long-term (5 years) in these patients.

  8. Tilt meters for the Alignment System of the CMS Experiment: Users Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E.; Ferrando, A.; Josa, M.I.; Molinero, A.; Navarrete, J.; Oller, J.C.; Yuste, C.

    2007-09-27

    We present the instructions for the use of the electrolytic tilt meters installed in the link alignments system of the CMS experimental and give the Data Base to be used as a Handbook during CMS operation. (Author) 16 refs.

  9. High Speed Rail Tilt Train Technology : A State of the Art Survey

    Science.gov (United States)

    1992-06-01

    This report presents an assessment of the technical and operational features of existing and proposed tilt-body rail passenger vehicles. Basic concepts of railroad route selection, track geometry, and curve negotiation are reviewed, and the rationale...

  10. Impact of Mechanical down Tilt and Height on the Pilot Coverage of UMTS Networks

    Directory of Open Access Journals (Sweden)

    N. Faruk

    2012-06-01

    Full Text Available The task of planning a network can be very challenging as it involves many careful studies with a lot of considerations and, at times, trial and error. In this paper, the impacts of antenna mechanical down tilt and antenna height on UMTS network performance are studied. First, we used ASSET3G simulation software to design 3G pilot coverage. Optimization techniques were deployed to study the performance of the network. Simulation results show about 2.6% increase in the coverage area when the antenna height was increased from 15 m to 25 m at the same tilt angle of 0 ° The coverage drops by 24% when transiting from 0° to 6° tilt angle was made for 15 m height antenna. The results also indicated that, pilot pollution could be reduced by choosing optimum down tilt angle.

  11. Correction of broadband albedo measurements affected by unknown slope and sensor tilts

    Science.gov (United States)

    Weiser, Ursula; Olefs, Marc; Schöner, Wolfgang; Weyss, Gernot; Hynek, Bernhard

    2017-02-01

    Geometric effects induced by the underlying terrain slope or by tilt errors of radiation sensors lead to an erroneous measurement of snow or ice albedo. Consequently, diurnal albedo variations are observed. A general method to correct tilt errors of albedo measurements in cases where tilts of both the sensors and the slopes are not accurately measured or known is presented. Atmospheric parameters for this correction method can either be taken from a nearby well-maintained and horizontally levelled measurement of global radiation or alternatively from a solar radiation model. In a next step the model is fitted to the measured data to determine tilts and directions of the sensors and the underlying terrain slope. This then allows to correct the measured albedo, the radiative balance and the energy balance. Depending on the direction of the slope and the sensors a comparison between measured and corrected albedo values reveals obvious over-or underestimations of albedo.

  12. Helical structures of tilted chiral lipid bilayers viewed as cholesteric liquid crystals

    Science.gov (United States)

    Zhong-Can, Ou-Yang; Ji-Xing, Liu

    1990-09-01

    We have derived the tilt and surface shape-equilibrium equations for tilted chiral lipid bilayers (TCLB's) in analogy with cholesteric liquid crystals. On a cylindrical surface the field of tilt directions of TCLB molecules forms a right-handed helix with 45° gradient angle for k2>0 or a left-handed helix with -45° angle for k2cholesteric chiral curvature modulus. In addition, there exists another type of helical structure that looks like twisted strips or helicoids. We also show that on a spherical surface the tilt field has at least two singular points. These results explain the observed succession of transitions from a vesicular dispersion to a phase involving helical structures and then to tubes.

  13. Experimental Results of Network-Assisted Interference Suppression Scheme Using Adaptive Beam-Tilt Switching

    Directory of Open Access Journals (Sweden)

    Tomoki Murakami

    2017-01-01

    Full Text Available This paper introduces a network-assisted interference suppression scheme using beam-tilt switching per frame for wireless local area network systems and its effectiveness in an actual indoor environment. In the proposed scheme, two access points simultaneously transmit to their own desired station by adjusting angle of beam-tilt including transmit power assisted from network server for the improvement of system throughput. In the conventional researches, it is widely known that beam-tilt is effective for ICI suppression in the outdoor scenario. However, the indoor effectiveness of beam-tilt for ICI suppression has not yet been indicated from the experimental evaluation. Thus, this paper indicates the effectiveness of the proposed scheme by analyzing multiple-input multiple-output channel matrices from experimental measurements in an office environment. The experimental results clearly show that the proposed scheme offers higher system throughput than the conventional scheme using just transmit power control.

  14. D-shaped tilted fiber Bragg grating using magnetic fluid for magnetic field sensor

    Science.gov (United States)

    Ying, Yu; Zhang, Rui; Si, Guang-Yuan; Wang, Xin; Qi, Yuan-Wei

    2017-12-01

    In our work, a numerical investigation of a magnetic field sensor based on a D-shaped tilted fiber Bragg grating and magnetic fluid is performed. The sensing probe is constructed by placing the magnetic fluid film on the flat surface of the D-shaped tilted fiber Bragg grating. We investigate the resonance wavelengths of the proposed structure with different tilted angles of grating ranging from 0° to 20°, and analyze the magnetic field sensing characteristics. The simulation results show that the optical fiber sensor exhibits optimal transmission characteristics with a tilted angle of 8°. The wavelength sensitivity of the magnetic field sensor is as high as -0.18nm/Oe in the range of 30Oe-270Oe, and it demonstrates a linearity up to R2= -0.9998. Such sensor has potential applications in determining magnetic sensing field.

  15. Performance of a double tilted-Rowland-spectrometer on Arcus

    Science.gov (United States)

    Günther, Hans M.; Cheimets, P. N.; Heilmann, R. K.; Smith, R. K.

    2017-08-01

    Spectroscopy of soft X-rays is an extremely powerful tool to understand the physics of the hot plasma in the universe but in many cases, such as kinematic properties of stellar emission lines or weak absorption features, we have reached the limits of current instrumentation. Critical-angle transmission (CAT) gratings blaze the dispersed spectra into high orders and also offer a high throughput. We present detailed ray-traces for the Arcus mission, which promises an effective area > 0.5 m2 and resolving power > 2500 in the soft X-rays. The mirror consists of Athena-like silicon pore optics (SPOs) arranged in four petals. Each petal spans an azimuth of about 30 degrees and thus offers a point-spread function that is significantly narrower in one dimension than a full mirror would provide. The four channels are split into two pairs, where each pair has its own optical axis. For each pair, CAT gratings are arranged on a tilted Rowland torus and the two separate tori are positioned to overlap in such a way that the dispersed spectra from both pairs can be imaged onto a common set of CCD detectors, while at the same time keeping the requirement of the spectroscopic focus. Our ray-traces show that a set of 16 CCDs is sufficient to cover both zeroths orders and over 90% of the dispersed signal. We study the impact of misalignment, finite size of components, and spacecraft jitter on the spectral resolution and effective area and prove that the design achieves R > 4000 even in the presence of these non-ideal effects.

  16. Forward dynamics simulation of human body under tilting perturbations

    Science.gov (United States)

    Naderi, D.; Pasha Zanoosi, A. A.; Sadeghi-Mehr, M.

    2012-02-01

    Human body uses different strategies to maintain its stability and these strategies vary from fixed-foot strategies to strategies which foot is moved in order to increase the support base. Tilting movement of foot is one type of the perturbations usually is exposed to human body. In the presence of such perturbations human body must employ appropriate reactions to prevent threats like falling. But it is not clear that how human body maintains its stability by central nervous system (CNS). At present study it is tried that by presenting a musculoskeletal model of human lower extremity with four links, three degrees of freedom (DOF) and eight skeletal muscles, the level of muscle activations causes the maintenance of stability, be investigated. Using forward dynamics solution, leads to a more general problem, rather than inverse dynamics. Hence, forward dynamics solution by forward optimization has been used for solving this highly nonlinear problem. To this end, first the system's equations of motion has been derived using lagrangian dynamics. Eight Hill-type muscles as actuators of the system were modeled. Because determination of muscle forces considering their number is an undetermined problem, optimization of an appropriate goal function should be practiced. For optimization problem, the characteristics of genetic algorithms as a method based on direct search, and the direct collocation method, has been profited. Also by considering requirements of problem, some constraints such as conservation of model stability are entered into optimization procedure. Finally to investigate validation of model, the results from optimization and experimental data are compared and good agreements are obtained.

  17. Velocity dependence of vestibular information for postural control on tilting surfaces

    Science.gov (United States)

    Kluzik, JoAnn; Hlavacka, Frantisek

    2016-01-01

    Vestibular information is known to be important for postural stability on tilting surfaces, but the relative importance of vestibular information across a wide range of surface tilt velocities is less clear. We compared how tilt velocity influences postural orientation and stability in nine subjects with bilateral vestibular loss and nine age-matched, control subjects. Subjects stood on a force platform that tilted 6 deg, toes-up at eight velocities (0.25 to 32 deg/s), with and without vision. Results showed that visual information effectively compensated for lack of vestibular information at all tilt velocities. However, with eyes closed, subjects with vestibular loss were most unstable within a critical tilt velocity range of 2 to 8 deg/s. Subjects with vestibular deficiency lost their balance in more than 90% of trials during the 4 deg/s condition, but never fell during slower tilts (0.25–1 deg/s) and fell only very rarely during faster tilts (16–32 deg/s). At the critical velocity range in which falls occurred, the body center of mass stayed aligned with respect to the surface, onset of ankle dorsiflexion was delayed, and there was delayed or absent gastrocnemius inhibition, suggesting that subjects were attempting to actively align their upper bodies with respect to the moving surface instead of to gravity. Vestibular information may be critical for stability at velocities of 2 to 8 deg/s because postural sway above 2 deg/s may be too fast to elicit stabilizing responses through the graviceptive somatosensory system, and postural sway below 8 deg/s may be too slow for somatosensory-triggered responses or passive stabilization from trunk inertia. PMID:27486101

  18. Impaired tilt perception in Parkinson's disease: a central vestibular integration failure.

    Directory of Open Access Journals (Sweden)

    Giovanni Bertolini

    Full Text Available Impaired balance control is a hallmark symptom in Parkinson's disease (PD. Altered sensory-motor integration contributes to the deficiency. We aimed to determine whether impaired vestibular signal processing added to the disorder. We exposed patients (N = 11; 68±6y and age-matched healthy subjects (hS: N = 19; 65±11y on a motion platform in complete darkness to two consecutive forward tilt movements (12 series; N = 24; overall 288 trials and asked them to indicate which tilt was perceived larger. By combing tilt movements with translations we manipulated vestibular sensory input in order to investigate whether putative impairment resulted from a deficiency of the sensory organs (semicircular canals in 'single-SCC-cue-condition', otoliths in 'single-OT-cue-condition' themselves or to a sensory integration failure ('multi-cue-condition'.Tilt discrimination in the multi-cue-condition was inferior in patients compared to hS (p = 0.02. No significant differences between the two groups were found for both single-cue-conditions. Comparison of multi-cue-condition with a prediction resulting from the combination of both single-cue-conditions by optimal observer theory revealed that patients (p = 0.04, in contrast to hS, failed to efficiently combine SCC and OT information to improve tilt perception.We found that PD patients distinguished forward tilts less precise than hS, suggesting impaired vestibular perception. Tilt discrimination in patients, moreover, did not improve as much as in hS in conditions where both SCC and OT information was available compared to conditions where only SCC or OT cues were activated. The latter provides evidence that tilt misperception in PD most likely results from an integration failure of vestibular signals.

  19. Geomorphic evidence for late Holocene tilting in southern San Mateo County, California

    Science.gov (United States)

    Adam, David P.

    1975-01-01

    Relations between the stream channels and the alluvial deposits along Bradley Creek and the lower part of Butano Creek suggest that the area has been tilted very recently, and localized swampy conditions supply additional supporting evidence. Radiocarbon dates show that some of the valley alluvium along Butano Creek was deposited no more than 750-800 yr ago, and tilting must have Occurred since that time.

  20. Photosensitivity control of an isotropic medium through polarization of light pulses with tilted intensity front.

    Science.gov (United States)

    Kazansky, Peter G; Shimotsuma, Yasuhiko; Sakakura, Masaaki; Beresna, Martynas; Gecevičius, Mindaugas; Svirko, Yuri; Akturk, Selcuk; Qiu, Jianrong; Miura, Kiyotaka; Hirao, Kazuyuki

    2011-10-10

    We present the first experimental evidence of anisotropic photosensitivity of an isotropic homogeneous medium under uniform illumination. Our experiments reveal fundamentally new type of light induced anisotropy originated from the hidden asymmetry of pulsed light beam with a finite tilt of intensity front. We anticipate that the observed phenomenon, which enables employing mutual orientation of a light polarization plane and pulse front tilt to control interaction of matter with ultrashort light pulses, will open new opportunities in material processing.

  1. Patients with severe acquired brain injury show increased arousal in tilt-table training

    DEFF Research Database (Denmark)

    Riberholt, Christian G; Thorlund, Jonas Bloch; Mehlsen, Jesper

    2013-01-01

    Patients with severe acquired brain injury (ABI) are often mobilised using a tilt-table. Complications such as orthostatic intolerance have been reported. The primary objective of this study was to investigate if using a tilt-table was feasible for mobilising patients with severe ABI admitted for...... for sub-acute rehabilitation. We also investigated change in arousal, treatment duration before termination due to orthostatic reactions and change in muscle tone....

  2. Patients with severe acquired brain injury show increased arousal in tilt-table training

    DEFF Research Database (Denmark)

    Riberholt, Christian Gunge; Thorlund, Jonas Bloch; Mehlsen, Jesper

    2013-01-01

    Patients with severe acquired brain injury (ABI) are often mobilised using a tilt-table. Complications such as orthostatic intolerance have been reported. The primary objective of this study was to investigate if using a tilt-table was feasible for mobilising patients with severe ABI admitted...... for sub-acute rehabilitation. We also investigated change in arousal, treatment duration before termination due to orthostatic reactions and change in muscle tone....

  3. Analysis of Free-Space Coupling to Photonic Lanterns in the Presence of Tilt Errors

    Science.gov (United States)

    2017-05-01

    Analysis of Free- Space Coupling to Photonic Lanterns in the Presence of Tilt Errors Timothy M. Yarnall, David J. Geisler, Curt M. Schieler...Massachusetts Avenue Cambridge, MA 02139, USA Abstract—Free space coupling to photonic lanterns is more tolerant to tilt errors and F -number mismatch than...these errors. I. INTRODUCTION Photonic lanterns provide a means for transitioning from the free space regime to the single-mode fiber (SMF) regime by

  4. Motion Perception and Manual Control Performance During Passive Tilt and Translation Following Space Flight

    Science.gov (United States)

    Clement, Gilles; Wood, Scott J.

    2010-01-01

    This joint ESA-NASA study is examining changes in motion perception following Space Shuttle flights and the operational implications of post-flight tilt-translation ambiguity for manual control performance. Vibrotactile feedback of tilt orientation is also being evaluated as a countermeasure to improve performance during a closed-loop nulling task. METHODS. Data has been collected on 5 astronaut subjects during 3 preflight sessions and during the first 8 days after Shuttle landings. Variable radius centrifugation (216 deg/s) combined with body translation (12-22 cm, peak-to-peak) is utilized to elicit roll-tilt perception (equivalent to 20 deg, peak-to-peak). A forward-backward moving sled (24-390 cm, peak-to-peak) with or without chair tilting in pitch is utilized to elicit pitch tilt perception (equivalent to 20 deg, peak-to-peak). These combinations are elicited at 0.15, 0.3, and 0.6 Hz for evaluating the effect of motion frequency on tilt-translation ambiguity. In both devices, a closed-loop nulling task is also performed during pseudorandom motion with and without vibrotactile feedback of tilt. All tests are performed in complete darkness. PRELIMINARY RESULTS. Data collection is currently ongoing. Results to date suggest there is a trend for translation motion perception to be increased at the low and medium frequencies on landing day compared to pre-flight. Manual control performance is improved with vibrotactile feedback. DISCUSSION. The results of this study indicate that post-flight recovery of motion perception and manual control performance is complete within 8 days following short-duration space missions. Vibrotactile feedback of tilt improves manual control performance both before and after flight.

  5. The Effects of Segmentation and Spatial Geometry on the Tilt Illusion

    Directory of Open Access Journals (Sweden)

    Cheng Qiu

    2012-10-01

    Full Text Available In the tilt illusion, when the orientation of the center and surround gratings differ by a small angle, the center grating appears to tilt away from the surround orientation (repulsion; however, for a large difference in angle, the center appears to tilt towards the surround orientation (attraction. Orientation perception therefore depends strongly on the context. Changes in two-dimensional configuration or three-dimensional scene geometry may alter the segmentation features between the center and surround, and cause variations in central orientation perception. We first measured the effect of two sources of segmentation information, contrast, and stereo disparity differences, on the strength of the tilt illusion in human observers. We observed: when the center contrast was high, both low-contrast surround and stereo depth segmentation cues reduced the amplitude of both the repulsion and attraction effect, relative to a high-contrast, 2D surround; a higher surround contrast (70% relative to the center (10% decreased the repulsion effect but increased both the range and magnitude of the attraction effect. Next, we examined the effect of perceptual grouping behind a 3D occluder ring between the center and surround on perceived central orientation. We observed significantly stronger tilt repulsion effects across occlusion than the condition with a ring at the same plane as the center and surround. We also found that the tilt repulsion is selective for the peripheral location of the surround. These results suggest that scene organization plays a role in central orientation perception.

  6. Fast and automatic identification of particle tilt pairs based on Delaunay triangulation.

    Science.gov (United States)

    Vilas, J L; Navas, J; Gómez-Blanco, J; de la Rosa-Trevín, J M; Melero, R; Peschiera, I; Ferlenghi, I; Cuenca, J; Marabini, R; Carazo, J M; Vargas, J; Sorzano, C O S

    2016-12-01

    Random conical tilt (RCT) and orthogonal tilt reconstruction (OTR) are two remarkable methods for reconstructing the three-dimensional structure of macromolecules at low resolution. These techniques use two images at two different sample tilts. One of the most demanding steps in these methods at the image processing level is to identify corresponding particles on both micrographs, and manual or semiautomatic matching methods are usually used. Here we present an approach to solve this bottleneck with a fully automatic method for assigning particle tilt pairs. This new algorithm behaves correctly with a variety of samples, covering the range from small to large macromolecules and from sparse to densely populated fields of view. It is also more rapid than previous approaches. The roots of the method lie in a Delaunay triangulation of the set of independently picked coordinates on both the untilted and tilted micrographs. These triangulations are then used to search an affine transformation between the untilted and tilted triangles. The affine transformation that maximizes the number of correspondences between the two micrographs defines the coordinate matching. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Experimental validation of a technique to measure tilt from a laser guide star.

    Science.gov (United States)

    Belen'kii, M S; Karis, S J; Brown, J M; Fugate, R Q

    1999-05-15

    We have experimentally demonstrated for what is believed to be the first time a method for sensing wave-front tilt with a laser guide star (LGS). The tilt components of wave fronts were measured synchronously from the LGS by use of a telescope with a 0.75-m effective aperture and from the star Polaris by use of a 1.5-m telescope. The Rayleigh guide star was formed at an altitude of 6 km and at a corresponding range of 10.5 km by projection of a focused beam at Polaris from the full aperture at the 1.5-m telescope. Both telescope mounts were unpowered and bolted in place, allowing us to reduce substantially the telescope vibration. The maximum value of the measured cross-correlation coefficient between the tilt for Polaris and the LGS is 0.71. The variations of the measured cross-correlation coefficient in the range from 0.22 to 0.71 are caused by turbulence at altitudes above 6 km, which was not sampled by the laser beacon but affected tilt for Polaris, the cone effect for turbulence below 6 km, residual mount jitter of the telescopes, and variations of the signal/noise ratio. The results support our concept of sensing atmospheric tilt by observing a LGS with an auxiliary telescope and indicate that this method is a possible solution for the tip-tilt problem.

  8. Estimation of pelvic tilt on anteroposterior X-rays - a comparison of six parameters

    Energy Technology Data Exchange (ETDEWEB)

    Tannast, M. [University of Bern, Department of Orthopedic Surgery, Inselspital, Bern (Switzerland); New England Baptist Hospital, Center for Computer Assisted and Reconstructive Surgery, Boston, MA (United States); Tufts University School of Medicine, Boston, MA (United States); Harvard Medical School, Boston, MA (United States); Murphy, S.B. [New England Baptist Hospital, Center for Computer Assisted and Reconstructive Surgery, Boston, MA (United States); Tufts University School of Medicine, Boston, MA (United States); Harvard Medical School, Boston, MA (United States); Langlotz, F. [University of Bern, MEM Research Center for Orthopaedic Surgery, Institute for Surgical Technologies and Biomechanics, Bern (Switzerland); Anderson, S.E. [University of Bern, Department of Diagnostic Interventional and Pediatric Radiology, Bern (Switzerland); Siebenrock, K.A. [University of Bern, Department of Orthopedic Surgery, Inselspital, Bern (Switzerland)

    2006-03-15

    To compare six different parameters described in literature for estimation of pelvic tilt on an anteroposterior pelvic radiograph and to create a simple nomogram for tilt correction of prosthetic cup version in total hip arthroplasty. Simultaneous anteroposterior and lateral pelvic radiographs are taken routinely in our institution and were analyzed prospectively. The different parameters (including three distances and three ratios) were measured and compared to the actual pelvic tilt on the lateral radiograph using simple linear regression analysis. One hundred and four consecutive patients (41 men, 63 women with a mean age of 31.7 years, SD 9.2 years, range 15.7-59.1 years) were studied. The strongest correlation between pelvic tilt and one of the six parameters for both men and women was the distance between the upper border of the symphysis and the sacrococcygeal joint. The correlation coefficient was 0.68 for men (P<0.001) and 0.61 for women (P<0.001). Based on this linear correlation, a nomogram was created that enables fast, tilt-corrected cup version measurements in clinical routine use. This simple method for correcting variations in pelvic tilt on plain radiographs can potentially improve the radiologist's ability to diagnose and interpret malformations of the acetabulum (particularly acetabular retroversion and excessive acetabular overcoverage) and post-operative orientation of the prosthetic acetabulum. (orig.)

  9. Determination of the Optimal Tilt Angle of Solar Collectors for Different Climates of China

    Directory of Open Access Journals (Sweden)

    Haixiang Zang

    2016-07-01

    Full Text Available The tilt angle with the horizon (with respect to the ground of the solar energy system affects the amount of solar radiation received. This paper suggests a simple and universal method to obtain the optimum tilt angles by estimating the monthly mean daily global solar radiation on tilted surfaces facing directly towards the equator, which is based on monthly average daily global solar radiation data produced from Typical Meteorological Year (TMY data. The monthly, seasonal, and yearly optimum tilt angles for photovoltaic panels are calculated at six stations of different climatic types (Tropical Zone (TZ, Subtropical Zone (SZ, Warm Temperate Zone (WTZ, Mid Temperate Zone (MTZ, Cold Temperate Zone (CTZ and Tibetan Plateau Zone (TPZ. The results indicate that changing the monthly, seasonal, and yearly optimum tilt angles causes a significant yearly gain in the solar radiation for the region. In addition, general correlations are generated to estimate the optimum tilt angle of solar collectors at six typical climatic stations of China. The performances of the proposed models are compared using statistical error tests such as the mean absolute bias error (MABE, the root mean square error (RMSE and the correlation coefficients (R.

  10. A novel method of measuring spatial rotation angle using MEMS tilt sensors

    Science.gov (United States)

    Cao, Jian'an; Zhu, Xin; Wu, Hao; Zhang, Leping

    2017-10-01

    This paper presents a novel method of measuring spatial rotation angle with a dual-axis micro-electro-mechanical systems tilt sensor. When the sensor is randomly mounted on the surface of the rotating object, there are three unpredictable and unknown mounting position parameters: α, the sensor’s swing angle on the measuring plane; β, the angle between the rotation axis and the horizontal plane; and γ, the angle between the measuring plane and the rotation axis. Thus, the sensor’s spatial rotation model is established to describe the relationship between the measuring axis, rotation axis, and horizontal plane, and the corresponding analytical equations are derived. Furthermore, to eliminate the deviation caused by the uncertain direction of the rotation axis, an extra perpendicularly mounted, single-axis tilt sensor is combined with the dual-axis tilt sensor, forming a three-axis tilt sensor. Then, by measuring the sensors’ three tilts and solving the model’s equations, the object’s spatial rotation angle is obtained. Finally, experimental results show that the developed tilt sensor is capable of measuring spatial rotation angle in the range of  ±180° with an accuracy of 0.2° if the angle between the rotation axis and the horizontal plane is less than 75°.

  11. Roll tilt psychophysics in rhesus monkeys during vestibular and visual stimulation.

    Science.gov (United States)

    Lewis, Richard F; Haburcakova, Csilla; Merfeld, Daniel M

    2008-07-01

    How does the brain calculate the spatial orientation of the head relative to gravity? Psychophysical measurements are critical to investigate this question, but such measurements have been limited to humans. In non-human primates, behavioral measures have focused on vestibular-mediated eye movements, which do not reflect percepts of head orientation. We have therefore developed a method to measure tilt perception in monkeys, derived from the subjective visual vertical (SVV) task. Two rhesus monkeys were trained to align a light bar parallel to gravity and performed this task during roll tilts, centrifugation, and roll optokinetic stimulation. The monkeys accurately aligned the light bar with gravity during static roll tilts but also demonstrated small orientation-dependent misperceptions of the tilt angle analogous to those measured in humans. When the gravito-inertial force (GIF) rotated dynamically in the roll plane, SVV responses remained closely aligned with the GIF during roll tilt of the head (coplanar canal rotational cues present), lagged slightly behind the GIF during variable-radius centrifugation (no canal cues present), and shifted gradually during fixed-radius centrifugation (orthogonal yaw canal cues present). SVV responses also deviated away from the earth-vertical during roll optokinetic stimulation. These results demonstrate that rotational cues derived from the semicircular canals and visual system have prominent effects on psychophysical measurements of roll tilt in rhesus monkeys and therefore suggest that a central synthesis of graviceptive and rotational cues contributes to percepts of head orientation relative to gravity in non-human primates.

  12. Asymmetrical dual tapered fiber Mach-Zehnder interferometer for fiber-optic directional tilt sensor.

    Science.gov (United States)

    Lee, Cheng-Ling; Shih, Wen-Cheng; Hsu, Jui-Ming; Horng, Jing-Shyang

    2014-10-06

    This work proposes a novel, highly sensitive and directional fiber tilt sensor that is based on an asymmetrical dual tapered fiber Mach-Zehnder interferometer (ADTFMZI). The fiber-optic tilt sensor consists of two abrupt tapers with different tapered waists into which are incorporated a set of iron spheres to generate an asymmetrical strain in the ADTFMZI that is correlated with the tilt angle and the direction of inclination. Owing to the asymmetrical structure of the dual tapers, the proposed sensor can detect the non-horizontal/horizontal state of a structure and whether the test structure is tilted to clockwise or counterclockwise by measuring the spectral responses. Experimental results show that the spectral wavelengths are blue-shifted and red-shifted when the sensor tilts to clockwise (-θ) and counterclockwise ( + θ), respectively. Tilt angle sensitivities of about 335 pm/deg. and 125 pm/deg. are achieved in the -θ and + θ directions, respectively, when the proposed sensing scheme is utilized.

  13. 立位時の血圧調節に及ぼす下腿筋群の収縮作用

    OpenAIRE

    井福, 裕俊; 宮村, 直幸; 坂本, 将基; 齋藤, 和也; 中山, 貴文; イフク, ヒロトシ; ミヤムラ, ナオユキ; サカモト, マサノリ; サトウ, カズヤ; ナカヤマ, タカフミ; Ifuku, Hirotoshi; Miyamura, Naoyuki; Sakamoto, Masanori; Saitoh, Kazuya; Nakayama Takafumi

    2014-01-01

    The purpose of the present study was to compare cardiovascular responses during head-up tilt with more engagement of antigravity muscles in the lower legs with those during normal head-up tilt. Blood pressure, heart rate,stroke volume, cardiac output, cardiac contractility, and pulse wave velocity during both head-up tilts were measured in six male subjects. In head-up tilt with more engagement of antigravity muscles in the lower legs, the diastolicblood pressure was increased significantly, ...

  14. Use of standard and anatomic-tilt lateral X-rays to determine distal radius volar angulation.

    Science.gov (United States)

    Yi, Ju Won; Kim, Rag Gyu; Choi, Jin Ha; Kim, Jae Kwang

    2012-04-01

    To determine the reliability of measurements of distal radius volar tilt using either standard lateral or anatomic tilt lateral (ATL) radiographs, and to compare the mean values obtained using each radiographic method. We obtained standard and 23° ATL plain radiographs of the distal radii of 20 patients with a distal radius fracture treated with a volar locking plate, and of 20 healthy individuals without a history of fracture of the wrist. Three orthopedic surgeons measured volar tilt twice with an interval of 4 weeks. We analyzed intraobserver and interobserver reliability and compared intraobserver means of volar tilts obtained using standard and ATL radiographs. The volar tilts measured using ATL radiographs in patients and healthy controls showed moderate to excellent intraobserver and interobserver reliability, whereas those determined using standard lateral radiographs showed poor to moderate intraobserver and interobserver reliability in patients and controls. However, the mean values of volar tilts measured in standard lateral radiographs and in ATL radiographs were similar in patients and not significantly different in healthy controls. Volar tilt measurements obtained using anatomic tilt lateral radiographs provided moderate to excellent reliability. However, we found no statistically significant difference between volar tilts determined using ATL and standard lateral radiographs. Accordingly, standard lateral and ATL radiographs are interchangeable with respect to volar tilt measurements. Diagnostic II. Copyright © 2012 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  15. Mechanisms of Günther Tulip filter tilting during transfemoral placement.

    Science.gov (United States)

    Matsui, Y; Horikawa, M; Ohta, K; Jahangiri Noudeh, Y; Kaufman, J A; Farsad, K

    The purpose of this study was to characterize the mechanisms of Günther Tulip filter (GTF) tilting during transfemoral placement in an experimental model with further validation in a clinical series. In an experimental study, 120 GTF placements in an inferior vena cava (IVC) model were performed using 6 configurations of pre-deployment filter position. The angle between the pre-deployment filter axis and IVC axis, and the proximity of the constrained filter legs to IVC wall prior to deployment were evaluated. The association of those pre-deployment factors with post-deployment filter tilting was analyzed. The association noted in the experimental study was then evaluated in a retrospective clinical series of 21 patients. In the experimental study, there was a significant association between the pre-deployment angle and post-deployment filter tilting (P<0.0001). With a low pre-deployment angle (≤5°), a significant association was noted between filter tilting and the proximity of the constrained filter legs to the far IVC wall (P=0.001). In a retrospective clinical study, a significant association between the pre-deployment angle and post-deployment filter tilting was also noted with a linear regression model (P=0.026). Significant association of the pre-deployment angle with post-deployment GTF tilting was shown in both the experimental and clinical studies. The experimental study also showed that proximity of filter legs is relevant when pre-deployment angle is small. Addressing these factors may result in a lower incidence of filter tilting. Copyright © 2017 Editions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

  16. The anterior tilt of the acromion: radiographic evaluation and correlation with shoulder diseases

    Energy Technology Data Exchange (ETDEWEB)

    Prato, N.; Peloso, D.; Franconeri, A. [Department of Radiology, San Carlo Hospital, Genoa (Italy); Tegaldo, G. [Dept. of Orthopaedic Surgery, San Carlo Hospital, Genoa (Italy); Ravera, G.B. [Inst. of Medical Statistics and Biometry, University of Genoa (Italy); Silvestri, E.; Derchi, L.E. [Inst. of Radiology, University of Genoa (Italy)

    1998-12-01

    The aim of this study was to test whether the anterior tilt of the acromion can be objectively evaluated on lateral radiographs, and whether there is a relation between this anatomical feature and the most common shoulder diseases. Lateral radiographs of 15 dried scapulas were performed in neutral position and with 5 of caudal, cranial, anterior and posterior angulations. Two hundred and forty-three shoulders, both asymptomatic and affected by chronic and post-traumatic impingement, calcific tendinitis and instability, were examined by conventional radiography. The presence of rotator-cuff tears was investigated by sonography. A method was elaborated to obtain reproducible lateral radiographs and to determine the acromial tilt angle. Inter- and intraobserver and inter- and intraoperator variations in measurements were evaluated. Variations in tube angulation produced changes in tilt-angle values on dried scapulas. The average tilt angle for the chronic impingement and the instability groups were significantly different from the post-traumatic, calcific tendinitis and control groups. Rotator-cuff tears were significantly more frequent in the chronic impingement group and related to a more acute tilt angle. The inter- and intraobserver variability coefficients were 0.95 and 0.98, whereas the inter- and intraoperator variability coefficients were 0.94 and 0.96, respectively. Conventional radiography using fluoroscopy for positioning is a well-reproducible method for the evaluation of acromial tilt. There is a significant difference in tilt-angle values between some groups of subjects examined, but the lack of specificity limits the clinical importance of such measurement. (orig.) With 6 figs., 3 tabs., 34 refs.

  17. [Comparison of tilt and decentration of four different kinds of aspheric intraocular lenses implantation].

    Science.gov (United States)

    Xing, Xiao-jie; Tang, Xin; Song, Hui; Li, Wei-wei

    2010-04-01

    To measure tilt and decentration of four different kinds of aspheric intraocular lenses (IOLs) with Scheimpflug imaging systems after cataract surgery. One hundred and thirty eyes undertaken cataract surgery and IOLs implantation, including four different kinds of aspheric IOLs [1-piece hydrophilic acrylic IOLs (Akreos AO, Bausch & Lomb); 3-piece acrylic IOLs (Tecnis9003, AMO); 1-piece acrylic IOLs (SN60WF, Alcon) and 1-piece hydrophilic acrylic IOLs (920H, Rayner)] and 3-piece acrylic spherical IOLs (AR40e, AMO), were retrospectively reviewed. Tilt and decentration of IOLs were measured using Scheimpflug system (Pentacam, Oculus) and analyzed with Image-pro plus 6.0 software. Except tilt of AR40e group, the vertical and horizontal tilt and decentration for other groups did not differ significantly. The mean IOL tilt in AO, Z9003, IQ, 920H, AR40e was 2.08 degrees, 2.58 degrees, 1.72 degrees, 1.81 degrees, and 3.22 degrees, respectively, which showed statistically significant differences (F = 4.511, P = 0.003). The mean IOL decentration in AO, Z9003, IQ, 920H and AR40e was 0.04, 0.24, 0.25, 0.19 and 0.18 mm, respectively, which showed significant difference in vertical direction (F = 4.162, P = 0.047). The average tilt significantly correlated with amount of decentration in Z9003 IOL (r = -0.517, P = 0.034). In different types of aspheric IOL implanted within the capsule, tilt and decentration in 1-piece and 4-point haptic IOL are less than those in 3-piece and 2-point haptic IOL.

  18. Teste de inclinação (Tilt-test: do necessário ao imprescindível Test de inclinación (Tilt-test: de lo necesario a lo imprescindible Tilt test: from the necessary to the indispensable

    Directory of Open Access Journals (Sweden)

    Paula Gonçalves Macedo

    2011-03-01

    Full Text Available O teste de inclinação (TI é muito utilizado para a investigação de síncopes e pré-síncopes, pois possibilita o diagnóstico de diferentes tipos de disautonomias. A principal causa de síncope é a Síndrome Vasovagal, cujo diagnóstico é o mais frequente entre as indicações de TI. O exame é utilizado há cerca de 20 anos, mas muitos médicos desconhecem a metodologia. São importantes a indicação apropriada, após exclusão de causas cardíacas de síncope, e a orientação do paciente para garantir a tranquilidade e a segurança do teste. Existem controvérsias na literatura sobre a capacidade diagnóstica e a confiabilidade dos resultados. Os estudos com protocolos diversos podem explicar a variabilidade dos resultados. Nesta revisão, são colocadas as indicações e a metodologia recomendadas pelas diretrizes, complicações, limitações e perspectivas desse exame.El test de inclinación (TI es muy utilizado para la investigación de síncopes y presíncopes, pues posibilita el diagnóstico de diferentes tipos de disautonomías. La principal causa de síncope es el Síndrome Vasovagal, cuyo diagnóstico es el más frecuente entre las indicaciones de TI. EL examen es utilizado hace cerca de 20 años, pero muchos médicos desconocen la metodología. Son importantes la indicación apropiada, después de exclusión de causas cardíacas de síncope, y la orientación del paciente para garantizar la tranquilidad y la seguridad del test. Existen controversias en la literatura sobre la capacidad diagnóstica y la confiabilidad de los resultados. Los estudios con protocolos diversos pueden explicar la variabilidad de los resultados. En esta revisión, son colocadas las indicaciones y la metodología recomendadas por las directrices, complicaciones, limitaciones y perspectivas de ese examen.The head-up tilt test (HUTT is widely used for investigation of syncope and presyncope, since it allows diagnosing different types of dysautonomia

  19. Edge detection of magnetic anomalies using analytic signal of tilt angle (ASTA)

    Science.gov (United States)

    Alamdar, K.; Ansari, A. H.; Ghorbani, A.

    2009-04-01

    Magnetic is a commonly used geophysical technique to identify and image potential subsurface targets. Interpretation of magnetic anomalies is a complex process due to the superposition of multiple magnetic sources, presence of geologic and cultural noise and acquisition and positioning error. Both the vertical and horizontal derivatives of potential field data are useful; horizontal derivative, enhance edges whereas vertical derivative narrow the width of anomaly and so locate source bodies more accurately. We can combine vertical and horizontal derivative of magnetic field to achieve analytic signal which is independent to body magnetization direction and maximum value of this lies over edges of body directly. Tilt angle filter is phased-base filter and is defined as angle between vertical derivative and total horizontal derivative. Tilt angle value differ from +90 degree to -90 degree and its zero value lies over body edge. One of disadvantage of this filter is when encountering with deep sources the detected edge is blurred. For overcome this problem many authors introduced new filters such as total horizontal derivative of tilt angle or vertical derivative of tilt angle which Because of using high-order derivative in these filters results may be too noisy. If we combine analytic signal and tilt angle, a new filter termed (ASTA) is produced which its maximum value lies directly over body edge and is easer than tilt angle to delineate body edge and no complicity of tilt angle. In this work new filter has been demonstrated on magnetic data from an area in Sar- Cheshme region in Iran. This area is located in 55 degree longitude and 32 degree latitude and is a copper potential region. The main formation in this area is Andesith and Trachyandezite. Magnetic surveying was employed to separate the boundaries of Andezite and Trachyandezite from adjacent area. In this regard a variety of filters such as analytic signal, tilt angle and ASTA filter have been applied which

  20. Sacro-femoral-pubic angle: a coronal parameter to estimate pelvic tilt.

    Science.gov (United States)

    Blondel, Benjamin; Schwab, Frank; Patel, Ashish; Demakakos, Jason; Moal, Bertrand; Farcy, Jean-Pierre; Lafage, Virginie

    2012-04-01

    Pelvic tilt is an established measure of position which has been tied to sagittal plane spinal deformity. Increased tilt is noted in the setting of the aging spine and sagittal malalignment syndromes such as flatback (compensatory mechanism). However, the femoral heads are often poorly visualized on sagittal films of scoliosis series in adults, limiting the ability to determine pelvic incidence and tilt. There is a need to establish a coronal plane (better visualization) pelvic parameter which correlates closely with pelvic tilt. This is a retrospective review of 71 adult patients (47 females and 24 males) with full-length standing spine radiographs. Visualization of all spinal and pelvic landmarks was available coronally and sagittally (including pelvis and acetabuli). Pelvic tilt was calculated through validated digital analysis software (SpineView(®)). A new parameter, the sacro-femoral-pubic angle (midpoint of S1 endplate to centroid of acetabuli to superior border of the pubic symphysis) was analyzed for correlation (and predictive ability) with sagittal pelvic tilt. The sacro-femoral-pubic angle (SFP angle) was highly correlated to PT, and according to this analysis, pelvic tilt could be estimated by the formula: PT = 75 - (SFP angle). A Pearson's correlation coefficient of 0.74 (p < 0.005) and predictive ability of 76% accuracy was obtained (±7.5°). The correlation and predictive ability was greater for males compared to females (male: r = 0.87 and predictive model = 93%; female: r = 0.67 and predictive model = 67%). The pelvic tilt is an essential measure in the context of radiographic evaluation of spinal deformity and malalignment. Given the routinely excellent visibility of coronal films this study established the SFP as a coronal parameter which can reliably estimate pelvic tilt. The high correlation and predictive ability of the SFP angle should prompt further study and clinical application when lateral radiographs do not permit

  1. Maintaining Low Voiding Solder Die Attach for Power Die While Minimizing Die Tilt

    Energy Technology Data Exchange (ETDEWEB)

    Hamm, Randy; Peterson, Kenneth A.

    2015-10-01

    This paper addresses work to minimize voiding and die tilt in solder attachment of a large power die, measuring 9.0 mm X 6.5 mm X 0.1 mm (0.354” x 0.256” x 0.004”), to a heat spreader. As demands for larger high power die continue, minimizing voiding and die tilt is of interest for improved die functionality, yield, manufacturability, and reliability. High-power die generate considerable heat, which is important to dissipate effectively through control of voiding under high thermal load areas of the die while maintaining a consistent bondline (minimizing die tilt). Voiding was measured using acoustic imaging and die tilt was measured using two different optical measurement systems. 80Au-20Sn solder reflow was achieved using a batch vacuum solder system with optimized fixturing. Minimizing die tilt proved to be the more difficult of the two product requirements to meet. Process development variables included tooling, weight and solder preform thickness.

  2. Optimal ADF STEM imaging parameters for tilt-robust image quantification

    Energy Technology Data Exchange (ETDEWEB)

    MacArthur, K.E., E-mail: katherine.macarthur@materials.ox.ac.uk [Department of Materials, University of Oxford, Parks Road OX1 3PH (United Kingdom); D’Alfonso, A.J. [School of Physics, University of Melbourne, Parkville, Victoria 2010 (Australia); Ozkaya, D. [Johnson Matthey Technology Centre, Blounts Court Road, Sonning Common, Reading RG4 9NH (United Kingdom); Allen, L.J. [School of Physics, University of Melbourne, Parkville, Victoria 2010 (Australia); Nellist, P.D. [Department of Materials, University of Oxford, Parks Road OX1 3PH (United Kingdom)

    2015-09-15

    An approach towards experiment design and optimisation is proposed for achieving improved accuracy of ADF STEM quantification. In particular, improved robustness to small sample mis-tilts can be achieved by optimising detector collection and probe convergence angles. A decrease in cross section is seen for tilted samples due to the reduction in channelling, resulting in a quantification error, if this is not taken into account. At a smaller detector collection angle the increased contribution from elastic scattering, which initially increases with tilt, can be used to offset the decrease in the TDS signal. - Highlights: • Experimental design is proposed for achieving improved accuracy of STEM quantification. • A decrease in cross section is seen for tilted samples due to a reduction in channelling. • This results in a quantification error if not taken into account. • Robustness to small sample tilts can be achieved at smaller detector collection angles. • The origin of this robustness lies in the balance between TDS and elastic scattering.

  3. Spatial Coding of Eye Movements Relative to Perceived Orientations During Roll Tilt with Different Gravitoinertial Loads

    Science.gov (United States)

    Wood, Scott; Clement, Gilles

    2013-01-01

    This purpose of this study was to examine the spatial coding of eye movements during roll tilt relative to perceived orientations while free-floating during the microgravity phase of parabolic flight or during head tilt in normal gravity. Binocular videographic recordings obtained in darkness from six subjects allowed us to quantify the mean deviations in gaze trajectories along both horizontal and vertical coordinates relative to the aircraft and head orientations. Both variability and curvature of gaze trajectories increased during roll tilt compared to the upright position. The saccades were less accurate during parabolic flight compared to measurements obtained in normal gravity. The trajectories of saccades along perceived horizontal orientations tended to deviate in the same direction as the head tilt, while the deviations in gaze trajectories along the perceived vertical orientations deviated in the opposite direction relative to the head tilt. Although subjects were instructed to look off in the distance while performing the eye movements, fixation distance varied with vertical gaze direction independent of whether the saccades were made along perceived aircraft or head orientations. This coupling of horizontal vergence with vertical gaze is in a consistent direction with the vertical slant of the horopter. The increased errors in gaze trajectories along both perceived orientations during microgravity can be attributed to the otolith's role in spatial coding of eye movements.

  4. System for the Automatic Estimation of the Tilt Angle of a Flat Solar Collector

    Directory of Open Access Journals (Sweden)

    Jorge Fonseca-Campos

    2017-08-01

    Full Text Available In this work, a compact system for the automatic estimation of the tilt angle at any location of the world is presented. The system components are one computer, one GPS receiver and one Python program. The tilt angle is calculated through the maximization of the flux of direct radiation incident upon a flat solar collector. An estimation of the adjustments of this angle at different time periods are obtained. This angle is calculated in steps of six minutes during a whole year. Daily, monthly, biannually and yearly averages of this value are obtained. A comparison of the energetic gain when the tilt angle changes at the different time periods is made as well. Because, the algorithm doesn’t receive as an input the solar radiation incident upon a surface at the location of the calculation, a comparison was made between the results obtained and the results reported for the monthly tilt angle of 22 different places. The root mean square error obtained with this comparison was between 1.5 and 9.5 degrees. The monthly tilt angle estimated deviated in average for less than 6.3° with respect to the values reported for the different locations. Finally, the application of a correction factor in the monthly estimated angles is proposed, which might increase the collected energy.

  5. Normal HR with tilt, yet autonomic dysfunction in persons with Down syndrome.

    Science.gov (United States)

    Bunsawat, Kanokwan; Goulopoulou, Styliani; Collier, Scott R; Figueroa, Arturo; Pitetti, Kenneth H; Baynard, Tracy

    2015-02-01

    Persons with Down syndrome (DS) exhibit altered autonomic function at rest and in response to adrenergic stimuli. It is unknown whether a subset of persons with DS that have similar HR responses to a task would have similar responses in HR variability (HRV). This study aimed to compare cardiac autonomic function during upright tilt using HRV analysis in persons with and without DS when persons with and without DS were matched for the change in HR. Persons with (25 ± 2 yr; 30.4 ± 1.9 kg·m, n = 15) and without DS (27 ± 2 yr; 24.7 ± 1.1 kg·m, n = 15) were matched on their HR response to a 5-min tilt at 80°, whereas a subset of persons with DS (28 ± 3 yr; 33.5 ± 2.0 kg·m, n = 11) were not matched for the change in HR. HRV was assessed in both the frequency (natural log transformation (Ln) of low frequency (LF), high frequency (HF), LF/HF ratio, and total power (TP)) and time domains (root mean square of successive differences [RMSSD]). Changes in HR were similar in DS-matched and control but lower in DS-not matched. Tilt effects were observed for LnHF, LNTP, and RMSSD in all groups (P HR response to passive upright tilt in the DS-matched, we still observed reduced sympathetic dominance in response to upright tilt in persons with DS.

  6. Topological Edge States at a Tilt Boundary in Gated Multilayer Graphene

    Science.gov (United States)

    Vaezi, Abolhassan; Liang, Yufeng; Ngai, Darryl H.; Yang, Li; Kim, Eun-Ah

    2013-04-01

    Despite much interest in engineering new topological surface (edge) states using structural defects, such topological surface states have not been observed yet. We show that recently imaged tilt boundaries in gated multilayer graphene should support topologically protected gapless edge states. We approach the problem from two perspectives: the microscopic perspective of a tight-binding model and an ab initio calculation on a bilayer, and the symmetry-protected topological (SPT) state perspective for a general multilayer. Hence, we establish the tilt-boundary edge states as the first concrete example of the edge states of symmetry-protected Z-type SPT, protected by no-valley mixing, electron-number conservation, and time-reversal T symmetries. Further, we discuss possible phase transitions between distinct SPTs upon symmetry changes. Combined with a recently imaged tilt-boundary network, our findings may explain the long-standing puzzle of subgap conductance in gated bilayer graphene. This proposal can be tested through future transport experiments on tilt boundaries. In particular, the tilt boundaries offer an opportunity for the in situ imaging of topological edge transport.

  7. Topological Edge States at a Tilt Boundary in Gated Multilayer Graphene

    Directory of Open Access Journals (Sweden)

    Abolhassan Vaezi

    2013-06-01

    Full Text Available Despite much interest in engineering new topological surface (edge states using structural defects, such topological surface states have not been observed yet. We show that recently imaged tilt boundaries in gated multilayer graphene should support topologically protected gapless edge states. We approach the problem from two perspectives: the microscopic perspective of a tight-binding model and an ab initio calculation on a bilayer, and the symmetry-protected topological (SPT state perspective for a general multilayer. Hence, we establish the tilt-boundary edge states as the first concrete example of the edge states of symmetry-protected Z-type SPT, protected by no-valley mixing, electron-number conservation, and time-reversal T symmetries. Further, we discuss possible phase transitions between distinct SPTs upon symmetry changes. Combined with a recently imaged tilt-boundary network, our findings may explain the long-standing puzzle of subgap conductance in gated bilayer graphene. This proposal can be tested through future transport experiments on tilt boundaries. In particular, the tilt boundaries offer an opportunity for the in situ imaging of topological edge transport.

  8. [Surgical management of monocular torsion and head tilt after macular translocation].

    Science.gov (United States)

    Klainguti, G; Nguyen, C

    2005-03-01

    Macular translocation following 360 degrees retinotomy is a possible surgical treatment of patients with age-related macular degeneration. However, it produces important subjective disturbances with diplopia and head tilt due to cyclodeviation. Complex surgical procedures involving both oblique muscles and two or four recti have been advocated. Four symptomatic patients with macular translocation underwent counter-rotating surgery by very large recession and advancement of both oblique muscles of the affected eye. Preoperative subjective cyclo-deviations varied between 25 degrees and 60 degrees and head tilt ranged between 25 degrees and 45 degrees . Reduction of cyclodeviation ranged between 22 degrees ant 30 degrees in our four patients. Two patients showed residual cyclo-deviations of 3 degrees and 7 degrees with complete recovery of the head tilt. The remaining two patients showed significant subjective improvements and important reductions of head tilt, in spite of a large residual cyclodeviation. No patient exhibited binocular vision. Without jeopardizing the anterior segment blood supply of these elderly patients, a combined surgical procedure on both oblique muscles has shown to be sufficiently effective in reducing subjective cyclodeviation and head tilt in four cases of macular translocation. A complete counter-rotation does not seem to be required to achieve an important improvement of subjective symptoms. This may be due to sensorial adaptation.

  9. Modeling Spatio-Temporal Dynamics of Optimum Tilt Angles for Solar Collectors in Turkey.

    Science.gov (United States)

    Ertekin, Can; Evrendilek, Fatih; Kulcu, Recep

    2008-05-06

    Quantifying spatial and temporal variations in optimal tilt angle of a solar collector relative to a horizontal position assists in maximizing its performance for energy collection depending on changes in time and space. In this study, optimal tilt angles were quantified for solar collectors based on the monthly global and diffuse solar radiation on a horizontal surface across Turkey. The dataset of monthly average daily global solar radiation was obtained from 158 places, and monthly diffuse radiation data were estimated using an empirical model in the related literature. Our results showed that high tilt angles during the autumn (September to November) and winter (December to February) and low tilt angles during the summer (March to August) enabled the solar collector surface to absorb the maximum amount of solar radiation. Monthly optimum tilt angles were estimated devising a sinusoidal function of latitude and day of the year, and their validation resulted in a high R² value of 98.8%, with root mean square error (RMSE) of 2.06o.

  10. Annual Optimum Tilt Angle Prediction of Solar Collector using PSO Estimator

    Science.gov (United States)

    Dixit, T. V.; Yadav, Anamika; pre="Senior Member ">IEEE,

    2017-08-01

    The amount of solar flux falls on solar collector depends on tilt angle and orientation of collector from the surface. By efficiently regulating the tilt and orientation of solar collector unnecessary loss in potential power can be minimized. In general, for north hemisphere, south facing of the collector is considered as optimum orientation. There are several metrological and geographical factors which affect the optimum tilt angle. In this paper, the PSO estimator has been proposed in order to find optimum tilt angle on annual basis. The results of PSO estimators are compared with ANN estimator and satellite (RETScreen software) data. To evaluate the performance of proposed model MBE, RMSE, Error range, percentage annual error as well as direct method of statistical study have been carried out. During annual tilt angle prediction the annual percentage errors of proposed method and RETScreensoftware data are 0.03% and 7.03% respectively with respect to ANN results. Finally, the average percentage error indicates that the proposed estimator gives better prediction as compared to satellite based results for collecting maximum solar flux at surface of solar collector.

  11. Defining Optimal Head-Tilt Position of Resuscitation in Neonates and Young Infants Using Magnetic Resonance Imaging Data

    OpenAIRE

    Utpal S Bhalala; Malvi Hemani; Meehir Shah; Barbara Kim; Brian Gu; Angelo Cruz; Priya Arunachalam; Elli Tian; Christine Yu; Joshua Punnoose; Steven Chen; Christopher Petrillo; Alisa Brown; Karina Munoz; Grant Kitchen

    2016-01-01

    Head-tilt maneuver assists with achieving airway patency during resuscitation. However, the relationship between angle of head-tilt and airway patency has not been defined. Our objective was to define an optimal head-tilt position for airway patency in neonates (age: 0-28 days) and young infants (age: 29 days-4 months). We performed a retrospective study of head and neck magnetic resonance imaging (MRI) of neonates and infants to define the angle of head-tilt for airway patency. We excluded t...

  12. Phase- and tilt-shift determinations by analysis of spectra sidebands for phase-shift interferometers.

    Science.gov (United States)

    Liu, Qian; Wang, Yang; Ji, Fang; He, Jianguo

    2013-11-01

    A spatial frequency domain method is presented to deal with tilt-shift errors and random phase shift in temporal phase-shift interferometry. The proposed method determines tilt shift and phase shift by analyzing positions and phase variances of sidebands in spatial frequency domain. The method is computationally fast for it is noniterative and needs only one 2D Fourier transform for each spatial carrier interferogram. No initial estimations are required and no ambiguous results are generated with the proposed method. Simulations indicate that the proposed method could detect tilt shift and piston phase shift with high accuracy. Results of experiments conducted in the presence of vibration demonstrate that the proposed method could alleviate fluctuations in the retrieved phase map. The method could be applied to interferometers that are uncalibrated or with an unbalanced piezoelectric transducer, besides interferometers in unsteady conditions.

  13. Ambiguous Tilt and Translation Motion Cues in Astronauts after Space Flight

    Science.gov (United States)

    Clement, G.; Harm, D. L.; Rupert, A. H.; Beaton, K. H.; Wood, S. J.

    2008-01-01

    Adaptive changes during space flight in how the brain integrates vestibular cues with visual, proprioceptive, and somatosensory information can lead to impaired movement coordination, vertigo, spatial disorientation, and perceptual illusions following transitions between gravity levels. This joint ESA-NASA pre- and post-flight experiment is designed to examine both the physiological basis and operational implications for disorientation and tilt-translation disturbances in astronauts following short-duration space flights. The first specific aim is to examine the effects of stimulus frequency on adaptive changes in eye movements and motion perception during independent tilt and translation motion profiles. Roll motion is provided by a variable radius centrifuge. Pitch motion is provided by NASA's Tilt-Translation Sled in which the resultant gravitoinertial vector remains aligned with the body longitudinal axis during tilt motion (referred to as the Z-axis gravitoinertial or ZAG paradigm). We hypothesize that the adaptation of otolith-mediated responses to these stimuli will have specific frequency characteristics, being greatest in the mid-frequency range where there is a crossover of tilt and translation. The second specific aim is to employ a closed-loop nulling task in which subjects are tasked to use a joystick to null-out tilt motion disturbances on these two devices. The stimuli consist of random steps or sum-of-sinusoids stimuli, including the ZAG profiles on the Tilt-Translation Sled. We hypothesize that the ability to control tilt orientation will be compromised following space flight, with increased control errors corresponding to changes in self-motion perception. The third specific aim is to evaluate how sensory substitution aids can be used to improve manual control performance. During the closed-loop nulling task on both devices, small tactors placed around the torso vibrate according to the actual body tilt angle relative to gravity. We hypothesize

  14. Crystal tilting in GaN grown by pendoepitaxy method on sapphire substrate

    Science.gov (United States)

    Kim, Ig-Hyeon; Sone, C.; Nam, Ok-Hyun; Park, Yong-Jo; Kim, Taeil

    1999-12-01

    Pendeoepitaxy of GaN on sapphire substrate with SiO2 mask is demonstrated and characterized by transmission electron microscopy and double crystal x-ray diffraction. A continuous layer of GaN with low dislocation density was achieved by this method. Parts of the GaN layer are tilted symmetrically toward [11-20] direction and have two kinds of coalesce and tilt boundaries. Each boundary was formed by a vertical array of piled up dislocations with the Burger's vector of [11-20]. The tilting mechanism in pendeo-epitaxy is discussed in terms of surface interaction between the SiO2 mask and ELO-GaN.

  15. Liquid film dynamics in horizontal and tilted tubes: Dry spots and sliding drops

    Science.gov (United States)

    King, A. A.; Cummings, L. J.; Naire, S.; Jensen, O. E.

    2007-04-01

    Using a model derived from lubrication theory, we consider the evolution of a thin viscous film coating the interior or exterior of a cylindrical tube. The flow is driven by surface tension and gravity and the liquid is assumed to wet the cylinder perfectly. When the tube is horizontal, we use large-time simulations to describe the bifurcation structure of the capillary equilibria appearing at low Bond number. We identify a new film configuration in which an isolated dry patch appears at the top of the tube and demonstrate hysteresis in the transition between rivulets and annular collars as the tube length is varied. For a tube tilted to the vertical, we show how a long initially uniform rivulet can break up first into isolated drops and then annular collars, which subsequently merge. We also show that the speed at which a localized drop moves down the base of a tilted tube is nonmonotonic in tilt angle.

  16. Design and initial characterization of a compact, ultra high vacuum compatible, low frequency, tilt accelerometer

    Energy Technology Data Exchange (ETDEWEB)

    O’Toole, A., E-mail: amandajotoole@gmail.com, E-mail: riccardo.desalvo@gmail.com [Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, 405 Hilgard Ave, Los Angeles, California 90095 (United States); Peña Arellano, F. E. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Rodionov, A. V.; Kim, C. [California Institute of Technology, Pasadena, California 91125 (United States); Shaner, M.; Asadoor, M. [Mayfield Senior School, 500 Bellefontaine Street Pasadena, California 91105 (United States); Sobacchi, E. [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa (Italy); Dergachev, V.; DeSalvo, R., E-mail: amandajotoole@gmail.com, E-mail: riccardo.desalvo@gmail.com [LIGO Laboratory, California Institute of Technology, MS 100-36, Pasadena, California 91125 (United States); Bhawal, A. [Arcadia High School, 180 Campus Drive, Arcadia, California 91007 (United States); Gong, P. [Department of Precision Instrument, Tsinghua University, Beijing 100084 (China); Lottarini, A. [Department of Computer Science, University of Pisa, Largo B. Pontecorvo 3, 56127 Pisa (Italy); Minenkov, Y. [Sezione INFN Tor Vergata, via della Ricerca Scientfica 1, 00133 Roma (Italy); Murphy, C. [School of Physics, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, Western Australia 6009 (Australia)

    2014-07-15

    A compact tilt accelerometer with high sensitivity at low frequency was designed to provide low frequency corrections for the feedback signal of the Advanced Laser Interferometer Gravitational Wave Observatory active seismic attenuation system. It has been developed using a Tungsten Carbide ceramic knife-edge hinge designed to avoid the mechanical 1/f noise believed to be intrinsic in polycrystalline metallic flexures. Design and construction details are presented; prototype data acquisition and control limitations are discussed. The instrument's characterization reported here shows that the hinge is compatible with being metal-hysteresis-free, and therefore also free of the 1/f noise generated by the dislocation Self-Organized Criticality in the metal. A tiltmeter of this kind will be effective to separate the ground tilt component from the signal of horizontal low frequency seismometers, and to correct the ill effects of microseismic tilt in advanced seismic attenuation systems.

  17. Coulomb Interaction Effect in Weyl Fermions with Tilted Energy Dispersion in Two Dimensions

    Science.gov (United States)

    Isobe, Hiroki; Nagaosa, Naoto

    2016-03-01

    Weyl fermions with tilted linear dispersions characterized by several different velocities appear in some systems including the quasi-two-dimensional organic semiconductor α -(BEDT -TTF )2I3 and three-dimensional WTe2 . The Coulomb interaction between electrons modifies the velocities in an essential way in the low-energy limit, where the logarithmic corrections dominate. Taking into account the coupling to both the transverse and longitudinal electromagnetic fields, we derive the renormalization group equations for the velocities of the tilted Weyl fermions in two dimensions, and found that they increase as the energy decreases and eventually hit the speed of light c to result in the Cherenkov radiation. Especially, the system restores the isotropic Weyl cone even when the bare Weyl cone is strongly tilted and the velocity of electrons becomes negative in certain directions.

  18. Collective effects in tilted Weyl cones: Optical conductivity, polarization, and Coulomb interactions reshaping the cone

    Science.gov (United States)

    Detassis, Fabrizio; Fritz, Lars; Grubinskas, Simonas

    2017-11-01

    Recently, the existence of Dirac/Weyl cones in three-dimensional systems has been demonstrated experimentally. While in high-energy physics the isotropy of the Dirac/Weyl cones is guaranteed by relativistic invariance, in condensed-matter systems corrections to this can occur, with one possible type being a tilt. In this paper, we study the effect of tilted Weyl cones in collective effects. We study both the optical conductivity as well as the polarization function. We also investigate the perturbative effect of long-range Coulomb interactions using a renormalization-group calculation. We find that the tilt is perturbatively renormalized towards zero and at low energies the system flows to an effectively untilted theory.

  19. Anisotropic carrier mobility in two-dimensional materials with tilted Dirac cones: theory and application.

    Science.gov (United States)

    Cheng, Ting; Lang, Haifeng; Li, Zhenzhu; Liu, Zhongfan; Liu, Zhirong

    2017-09-13

    We have theoretically investigated the intrinsic carrier mobility in semimetals with tilted Dirac cones under both longitudinal and transverse acoustic phonon scattering. An analytical formula for the carrier mobility was obtained. It shows that tilting significantly reduces the mobility. The theory was then applied to 8B-Pmmn borophene and borophane (fully hydrogenated borophene), both of which have tilted Dirac cones. The predicted carrier mobilities in 8B-Pmmn borophene at room temperature are 14.8 × 105 and 28.4 × 105 cm2 V-1 s-1 along the x and y directions, respectively, both of which are higher than that in graphene. For borophane, despite its superhigh Fermi velocity, the carrier mobility is lower than that in 8B-Pmmn owing to its smaller elastic constant under shear strain.

  20. Monte Carlo modelling of germanium crystals that are tilted and have rounded front edges

    Energy Technology Data Exchange (ETDEWEB)

    Gasparro, Joel [EC-JRC-IRMM, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel (Belgium); Hult, Mikael [EC-JRC-IRMM, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel (Belgium)], E-mail: mikael.hult@ec.europa.eu; Johnston, Peter N. [Applied Physics, Royal Melbourne Institute of Technology, GPO Box 2476V, Melbourne 3001 (Australia); Tagziria, Hamid [EC-JRC-IPSC, Institute for the Protection and the Security of the Citizen, Via E. Fermi 1, I-21020 Ispra (Vatican City State, Holy See,) (Italy)

    2008-09-01

    Gamma-ray detection efficiencies and cascade summing effects in germanium detectors are often calculated using Monte Carlo codes based on a computer model of the detection system. Such a model can never fully replicate reality and it is important to understand how various parameters affect the results. This work concentrates on quantifying two issues, namely (i) the effect of having a Ge-crystal that is tilted inside the cryostat and (ii) the effect of having a model of a Ge-crystal with rounded edges (bulletization). The effect of the tilting is very small (in the order of per mille) when the tilting angles are within a realistic range. The effect of the rounded edges is, however, relatively large (5-10% or higher) particularly for gamma-ray energies below 100 keV.

  1. Triangle tilt and humeral surgery: Meta-analysis of efficacy and functional outcome.

    Science.gov (United States)

    Nath, Rahul K; Somasundaram, Chandra

    2015-01-18

    To systematically review and analyze the overall impact and effectiveness of bony surgical procedures, the triangle tilt and humeral surgery in a comparative manner in permanent obstetric brachial plexus injury (OBPI) patients. We conducted a literature search and identified original full research articles of OBPI patients treated with a secondary bony surgery, particularly addressing the limitation of shoulder abduction and functions. Further, we analyzed and compared the efficacy and the surgical outcomes of 9 humeral surgery papers with 179 patients, and 4 of our secondary bony procedure, the triangle tilt surgical papers with 86 patients. Seven hundred and thirty-one articles were identified, using the search term "brachial plexus" and obstetric or pediatric (246 articles) or neonatal (219 articles) or congenital (188 articles) or "birth palsy" (121 articles). Further, only a few articles were identified using the bony surgery search, osteotomy "brachial plexus" obstetric (35), "humeral osteotomy" and "brachial plexus" (17), and triangle tilt "brachial plexus" (14). Of all, 12 studies reporting pre- and post- operative or improvement in total Mallet functional score were included in this study. Among these, 9 studies reported the humeral surgery and 4 were triangle tilt surgery. We used modified total Mallet functional score in this analysis. Various studies with humeral surgery showed improvement of 1.4, 2.3, 5.0 and 5.6 total Mallet score, whereas the triangle tilt surgery showed improvement of 5.0, 5.5, 6.0 and 6.2. The triangle tilt surgery improves on what was achieved by humeral osteotomy in the management of shoulder function in OBPI patients.

  2. Comparing functional outcome of triangle tilt surgery performed before versus after two years of age.

    Science.gov (United States)

    Nath, Rahul K; Somasundaram, Chandra; Mahmooduddin, Faiz

    2011-03-16

    Many patients each year who are born with obstetric brachial plexus injuries eventually do not achieve complete recovery. As a result of the primary nerve injuries, these patients will often develop bony deformities involving the shoulder joint as a secondary consequence. The triangle tilt surgery has been shown to be an effective procedure to correct these deformities and has been performed on patients ranging in age from less than a year old to adolescence. The purpose of this retrospective study is to compare outcomes of triangle tilt surgery performed on patients before the age of 2 years versus after 2 years of age to determine an optimal age to operate on these children. 36 patients with deformities developed secondarily from the initial obstetric brachial plexus injury in this study were divided into 2 groups. Group 1, those who had undergone triangle tilt surgery at 2 yrs of age (20 patients). Group 1 age range: 9 months to 23 months, average: 18 months. Group 2 age range: 26 months to 9 years, average: 6 years. Significant differences were found between the 2 groups (0-2 yrs vs > 2yrs) in regards to overall changes (pre- to post-op) in Mallet score, external rotation score, hand-to-mouth score, and supination angle. This study demonstrates that triangle tilt surgery had better outcomes on clinical functioning if performed before the age of 2 years, however, improvement in clinical functioning can still be achieved if the triangle tilt surgery is performed after the age of 2 years as well. A possible mechanism to explain this phenomenon is the increased potential for anatomical remodeling if the triangle tilt surgery is performed at a younger age, thereby leading to significant functional improvement.

  3. Spatial Cognitive Performance During Adaptation to Conflicting Tilt-Translation Stimuli as a Sensorimotor Spaceflight Analog

    Science.gov (United States)

    Kayanickupuram, A. J.; Ramos, K. A.; Cordova, M. L.; Wood, S. J.

    2009-01-01

    The need to resolve new patterns of sensory feedback in altered gravitoinertial environments requires cognitive processes to develop appropriate reference frames for spatial orientation awareness. The purpose of this study was to examine deficits in spatial cognitive performance during adaptation to conflicting tilt-translation stimuli. Fourteen subjects were tilted within a lighted enclosure that simultaneously translated at one of 3 frequencies. Tilt and translation motion was synchronized to maintain the resultant gravitoinertial force aligned with the longitudinal body axis, resulting in a mismatch analogous to spaceflight in which the canals and vision signal tilt while the otoliths do not. Changes in performance on different spatial cognitive tasks were compared 1) without motion, 2) with tilt motion alone (pitch at 0.15, 0.3 and 0.6 Hz or roll at 0.3 Hz), and 3) with conflicting tilt-translation motion. The adaptation paradigm was continued for up to 30 min or until the onset of nausea. The order of the adaptation conditions were counter-balanced across 4 different test sessions. There was a significant effect of stimulus frequency on both motion sickness and spatial cognitive performance. Only 3 of 14 were able to complete the full 30 min protocol at 0.15 Hz, while 7 of 14 completed 0.3 Hz and 13 of 14 completed 0.6 Hz. There were no changes in simple visual-spatial cognitive tests, e.g., mental rotation or match-to-sample. There were significant deficits during 0.15 Hz adaptation in both accuracy and reaction time during a spatial reference task in which subjects are asked to identify a match of a 3D reoriented cube assemblage. Our results are consistent with antidotal reports of cognitive impairment that are common during sensorimotor adaptation with G-transitions. We conclude that these cognitive deficits stem from the ambiguity of spatial reference frames for central processing of inertial motion cues.

  4. Proto-CIRCUS tilted-coil tokamak–torsatron hybrid: Design and construction

    Energy Technology Data Exchange (ETDEWEB)

    Clark, A.W.; Doumet, M.; Hammond, K.C. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027 (United States); Kornbluth, Y. [Yeshiva University, New York, NY 10033 (United States); Spong, D.A. [Oak Ridge National Laboratory, Oak Ridge, TN 37830 (United States); Sweeney, R. [Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027 (United States); Volpe, F.A., E-mail: fvolpe@columbia.edu [Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027 (United States)

    2014-11-15

    Highlights: • A tokamak-like device with tilted toroidal field (TF) coils needs less plasma current than a conventional tokamak. • Rotational transform is partly generated by external coils. Device can be considered a tokamak–torsatron hybrid. • We designed and constructed the first device of this type. • Tilted TF coils are interlinked to each other, which helps to reduce aspect ratio of plasma. • This is a six-coil generalization of CNT stellarator, also at Columbia University, which features two interlinked coils. - Abstract: We present the field-line modeling, design, and construction of a prototype circular-coil tokamak–torsatron hybrid called Proto-CIRCUS. The device has a major radius R = 16 cm and minor radius a < 5 cm. The six “toroidal field” coils are planar as in a tokamak, but they are tilted. This, combined with induced or driven plasma current, is expected to generate rotational transform, as seen in field-line tracing and equilibrium calculations. The device is expected to operate at lower plasma current than a tokamak of comparable size and magnetic field, which might have interesting implications for disruptions and steady-state operation. Additionally, the toroidal magnetic ripple is less pronounced than in an equivalent tokamak in which the coils are not tilted. The tilted coils are interlocked, resulting in a relatively low aspect ratio, and can be moved, both radially and in tilt angle, between discharges. This capability will be exploited for detailed comparisons between calculations and field-line mapping measurements. Such comparisons will reveal whether this relatively simple concept can generate the expected rotational transform.

  5. Optimizing pTILT perfusion imaging in the presence of off-resonance frequency.

    Science.gov (United States)

    Ouyang, Cheng; Sutton, Bradley P

    2013-07-01

    To optimize the perfusion measurements and to recover loss of tagging efficiency from the blood flow measurements in the presence of static field inhomogeneity with the pseudo-continuous arterial spin labeling technique of pTILT, which is sensitive to off-resonance effects due to the employment of concatenated radiofrequency (RF) pulses for labeling. Numerical Bloch simulations were performed to explore the labeling responses of concatenated RF pulses (45°, ±45°) in pTILT as a function of off-resonance frequency. A correction method was proposed by curve-fitting the measured blood flow signal to the signal model obtained from the simulations. The performance of the proposed correction method was examined for three healthy subjects on a 3 Tesla magnet after good shimming as well as under a "worst-case" scenario with deliberate mis-shimming. In cases after good shimming, in which the off-resonance frequency was less than 50 Hz, the perfusion measurements by the optimized pTILT sequence were improved by 12.7% compared with the original pTILT. With a "worst-case" mis-shimming and frequency offset by 80 Hz, the blood flow signal was increased by 68.9% and 64.8% for optimized global and localized pTILT, respectively. Addressing the impact of off-resonance frequency on concatenated RF pulses, tagging efficiency can be effectively recovered in pTILT perfusion measurements. This strategy may be extended to other applications of concatenated RF pulses where sensitivity to magnetic field inhomogeneity prevents accurate quantification. Copyright © 2013 Wiley Periodicals, Inc.

  6. CONTRIBUTION OF QUADRATIC RESIDUE DIFFUSERS TO EFFICIENCY OF TILTED PROFILE PARALLEL HIGHWAY NOISE BARRIERS

    Directory of Open Access Journals (Sweden)

    M. R. Monazzam ، P. Nassiri

    2009-10-01

    Full Text Available This paper presents the results of an investigation on the acoustic performance of tilted profile parallel barriers with quadratic residue diffuser (QRD tops and faces. A 2D boundary element method (BEM is used to predict the barrier insertion loss. The results of rigid and with absorptive coverage are also calculated for comparisons. Using QRD on the top surface and faces of all tilted profile parallel barrier models introduced here is found to improve the efficiency of barriers compared with rigid equivalent parallel barrier at the examined receiver positions. Applying a QRD with frequency design of 400 Hz on 5 degrees tilted parallel barrier improves the overall performance of its equivalent rigid barrier by 1.8 dB(A. Increase in the treated surfaces with reactive elements shifts the effective performance toward lower frequencies. It is found that by tilting the barriers from 0 to 10 degrees in parallel set up, the degradation effects in parallel barriers is reduced but the absorption effect of fibrous materials and also diffusivity of the quadratic residue diffuser is reduced significantly. In this case all the designed barriers have better performance with 10 degrees tilting in parallel set up. The most economic traffic noise parallel barrier which produces significantly high performance, is achieved by covering the top surface of the barrier closed to the receiver by just a QRD with frequency design of 400 Hz and tilting angle of 10 degrees. The average A-weighted insertion loss in this barrier is predicted to be 16.3 dB (A.

  7. Effect of VERO pan-tilt motion on the dose distribution.

    Science.gov (United States)

    Prasetio, Heru; Yohannes, Indra; Bert, Christoph

    2017-07-01

    Tumor tracking is an option for intra-fractional motion management in radiotherapy. The VERO gimbal tracking system creates a unique beam geometry and understanding the effect of the gimbal motion in terms of dose distribution is important to assess the dose deviation from the reference conditions. Beam profiles, output factors (OF) and percentage depth doses (PDD) were measured and evaluated to investigate this effect. In order to find regions affected by the pan-tilt motion, synthesized 2D dose distributions were generated. An evaluation of the 2D dose distribution with the reference position was done using dose difference criteria 1%-4%. The OF and point dose at central axis were measured and compared with the reference position. Furthermore, the PDDs were measured using a special monitoring approach to filtering inaccurate points during the acquisition. Beam profiles evaluation showed that the effect of pan-tilt at inline direction was stronger than at the crossline direction. The maximum average deviation of the full width half maximum (FWHM), flatness, symmetry, penumbra left and right were 0.39 ± 0.25 mm, 0.62 ± 0.50%, 0.76 ± 0.59%, 0.22 ± 0.16 mm, and 0.19 ± 0.15 mm respectively. The ÔF and the measured dose average deviation were pan and tilt and pan or tilt position. The PDD average deviations were 0.58 ± 0.26 % and 0.54 ± 0.25 % for pan-or-tilt and pan-and-tilt position respectively. All the results showed that the deviation at pan and tilt position are higher than pan or tilt. The most influences were observed for the penumbra region and the shift of radiation beam path. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  8. Tilt-shift eddy current probe impact on information value of response signal

    Directory of Open Access Journals (Sweden)

    Chudacik Vladimir

    2016-03-01

    Full Text Available This article deals with the possibility for increasing of the informational value of a response signal using tilt-shift eddy current probe. Numerical simulations based on the FEM method using the OPERA 3D software as well as gained experimental results are presented. The simulated cracks are evaluated at the selected eddy current probe tilts and shifts with respect to conductive plate to obtain additional data needed for its evaluation and localization. Obtained simulation results are compared and discussed with the experimental results.

  9. Mapping misorientation and crystallographic tilt in GaN layers via polychromatic microdiffraction

    Science.gov (United States)

    Barabash, R. I.; Ice, G. E.; Liu, W.; Roder, C.; Figge, S.; Einfeldt, S.; Hommel, D.; Katona, T. M.; Speck, J. S.; Denbaars, S. P.; Davis, R. F.

    The spatial distribution of strain, dislocations, and crystallographic orientation in uncoalesced and coalesced GaN layers grown on striped Si or SiC substrates was studied by polychromatic X-ray microdiffraction and high resolution monochromatic X-ray diffraction. Tilt boundaries formed at the column/wing interface depending on the growth conditions and geometry of the striped substrate. The measurements revealed that the free-hanging wings are tilted upward at room temperature. A misorientation between the GaN(0001) and the Si(111) or SiC(0001) surface normal is observed. Distinct structural properties of the pendeo and cantilever epitaxially grown samples are discussed.

  10. Vector mode conversion based on tilted fiber Bragg grating in ring-core fibers

    Science.gov (United States)

    Mi, Yuean; Ren, Guobin; Gao, Yixiao; Li, Haisu; Zhu, Bofeng; Liu, Yu

    2018-03-01

    We propose a vector mode conversion approach based on tilted fiber Bragg grating (TFBG) written in ring-core fiber with effective separation of eigenmodes. The mode coupling properties of TFBG are numerically investigated. It is shown that under the constraint of phase matching, the conversion of high-order vector modes could be achieved at specific wavelengths. Moreover, the polarization of incident light and tilt angle of TFBG play critical roles in mode coupling process. The proposed TFBG provides an efficient method to realize high-order vector mode conversion, and it shows great potential for fibers based OAM beam generation and fiber lasers with vortex beams output.

  11. Quantum capacitance in topological insulators under strain in a tilted magnetic field

    KAUST Repository

    Tahir, M.

    2012-12-06

    Topological insulators exhibit unique properties due to surface states of massless Dirac fermions with conserved time reversal symmetry. We consider the quantum capacitance under strain in an external tilted magnetic field and demonstrate a minimum at the charge neutrality point due to splitting of the zeroth Landau level. We also find beating in the Shubnikov de Haas oscillations due to strain, which originate from the topological helical states. Varying the tilting angle from perpendicular to parallel washes out these oscillations with a strain induced gap at the charge neutrality point. Our results explain recent quantum capacitance and transport experiments.

  12. Performance Improvement of tilting-pad journal bearings by means of controllable lubrication

    DEFF Research Database (Denmark)

    Cerda, Alejandro; Santos, Ilmar

    2012-01-01

    Tilting-Pad Journal Bearings (TPJB) are commonly used on high-performance turbomachinery due to their excellent stability properties at high speed when compared to other designs for oil film bearings. Hence, efforts have been made to improve the accuracy for the available models for these mechani......Tilting-Pad Journal Bearings (TPJB) are commonly used on high-performance turbomachinery due to their excellent stability properties at high speed when compared to other designs for oil film bearings. Hence, efforts have been made to improve the accuracy for the available models...

  13. CFD calculations on the unsteady aerodynamic characteristics of a tilt-rotor in a conversion mode

    Directory of Open Access Journals (Sweden)

    Li Peng

    2015-12-01

    Full Text Available In order to calculate the unsteady aerodynamic characteristics of a tilt-rotor in a conversion mode, a virtual blade model (VBM and an real blade model (RBM are established respectively. A new multi-layer moving-embedded grid technique is proposed to reduce the numerical dissipation of the tilt-rotor wake in a conversion mode. In this method, a grid system generated abound the rotor accounts for rigid blade motions, and a new searching scheme named adaptive inverse map (AIM is established to search corresponding donor elements in the present moving-embedded grid system to translate information among the different computational zones. A dual-time method is employed to fulfill unsteady calculations on the flowfield of the tilt-rotor, and a second-order centered difference scheme considering artificial viscosity is used to calculate the flux. In order to improve the computing efficiency, the single program multiple data (SPMD model parallel acceleration technology is adopted, according to the characteristic of the current grid system. The lift and drag coefficients of an NACA0012 airfoil, the dynamic pressure distributions below a typical rotor plane, and the sectional pressure distributions on a three-bladed Branum–Tung tilt-rotor in hover flight are calculated respectively, and the present VBM and RBM are validated by comparing the calculated results with available experimental data. Then, unsteady aerodynamic forces and flowfields of an XV-15 tilt-rotor in different modes, such as a fixed conversion mode at different tilt angles (15°, 30°, 60° and a whole conversion mode which converses from 0° to 90°, are numerically simulated by the VBM and RBM respectively. By analyses and comparisons on the simulated results of unsteady aerodynamic forces of the tilt-rotor in different modes, some meaningful conclusions about distorted blade-tip vortex distribution and unsteady aerodynamic force variation in a conversion mode are obtained, and these

  14. Application of engineering models to predict wake deflection due to a tilted wind turbine

    DEFF Research Database (Denmark)

    Guntur, Srinivas; Troldborg, Niels; Gaunaa, Mac

    such a mechanism introduces control complications due to changing wind directions. Deflecting the wake in the vertical direction using tilt, on the other hand, overcomes this challenge. In this paper, the feasibility of steering wake is explored in a simple uniform inflow case. This is done by trying to model...... the wake deflection as a function of the yaw/tilt angle and the rotor thrust, initially using the momentum and vortex theories. Thereafter, a relatively more promising empirical model based on a set of actuator disc CFD computations is proposed. Finally, comments are made on the feasibility of wake control...

  15. Application of engineering models to predict wake deflection due to a tilted wind turbine

    DEFF Research Database (Denmark)

    Guntur, Srinivas; Troldborg, Niels; Gaunaa, Mac

    2012-01-01

    such a mechanism introduces control complications due to changing wind directions. Deflecting the wake in the vertical direction using tilt, on the other hand, overcomes this challenge. In this paper, the feasibility of steering wake is explored in a simple uniform inflow case. This is done by trying to model...... the wake deflection as a function of the yaw/tilt angle and the rotor thrust, initially using the momentum and vortex theories. Thereafter, a relatively more promising empirical model based on a set of actuator disc CFD computations is proposed. Finally, comments are made on the feasibility of wake control...

  16. Dynamic Coefficients of a Tilting Pad With Active Lubrication: Comparison Between Theoretical and Experimental Results

    DEFF Research Database (Denmark)

    Cerda Varela, Alejandro Javier; Santos, Ilmar

    2015-01-01

    experimental results from the literature for industrial grade passive tilting pad bearings. This initial validation is followed by a comparison with experimental identification results obtained from a test rig featuring the active bearing design. Good overall agreement is observed in both configurations......This paper deals with the validation of the mathematical model for predicting the equivalent stiffness and damping of an active tilting-pad bearing. The active bearing design includes an injection nozzle in the pad and a hydraulic supply system featuring a servovalve, which enables to modify...

  17. Effects of rotor location, coning, and tilt on critical loads in large wind turbines

    Science.gov (United States)

    Spera, D. A.; Janetzke, D. C.

    1978-01-01

    Several large (1500 kW) horizontal rotor configurations were analyzed to determine the effects on dynamic loads of upwind downwind rotor locations, coned and radial blade positions, and tilted and horizontal rotor axis positions. Loads were calculated for a range of wind velocities at three locations in the structure: (1) the blade shank; (2) the hub shaft; and (3) the yaw drive. Blade axis coning and rotor axis tilt were found to have minor effects on loads. However, locating the rotor upwind of the tower significantly reduced loads at all locations analyzed.

  18. Behavior of the oculomotor neurons discharge during sinusoidal lateral tilt in the rabbit.

    Science.gov (United States)

    Favilla, M; Ghelarducci, B; La Noce, A; Mais, V; Starita, A

    1979-10-15

    The characteristics of the control exerted by macular and ampullar vestibular receptors on oculomotor neurons (OMN) have been investigated by submitting unanesthetized, encéphale isolé rabbits to sinusoidal lateral tilts of varying frequencies (0.013-0.2 Hz). The phase of the response exhibited a progressive shift towards head velocity with increasing frequencies of tilt. The sensitivity of the OMN significantly increased at frequencies above 0.025 Hz, corresponding to peak accelerations suprathreshold for canals related vestibular neurons. The convergent action of macular and ampullar vestibular receptors in the control of vertical eye movements is discussed in relation with stimulus frequency.

  19. Acceleration of computer-generated holograms using tilted wavefront recording plane method.

    Science.gov (United States)

    Arai, Daisuke; Shimobaba, Tomoyoshi; Murano, Koki; Endo, Yutaka; Hirayama, Ryuji; Hiyama, Daisuke; Kakue, Takashi; Ito, Tomoyoshi

    2015-01-26

    Computer Generated Holograms (CGH) are generated on computers; however, a great deal of computational power is required because the quality of the image is proportional to the number of point light sources of a 3D object. The Wavefront Recording Plane (WRP) method is an algorithm that enables reduction of the amount of calculations required. However, the WRP method also has a defect; it is not effective in the case of a 3D object with a deep structure. In this study, we propose two improved WRP methods: "Least Square Tilted WRP method" and "RANSAC Multi-Tilted WRP method."

  20. Improvement of image quality of holographic projection on tilted plane using iterative algorithm

    Science.gov (United States)

    Pang, Hui; Cao, Axiu; Wang, Jiazhou; Zhang, Man; Deng, Qiling

    2017-12-01

    Holographic image projection on tilted plane has an important application prospect. In this paper, we propose a method to compute the phase-only hologram that can reconstruct a clear image on tilted plane. By adding a constant phase to the target image of the inclined plane, the corresponding light field distribution on the plane that is parallel to the hologram plane is derived through the titled diffraction calculation. Then the phase distribution of the hologram is obtained by the iterative algorithm with amplitude and phase constrain. Simulation and optical experiment are performed to show the effectiveness of the proposed method.

  1. DIPSI: measure of the tip-tilt with a diffraction image phase sensing instrument

    Science.gov (United States)

    Chueca, Sergio; Reyes, Marcos; Schumacher, Achim; Montoya, Luzma

    2008-07-01

    Large segmented mirrors require efficient co-phasing techniques in order to avoid the image degradation due to segments misalignment. DIPSI (Diffraction Image Phase Sensing Instrument) is an instrument developed by IAC, GRANTECAN and LAM. This instrument is being integrated in the Active Phasing Experiment (APE), aimed at testing different phasing techniques for an Extremely Large Telescope. This paper describes the mathematical solution for determining piston and tip-tilt simultaneously from the DIPSI images. A complete set of simulations is included to study the residual errors. Residual errors are bigger when piston and tip-tilt are combined (three degrees of freedom).

  2. Modeling of magnetization precession in spin-torque nano-oscillators with a tilted polarizer

    Directory of Open Access Journals (Sweden)

    Gang Lv

    2015-07-01

    Full Text Available The spin-torque induced magnetization precession dynamics are studied in a spin-valve with a tilted spin polarizer. Macrospin simulations demonstrate that the frequency of precession state depends both on the external DC current and the intrinsic parameters of devices such as the tilted angle of spin polarizer, the damping factor and saturation magnetization of the free layer. The dependence role of those parameters is characterized by phase diagrams. An analytical model is presented, which can successfully interpret the features of precession frequency.

  3. Majorana ϕ0-junction in a disordered spin-orbit coupling nanowire with tilted magnetic field

    Science.gov (United States)

    Huang, Hong; Liang, Qi-Feng; Yao, Dao-Xin; Wang, Zhi

    2017-12-01

    Majorana Josephson junctions in nanowire systems exhibit a pseudo-4π period current-phase relation in the clean limit. In this work, we study how this current-phase relation responds to a tilted magnetic field in a disordered Majorana Josephson junction within the Bogoliubov-de Gennes approach. We show that the tilted magnetic field induces a ϕ0 phase shift to the current-phase relation. Most importantly, we find that this ϕ0-junction behavior is robust even in the presence of disorders.

  4. First-principles study of a tilt grain boundary in rutile

    Science.gov (United States)

    Dawson, I.; Bristowe, P. D.; Lee, M.-H.; Payne, M. C.; Segall, M. D.; White, J. A.

    1996-11-01

    The atomic and electronic structure of a tilt grain boundary in rutile TiO2 has been calculated in an ab initio manner. The method employs a plane-wave basis set and optimized pseudopotentials and is carried out within the local-density approximation of density-functional theory. The study focuses on the structure and energy of the ∑=15 36.9° (210)[001] tilt boundary, which is relaxed to equilibrium using a conjugate gradients iterative minimization technique. The calculations confirm the stability of a proposed atomic model for the boundary and provide some insight into its electronic structure.

  5. Tilt of IOLs and change of axial length in patients of posterior capsular opacification after Nd:YAG laser capsulotomy

    Directory of Open Access Journals (Sweden)

    Chao Gao

    2017-08-01

    Full Text Available AIM: To study the tilt of the intraocular lens(IOLafter Nd:YAG capsulotomy(YAGand variation of the axial length(ALin patients with posterior capsular opacification(PCO.METHODS: The study involved 18 eyes of 14 patients with PCO after uncomplicated phacoemulsification surgery and IOL implantation. All patients had taken examinations, including testing best corrected visual acuity(BCVAby using standard logarithmic visual acuity chart, images of ocular anterior segment and AL by OCT. After the examinations, YAG was operated upon all patients. Each eye received one drop of Diclofenac Sodium Eye Drops immediately after YAG, and patients had taken examinations listed above again. One week later, BCVA and OCT were tested as well. Data(BCVA, tilt of IOLs, and ALwere recorded and analyzed statistically by SPSS.RESULTS: Mean patient age was 73.93±6.94y, including 5 males and 9 females, 8 left eyes and 10 right eyes, altogether 14 patients with 18 eyes. In this study, tilt of IOLs was defined as the angle of anterior surface of IOL and pupil plane(briefly called Tilt, unit:°. Before YAG, mean Tilt was 2.896±2.286°, mean AL was 23.56±0.55mm. 1h after YAG, mean Tilt was 4.702±2.991°, mean AL was 23.40±0.59mm, and BCVA enhanced 3.72±1.74 lines. 1wk after YAG, 9 patients with 12 eyes were involved in the study. The mean Tilt of these 12 eyes was 3.175±1.791° 1h after YAG and 3.434±1.835° 1wk after YAG. There were significant differences between Tilt before YAG and Tilt 1h after YAG. There were no significant differences between AL before YAG and AL 1h after YAG. There were no significant differences between Tilt 1h after YAG and Tilt 1wk after YAG. The lines of enhancement of BCVA 1h after YAG was correlated to differences between Tilt before YAG and Tilt 1h after YAG, of which the correlation coefficient was -0.523.CONCLUSION: IOLs of patients with PCO tilted after YAG, while AL rarely changed. After YAG, the less IOLs tilted, the more BCVA

  6. HEADS UP : Sensorimotor control of the head-neck system

    NARCIS (Netherlands)

    Forbes, P.A.

    2014-01-01

    Head-neck stabilization is inherently challenging even when stationary, requiring constant vigilance to counter the downward pull of gravity. It involves a highly complex biomechanical system comprised of a large mass (the head) balanced on top of seven vertebrae (the neck), that are in turn

  7. Research on Heads Up and Helmet Mounted Symbology

    Science.gov (United States)

    2000-03-30

    examined the difference in the use ofHUDs versus HDDs across different visibility levels. As pilots carne in for an approach to land under different...or the bottom right comer . If the cue appeared on the runway it filled either the top left or the top right box. The results showed that subjects...this case, observers respond to dots of the carne colour more slowly, on average by about 30 ms. The meaning of this reversal is unclear. Discussion

  8. Study and Development of an Integrated Head-Up Display.

    Science.gov (United States)

    1981-06-01

    11 III. WATER PROCESSING AND TESTING...................................... 23 1. Background...Board Fab. details 03608841 Power Strobe Schematic D3608843 Power Strobe Stitch Weld Details 03619030 Power Supplu , high-voltage, 0 & M drawing. D3619010

  9. Heads Up! a Calculation- & Jargon-Free Approach to Statistics

    Science.gov (United States)

    Giese, Alan R.

    2012-01-01

    Evaluating the strength of evidence in noisy data is a critical step in scientific thinking that typically relies on statistics. Students without statistical training will benefit from heuristic models that highlight the logic of statistical analysis. The likelihood associated with various coin-tossing outcomes gives students such a model. There…

  10. Interferometric Water Level Tilt Meter Development in Finland and Comparison with Combined Earth Tide and Ocean Loading Models

    Science.gov (United States)

    Ruotsalainen, Hannu

    2017-05-01

    A modern third-generation interferometric water level tilt meter was developed at the Finnish Geodetic Institute in 2000. The tilt meter has absolute scale and can do high-precision tilt measurements on earth tides, ocean tide loading and atmospheric loading. Additionally, it can be applied in various kinds of geodynamic and geophysical research. The principles and results of the historical 100-year-old Michelson-Gale tilt meter, as well as the development of interferometric water tube tilt meters of the Finnish Geodetic Institute, Finland, are reviewed. Modern Earth tide model tilt combined with Schwiderski ocean tide loading model explains the uncertainty in historical tilt observations by Michelson and Gale. Earth tide tilt observations in Lohja2 geodynamic station, southern Finland, are compared with the combined model earth tide and four ocean tide loading models. The observed diurnal and semidiurnal harmonic constituents do not fit well with combined models. The reason could be a result of the improper harmonic modelling of the Baltic Sea tides in those models.

  11. Effect of compression paddle tilt correction on volumetric breast density estimation

    NARCIS (Netherlands)

    Kallenberg, M.G.J.; Gils, C.H. van; Lokate, M.; Heeten, G.J. den; Karssemeijer, N.

    2012-01-01

    For the acquisition of a mammogram, a breast is compressed between a compression paddle and a support table. When compression is applied with a flexible compression paddle, the upper plate may be tilted, which results in variation in breast thickness from the chest wall to the breast margin. Paddle

  12. TEM10 homodyne detection as an optimal small-displacement and tilt-measurement scheme

    DEFF Research Database (Denmark)

    Delaubert, Vincent; Treps, Nikolas; Lassen, Mikael Østergaard

    2006-01-01

    We report an experimental demonstration of optimal measurements of small displacement and tilt of a Gaussian beam - two conjugate variables - involving a homodyne detection with a TEM10 local oscillator. We verify that the standard split detection is only 64% efficient. We also show a displacemen...... measurement beyond the quantum noise limit, using a squeezed vacuum TEM10 mode within the input beam....

  13. Human cutaneous vascular responses to whole-body tilting, Gz centrifugation, and LBNP

    Science.gov (United States)

    Watenpaugh, Donald E.; Breit, Gregory A.; Buckley, Theresa M.; Ballard, Richard E.; Murthy, Gita; Hargens, Alan R.

    2004-01-01

    We hypothesized that gravitational stimuli elicit cardiovascular responses in the following order with gravitational stress equalized at the level of the feet, from lowest to highest response: short-(SAC) and long-arm centrifugation (LAC), tilt, and lower body negative pressure (LBNP). Up to 15 healthy subjects underwent graded application of the four stimuli. Laser-Doppler flowmetry measured regional skin blood flow. At 0.6 G(z) (60 mmHg LBNP), tilt and LBNP similarly reduced leg skin blood flow to approximately 36% of supine baseline levels. Flow increased back toward baseline levels at 80-100 mmHg LBNP yet remained stable during 0.8-1.0 G(z) tilt. Centrifugation usually produced less leg vasoconstriction than tilt or LBNP. Surprisingly, SAC and LAC did not differ significantly. Thigh responses were less definitive than leg responses. No gravitational vasoconstriction occurred in the neck. All conditions except SAC increased heart rate, according to our hypothesized order. LBNP may be a more effective and practical means of simulating cardiovascular effects of gravity than centrifugation.

  14. Spectral Tilt Change in Stop Consonant Perception by Listeners with Hearing Impairment

    Science.gov (United States)

    Alexander, Joshua M.; Kluender, Keith R.

    2009-01-01

    Purpose: To evaluate how perceptual importance of spectral tilt is altered when formant information is degraded by sensorineural hearing loss. Method: Eighteen listeners with mild to moderate hearing impairment (HI listeners) and 20-23 listeners with normal hearing (NH listeners) identified synthesized stimuli that varied in second formant…

  15. Diagram categories for Uq-tilting modules at roots of unity

    DEFF Research Database (Denmark)

    Andersen, Henning Haahr; Tubbenhauer, Daniel

    In this paper we give a diagrammatic category (inspired by Elias' dihedral cathedral) that is a diagrammatic presentation of the category of Uq(sl2)-tilting modules T for q being an l-th root of unity. Moreover, we, following an approach of Soergel and Stroppel, introduce a grading turning T...

  16. Combining periodic hydraulic tests and surface tilt measurements to explore in situ fracture hydromechanics

    Science.gov (United States)

    Schuite, Jonathan; Longuevergne, Laurent; Bour, Olivier; Guihéneuf, Nicolas; Becker, Matthew W.; Cole, Matthew; Burbey, Thomas J.; Lavenant, Nicolas; Boudin, Frédéric

    2017-08-01

    Fractured bedrock reservoirs are of socio-economical importance, as they may be used for storage or retrieval of fluids and energy. In particular, the hydromechanical behavior of fractures needs to be understood as it has implications on flow and governs stability issues (e.g., microseismicity). Laboratory, numerical, or field experiments have brought considerable insights to this topic. Nevertheless, in situ hydromechanical experiments are relatively uncommon, mainly because of technical and instrumental limitations. Here we present the early stage development and validation of a novel approach aiming at capturing the integrated hydromechanical behavior of natural fractures. It combines the use of surface tiltmeters to monitor the deformation associated with the periodic pressurization of fractures at depth in crystalline rocks. Periodic injection and withdrawal advantageously avoids mobilizing or extracting significant amounts of fluid, and it hinders any risk of reservoir failure. The oscillatory perturbation is intended to (1) facilitate the recognition of its signature in tilt measurements and (2) vary the hydraulic penetration depth in order to sample different volumes of the fractured bedrock around the inlet and thereby assess scale effects typical of fractured systems. By stacking tilt signals, we managed to recover small tilt amplitudes associated with pressure-derived fracture deformation. Therewith, we distinguish differences in mechanical properties between the three tested fractures, but we show that tilt amplitudes are weakly dependent on pressure penetration depth. Using an elastic model, we obtain fracture stiffness estimates that are consistent with published data. Our results should encourage further improvement of the method.

  17. Hydraulic design of a tilting weir allowing for periodic fish migration

    NARCIS (Netherlands)

    Hoitink, A.J.F.; Dommerholt, A.; Gerven, van L.P.A.

    2008-01-01

    The hydraulic design of a tilting weir is presented, which allows for periodic exchange of potadromous fish between freshwater ecosystems. The application domain includes inland waters that need to be isolated hydraulically, preserving the existing ecological connection with the surrounding areas as

  18. Capillary force on a tilted cylinder: Atomic Force Microscope (AFM) measurements.

    Science.gov (United States)

    Kosgodagan Acharige, Sébastien; Laurent, Justine; Steinberger, Audrey

    2017-11-01

    The capillary force in situations where the liquid meniscus is asymmetric, such as the one around a tilted object, has been hitherto barely investigated even though these situations are very common in practice. In particular, the capillary force exerted on a tilted object may depend on the dipping angle i. We investigate experimentally the capillary force that applies on a tilted cylinder as a function of its dipping angle i, using a home-built tilting Atomic Force Microscope (AFM) with custom made probes. A micrometric-size rod is glued at the end of an AFM cantilever of known stiffness, whose deflection is measured when the cylindrical probe is dipped in and retracted from reference liquids. We show that a torque correction is necessary to understand the measured deflection. We give the explicit expression of this correction as a function of the probes' geometrical parameters, so that its magnitude can be readily evaluated. The results are compatible with a vertical capillary force varying as 1/cosi, in agreement with a recent theoretical prediction. Finally, we discuss the accuracy of the method for measuring the surface tension times the cosine of the contact angle of the liquid on the probe. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Tilted Bianchi type I dust fluid cosmological model in general relativity

    Indian Academy of Sciences (India)

    Abstract. 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. A. Bn between metric potentials. The physical and geometrical aspects of the model together with singularity in the model are ...

  20. Demonstration of the Tilting of the Gas-Water Interface under Hydrodynamic Conditions.

    Science.gov (United States)

    Gretener, P. E.

    1979-01-01

    Describes the construction of an apparatus to demonstrate the tilting of an oil-water, gas-water, or gas-oil interface when the subsurface reservoir is under hydrodynamic conditions (i.e., when conditions of lateral flow exist). The model can be constructed of readily-available materials. (RE)

  1. A transversely isotropic medium with a tilted symmetry axis normal to the reflector

    KAUST Repository

    Alkhalifah, Tariq Ali

    2010-05-01

    The computational tools for imaging in transversely isotropic media with tilted axes of symmetry (TTI) are complex and in most cases do not have an explicit closed-form representation. Developing such tools for a TTI medium with tilt constrained to be normal to the reflector dip (DTI) reduces their complexity and allows for closed-form representations. The homogeneous-case zero-offset migration in such a medium can be performed using an isotropic operator scaled by the velocity of the medium in the tilt direction. For the nonzero-offset case, the reflection angle is always equal to the incidence angle, and thus, the velocities for the source and receiver waves at the reflection point are equal and explicitly dependent on the reflection angle. This fact allows for the development of explicit representations for angle decomposition as well as moveout formulas for analysis of extended images obtained by wave-equation migration. Although setting the tilt normal to the reflector dip may not be valid everywhere (i.e., on salt flanks), it can be used in the process of velocity model building, in which such constrains are useful and typically are used. © 2010 Society of Exploration Geophysicists.

  2. An iterative fast sweeping based eikonal solver for tilted orthorhombic media

    KAUST Repository

    Waheed, Umair bin

    2014-08-01

    Computing first-arrival traveltimes of quasi-P waves in the presence of anisotropy is important for high-end near-surface modeling, microseismic-source localization, and fractured-reservoir characterization, and requires solving an anisotropic eikonal equation. Anisotropy deviating from elliptical anisotropy introduces higher-order nonlinearity into the eikonal equation, which makes solving the eikonal equation a challenge. 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 of the higher order nonlinear terms. We use Aitken extrapolation to speed up the convergence rate of the iterative algorithm. The result is an algorithm for first-arrival traveltime computations in tilted anisotropic media. We demonstrate our method on tilted transversely isotropic media and tilted orthorhombic media. Our numerical tests demonstrate that the proposed method can match the first arrivals obtained by wavefield extrapolation, even for strong anisotropy and complex structures. Therefore, for the cases where oneor two-point ray tracing fails, our method may be a potential substitute for computing traveltimes. Our approach can be extended to anisotropic media with lower symmetries, such as monoclinic or even triclinic media.

  3. Shape evolution in 76, 78Kr nuclei at high spins in tilted axis ...

    Indian Academy of Sciences (India)

    A two-dimensional tilted axis cranking Hartree–Fock–Bogoliubov (CHFB) calculation is performed for 76Kr and 78Kr nuclei up to high spins = 30 employing a pairing-plus-quadrupole (PPQ) model interaction Hamiltonian. Intricate details of the evolution of single particle structures and shapes as a function of spin have ...

  4. Marker-free image registration of electron tomography tilt-series

    Directory of Open Access Journals (Sweden)

    Bilbao-Castro JR

    2009-04-01

    Full Text Available Abstract Background Tilt series are commonly used in electron tomography as a means of collecting three-dimensional information from two-dimensional projections. A common problem encountered is the projection alignment prior to 3D reconstruction. Current alignment techniques usually employ gold particles or image derived markers to correctly align the images. When these markers are not present, correlation between adjacent views is used to align them. However, sequential pairwise correlation is prone to bias and the resulting alignment is not always optimal. Results In this paper we introduce an algorithm to find regions of the tilt series which can be tracked within a subseries of the tilt series. These regions act as landmarks allowing the determination of the alignment parameters. We show our results with synthetic data as well as experimental cryo electron tomography. Conclusion Our algorithm is able to correctly align a single-tilt tomographic series without the help of fiducial markers thanks to the detection of thousands of small image patches that can be tracked over a short number of images in the series.

  5. Low-Complexity User Scheduling with Switched Tilting for 3D Cellular Systems

    Directory of Open Access Journals (Sweden)

    Haijing Liu

    2015-01-01

    Full Text Available We propose a low-complexity user scheduling scheme to enhance the sum rate performance for a multicell downlink system, in which the base station (BS is equipped with a large-scale active antenna array. First, we divide each cell into N regions according to the vertical beamwidth of the BS antennas. Next, candidate user equipment (UE items are assigned to corresponding groups to their locations. Each scheduling slot is also divided into N equal-time subslots. Then, at each subslot, we focus on one UE group, select the optimal number, K*, of UEs for simultaneous data transmission in the manner of round-robin scheduling, and adjust the BS antenna tilting to the optimal angle θtilt*. In particular, K* and θtilt* for each UE group are both obtained by means of large-system asymptotic analysis. Benefiting from the random matrix theory tools, the asymptotic analytical results are independent of instantaneous channel state information of UE, which make it possible to solve K* and θtilt* offline, therefore saving the online computational resources significantly. Numerical results verify that the proposed scheme achieves good sum rate performance with extremely low computational complexity.

  6. Interpretation of a discontinuity in the sense of verticality at large body tilt.

    NARCIS (Netherlands)

    Kaptein, R.G.; Gisbergen, J.A.M. van

    2004-01-01

    Results of earlier spatial-orientation studies focusing on the sense of verticality have emphasized an intriguing paradox. Despite evidence that nearly veridical signals for gravicentric head orientation and egocentric visual stimulus orientation are available, roll-tilted subjects err in the

  7. Sublingual nitroglycerin used in routine tilt testing provokes a cardiac output-mediated vasovagal response

    NARCIS (Netherlands)

    Gisolf, J.; Westerhof, B.E.; Dijk, N. van; Wesseling, K.H.; Wieling, W.; Karemaker, J.M.

    2004-01-01

    Objectives We set out to determine the effect of sublingual nitroglycerin (NTG), as used during routine tilt testing in patients with unexplained syncope, on hemodynamic characteristics and baroreflex control of heart rate (HR) and systemic vascular resistance (SVR). Background Nitroglycerin is used

  8. Leedu nõuab Eestilt ja Lätilt tuumaõnnetuse puhuks tagatist / Andrus Karnau

    Index Scriptorium Estoniae

    Karnau, Andrus

    2007-01-01

    Erimeelsustest Ignalina uue tuumajaama partnerite vahel. Leedu nõuab Eestilt ja Lätilt osalemist tuumajäätmete matmisel ja võimalike õnnetuste tagajärgede likvideerimisel, Poola soovib Ignalina uues reaktoris Balti riikidega võrdset osalust. Lisa: Ignalina uus reaktor

  9. Elastic deflection and tilting effect in a multi-stage micro bulk former

    DEFF Research Database (Denmark)

    Mahshid, R.; Hansen, H. N.

    2015-01-01

    the analysis focuses on quantifying the effect the forming force has on the elastic deflection of the machine and the tools by examining the displacement of the moving plate under loaded and unloaded conditions. The results of the measurements were used to describe the tilting effect due to the off...

  10. Open Educational Resources for Call Teacher Education: The iTILT Interactive Whiteboard Project

    Science.gov (United States)

    Whyte, Shona; Schmid, Euline Cutrim; van Hazebrouck Thompson, Sanderin; Oberhofer, Margret

    2014-01-01

    This paper discusses challenges and opportunities arising during the development of open educational resources (OERs) to support communicative language teaching (CLT) with interactive whiteboards (IWBs). iTILT (interactive Technologies in Language Teaching), a European Lifelong Learning Project, has two main aims: (a) to promote "best…

  11. Tilted Bianchi type I dust fluid cosmological model in general relativity

    Indian Academy of Sciences (India)

    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 = between metric potentials. The physical and geometrical aspects of the model together with singularity in the model are also ...

  12. Control and flight test of a tilt-rotor unmanned aerial vehicle

    Directory of Open Access Journals (Sweden)

    Chao Chen

    2017-01-01

    Full Text Available Tilt-rotor unmanned aerial vehicles have attracted increasing attention due to their ability to perform vertical take-off and landing and their high-speed cruising abilities, thereby presenting broad application prospects. Considering portability and applications in tasks characterized by constrained or small scope areas, this article presents a compact tricopter configuration tilt-rotor unmanned aerial vehicle with full modes of flight from the rotor mode to the fixed-wing mode and vice versa. The unique multiple modes make the tilt-rotor unmanned aerial vehicle a multi-input multi-output, non-affine, multi-channel cross coupling, and nonlinear system. Considering these characteristics, a control allocation method is designed to make the controller adaptive to the full modes of flight. To reduce the cost, the accurate dynamic model of the tilt-rotor unmanned aerial vehicle is not obtained, so a full-mode flight strategy is designed in view of this situation. An autonomous flight test was conducted, and the results indicate the satisfactory performance of the control allocation method and flight strategy.

  13. Experimental Investigation of the Performance of Tilt Current Meters in Wave-Dominated Flows

    DEFF Research Database (Denmark)

    Hansen, Asger Bendix; Carstensen, Stefan

    2017-01-01

    In recent years, tilt current meters (TCMs) have received renewed attention as they provide an inexpensive method for measuring currents in the coastal zone. However, previous studies focused mainly on current dominated flows or the current component of the flow. This study investigates the perfo...

  14. The Trapping of Helium at a Low Angle Tilt Boundary in Molybdenum

    NARCIS (Netherlands)

    Evans, J.H.; Veen, A. van; Hosson, J.Th.M. De; Bullough, R.; Willis, J.R.

    1984-01-01

    This paper presents experimental evidence of helium trapping at a set of b = [100] edge dislocations defining a low angle tilt boundary in molybdenum together with theoretical results on two aspects of helium-dislocation behaviour. The low angle boundary, with a misfit angle of ≈1/5 °, was found

  15. Equivalences from tilting theory and commutative algebra from the adjoint functor point of view

    DEFF Research Database (Denmark)

    Celikbas, Olgur; Holm, Henrik

    2017-01-01

    We give a category theoretic approach to several known equivalences from (classic) tilting theory and commutative algebra. Furthermore, we apply our main results to establish a duality theory for relative Cohen Macaulay modules in the sense of Hellus, Schenzel, and Z argar....

  16. Signature of tilted Dirac cones in Weiss oscillations of 8 -P m m n borophene

    Science.gov (United States)

    Islam, SK Firoz; Jayannavar, A. M.

    2017-12-01

    Polymorph of 8 -P m m n borophene exhibits anisotropic tilted Dirac cones. In this work, we explore the consequences of the tilted Dirac cones in magnetotransport properties of a periodically modulated borophene. We evaluate modulation-induced diffusive conductivity by using linear response theory in low temperature regime. The application of weak spatial modulation (electric, magnetic or both) gives rise to the magnetic-field-dependent nonzero oscillatory drift velocity which causes Weiss oscillation in the longitudinal conductivity at low magnetic field. The Weiss oscillation is studied in the presence of a weak spatial electric, magnetic, and both modulations individually. The tilting of the Dirac cones gives rise to an additional contribution to the Weiss oscillation in longitudinal conductivity. Moreover, it also enhances the frequency of the Weiss oscillation and modifies its amplitude too. Most remarkably, it is found that the presence of both out-of-phase electric and magnetic modulations can cause a sizable valley polarization in diffusive conductivity. The origin of valley polarization lies in the opposite tilting of the two Dirac cones at two valleys.

  17. Impact of mechanical down tilt and height on the pilot coverage of ...

    African Journals Online (AJOL)

    The task of planning a network can be very challenging as it involves many careful studies with a lot of considerations and, at times, trial and error. In this paper, the impacts of antenna mechanical down tilt and antenna height on UMTS network performance are studied. First, we used ASSET3G simulation software to design ...

  18. Relationship Between Anterior Lamina Cribrosa Surface Tilt and Glaucoma Development in Myopic Eyes.

    Science.gov (United States)

    Lee, Eun Jung; Han, Jong Chul; Kee, Changwon

    2017-05-01

    To evaluate the anterior lamina cribrosa (LC) surface tilt angle in myopic eyes and associate it with glaucoma development. In this retrospective study, medical records of myopic patients referred for glaucoma examination from July 1, 2012 to March 30, 2016 were reviewed. Comprehensive ophthalmic examination including spectral-domain optical coherence tomography were performed. We measured the angle of anterior LC surface tilt against Bruch's membrane opening from optical coherence tomography images at the center of the clinical optic disc margin. In horizontal and vertical sections, the angles were defined as α and β, respectively. Patients were grouped according to the presence of glaucomatous damage and factors including optic nerve head morphologic parameters and LC tilt angles were compared between the 2 groups. Among 138 patients originally enrolled, 102 patients were finally analyzed. One eye from 1 patient was randomly chosen. Fifty-five eyes had glaucoma and 47 were normal. The degree of myopia and all optic nerve head morphologic parameters were not significantly different between the 2 groups. However, |α| and |β| were significantly larger in the glaucoma group (all Pglaucoma in normal-pressure myopic eyes. Angulation of the LC against Bruch's membrane opening plane might be associated with increased glaucoma susceptibility in myopic eyes. Further investigations are warranted before clinical utilization of LC tilt as glaucoma susceptibility biomarker.

  19. The Tilt between Acretion Disk and Stellar Disk Shiyin Shen1,2 ...

    Indian Academy of Sciences (India)

    to a control galaxy sample. Given that the Type 2 AGN fraction is in the range of 70–90 percent for low luminosity AGNs as a priori, we find that the mean tilt between the accretion disk and stellar disk is ∼ 30 degrees. (Shen et al. 2010). Key words. Galaxies: statistics—galaxies: Seyfert—galaxies: nuclei— galaxies: spiral. 1.

  20. Optimal Tilt Angle and Orientation of Photovoltaic Modules Using HS Algorithm in Different Climates of China

    Directory of Open Access Journals (Sweden)

    Mian Guo

    2017-10-01

    Full Text Available Solar energy technologies play an important role in shaping a sustainable energy future, and generating clean, renewable, and widely distributed energy sources. This paper determines the optimum tilt angle and optimum azimuth angle of photovoltaic (PV panels, employing the harmony search (HS meta-heuristic algorithm. In this study, the ergodic method is first conducted to obtain the optimum tilt angle and the optimum azimuth angle in several cities of China based on the model of Julian dating. Next, the HS algorithm is applied to search for the optimum solution. The purpose of this research is to maximize the extraterrestrial radiation on the collector surface for a specific period. The sun’s position is predicted by the proposed model at different times, and then solar radiation is obtained on various inclined planes with different orientations in each city. The performance of the HS method is compared with that of the ergodic method and other optimization algorithms. The results demonstrate that the tilt angle should be changed once a month, and the best orientation is usually due south in the selected cities. In addition, the HS algorithm is a practical and reliable alternative for estimating the optimum tilt angle and optimum azimuth angle of PV panels.

  1. An iterative, fast-sweeping-based eikonal solver for 3D tilted anisotropic media

    KAUST Repository

    Waheed, Umair bin

    2015-03-30

    Computation of first-arrival traveltimes for quasi-P waves in the presence of anisotropy is important for high-end near-surface modeling, microseismic-source localization, and fractured-reservoir characterization - and it requires solving an anisotropic eikonal equation. Anisotropy deviating from elliptical anisotropy introduces higher order nonlinearity into the eikonal equation, which makes solving the eikonal equation a challenge. We addressed this challenge by iteratively solving a sequence of simpler tilted elliptically anisotropic eikonal equations. At each iteration, the source function was updated to capture the effects of the higher order nonlinear terms. We used Aitken\\'s extrapolation to speed up convergence rate of the iterative algorithm. The result is an algorithm for computing first-arrival traveltimes in tilted anisotropic media. We evaluated the applicability and usefulness of our method on tilted transversely isotropic media and tilted orthorhombic media. Our numerical tests determined that the proposed method matches the first arrivals obtained by wavefield extrapolation, even for strongly anisotropic and highly complex subsurface structures. Thus, for the cases where two-point ray tracing fails, our method can be a potential substitute for computing traveltimes. The approach presented here can be easily extended to compute first-arrival traveltimes for anisotropic media with lower symmetries, such as monoclinic or even the triclinic media.

  2. PVC stay-in-place panel covers for tilt-up and pre-cast construction

    OpenAIRE

    ECT Team, Purdue

    2012-01-01

    Octaform™ stay-in-place concrete forming system is PVC insulated concrete form system. These forms have been used in the industry for various applications to improve the insulation and corrosion resistance of structures. Octaform™ has developed the panel covers so the advantages of PVC stay-in-place concrete forming systems could be applied to tilt-up and pre-cast construction.

  3. An Approximate Cone Beam Reconstruction Algorithm for Gantry-Tilted CT Using Tangential Filtering

    Directory of Open Access Journals (Sweden)

    Ming Yan

    2006-01-01

    Full Text Available FDK algorithm is a well-known 3D (three-dimensional approximate algorithm for CT (computed tomography image reconstruction and is also known to suffer from considerable artifacts when the scanning cone angle is large. Recently, it has been improved by performing the ramp filtering along the tangential direction of the X-ray source helix for dealing with the large cone angle problem. In this paper, we present an FDK-type approximate reconstruction algorithm for gantry-tilted CT imaging. The proposed method improves the image reconstruction by filtering the projection data along a proper direction which is determined by CT parameters and gantry-tilted angle. As a result, the proposed algorithm for gantry-tilted CT reconstruction can provide more scanning flexibilities in clinical CT scanning and is efficient in computation. The performance of the proposed algorithm is evaluated with turbell clock phantom and thorax phantom and compared with FDK algorithm and a popular 2D (two-dimensional approximate algorithm. The results show that the proposed algorithm can achieve better image quality for gantry-tilted CT image reconstruction.

  4. Tilting at Windmills: School Reform, San Diego, and America?s Race to Renew Public Education

    Science.gov (United States)

    Colvin, Richard Lee

    2013-01-01

    A book that draws equally on Richard Lee Colvin's deep acquaintance with contemporary education reform and the unique circumstances of the San Diego experience, "Tilting at Windmills" is a penetrating and invaluable account of Alan Bersin's contentious superintendency. Between 1998, when Alan Bersin became superintendent of the San Diego…

  5. Active tilting-pad journal bearings supporting flexible rotors: Part I – The hybrid lubrication

    DEFF Research Database (Denmark)

    Salazar, Jorge Andrés González; Santos, Ilmar

    2017-01-01

    This is part I of a twofold paper series, of theoretical and experimental nature, presenting the design and implementation of model-based controllers meant for assisting the hybrid and developing the feedback-controlled lubrication regimes in active tilting-pad journal bearings (active TPJBs). In...

  6. Proto-CIRCUS Tilted-Coil Tokamak-Torsatron Hybrid: Design and Construction

    CERN Document Server

    Clark, A W; Hammond, K C; Kornbluth, Y; Spong, D A; Sweeney, R; Volpe, F A

    2014-01-01

    We present the field-line modeling, design and construction of a prototype circular-coil tokamak-torsatron hybrid called Proto-CIRCUS. The device has a major radius R = 16 cm and minor radius a < 5 cm. The six "toroidal field" coils are planar as in a tokamak, but they are tilted. This, combined with induced or driven plasma current, is expected to generate rotational transform, as seen in field-line tracing and equilibrium calculations. The device is expected to operate at lower plasma current than a tokamak of comparable size and magnetic field, which might have interesting implications for disruptions and steady-state operation. Additionally, the toroidal magnetic ripple is less pronounced than in an equivalent tokamak in which the coils are not tilted. The tilted coils are interlocked, resulting in a relatively low aspect ratio, and can be moved, both radially and in tilt angle, between discharges. This capability will be exploited for detailed comparisons between calculations and field-line mapping me...

  7. Tilted Kantowski-Sachs cosmological model in Brans-Dicke theory of gravitation

    Science.gov (United States)

    Pawar, D. D.; Shahare, S. P.; Dagwal, V. J.

    2018-02-01

    Tilted Kantowski-Sachs cosmological model in Brans-Dicke theory for perfect fluid has been investigated. The general solution of field equations in Brans-Dicke theory for the combined scalar and tensor field are obtained by using power law relation. Also, some physical and geometrical parameters are obtained and discussed.

  8. How to use body tilt for the simulation of linear self motion

    NARCIS (Netherlands)

    Groen, E.L.; Bles, W.

    2004-01-01

    We examined to what extent body tilt may augment the perception of visually simulated linear self acceleration. Fourteen subjects judged visual motion profiles of fore-aft motion at four different frequencies between 0.04-0.33 Hz, and at three different acceleration amplitudes (0.44, 0.88 and 1.76

  9. Exploring a possible origin of a 14 deg y-normal spin tilt at RHIC polarimeter

    Energy Technology Data Exchange (ETDEWEB)

    Meot, F. [Brookhaven National Lab. (BNL), Upton, NY (United States); Huang, H. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-06-15

    A possible origin of a 14 deg y-normal spin n0 tilt at the polarimeter is in snake angle defects. This possible cause is investigated by scanning the snake axis angle µ, and the spin rotation angle at the snake, φ, in the vicinity of their nominal values.

  10. Properties of the internal representation of gravity inferred from spatial-direction and body-tilt estimates.

    Science.gov (United States)

    Van Beuzekom, A D; Van Gisbergen, J A

    2000-07-01

    One of the key questions in spatial perception is whether the brain has a common representation of gravity that is generally accessible for various perceptual orientation tasks. To evaluate this idea, we compared the ability of six tilted subjects to indicate earth-centric directions in the dark with a visual and an oculomotor paradigm and to estimate their body tilt relative to gravity. Subjective earth-horizontal and -vertical data were collected, either by adjusting a visual line or by making saccades, at 37 roll-tilt angles across the entire range. These spatial perception responses and the associated body-tilt estimates were subjected to a principal-component analysis to describe their tilt dependence. This analysis allowed us to separate systematic and random errors in performance, to disentangle the effects of task (horizontal vs. vertical) and paradigm (visual vs. oculomotor) in the space-perception data, and to compare the veridicality of space perception and the sense of self-tilt. In all spatial-orientation tests, whether involving space-perception or body-tilt judgments, subjects made considerable systematic errors which mostly betrayed tilt underestimation [Aubert effect (A effect)] and peaked near 130 degrees tilt. However, the A effect was much smaller in body-tilt estimates than in spatial pointing, implying that the underlying signal processing must have been different. Pointing results obtained with the visual and the oculomotor paradigm were not identical either, but these differences, which were task-related (horizontal vs. vertical), were subtle in comparison. The tilt-dependent pattern of random errors (noisy scatter) was almost identical in visual and oculomotor pointing results, showing a steep monotonic increase with tilt angle, but was again clearly different in the body-tilt estimates. These findings are discussed in the context of a conceptual model in an attempt to explain how the different patterns of systematic and random errors in

  11. Gravity influences the visual representation of object tilt in parietal cortex.

    Science.gov (United States)

    Rosenberg, Ari; Angelaki, Dora E

    2014-10-22

    Sensory systems encode the environment in egocentric (e.g., eye, head, or body) reference frames, creating inherently unstable representations that shift and rotate as we move. However, it is widely speculated that the brain transforms these signals into an allocentric, gravity-centered representation of the world that is stable and independent of the observer's spatial pose. Where and how this representation may be achieved is currently unknown. Here we demonstrate that a subpopulation of neurons in the macaque caudal intraparietal area (CIP) visually encodes object tilt in nonegocentric coordinates defined relative to the gravitational vector. Neuronal responses to the tilt of a visually presented planar surface were measured with the monkey in different spatial orientations (upright and rolled left/right ear down) and then compared. This revealed a continuum of representations in which planar tilt was encoded in a gravity-centered reference frame in approximately one-tenth of the comparisons, intermediate reference frames ranging between gravity-centered and egocentric in approximately two-tenths of the comparisons, and in an egocentric reference frame in less than half of the comparisons. Altogether, almost half of the comparisons revealed a shift in the preferred tilt and/or a gain change consistent with encoding object orientation in nonegocentric coordinates. Through neural network modeling, we further show that a purely gravity-centered representation of object tilt can be achieved directly from the population activity of CIP-like units. These results suggest that area CIP may play a key role in creating a stable, allocentric representation of the environment defined relative to an "earth-vertical" direction. Copyright © 2014 the authors 0270-6474/14/3414170-11$15.00/0.

  12. Long-period tilt-induced accelerations associated with hydraulic fracturing

    Science.gov (United States)

    Milkereit, Claus; Dahm, Torsten; Cesca, Simone; Lopez, Jose; Nooshiri, Nima; Zang, Arno

    2017-04-01

    In 2015, several small scale hydrofracture experiments have been performed in situ from a horizontal borehole in a mine gallery in granitic rock. The hydrofracture experiments were monitored by a bundle of different near field sensors covering a broad range of frequencies (see Zang et al., Geophys. J. Int. (2017) 208, 790-813, doi: 10.1093/gji/ggw430). We installed broad band sensors in the gallery close to the fracture experiments, and observed clear long period transients on the horizontal components, with timing and polarity correlated with the opening and closing of the fractures. We interpret the broadband signals as tilt-induced excursions. The broadband signals have been measured independent whether high frequency acoustic emission have been observed or not during the individual fracture experiments. They are thus an independent measure of the success of a hydrofracture experiment and the parameter of the newly formed cracks. In this study we show that most tilt-induced long-period signals can be modeled by a rectangular crack with constant opening in an elastic full space, as first order approximation. From theoretical forward modeling, we proof that the tilt has a higher sensitivity to resolve the strike of the fracture than the displacement field. With this model, we retrieve the strike of the fractures from the tilt observed at a single sensor. The results indicate that the strike angles of the hydrofractures change systematically with the distance to the gallery wall, indicating a rotation of the principal stresses close to the free surface of the gallery. The rotation trend is similar to the one observed in previous hydrofracture experiments in mines. We compare the strength of the modeled tensile cracks, i.e. opening times crack area, with the volume of the injected fluid, and discuss the general resolving power of tilt signals for source parameter fractures. The temporal evolution of the opening and closure of the fractures is discussed.

  13. Lake level observations to detect crustal tilt: San Andreas Lake, California, 1979-1989

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, R.J.; Johnston, M.J.S.; Myren, G.D. (Geological Survey, Menlo Park, CA (USA)); Murray, T. (Cascades Volcano Observatory, Vancouver, WA (USA))

    1989-07-01

    A pair precision lake level gauging stations, installed in 1978, have been monitoring differential crustal uplift (crustal tilt) at San Andreas lake, California, near the suspected epicenter on the San Andreas fault of the M = 8.3, 1906 San Francisco earthquake. The stations are installed in the lake with a 4.2 km station separation parallel to the San Andreas fault. The gauging stations use quartz pressure transducers that are capable of detecting intermediate to long-term vertical displacements greater than 0.4 mm relative to a fluid surface. Differencing data from the two sites reduces the noise contributed by atmospheric pressure, temperature, and density changes, and isolates the relative elevation changes between the ends of the lake. At periods less than 20 minutes, the differenced data are dominated by lake seiches which have a fundamental mode at a period of 13 {plus minus} 0.3 minutes. These seiche harmonics can be filtered or predicted and removed from the data. Wind shear, typically lasting several days, can generate apparent short term tilt of the lake and large seiche amplitudes. The tilt noise power spectrum obtained from these data decreases by about 15 dB/decade of frequency. Monthly averages of the data between 1979-1989 indicate a tilt rate of 0.02 {plus minus} 0.08 microradians/yr (down S34{degree}E). No measurable horizontal tilt has apparently occurred in this region of the San Andreas fault during the last decade, however, measurements of trilateration networks show this region to be undergoing a horizontal strain of 0.6 {plus minus} 0.2 {mu}strain/yr.

  14. Renormalization of Coulomb interactions in a system of two-dimensional tilted Dirac fermions

    Science.gov (United States)

    Lee, Yu-Wen; Lee, Yu-Li

    2018-01-01

    We investigate the effects of long-ranged Coulomb interactions in a tilted Dirac semimetal in two dimensions by using the perturbative renormalization-group (RG) method. Depending on the magnitude of the tilting parameter, the undoped system can have either Fermi points (type I) or Fermi lines (type II). Previous studies usually performed the renormalization-group transformations by integrating out the modes with large momenta. This is problematic when the Fermi surface is open, like type-II Dirac fermions. In this work we study the effects of Coulomb interactions, following the spirit of Shankar [Rev. Mod. Phys. 66, 129 (1994), 10.1103/RevModPhys.66.129], by introducing a cutoff in the energy scale around the Fermi surface and integrating out the high-energy modes. For type-I Dirac fermions, our result is consistent with that of the previous work. On the other hand, we find that for type-II Dirac fermions, the magnitude of the tilting parameter increases monotonically with lowering energies. This implies the stability of type-II Dirac fermions in the presence of Coulomb interactions, in contrast with previous results. Furthermore, for type-II Dirac fermions, the velocities in different directions acquire different renormalization even if they have the same bare values. By taking into account the renormalization of the tilting parameter and the velocities due to the Coulomb interactions, we show that while the presence of a charged impurity leads only to charge redistribution around the impurity for type-I Dirac fermions, for type-II Dirac fermions, the impurity charge is completely screened, albeit with a very long screening length. The latter indicates that the temperature dependence of physical observables are essentially determined by the RG equations we derived. We illustrate this by calculating the temperature dependence of the compressibility and specific heat of the interacting tilted Dirac fermions.

  15. Surface Electromyographic Activity of the Abdominal Muscles During Pelvic-Tilt and Abdominal-Hollowing Exercises.

    Science.gov (United States)

    Drysdale, Cheri L.; Earl, Jennifer E.; Hertel, Jay

    2004-03-01

    OBJECTIVE: To investigate surface electromyographic (EMG) activity of the rectus abdominus and external oblique abdominus muscles during pelvic-tilt and abdominal-hollowing exercises performed in different positions. DESIGN AND SETTING: 2 x 3 (exercise by position) within-subjects design with repeated measures on both factors. All testing was performed in a university laboratory. SUBJECTS: Twenty-six healthy, active young adult females. MEASUREMENTS: Surface EMG activity was recorded from the left and right rectus abdominus and external oblique muscles while the 2 exercises (pelvic tilt and abdominal hollowing) were performed in different positions (standard, legs supported, and legs unsupported). The standard position was supine in the crook-lying position, the supported position was with hips and knees flexed to 90 degrees and legs supported on a platform, and the unsupported position was with hips and knees flexed to 90 degrees without external support. Peak EMG activity was normalized to a maximum voluntary isometric contraction for each muscle. RESULTS: For the rectus abdominus, there was an interaction between position and activity. Abdominal hollowing produced significantly less activity than the pelvic tilt in all positions. The difference between the 2 exercises with the legs unsupported was of a greater magnitude than the other 2 positions. For the external obliques, there was significantly lower activity during the abdominal hollowing compared with the pelvic tilting. The greatest muscle activity occurred with the legs-unsupported position during both exercises. CONCLUSIONS: Abdominal-hollowing exercises produced less rectus abdominus and external oblique activity than pelvic-tilting exercises. Abdominal hollowing may be performed with minimal activation of the large global abdominal muscles.

  16. Effect of Individual Strengthening Exercises for Anterior Pelvic Tilt Muscles on Back Pain, Pelvic Angle, and Lumbar ROMs of a LBP Patient with Flat Back

    National Research Council Canada - National Science Library

    Yoo, Won-gyu

    2013-01-01

    [Purpose] The purpose of this paper is to report the effect of individual strengthening exercises for the anterior pelvic tilt muscles on back pain, pelvic tilt angle, and lumbar ROM of a low back pain (LBP...

  17. To tilt or not to tilt: Correction of the distortion caused by inclined sample surfaces in low-energy electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Sojka, Falko, E-mail: falko.sojka@uni-jena.de [Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 5, 07743 Jena (Germany); Meissner, Matthias; Zwick, Christian; Forker, Roman [Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 5, 07743 Jena (Germany); Vyshnepolsky, Michael; Klein, Claudius; Horn-von Hoegen, Michael [University of Duisburg-Essen, Department of Physics, Lotharstr. 1, 47057 Duisburg (Germany); Fritz, Torsten, E-mail: torsten.fritz@uni-jena.de [Friedrich Schiller University Jena, Institute of Solid State Physics, Helmholtzweg 5, 07743 Jena (Germany)

    2013-10-15

    Low-energy electron diffraction (LEED) is a widely employed technique for the structural characterization of crystalline surfaces and epitaxial adsorbates. For technical reasons the accessible reciprocal space is limited at a given primary electron energy E. This limitation may be overcome by sweeping E to observe higher diffraction orders decisively enhancing the quantitative examination. Yet, in many cases, such as molecular films with rather large unit cells, the adsorbate reflexes become less pronounced at energies high enough to observe substrate reflexes. One possibility to overcome this problem is an intentional inclination of the sample surface during the measurement at the expense of the quantitative interpretability of then severely distorted diffraction patterns. Here, we introduce a correction method for the axially symmetric distortion in LEED images of tilted samples. We provide experimental confirmation for micro-channel plate LEED and spot-profile analysis LEED instruments using the (7×7) reconstructed surface of a Si(111) single crystal as a reference sample. Finally, we demonstrate that the correction of this distortion considerably improves the quantitative analysis of diffraction patterns of adsorbates since substrate and adsorbate reflexes can be evaluated simultaneously. As an illustrative example we have chosen an epitaxial monolayer of 3,4,9,10-perylenetetracarboxylic dianhydride on Ag(111) that is known to form a commensurate superstructure. - Highlights: • We introduce a method to correct distortions in LEED patterns of tilted surfaces. • Higher diffraction orders unobservable at higher beam energies can be evaluated. • Our procedure makes LEED patterns of tilted samples quantitatively analyzable. • Experimental confirmation with SPA-LEED and MCP-LEED is presented. • The method is applied to PTCDA on Ag(111) confirming earlier literature values.

  18. Exploring the Tilt-Angle Dependence of electron tunneling across Molecular junction of Self-Assembled Alkanethiols

    DEFF Research Database (Denmark)

    Frederiksen, Thomas; Munuera, C.; Ocal, C.

    2009-01-01

    by contacting the molecular layers with the tip of a conductive force microscope. Measurements done under low-load conditions permit us to obtain reliable tilt-angle and molecular length dependencies of the low-bias conductance through the alkanethiol layers. The observed dependence on tilt-angle is stronger...... for the longer molecular chains. Our calculations confirm the observed trends and explain them as a result of two mechanisms, namely, a previously proposed intermolecular tunneling enhancement as well as a hitherto overlooked tilt-dependent molecular gate effect....

  19. De novo formation of left-right asymmetry by posterior tilt of nodal cilia.

    Directory of Open Access Journals (Sweden)

    Shigenori Nonaka

    2005-08-01

    Full Text Available In the developing mouse embryo, leftward fluid flow on the ventral side of the node determines left-right (L-R asymmetry. However, the mechanism by which the rotational movement of node cilia can generate a unidirectional flow remains hypothetical. Here we have addressed this question by motion and morphological analyses of the node cilia and by fluid dynamic model experiments. We found that the cilia stand, not perpendicular to the node surface, but tilted posteriorly. We further confirmed that such posterior tilt can produce leftward flow in model experiments. These results strongly suggest that L-R asymmetry is not the descendant of pre-existing L-R asymmetry within each cell but is generated de novo by combining three sources of spatial information: antero-posterior and dorso-ventral axes, and the chirality of ciliary movement.

  20. 19 years of tilt data on Mt. Vesuvius: state of the art and future perspectives

    Directory of Open Access Journals (Sweden)

    Ciro Ricco

    2013-11-01

    Full Text Available Mt. Vesuvius, located along the SW border of the Campania Plane graben, is one of the most studied volcanoes worldwide, from both the volcanological and the geophysical, geochemical and geodetic point of view. In order to better understand its dynamics, the deformation of the volcano has been already studied since the early ’70s by setting up levelling lines and, since a few years later, through trilateration networks, whereas ground tilt monitoring started in 1993. Tilt variations were recorded by an automatic surface station set up at the Osservatorio Vesuviano (O.V. bunker (OVO and data recorded were transmitted to the O.V. Surveillance Centre in Naples. Afterwards, in 1996 two more identical stations were set up close to Torre del Greco (CMD, and close to Trecase (TRC. In 2002 the data acquisition system was replaced, while at the end of 2011 a Lily borehole sensor was set up at 26 m depth, replacing the old TRC tilt station. The paper describes in details the tilt network of Mt. Vesuvius, its development over time and the data processing procedure; moreover, the ground deformation pattern is discussed, as inferred from the study of 19 years of data and its change during the seismic crises of 1995-1996 and 1999-2000. From the information obtained from the tiltmetric monitoring, a complex deformation pattern can be deduced, strongly dependent on the position of the sites in which the sensors were set up with respect to the morphology of the volcanic edifice and its structural outlines. If we consider the signals as they were recorded, although previously corrected for the influences of the thermo-elastic strain on the sensors, the tilting occurs mainly in the SW direction with rates of about 11 µradians/year on both the western and eastern flanks and of about 13 µradians/year on the southern one. Because tilt vectors point in the long term outward from the summit and towards the subsiding area, this supports the hypothesis of a southern

  1. Frequency Response Analysis of an Actively Lubricated Rotor/Tilting-Pad Bearing System

    DEFF Research Database (Denmark)

    Nicoletti, Rodrigo; Santos, Ilmar

    2004-01-01

    into the model by using two different approaches: (a) linearized active oil film forces and the assumption that the hydrodynamic forces and the active hydraulic forces can be decoupled; (b) equivalent dynamic coefficients of the active oil film and the solution of the modified Reynolds' equation for the active......In the present paper, the dynamic response of a rotor supported by an active lubricated tilting-pad bearing is investigated in the frequency domain. The theoretical part of the investigation is based on a mathematical model obtained by means of rigid body dynamics. The oil film forces are inserted...... lubrication. The second approach based on the equivalent dynamic coefficients leads to more accurate results since it includes the frequency dependence of the active hydraulic forces. Theoretical and experimental results reveal the feasibility of reducing resonance peaks by using the active lubricated tilting...

  2. Surface tension-induced PDMS micro-pillars with controllable tips and tilt angles

    KAUST Repository

    Li, Huawei

    2013-12-21

    This paper reports a novel method to fabricate three-dimensional (3D) polydimethylsiloxane (PDMS) micro-pillars using a CO2 laser-machined poly(methyl methacrylate) (PMMA) mold with through-holes. This method eliminates the requirements of expensive and complicated facilities to fabricate a 3D mold. The micro-pillars were formed by the capillary force that draws PDMS into the through-holes of the PMMA mold. The tilt angles of the micro-pillars depend on the tilt angles of the through-holes in the mold, and the concave and convex micro-lens tip shapes of the PDMS micro-pillars can be modified by changing the surface wettability of the PMMA through-holes.

  3. Effects of thickness and external refractive index in coated tilted fiber Bragg gratings

    Science.gov (United States)

    Paladino, D.; Pilla, P.; Cutolo, A.; Campopiano, S.; Giordano, M.; Cusano, A.; Caucheteur, C.; Mégret, P.

    2007-07-01

    In this work, an experimental analysis on the spectral effects induced by depositing a uniform high refractive index (HRI) thin coating on weakly tilted fiber Bragg gratings (TFBGs) is carried out. First, two weakly TFBGs presenting different tilt angles were fabricated. Successively, by using dip-coating technique, two different coating thicknesses were deposited on each of them. The transmission spectra of the obtained structures were collected as the surrounding refractive index (SRI) changed in the range 1÷1.47. The coated gratings present some differences in their spectral evolution, that can be opportunely exploited. The coated configuration could improve some aspects of previous demodulation techniques exploited in the case of bare TFBGs. Moreover, an important effect of HRI coatings is to enhance the SRI sensitivity of the spectral position of the dips corresponding to cladding modes coupling, leading to a different interrogation method for sensing applications.

  4. Novel interrogation technique for Tilted Fiber Bragg Gratings sensors based on single wavelength time delay measurements

    Science.gov (United States)

    Pisco, M.; Ricciardi, A.; Campopiano, S.; Caucheteur, C.; Mégret, P.; Cutolo, A.; Cusano, A.

    2009-10-01

    A novel interrogation scheme for Tilted Fiber Bragg Gratings (TFBGs) sensors is here proposed based on single wavelength time delay measurements. To this aim, the group delay of a weakly tilted TFBG has been characterized by direct time domain measurement. The experimental characterization shows the capability of TFBGs to enable superluminal and subluminal propagation of an optical pulse in optical fibers. The sharp group delay features of the TFBGs are exploited for refractometric applications to detect the SRI variations by single wavelength time delay measurements. The obtained preliminary results demonstrate the possibility to detect SRI changes by means of single wavelength time delay measurements with a sensitivity enhanced in the range 1.33-1.40 with respect to previously reported interrogation techniques.

  5. On the feasibility of photon-limited tip-tilt correction in very small telescopes

    Science.gov (United States)

    Popowicz, A.; Orlov, V. G.

    2017-10-01

    The resolution of astronomical images taken from the ground is severely degraded by the atmosphere. One of the simplest methods for overcoming this problem is tip-tilt (TT) correction. This method is especially valuable for small telescopes, as it enables them to reach their diffraction limit. Unfortunately, the method requires a bright guide star to asses the blurring of astronomical images. In this study we show how various factors influence the feasibility of tip-tilt correction in very small telescopes (≤ 1 m). We evaluate the effect of: (1) the intensity of the guide star, (2) seeing conditions, (3) telescope size and (4) sky background. The results are obtained from data simulated using the Random Wave Vector method. The dependencies presented in this paper can be used to predict the sky coverage of small telescopes with TT correction for a wide range of observational conditions.

  6. Mapping misorientation and crystallographic tilt in GaN layers via polychromatic microdiffraction

    Energy Technology Data Exchange (ETDEWEB)

    Barabash, R.I.; Ice, G.E.; Liu, W. [Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Roder, C.; Figge, S.; Einfeldt, S.; Hommel, D. [Institute of Solid State Physics, University of Bremen, P.O. Box 330 440, 28334 Bremen (Germany); Katona, T.M. [Electrical and Computer Engineering Department, College of Engineering, University of California at Santa Barbara, Santa Barbara, CA 93106 (United States); Speck, J.S.; DenBaars, S.P. [Materials Department, College of Engineering, University of California at Santa Barbara, Santa Barbara, CA 93106 (United States); Davis, R.F. [Materials Science and Engineering Department, North Carolina State University, Raleigh (United States)

    2006-06-15

    The spatial distribution of strain, dislocations, and crystallographic orientation in uncoalesced and coalesced GaN layers grown on striped Si or SiC substrates was studied by polychromatic X-ray microdiffraction and high resolution monochromatic X-ray diffraction. Tilt boundaries formed at the column/wing interface depending on the growth conditions and geometry of the striped substrate. The measurements revealed that the free-hanging wings are tilted upward at room temperature. A misorientation between the GaN(0001) and the Si(111) or SiC(0001) surface normal is observed. Distinct structural properties of the pendeo and cantilever epitaxially grown samples are discussed. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Motorcycle That See: Multifocal Stereo Vision Sensor for Advanced Safety Systems in Tilting Vehicles

    Directory of Open Access Journals (Sweden)

    Gustavo Gil

    2018-01-01

    Full Text Available Advanced driver assistance systems, ADAS, have shown the possibility to anticipate crash accidents and effectively assist road users in critical traffic situations. This is not the case for motorcyclists, in fact ADAS for motorcycles are still barely developed. Our aim was to study a camera-based sensor for the application of preventive safety in tilting vehicles. We identified two road conflict situations for which automotive remote sensors installed in a tilting vehicle are likely to fail in the identification of critical obstacles. Accordingly, we set two experiments conducted in real traffic conditions to test our stereo vision sensor. Our promising results support the application of this type of sensors for advanced motorcycle safety applications.

  8. Design Optimization of Tilting-Pad Journal Bearing Using a Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Hamit Saruhan

    2004-01-01

    Full Text Available This article focuses on the use of genetic algorithms in developing an efficient optimum design method for tilting pad bearings. The approach optimizes based on minimum film thickness, power loss, maximum film temperature, and a global objective. Results for a five tilting-pad preloaded bearing are presented to provide a comparison with more traditional optimum design methods such as the gradient-based global criterion method, and also to provide insight into the potential of genetic algorithms in the design of rotor bearings. Genetic algorithms are efficient search techniques based on the idea of natural selection and genetics. These robust methods have gained recognition as general problem solving techniques in many applications.

  9. Head Tilting Elicited by Head Turning in Three Dogs with Hypoplastic Cerebellar Nodulus and Ventral Uvula

    Directory of Open Access Journals (Sweden)

    Shinji Tamura

    2016-11-01

    Full Text Available The nodulus and ventral uvula (NU of the cerebellum play a major role in vestibular function in humans and experimental animals; however, there is almost no information about NU function in the veterinary clinical literature. In this report, we describe three canine cases diagnosed with presumptive NU hypoplasia. Of them, one adult dog presented with cervical intervertebral disk disease, and two juvenile dogs presented with signs of central vestibular disease. Interestingly, an unusual and possibly overlooked neurological sign that we called positioning head tilt was observed in these dogs. The dogs were able to turn freely in any direction at will. The head was in a level position when static or when the dog walked in a straight line. However, the head was tilted to the opposite side when the dog turned. Veterinary clinicians should be aware of this neurological sign, which has not been reported previously, and its application in lesion localization in dogs.

  10. The current perception thresholds vary between horizontal and 70 degrees tilt-up positions.

    Science.gov (United States)

    Shimoda, O; Ikuta, Y

    2000-08-01

    We investigated the influence of posture on current perception threshold (CPT). The subjects consisted of 20 healthy male volunteers (23-31 yr old). At both the horizontal and the 70 degrees tilt-up position (TUP), the CPTs (5, 250, and 2000 Hz) of the middle finger were determined by using the Neurometer CPT/C (Neuropteran, Baltimore, MD). Autonomic nervous activities were evaluated by heart rate variability (HRV) analysis and spontaneous baroreflex sensitivity analysis at the two postures previously mentioned. The three CPTs at the 70 degrees TUP were significantly lower than those at the horizontal posture (5 Hz, P tilt-up posture were significantly lower than those at the horizontal posture. When the compensatory mechanism for preserving blood pressure was emphasized, the current perception thresholds would have a relational connection to mean systolic blood pressure, similar to the concept of hypertension-induced hypoalgesia.

  11. Motorcycle That See: Multifocal Stereo Vision Sensor for Advanced Safety Systems in Tilting Vehicles.

    Science.gov (United States)

    Gil, Gustavo; Savino, Giovanni; Piantini, Simone; Pierini, Marco

    2018-01-19

    Advanced driver assistance systems, ADAS, have shown the possibility to anticipate crash accidents and effectively assist road users in critical traffic situations. This is not the case for motorcyclists, in fact ADAS for motorcycles are still barely developed. Our aim was to study a camera-based sensor for the application of preventive safety in tilting vehicles. We identified two road conflict situations for which automotive remote sensors installed in a tilting vehicle are likely to fail in the identification of critical obstacles. Accordingly, we set two experiments conducted in real traffic conditions to test our stereo vision sensor. Our promising results support the application of this type of sensors for advanced motorcycle safety applications.

  12. Motorcycles that See: Multifocal Stereo Vision Sensor for Advanced Safety Systems in Tilting Vehicles

    Science.gov (United States)

    2018-01-01

    Advanced driver assistance systems, ADAS, have shown the possibility to anticipate crash accidents and effectively assist road users in critical traffic situations. This is not the case for motorcyclists, in fact ADAS for motorcycles are still barely developed. Our aim was to study a camera-based sensor for the application of preventive safety in tilting vehicles. We identified two road conflict situations for which automotive remote sensors installed in a tilting vehicle are likely to fail in the identification of critical obstacles. Accordingly, we set two experiments conducted in real traffic conditions to test our stereo vision sensor. Our promising results support the application of this type of sensors for advanced motorcycle safety applications. PMID:29351267

  13. A note on tilted Bianchi type VIh models: the type III bifurcation

    Science.gov (United States)

    Coley, A. A.; Hervik, S.

    2008-10-01

    In this note we complete the analysis of Hervik, van den Hoogen, Lim and Coley (2007 Class. Quantum Grav. 24 3859) of the late-time behaviour of tilted perfect fluid Bianchi type III models. We consider models with dust, and perfect fluids stiffer than dust, and eludicate the late-time behaviour by studying the centre manifold which dominates the behaviour of the model at late times. In the dust case, this centre manifold is three-dimensional and can be considered a double bifurcation as the two parameters (h and γ) of the type VIh model are varied. We therefore complete the analysis of the late-time behaviour of tilted ever-expanding Bianchi models of types I VIII.

  14. Control of Pan-tilt Mechanism Angle using Position Matrix Method

    Directory of Open Access Journals (Sweden)

    Hendri Maja Saputra

    2013-12-01

    Full Text Available Control of a Pan-Tilt Mechanism (PTM angle for the bomb disposal robot Morolipi-V2 using inertial sensor measurement unit, x-IMU, has been done. The PTM has to be able to be actively controlled both manually and automatically in order to correct the orientation of the moving Morolipi-V2 platform. The x-IMU detects the platform orientation and sends the result in order to automatically control the PTM. The orientation is calculated using the quaternion combined with Madwick and Mahony filter methods. The orientation data that consists of angles of roll (α, pitch (β, and yaw (γ from the x-IMU are then being sent to the camera for controlling the PTM motion (pan & tilt angles after calculating the reverse angle using position matrix method. Experiment results using Madwick and Mahony methods show that the x-IMU can be used to find the robot platform orientation. Acceleration data from accelerometer and flux from magnetometer produce noise with standard deviation of 0.015 g and 0.006 G, respectively. Maximum absolute errors caused by Madgwick and Mahony method with respect to Xaxis are 48.45º and 33.91º, respectively. The x-IMU implementation as inertia sensor to control the Pan-Tilt Mechanism shows a good result, which the probability of pan angle tends to be the same with yaw and tilt angle equal to the pitch angle, except a very small angle shift due to the influence of roll angle..

  15. The cone phase of liquid crystals: Triangular lattice of double-tilt ...

    Indian Academy of Sciences (India)

    the cut-off α =20 ˚A, double-tilt cylinders of radius R <200 ˚A are energetically favoured over a distortion-free smectic-C provided κG < -3 x10 6 dyne. We are not aware of any measurements of κG in thermotropic liquid crystals. However, some lyotropic liquid crystals have κG values of this sign and magnitude [14]. It is clear ...

  16. Comparison of acute cardiovascular responses to water immersion and head-down tilt in humans

    DEFF Research Database (Denmark)

    Shiraishi, Makoto; Schou, Morten; Gybel, Mikkel

    2002-01-01

    , and renin activity were suppressed similarly. Mean arterial pressure decreased by 9 mmHg (P hypothesis......The hypothesis was tested that acute water immersion to the neck (WI) compared with 6 degrees head-down tilt (HDT) induces a more pronounced distension of the heart and lower plasma levels of vasoconstrictor hormones. Ten healthy males underwent 30 min of HDT, WI, and a seated control (randomized...

  17. Morphological classification of acromial spur: correlation between Rockwood tilt view and arthroscopic finding

    Directory of Open Access Journals (Sweden)

    Kongmalai Pinkawas

    2017-01-01

    Full Text Available Purpose and hypothesis: Acromion spur is the extrinsic factor for impingement syndrome and rotator cuff tear. The Rockwood tilt view can be used to evaluate prominence of the anterior acromion, however no study has shown the correlation of findings between the Rockwood tilt view and the arthroscopic finding. Methods: We developed the arthroscopic classification of acromion spur as type 1 flat spur, type 2 bump spur, type 3 heel spur, type 4 keel spur, and type 5 irregular spur. Patients with rotator cuff syndrome who underwent arthroscopic surgery were recruited. Two observers were asked to classify the type of spur from arthroscopic findings and Rockwood tilt views separately in random pattern. The prevalence of supraspinatus tendon tear was also recorded as no tear, partial-thickness tear, and full-thickness tear. Results: The keel spur (33.9% was the most common finding followed by the heel spur (27.8%. The correlation was high especially for the heel, the keel, and the irregular spur (75.47%, 74.03%, and 72.73%, respectively. These three types of spurs have a high prevalence of full thickness of supraspinatus tendon tear. Conclusion: The Rockwood tilt view can be used to evaluate the morphology of an acromion spur, especially the at-risk spur that correlates highly with the full-thickness supraspinatus tendon tear. The arthroscopic classification will also be a useful tool to improve communication between the surgeon and the guide for appropriate treatment in a rotator cuff tear patient when encountering the heel, keel, and irregular spur.

  18. Topological Edge States at a Tilt Boundary in Gated Multilayer Graphene

    OpenAIRE

    Abolhassan Vaezi; Yufeng Liang; Ngai, Darryl H.; Li Yang; Eun-Ah Kim

    2013-01-01

    Despite much interest in engineering new topological surface (edge) states using structural defects, such topological surface states have not been observed yet. We show that recently imaged tilt boundaries in gated multilayer graphene should support topologically protected gapless edge states. We approach the problem from two perspectives: the microscopic perspective of a tight-binding model and an ab initio calculation on a bilayer, and the symmetry-protected topological (SPT) state perspect...

  19. Six-implant-supported immediate fixed rehabilitation of atrophic edentulous maxillae with tilted distal implants.

    Science.gov (United States)

    Wentaschek, S; Hartmann, S; Walter, C; Wagner, W

    2017-12-01

    The aim of this retrospective study was to evaluate the treatment outcome of six Bredent blueSky™ implants (Bredent GmbH, Senden, Germany) immediately loaded with a fixed full-arch prosthesis (two tilted posterior and four axial frontal and premolar implants). All 10 patients with atrophic edentulous maxillae being treated with a standardized procedure from 09/2009 to 01/2013, who had a follow-up of at least 3 years, were included. Sixty implants were placed to support 10 screwed prostheses. Twenty-one of them were inserted in fresh extraction sockets. Lab-side-prepared provisional fixed prostheses were placed at the day of implantation. Periotest (PT) values and implant stability quotient (ISQ) were measured after implant surgery and after 3 months of healing in all patients. The analyzed implants were in function in mean 64 ± 13 months (range 42 to 84 months). One axial and two tilted implants failed in three patients. The mean PT values decreased, and ISQ increased significantly after the first 3 months at the osseointegrated tilted and axial implants. With an area under the curve of 0.503 and 0.506 in the receiver operating characteristic, the PT values and the ISQ were unspecific parameters and unsuitable as a predictor for the risk of non-osseointegration. Within the limits of this small group (n = 10 patients/60 implants), the failure rate of the analyzed implant system (n = 3 respective 5% implant loss) seems to be comparable with other immediate-loading protocols. The failure rate of tilted implants in the atrophic upper jaw was quite high, but the aimed treatment concept could be achieved in every patient. The rehabilitation of the posterior region in edentulous maxilla remains a challenge.

  20. A Semi-Empirical Model for Tilted-Gun Planar Magnetron Sputtering Accounting for Chimney Shadowing

    Science.gov (United States)

    Bunn, J. K.; Metting, C. J.; Hattrick-Simpers, J.

    2015-01-01

    Integrated computational materials engineering (ICME) approaches to composition and thickness profiles of sputtered thin-film samples are the key to expediting materials exploration for these materials. Here, an ICME-based semi-empirical approach to modeling the thickness of thin-film samples deposited via magnetron sputtering is developed. Using Yamamura's dimensionless differential angular sputtering yield and a measured deposition rate at a point in space for a single experimental condition, the model predicts the deposition profile from planar DC sputtering sources. The model includes corrections for off-center, tilted gun geometries as well as shadowing effects from gun chimneys used in most state-of-the-art sputtering systems. The modeling algorithm was validated by comparing its results with experimental deposition rates obtained from a sputtering system utilizing sources with a multi-piece chimney assembly that consists of a lower ground shield and a removable gas chimney. Simulations were performed for gun-tilts ranging from 0° to 31.3° from the vertical with and without the gas chimney installed. The results for the predicted and experimental angular dependence of the sputtering deposition rate were found to have an average magnitude of relative error of for a 0°-31.3° gun-tilt range without the gas chimney, and for a 17.7°-31.3° gun-tilt range with the gas chimney. The continuum nature of the model renders this approach reverse-optimizable, providing a rapid tool for assisting in the understanding of the synthesis-composition-property space of novel materials.

  1. Introducer Curving Technique for the Prevention of Tilting of Transfemoral Gunther Tulip Inferior Vena Cava Filter

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Liang; Shen, Jing; Tong, Jia Jie [The First Hospital of China Medical University, Shenyang (China); Huang, De Sheng [College of Basic Medical Science, China Medical University, Shenyang (China)

    2012-07-15

    To determine whether the introducer curving technique is useful in decreasing the degree of tilting of transfemoral Tulip filters. The study sample group consisted of 108 patients with deep vein thrombosis who were enrolled and planned to undergo thrombolysis, and who accepted transfemoral Tulip filter insertion procedure. The patients were randomly divided into Group C and Group T. The introducer curving technique was Adopted in Group T. The post-implantation filter tilting angle (ACF) was measured in an anteroposterior projection. The retrieval hook adhering to the vascular wall was measured via tangential cavogram during retrieval. The overall average ACF was 5.8 {+-} 4.14 degrees. In Group C, the average ACF was 7.1 {+-} 4.52 degrees. In Group T, the average ACF was 4.4 {+-} 3.20 degrees. The groups displayed a statistically significant difference (t = 3.573, p = 0.001) in ACF. Additionally, the difference of ACF between the left and right approaches turned out to be statistically significant (7.1 {+-} 4.59 vs. 5.1 {+-} 3.82, t = 2.301, p = 0.023). The proportion of severe tilt (ACF {>=} 10 degree) in Group T was significantly lower than that in Group C (9.3% vs. 24.1%, X{sup 2} = 4.267, p = 0.039). Between the groups, the difference in the rate of the retrieval hook adhering to the vascular wall was also statistically significant (2.9% vs. 24.2%, X{sup 2} = 5.030, p = 0.025). The introducer curving technique appears to minimize the incidence and extent of transfemoral Tulip filter tilting.

  2. Cardiovascular model for the simulation of exercise, lower body negative pressure, and tilt experiments

    Science.gov (United States)

    Croston, R. C.; Fitzjerrell, D. G.

    1974-01-01

    A mathematical model and digital computer simulation of the human cardiovascular system and its controls have been developed to simulate pulsatile dynamic responses to the cardiovascular experiments of the Skylab missions and to selected physiological stresses of manned space flight. Specific model simulations of the bicycle ergometry, lower body negative pressure, and tilt experiments have been developed and verified for 1-g response by comparison with available experimental data. The zero-g simulations of two Skylab experiments are discussed.

  3. The tilt-up osteotomy for correction of intractable plantar keratoses.

    Science.gov (United States)

    Berkun, R N; DeVincentis, A; Goller, W L

    1984-01-01

    The purpose of this paper is to describe and follow-up a new surgical technique used for the correction of intractable plantar keratoses. Twenty-five osteotomies were studied from 8 to 20 months postoperatively. The results showed a 60% success rate, but a patient satisfaction rate of 92%. The tilt-up osteotomy is a promising new procedure for the correction of intractable plantar keratoses.

  4. Morphological classification of acromial spur: correlation between Rockwood tilt view and arthroscopic finding

    Science.gov (United States)

    Kongmalai, Pinkawas; Apivatgaroon, Adinun; Chernchujit, Bancha

    2017-01-01

    Purpose and hypothesis: Acromion spur is the extrinsic factor for impingement syndrome and rotator cuff tear. The Rockwood tilt view can be used to evaluate prominence of the anterior acromion, however no study has shown the correlation of findings between the Rockwood tilt view and the arthroscopic finding. Methods: We developed the arthroscopic classification of acromion spur as type 1 flat spur, type 2 bump spur, type 3 heel spur, type 4 keel spur, and type 5 irregular spur. Patients with rotator cuff syndrome who underwent arthroscopic surgery were recruited. Two observers were asked to classify the type of spur from arthroscopic findings and Rockwood tilt views separately in random pattern. The prevalence of supraspinatus tendon tear was also recorded as no tear, partial-thickness tear, and full-thickness tear. Results: The keel spur (33.9%) was the most common finding followed by the heel spur (27.8%). The correlation was high especially for the heel, the keel, and the irregular spur (75.47%, 74.03%, and 72.73%, respectively.) These three types of spurs have a high prevalence of full thickness of supraspinatus tendon tear. Conclusion: The Rockwood tilt view can be used to evaluate the morphology of an acromion spur, especially the at-risk spur that correlates highly with the full-thickness supraspinatus tendon tear. The arthroscopic classification will also be a useful tool to improve communication between the surgeon and the guide for appropriate treatment in a rotator cuff tear patient when encountering the heel, keel, and irregular spur. PMID:28074776

  5. Towards an intelligent system for clinical guidance on wheelchair tilt and recline usage.

    Science.gov (United States)

    Fu, Jicheng; Wiechmann, Paul; Jan, Yih-Kuen; Jones, Maria

    2012-01-01

    We propose to construct an intelligent system for clinical guidance on how to effectively use power wheelchair tilt and recline functions. The motivations fall into the following two aspects. (1) People with spinal cord injury (SCI) are vulnerable to pressure ulcers. SCI can lead to structural and functional changes below the injury level that may predispose individuals to tissue breakdown. As a result, pressure ulcers can significantly affect the quality of life, including pain, infection, altered body image, and even mortality. (2) Clinically, wheelchair power seat function, i.e., tilt and recline, is recommended for relieving sitting-induced pressures. The goal is to increase skin blood flow for the ischemic soft tissues to avoid irreversible damage. Due to variations in the level and completeness of SCI, the effectiveness of using wheelchair tilt and recline to reduce pressure ulcer risks has considerable room for improvement. Our previous study indicated that the blood flow of people with SCI may respond very differently to wheelchair tilt and recline settings. In this study, we propose to use the artificial neural network (ANN) to predict how wheelchair power seat functions affect blood flow response to seating pressure. This is regression learning because the predicted outputs are numerical values. Besides the challenging nature of regression learning, ANN may suffer from the overfitting problem which, when occurring, leads to poor predictive quality (i.e., cannot generalize). We propose using the particle swarm optimization (PSO) algorithm to train ANN to mitigate the impact of overfitting so that ANN can make correct predictions on both existing and new data. Experimental results show that the proposed approach is promising to improve ANN's predictive quality for new data.

  6. Tilting at wave beams: a new perspective on the St. Andrew's Cross

    Science.gov (United States)

    Akylas, Triantaphyllos; Kataoka, Takeshi; Peacock, Thomas; Ghaemsaidi, Sasan; Holzenberger, Nils

    2017-04-01

    The generation of internal gravity waves by a vertically oscillating cylinder that is tilted to the horizontal in a uniformly stratified fluid of constant buoyancy frequency, is investigated. This variant of the widely-studied horizontal configuration-where a cylinder aligned horizontally with a plane of constant gravitational potential induces four wave beams forming a cross pattern known as St. Andrew's Cross-brings out certain unique features of radiated internal waves from a line source tilted to the horizontal. Specifically, for a given tilt of the cylinder, there is a cut-off frequency below which there is no longer a radiated wave field. Furthermore, three-dimensional effects due to the finite length of the cylinder, which are minor in the horizontal configuration, become a significant factor and eventually dominate the wave field as the cut-off frequency is approached. These results follow from simple kinematic analysis and are confirmed by supporting laboratory experiments. The kinematic analysis, moreover, suggests a resonance phenomenon near the cut-off frequency, where nonlinear and viscous effects are likely to play a part. This scenario is examined by an asymptotic model which predicts transfer of energy to a horizontal mean flow component. Experimental evidence of such an induced mean flow near cut-off is also presented.

  7. Influence of a tilted cavity on quantum-dot optoelectronic active devices

    Energy Technology Data Exchange (ETDEWEB)

    Liu Wanglai; Xu Bo; Liang Ping; Hu Ymg; Sun Hong; Lu Xueqin; Wang Zhanguo, E-mail: liuwanglai@semi.ac.c [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

    2009-09-15

    Quantum-dot laser diodes (QD-LDs) with a Fabry-Perot cavity and quantum-dot semiconductor optical amplifiers (QD-SOAs) with 7{sup 0} tilted cavity were fabricated. The influence of a tilted cavity on optoelectronic active devices was also investigated. For the QD-LD, high performance was observed at room temperature. The threshold current was below 30 mA and the slope efficiency was 0.36 W/A. In contrast, the threshold current of the QD-SOA approached 1000 mA, which indicated that low facet reflectivity was obtained due to the tilted cavity design. A much more inverted carrier population was found in the QD-SOA active region at high operating current, thus offering a large optical gain and preserving the advantages of quantum dots in optical amplification and processing applications. Due to the inhomogeneity and excited state transition of quantum dots, the full width at half maximum of the electroluminescence spectrum of the QD-SOA was 81.6 nm at the injection current of 120 mA, which was ideal for broad bandwidth application in a wavelength division multiplexing system. In addition, there was more than one lasing peak in the lasing spectra of both devices and the separation of these peak positions was 6-8 nm, which is approximately equal to the homogeneous broadening of quantum dots.

  8. [THE EFFECTS OF THE PILATES METHOD ON HAMSTRING EXTENSIBILITY, PELVIC TILT AND TRUNK FLEXION].

    Science.gov (United States)

    Vaquero-Cristóbal, Raquel; López-Miñarro, Pedro A; Alacid Cárceles, Fernando; Esparza-Ros, Francisco

    2015-11-01

    Pilates includes a high volume of hamstring stretching and maximal trunk flexion with knees extended exercises. to perform a systematic review about Pilates practice effects and a detraining period on hamstring extensibility, pelvic tilt and trunk flexion in maximal trunk flexion with knees extended. it was analysed all the experimental or quasi-experimental designs written in English, Spanish or Portuguese and included in the following databases: Pubmed, Sports Discus, ISI Web of Knowledge, Dialnet and Research Gate. twenty-one papers were analysed. Most of them used a pre-test-post-test design with control group. The intervention programs applied were heterogeneous. Samples were composed mainly of women, both young and old. It was found that the Pilates practice, with different volume, significantly increased hamstring muscle extensibility and pelvic tilt in maximal trunk flexion. At least three training sessions peer week during six weeks were necessary in order to obtain a high trunk inclination. Studies which involved athletes showed contradictory results. By inducing a detraining period it was noticed a decrease in hamstring extensibility and trunk flexion from the second week. there is a moderate evidence that Pilates is an effective method to increase hamstring extensibility, pelvic tilt and the degree of trunk flexion in maximal flexion positions in sedentary and recreational active people and also to increase hamstring extensibility in athletes. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

  9. Shared computational mechanism for tilt compensation accounts for biased verticality percepts in motion and pattern vision.

    Science.gov (United States)

    De Vrijer, M; Medendorp, W P; Van Gisbergen, J A M

    2008-02-01

    To determine the direction of object motion in external space, the brain must combine retinal motion signals and information about the orientation of the eyes in space. We assessed the accuracy of this process in eight laterally tilted subjects who aligned the motion direction of a random-dot pattern (30% coherence, moving at 6 degrees /s) with their perceived direction of gravity (motion vertical) in otherwise complete darkness. For comparison, we also tested the ability to align an adjustable visual line (12 degrees diameter) to the direction of gravity (line vertical). For small head tilts (60 degrees revealed a pattern of large systematic errors (often >30 degrees ) that was virtually identical in both tasks. Regression analysis confirmed that mean errors in the two tasks were closely related, with slopes close to 1.0 and correlations >0.89. Control experiments ruled out that motion settings were based on processing of individual single-dot paths. We conclude that the conversion of both motion direction and line orientation on the retina into a spatial frame of reference involves a shared computational strategy. Simulations with two spatial-orientation models suggest that the pattern of systematic errors may be the downside of an optimal strategy for dealing with imperfections in the tilt signal that is implemented before the reference-frame transformation.

  10. Evaluating solar radiation on a tilted surfaces - a study case in Timis (Romania)

    Science.gov (United States)

    Vasar, C.; Prostean, O.; Prostean, G.

    2016-02-01

    In the last years the usage of solar energy has grown considerably in Romania, as well as in Europe, stimulated by various factors as government programs, green pricing policies, decreasing of photovoltaic components cost etc. Also, the rising demand of using Solar Energy Conversion Systems (SECS) is driven by the desire of individuals or companies to obtain energy from a clean renewable source. In many applications, remote consumers far from other energetic grids can use solar systems more cost-effectively than extending the grid to reach the location. Usually the solar energy is measured or forecast on horizontal surface, but in SECS there is needed the total solar radiation incident on the collector surface, that is oriented in a position that maximize the harvested energy. There are many models that convert the solar radiation from horizontal surface to a tilted surface, but they use empirical coefficients and the accuracy is influenced by different facts as geographical location or sky conditions. Such models were used considering measured values for solar radiation on horizontal plane, in the western part of Romania. Hourly values measured for global solar irradiation on the horizontal plane, diffuse solar irradiation on the horizontal plane and reflected solar irradiation by ground are used to compute the total solar radiation incident on different tilted surfaces. The calculated incident radiation is then compared with the real radiation measured on tilted surface in order to evaluate the performance of the considered conversion models.

  11. Highly tilted liquid crystalline materials possessing a direct phase transition from antiferroelectric to isotropic phase

    Energy Technology Data Exchange (ETDEWEB)

    Milewska, K.; Drzewiński, W. [Institute of Chemistry, Military University of Technology, 00-908 Warsaw (Poland); Czerwiński, M., E-mail: mczerwinski@wat.edu.pl [Institute of Chemistry, Military University of Technology, 00-908 Warsaw (Poland); Dąbrowski, R. [Institute of Chemistry, Military University of Technology, 00-908 Warsaw (Poland); Piecek, W. [Institute of Applied Physics, Military University of Technology, 00-908 Warsaw (Poland)

    2016-03-01

    Pure compounds and multicomponent mixtures with a broad temperature range of high tilted liquid crystalline antiferroelectric phase and a direct phase transition from antiferroelectric to isotropic phase, were obtained. X-ray diffraction analysis confirms these kinds of materials form a high tilted anticlinic phase, with a fixed layer spacing and very weak dependency upon temperature, after the transition from the isotropic phase. Due to this, not only pure orthoconic antiferroelectric liquid crystals but also those with a moderate tilt should generate a good dark state. Furthermore, due to the increased potential for forming anticlinic forces, such materials could minimize a commonly observed asymmetry of a rise and fall switching times at a surface stabilized geometry. - Highlights: • The new class of liquid crystalline materials with the direct SmC{sub A}*. • Iso phase transition were obtained. • Materials possess the layer spacing fixed and very weak dependent upon temperature. • Smectic layers without shrinkage are observed. • A good dark state can be generate in SSAFLC.

  12. Implementation and evaluation of real-time pan-tilt-zoom camera calibration

    Science.gov (United States)

    Fung, Nicholas; David, Philip

    2008-08-01

    Pan-tilt-zoom (PTZ) cameras are frequently used in surveillance applications as they can observe a much larger region of the environment than a fixed-lens camera while still providing high-resolution imagery. The pan, tilt, and zoom parameters of a single camera may be simultaneously controlled by online users as well as automated surveillance applications. To accurately register autonomously tracked objects to a world model, the surveillance system requires accurate knowledge of camera parameters. Due to imprecision in the PTZ mechanism, these parameters cannot be obtained from PTZ control commands but must be calculated directly from camera imagery. This paper describes the efforts undertaken to implement a real-time calibration system for a stationary PTZ camera. The approach continuously tracks distinctive image feature points from frame to frame, and from these correspondences, robustly calculates the homography transformation between frames. Camera internal parameters are then calculated from these homographies. The calculations are performed by a self contained program that continually monitors images collected by the camera as it performs pan, tilt, and zoom operations. The accuracy of the calculated calibration parameters are compared to ground truth data. Problems encountered include inaccuracies in large orientation changes and long algorithm execution time.

  13. Influence of seat tilt motion on discomfort perception during a simulated driving activity.

    Science.gov (United States)

    Maradei, Fernanda; Quintana, Leonardo; Castellanos, Javier

    2017-01-01

    Discomfort perceived in activities where there is a prolonged sitting posture are normally compensated in a natural way by means of macro-repositioning movements in the seat. Nevertheless, evidence shows that such movements are not able to palliate discomfort due to lumbar pain. This study involves research performed to demonstrate whether induced postural changes are able to mitigate this type of discomfort during a simulated driving activity. Twenty-four subjects with lumbar pain (LBP) and without lumbar pain (WLBP) underwent 90 min of simulated driving activities while periodic variations of seat tilt (Tt) were implemented. Discomfort perception due to lumbar pain significantly decreased in the case of Tt compared with the case of WTt (without seat tilt), and significant differences were found (p = 0.02). However, treatments with Tt indicated that no substantial differences exist between LBP and WLBP subjects when considering discomfort perception due to lumbar pain and the erector spinae activity. This study revealed that periodic variations on seat tilt can help to reduce discomfort perception due to lumbar pain during driving activities, regardless of the health condition of the subject.

  14. Numerical simulations of a buoyant autocatalytic reaction front in tilted Hele-Shaw cells.

    Science.gov (United States)

    Jarrige, N; Bou Malham, I; Martin, J; Rakotomalala, N; Salin, D; Talon, L

    2010-06-01

    We present a numerical analysis of solutal buoyancy effects on the shape and the velocity of autocatalytic reaction fronts, propagating in thin tilted rectangular channels. We use two-dimensional (2D) lattice Bathnagar-Gross-Krook (BGK) numerical simulations of gap-averaged equations for the flow and the concentration, namely a Stokes-Darcy equation coupled with an advection-diffusion-reaction equation. We do observe stationary-shaped fronts, spanning the width of the cell and propagating along the cell axis. We show that the model accounts rather well for experiments we performed using an Iodate Arsenous Acid reaction propagating in tilted Hele-Shaw cells, hence validating our 2D modelization of a three-dimensional problem. This modelization is also able to account for results found for another chemical reaction (chlorite tetrathionate) in a horizontal cell. In particular, we show that the shape and the traveling velocity of such fronts are linked with an eikonal equation. Moreover, we show that the front velocity varies nonmonotonically with the tilt of the cell, and nonlinearly with the width of the cell.

  15. Topological defects at octahedral tilting plethora in bi-layered perovskites

    Science.gov (United States)

    Cheong, Sang-Wook; Huang, Fei-Ting; Cao, Bin; Kim, Jaewook; Luo, Xuan; Wang, Yazhong; Chu, Ming-Won; Chang, Ck; Shen, Hs

    Oxygen octahedral distortions including tilts/rotations, deformations and off-centering in (layered) perovskites play the key role in their numerous functional properties. Near the polar-centrosymmetric phase boundary in bi-layered perovskite Ca3-xSrxTi2O7 with x 1, we found the presence of abundant topological eight-state vortex-antivortex pairs, associated with four oxygen octahedral tilts at domains and another four different oxygen octahedral tilts at domain walls. The inter-relationship between this unique structural domain topology and magnetic domains with canted magnetic moments in related compounds will be presented. In addition, we will discuss the general topological classification scheme of the connectivity of domains and domain walls. The work at Rutgers University was supported by the Gordon and Betty Moore Foundation's EPiQS Initiative through Grant GBMF4413 to the Rutgers Center for Emergent Materials and the DOE under Grant No. DE-FG02-07ER46382.

  16. Validation of a new method for assessing scapular anterior-posterior tilt.

    Science.gov (United States)

    Scibek, Jason S; Carcia, Christopher R

    2014-10-01

    Electromagnetic tracking systems have enabled some investigators and clinicians to measure tri-planar scapular motion; yet, they are not practical and affordable options for all clinicians. Currently, the ability to affordably quantify scapular motion is limited to monitoring only the motion of scapular upward rotation, with use of a digital inclinometer. The objective of this study was to determine the criterion-related validity of a modified digital inclinometer when used to measure the motion of scapular anterior-posterior (AP) tilt. Thirteen volunteers, free from any history of shoulder injury, reported for a single testing session. Each subject underwent a brief shoulder and posture examination in order to confirm the absence of pathology. Subjects actively performed clinically relevant amounts of humeral elevation in the scapular plane while in a seated position. An electromagnetic tracking system (Ascension Technology, Burlington, VT) and a modified inclinometer (Pro 360, Baseline®, Fabrication Enterprises, White Plains, NY) were used to acquire scapular AP tilt over the same shoulder motions. Criterion-related validity was determined using Pearson Product Moment correlations. Correlation analyses revealed significant moderate to good associations (r = 0.63 to 0.86, p valid device to use for the quantification of scapular AP tilt. Further study is warranted to establish reliability and to validate use of the device in patients with shoulder injury or pathology. The modified inclinometer expands the clinician's ability to quantify scapular kinematic motion during the clinical evaluation and rehabilitation process. Level 3.

  17. Conductance modulation in Weyl semimetals with tilted energy dispersion without a band gap

    Science.gov (United States)

    Yesilyurt, Can; Siu, Zhuo Bin; Tan, Seng Ghee; Liang, Gengchiau; Jalil, Mansoor B. A.

    2017-06-01

    We investigate the tunneling conductance of Weyl semimetal with tilted energy dispersion by considering electron transmission through a p-n-p junction with one-dimensional electric and magnetic barriers. In the presence of both electric and magnetic barriers, we found that a large conductance gap can be produced with the aid of tilted energy dispersion without a band gap. The origin of this effect is the shift of the electron wave-vector at barrier boundaries caused by (i) the pseudo-magnetic field induced by electrical potential, i.e., a newly discovered feature that is only possible in the materials possessing tilted energy dispersion, (ii) the real magnetic field induced by a ferromagnetic layer deposited on the top of the system. We use a realistic barrier structure applicable in current nanotechnology and analyze the temperature dependence of the tunneling conductance. The new approach presented here may resolve a major problem of possible transistor applications in topological semimetals, i.e., the absence of normal backscattering and gapless band structure.

  18. MODELLING AND CONTROL OF H-SHAPED RACING QUADCOPTER WITH TILTING PROPELLERS

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    Ahmed Alkamachi

    2017-08-01

    Full Text Available Traditional quadcopter suffers terribly from its underactuation which implies the coupling between the rotational and the translational motion. In this paper, we present a quadcopter with dynamic rotor tilting capability in which the four propellers are allowed to tilt together around their arm axis. The proposed model provides leveled forward/backward horizontal motion and therefore, ensures a correct view of the onboard camera, and increases the vehicle speed by reducing the air drag. The rotor tilt mechanism also provides an instant high speed in the forward or reverse direction and offers a quick and solid air brake to restrain that fast moving speed.  The nonlinear dynamical model for the quadcopter under consideration is derived using Newton-Euler formalization. A control strategy is then proposed aimed to control the altitude, attitude, and the forward speed of the obtained model. Finally, a numerical simulation is used to integrate the system model with the controller and to test the system performance. Simulation results are reported to demonstrate the advantages of the proposed novel configuration.

  19. Directional Light Extinction and Emission in a Metasurface of Tilted Plasmonic Nanopillars.

    Science.gov (United States)

    Verre, R; Svedendahl, M; Odebo Länk, N; Yang, Z J; Zengin, G; Antosiewicz, T J; Käll, M

    2016-01-13

    Plasmonic optical antennas and metamaterials with an ability to boost light-matter interactions for particular incidence or emission angles could find widespread use in solar harvesting, biophotonics, and in improving photon source performance at optical frequencies. However, directional plasmonic structures have generally large footprints or require complicated geometries and costly nanofabrication technologies. Here, we present a directional metasurface realized by breaking the out-of-plane symmetry of its individual elements: tilted subwavelength plasmonic gold nanopillars. Directionality is caused by the complex charge oscillation induced in each individual nanopillar, which essentially acts as a tilted dipole above a dielectric interface. The metasurface is homogeneous over a macroscopic area and it is fabricated by a combination of facile colloidal lithography and off-normal metal deposition. Fluorescence excitation and emission from dye molecules deposited on the metasurface is enhanced in specific directions determined by the tilt angle of the nanopillars. We envisage that these directional metasurfaces can be used as cost-effective substrates for surface-enhanced spectroscopies and a variety of nanophotonic applications.

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

    Science.gov (United States)

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

    2000-01-01

    BACKGROUND: Exercise thermoregulation is dependent on heat loss by increased skin blood flow (convective and conductive heat loss) and through enhanced sweating (evaporative heat loss). Reduction of plasma volume (PV), increased plasma osmolality, physical deconditioning, and duration of exposure to simulated and actual microgravity reduces the ability to thermoregulate during exercise. HYPOTHESIS: We hypothesized that 24 h of head down tilt (HDT24) would alter thermoregulatory responses to a submaximal exercise test and result in a higher exercise rectal temperature (Tre) when compared with exercise Tre after 1 h of head down tilt (HDT1). METHODS: Seven men (31+/-SD 6 yr, peak oxygen uptake (VpO2peak) of 44+/-6 ml x kg(-1) x min(-1)) were studied during 70 min of supine cycling at 58+/-SE 1.5% VO2peak at 22.0 degrees C Tdb and 47% rh. RESULTS: Relative to pre-tilt sitting chair rest data, HDT1 resulted in a 6.1+/-0.9% increase and HDT24 in a 4.3+/-2.3% decrease in PV (delta = 10.4% between experiments, pthermoregulation), the Tre offset could have been caused by the HDT-induced hypovolemia.

  1. Effects of tilted angle of Bragg facets on the performance of successive strips based Bragg concave diffraction grating

    Science.gov (United States)

    Du, Bingzheng; Zhu, Jingping; Mao, Yuzheng; Wang, Kai; Chen, Huibing; Hou, Xun

    2018-03-01

    The effects of the tilted angle of facets on the diffraction orders, diffraction spectra, dispersion power, and the neighbor channel crosstalk of successive etching strips based Bragg concave diffraction grating (Bragg-CDG) are studied in this paper. The electric field distribution and diffraction spectra of four Bragg-CDGs with different tilted angles are calculated by numerical simulations. With the reflection condition of Bragg facets constant, the blazing order cannot change with the titled angle. As the tilted angle increases, the number of diffraction orders of Bragg-CDG will decrease, thereby concentrating more energy on the blazing order and improving the uniformity of diffraction spectra. In addition, the dispersion power of Bragg-CDG can be improved and the neighbor channel crosstalk of devices can be reduced by increasing the tilted angle. This work is beneficial to optimize the performance of Bragg-CDG.

  2. High-precision tilt sensor using a folded Mach-Zehnder geometry in-phase and quadrature interferometer.

    Science.gov (United States)

    Park, June Gyu; Cho, Kyuman

    2016-03-20

    A new high-sensitivity homodyne in-phase and quadrature (I/Q) -interferometer scheme for measuring the tilt change of a target is presented. The new tilt sensor is a Mach-Zehnder interferometer folded by the target, in which the phase change is induced by the in-plane tilt change of the target but is not sensitive to any other motions. The interferometer is specially designed to minimize interferences caused by environmental perturbations. The induced phase is directly measured by using the I/Q-demodulation scheme. The tilt sensor exhibits an excellent sensitivity 10  prad/Hz1/2 at a frequency slightly above 1 Hz and a 0.4  prad/Hz1/2 at a frequency higher than 30 Hz.

  3. Observing tilts in mid-crustal rocks by paleomagnetism, examples from southeast British Columbia

    Science.gov (United States)

    Marquis, Guy; Irving, E.

    1990-10-01

    Metamorphic core complexes that originated in the middle crust have been exposed by uplift and extension. Indicators of paleohorizontal planes are few or absent, thus it is difficult to determine the degree of tilting that might have accompanied this process. However, if aberrant paleomagnetic directions (paleodirections) are observed in core complexes or their associated intrusive rocks, and if large-scale rotation and translation can be excluded, then these paleodirections can be used to calculate the sense and magnitude of tilting. We describe paleodirections from mid-crustal rocks in southeastern British Columbia, where uplift and extension occurred in Eocene time about a central culmination aligned north-south. Several large extensional faults dip both to the west and to the east of this central culmination. The Eocene Granby pluton (49.3°N, 118.5°W), situated to the west of the main culmination, has a mean direction of magnetization (D°, I°) 309°, 41° (α63° = 7° the standard error) and paleopole at 44°N, 138°E (A63° = 7°). To the east of the main culmination, a 20 km long section of altered Eocene Syringa dikes and associated metadiorite (49.3°N, 117.7°W) has a mean direction of 56°, 47° (α63° = 3°) and paleopole at 56°N, 319°E (A63° = 3°). The paleopoles are very different from one another, and from those calculated from contemporaneous (53 to 49 Ma) rocks of the North American craton to the east. They also differ from those observed from coeval bedded volcanic rocks to the west of the sampling area. Hence, these large aberrancies cannot be caused by translations. We suggest that they are caused by tilting which occurred during the extension process. The tilts are in opposite senses on either side of the central culmination. They are estimated to be down 38°±8° at 99°E for the Granby Pluton, and down 41°±4° at 270°W for the dikes and metadiorite. These tilts are consistent with the Wernicke model for simple extensional shear.

  4. Remote sensing of a NTC radio source from a Cluster tilted spacecraft pair

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    P. M. E. Décréau

    2013-11-01

    Full Text Available The Cluster mission operated a "tilt campaign" during the month of May 2008. Two of the four identical Cluster spacecraft were placed at a close distance (~50 km from each other and the spin axis of one of the spacecraft pair was tilted by an angle of ~46°. This gave the opportunity, for the first time in space, to measure global characteristics of AC electric field, at the sensitivity available with long boom (88 m antennas, simultaneously from the specific configuration of the tilted pair of satellites and from the available base of three satellites placed at a large characteristic separation (~1 RE. This paper describes how global characteristics of radio waves, in this case the configuration of the electric field polarization ellipse in 3-D-space, are identified from in situ measurements of spin modulation features by the tilted pair, validating a novel experimental concept. In the event selected for analysis, non-thermal continuum (NTC waves in the 15–25 kHz frequency range are observed from the Cluster constellation placed above the polar cap. The observed intensity variations with spin angle are those of plane waves, with an electric field polarization close to circular, at an ellipticity ratio e = 0.87. We derive the source position in 3-D by two different methods. The first one uses ray path orientation (measured by the tilted pair combined with spectral signature of magnetic field magnitude at source. The second one is obtained via triangulation from the three spacecraft baseline, using estimation of directivity angles under assumption of circular polarization. The two results are not compatible, placing sources widely apart. We present a general study of the level of systematic errors due to the assumption of circular polarization, linked to the second approach, and show how this approach can lead to poor triangulation and wrong source positioning. The estimation derived from the first method places the NTC source region in the

  5. Improved tilt sensing in an LGS-based tomographic AO system based on instantaneous PSF estimation

    Science.gov (United States)

    Veran, Jean-Pierre

    2013-12-01

    Laser guide star (LGS)-based tomographic AO systems, such as Multi-Conjugate AO (MCAO), Multi-Object AO (MOAO) and Laser Tomography AO (LTAO), require natural guide stars (NGSs) to sense tip-tilt (TT) and possibly other low order modes, to get rid of the LGS-tilt indetermination problem. For example, NFIRAOS, the first-light facility MCAO system for the Thirty Meter Telescope requires three NGSs, in addition to six LGSs: two to measure TT and one to measure TT and defocus. In order to improve sky coverage, these NGSs are selected in a so-called technical field (2 arcmin in diameter for NFIRAOS), which is much larger than the on-axis science field (17x17 arcsec for NFIRAOS), on which the AO correction is optimized. Most times, the NGSs are far off-axis and thus poorly corrected by the high-order AO loop, resulting in spots with low contrast and high speckle noise. Accurately finding the position of such spots is difficult, even with advanced methods such as matched-filtering or correlation, because these methods rely on the knowledge of an average spot image, which is quite different from the instantaneous spot image, especially in case of poor correction. This results in poor tilt estimation, which, ultimately, impacts sky coverage. We propose to improve the estimation of the position of the NGS spots by using, for each frame, a current estimate of the instantaneous spot profile instead of an average profile. This estimate can be readily obtained by tracing wavefront errors in the direction of the NGS through the turbulence volume. The latter is already computed by the tomographic process from the LGS measurements as part of the high order AO loop. Computing such a wavefront estimate has actually already been proposed for the purpose of driving a deformable mirror (DM) in each NGS WFS, to optically correct the NGS spot, which does lead to improved centroiding accuracy. Our approach, however, is much simpler, because it does not require the complication of extra DMs

  6. Defining Optimal Head-Tilt Position of Resuscitation in Neonates and Young Infants Using Magnetic Resonance Imaging Data.

    Directory of Open Access Journals (Sweden)

    Utpal S Bhalala

    Full Text Available Head-tilt maneuver assists with achieving airway patency during resuscitation. However, the relationship between angle of head-tilt and airway patency has not been defined. Our objective was to define an optimal head-tilt position for airway patency in neonates (age: 0-28 days and young infants (age: 29 days-4 months. We performed a retrospective study of head and neck magnetic resonance imaging (MRI of neonates and infants to define the angle of head-tilt for airway patency. We excluded those with an artificial airway or an airway malformation. We defined head-tilt angle a priori as the angle between occipito-ophisthion line and ophisthion-C7 spinous process line on the sagittal MR images. We evaluated medical records for Hypoxic Ischemic Encephalopathy (HIE and exposure to sedation during MRI. We analyzed MRI of head and neck regions of 63 children (53 neonates and 10 young infants. Of these 63 children, 17 had evidence of airway obstruction and 46 had a patent airway on MRI. Also, 16/63 had underlying HIE and 47/63 newborn infants had exposure to sedative medications during MRI. In spontaneously breathing and neurologically depressed newborn infants, the head-tilt angle (median ± SD associated with patent airway (125.3° ± 11.9° was significantly different from that of blocked airway (108.2° ± 17.1° (Mann Whitney U-test, p = 0.0045. The logistic regression analysis showed that the proportion of patent airways progressively increased with an increasing head-tilt angle, with > 95% probability of a patent airway at head-tilt angle 144-150°.

  7. Defining Optimal Head-Tilt Position of Resuscitation in Neonates and Young Infants Using Magnetic Resonance Imaging Data.

    Science.gov (United States)

    Bhalala, Utpal S; Hemani, Malvi; Shah, Meehir; Kim, Barbara; Gu, Brian; Cruz, Angelo; Arunachalam, Priya; Tian, Elli; Yu, Christine; Punnoose, Joshua; Chen, Steven; Petrillo, Christopher; Brown, Alisa; Munoz, Karina; Kitchen, Grant; Lam, Taylor; Bosemani, Thangamadhan; Huisman, Thierry A G M; Allen, Robert H; Acharya, Soumyadipta

    2016-01-01

    Head-tilt maneuver assists with achieving airway patency during resuscitation. However, the relationship between angle of head-tilt and airway patency has not been defined. Our objective was to define an optimal head-tilt position for airway patency in neonates (age: 0-28 days) and young infants (age: 29 days-4 months). We performed a retrospective study of head and neck magnetic resonance imaging (MRI) of neonates and infants to define the angle of head-tilt for airway patency. We excluded those with an artificial airway or an airway malformation. We defined head-tilt angle a priori as the angle between occipito-ophisthion line and ophisthion-C7 spinous process line on the sagittal MR images. We evaluated medical records for Hypoxic Ischemic Encephalopathy (HIE) and exposure to sedation during MRI. We analyzed MRI of head and neck regions of 63 children (53 neonates and 10 young infants). Of these 63 children, 17 had evidence of airway obstruction and 46 had a patent airway on MRI. Also, 16/63 had underlying HIE and 47/63 newborn infants had exposure to sedative medications during MRI. In spontaneously breathing and neurologically depressed newborn infants, the head-tilt angle (median ± SD) associated with patent airway (125.3° ± 11.9°) was significantly different from that of blocked airway (108.2° ± 17.1°) (Mann Whitney U-test, p = 0.0045). The logistic regression analysis showed that the proportion of patent airways progressively increased with an increasing head-tilt angle, with > 95% probability of a patent airway at head-tilt angle 144-150°.

  8. Assessment of triangle tilt surgery in children with obstetric brachial plexus injury using the pediatric outcomes data collection instrument.

    Science.gov (United States)

    Nath, Rahul K; Avila, Meera B; Karicherla, Priyanka; Somasundaram, Chandra

    2011-01-01

    The benefits of triangle tilt surgery in children with OBPI have been previously validated through measurements of statistical improvements in Mallet scores and in glenohumeral congruity. The purpose of the current study was to evaluate the effectiveness of triangle tilt surgery through the application of the Pediatric Outcomes Data Collection Instrument, a well validated questionnaire designed to evaluate function and comfort in children with musculoskeletal disorders. OBPI patients between 2 and 10 years of age who came to our institute for routine office visits between May 2009 and October 2009 were considered to participate in the study. Among the patient group, the first 130 completed surveys who met the study criteria were included in the study. The Pediatric Outcomes Data Collection Instrument was completed by the parents of patients who have undergone triangle tilt surgery (Group 1: N=63) or those who were considered candidates for this procedure (Group 2: N=67). The results were compared between the two patient groups and analyzed using the unpaired student's t-test. Later, 23 patients from the group 2, underwent triangle tilt surgery (Group 3). We collected post-op data, compared and analyzed the outcome of the surgery in these patients to their own pre-op PODCI scores, using the paired student's t test. In patients who have undergone triangle tilt surgery, significantly higher PODCI scores were observed in the parameters of upper extremity function (ptriangle tilt surgery. Further, PODCI scores in group 3 patients were significantly higher after surgery in the parameters of upper extremity function (p triangle tilt surgery. The results of the Pediatric Outcomes Data Collection Instrument demonstrate the functional benefits of triangle tilt surgery in patients with obstetric brachial plexus injury.

  9. Active correction of the tilt angle of the surface plane with respect to the rotation axis during azimuthal scan

    Science.gov (United States)

    Sereno, M.; Lupone, S.; Debiossac, M.; Kalashnyk, N.; Roncin, P.

    2016-09-01

    A procedure to measure the residual tilt angle τ between a flat surface and the azimuthal rotation axis of the sample holder is described. When the incidence angle θ and readout of the azimuthal angle ϕ are controlled by motors, an active compensation mechanism can be implemented to reduce the effect of the tilt angle during azimuthal motion. After this correction, the effective angle of incidence is kept fixed, and only a small residual oscillation of the scattering plane remains.

  10. Mathematical Model and Analysis of the Water-Lubricated Hydrostatic Journal Bearings considering the Translational and Tilting Motions

    Directory of Open Access Journals (Sweden)

    Hui-Hui Feng

    2014-01-01

    Full Text Available The water-lubricated bearings have been paid attention for their advantages to reduce the power loss and temperature rise and increase load capacity at high speed. To fully study the complete dynamic coefficients of two water-lubricated, hydrostatic journal bearings used to support a rigid rotor, a four-degree-of-freedom model considering the translational and tilting motion is presented. The effects of tilting ratio, rotary speed, and eccentricity ratio on the static and dynamic performances of the bearings are investigated. The bulk turbulent Reynolds equation is adopted. The finite difference method and a linear perturbation method are used to calculate the zeroth- and first-order pressure fields to obtain the static and dynamic coefficients. The results suggest that when the tilting ratio is smaller than 0.4 or the eccentricity ratio is smaller than 0.1, the static and dynamic characteristics are relatively insensitive to the tilting and eccentricity ratios; however, for larger tilting or eccentricity ratios, the tilting and eccentric effects should be fully considered. Meanwhile, the rotary speed significantly affects the performance of the hydrostatic, water-lubricated bearings.

  11. A study of tilt change recorded from July to October 2006 at the Phlegraean Fields (Naples, Italy

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    C. Del Gaudio

    2007-06-01

    Full Text Available The tiltmetric dataset of Phlegraean Fields area showed a discrete correlation with the volcanic dynamics, suggesting that tiltmetric monitoring is important for the surveillance of active volcanic areas. Tilt data recorded in 2006 at 2 stations belonging to the monitoring network of the Osservatorio Vesuviano (INGV, National Institute for Geophysics and Volcanology, Italy in the Phlegraean Fields are discussed in this paper. The acquired signals have shown a strong tiltmetric inversion that took place from the end of July 2006. After correcting tilt variations to eliminate the influence of temperature (influencing 90% of the signal at OLB station, hereafter OLB a significant value of the tilt still remains. This change is related to a local inflation episode lasting 3 months, during an unrest phase that started 2 years before. It is interesting to note that tilt amplitude is much greater at OLB than the slope of the displacement field predicted by the theoretical inflation models, but data show that this field is not homogeneous and in some areas very tilted. Moreover, in the last days before the end of tilt inversion, a low energy seismic swarm happened at about 1 km of distance from the tiltmetric station by hundreds of VT (Volcano-Tectonics and LP (Long-Period events.

  12. Coherent tilt signals observed in the Shumagin seismic gap Detection of time-dependent subduction at depth?

    Science.gov (United States)

    Beavan, J.; Bilham, R.; Hurst, K.

    1984-01-01

    Repeated surveys of short level lines in the Shumagin Islands, Alaska, reveal coherent tilt signals associated with subduction of the Pacific plate beneath the North American plate in the Shumagin seismic gap. Ten years of steady tilt down toward the trench is interrupted during 1978-1980 by a rapid episode of reverse tilt. The 'normal' tilt represents surface deformation as subduction occurs, with the plate boundary locked to at least 60 km depth. Using all available tilt, sea level, and seismic data, the tilt reversal is interpreted as due to an episodic reverse slip of about 80 cm magnitude on the plate boundary between about 70 km and 20 km depth, downdip from the main seismogenic zone, which remains locked. This event causes an increase of stress on the locked main thrust zone. It is speculated that such events may be a regular process at subduction zones, that great plate boundary earthquakes may be more common during their occurrence, and that their onset may be detectable early enough to give warning of an increase in probability for the occurrence of a great earthquake.

  13. Quasi-Biennial Oscillation in Phase Speed, Vertical Tilting, and Form Stress of Equatorial Waves in the Stratosphere

    Science.gov (United States)

    Barton, C.; Cai, M.; Shin, C.

    2013-12-01

    We have diagnosed phase speed, wave tilt, and form drag of atmospheric waves in the equatorial stratosphere using daily fields in the NCEP-NCAR II reanalysis dataset. The time series of phase speed, wave tilt, and form drag, or pressure torque, are studied with respect to the tropical stratospheric quasi-biennial oscillation (QBO) of mean zonal winds. Observed (ground-relative) phase speed values are found to oscillate quasi-biennially such that ground-relative phase speed increases during the local easterly QBO phase and decreases during the local westerly QBO phase. The wave is found to tilt westward during the local westerly phase and eastward during the local easterly phase. Such QBO oscillation of wave tilting is consistent with the well-known fact that Kelvin and mixed Rossby-gravity waves are dominant in the local easterly and westerly phase, respectively. The eastward tilting waves have positive pressure torque, acting to transfer easterly angular momentum downward, while westward tilting waves have negative pressure torque, transferring westerly angular momentum downward during the local westerly phase.

  14. Head Tilt

    Science.gov (United States)

    ... Ear Nose & Throat Emotional Problems Eyes Fever From Insects or Animals Genitals and Urinary Tract Glands & Growth ... can be due to other causes such as hearing loss, misalignment of the eyes, reflux (a flowing ...

  15. Octahedral tilt transitions in the relaxor ferroelectric Na{sub 1/2}Bi{sub 1/2}TiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Kai-Christian, E-mail: meyer@mm.tu-darmstadt.de; Gröting, Melanie; Albe, Karsten

    2015-07-15

    The kinetics of octahedral tilt transitions in the lead-free relaxor material sodium bismuth titanate Na{sub 1/2}Bi{sub 1/2}TiO{sub 3} (NBT) is investigated by electronic structure calculations within density functional theory. Energy barriers for transitions between tetragonal, rhombohedral and orthorhombic tilts in cation configurations with [001]- and [111]-order on the A-sites are determined by nudged elastic band calculations. By tilting entire layers of octahedra simultaneously we find that the activation energy is lower for structures with 001-order compared to such with 111-order. The energetic coupling between differently tilted layers is, however, negligibly small. By introducing a single octahedral defect we create local tilt disorder and find that the deformation energy of the neighboring octahedra is less in a rhombohedral than in a tetragonal structure. By successively increasing the size of clusters of orthorhombic defects in a rhombohedral matrix with 001-order, we determine a critical cluster size of about 40 Å . Thus groups of about ten octahedra can be considered as nuclei for polar nanoregions, which are the cause of the experimentally observed relaxor behavior of NBT. - Graphical abstract: Nine orthorhombic oxygen octahedral tilt defects in a rhombohedral tilt configuration. - Highlights: • Chemical order influences energy barriers of octahedral tilt transitions. • The octahedral deformation energy is lower in rhombohedral phases. • Tilt defect clusters are more likely in rhombohedral structures. • Tilt defect clusters can act as nuclei for polar nanoregions.

  16. Atomic structures of symmetric tilt grain boundaries in hexagonal close packed (hcp) crystals

    Science.gov (United States)

    Wang, J.; Beyerlein, I. J.

    2012-03-01

    Using molecular dynamics (MD) simulations, the dislocation structures of [1 \\bar {2} 1 0] symmetric tilt grain boundaries (STGBs) in hexagonal close packed (hcp) crystal structures are studied. STGBs over the entire range of possible rotation angles θ from 0° to 90° are found to have an ordered atomic structure. Formation energy calculations reveal four local minimum-energy boundaries that correspond to coherent grain boundaries (GBs). Deviations in tilt from the basal plane (θ = 0°, P_B(1) ) , prismatic plane (θ = 90°, P_B(6) ) , or one of these four minimum-energy boundaries, P_B(2) ,P_B(3) ,P_B(4) ,P_B(5) , result in the formation of a tilt wall (edge-type grain boundary dislocations, GBDs) superimposed on the nearest GB structure P_B(i) in θ-space. As θ deviates far from the rotation angle of one P_B(i) and draws closer to that of an adjacent P_B(j) , an abrupt transition in STGB base boundary structure and GBD Burgers vector occurs. For all θ, the sign and spacing of GBDs depend on θ, and their Burgers vector is either one or two times the interplanar spacing of PB. We present a simple model that generalizes the results to other c/a ratios. Subsequent MD simulations show that (1) the model forecasts the STGB structure to first-order and (2) STGBs with two distinct atomic structures can have remarkably different responses when interacting with basal lattice dislocations originating from the adjoining crystals.

  17. Continuing the investigation to tilting Uranus with a secular spin-orbit resonance

    Science.gov (United States)

    Rogoszinski, Zeeve; Hamilton, Douglas P.

    2017-10-01

    The most accepted hypothesis for the origin of Uranus’ 98° obliquity is one or more giant collisions during the late stages of planetary formation. Morbidelli et al. (2012) argue that two collisions are needed to explain Uranus' satellites' prograde orbits. While this model is plausible, it does require impactors of at least 0.3-1 Earth masses, depending on the quantity, to strike close to Uranus’ pole and induce a tilting. Even larger mass impactors would be required for more equatorial collisions. Here we explore an alternative non-collision model to titling Uranus by using a secular spin-orbit resonance between Uranus and Neptune during the earlier stages of planetary formation. The inspiration for this model comes from a similar explanation of Saturn’s non-negligible tilt, where a secular resonance between Saturn’s spin axis and Neptune’s orbital pole is responsible (Ward and Hamilton (2004) & Hamilton and Ward (2004)). 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. The magnitude of this effect, however, may not be sufficient to drive Uranus all the way to its current obliquity. A resonant kick, where the speed of the migrating planet is near the adiabatic limit, can tilt Uranus up to 40° in a reasonable timespan, and so could replace one of the impactors required in the collisional scenario of Morbidelli et al. (2012). In most situations, however, the effect of such a resonant kick is only of order 10°. We are now considering various hybrid models that involve resonant captures and kicks as in Hamilton and Ward (2004), collisions and captures, and collisions and kicks, and will report on our findings.

  18. Effect of polymer concentration on stabilized large-tilt-angle flexoelectro-optic switching

    Science.gov (United States)

    Broughton, B. J.; Clarke, M. J.; Morris, S. M.; Blatch, A. E.; Coles, H. J.

    2006-01-01

    In this letter, the uniform lying helix (ULH) liquid crystal texture, required for the flexoelectro-optic effect, is polymer stabilized by the addition of a small percentage of reactive mesogen to a high-tilt-angle (φ>60°) bimesogenic chiral nematic host. The electro-optic response is measured for a range of reactive mesogen concentration mixtures, and compared to the large-tilt-angle switch of the pure chiral nematic mixture. The optimum concentration of reactive mesogen, which is found to provide ample stabilization of the texture with minimal impact on the electro-optic response, is found to be approximately 3%. Our results indicate that polymer stabilization of the ULH texture using a very low concentration of reactive mesogen is a reliable way of ruggedizing flexoelectro-optic devices without interfering significantly with the electro-optics of the effect, negating the need for complicated surface alignment patterns or surface-only polymerization. The polymer stabilization is shown to reduce the temperature dependence of the flexoelectro-optic response due to ``pinning'' of the chiral nematic helical pitch. This is a restriction of the characteristic thermochromic behavior of the chiral nematic. Furthermore, selection of the temperature at which the sample is ultraviolet cured allows the tilt angle to be optimized for the entire chiral nematic temperature range. The response time, however, remains more sensitive to operating temperature than curing temperature. This allows the sample to be cured at low temperature and operated at high temperature, providing simultaneous optimization of these two previously antagonistic performance aspects.

  19. The distribution of tilt angles in newly born NSs: role of interior viscosity and magnetic field

    Science.gov (United States)

    Dall'Osso, Simone; Perna, Rosalba

    2017-12-01

    We study how the viscosity of neutron star (NS) matter affects the distribution of tilt angles (χ) between the spin and magnetic axes in young pulsars. Under the hypothesis that the NS shape is determined by the magnetically induced deformation, and that the toroidal component of the internal magnetic field exceeds the poloidal one, we show that the dissipation of precessional motions by bulk viscosity can naturally produce a bi-modal distribution of tilt angles, as observed in radio/γ-ray pulsars, with a low probability of achieving χ ˜ (20°-70°) if the interior B-field is ˜(1011-1015) G and the birth spin period is ˜10-300 ms. As a corollary of the model, the idea that the NS shape is solely determined by the poloidal magnetic field, or by the centrifugal deformation of the crust, is found to be inconsistent with the tilt angle distribution in young pulsars. When applied to the Crab pulsar, with χ ˜ 45°-70° and birth spin ≳20 ms, our model implies that: (I) the magnetically induced ellipticity is ɛB ≳ 3 × 10-6; and (II) the measured positive\\dot{χ } ˜ 3.6 × 10^{-12} rad s-1 requires an additional viscous process, acting on a time-scale ≲104 yr. We interpret the latter as crust-core coupling via mutual friction in the superfluid NS interior. One critical implication of our model is a gravitational wave signal at (twice) the spin frequency of the NS. For ɛB ˜ 10-6, this could be detectable by Advanced LIGO/Virgo operating at design sensitivity.

  20. Influence of windshield tint and tilt on recognition distance under mesopic conditions.

    Science.gov (United States)

    Waetjen, R; Schiefer, U; Gaigl, A; Aulhorn, E

    1992-01-01

    The influence of the angle of inclination and tint of windshields on recognition distance was tested in 94 subjects aged 20-83 years. Both clear and tinted (heat-absorbing) windshields were tested. Light transmission (in the vertical position) was 90.3% for the clear windshield and 81.0% for the tinted windshield. The windshields could be set at angles of 0 degree (vertical), 30 degrees, 50 degrees and 70 degrees of inclination. The tests were performed at night with low-beam headlights (mesopic conditions). A Landolt ring (diameter 43.5 cm; contrast 1:1.5) served as a test stimulus; it was painted on a disc 87 cm in diameter that could be rotated in steps of 45 degrees. The mean recognition distance without the windshield was 32.2 m +/- 5.5 m (mean +/- SD). It decreased to 31.0 m +/- 5.6 m (29.0 m +/- 5.3 m) by using a clear windshield in the vertical position (values for the tinted windshield are shown in parentheses): 30.1 m +/- 5.6 m (27.9 m +/- 5.3 m) with a 50 degrees angle of tilt, and 28.5 m +/- 5.4 m (26.9 m +/- 5.1 m) with a 70 degrees angle. The differences between the recognition distances obtained using the various tilts and tints were small but statistically significant (P < 0.01 in all cases: Student's paired t-test). Since the performance of the human eye is stressed to its limits during nighttime driving, our study suggests that extreme tilt of the windshield should be avoided and that the option of delivering cars equipped with a heat-absorbing but clear front windshield should be provided.