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Sample records for included head tilt

  1. Head Tilt

    Science.gov (United States)

    ... bones in the neck. Children with Klippel-Feil syndrome may have a short, broad neck, low hairline, and very restricted neck movement. Torticollis ... surgery may be necessary. To treat Klippel-Feil syndrome, a specialist may recommend ... to ease head and neck pain. Your pediatrician can refer you to a ...

  2. Unilateral otolith centrifugation by head tilt.

    Science.gov (United States)

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

    2014-01-01

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

  3. 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.

  4. 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...

  5. Unilateral otolith centrifugation by head tilt

    NARCIS (Netherlands)

    Winters, S.M.; Bos, J.E.; Klis, S.F.L.

    2014-01-01

    BACKGROUND: To test for otolith asymmetries, several studies described horizontal translation of the body and head en bloc during fast vertical axis rotation. This stimulus causes one otolithic organ to rotate on-axis, and the other to experience centripetal acceleration. OBJECTIVE: To test a new,

  6. The impact of gravity during head-up tilt

    DEFF Research Database (Denmark)

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

    2011-01-01

    and the carotid sinuses in a healthy volunteer. During head-up tilt the head is lifted above the heart stimulating gravitational pooling of blood in the lower extremities. This shift in volume is followed by an increase in blood pressure in the lower body, while the pressure in the head decreases, while...... a model predicting hydrostatic height between the two locations. Results from this model were compared with measurements. Furthermore, we show, using a differential equations model predicting blood pressure, that it is possible to predict blood pressure measured at the level of the carotid sinuses using...

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

    Science.gov (United States)

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

    1992-01-01

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

  8. A patient treated with tilt training and midodrine after 68 seconds asystole during head-up tilt table testing.

    Science.gov (United States)

    Oz, Fahrettin; Cizgici, Yaşar; Bilge, A Kaya

    2011-08-01

    Neurocardiogenic syncope is a relatively common cause of syncope and is diagnosed by head-up tilt testing. A 21-year-old man was examined for frequent syncope episodes which occurred after episodes of blood drawing and standing in queue. Syncope developed in tilt table testing. After about 68 seconds, sinus rhythm returned. Recent reports have shown that tilt training is a very effective therapy for recurrent neurocardiogenic syncope. In our case, the patient was treated with midodrine 2.5 mg once a day and a tilt training programme. Therapy resulted in improvement and during a follow-up of six months, no major events occurred.

  9. SPECT imaging: Experimental determination of the effect of camera head tilt and appropriate quality control protocol

    International Nuclear Information System (INIS)

    Farrell, T.J.; Cradduck, T.D.

    1985-01-01

    Although it is recognized in SPECT imaging that the camera face shall remain parallel to the axis of rotation there is no evidence of the limits that must be imposed on this parameter for acceptable reconstruction of the data. This study was made with the purpose of establishing limits of camera head tilt based on experiments designed to measure degradation of the image with increasing camera head tilt. The effect of camera head tilt is to place off-axis data in the wrong plane for reconstruction. Points off axis exhibit a pseudomotion along a line parallel to the axis of rotation so that data from one plane are ''seen'' by the reconstruction algorithm to be in different planes, depending on the angle of rotation. The changes in system resolution due to camera head tilt were assessed using the cold spheres in a Jaszczak phantom. The contrast of the spheres was measured for increasing angles of head tilt. Significant degradation occurred at tilt angles as low as one degree. Based on these observations a quality control procedure for camera head tilt was developed. A point source is imaged off-axis and a computer program has been written that is able to give the angle of head tilt based on the pseudomotion of the point source throughout the rotation of the camera head. This method can be used to calibrate the head tilt angle. It is evident that the camera head tilt must be checked for every patient study. Unlike center of rotation offsets, it is not possible to correct the raw data for camera head tilt during reconstruction

  10. Rat cardiovascular responses to whole body suspension - Head-down and non-head-down tilt

    Science.gov (United States)

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

    1992-01-01

    Two experiments aimed at examining the versatility of the whole body suspension (WBS) system as a ground-based model for cardiovascular effects of microgravity are described. The first experiment studied heart rate and arterial pressure responses in rats during a 7-day period of head-down tilt (HDT) or nonhead-down tilt (NHDT) and after removal from whole body suspension (WBS). Mean arterial (MAP), systolic, and diastolic pressures increased about 20 percent in HDT rats on the fist day, heart rates were elevated about 10 percent. During postsuspension most cardiovascular parameters returned to presuspension levels. The second experiment evaluated responses to rapid head-up tilt in HDT and NHDT rats. It was observed that, while pulse pressures remained unchanged, MAP, systolic and diastolic pressures, and HR were elevated in HDT and NHDT rats during head-up tilt after one day of suspension. The WBS rats are considered to be useful as a model to better understand responses of rats exposed to microgravity.

  11. Patient Specific Modeling of Head-Up Tilt

    DEFF Research Database (Denmark)

    Williams, Nakeya; Wright, Andrew; Mehlsen, Jesper

    2014-01-01

    blood pressure. The model contains five compartments representing arteries and veins in the upper and lower body of the systemic circulation, as well as the left ventricle facilitating pumping of the heart. A physiologically based sub-model describes gravitational effects on pooling of blood during......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...... that it is possible to estimate a subset of model parameters that allows prediction of observed changes in arterial blood pressure. Furthermore, the model adequately predicts arterial and venous blood pressures, as well as cardiac output in compartments for which data are not available....

  12. The sensitivity of the bielschowsky head-tilt test in diagnosing acquired bilateral superior oblique paresis.

    Science.gov (United States)

    Muthusamy, Brinda; Irsch, Kristina; Peggy Chang, Han-Ying; Guyton, David L

    2014-04-01

    To determine the sensitivity of the Bielschowsky head-tilt test and other commonly used criteria in identifying patients with true bilateral superior oblique paresis. A retrospective chart review was performed to identify patients seen between 1978 and 2009 who were diagnosed with acquired bilateral superior oblique paresis. All patients had a confirmed history of head trauma or brain surgery with altered consciousness followed by symptomatic diplopia. Bilateral superior oblique paresis was defined and diagnosed by the above history, including the presence of greater extorsion in downgaze than upgaze on Lancaster red-green testing, a V-pattern strabismus, and bilateral fundus extorsion. We analyzed findings of the Bielschowsky head-tilt test, the Parks 3-step test, and reversal of the hypertropia from straight-ahead gaze to the other 8 diagnostic positions of gaze to determine these tests' sensitivity in identifying true bilateral superior oblique paresis. Twenty-five patients were identified with the diagnosis of true bilateral superior oblique paresis. The Bielschowsky head-tilt test had a 40% sensitivity, the Parks 3-step test had a sensitivity of 24%, and reversal of the hypertropia had a sensitivity of 60% in making the diagnosis of true bilateral superior oblique paresis. What previously has been described as masked bilateral superior oblique paresis simply may be a reflection of inherent poor sensitivity of the Bielschowsky head-tilt test, the Parks 3-step test, and reversal of the hypertropia in diagnosing bilateral superior oblique paresis. Hence, none of these tests should be relied on exclusively to make this diagnosis. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Specificity of head-up tilt testing in adolescents: effect of various degrees of tilt challenge in normal control subjects.

    Science.gov (United States)

    Lewis, D A; Zlotocha, J; Henke, L; Dhala, A

    1997-10-01

    This study sought to determine the specificity of commonly used tilt protocols in children. Tilt table testing is commonly utilized in the evaluation of children and adolescents with syncope despite a lack of uniformity in tilt protocols and a lack of studies of specificity in normal control subjects. Sixty-nine normal control volunteers (12 to 18 years old, 38 male, 31 female) with no previous history of syncope, presyncope or arrhythmia underwent tilting to 80 degrees, 70 degrees or 60 degrees for a maximum of 30 min on a motorized table with a footboard support. Autonomic maneuvers, including deep breathing, carotid massage, Valsalva maneuver and diving reflex, were performed before tilt testing to determine whether the response to these maneuvers could identify subjects prone to fainting during tilt testing. Symptoms of presyncope and frank syncope were elicited in 24 of 69 subjects (13 male, 11 female): 6 (60%) of 10 were tilted at 80 degrees, 9 (29%) of 31 at 70 degrees and 9 (32%) of 28 at 60 degrees. Tilt testing at 80 degrees was terminated after the tenth subject by the institutional review board. The mean time to a positive test response was 10.5 min at 80 degrees, 14.2 min at 70 degrees and 13.2 min at 60 degrees. In the 80 degrees tilt, 4 of 10 subjects had a positive response within 10 minutes, whereas only 3 of 31 and 2 of 28 had a positive response within testing were similar with respect to age; gender; PR, QRS and QT intervals; and baseline heart rate and blood pressure. Likewise, responses to other autonomic function tests performed were similar in tilt-positive and tilt-negative patients. The power for detecting a significant difference between patients tilted at 80 degrees versus 60 degrees and 70 degrees was 0.45 and for detecting differences in autonomic tone between tilt-positive (n = 24) and tilt-negative (n = 45) subjects was 0.8. Children appear to be more susceptible to orthostatic stress than adults. Therefore, tilt protocols commonly

  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. 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.

  16. 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.

  17. 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

    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.......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....

  18. Functional imaging of human extraocular muscles in head tilt dependent hypertropia.

    Science.gov (United States)

    Demer, Joseph L; Kung, Jennifer; Clark, Robert A

    2011-05-09

    Although alteration in hypertropia induced by head tilt is considered a clinical criterion for diagnosis of superior oblique (SO) palsy, the mechanism of this head-tilt-dependent hypertropia (HTDHT) is unclear. In this study, magnetic resonance imaging (MRI) was used to study extraocular muscle (EOM) responses to head tilt in HTDHT. Orbital MRI was used to study 16 normal subjects and 22 subjects with HTDT, of whom 12 had unilateral SO atrophy and 10 had "masquerading" SO palsy with normal SO size. Sizes and paths of all EOMs were compared in 90° roll tilts. Normal subjects exhibited the expected 3° to 7° physiologic extorsion of all four rectus pulleys in the orbit up-versus-down roll positions, corresponding to ocular counterrolling. In orbits with SO atrophy, the lateral (LR) and inferior rectus (IR) pulleys paradoxically intorted by approximately 2°. Subjects with HTDHT but normal SO size exhibited reduced or reversed extorsion of the medial, superior, and LR pulleys, whereas pulley shift was normal in nonhypertropic fellow orbits in HTDHT. In normal subjects and in SO atrophy, the inferior oblique (IO) muscle contracted in the orbit up-versus-down roll position, but paradoxically relaxed in HTDHT without SO atrophy. The ipsilesional IR and LR pulleys shift abnormally during head tilt in HTDHT with SO atrophy. In HTDHT without SO atrophy, the ipsilesional MR, SO, and LR pulleys shift abnormally, and the IO relaxes paradoxically during head tilt. These widespread alterations in EOM pulling directions suggest that complex neural adjustments to the otolith-ocular reflexes mediate HTDHT.

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

    Science.gov (United States)

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

    1990-01-01

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

  20. RE-EXAMINING SUNSPOT TILT ANGLE TO INCLUDE ANTI-HALE STATISTICS

    Energy Technology Data Exchange (ETDEWEB)

    McClintock, B. H. [University of Southern Queensland, Toowoomba, 4350 (Australia); Norton, A. A. [HEPL, Stanford University, Palo Alto, CA 94305 (United States); Li, J., E-mail: u1049686@umail.usq.edu.au, E-mail: aanorton@stanford.edu, E-mail: jli@igpp.ucla.edu [Department of Earth, Planetary, and Space Sciences, University of California at Los Angeles, Los Angeles, CA 90095 (United States)

    2014-12-20

    Sunspot groups and bipolar magnetic regions (BMRs) serve as an observational diagnostic of the solar cycle. We use Debrecen Photohelographic Data (DPD) from 1974-2014 that determined sunspot tilt angles from daily white light observations, and data provided by Li and Ulrich that determined sunspot magnetic tilt angle using Mount Wilson magnetograms from 1974-2012. The magnetograms allowed for BMR tilt angles that were anti-Hale in configuration, so tilt values ranged from 0 to 360° rather than the more common ±90°. We explore the visual representation of magnetic tilt angles on a traditional butterfly diagram by plotting the mean area-weighted latitude of umbral activity in each bipolar sunspot group, including tilt information. The large scatter of tilt angles over the course of a single cycle and hemisphere prevents Joy's law from being visually identified in the tilt-butterfly diagram without further binning. The average latitude of anti-Hale regions does not differ from the average latitude of all regions in both hemispheres. The distribution of anti-Hale sunspot tilt angles are broadly distributed between 0 and 360° with a weak preference for east-west alignment 180° from their expected Joy's law angle. The anti-Hale sunspots display a log-normal size distribution similar to that of all sunspots, indicating no preferred size for anti-Hale sunspots. We report that 8.4% ± 0.8% of all bipolar sunspot regions are misclassified as Hale in traditional catalogs. This percentage is slightly higher for groups within 5° of the equator due to the misalignment of the magnetic and heliographic equators.

  1. RE-EXAMINING SUNSPOT TILT ANGLE TO INCLUDE ANTI-HALE STATISTICS

    International Nuclear Information System (INIS)

    McClintock, B. H.; Norton, A. A.; Li, J.

    2014-01-01

    Sunspot groups and bipolar magnetic regions (BMRs) serve as an observational diagnostic of the solar cycle. We use Debrecen Photohelographic Data (DPD) from 1974-2014 that determined sunspot tilt angles from daily white light observations, and data provided by Li and Ulrich that determined sunspot magnetic tilt angle using Mount Wilson magnetograms from 1974-2012. The magnetograms allowed for BMR tilt angles that were anti-Hale in configuration, so tilt values ranged from 0 to 360° rather than the more common ±90°. We explore the visual representation of magnetic tilt angles on a traditional butterfly diagram by plotting the mean area-weighted latitude of umbral activity in each bipolar sunspot group, including tilt information. The large scatter of tilt angles over the course of a single cycle and hemisphere prevents Joy's law from being visually identified in the tilt-butterfly diagram without further binning. The average latitude of anti-Hale regions does not differ from the average latitude of all regions in both hemispheres. The distribution of anti-Hale sunspot tilt angles are broadly distributed between 0 and 360° with a weak preference for east-west alignment 180° from their expected Joy's law angle. The anti-Hale sunspots display a log-normal size distribution similar to that of all sunspots, indicating no preferred size for anti-Hale sunspots. We report that 8.4% ± 0.8% of all bipolar sunspot regions are misclassified as Hale in traditional catalogs. This percentage is slightly higher for groups within 5° of the equator due to the misalignment of the magnetic and heliographic equators

  2. Circadian blood pressure and systemic haemodynamics during 42 days of 6 degrees head-down tilt

    NARCIS (Netherlands)

    Voogel, A. J.; Stok, W. J.; Pretorius, P. J.; van Montfrans, G. A.; Langewouters, G. J.; Karemaker, J. M.

    1997-01-01

    Head-down tilted bedrest is a ground-based microgravity simulation model. Since in this position the influence of chief external determinants of circadian blood pressure variation, i.e. activity and posture, are reduced, it may reveal endogenous oscillatory factors. The effects of 42 days of 6

  3. 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

    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...

  4. 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.

  5. Evaluation of spontaneous baroreflex response after 28 days head down tilt bedrest

    Science.gov (United States)

    Hughson, R. L.; Yamamoto, Y.; Butler, G. C.; Güell, A.; Gharib, C.

    The spontaneous baroreflex response was evaluated during supine rest and head up tilt (60°) before and immediately after a 28 day 6° HDT bedrest in 6 healthy adult men (age 30-42 years). Sequences of 3 or more beats where RR-interval and systolic blood pressure changed in the same direction were used to evaluate baroreflex response slope (BRS). Prior to bedrest, the mean BRS and RR-interval were 18.0 ± 3.9 ms/mm Hg and 926 ± 61 ms at rest and 10.5 ± 2.5 ms/mm Hg and 772 ± 63 ms during the first 10 min of 60° tilt. Following bedrest, these values changed to 15.6 ± 2.7 ms/mm Hg and 780 ± 53 ms at rest, and to 6.5 ± 1.2 ms/mm Hg and 636 ± 44 ms during tilt. Thus, (1) the spontaneous baroreflex can be evaluated in human subjects during experiments of orthostatic stress; (2) the baroreflex slope was reduced on going from supine to the head up tilt position; and (3) 28 days of bedrest reduced the spontaneous baroreflex slope.

  6. [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.

  7. The Effect of Pelvic Tilt and Femoral Head Size on Hip Range-of-Motion to Impingement.

    Science.gov (United States)

    McCarthy, Thomas F; Nevelos, Jim; Elmallah, Randa K; Chughtai, Morad; Khlopas, Anton; Alipit, Vincent; Wagner, Timothy C; Mont, Michael A

    2017-11-01

    About 50%-70% of dislocators have cups placed within so-called "safe zones." It has been postulated that factors such as femoral head size and pelvic tilt, obliquity, or rotation may influence postoperative stability. Therefore, we assessed varying degrees of pelvic tilt and head sizes on the range of motion (ROM) to impingement. A hip simulator was used to import models of 10 subjects who performed object pickup, squatting, and low-chair rising. Parameters were set for pelvic tilt, stem version, and the specific motions as defined by the subjects. Femur-to-pelvis relative motions were determined for abduction/adduction, internal/external rotation, and flexion/extension. Varying tilt angles were tested. Thirty-two millimeter and 36-mm head with a standard cup and 42-mm dual mobility cup were tested. Cup orientations for abduction and anteversion combinations were chosen, and computations of minimum clearances or impingement between components were made. The ROM to impingement varied with the different pelvic tilts and femoral head sizes and with the different motions. The larger the head size, the larger the impingement-free ROM. Negative 10° of pelvic tilt led to the largest impingement-free zone, whereas 10° of forward tilt was associated with fewer impingement-free cup anteversion and abduction angle combinations. Variations in pelvic tilt had the greatest influence on object pickup and affected the impingement-free "safe zone." Targets for impingement-free motion may be smaller when considering varying pelvic tilts and femoral head sizes, particularly for certain activities, such as object pickup. These findings may indicate the need for more individualized patient planning. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. 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.

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

    Science.gov (United States)

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

    2014-01-01

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

  10. Laterality in semi-free-ranging black and white ruffed lemurs (Varecia variegata variegata): head-tilt correlates with hand use during feeding.

    Science.gov (United States)

    Nelson, Eliza L; O'Karma, Jaime M; Ruperti, Felicia S; Novak, Melinda A

    2009-12-01

    Previous studies in human and chimpanzee infants have identified a predictive relationship between early rightward head orientation and later right hand use. Data from lemurs suggest a leftward bias in hand preference, but there are no data on head positioning. The purpose of this study was to examine the relationship between head and hand preferences in the black and white ruffed lemur (Varecia variegata variegata). Ruffed lemurs rotate the head vertically during chewing in a behavior called head-tilting. Frequency of head-tilting and bouts of unimanual hand use were measured during normal feeding in a semi-free-ranging population of lemurs. Subjects were provisioned at feeding platforms twice daily with fresh fruits, vegetables, and other food items. Sampling was spontaneous and all observations were videotaped. No group-level bias was found for head-tilting, but a left hand bias emerged for hand use. A positive relationship was found between direction of head-tilting preference and direction of hand use preference such that left head-tilts increased as left hand use increased. Furthermore, left head-tilts increased as the degree of hand preference lateralization increased. When the hand used to bring food to the mouth just before head-tilting was examined, there was a strong bias for the left hand to precede left head-tilts. For right head-tilts, however, lemurs were equally likely to use either hand before head-tilting. Overall a strong relationship was found between the left hand and left head-tilting in black and white ruffed lemurs, suggesting a common link between these behaviors. However, the direction of bias was different from that seen in human and chimpanzee studies. Additional studies on patterns of laterality would be informative for understanding how laterality has changed across the primate order and the adaptive significance of laterality in primates.

  11. The Effect of Head Positioning and Head Tilting on the Incidence of Intraventricular Hemorrhage in Very Preterm Infants : A Systematic Review

    NARCIS (Netherlands)

    de Bijl-Marcus, Karen A; Brouwer, Annemieke J|info:eu-repo/dai/nl/334070805; de Vries, Linda S|info:eu-repo/dai/nl/072995408; van Wezel-Meijler, Gerda

    2017-01-01

    BACKGROUND: Despite advances in neonatal intensive care, germinal matrix-intraventricular hemorrhage (GMH-IVH) remains a frequent, serious complication of premature birth. Neutral head position and head tilting have been suggested to reduce the risk of GMH-IVH in preterm infants during the first 72

  12. The Effect of Head Positioning and Head Tilting on the Incidence of Intraventricular Hemorrhage in Very Preterm Infants: A Systematic Review.

    Science.gov (United States)

    de Bijl-Marcus, Karen A; Brouwer, Annemieke J; de Vries, Linda S; van Wezel-Meijler, Gerda

    2017-01-01

    Despite advances in neonatal intensive care, germinal matrix-intraventricular hemorrhage (GMH-IVH) remains a frequent, serious complication of premature birth. Neutral head position and head tilting have been suggested to reduce the risk of GMH-IVH in preterm infants during the first 72 h of life. The aim of this study was to provide a systematic review of the effect of neutral head positioning and head tilting on the incidence of GMH-IVH in very preterm infants (gestational age ≤30 weeks). In addition, we reviewed their effect on cerebral hemodynamics and oxygenation. Literature was searched (June 2016) in the following electronic databases: CINAHL, Embase, Medline, SCOPUS, and several trial registers. One underpowered trial studied the effect of head positioning on the incidence of GMH-IVH. This randomized controlled trial enrolled 48 preterm infants and found no effect on the occurrence of GMH-IVH. Three observational studies investigated the effect of head rotation and/or tilting on cerebral oxygenation in 68 preterm infants in total. Their results suggest that cerebral oxygenation is not significantly affected by changes in head positioning. The effect of head positioning and/or tilting on cerebral hemodynamics was described in 2 observational studies of 28 preterm infants and found no significant effect. There is insufficient evidence regarding the effect of head positioning and tilting on the incidence of GMH-IVH and cerebral hemodynamics and oxygenation in preterm infants. We recommend further research in this field, especially in extremely preterm and clinically unstable infants during the first postnatal days. © 2016 S. Karger AG, Basel.

  13. Complexity of cardiovascular rhythms during head-up tilt test by entropy of patterns.

    Science.gov (United States)

    Wejer, Dorota; Graff, Beata; Makowiec, Danuta; Budrejko, Szymon; Struzik, Zbigniew R

    2017-05-01

    The head-up tilt (HUT) test, which provokes transient dynamical alterations in the regulation of cardiovascular system, provides insights into complex organization of this system. Based on signals with heart period intervals (RR-intervals) and/or systolic blood pressure (SBP), differences in the cardiovascular regulation between vasovagal patients (VVS) and the healthy people group (CG) are investigated. Short-term relations among signal data represented symbolically by three-beat patterns allow to qualify and quantify the complexity of the cardiovascular regulation by Shannon entropy. Four types of patterns: permutation, ordinal, deterministic and dynamical, are used, and different resolutions of signal values in the the symbolization are applied in order to verify how entropy of patterns depends on a way in which values of signals are preprocessed. At rest, in the physiologically important signal resolution ranges, independently of the type of patterns used in estimates, the complexity of SBP signals in VVS is different from the complexity found in CG. Entropy of VVS is higher than CG what could be interpreted as substantial presence of noisy ingredients in SBP of VVS. After tilting this relation switches. Entropy of CG occurs significantly higher than VVS for SBP signals. In the case of RR-intervals and large resolutions, the complexity after the tilt becomes reduced when compared to the complexity of RR-intervals at rest for both groups. However, in the case of VVS patients this reduction is significantly stronger than in CG. Our observations about opposite switches in entropy between CG and VVS might support a hypothesis that baroreflex in VVS affects stronger the heart rate because of the inefficient regulation (possibly impaired local vascular tone alternations) of the blood pressure.

  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 ....01) and an increase in thoracic electric impedance from 38.6 +/- 2.1 to 42.6 +/- 2.1 omega (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

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

    Science.gov (United States)

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

    2011-04-01

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

  16. Non-Invasive Intracranial Pressure Estimation During Combined Exposure to CO₂ and Head-Down Tilt.

    Science.gov (United States)

    Kurazumi, Takuya; Ogawa, Yojiro; Yanagida, Ryo; Morisaki, Hiroshi; Iwasaki, Ken-Ichi

    2018-04-01

    Exposure to carbon dioxide (CO2) and cephalad fluid shift are considered factors that affect intracranial pressure (ICP) during spaceflight. Increases in ICP were reported during cephalad fluid shift induced by head-down tilt (HDT), while little is known regarding the effect of additional CO2 during HDT on ICP. Therefore, we tested the hypothesis that this combination increases ICP more than HDT alone. There were 15 healthy male volunteers who underwent 4 types of 10-min interventions consisting of Placebo/Supine (air and supine), CO2/Supine (3% CO2 and supine, CO2 alone), Placebo/HDT (air and -10° HDT, HDT alone), and CO2/HDT (3% CO2 and -10° HDT, combination). Using arterial blood pressure (ABP) and cerebral blood flow velocity waveforms, ICP was estimated noninvasively before and during the four interventions. Two calculation methods were employed. One is based on the signal transformation from ABP to ICP with the intracranial component as a "black box" system (nICP_BB), and the other is based on the equation ICP = ABP - cerebral perfusion pressure, reflecting critical closing pressure (nICP_CrCP). Both nICP_BB and nICP_CrCP significantly increased during Placebo/HDT and CO2/HDT, although there was no statistically significant difference between the nICP indexes of these two interventions. Increases in ICP were observed during both Placebo/HDT and CO2/HDT. Contrary to our hypothesis, the combination of 3% CO2 and -10° HDT did not increase ICP remarkably compared to -10° HDT alone. Therefore, the addition of 3% CO2 is considered to have little effect on increasing ICP during cephalad fluid shift.Kurazumi T, Ogawa Y, Yanagida R, Morisaki H, Iwasaki K. Non-invasive intracranial pressure estimation during combined exposure to CO2 and head-down tilt. Aerosp Med Hum Perform. 2018; 89(4):365-370.

  17. 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, p<0.05) while plasma osmolality remained unchanged (NS). Pre-exercise Tre was elevated after HDT24 (36.71 degrees C +/-0.06 HDT1 vs. 36.93 degrees C+/-0.11 HDT24, p<0.05). The 70 min of exercise did not alter this relationship (p<0.05) with respective end exercise increases in Tre to 38.01 degrees C and 38.26 degrees C (degrees = 1.30 degrees C (HDT1) and 1.33 degrees C (HDT24)). While there were no pre-exercise differences in mean skin temperature (Tsk), a significant (p<0.05) time x treatment interaction occurred during exercise: after min 30 in HDT24 the Tsk leveled off at 31.1 degrees C, while it continued to increase reaching 31.5 degrees C at min 70 in HDT1. A similar response (NS) occurred in skin blood velocity. Neither local sweating rates nor changes in body weight during exercise of -1.63+/-0.24 kg (HDT1) or - 1.33+/-0.09 kg (HDT24) were different (NS) between experiments. CONCLUSION: While HDT24 resulted in elevated pre-exercise Tre, reduced PV

  18. Inferior oblique overaction/contracture following retrobulbar anesthesia for cataract extraction with a positive Bielschowsky Head Tilt test to the contralateral shoulder. A report of one case.

    Science.gov (United States)

    Khawam, Edward; El-Dairi, Mays; Al-Haddad, Christine; Younis, Mohammad

    2004-01-01

    This is a report of a patient with diplopia, hypertropia, extorsion and a positive Bielschowsky Head Tilt Test following retrobulbar anesthesia, due to an inferior oblique muscle overaction-contracture. Oculomotor and sensorimotor examinations and ocular motility recordings and Bielschowsky Head Tilt Test demonstrated overaction characteristics overpowering the contracture characteristics of the involved inferior oblique muscle. Weakening of the overacting inferior oblique eliminated the vertical and torsional deviations and the forced head tilt difference upon tilting the head to either shoulder. It also normalized ocular motility and resulted in a symptom-free patient. Oblique muscle dysfunction with vertical and torsional deviations and a positive Bielschowsky Head Tilt Test can result from retrobulbar anesthesia.

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

    Science.gov (United States)

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

    1992-01-01

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

  20. Cardiovascular models of simulated moon and mars gravities: head-up tilt vs. lower body unweighting.

    Science.gov (United States)

    Kostas, Vladimir I; Stenger, Michael B; Knapp, Charles F; Shapiro, Robert; Wang, Siqi; Diedrich, André; Evans, Joyce M

    2014-04-01

    In this study we compare two models [head-up tilt (HUT) vs. body unweighting using lower body positive pressure (LBPP)] to simulate Moon, Mars, and Earth gravities. A literature search did not reveal any comparisons of this type performed previously. We hypothesized that segmental fluid volume shifts (thorax, abdomen, upper and lower leg), cardiac output, and blood pressure (BP), heart rate (HR), and total peripheral resistance to standing would be similar in the LBPP and HUT models. There were 21 subjects who were studied while supine (simulation of spaceflight) and standing at 100% (Earth), 40% (Mars), and 20% (Moon) bodyweight produced by LBPP in Alter-G and while supine and tilted at 80 degrees, 20 degrees, and 10 degrees HUT (analogues of Earth, Mars, and Moon gravities, respectively). Compared to supine, fluid shifts from the chest to the abdomen, increases in HR, and decreases in stroke volume were greater at 100% bodyweight than at reduced weights in response to both LBPP and HUT. Differences between the two models were found for systolic BP, diastolic BP, mean arterial BP, stroke volume, total peripheral resistance, and thorax and abdomen impedances, while HR, cardiac output, and upper and lower leg impedances were similar. Bodyweight unloading via both LBPP and HUT resulted in cardiovascular changes similar to those anticipated in actual reduced gravity environments. The LBPP model/Alter-G has the advantage of providing an environment that allows dynamic activity at reduced bodyweight; however, the significant increase in blood pressures in the Alter-GC may favor the HUT model.

  1. Sympathetic neural and hemodynamic responses to head-up tilt during isoosmotic and hyperosmotic hypovolemia.

    Science.gov (United States)

    Posch, Alexander M; Luippold, Adam J; Mitchell, Katherine M; Bradbury, Karleigh E; Kenefick, Robert W; Cheuvront, Samuel N; Charkoudian, Nisha

    2017-10-01

    We hypothesized that muscle sympathetic nerve activity (MSNA) during head-up tilt (HUT) would be augmented during exercise-induced (hyperosmotic) dehydration but not isoosmotic dehydration via an oral diuretic. We studied 26 young healthy subjects (7 female, 19 male) divided into three groups: euhydrated (EUH, n = 7), previously exercised in 40°C while maintaining hydration; dehydrated (DEH, n = 10), previously exercised in 40°C during which ~3% of body weight was lost via sweat loss; and diuretic (DIUR, n = 9), a group that did not exercise but lost ~3% of body weight via diuresis (furosemide, 80 mg by mouth). We measured MSNA, heart rate (HR), and blood pressure (BP) during supine rest and 30° and 45° HUT. Plasma volume (PV) decreased similarly in DEH (-8.5 ± 3.3%) and DIUR (-11.4 ± 5.7%) ( P > 0.05). Plasma osmolality was similar between DIUR and EUH (288 ± 4 vs. 284 ± 5 mmol/kg, respectively) but was significantly higher in DEH (299 ± 5 mmol/kg) ( P HR and MSNA increased in all subjects during HUT (main effect of position; P HR were higher in DEH compared with DIUR ( P HR with HUT were larger in both hypovolemic groups compared with EUH ( P controlling HR responses during dehydration, and a stronger role for osmolality in control of SNA. NEW & NOTEWORTHY Interactions of volume regulation with control of vascular sympathetic nerve activity (SNA) have important implications for blood pressure regulation. Here, we demonstrate that SNA and heart rate (HR) during hyperosmotic hypovolemia (exercise-induced) were augmented during supine and tilt compared with isoosmotic hypovolemia (diuretic), which primarily augmented the HR response. Our data suggest that hypovolemia per se had a larger role in controlling HR responses, whereas osmolality had a stronger role in control of SNA.

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

    Science.gov (United States)

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

    1993-01-01

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

  3. 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

  4. Determinants of a positive response to carotid sinus massage and head-up tilt testing.

    Science.gov (United States)

    Milton, James C; Lee, Thomas C; Jackson, Stephen H D

    2009-11-01

    Orthostatic hypotension (OH) and carotid sinus hypersensitivity (CSH) are common causes of syncope in older people. The aim of this study was to determine if patient's age, sex and presenting symptoms influence the result of carotid sinus massage and head-up tilt testing. Retrospective analysis of the database and reports was carried out between 1995 and 2006 at a tertiary referral centre. Patient's age, sex, presenting symptoms and test result were examined. Presenting symptoms were classified as syncope, falls or dizzy spells. Of the 1583 tests reported, OH was present in 402 patients (25.4%), of whom 175 (11.1%) were symptomatic. 188 of 1464 (12.8%) patients undergoing carotid sinus massage had evidence of CSH, of which 156 were symptomatic. Male patients were significantly more likely to have symptomatic CSH than female patients (odds ratio 2.28, 95% CI 1.54 to 3.04, p<0.01). There were non-significant trends to increased diagnosis of symptomatic OH with increasing age, male sex and referral with syncope. There were non-significant trends to increased diagnosis of symptomatic CSH with increasing age and referral with syncope. Male sex, increasing age and being referred with syncope were all associated with an increased likelihood of receiving a diagnosis of either OH or CSH. The overall prevalence of CSH was lower than in previous studies, which may reflect different patient populations.

  5. Clinical findings as predictors of positivity of head-up tilt table test in neurocardiogenic syncope.

    Science.gov (United States)

    Asensio, Enrique; Oseguera, Jorge; Loría, Alvar; Gómez, María; Narváez, René; Dorantes, Joel; Hernández, Pablo; Orea, Arturo; Rebollar, Verónica; Ocaranza, Raymundo

    2003-01-01

    Neurocardiogenic (vasovagal) syncope occurs frequently and can be diagnosed with the head-up tilt table (HUTT) test. Our objective in this study was to identify clinical predictors of the positivity of HUTT test in neurocardiogenic syncope. We conducted a prospective study of 117 cases (81 women and 36 men, 13-85 years of age) referred to our Institution for HUTT testing. The ability of 10 symptoms and signs of clinical history to predict HUTT positivity were evaluated using logistic regression analysis. We observed a low rate of test-negative cases (24%) and 89 positives. Nearly all positives (87/89) were neurocardiogenic, principally of vasodepressor and mixed types (43 and 34 cases, respectively) and a few were cardioinhibitory (10, mostly young males). Regression analysis established that dizziness, nausea, and diaphoresis in past history were associated with HUTT positivity nearly 25 times more frequently than when absent. Our three conclusions are that syncope in absence of heart disease accompanied by dizziness, nausea, and diaphoresis may be treated as neurocardiogenic in settings where no HUTT is available. In addition, our low rate of negative tests may have been the result of our reexamining referrals prior to deciding test performance, and high frequency of young males in cardioinhibitory syncope needs further research.

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

    Science.gov (United States)

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

    1994-01-01

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

  7. The repeatability of left ventricular volume assessment by a new ambulatory radionuclide monitoring system during head-up tilt

    International Nuclear Information System (INIS)

    Takase, Bonpei; Hosaka, Haruhiko; Kitamura, Katsuhiro

    2001-01-01

    The precise measurement of changes in left ventricular volume is important to elucidate the mechanisms of neurally mediated syncope. This study was conducted to determine whether or not a brand-new ambulatory radionuclide monitoring system (C-VEST system) can be clinically used to easily and precisely measure left ventricular volume and function in tilt testing. To assess the repeatability of the C-VEST system, 12 healthy volunteers (mean age 24±4 years old) underwent 20 minute head-up tilt testing and we measured the temporal changes in left ventricular volume and ejection fraction twice a day (first and second studies). To investigate the changes in the C-VEST measurements and the detector position in the first and second studies, tilt testing was performed with an 80-degree passive tilt, which is the same as the standard procedure used in diagnosing neurally mediated syncope. The coefficient of repeatability for both the C-VEST and detector position was well within the clinical range (coefficient of repeatability in left ventricular volume ranged from 1.7 to 2.8; coefficient of repeatability in the detector position ranged from 2.3 to 3.1). Precise evaluation of the left ventricular volume can be achieved by an ambulatory radionuclide monitoring system in tilt testing. (author)

  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

    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......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...... hormones, cortisol, adrenomedullary (plasma adrenaline; A) as well as vagal activity (plasma pancreatic polypeptide) were markedly increased, whereas sympathetic activity (plasma NA) decreased. The 5-HT1+2 receptor antagonist methysergide did not significantly interfere with cardiovascular variables...

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

    Science.gov (United States)

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

    1994-01-01

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

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

    Science.gov (United States)

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

    2004-01-01

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

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

    Science.gov (United States)

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

    2015-04-01

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

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

    Science.gov (United States)

    ŚwiÄ tek, Eliza; Cybulski, Gerard; Koźluk, Edward; PiÄ tkowska, 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.

  13. Automatic Prompting and Positive Attention to Reduce Tongue Protrusion and Head Tilting by Two Adults with Severe to Profound Intellectual Disabilities

    Science.gov (United States)

    Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; Didden, Robert; Pichierri, Sabrina

    2010-01-01

    This study assessed a simple behavioral strategy for reducing stereotypic tongue protrusion and forward head tilting displayed by a woman and a man with severe to profound intellectual disabilities. The strategy involved (a) auditory prompting (i.e., verbal encouragements to keep the tongue in the mouth or the head upright) delivered automatically…

  14. Kernel based support vector machine for the early detection of syncope during head-up tilt test

    International Nuclear Information System (INIS)

    Khodor, N; Amoud, H; Khalil, M; Matelot, D; Carrault, G; Ville, N; Carre, F; Hernandez, A

    2014-01-01

    This study aims to analyze the autonomic nervous system response during head-up tilt test (HUTT), by exploring the changes in dynamic properties of heart rate variability in subjects with and without syncopes, to predict the outcome of HUTT. Baroreflex response, as well as linear and non-linear parameters of RR-interval time series, have been extracted from the ECG of 66 subjects: 35 with and 31 without syncope during HUTT. The results show that, when considering the first 15 min of tilting position, the total power spectrum, the standard deviation, the long-term fractal scale of RR-interval and ΔRR-interval of time series increase, while the sample entropy decreases in the positive group compared to the negative one. These indices may be good predictors of positive response in patients with reflex syncope. Additionally, an analysis of the first 15 min of tilting position using kernel support vector machines leads to a correct classification of 85% of patients, within negative and positive response groups (specificity = 80.6% and sensitivity = 88.5%). In medical applications, it is important to avoid false negative diagnosis of syncopes during HUTT. Taking this into account, an overall accuracy of 72.1% can be obtained in the same window allowing the reduction of the examination time in the clinical domain. (paper)

  15. 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

  16. Impaired Tilt Suppression of Post-Rotatory Nystagmus and Cross-Coupled Head-Shaking Nystagmus in Cerebellar Lesions: Image Mapping Study.

    Science.gov (United States)

    Lee, Sun-Uk; Choi, Jeong-Yoon; Kim, Hyo-Jung; Park, Jeong-Jin; Zee, David S; Kim, Ji-Soo

    2017-02-01

    We sought to determine the cerebellar structures responsible for tilt suppression of post-rotatory nystagmus. We investigated ocular motor findings and MRI lesions in 73 patients with isolated cerebellar lesions who underwent recording of the vestibulo-ocular reflex (VOR) using rotatory chair tests. Tilt suppression of post-rotatory nystagmus was diminished in 27 patients (27/73, 37.0 %). The gains of the VOR and the TCs of per- and post-rotatory nystagmus did not differ between the patients with diminished and with normal tilt suppression. The patients with impaired tilt suppression showed perverted ("cross-coupled") head-shaking nystagmus (pHSN) and central positional nystagmus (CPN) more frequently than those with normal responses. Tilt suppression was impaired in five (71.4 %) of the seven patients with isolated nodulus and uvular infarction. Probabilistic lesion-mapping analysis showed that the nodulus and uvula are responsible for tilt suppression. Impaired tilt suppression may be ascribed to disruption of cerebellar contribution to the vestibular velocity-storage mechanism, which integrates information from the semicircular canals and otolith organs to help derive the brain's estimate of the head orientation relative to the pull of gravity.

  17. Handling and carrying head for nuclear fuel assemblies and installation including this head

    International Nuclear Information System (INIS)

    Artaud, R.; Cransac, J.P.; Jogand, P.

    1986-01-01

    The present invention proposes a handling and carrying head ensuring efficiently the cooling of the nuclear fuel asemblies it transports so that any storage in liquid metal in a drum within or adjacent the reactor vessel is suppressed. The invention claims also a nuclear fuel handling installation including the head; it allows a longer time between loading and unloading campaigns and the space surrounding the reactor vessel keeps free without occupying a storage zone within the vessel [fr

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

    Science.gov (United States)

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

    1992-01-01

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

  19. Cardiac autonomic responses to head-up tilt in obese adolescents

    OpenAIRE

    Brunetto, Antônio Fernando; Roseguini, Bruno Tesini; Silva, Bruno Moreira; Hirai, Daniel Müller; Guedes, Dartagnan Pinto

    2005-01-01

    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 freqüên...

  20. Medial percutaneous hemi-epiphysiodesis improves the valgus tilt of the femoral head in developmental dysplasia of the hip (DDH) type-II avascular necrosis.

    Science.gov (United States)

    Agus, Haluk; Önvural, Burak; Kazimoglu, Cemal; Reisoglu, Ali; Kalenderer, Onder

    2015-01-01

    Avascular necrosis (AVN) is a major cause of disability after treatment of developmental dysplasia of the hip (DDH), leading to femoral head deformity, acetabular dysplasia, and osteoarthritis in adult life. Type-II AVN is characterized by retarded growth in the lateral aspect of the physis or by premature lateral fusion, which produces a valgus deformity of the head on the neck of the femur. We investigated the effect of medial percutaneous hemi-epiphysiodesis as a novel technique in the treatment of late-diagnosed type-II AVN. 9 patients (11 hips) with a diagnosis of type-II AVN who underwent medial percutaneous hemi-epiphysiodesis after the surgical treatment for DDH were included in the study. 10 patients (12 hips) with the same diagnosis but who did not undergo hemi-epiphysodesis were chosen as a control group. Preoperative and postoperative articulotrochanteric distances, head-shaft angles, CE (center-edge) angles, and physeal inclination angles were measured. The treatment group underwent medial hemi-epiphysodesis at a mean age of 8 years. The mean ages of the treatment group and the control group at final follow-up were 14 and 12 years respectively. The mean duration of follow-up was 5.7 years in the treatment group and 8.3 years in the control group. Preoperative articulotrochanteric distance, head-shaft angle, and functional outcome at the final follow-up assessment were similar in the 2 groups. However, preoperative and postoperative CE angles and physeal inclination angles differed significantly in the treatment group (p < 0.05). The final epiphyseal valgus angles were better in the treatment group than in the control group (p = 0.05). The treatment group improved after the operation. Medial percutaneous epiphysiodesis performed through a mini-incision under fluoroscopic control is a worthwhile modality in terms of changing the valgus tilt of the femoral head.

  1. SU-E-T-230: Creating a Large Number of Focused Beams with Variable Patient Head Tilt to Improve Dose Fall-Off for Brain Radiosurgery

    International Nuclear Information System (INIS)

    Chiu, J; Ma, L

    2015-01-01

    Purpose: To develop a treatment delivery and planning strategy by increasing the number of beams to minimize dose to brain tissue surrounding a target, while maximizing dose coverage to the target. Methods: We analyzed 14 different treatment plans via Leksell PFX and 4C. For standardization, single tumor cases were chosen. Original treatment plans were compared with two optimized plans. The number of beams was increased in treatment plans by varying tilt angles of the patient head, while maintaining original isocenter and the beam positions in the x-, y- and z-axes, collimator size, and beam blocking. PFX optimized plans increased beam numbers with three pre-set tilt angles, 70, 90, 110, and 4C optimized plans increased beam numbers with tilt angles increasing arbitrarily from range of 30 to 150 degrees. Optimized treatment plans were compared dosimetrically with original treatment plans. Results: Comparing total normal tissue isodose volumes between original and optimized plans, the low-level percentage isodose volumes decreased in all plans. Despite the addition of multiple beams up to a factor of 25, beam-on times for 1 tilt angle versus 3 or more tilt angles were comparable (<1 min.). In 64% (9/14) of the studied cases, the volume percentage decrease by >5%, with the highest value reaching 19%. The addition of more tilt angles correlates to a greater decrease in normal brain irradiated volume. Selectivity and coverage for original and optimized plans remained comparable. Conclusion: Adding large number of additional focused beams with variable patient head tilt shows improvement for dose fall-off for brain radiosurgery. The study demonstrates technical feasibility of adding beams to decrease target volume

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

    Science.gov (United States)

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

    2011-01-01

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

  3. The impact of preload reduction with head-up tilt testing on longitudinal and transverse left ventricular mechanics.

    Science.gov (United States)

    Schneider, Caroline; Forsythe, Lynsey; Somauroo, John; George, Keith; Oxborough, David

    2018-01-03

    Left ventricular (LV) function is dependent on load, intrinsic contractility and relaxation with a variable impact on specific mechanics. Strain (ε) imaging allows the assessment of cardiac function however the direct relationship between volume and strain is currently unknown. The aim of this study was to establish the impact of preload reduction through head-up tilt (HUT) testing on simultaneous left ventricular (LV) longitudinal and transverse function and their respective contribution to volume change. A focused transthoracic echocardiogram was performed on 10 healthy male participants (23 ± 3 years,) in the supine position and following 1 min and 5 min of HUT testing. Raw temporal longitudinal ε (Ls) and transverse ε (Ts) values were exported and divided into 5% increments across the cardiac cycle and corresponding LV volumes were traced at each 5% increment. This provided simultaneous LV longitudinal and transverse ε and volume-loops (deformation-volume analysis - DVA). There was a leftward- shift of the ε -volume loop from supine to 1 min and 5 min of HUT, pmaintenance of LV filling in the setting of reduced preload. DVA provides information on the relative contribution of mechanics to a change in LV volume and may have a role in the assessment of clinical populations. © 2018 The authors.

  4. Does mental arithmetic before head up tilt have an effect on the orthostatic cardiovascular and hormonal responses?

    Science.gov (United States)

    Goswami, Nandu; Lackner, Helmut Karl; Papousek, Ilona; Montani, Jean-Pierre; Jezova, Daniela; Hinghofer-Szalkay, Helmut G.

    2011-05-01

    Passive head up tilt (HUT) and mental arithmetic (MA) are commonly used for providing mental and orthostatic challenges, respectively. In animal experiments, even a single exposure to a stressor has been shown to modify the response to subsequent stress stimulus. We investigated whether MA applied before HUT elicits synergistic responses in orthostatic heart rate (HR), cardiac output (CO), heart rate variability and arterial blood pressure. The 15 healthy young males were subjected to two randomized protocols: (a) HUT and (b) HUT preceded by MA, with sessions randomized and ≥2 weeks apart. Beat to beat continuous hemodynamic variables were measured and saliva samples taken for hormonal assay. HUT alone increased HR from 59±7 (baseline) to 80±10 bpm (mean±SD) and mean blood pressure (MBP) from 88±10 to 91±14 mmHg. HUT results after MA were not different from those with HUT alone. The activity of alpha amylase showed differences during the experiments irrespective of the protocols. We conclude that mental challenge does not affect orthostatic cardiovascular responses when applied before; the timing of mental loading seems to be critical if it is intended to alter cardiovascular responses to upright standing.

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

    Science.gov (United States)

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

    2012-01-01

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

  6. 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

  7. The acute effects of alcohol on cerebral hemodynamic changes induced by the head-up tilt test in healthy subjects.

    Science.gov (United States)

    Viski, Sandor; Orosz, Miklos; Czuriga-Kovacs, Katalin Reka; Magyar, Maria Tunde; Csiba, Laszlo; Olah, Laszlo

    2016-09-15

    Alcohol is a known triggering factor for orthostatic dysfunction, increasing the risk of neurally-mediated syncope. Since orthostatic tolerance may be affected by both systemic and cerebral hemodynamic changes, our aim was to investigate the acute effects of alcohol on cerebral vasoreactivity measured during the head-up tilt (HUT) test in 20 healthy subjects. Mean arterial blood pressure (mBP), heart rate, and flow parameters in both middle cerebral arteries (MCAs) were continuously recorded in the supine and during a 10-minute HUT positions before and after alcohol intake. The HUT test resulted in a more prominent decline of adjusted mBP at the level of MCAs (mBPMCA) and a significantly larger decrease of MCA mean flow velocities (MFVMCA) in the post-alcohol period than before alcohol intake. During the HUT phase, the relative decrease in MFVMCA was significantly smaller than the reduction in mBPMCA before drinking alcohol, while these changes were similar after alcohol ingestion. The cerebrovascular resistance index (CVRi) decreased during the HUT phase in the control period, however, it increased after alcohol intake. The similar decrease in mBPMCA and MFVMCA during orthostatic stress after alcohol ingestion together with the increased CVRi indicated the impairment of the compensatory vasodilation of cerebral resistance vessels, i.e. impaired cerebral autoregulation. These findings suggest that alcohol may contribute to impaired orthostatic tolerance not only by a hypotensive response but also by the alteration of cerebral blood flow regulation. Copyright © 2016. Published by Elsevier B.V.

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

    Science.gov (United States)

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

    2014-08-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

  10. 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.

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

    Science.gov (United States)

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

    2017-01-01

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

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

    Science.gov (United States)

    Furukawa, Toshiyuki

    2017-12-01

    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.

  13. 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.

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

    Science.gov (United States)

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

    2016-01-01

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

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

    OpenAIRE

    Furukawa, Toshiyuki

    2017-01-01

    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 ...

  16. Is the tilt of the lipid head group correlated with the number of intermolecular interactions at the bilayer interface?

    Science.gov (United States)

    Baczynski, Krzysztof; Markiewicz, Michal; Pasenkiewicz-Gierula, Marta

    2018-04-10

    Lipid and water molecules comprising the bilayer form an integral entity owing to only weak physical interactions. At the bilayer interface, these interactions chiefly involve hydrogen bonding and charge pairing. Lipid head groups make hydrogen bonds (H-bonds) predominantly with water, whereas inter-lipid H-bonds and charge pairs are less numerous. Both inter-lipid H-bonding and charge pairing depend on the distance and relative orientation of the interacting head groups. In this paper, correlations are analysed between the orientation of the lipid head group and the number of inter-lipid interactions at the interface of a bilayer made of galactolipids, forming direct inter-lipid H-bonds, and of phosphatidylcholines forming inter-lipid charge pairs. The correlations are not strong however, since in both bilayers they show a similar trend. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

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

    Science.gov (United States)

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

    2014-01-01

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

  18. Differences in Pre and Post Vascular Patterning Within Retinas from ISS Crew Members and Head-Down Tilt (HDT) Subjects by VESGEN Analysis

    Science.gov (United States)

    Murray, M. C.; Vizzeri, G.; Taibbi, G.; Mason, S. S.; Young, M.; Zanello, S. B.; Parsons-Wingerter, P.

    2018-01-01

    Accelerated research by NASA has investigated the significant risks incurred during long-duration missions in microgravity for Space Flight-Associated Neuro-ocular Syndrome (SANS, formerly known as Visual Impairments associated with Increased Intracranial Pressure, VIIP) [1]. For our study, NASA's VESsel GENeration Analysis (VESGEN) was used to investigate the role of retinal blood vessels in the etiology of SANS/VIIP. The response of retinal vessels to microgravity was evaluated in astronaut crew members pre and post flight to the International Space Station (ISS), and compared to the response of retinal vessels in healthy volunteers to 6deg head-down tilt during 70 days of bed rest (HDTBR). For the study, we are testing the hypothesis that long-term cephalad fluid shifts resulting in ocular and visual impairments are necessarily mediated in part by retinal blood vessels, and therefore are accompanied by structural adaptations of the vessels. METHODS: Vascular patterns in the retinas of crew members and HDTBR subjects extracted from 30deg infrared (IR) Heidelberg Spectralis images collected pre/postflight and pre/post HDTBR, respectively, were analyzed by VESGEN (patent pending). VESGEN is a mature, automated software developed as a research discovery tool for progressive vascular diseases in the retina and other tissues. The multi-parametric VESGEN analysis generates maps of branching arterial and venous trees quantified by parameters such as the fractal dimension (Df, a modern measure of vascular space-filling capacity), vessel diameters, and densities of vessel length and number classified into specific branching generations according to vascular physiological branching rules. The retrospective study approved by NASA's Institutional Review Board included the analysis of bilateral retinas in eight ISS crew members monitored by routine occupational surveillance and six HDTBR subjects (NASA FARU Campaign 11, for example). The VESGEN analysis was conducted in a

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

    Science.gov (United States)

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

    1994-01-01

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

  20. The impact of preload reduction with head-up tilt testing on longitudinal and transverse left ventricular mechanics: a study utilizing deformation volume analysis.

    Science.gov (United States)

    Schneider, Caroline; Forsythe, Lynsey; Somauroo, John; George, Keith; Oxborough, David

    2018-03-01

    Left ventricular (LV) function is dependent on load, intrinsic contractility and relaxation with a variable impact on specific mechanics. Strain (ε) imaging allows the assessment of cardiac function; however, the direct relationship between volume and strain is currently unknown. The aim of this study was to establish the impact of preload reduction through head-up tilt (HUT) testing on simultaneous left ventricular (LV) longitudinal and transverse function and their respective contribution to volume change. A focused transthoracic echocardiogram was performed on 10 healthy male participants (23 ± 3 years) in the supine position and following 1 min and 5 min of HUT testing. Raw temporal longitudinal ε (Ls) and transverse ε (Ts) values were exported and divided into 5% increments across the cardiac cycle and corresponding LV volumes were traced at each 5% increment. This provided simultaneous LV longitudinal and transverse ε and volume loops (deformation volume analysis - DVA). There was a leftward shift of the ε-volume loop from supine to 1 min and 5 min of HUT ( P  maintenance of LV filling in the setting of reduced preload. DVA provides information on the relative contribution of mechanics to a change in LV volume and may have a role in the assessment of clinical populations. © 2018 The authors.

  1. Osteonecrosis of the femoral head in lymphoma patients treated with combined chemotherapy including corticosteroids

    International Nuclear Information System (INIS)

    Nikkanen, T.A.V.; Maekinen, E.; Ekfors, T.O.; Hakkarainen, S.; Drysun, B.

    1980-01-01

    Osteonecrosis of the femoral head developed in two patients with malignant lymphoma treated with combined chemotherapy. Pain was the main symptom. It was not possible to radiographically distinguish the necrotic lesions from metastatic tumour growth, and in both cases only histological examination revealed the true nature of bone destruction. The large doses of corticosteroids included in the treatment regiments were most likely of more importance in the etiology of the necrosis than the cytostatic drugs proper. (orig.) [de

  2. [Cutaneous electro-gastroenterography for evaluation of changes in the gastrointestinal tract in consequence of various angles of inclination and length of head-down tilt].

    Science.gov (United States)

    Afonin, B V; Sedova, E A; Goncharova, N P; Valuev, V A

    2006-01-01

    Experimental results were compared with data of cutaneous electro-gastroenterography and USI of the gastrointestinal tract in human subjects at different tilt angles and after different periods of tilting. It was shown that increased GIT electrical activity in tilted subjects before meal is representative of increasing intracavetary contents of the stomach and small intestine. More intensive electrical activity results from elevation of the GIT tone and peristalsis. Extension of tilt duration raises GIT tone and peristalsis and, consequently, stimulates the GIT electrical activity. Further increase of the tilt angle suppresses evacuation and, therefore, the electrical activity Analysis of the results allows conclusion that increased parameters of the total energy of GIT electrical potentials are reflective of elevated tone of GIT walls, whereas elongation of the potential peaks envelope implies activation of peristalsis.

  3. Assessment of lumbar intervertebral disc glycosaminoglycan content by gadolinium-enhanced MRI before and after 21-days of head-down-tilt bedrest.

    Directory of Open Access Journals (Sweden)

    Timmo Koy

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

  4. 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

  5. Clinical problems of multiple primary cancers including head and neck cancers. From the viewpoint of radiotherapy

    International Nuclear Information System (INIS)

    Nishio, Masamichi; Myojin, Miyako; Nishiyama, Noriaki; Taguchi, Hiroshi; Takagi, Masaru; Tanaka, Katsuhiko

    2003-01-01

    A total of 2144 head and neck cancers were treated by radiotherapy at the National Sapporo Hospital between 1974 and 2001. Of these, 313 (14.6%) were found to have other primary cancers besides head and neck cancer, in which double cancers were 79% and triple or more cancers were 21%. Frequency according to primary site of the first head and neck cancer was oral cavity: 107/603 (17.7%), epipharynx cancer: 7/117 (6.0%), oropharyngeal cancer: 63/257 (24.5%), hypopharyngeal cancer: 65/200 (32.5%), laryngeal cancer: 114/558 (20.4%), and nose/paranasal sinus: 4.9% respectively. Esophageal cancer, head and neck cancer, lung cancer and gastric cancer were very frequent as other primary sites combined with the head and neck. The first onset region was the head and neck in 233 out of 313 cases with multiple primary cancers. The five-year survival rate from the onset of head and neck cancers is 52%, 10-year: 30%, and 5-year cause-specific survival rate 82%, and 10-year: 78%, respectively. The treatment possibilities in multiple primary cancers tend to be limited because the treatment areas are sometimes overlapped. New approaches to the treatment of multiple primary cancers should be considered in the future. (author)

  6. Clinical and structural features of sperm head vacuoles in men included in the in vitro fertilization programme.

    Science.gov (United States)

    Fekonja, Nina; Štrus, Jasna; Tušek Žnidarič, Magda; Knez, Katja; Vrtacnik Bokal, Eda; Verdenik, Ivan; Virant-Klun, Irma

    2014-01-01

    The human sperm head vacuoles and their role in male infertility are still poorly understood. The aim of this study was to identify the clinical and ultrastructural features of human sperm head vacuoles in men included in the in vitro fertilization programme: men with normal (normozoospermia) and impaired sperm morphology (teratozoospermia). The sperm samples were observed under 6000-time magnification using motile sperm organelle morphology examination (MSOME). The proportion of sperm with head vacuoles was evaluated and related to the outcome of in vitro fertilization. The sperm of men with impaired sperm morphology was characterized by a higher proportion of sperm head vacuoles. The sperm head vacuoles were related to impaired semen quality (sperm concentration, motility, and morphology) but were not influenced by male factors (semen volume, height, age, weight, or body mass index). Moreover, sperm head vacuoles were related to impaired fertilization rate merely after classical in vitro fertilization (IVF), while there was no relation to pregnancy. In a subgroup of men, the sperm was fixed and observed by transmission electron microscopy (TEM). The ultrastructural study revealed that sperm head vacuoles are large nuclear indentations of various sizes and positions, packed with membranous material organized in membrane whorls (MW).

  7. Effect of tilting on oxygenation in newborn infants.

    Science.gov (United States)

    Thoresen, M; Cowan, F; Whitelaw, A

    1988-01-01

    Transcutaneous (tc) PO2 in newborn infants increased on head up tilting (median increase 0.5 kPa at term, 1.0 kPa preterm). Head down tilting was associated with an equivalent fall in tcPO2. There was no change in tcPCO2. Tilting of infants mechanically ventilated for respiratory distress syndrome or surgery produced no consistent change in PO2. PMID:3128187

  8. 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.

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

    Science.gov (United States)

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

    2018-03-01

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

  10. Perception of tilt (somatogravic illusion) in response to sustained linear acceleration during space flight

    Science.gov (United States)

    Clement, G.; Moore, S. T.; Raphan, T.; Cohen, B.

    2001-01-01

    During the 1998 Neurolab mission (STS-90), four astronauts were exposed to interaural and head vertical (dorsoventral) linear accelerations of 0.5 g and 1 g during constant velocity rotation on a centrifuge, both on Earth and during orbital space flight. Subjects were oriented either left-ear-out or right-ear-out (Gy centrifugation), or lay supine along the centrifuge arm with their head off-axis (Gz centrifugation). Pre-flight centrifugation, producing linear accelerations of 0.5 g and 1 g along the Gy (interaural) axis, induced illusions of roll-tilt of 20 degrees and 34 degrees for gravito-inertial acceleration (GIA) vector tilts of 27 degrees and 45 degrees , respectively. Pre-flight 0.5 g and 1 g Gz (head dorsoventral) centrifugation generated perceptions of backward pitch of 5 degrees and 15 degrees , respectively. In the absence of gravity during space flight, the same centrifugation generated a GIA that was equivalent to the centripetal acceleration and aligned with the Gy or Gz axes. Perception of tilt was underestimated relative to this new GIA orientation during early in-flight Gy centrifugation, but was close to the GIA after 16 days in orbit, when subjects reported that they felt as if they were 'lying on side'. During the course of the mission, inflight roll-tilt perception during Gy centrifugation increased from 45 degrees to 83 degrees at 1 g and from 42 degrees to 48 degrees at 0.5 g. Subjects felt 'upside-down' during in-flight Gz centrifugation from the first in-flight test session, which reflected the new GIA orientation along the head dorsoventral axis. The different levels of in-flight tilt perception during 0.5 g and 1 g Gy centrifugation suggests that other non-vestibular inputs, including an internal estimate of the body vertical and somatic sensation, were utilized in generating tilt perception. Interpretation of data by a weighted sum of body vertical and somatic vectors, with an estimate of the GIA from the otoliths, suggests that

  11. 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

  12. Injuries in recreational curling include head injuries and may be prevented by using proper footwear

    Directory of Open Access Journals (Sweden)

    D. K. Ting

    2015-04-01

    Full Text Available Introduction: Our study examines a recreational curling population to describe patterns of injury occurrence, estimate risk of injury and to gauge attitudes towards equipment-based prevention strategies. Methods: In a retrospective case series, we queried the Canadian Hospitals Injury Reporting and Prevention Program (CHIRPP, a national injury surveillance database, for curling injuries entered between 1993 and 2011. Kingston General Hospital and Hotel Dieu Hospital provide the two Kingston, Ontario, sites for emergency department (ED care and participate in CHIRPP. Each retrieved entry underwent a chart review. A secondary survey was mailed to select individuals who had experienced curling injuries to solicit details on their injury and attitudes towards equipment to prevent injury. We used descriptive statistics for rates and proportions. Results: Over 90% of acute curling injuries resulted from a fall, and 31.7% were head impacts. We found that acute injuries requiring ED presentation occur at a rate of approximately 0.17 per 1000 athlete-exposures (95% CI: 0.12–0.22. The secondary survey was completed by 54% of potential respondents. Of survey respondents, 41.3% attributed their fall to a lack of proper footwear and 73.5% of respondents agreed with mandatory sport-specific footwear as a prevention strategy, but only 8% agreed with mandatory helmet wear. Conclusions: Although curling injuries requiring medical care are not common, head injuries make up a large proportion. Mandated use of appropriate footwear appears to be the most effective prevention strategy, as well as the measure deemed most acceptable by players.

  13. Tilt Table Test

    Science.gov (United States)

    ... test may also be appropriate to investigate the cause of fainting if you've fainted only once, but another ... recommend a tilt table test to evaluate the cause of syncope. A tilt table test may also be recommended ...

  14. 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.

  15. 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

  16. Abnormal Tilt Perception During Centrifugation in Patients with Vestibular Migraine.

    Science.gov (United States)

    Wang, Joanne; Lewis, Richard F

    2016-06-01

    Vestibular migraine (VM), defined as vestibular symptoms caused by migraine mechanisms, is very common but poorly understood. Because dizziness is often provoked in VM patients when the semicircular canals and otolith organs are stimulated concurrently (e.g., tilting the head relative to gravity), we measured tilt perception and eye movements in patients with VM and in migraine and normal control subjects during fixed-radius centrifugation, a paradigm that simultaneously modulates afferent signals from the semicircular canals and otoliths organs. Twenty-four patients (8 in each category) were tested with a motion paradigm that generated an inter-aural centrifugal force of 0.36 G, resulting in a 20° tilt of the gravito-inertial force in the roll plane. We found that percepts of roll tilt developed slower in VM patients than in the two control groups, but that eye movement responses, including the shift in the eye's rotational axis, were equivalent in all three groups. These results demonstrate a change in vestibular perception in VM that is unaccompanied by changes in vestibular-mediated eye movements and suggest that either the brain's integration of canal and otolith signals or the dynamics of otolith responses are aberrant in patients with VM.

  17. A tilting wind tunnel for fire behavior studies

    Science.gov (United States)

    David R. Weise

    1994-01-01

    The combined effects of wind velocity and slope on wildland fire behavior can be studied in the laboratory using a tilting wind tunnel. The tilting wind tunnel requires a commercially available fan to induce wind and can be positioned to simulate heading and backing fires spreading up and down slope. The tunnel is portable and can be disassembled for transport using a...

  18. Tilting a Wobbly Chair

    Science.gov (United States)

    Cross, Rod

    2017-01-01

    If a small object is placed under the front leg of a chair, the chair tilts backwards. If the object is placed under a rear leg, the chair tilts sideways. The effect is surprising but can be analysed in terms of elementary physics.

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

    Science.gov (United States)

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

    2000-01-01

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

  20. Ocular tilt reaction due to a cerebellar hemorrhage.

    Science.gov (United States)

    Tsuda, Hiromasa; Tanaka, Kozue

    2014-01-01

    A 78-year-old man with essential hypertension abruptly developed complete ocular tilt reaction (OTR) which consisted of concomitant skew deviation with left hypertropia, extorsion of the right eye and intorsion of the left, and rightward head tilt. Cranial computed tomography demonstrated a localized cerebellar hemorrhage involving the left nodulus. The patient became asymptomatic within two weeks. This is a first reported case of complete OTR due to a cerebellar hemorrhage. Concomitant skew deviation is a common symptom of cerebellar lesions. Moreover, unilateral damage to the utricular pathway due to involvement of the left nodulus might cause rightward conjugate ocular torsion and rightward head tilt.

  1. 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.

  2. Posture of the head and pharyngeal swallowing

    International Nuclear Information System (INIS)

    Ekberg, O.

    1986-01-01

    Closure of the laryngeal vestibule during swallowing is important for protection of the airways. The present investigation included 53 patients with dysphagia examined cineradiographically with the head held in resting posture, flexion and extension. The ability to protect the airways by the downward movement of the epiglottis and by obliteration of the laryngeal vestibule was studied in different postures of the head. Of 35 patients with normal laryngeal obliteration with the head in resting position 10 showed a defective closure at swallowing in extension. In 18 patients with defective closure of the laryngeal vestibule in resting position 9 were improved on flexion and two on extension of the head. In one patient with defectie closure of the laryngeal vestibule in resting position swallowing in flexion showed an aggravated dysfunction. In our other patients the defective closure became more marked on extension. Four patients had less effective downward movement of the epiglottis with the head in extension. Of 10 patients with defective epiglottic movement with the head in resting position two were improved on tilting the head forwards. The results show that the position of the head influences the closure of the airways during swallowing. Patients with defective protection of the laryngeal vestibule should be instructed to swallow with the head tilted forwards. (orig.)

  3. Posture of the head and pharyngeal swallowing

    Energy Technology Data Exchange (ETDEWEB)

    Ekberg, O.

    Closure of the laryngeal vestibule during swallowing is important for protection of the airways. The present investigation included 53 patients with dysphagia examined cineradiographically with the head held in resting posture, flexion and extension. The ability to protect the airways by the downward movement of the epiglottis and by obliteration of the laryngeal vestibule was studied in different postures of the head. Of 35 patients with normal laryngeal obliteration with the head in resting position 10 showed a defective closure at swallowing in extension. In 18 patients with defective closure of the laryngeal vestibule in resting position 9 were improved on flexion and two on extension of the head. In one patient with defectie closure of the laryngeal vestibule in resting position swallowing in flexion showed an aggravated dysfunction. In our other patients the defective closure became more marked on extension. Four patients had less effective downward movement of the epiglottis with the head in extension. Of 10 patients with defective epiglottic movement with the head in resting position two were improved on tilting the head forwards. The results show that the position of the head influences the closure of the airways during swallowing. Patients with defective protection of the laryngeal vestibule should be instructed to swallow with the head tilted forwards.

  4. 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.

  5. The sagittal pelvic tilt index as a criterion in the evaluation of spondylolisthesis. Preliminary observations.

    Science.gov (United States)

    Schwab, F J; Farcy, J P; Roye, D P

    1997-07-15

    Radiographic analysis of a pediatric population with spondylolisthesis was performed to examine sagittal plane pelvic rotation and degree of slip over time. To determine whether the degree of standing sagittal offset of L5 with respect to the acetabulum correlated with slip progression and symptoms. The natural history of isthmic spondylolisthesis remains unclear. Attempts to predict slip progression in the clinical setting, and thus the possible need for eventual surgical intervention, remain imprecise. Predicting slip progression based on sagittal alignment of the L5 vertebra with respect to the acetabulum has been proposed by some investigators. Fifty-two children and adolescents were followed clinically and radiographically for an average of 5.6 years. Serial lateral standing radiographs that included the hips and lumbar spine were measured to compute a sagittal pelvic tilt index. The latter value is a ratio of relative distances from the center of S2 to the projection of L5 and the center of the femoral heads on the horizontal. Of the 52 patients studied, 38 have remained asymptomatic without significant slip progression or change in sagittal pelvic tilt index ratio. Of the original group, 13 patients had significant symptoms and revealed a decrease in the sagittal pelvic tilt index over time. Eight of the 13 stabilized at the end of adolescence, whereas 5 had continued decrease in the sagittal pelvic tilt index ratio. These five required operative treatment for pain and progressive slip. The sagittal pelvic tilt index gives the examiner an objective measure of the stability of the lumbosacral junction by quantifying the relationship between S2, the center of the hip, and L5. A decreasing sagittal pelvic tilt index ratio in this preliminary series correlated with slip progression and risk of conservative treatment failure, whereas those patients with a stable sagittal pelvic tilt index did not progress and remained clinically asymptomatic.

  6. Rigidity of tilting modules

    DEFF Research Database (Denmark)

    Haahr Andersen, Henning; Kaneda, Masaharu

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

  7. Hemodynamic and symptomatic effects of acute interventions on tilt in patients with postural tachycardia syndrome

    Science.gov (United States)

    Gordon, V. M.; Opfer-Gehrking, T. L.; Novak, V.; Low, P. A.

    2000-01-01

    A variety of approaches have been used to alleviate symptoms in postural tachycardia syndrome (POTS). Drugs reported to be of benefit include midodrine, propranolol, clonidine, and phenobarbital. Other measures used include volume expansion and physical countermaneuvers. These treatments may influence pathophysiologic mechanisms of POTS such as alpha-receptor dysfunction, beta-receptor supersensitivity, venous pooling, and brainstem center dysfunction. The authors prospectively studied hemodynamic indices and symptom scores in patients with POTS who were acutely treated with a variety of interventions. Twenty-one subjects who met the criteria for POTS were studied (20 women, 1 man; mean age, 28.7 +/- 6.8 y; age range, 14-39 y). Patients were studied with a 5-minute head-up tilt protocol, ECG monitoring, and noninvasive beat-to-beat blood pressure monitoring, all before and after the administration of an intervention (intravenous saline, midodrine, propranolol, clonidine, or phenobarbital). The hemodynamic indices studied were heart rate (ECG) and systolic, mean, and diastolic blood pressure. Patients used a balanced verbal scale to record any change in their symptoms between the tilts. Symptom scores improved significantly after the patients received midodrine and saline. Midodrine and propranolol reduced the resting heart rate response to tilt (p midodrine and intravenous saline are effective in decreasing symptoms on tilt in patients with POTS when given acutely. Effects of treatments on heart rate and blood pressure responses generally reflected the known pharmacologic mechanisms of the agents.

  8. Role of Baroreflex Sensitivity in Predicting Tilt Training Response in Patients with Neurally Mediated Syncope.

    Science.gov (United States)

    Chun, Kwang Jin; Yim, Hye Ran; Park, Jungwae; Park, Seung Jung; Park, Kyoung Min; On, Young Keun; Kim, June Soo

    2016-03-01

    An association between baroreflex sensitivity (BRS) and the response to tilt training has not been reported in patients with neurally mediated syncope (NMS). This study sought to investigate the role of BRS in predicting the response to tilt training in patients with NMS. We analyzed 57 patients who underwent tilt training at our hospital. A responder to tilt training was defined as a patient with three consecutive negative responses to the head-up tilt test (HUT) during tilt training. After tilt training, 52 patients (91.2%) achieved three consecutive negative responses to the HUT. In the supine position before upright posture during the first session of tilt training for responders and non-responders, the mean BRS was 18.17 ± 10.09 ms/mm Hg and 7.99 ± 5.84 ms/mm Hg (p=0.008), respectively, and the frequency of BRS ≥ 8.945 ms/mm Hg was 45 (86.5%) and 1 (20.0%; p=0.004), respectively. Age, male gender, frequency of syncopal events before HUT, type of NMS, phase of positive HUT, total number of tilt training sessions, and mean time of tilt training did not differ between the study groups. In the multivariate analysis, BRS training. The BRS value in the supine position could be a predictor for determining the response to tilt training in patients with NMS who are being considered for inpatient tilt training.

  9. Oral rehabilitation with tilted dental implants: A metaanalysis

    Science.gov (United States)

    Peñarrocha-Oltra, David; Candel-Marti, Eugenia; Peñarrocha-Diago, Maria

    2012-01-01

    Objective: To compare the course of patients treated with tilted implants versus those treated conventionally with axial implants, analyzing the success rate and marginal bone loss. Material and Methods: A PubMed search was made using the key words “tilted implants”, “angled implants”, “angulated implants”, “inclined implants” and “maxillary atrophy.” A review was made of the articles published between 1999-2010. The inclusion criteria were the use of tilted implants, clinical series involving at least 10 patients, and a minimum follow-up of 12 months after prosthetic loading. The exclusion criteria were isolated clinical cases, studies with missing data, and publications in languages other than English or Spanish. The metaanalysis finally included 13 articles: 7 retrospective studies and 6 prospective studies. Results: On analyzing the success rate in the retrospective studies, two reported a higher success rate with tilted implants; one a higher success rate with axial implants; and two reported similar success rates with both implants. On analyzing the success rate in the prospective studies, two reported a higher success rate with tilted implants; two a higher success rate with axial implants; and two reported similar success rates with both implants. On examining marginal bone loss, three studies reported greater bone loss with axial implants and one with tilted implants. Conclusions: There was no evidence of differences in success rate between tilted and axial implants in either the prospective or retrospective studies subjected to review. The marginal bone loss observed with the tilted and axial implants likewise proved very similar. It thus can be deduced that tilted implants exhibit the same evolutive behavior as axial implants. Key words:Axial implants, tilted implants, maxillary atrophy, tilted implants. PMID:22322494

  10. Importance to include the term superficial musculoaponeurotic system in medical subject headings and in the international anatomical nomenclature.

    Science.gov (United States)

    Ferreira, Lydia Massako; Locali, Rafael Fagionato; Lapin, Guilherme Abbud Franco; Hochman, Bernardo

    2011-06-01

    To investigate the relevance of the term superficial musculoaponeurotic system (SMAS) and demonstrate that this term is important enough to be added to the MeSH database and listed in International Anatomical Nomenclature. Terms related to SMAS were selected from original articles retrieved from the ISI Web of Science and MEDLINE (PubMed) databases. Groups of terms were created to define a search strategy with high-sensitivity and restricted to scientific periodicals devoted to plastic surgery. This study included articles between January 1996 and May 2009, whose titles, abstracts, and keywords were searched for SMAS-related terms and all occurrences were recorded. A total of 126 original articles were retrieved from the main periodicals related to plastic surgery in the referred databases. Of these articles, 51.6% had SMAS-related terms in the abstract only, and 25.4% had SMAS-related terms in both the title and abstract. The term 'superficial musculoaponeurotic system' was present as a keyword in 19.8% of the articles. The most frequent terms were 'SMAS' (71.4%) and superficial musculoaponeurotic system (62.7%). The term SMAS refers to a structure relevant enough to start a discussion about indexing it as a keyword and as an official term in Terminologia Anatomica: International Anatomical Terminology.

  11. Tibia Bone Microvascular Flow Dynamics as Compared to Anterior Tibial Artery Flow During Body Tilt.

    Science.gov (United States)

    Becker, Rachel L; Siamwala, Jamila H; Macias, Brandon R; Hargens, Alan R

    2018-04-01

    We compared microvascular and macrovascular blood flows of the tibia and anterior tibial artery during graded whole-body tilt. We hypothesized equal responses for bone microvascular and macrovascular blood flows during varying angles of tilt. There were 18 volunteers who were randomly positioned in the following postures: supine, 15° head-up tilt, 6° head-up tilt, 6° head-down tilt, and 15° head-down tilt using an inversion table with reference to seated posture (baseline control). Ultrasonography quantified anterior tibial arterial diameter and peak systolic velocity, enabling calculation of macrovascular blood flow to the tibia. Tibial bone microvascular blood flow was measured noninvasively using photoplethysmography in the same leg. Transitioning from a seated position to a supine position, macrovascular blood flow did not change significantly (1.81 ± 1.18 to 2.80 ± 1.74cm 3 · s-1). However, bone microvascular flow increased significantly (0.36 ± 0.23 to 1.11 ± 0.79 V) from the seated to the supine position. Transitioning from a seated posture to 15° head-down tilt, both arterial macrovascular and bone microvascular flows increased significantly (1.81 ± 1.18 to 3.32 ± 2.08 cm3 · s-1 and 0.36 ± 0.23 V to 2.99 ± 2.71 V, respectively). The normalized flow for microvascular blood flow as a function of body tilt was significantly greater than that for macrovascular blood flow at 6° and 15° head-down tilt. These data do not support our hypothesis that bone microvascular flow and arterial macrovascular flow share equal responses to altered body tilt. Therefore, for a given decrease in local blood pressure in the leg with head-down body tilt, the magnitude of increase in blood flow is greater in the microcirculation as compared to the feeding artery.Becker RL, Siamwala JH, Macias BR, Hargens AR. Tibia bone microvascular flow dynamics as compared to anterior tibial artery flow during body tilt. Aerosp Med Hum Perform. 2018; 89(4):357-364.

  12. Effects of Head Position on Perception of Gravity in Vestibular Neuritis and Lateral Medullary Infarction

    Directory of Open Access Journals (Sweden)

    Sung-Hee Kim

    2018-02-01

    Full Text Available ObjectiveInternal representation of gravity can be quantified by measuring the subjective visual vertical (SVV. Modulation of verticality perception during head tilts may be perturbed in vestibular disorders causing SVV tilts in the upright head position. This study aimed to determine the influence of head tilts on the estimation of SVV in acute vestibular disorders.MethodsWe measured the SVV in 37 patients with acute vestibular symptoms due to unilateral vestibular neuritis (VN (n = 28 and lateral medullary infarction (LMI (n = 9. Measurements of the SVV were performed under head upright, head tilt 30° and 60° in each direction. Seventeen normal subjects served as the control.ResultsIn controls, head tilt of 30° produced a contraversive shift of the SVV (the E-effect, and head tilt of 60° generated an ipsiversive shift (the A-effect. Patients with VN showed only the A-effect irrespective of the direction and amplitude of head tilt. Patients with LMI could estimate earth verticality accurately during head tilts. Patients with VN during the recovery phase showed the patterns of SVV modulation similar to those observed in the controls either with head upright or tilted.ConclusionGiven the absence of the E-effect in acute VN, the peripheral otolithic inputs appear to be essential in the perception of earth vertical during small static head tilts.

  13. Effects of Head Position on Perception of Gravity in Vestibular Neuritis and Lateral Medullary Infarction.

    Science.gov (United States)

    Kim, Sung-Hee; Kim, Ji-Soo

    2018-01-01

    Internal representation of gravity can be quantified by measuring the subjective visual vertical (SVV). Modulation of verticality perception during head tilts may be perturbed in vestibular disorders causing SVV tilts in the upright head position. This study aimed to determine the influence of head tilts on the estimation of SVV in acute vestibular disorders. We measured the SVV in 37 patients with acute vestibular symptoms due to unilateral vestibular neuritis (VN) ( n  = 28) and lateral medullary infarction (LMI) ( n  = 9). Measurements of the SVV were performed under head upright, head tilt 30° and 60° in each direction. Seventeen normal subjects served as the control. In controls, head tilt of 30° produced a contraversive shift of the SVV (the E-effect), and head tilt of 60° generated an ipsiversive shift (the A-effect). Patients with VN showed only the A-effect irrespective of the direction and amplitude of head tilt. Patients with LMI could estimate earth verticality accurately during head tilts. Patients with VN during the recovery phase showed the patterns of SVV modulation similar to those observed in the controls either with head upright or tilted. Given the absence of the E-effect in acute VN, the peripheral otolithic inputs appear to be essential in the perception of earth vertical during small static head tilts.

  14. Source to Accretion Disk Tilt

    OpenAIRE

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

    2010-01-01

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

  15. Motion sickness on tilting trains.

    Science.gov (United States)

    Cohen, Bernard; Dai, Mingjia; Ogorodnikov, Dmitri; Laurens, Jean; Raphan, Theodore; Müller, Philippe; Athanasios, Alexiou; Edmaier, Jürgen; Grossenbacher, Thomas; Stadtmüller, Klaus; Brugger, Ueli; Hauser, Gerald; Straumann, Dominik

    2011-11-01

    Trains that tilt on curves can go faster, but passengers complain of motion sickness. We studied the control signals and tilts to determine why this occurs and how to maintain speed while eliminating motion sickness. Accelerometers and gyros monitored train and passenger yaw and roll, and a survey evaluated motion sickness. The experimental train had 3 control configurations: an untilted mode, a reactive mode that detected curves from sensors on the front wheel set, and a predictive mode that determined curves from the train's position on the tracks. No motion sickness was induced in the untilted mode, but the train ran 21% slower than when it tilted 8° in either the reactive or predictive modes (113 vs. 137 km/h). Roll velocities rose and fell faster in the predictive than the reactive mode when entering and leaving turns (0.4 vs. 0.8 s for a 4°/s roll tilt, P<0.001). Concurrently, motion sickness was greater (P<0.001) in the reactive mode. We conclude that the slower rise in roll velocity during yaw rotations on entering and leaving curves had induced the motion sickness. Adequate synchronization of roll tilt with yaw velocity on curves will reduce motion sickness and improve passenger comfort on tilting trains.

  16. Photovoltaic Modules: Effect of Tilt Angle on Soiling

    Science.gov (United States)

    Cano, Jose

    2011-12-01

    Photovoltaic (PV) systems are one of the next generation's renewable energy sources for our world energy demand. PV modules are highly reliable. However, in polluted environments, over time, they will collect grime and dust. There are also limited field data studies about soiling losses on PV modules. The study showed how important it is to investigate the effect of tilt angle on soiling. The study includes two sets of mini-modules. Each set has 9 PV modules tilted at 0, 5, 10, 15, 20, 23, 30, 33 and 40°. The first set called "Cleaned" was cleaned every other day. The second set called "Soiled" was never cleaned after the first day. The short circuit current, a measure of irradiance, and module temperature was monitored and recorded every two minutes over three months (January-March 2011). The data were analyzed to investigate the effect of tilt angle on daily and monthly soiling, and hence transmitted solar insolation and energy production by PV modules. The study shows that during the period of January through March 2011 there was an average loss due to soiling of approximately 2.02% for 0° tilt angle. Modules at tilt angles 23° and 33° also have some insolation losses but do not come close to the module at 0° tilt angle. Tilt angle 23° has approximately 1.05% monthly insolation loss, and 33° tilt angle has an insolation loss of approximately 0.96%. The soiling effect is present at any tilt angle, but the magnitude is evident: the flatter the solar module is placed the more energy it will lose.

  17. 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.

  18. 'Sit and tilt' preparation for subscapular system free flaps.

    Science.gov (United States)

    Mark, J; Patwa, H; Costello, M S; Patil, Y

    2018-02-01

    The ablation of advanced head and neck cancer often results in large three-dimensional defects that require free tissue transfer to optimally address functional and cosmetic issues. The subscapular system is a highly versatile donor site for flaps used for head and neck reconstruction. Traditional methods of harvesting subscapular flaps require repositioning and re-preparing, which significantly increases the operative time and prevents simultaneous harvesting of the flap. This paper presents our experience of a single-stage 'sit and tilt' technique, which provides a convenient method for harvesting subscapular system free flaps without significant repositioning. This technique was used for a variety of head and neck defects, and body habitus did not seem to affect free tissue harvesting. It is hoped that utilisation of this preparation and harvesting technique will make head and neck surgeons more willing to take advantage of the subscapular system.

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

    Science.gov (United States)

    Brasser, R.; Lee, Man Hoi

    2015-11-01

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

  20. Height and Tilt Geometric Texture

    DEFF Research Database (Denmark)

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

    2009-01-01

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

  1. Predictive value of diffusion-weighted imaging without and with including contrast-enhanced magnetic resonance imaging in image analysis of head and neck squamous cell carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Noij, Daniel P., E-mail: d.noij@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands); Pouwels, Petra J.W., E-mail: pjw.pouwels@vumc.nl [Department of Physics and Medical Technology, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands); Ljumanovic, Redina, E-mail: rljumanovic@adventh.org [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands); Knol, Dirk L., E-mail: dirklknol@gmail.com [Department of Epidemiology and Biostatistics, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands); Doornaert, Patricia, E-mail: p.doornaert@vumc.nl [Department of Radiation Oncology, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands); Bree, Remco de, E-mail: r.debree@vumc.nl [Department of Otolaryngology – Head and Neck Surgery, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands); Castelijns, Jonas A., E-mail: j.castelijns@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands); Graaf, Pim de, E-mail: p.degraaf@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, Amsterdam, Noord-Holland (Netherlands)

    2015-01-15

    Highlights: • Primary tumor volume and lymph node ADC1000 are predictors of survival. • CE-T1WI does not improve the prognostic capacity of DWI. • Using CE-T1WI for ROI placement results in lower interobserver agreement. - Abstract: Objectives: To assess disease-free survival (DFS) in head and neck squamous cell carcinoma (HNSCC) treated with (chemo)radiotherapy ([C]RT). Methods: Pretreatment MR-images of 78 patients were retrospectively studied. Apparent diffusion coefficients (ADC) were calculated with two sets of two b-values: 0–750 s/mm{sup 2} (ADC{sub 750}) and 0–1000 s/mm{sup 2} (ADC{sub 1000}). One observer assessed tumor volume on T1-WI. Two independent observers assessed ADC-values of primary tumor and largest lymph node in two sessions (i.e. without and with including CE-T1WI in image analysis). Interobserver and intersession agreement were assessed with intraclass correlation coefficients (ICC) separately for ADC{sub 750} and ADC{sub 1000}. Lesion volumes and ADC-values were related to DFS using Cox regression analysis. Results: Median follow-up was 18 months. Interobserver ICC was better without than with CE-T1WI (primary tumor: 0.92 and 0.75–0.83, respectively; lymph node: 0.81–0.83 and 0.61–0.64, respectively). Intersession ICC ranged from 0.84 to 0.89. With CE-T1WI, mean ADC-values of primary tumor and lymph node were higher at both b-values than without CE-T1WI (P < 0.001). Tumor volume (sensitivity: 73%; specificity: 57%) and lymph node ADC{sub 1000} (sensitivity: 71–79%; specificity: 77–79%) were independent significant predictors of DFS without and with including CE-T1WI (P < 0.05). Conclusions: Pretreatment primary tumor volume and lymph node ADC{sub 1000} were significant independent predictors of DFS in HNSCC treated with (C)RT. DFS could be predicted from ADC-values acquired without and with including CE-T1WI in image analysis. The inclusion of CE-T1WI did not result in significant improvements in the predictive value of

  2. 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.

  3. Whole-body-MR imaging including DWIBS in the work-up of patients with head and neck squamous cell carcinoma: A feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Noij, Daniel P., E-mail: d.noij@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, PO Box 7057, 1007 MB Amsterdam (Netherlands); Boerhout, Els J., E-mail: e.boerhout@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, PO Box 7057, 1007 MB Amsterdam (Netherlands); Pieters-van den Bos, Indra C., E-mail: i.pieters@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, PO Box 7057, 1007 MB Amsterdam (Netherlands); Comans, Emile F., E-mail: efi.comans@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, PO Box 7057, 1007 MB Amsterdam (Netherlands); Oprea-Lager, Daniela, E-mail: d.oprea-lager@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, PO Box 7057, 1007 MB Amsterdam (Netherlands); Reinhard, Rinze, E-mail: r.reinhard@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, PO Box 7057, 1007 MB Amsterdam (Netherlands); Hoekstra, Otto S., E-mail: os.hoekstra@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, PO Box 7057, 1007 MB Amsterdam (Netherlands); Bree, Remco de, E-mail: r.debree@vumc.nl [Department Otolaryngology/Head and Neck Surgery, VU University Medical Center, De Boelelaan 1117, PO Box 7057, 1007 MB Amsterdam (Netherlands); Graaf, Pim de, E-mail: p.degraaf@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, PO Box 7057, 1007 MB Amsterdam (Netherlands); Castelijns, Jonas A., E-mail: j.castelijns@vumc.nl [Department of Radiology and Nuclear Medicine, VU University Medical Center, De Boelelaan 1117, PO Box 7057, 1007 MB Amsterdam (Netherlands)

    2014-07-15

    Objectives: To assess the feasibility of whole-body magnetic resonance imaging (WB-MRI) including diffusion-weighted whole-body imaging with background-body-signal-suppression (DWIBS) for the evaluation of distant malignancies in head and neck squamous cell carcinoma (HNSCC); and to compare WB-MRI findings with {sup 18}F-fluorodeoxyglucose positron emission tomography/computed tomography ({sup 18}F-FDG-PET/CT) and chest-CT. Methods: Thirty-three patients with high risk for metastatic spread (26 males; range 48–79 years, mean age 63 ± 7.9 years (mean ± standard deviation) years) were prospectively included with a follow-up of six months. WB-MRI protocol included short-TI inversion recovery and T1-weighted sequences in the coronal plane and half-fourier acquisition single-shot turbo spin-echo T2 and contrast-enhanced-T1-weighted sequences in the axial plane. Axial DWIBS was reformatted in the coronal plane. Interobserver variability was assessed using weighted kappa and the proportion specific agreement (PA). Results: Two second primary tumors and one metastasis were detected on WB-MRI. WB-MRI yielded seven clinically indeterminate lesions which did not progress at follow-up. The metastasis and one second primary tumor were found when combining {sup 18}F-FDG-PET/CT and chest-CT findings. Interobserver variability for WB-MRI was κ = 0.91 with PA ranging from 0.82 to 1.00. For {sup 18}F-FDG-PET/CT κ could not be calculated due to a constant variable in the table and PA ranged from 0.40 to 0.99. Conclusions: Our WB-MRI protocol with DWIBS is feasible in the work-up of HNSCC patients for detection and characterization of distant pathology. WB-MRI can be complementary to {sup 18}F-FDG-PET/CT, especially in the detection of non {sup 18}F-FDG avid second primary tumors.

  4. Tilted seat position for non-ambulant individuals with neurological and neuromuscular impairment: a systematic review

    OpenAIRE

    Michael, SM; Porter, D; Pountney, TE

    2008-01-01

    Objective: To determine the effects of tilt-in-space seating on outcomes for people with neurological or neuromuscular impairment who cannot walk. Data sources: Search through electronic databases (MEDLINE, Embase, CINAHL, AMED). Discussions with researchers who are active in field. Review methods: Selection criteria included interventional studies that investigated the effects of seat tilt on outcome or observational studies that identified outcomes for those who had used tilt-in-space seati...

  5. Recording Tilt with Broadband Seismic Sensors at Erupting Volcanoes

    Science.gov (United States)

    Young, B. E.; Lees, J. M.; Lyons, J. J.

    2011-12-01

    The horizontal components of broadband seismometers are known to be susceptible to gravitational acceleration due to slow tilting, and this has been successfully exploited to assess ground deformation at many volcanoes, including Anatahan (Mariana Islands), Meakan-dake (Japan), Santiaguito (Guatemala) and Stromboli (Italy). Tilt can be estimated from seismic velocity by differentiating, scaling to remove gravity, and applying an instrument correction. The fundamental assumption in estimating tilt from broadband data is that the signal recorded is the result of tilt and not translation, thus analysis of tilt require filtering below corner frequencies of seismic instruments, where the response to tilt should be flat. However, processing techniques for deriving tilt are not uniform among researchers. Filter type and passband allowance for the processing of data sets differs from case to case, and the dominant periods of tilt signals may vary from tens to hundreds of seconds. For instance, data from Santiaguito was filtered in the 600-30s passband, while at Anatahan filters spanned 13 hours to 8 minutes. In our study, we investigate tilt from seismic data sets at Karymsky (Kamchatka, Russia), Fuego (Guatemala), Yasur (Vanuatu), and Tungurahua (Ecuador) to understand implementation and limitations of this tool. We examine the importance of filter-type distortion related to filtering on the seismic signal. For example, a comparison of time domain versus frequency domain implementation is explored using a variety of lowpass and bandpass filters. We also investigate the advantages and drawbacks of causal versus acausal filters. In a few cases tiltmeters have been co-located with broadband seismic sensors for direct comparison. Signals at Mt. St. Helens, Stromboli, Sakurajima, and Semeru show a correlation of tilt and seismic records, although records at Karymsky volcano suggest that no tilt is recorded on either instrument. We speculate that strong vent explosions exhibit

  6. New tilted-poles Wien filter with enhanced performance

    Science.gov (United States)

    Leal-Quiros, E.; Prelas, M. A.

    1989-03-01

    The Wien filter is an E×B deflecting analyzer with the electrostatic field perpendicular to the magnetostatic field. The twofold functions of the Wien filter are as an energy analyzer as well as a mass analyzer. It has very high resolution for paraxial charged-particle beams with V=E/B, the Wien velocity. Two Wien filters, a tilted-poles Wien filter, and a classical parallel-rectangular-poles Wien filter were built and tested for electrons up to 3.5 keV and protons beams of 200 eV. (The tilted-poles Wien filter is a new diagnostic developed by the authors.) The performance of the two is compared, and the tilted-poles Wien filter has superior resolution to the classical Wien filter. Both Wien filters appear to have features useful for high-temperature plasma diagnostics, including simultaneous measurement of energy and mass spectra, and high resolution.

  7. New tilted-poles Wien filter with enhanced performance

    Energy Technology Data Exchange (ETDEWEB)

    Leal-Quiros, E.; Prelas, M.A.

    1989-03-01

    The Wien filter is an E x B deflecting analyzer with the electrostatic field perpendicular to the magnetostatic field. The twofold functions of the Wien filter are as an energy analyzer as well as a mass analyzer. It has very high resolution for paraxial charged-particle beams with V = E/B, the Wien velocity. Two Wien filters, a tilted-poles Wien filter, and a classical parallel-rectangular-poles Wien filter were built and tested for electrons up to 3.5 keV and protons beams of 200 eV. (The tilted-poles Wien filter is a new diagnostic developed by the authors.) The performance of the two is compared, and the tilted-poles Wien filter has superior resolution to the classical Wien filter. Both Wien filters appear to have features useful for high-temperature plasma diagnostics, including simultaneous measurement of energy and mass spectra, and high resolution.

  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. 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.

  10. 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...

  11. 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....... However, the effectiveness in reducing excessive anterior pelvic tilt in adults is unknown. Purpose: To systematically review studies investigating the effectiveness of conservative treatment in reducing anterior pelvic tilt in adults and evaluate the quality of evidence. Materials and methods: MEDLINE...

  12. Capacitive micromachined ultrasonic transducer based tilt sensing

    Science.gov (United States)

    Yu, Hongbin; Guo, Bin; Haridas, Kuruveettil; Lin, Tsu-Hui; Hao Cheong, Jia; Lin Tsai, Ming; Boon Yee, Tack

    2012-10-01

    In this paper, a tilt sensing mechanism based on the capacitive micromachined ultrasound transducers (CMUTs) is presented. By measuring the difference in the time of flight of various pulse-echo signals from different CMUT transmitting elements to one common receiving element in the oil bath, the tilt angle of the oil surface can be determined. With the proposed device, the maximum tilt angles of 20° and 28° have been measured in the clockwise and counterclockwise directions, respectively, and the difference between the measured and the theoretical values of the tilt angle was found to be within 0.05° during the whole test.

  13. On the simplifications for the thermal modeling of tilting-pad journal bearings under thermoelastohydrodynamic regime

    DEFF Research Database (Denmark)

    Cerda Varela, Alejandro Javier; Fillon, Michel; Santos, Ilmar

    2012-01-01

    The relevance of calculating accurately the oil film temperature build up when modeling tilting-pad journal bearings is well established within the literature on the subject. This work studies the feasibility of using a thermal model for the tilting-pad journal bearing which includes a simplified...

  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. Radiochemotherapy including cisplatin alone versus cisplatin + 5-fluorouracil for locally advanced unresectable stage IV squamous cell carcinoma of the head and neck

    International Nuclear Information System (INIS)

    Tribius, Silke; Kilic, Yasemin; Kronemann, Stefanie; Schroeder, Ursula; Hakim, Samer; Schild, Steven E.; Rades, Dirk

    2009-01-01

    Background and purpose: the optimal radiochemotherapy regimen for advanced head-and-neck cancer is still debated. This nonrandomized study compares two cisplatin-based radiochemotherapy regimens in 128 patients with locally advanced unresectable stage IV squamous cell carcinoma of the head and neck (SCCHN). Patients and methods: concurrent chemotherapy consisted of either two courses cisplatin (20 mg/m 2 /d1-5 + 29-33; n = 54) or two courses cisplatin (20 mg/m 2 /d1-5 + 29-33) + 5-fluorouracil (5-FU; 600 mg/m 2 /d1-5 + 29-33; n = 74). Results: at least one grade 3 toxicity occurred in 25 of 54 patients (46%) receiving cisplatin alone and in 52 of 74 patients (70%) receiving cisplatin + 5-FU. The latter regimen was particularly associated with increased rates of mucositis (p = 0.027) and acute skin toxicity (p = 0.001). Seven of 54 (13%) and 20 of 74 patients (27%) received only one chemotherapy course due to treatment-related acute toxicity. Late toxicity in terms of xerostomia, neck fibrosis, skin toxicity, and lymphedema was not significantly different. The 2-year locoregional control rates were 67% after cisplatin alone and 52% after cisplatin + 5-FU (p = 0.35). The metastases-free survival rates were 79% and 69%, respectively (p = 0.65), and the overall survival rates 70% and 51%, respectively (p = 0.10). On multivariate analysis, outcome was significantly associated with performance status, T-category, N-category, hemoglobin level prior to radiotherapy, and radiotherapy break > 1 week. Conclusion: two courses of fractionated cisplatin (20 mg/m 2 /day) alone appear preferable, as this regimen resulted in similar outcome and late toxicity as two courses of cisplatin + 5-FU, but in significantly less acute toxicity. (orig.)

  16. 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

  17. Lake-tilting investigations in southern Sweden

    International Nuclear Information System (INIS)

    Paasse, T.

    1996-04-01

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

  18. Lake-tilting investigations in southern Sweden

    Energy Technology Data Exchange (ETDEWEB)

    Paasse, T. [Sveriges Geologiska Undersoekning, Goeteborg (Sweden)

    1996-04-01

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

  19. 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.

  20. 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

  1. Modulation of Internal Estimates of Gravity during and after Prolonged Roll-Tilts

    Science.gov (United States)

    Tarnutzer, Alexander A.; Bertolini, Giovanni; Bockisch, Christopher J.; Straumann, Dominik; Marti, Sarah

    2013-01-01

    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 (23-56yo) repetitively adjusted a luminous arrow to the SVV over periods of 5min while upright, roll-tilted (±45°, ±90°), and immediately after returning to upright. Significant (p<0.05) drifts (median absolute drift-amplitude: 10°/5min) 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: 71sec) 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 adaptation, most

  2. 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...

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

    Directory of Open Access Journals (Sweden)

    Marian L Dale

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

  4. A new measurement for posterior tilt predicts reoperation in undisplaced femoral neck fractures: 113 consecutive patients treated by internal fixation and followed for 1 year

    DEFF Research Database (Denmark)

    Palm, Henrik; Gosvig, Kasper; Krasheninnikoff, Michael

    2009-01-01

    posterior tilt was an accurate predictor of failure (p = 0.002). 14/25 of posteriorly tilted fractures > or = 20 degrees were reoperated, as compared to 12/88 of fractures with less tilt (p analysis including sex, age, ASA score, cognitive function, new mobility...

  5. 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.

  6. Experimental studies of octahedral tilting in perovskites

    International Nuclear Information System (INIS)

    Howard, C.J.; Kennedy, B.J.; Chakoumakos, B.C.

    1999-01-01

    Full text: Structures of the perovskite family, ABX 3 , have interested crystallographers over many years, and continue to attract attention on account of their fascinating electrical and magnetic properties, and their significance in the earth sciences. The ideal perovskite (cubic) is a particularly simple structure, but also a demanding one, since aside from the lattice parameter there are no variable parameters in the structure. Consequently, the majority of perovskite structures show departures from the ideal, the most common distortion being the comer-linked tilting of the practically rigid BX 6 octahedral units. Following a group theoretical study in 1997, a number of experimental investigations of octahedral tilting have been undertaken in 1998, and these are reported in this presentation. The studies are of the perovskites, SrZrO 3 , SrHfO 3 , CaTiO 3 , NaTaO 3 and LaGaO 3 . In each case, the crystal structures have been followed at high temperatures, with particular attention being paid to temperature regimes in which only the simplest octahedral tilt (only one tilt axis) pertains. Neutron powder diffraction patterns have been recorded on the medium/high resolution diffractometer installed at beam port HB4 at the High Flux Isotope Reactor, at the Oak Ridge National Laboratory. Crystal structures have been refined by the Rietveld method, and angles of tilt of the oxygen octahedra derived from the atomic position parameters. Each of the first four perovskites listed above transforms from tetragonal (with a single tilt axis) to cubic, and in each case, as far as can be determined from our measurements, the tilt angle in the tetragonal phase decreases continuously towards zero. There are interesting differences, however, in the functional form of this variation. The LaGaO 3 transforms at modest temperature to a rhombohedral phase, also characterised by a single tilt axis, but though the tilt angle decreases slowly with increasing temperature, the sample

  7. 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.

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

    International Nuclear Information System (INIS)

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

    2005-01-01

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

  9. Is HEADS in our heads?

    DEFF Research Database (Denmark)

    Boisen, Kirsten A; Hertz, Pernille Grarup; Blix, Charlotte

    2016-01-01

    BACKGROUND: Outpatient clinic visits are a window of opportunity to address health risk behaviors and promote a healthier lifestyle among young people. The HEADS (Home, Education, Eating, Activities, Drugs [i.e. substance use including tobacco, alcohol, and illegal drugs], Sexuality [including...... contraception], Safety, Self-harm) interview is a feasible way of exploring health risk behaviors and resilience. OBJECTIVE: The purpose of this study was to evaluate how often HEADS topics were addressed according to young patients and staff in pediatric and adult outpatient clinics. METHODS: We conducted...

  10. Surgical outcomes of intermittent exotropia associated with concomitant hypertropia including simulated superior oblique palsy after horizontal muscles surgery only.

    Science.gov (United States)

    Cho, Y A; Kim, S-H

    2007-12-01

    To investigate the clinical features and obtain guideline of treatment in intermittent exotropia associated with hypertropia including simulated superior oblique palsy. We retrospectively reviewed the charts of 93 patients of intermittent exotropia aligned with horizontal muscle surgery only, who showed hypertropia more than 2 PD in primary gaze before surgery and disappeared after surgery. They showed forveal extorsion and dysfunction of oblique muscles of 2+ or less and positive Bielschowsky head tilt test. The postoperative changes of deviation angle were analysed at postoperative 1 day, 6 months, and 1 year. Average amount of distant horizontal deviation in primary gaze was 32.3+/-9.58 (25-53) PD, hypertropia was 3.50+/-2.52 (2-14) PD. Average vertical deviation of ipsilateral (hypertropic eye) side was 8.8+/-4.63 PD and contralateral (hypotrophic eye) side was 4.0+/-4.77 PD in Bielschowsky head tilt test. Hypertropic eye was accorded with exotropic eye in 53.4%. After horizontal surgery, the amount of hypertropia was 1.2 PD at postoperative 1 day. On Bielschowsky head tilt test, hypertropia was almost eliminated showing 0.6 PD on the ipsilateral side and 0.2 PD on the contralateral eye at 1 month. This state was maintained up to postoperative 1 year. Small amount of hypertropia up to 14 PD in intermittent exotropia could be disappeared with horizontal muscle surgery only. However, careful examinations for head tilt history, fovea extorsion, oblique dysfunction, and Maddox rod test should be preceded to rule out true superior oblique palsy.

  11. Conservative treatment of excessive anterior pelvic tilt

    DEFF Research Database (Denmark)

    Brekke, Anders Falk

    quality by two reviewers using Cochrane Collaboration’s tool for assessing risk of bias in RCT’s and the ROBINS-I tool (Risk Of Bias In Non-randomized Studies - of interventions). Data was synthesized qualitatively. The GRADE approach was used to determine the overall quality of the evidence. PROSPERO...... treatment may reduce anterior pelvis tilt and reduce symptoms in relation to faulty posture. Keywords: pelvis, anterior tilt, anteversion, posture...

  12. Head and Neck Cancer

    Science.gov (United States)

    Head and neck cancer includes cancers of the mouth, nose, sinuses, salivary glands, throat, and lymph nodes ... swallowing A change or hoarseness in the voice Head and neck cancers are twice as common in ...

  13. 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.

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

    OpenAIRE

    Liu, Pin

    2008-01-01

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

  15. Discontinuity effects in dynamically loaded tilting pad journal bearings

    DEFF Research Database (Denmark)

    Thomsen, Kim; Klit, Peder; Vølund, Anders

    2011-01-01

    This paper describes two discontinuity effects that can occur when modelling radial tilting pad bearings subjected to high dynamic loads. The first effect to be treated is a pressure build-up discontinuity effect. The second effect is a contact-related discontinuity that disappears when a contact...... force is included in the theoretical model. Methods for avoiding the pressure build-up discontinuity effect are proposed....

  16. Tilt stability of rotating current rings with passive conductors

    International Nuclear Information System (INIS)

    Zweibel, E.G.; Pomphrey, N.

    1984-12-01

    We study the combined effects of rotation and resistive passive conductors on the stability of a rigid current in an external magnetic field. We present numerical and approximate analytical solutions to the equations of motion, which show that the ring is always tilt unstable on the resistive decay timescale of the conductors, although rotation and eddy currents may stabilize it over short times. Possible applications of our model include spheromaks which rotate or which are encircled by energetic particle rings

  17. Association Between Optic Nerve Head Deformation and Retinal Microvasculature in High Myopia.

    Science.gov (United States)

    Sung, Mi Sun; Lee, Tae Hee; Heo, Hwan; Park, Sang Woo

    2018-04-01

    To evaluate the retinal microvasculature of peripapillary and macular regions in highly myopic eyes and investigate the association between the vascular parameters and optic nerve head (ONH) deformation. Cross-sectional study. Seventy-one subjects with highly myopic eyes and 26 subjects with emmetropic eyes were included. Horizontal B-scan images of the ONH were obtained using optical coherence tomography (OCT) and horizontal tilt angles were measured. Integrated automated algorithms in the Avanti OCT angiography were used to quantify the peripapillary vessel density and area of the foveal avascular zone (FAZ) at the level of superficial and deep vascular networks. Association between horizontal disc tilt and the vascular parameters was evaluated. The mean axial length and horizontal tilt angle were 26.73 ± 0.63 mm and 9.77 ± 3.00 degrees in the highly myopic group and 23.46 ± 0.55 mm and 5.95 ± 3.48 degrees in the emmetropic group, respectively. Highly myopic eyes exhibited significantly lower average peripapillary vessel density (P = .010) and larger superficial and deep FAZs (P = .001 and P < .001, respectively) compared with emmetropic eyes. Linear regression analyses showed that horizontal tilt angle significantly correlated the average peripapillary vessel density (P = .037) and the areas of superficial (P < .001) and deep (P < .001) FAZs. The retinal microvasculature was significantly different in highly myopic eyes according to the degree of horizontal optic disc tilt. In addition to peripapillary vessel density, FAZ can be affected by the degree of optic disc tilt. Copyright © 2018 Elsevier Inc. All rights reserved.

  18. Direct cone beam SPECT reconstruction with camera tilt

    International Nuclear Information System (INIS)

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

    1993-01-01

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

  19. Modeling of Tilting-Pad Journal Bearings with Transfer Functions

    Directory of Open Access Journals (Sweden)

    J. A. Vázquez

    2001-01-01

    Full Text Available Tilting-pad journal bearings are widely used to promote stability in modern rotating machinery. However, the dynamics associated with pad motion alters this stabilizing capacity depending on the operating speed of the machine and the bearing geometric parameters, particularly the bearing preload. In modeling the dynamics of the entire rotor-bearing system, the rotor is augmented with a model of the bearings. This model may explicitly include the pad degrees of freedom or may implicitly include them by using dynamic matrix reduction methods. The dynamic reduction models may be represented as a set of polynomials in the eigenvalues of the system used to determine stability. All tilting-pad bearings can then be represented by a fixed size matrix with polynomial elements interacting with the rotor. This paper presents a procedure to calculate the coefficients of polynomials for implicit bearing models. The order of the polynomials changes to reflect the number of pads in the bearings. This results in a very compact and computationally efficient method for fully including the dynamics of tilting-pad bearings or other multiple degrees of freedom components that interact with rotors. The fixed size of the dynamic reduction matrices permits the method to be easily incorporated into rotor dynamic stability codes. A recursive algorithm is developed and presented for calculating the coefficients of the polynomials. The method is applied to stability calculations for a model of a typical industrial compressor.

  20. Low-Frequency Otolith Function in Microgravity: A Re-Evaluation of the Otolith Tilt-Translation Reinterpretation (OTTR) Hypothesis

    Science.gov (United States)

    Moore, Steven T.; Cohen, Bernard; Clement, Gilles; Raphan, Theodore

    1999-01-01

    On Earth, the low-frequency afferent signal from the otoliths encodes head tilt with respect to the gravitational vertical, and the higher frequency components reflect both tilt and linear acceleration of the head. In microgravity, static tilt of the head does not influence otolith output, and the relationship between sensory input from the vestibular organs, and the visual, proprioceptive and somatosensory systems, would be disrupted. Several researchers have proposed that in 0-g this conflict may induce a reinterpretation of all otolith signals by the brain to encode only linear translation (otolith tilt-translation reinterpretation or OTTR). Ocular counter-rolling (OCR) is a low-frequency otolith-mediated reflex, which generates compensatory torsional eye movements (rotation about the visual axis) towards the spatial vertical during static roll tilt with a gain of approximately 10%. Transient linear acceleration and off-axis centrifugation at a constant angular velocity can also generate OCR. According to the OTTR hypothesis, OCR should be reduced in microgravity, and immediately upon return from a 0-g environment. Results to date have been inconclusive. OCR was reduced following the 10 day Spacelab-1 mission in response to leftward roll tilts (28-56% in 3 subjects and unchanged in one subject), and sinusoidal linear oscillations at 0.4 and 0.8 Hz. OCR gain declined 70% in four monkeys following a 14 day COSMOS mission. Following a 30 day MIR mission OCR gain decreased in one astronaut, but increased in two others following a 180 day mission. We have studied the affect of microgravity on low-frequency otolith function as part of a larger study of the interaction of vision and the vestibular system. This experiment (E-047) involved off-axis centrifugation of payload crewmembers and flew aboard the recent Neurolab mission (STS 90). Presented below are preliminary results focusing on perception and the OCR response during both centrifugation and static tilt.

  1. 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...... friction and a small pressure build-up. As in parallel-step bearings the recesses may also have a depth of the same order of magnitude as the oil film thickness. Such recesses are characterized by a strong pressure build-up caused by the reduction of the flow area at the end of the recess. Numerical models...... 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...

  2. 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

    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...... with pacemakers has a high diagnostic yield. Although, the majority of patients had a vasodepressor or orthostatic hypotensive response, cardioinhibitory response leading to syncope was also seen....

  3. Tonic ocular tilt reaction simulating a superior oblique palsy: diagnostic confusion with the 3-step test.

    Science.gov (United States)

    Donahue, S P; Lavin, P J; Hamed, L M

    1999-03-01

    The tonic ocular tilt reaction (OTR) consists of vertical divergence of the eyes (skew deviation), bilateral conjugate ocular torsion, and paradoxical head tilt. The head and superior pole of both eyes are rotated toward the hypotropic eye. To describe ocular motility and torsion findings in 5 patients with OTRs that mimicked superior oblique palsies (SOPs). In 5 patients, results of the 3-step test suggested an SOP (bilateral in 1 patient); however, no patient had the expected excyclotorsion of the hypertropic eye. Two patients had conjugate ocular torsion (intorsion of the hypertropic eye and extorsion of the hypotropic eye), and 2 patients had only intorsion of the hypertropic eye. All had other neurologic features consistent with more widespread brainstem disease. Vertical ocular deviations that 3-step to an SOP are not always caused by fourth nerve weakness. When a patient with an apparent fourth nerve palsy has ocular torsion that is inconsistent with an SOP, OTR should be suspected, especially if vestibular system or posterior fossa dysfunction coexists. The rules for the 3-step test for an SOP may be fulfilled by damaging the otolithic projections corresponding to projections of the contralateral anterior semicircular canal. Because results of the Bielschowsky head tilt test may be positive in patients with the OTR, the feature distinguishing OTR from an SOP is the direction of torsion. We advocate use of a fourth step-evaluation of ocular torsion-in addition to the standard 3 steps.

  4. 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.

  5. Head Lice

    Science.gov (United States)

    Head lice are parasitic wingless insects. They live on people's heads and feed on their blood. An adult louse ... Children ages 3-11 and their families get head lice most often. Personal hygiene has nothing to ...

  6. 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.

  7. Spatial coherence profilometry on tilted surfaces

    Czech Academy of Sciences Publication Activity Database

    Pavlíček, Pavel; Halouzka, M.; Duan, Z.; Takeda, M.

    2009-01-01

    Roč. 48, č. 34 (2009), H40-H47 ISSN 0003-6935 R&D Projects: GA MŠk(CZ) 1M06002 Institutional research plan: CEZ:AV0Z10100522 Keywords : tilted surface * spatial coherence profilometry * spatial coherence * measurement error * shape measurement Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.410, year: 2009

  8. "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…

  9. Understanding the Hydromechanical Behavior of a Fault Zone From Transient Surface Tilt and Fluid Pressure Observations at Hourly Time Scales

    Science.gov (United States)

    Schuite, Jonathan; Longuevergne, Laurent; Bour, Olivier; Burbey, Thomas J.; Boudin, Frédérick; Lavenant, Nicolas; Davy, Philippe

    2017-12-01

    Flow through reservoirs such as fractured media is powered by head gradients which also generate measurable poroelastic deformation of the rock body. The combined analysis of surface deformation and subsurface pressure provides valuable insights of a reservoir's structure and hydromechanical properties, which are of interest for deep-seated CO2 or nuclear waste storage for instance. Among all surveying tools, surface tiltmeters offer the possibility to grasp hydraulically induced deformations over a broad range of time scales with a remarkable precision. Here we investigate the information content of transient surface tilt generated by the pressurization a kilometer scale subvertical fault zone. Our approach involves the combination of field data and results of a fully coupled poromechanical model. The signature of pressure changes in the fault zone due to pumping cycles is clearly recognizable in field tilt data and we aim to explain the peculiar features that appear in (1) tilt time series alone from a set of four instruments and 2) the ratio of tilt over pressure. We evidence that the shape of tilt measurements on both sides of a fault zone is sensitive to its diffusivity and its elastic modulus. The ratio of tilt over pressure predominantly encompasses information about the system's dynamic behavior and extent of the fault zone and allows separating contributions of flow in the different compartments. Hence, tiltmeters are well suited to characterize hydromechanical processes associated with fault zone hydrogeology at short time scales, where spaceborne surveying methods fail to recognize any deformation signal.

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

    International Nuclear Information System (INIS)

    Tannast, M.; Murphy, S.B.; Langlotz, F.; Anderson, S.E.; Siebenrock, K.A.

    2006-01-01

    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.)

  11. Performance Evaluation and Software Design for EVA Robotic Assistant Stereo Vision Heads

    Science.gov (United States)

    DiPaolo, Daniel

    2003-01-01

    The purpose of this project was to aid the EVA Robotic Assistant project by evaluating and designing the necessary interfaces for two stereo vision heads - the TracLabs Biclops pan-tilt-verge head, and the Helpmate Zebra pan-tilt-verge head. The first half of the project consisted of designing the necessary software interface so that the other modules of the EVA Robotic Assistant had proper access to all of the functionalities offered by each of the stereovision heads. This half took most of the project time, due to a lack of ready-made CORBA drivers for either of the heads. Once this was overcome, the evaluation stage of the project began. The second half of the project was to take these interfaces and to evaluate each of the stereo vision heads in terms of usefulness to the project. In the key project areas such as stability and reliability, the Zebra pan-tilt-verge head came out on top. However, the Biclops did have many more advantages over the Zebra, such as: lower power consumption, faster communications, and a simpler, cleaner API. Overall, the Biclops pan-tilt-verge head outperformed the Zebra pan-tilt-verge head.

  12. Notebook computer use with different monitor tilt angle: effects on posture, muscle activity and discomfort of neck pain users.

    Science.gov (United States)

    Chiou, Wen-Ko; Chou, Wei-Ying; Chen, Bi-Hui

    2012-01-01

    This study aimed to evaluate the posture, muscle activities, and self reported discomforts of neck pain notebook computer users on three monitor tilt conditions: 100°, 115°, and 130°. Six subjects were recruited in this study to completed typing tasks. Results showed subjects have a trend to show the forward head posture in the condition that monitor was set at 100°, and the significant less neck and shoulder discomfort were noted in the condition that monitor was set at 130°. These result suggested neck pain notebook user to set their monitor tilt angle at 130°.

  13. 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 ...

  14. Design and Development of Tilting Rotary Furnace

    Science.gov (United States)

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

    2018-02-01

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

  15. Reactor pressure vessel vented head

    Science.gov (United States)

    Sawabe, James K.

    1994-01-11

    A head for closing a nuclear reactor pressure vessel shell includes an arcuate dome having an integral head flange which includes a mating surface for sealingly mating with the shell upon assembly therewith. The head flange includes an internal passage extending therethrough with a first port being disposed on the head mating surface. A vent line includes a proximal end disposed in flow communication with the head internal passage, and a distal end disposed in flow communication with the inside of the dome for channeling a fluid therethrough. The vent line is fixedly joined to the dome and is carried therewith when the head is assembled to and disassembled from the shell.

  16. Using Concurrent Cardiovascular Information to Augment Survival Time Data for Evaluating Orthostatic Tilt Test Performance

    Science.gov (United States)

    Feiveson, Alan H.; Fiedler, James; Lee, Stuart M. C.; Koslovsky, Matthew D.; Stenger, Michael B.; Platts, Steven H.

    2018-01-01

    Head-up tilt (HUT) tests often are used in research to measure orthostatic intolerance (OI) (inability to appropriately control blood pressure while upright) in clinical populations and otherwise healthy individuals after interventions. Post-space flight orthostatic intolerance is a well-known phenomenon, and countermeasures to its development has been an active area of research at NASA. In the NASA HUT protocol, subjects lie horizontally on an automatic tilt table for baseline measurements before being raised to 80deg head-up tilt for a defined period of time or until signs or symptoms of presyncope ensues (light-headedness, nausea, dizziness, sweating, weakness or fainting). Multiple measures are collected to evaluate the cardiovascular system's ability to respond appropriately to the orthostatic challenge. However if the intended duration of the HUT is short, the ability to detect changes in OI due to an intervention or its prevention by a countermeasure may be limited by a small number of failures to permit comparisons based on survival time alone. Thus, the time-trajectory of the cardiovascular data becomes an important additional source of information. In particular, we will show how various measures of trajectory variability can effectively augment survival analysis for the assessment of OI in a joint model when high censoring rates are present.

  17. Determinants of Motion Sickness in Tilting Trains: Coriolis/Cross-Coupling Stimuli and Tilt Delay.

    Science.gov (United States)

    Bertolini, Giovanni; Durmaz, Meek Angela; Ferrari, Kim; Küffer, Alexander; Lambert, Charlotte; Straumann, Dominik

    2017-01-01

    Faster trains require tilting of the cars to counterbalance the centrifugal forces during curves. Motion sensitive passengers, however, complain of discomfort and overt motion sickness. A recent study comparing different control systems in a tilting train, suggested that the delay of car tilts relative to the curve of the track contributes to motion sickness. Other aspects of the motion stimuli, like the lateral accelerations and the car jitters, differed between the tested conditions and prevented a final conclusion on the role of tilt delay. Nineteen subjects were tested on a motorized 3D turntable that simulated the roll tilts during yaw rotations experienced on a tilting train, isolating them from other motion components. Each session was composed of two consecutive series of 12 ideal curves that were defined on the bases of recordings during an actual train ride. The simulated car tilts started either at the beginning of the curve acceleration phase (no-delay condition) or with 3 s of delay (delay condition). Motion sickness was self-assessed by each subject at the end of each series using an analog motion sickness scale. All subjects were tested in both conditions. Significant increases of motion sickness occurred after the first sequence of 12 curves in the delay condition, but not in the no-delay condition. This increase correlated with the sensitivity of motion sickness, which was self-assessed by each subject before the experiment. The second sequence of curve did not lead to a significant further increase of motion sickness in any condition. Our results demonstrate that, even if the speed and amplitude are as low as those experienced on tilting trains, a series of roll tilts with a delay relative to the horizontal rotations, isolated from other motion stimuli occurring during a travel, generate Coriolis/cross-coupling stimulations sufficient to rapidly induce motion sickness in sensitive individuals. The strength and the rapid onset of the motion

  18. Determinants of Motion Sickness in Tilting Trains: Coriolis/Cross-Coupling Stimuli and Tilt Delay

    Directory of Open Access Journals (Sweden)

    Giovanni Bertolini

    2017-05-01

    Full Text Available Faster trains require tilting of the cars to counterbalance the centrifugal forces during curves. Motion sensitive passengers, however, complain of discomfort and overt motion sickness. A recent study comparing different control systems in a tilting train, suggested that the delay of car tilts relative to the curve of the track contributes to motion sickness. Other aspects of the motion stimuli, like the lateral accelerations and the car jitters, differed between the tested conditions and prevented a final conclusion on the role of tilt delay. Nineteen subjects were tested on a motorized 3D turntable that simulated the roll tilts during yaw rotations experienced on a tilting train, isolating them from other motion components. Each session was composed of two consecutive series of 12 ideal curves that were defined on the bases of recordings during an actual train ride. The simulated car tilts started either at the beginning of the curve acceleration phase (no-delay condition or with 3 s of delay (delay condition. Motion sickness was self-assessed by each subject at the end of each series using an analog motion sickness scale. All subjects were tested in both conditions. Significant increases of motion sickness occurred after the first sequence of 12 curves in the delay condition, but not in the no-delay condition. This increase correlated with the sensitivity of motion sickness, which was self-assessed by each subject before the experiment. The second sequence of curve did not lead to a significant further increase of motion sickness in any condition. Our results demonstrate that, even if the speed and amplitude are as low as those experienced on tilting trains, a series of roll tilts with a delay relative to the horizontal rotations, isolated from other motion stimuli occurring during a travel, generate Coriolis/cross-coupling stimulations sufficient to rapidly induce motion sickness in sensitive individuals. The strength and the rapid onset

  19. Head Injuries in Children

    Science.gov (United States)

    Pennington, Nicole

    2010-01-01

    School nurses play a crucial role in injury prevention and initial treatment when injuries occur at school. The role of school nurses includes being knowledgeable about the management of head injuries, including assessment and initial treatment. The school nurse must be familiar with the outcomes of a head injury and know when further evaluation…

  20. Listening talkers produce great spectral tilt contrasts

    DEFF Research Database (Denmark)

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

    It is well known that the envelope of the long-term average speech spectrum flattens with vocal effort. A recent study [1] showed that content words had a flatter spectral envelope than content words at the same overall level for a specific Danish speech material. The present paper investigates...... 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...... and function words and grouped by talker. The spectral tilt difference was then calculated as the average band-level difference for function words minus the average band-level difference for content words. This calculation was grouped per talker. For the monologues these differences ranged between 5 and 8 d...

  1. 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.

  2. 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.

  3. Temperature characteristics of tilted wave lasers

    Science.gov (United States)

    Maximov, Mikhail V.; Gordeev, Nikita Yu.; Shernyakov, Yuri M.; Payusov, Alexey S.; Kalyuzhnyy, Nikolay A.; Mintairov, Sergey A.; Kulagina, Marina M.; Zhukov, Alexey E.; Shchukin, Vitaly A.; Ledentsov, Nikolai N.

    2016-11-01

    We report on the temperature characteristics of edge-emitting tilted wave lasers (TWL) composed of a thin active waveguide (0.7 μm) optically coupled to a thick passive waveguide (26 μm). The active region is based on four 1040-nm InGaAs/GaAs quantum wells. The 2-mm-long and 50-μm-wide broad area lasers show characteristic temperature of 115 K and lasing up to 120°C in the continuous-wave mode. The maximal pulsed output power as high as 40 W was achieved being limited by the available current source. Vertical far-fields of the TWLs consist of two tilted narrow lobs (2.4 deg full width at half maximum each), which contain >70% of the total output power. The tilt angle of the lobes slightly increases with the temperature (by 1 deg/40°C) due to the transverse mode hopping caused by the temperature-induced changes of the waveguide refractive indices.

  4. A COMMON SOURCE OF ACCRETION DISK TILT

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  5. Head and Neck

    DEFF Research Database (Denmark)

    Højgaard, Liselotte; Berthelsen, Anne Kiil; Loft, Annika

    2014-01-01

    Positron emission tomography (PET)/computed tomography with FDG of the head and neck region is mainly used for the diagnosis of head and neck cancer, for staging, treatment evaluation, relapse, and planning of surgery and radio therapy. This article is a practical guide of imaging techniques......, including a detailed protocol for FDG PET in head and neck imaging, physiologic findings, and pitfalls in selected case stories....

  6. 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.

  7. Heads Up

    Science.gov (United States)

    ... Form Controls Cancel Submit Search the CDC HEADS UP Note: Javascript is disabled or is not supported ... please visit this page: About CDC.gov . HEADS UP Brain Injury Basics What Is a Concussion? Concussion ...

  8. Bottom head assembly

    International Nuclear Information System (INIS)

    Fife, A.B.

    1998-01-01

    A bottom head dome assembly is described which includes, in one embodiment, a bottom head dome and a liner configured to be positioned proximate the bottom head dome. The bottom head dome has a plurality of openings extending there through. The liner also has a plurality of openings extending there through, and each liner opening aligns with a respective bottom head dome opening. A seal is formed, such as by welding, between the liner and the bottom head dome to resist entry of water between the liner and the bottom head dome at the edge of the liner. In the one embodiment, a plurality of stub tubes are secured to the liner. Each stub tube has a bore extending there through, and each stub tube bore is coaxially aligned with a respective liner opening. A seat portion is formed by each liner opening for receiving a portion of the respective stub tube. The assembly also includes a plurality of support shims positioned between the bottom head dome and the liner for supporting the liner. In one embodiment, each support shim includes a support stub having a bore there through, and each support stub bore aligns with a respective bottom head dome opening. 2 figs

  9. The effect of seated pelvic tilt on posterior edge-loading in total hip arthroplasty: A finite element investigation.

    Science.gov (United States)

    Pierrepont, Jim; Yang, Long; Arulampalam, Jevan; Stambouzou, Catherine; Miles, Brad; Li, Qing

    2018-03-01

    Edge-loading of a ceramic-on-ceramic total hip replacement can lead to reproducible squeaking and revision. A patient's functional acetabular cup orientation, driven by their pelvic tilt, has been shown to be a significant factor in squeaking during hip flexion. The aim of this study was to investigate the effect of seated pelvic tilt on the contact mechanics at the ceramic bearing surface. A finite element model of a ceramic-on-ceramic total hip replacement was created. The cup was orientated at 40° inclination and 15° anteversion relative to the anterior pelvic plane. The stem was flexed 90° to replicate sitting in a chair. The model was loaded using data from in vivo measurements taken during a sit-to-stand activity. The pelvis was modelled in seven different sagittal positions, ranging from -30° to 30° of pelvic tilt, where a positive value denotes anterior pelvic tilt. Three different head sizes were investigated: 32, 36 and 40 mm. The maximum contact pressure and contact patch to rim distance were determined for each of the 21 simulations. Edge-loading (contact patch to rim distance Edge-loading initiated at seated pelvic tilts of 7°, 9° and 5° for the 32, 36 and 40 mm heads, respectively. Patients with anterior pelvic tilts in the seated position are susceptible to posterior edge-loading. As the position of the pelvis when seated is patient specific, cup orientation should be adjusted on an individual basis to minimise edge-loading.

  10. A computer simulation study of tilted smectic mesophases

    International Nuclear Information System (INIS)

    Withers, I.M.

    2000-05-01

    Results are presented from a series of simulations undertaken to determine the effect of a novel form of molecular biaxiality upon the phase behaviour of the well established Gay-Berne (GB) liquid crystal model. Firstly, the simulation of a bulk system interacting via the Internally-Rotated Gay Berne (IRGB) potential, which offers a single-site representation of a molecule rigidly constrained into a zig-zag conformation, is presented. The results of simulations performed for systems of IRGB particles with an aspect ratio of 3:1 confirm that the introduction of biaxiality into the model results in the destabilisation of the orientationally ordered phases. For particles with a sufficiently pronounced zig-zag conformation, this results in the complete destabilisation of the smectic A phase and the smectic B phase being replaced by the tilted smectic J phase. Following these observations, the effect upon the phase behaviour of increasing molecular elongation is also considered, with an increase in the aspect ratio from 3:1 to 4:1 resulting in the nematic and smectic J phases being replaced by smectic A and smectic G phases respectively. Secondly, a version of the IRGB potential modified to include a degree of molecular flexibility is considered. Results obtained from bulk systems interacting via the flexible IRGB for 3:1 and 4:1 molecules show that the introduction of flexibility results in the destabilisation of the smectic A phase and the stabilisation of the nematic and tilted hexatic phases. Finally, the effect upon the phase behaviour of the rigid IRGB model of the inclusion of a longitudinal linear quadrupole is examined. These results show that increasing quadrupole moment results in the destabilisation of the tilted hexatic phase, although the biaxial order parameter is increased with increasing quadrupole moment. There is no clear correlation between quadrupole magnitude and the other observed phase transitions, with the nematic and smectic A phases being

  11. The Significance of Immunohistochemical Staining, Including that for Glucose Transporter Protein Isoform 1, as Related to the Clinical and Angiographic Features of Adult Soft-Tissue Hemangioma and Arteriovenous Malformation in the Head and Neck

    International Nuclear Information System (INIS)

    Lee, Ha Young; Kim, Seon Mi; Choi, Jin Woo

    2009-01-01

    Glucose transporter protein isoform 1 (GLUT1) has been introduced to diagnose the hemangiomas of infancy. We investigated the usefulness of several immunohistochemical markers, including GLUT1, as related with the clinical and radiologic findings for making the diagnosis of adult subcutaneous vascular lesions in the head and neck. Materials and Methods: The 24 patients who underwent operations for soft tissue vascular lesion during the previous 7 years were included in this study. We analyzed the angiographic data, the clinical data and the immunohistochemical study results, including the GLUT1, S-100 protein and Movat pentichrome staining. Results: Twenty-two patients were confirmed to have arteriovenous malformation (AVM) and two hemangiomas, respectively. The number of lesions with positive Movat pentichrome, S-100 and GLUT1 staining in the patients with AVM and those patients with hemangioma were 22/22, 20/22 and 0/22, and 0/2, 0/2 and 0/2, respectively. For the 22 patients with AVMs, eight had a soft tissue vascular lesion at birth, 13 had cutaneous change and 15 had a change of the size of the lesion. For the 2 patients with one hemangioma each, neither patient had a soft tissue vascular lesion at birth, and both patients had cutaneous change and a change of the size of the lesion. The angiograms revealed a focal hypervascular mass (19/24) or diffuse staining (5/24) without showing significant features for making the definitive differential diagnosis. Our study revealed that none of the patients with AVM or hemangioma had GLUT1 positivity, and an arteriovenous malformation was more common than the adult-type hemangioma

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

    International Nuclear Information System (INIS)

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

    2006-01-01

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

  13. Head direction cell activity in mice: robust directional signal depends on intact otolith organs

    Science.gov (United States)

    Yoder, Ryan M.; Taube, Jeffrey S.

    2009-01-01

    The head direction (HD) cell signal is a representation of an animal's perceived directional heading with respect to its environment. This signal appears to originate in the vestibular system, which includes the semicircular canals and otolith organs. Preliminary studies indicate the semicircular canals provide a necessary component of the HD signal, but involvement of otolithic information in the HD signal has not been tested. The present study was designed to determine the otolithic contribution to the HD signal, as well as to compare HD cell activity of mice to that of rats. HD cell activity in the anterodorsal thalamus was assessed in wild-type C57BL/6J and otoconia-deficient tilted mice during locomotion within a cylinder containing a prominent visual landmark. HD cell firing properties in C57BL/6J mice were generally similar to those in rats. However, in C57BL/6J mice, landmark rotation failed to demonstrate dominant control of the HD signal in 36% of the sessions. In darkness, directional firing became unstable during 42% of the sessions, but landmark control was not associated with HD signal stability in darkness. HD cells were identified in tilted mice, but directional firing properties were not as robust as those of C57BL/6J mice. Most HD cells in tilted mice were controlled by landmark rotation, but showed substantial signal degradation across trials. These results support current models that suggest otolithic information is involved in the perception of directional heading. Furthermore, compared to rats, the HD signal in mice appears to be less reliably anchored to prominent environmental cues. PMID:19176815

  14. 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.

  15. Artificial gravity: head movements during short-radius centrifugation

    Science.gov (United States)

    Young, L. R.; Hecht, H.; Lyne, L. E.; Sienko, K. H.; Cheung, C. C.; Kavelaars, J.

    2001-01-01

    Short-radius centrifugation is a potential countermeasure to long-term weightlessness. Unfortunately, head movements in a rotating environment induce serious discomfort, non-compensatory vestibulo-ocular reflexes, and subjective illusions of body tilt. In two experiments we investigated the effects of pitch and yaw head movements in participants placed supine on a rotating bed with their head at the center of rotation, feet at the rim. The vast majority of participants experienced motion sickness, inappropriate vertical nystagmus and illusory tilt and roll as predicted by a semicircular canal model. However, a small but significant number of the 28 participants experienced tilt in the predicted plane but in the opposite direction. Heart rate was elevated following one-second duration head turns. Significant adaptation occurred following a series of head turns in the light. Vertical nystagmus, motion sickness and illusory tilt all decreased with adaptation. Consequences for artificial gravity produced by short-radius centrifuges as a countermeasure are discussed. Grant numbers: NCC 9-58. c 2001. Elsevier Science Ltd. All rights reserved.

  16. Thermal annealing of tilted fiber Bragg gratings

    Science.gov (United States)

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

    2016-05-01

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

  17. 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.

  18. 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

  19. 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.

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

    DEFF Research Database (Denmark)

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

    by calculating the mean flow index (Mx) between CBFV and MAP (Mxa) or CPP (Mxc). Spectral analysis of the HR variability was used to investigate baroreflex activity. Results: In the supine position, MAP and HR were higher in the patients compared to the controls (p = 0.0004 and p ... in patients compared to healthy control, indicating baroreflex dysfunction in patients. Conclusions: Patients with severe ABI and orthostatic instability during head-up tilt show unco-ordinated loss of autoregulation of cerebral blood flow more than 1 month after the accident. Interventions addressing...

  1. 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.

  2. Rotating Shaft Tilt Angle Measurement Using an Inclinometer

    OpenAIRE

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

    2015-01-01

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

  3. 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 ...

  4. 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.

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. New insight on the dynamic of the Fontaine de Vaucluse karst hydrosystem from tilt measurements

    Science.gov (United States)

    Lesparre, Nolwenn; Boudin, Frédéric; Chéry, Jean; Champollion, Cédric; Danquigny, Charles; Seat, Han Cheng; Cattoen, Michel; Longuevergne, Laurent

    2016-04-01

    The deformation of natural systems in response to subsurface water storage and redistribution provides insights into the main water flow path within heterogeneous systems, including the role of faults or fractures. A long baseline tiltmeter was installed in the low-noise underground laboratory of Rustrel (LSBB) to study the response of the Fontaine de Vaucluse (FDV) karst hydrosystem to water cycle. Tilt data and piezometric levels recorded in a borehole close to the LSBB show a strong correlation with the discharge of the system observed at the FDV spring 30 km away. Over several months, tilt data were recorded on three base lines, thus allowing, for the first time, to study the tilt gradient variation that appears homogeneous. Such information provides a significant constraint on hydrological processes leading to the measured deformation. Several deformation models were tested using the ADELI code to estimate the type of hydro-mechanical structure that could reproduce the measured tilt and its gradient. On one hand, models show that uniform loading at the surface produces a much smaller signal than observed on measured data. On the other hand, the deformation related to the filling of a fracture following a precipitation event requires unrealistic fracture size. Finally, we found that a suitable hydro-mechanical model corresponds to the loading of numerous fractures at the interface between the saturated and unsaturated zones. Such a configuration predicts a tilt distribution in agreement with observations. This study suggests that tilt networks into a karst system should provide key observation for deciphering hydrological processes.

  10. 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

  11. Artificial gravity: head movements during short-radius centrifugation

    NARCIS (Netherlands)

    Young, L. R.; Hecht, H.; Lyne, L. E.; Sienko, K. H.; Cheung, C. C.; Kavelaars, J.

    2001-01-01

    Short-radius centrifugation is a potential countermeasure to long-term weightlessness. Unfortunately, head movements in a rotating environment induce serious discomfort, non-compensatory vestibulo-ocular reflexes, and subjective illusions of body tilt. In two experiments we investigated the effects

  12. Lens decenter and tilt measurement by interferogram

    Science.gov (United States)

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

    2009-11-01

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

  13. Three-dimensional head and trunk movement characteristics during gait in children with spastic diplegia.

    Science.gov (United States)

    Heyrman, L; Feys, H; Molenaers, G; Jaspers, E; Monari, D; Meyns, P; Desloovere, K

    2013-09-01

    This study uses a recently developed trunk model to determine which head and trunk kinematic parameters differentiate children with spastic diplegia from typically developing (TD) children while walking. Differences in head and trunk parameters in relation to the severity of the motor involvement (GMFCS levels) were additionally examined. The trunk model consisted of five segments (pelvis, thorax, head, shoulder line, spine). Discrete kinematic parameters (ROM, mean position) and angular waveforms were compared between 20 children with spastic diplegia (age 9.8 years±2.9 years; GMFCS I: n=10, GMFCS II: n=10) and 20 individually age-matched TD children (9.7 years±3 years). A new measure for overall trunk pathology, the trunk profile score (TPS), was proposed and included in the comparative analysis. Compared to TD children, children with GMFCS II showed a significantly higher TPS and increased ROM for pelvis tilt, for thorax and head in nearly all planes, and the angle of kyphosis. In children with GMFCS I, only ROM of thorax lateral bending was significantly increased. Sagittal ROM differentiated best between GMFCS levels, with higher ROM found in children with GMFCS II. Current results provide new insights into head and trunk kinematics during gait in children with spastic diplegia. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Is the sacro-femoral-pubic angle predictive for pelvic tilt in adolescent idiopathic scoliosis patients?

    Science.gov (United States)

    Bao, Hongda; Liu, Zhen; Zhu, Feng; Zhu, Zezhang; Wang, Fei; Bentley, Mark; Qian, Bangping; Qiu, Yong

    2014-07-01

    This was a retrospective radiographic study. The aim of this study was to evaluate the correlation between pelvic tilt (PT) and the sacro-femoral-pubic angle (SFP angle) in AIS patients and to clarify whether the predictability of PT is affected by different curve patterns. Pelvic retroversion is one of the compensatory mechanisms to maintain upright position and is also tied to health-related quality of life in patients with adolescent idiopathic scoliosis (AIS). However, measurement of spino-pelvic parameters including PT may not be accurate because of difficulty in visualizing femoral heads on lateral radiographs in some patients. In this study, 101 female AIS patients were recruited. The subjects were divided into 2 groups: thoracic scoliosis (TS) and lumbar scoliosis (LS) group. Long-cassette standing upright radiographs were obtained; PT and SFP angles were measured through digital analysis software (Surgimap Spine Software, New York, NY). The relations between PT and SFP angle were determined by the Pearson correlation coefficient (r). Linear regressions between PT and SFP angle were also performed. The SFP angle was strongly correlated with PT in both groups, and PT could be estimated by the formulas: PT=74.052-0.991×SFP angle in the TS group and PT=65.345-0.881×SFP angle in the LS group. In the TS group, the SFP angle correlated with PT strongly with a Pearson coefficient of 0.65. Whereas in the LS group, the coefficient was weaker than that in the TS group (0.48 vs. 0.65); however, it still showed that PT was significantly associated with SFP. Given the high correlation between PT and SFP angle, the SFP angle should be considered a reliable alternative option to PT, which has routinely excellent visibility in coronal films in AIS patients. The predictability was more accurate for AIS patients with thoracic curves than with lumbar curves.

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

    NARCIS (Netherlands)

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

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

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

    Indian Academy of Sciences (India)

    S K Pal

    2017-06-12

    Jun 12, 2017 ... The present study deals with the characterization of subsurface coal fires of East Basuria colliery in. Jharia coal field, India using tilt derivative and downward continuation of magnetic data. Magnetic data processing methods such as diurnal correction, noise removal, reduction to pole, tilt derivative and.

  17. Ion kinetic effects on the tilt mode in FRCs

    International Nuclear Information System (INIS)

    Schwarzmeier, J.L.; Seyler, C.E.; Barnes, D.C.

    1981-01-01

    Theory and simulations have shown that field reversed configurations (FRG's) should be unstable magnetohydrodynamically to the tilting mode, yet tilting seldom is seen in the experiments. Profile effects (within MHD) and ion finite larmor radius (FLR) effects have been prosed to explain the observed stability of FRC's. The present work seeks to test both of these effects

  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. Orientation and alignment in beam tilted-foil spectroscopy

    International Nuclear Information System (INIS)

    Berry, H.G.

    1976-01-01

    The production of atomic orientation and alignment, by anisotropic excitation is analyzed. The stokes parameters of the light emitted from tilted-foil excited ions provide measurements of orientation and alignment, and some examples are given. The variations of the stokes parameters with foil tilt angle, excited state, ion velocity and foil material are compared with existing theories

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

    Indian Academy of Sciences (India)

    2014-02-06

    Feb 6, 2014 ... coupling of the guided modes shifts to the long wavelength as the tilt angle is increased. [3]. The central wavelength and the reflectivity of a TFBG are dependent on the angle. Due to the presence of tilt angle, the transmission spectra of TFBGs exposed in air con- sisted of multiple resonance peaks occurred ...

  1. 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

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

    Directory of Open Access Journals (Sweden)

    Hiroyuki Tsuchie

    2014-01-01

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

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

    Science.gov (United States)

    Yamada, Shin; Tazawa, Hiroshi; Kijima, Hiroaki; Shimada, Yoichi

    2014-01-01

    Nontraumatic anterior subluxation and dislocation of the hip joint are extremely rare. A 58-year-old woman presented to our outpatient clinic with left hip pain with a duration of 15 years. There was no history of trauma or other diseases. Her hip pain usually occurred only on walking and not at rest. Physical examinations demonstrated no tenderness in the hip joint. The range of motion of both hip joints was almost normal. Laxity of other joints was not observed. The bone mineral density of the lumbar spine and proximal femur confirmed a diagnosis of osteoporosis. A plain radiograph showed osteoarthritic changes of the hip joints, severe posterior pelvic tilt, and superior displacement of both femoral heads, especially in a standing position. Three-dimensional computed tomography (3DCT) revealed anterior subluxation of both femoral heads. Seven years after the initial visit, both hip joints showed progression to severe osteoarthritis. Although the exact cause remains unclear, lumbar kyphosis, posterior pelvic tilt, and a decrease in acetabular coverage may have influenced the current case. We should be aware of these factors when we examine patients with hip osteoarthritis. PMID:24592346

  4. Tilt of the radius from forearm rotational axis reliably predicts rotational improvement after corrective osteotomy for malunited forearm fractures.

    Science.gov (United States)

    Tatebe, Masahiro; Shinohara, Takaaki; Okui, Nobuyuki; Yamamoto, Michiro; Kurimoto, Shigeru; Hirata, Hitoshi

    2012-02-01

    Forearm rotation occurs around an axis connecting the center of the radial head and the fovea of the distal ulna. The purpose of the present study was to demonstrate the usefulness of the difference between forearm and proximal radial axis in the treatment of malunited forearm fractures. We reviewed the results of eight corrective osteotomies for malunited fractures of the forearm without dislocations of the wrist or elbow. Subjects were 6 men and 2 women (mean age, 15 years; range, 10-21 years). Corrective osteotomy was performed at the fracture site. Preoperatively and at final follow-up, the are of forearm rotation was recorded and anteroposterior and lateral X-rays were taken. Proximal radius tilt was defined as the angle between the rotational axis of the forearm and the axis of the proximal radius. Corrective osteotomy improved proximal radius tilt in all cases. Three patients were considered to have malrotation. Postoperative rotational are correlated with proximal radial tilt (r = -0.83). No significant difference in rotational arc was evident between malunited cases and the remaining cases. To improve forearm rotation, corrective osteotomy should be planned to minimize proximal radius tilt.

  5. Head Injuries

    Science.gov (United States)

    ... numbness in the arms or legs. Loss of consciousness. Seizures. What causes a head injury? There are ... Aid and Injury Prevention Crisis Situations Pets and Animals myhealthfinder Food and Nutrition Healthy Food Choices Weight ...

  6. Head Lice

    Science.gov (United States)

    ... Head lice cannot jump or fly. Only the direct contact with an infested person or their contaminated ... the complex world of health care and making…Sports and Exercise at Every AgeRead Article >>Exercise and ...

  7. Influence of patient head positioning on measured axial tooth inclination in panoramic radiography.

    Science.gov (United States)

    Hardy, Timothy C; Suri, Lokesh; Stark, Paul

    2009-06-01

    Panoramic radiographs are routinely used to assess the mesiodistal axial inclination of teeth (MDAI) in orthodontic treatment. These radiographs are sensitive to minor deviations from standard head position that result in image distortions. The aim of this study is to measure and quantify the changes in MDAI on panoramic radiograph resulting from changes in patient head position. The testing devise was a human skull with guide wires placed on the facial surface of the teeth and alveolar process along the long axis of each tooth. Panoramic radiographs were captured digitally with the orientation of the skull in Frankfurt horizontal plane parallel to the floor and with 1 degrees , 2 degrees , 5 degrees , 7 degrees , and 10 degrees both superior and inferior rotations. The mesiodistal tooth angulations were determined using MIPAC software (DentalEye and LEAD Technologies, Inc. 2005). The more distal the position of the tooth in the arch the greater the change in MDAI with a change in vertical head position. A maximum change of approximately 10 degrees was observed in MDAI of both the maxillary and mandibular molars with a corresponding superior head tilt of 10 degrees. The Mandibular anteriors displayed significant inconsistencies in MDAI with both superior and inferior head tilt. A superior head tilt produced a greater change in mesiodistal angulation than did an inferior head tilt. Accurately taken panoramic radiographs can serve as a convenient tool for evaluating the MDAI before, during and after orthodontic treatment. Additional radiographs are recommended for the mandibular anteriors.

  8. Motion perception during tilt and translation after space flight

    Science.gov (United States)

    Clément, Gilles; Wood, Scott J.

    2013-11-01

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

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

    Science.gov (United States)

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

    2018-02-01

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

  10. 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.

  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...... distortion and vertical alignment, it was only possible to a limited extent to relate sonic anemometer flow tilt angles to upwind forest edges, but the results by the lidar indicated that an internal boundary layer affect flow tilt angles at 21m above the forest. This is in accordance with earlier studies...

  12. Clinical-dosimetric analysis of measures of dysphagia including gastrostomy-tube dependence among head and neck cancer patients treated definitively by intensity-modulated radiotherapy with concurrent chemotherapy

    Directory of Open Access Journals (Sweden)

    Newman Kathleen

    2009-11-01

    Full Text Available Abstract Purpose To investigate the association between dose to various anatomical structures and dysphagia among patients with head and neck cancer treated by definitive intensity-modulated radiotherapy (IMRT and concurrent chemotherapy. Methods and materials Thirty-nine patients with squamous cancer of the head and neck were treated by definitive concurrent chemotherapy and IMRT to a median dose of 70 Gy (range, 68 to 72. In each patient, a gastrostomy tube (GT was prophylacticly placed prior to starting treatment. Prolonged GT dependence was defined as exceeding the median GT duration of 192 days. Dysphagia was scored using standardized quality-of-life instruments. Dose-volume histogram (DVH data incorporating the superior/middle pharyngeal constrictors (SMPC, inferior pharyngeal constrictor (IPC, cricoid pharyngeal inlet (CPI, and cervical esophagus (CE were analyzed in relation to prolonged GT dependence, dysphagia, and weight loss. Results At 3 months and 6 months after treatment, 87% and 44% of patients, respectively, were GT dependent. Spearman's ρ analysis identified statistical correlations (p 30%, IPC V60 > 60%, IPC Dmean > 60 Gy, and CPI Dmax > 62 Gy predicted for greater than 50% probability of prolonged GT dependence. Conclusion Our analysis suggests that adhering to the following parameters may decrease the risk of prolonged GT dependence and dysphagia: IPC V65

  13. Tilt Rotor Aeroacoustic Model (TRAM): A New Rotorcraft Research Facility

    National Research Council Canada - National Science Library

    Young, Larry A

    1998-01-01

    ...". These two test stands are inclusively called the Tilt Rotor Aeroacoustic Model "TRAM". The baseline proprotors and airframe of the TRAM test stands are nominally 1/4-scale representations of the V-22 Osprey aircraft...

  14. 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.

  15. TRISH: the Toronto-IRIS Stereo Head

    Science.gov (United States)

    Jenkin, Michael R. M.; Milios, Evangelos E.; Tsotsos, John K.

    1992-03-01

    This paper introduces and motivates the design of a controllable stereo vision head. The Toronto IRIS stereo head (TRISH) is a binocular camera mount consisting of two AGC, fixed focal length color cameras forming a verging stereo pair. TRISH is capable of version (rotation of the eyes about the vertical axis so as to maintain a constant disparity), vergence (rotation of the eyes about the vertical axis so as to change the disparity), pan (rotation of the entire head about the vertical axis), and tilt (rotation of the eyes about the horizontal axis). One novel characteristic of the design is that the two cameras can rotate about their own optical axes (torsion). Torsion movement makes it possible to minimize the vertical component of the two-dimensional search which is associated with stereo processing in verging stereo systems.

  16. Head lice

    OpenAIRE

    Burgess, Ian F

    2011-01-01

    Head lice can only be diagnosed by finding live lice, as eggs take 7 days to hatch, and may appear viable for weeks after death of the egg. Infestation may be more likely in school children, with risks increased in children with more siblings, longer hair, or of lower socioeconomic group.

  17. 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

  18. Tilt Table Test: State of The Art

    Directory of Open Access Journals (Sweden)

    Gonzalo Barón-Esquivias

    2003-10-01

    Full Text Available The loss of consciousness has been a subject of wonder and uncertainty in humans, and for this reason it has been the object of medical investigation since the beginning of time. Even actually, it is certainly an unresolved clinical problem. Many centuries ago, complicated exorcisms and remedies were used on these unfortunate patients, who upon regaining consciousness would find themselves soaked in miraculous liquids, ingesting curative potions, and often on the way to be burned accused of being possessed. In the seventeen century, physicians began to relate loss of consciousness and haemodinamic changes. William Harvey was perhaps the first to describe a circulatory response (vasovagal reaction during a phlebotomy in the year 1628: “...Yet it fear or any other cause, or something do intervene through passion of the mind, so that the heart do beat more faintly, the blood will be no means pass through but drop after drop…”1. During the nineteenth century, loss of consciousness was the object of studies and research, and the vagally mediated cardioinhibition, as a primary cause, was noted by Foster who proposed that profound bradycardia diminished cerebral perfusion to a level inadequate to maintain consciousness2. At this time, it was reported the first use of the tilt-table test3. Commonly referred to as fainting or loss of consciousness, from last century the preferred medical term is syncope, which itself is derived from the Greek term “syncoptein” meaning “to cut short”. Syncope is defined as the sudden loss of consciousness and postural tone with spontaneous recovery. In 1907, Gowers was the first person to use the term vasovagal syncope4. In 1918 was published the work in which Cotton and Lewis described for the first time the clinical characteristics that are still used today to recognize the syncopal reaction5. However, it was not till 1932 when Lewis described this reaction as being characterized by a combination of bradycardia

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

    Science.gov (United States)

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

    2011-01-01

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

  20. Group theoretical analysis of octahedral tilting in perovskites

    International Nuclear Information System (INIS)

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

    1998-01-01

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

  1. Influence of body laterality on recovery from subjective visual vertical tilt after vestibular neuritis.

    Science.gov (United States)

    Toupet, Michel; Van Nechel, Christian; Bozorg Grayeli, Alexis

    2014-01-01

    The subjective visual vertical (SVV) is an indicator of vestibular otolithic function and mainly processed by the nondominant parietal cortex. We investigated the hypothesis that recovery from SVV tilt after vestibular neuritis can be influenced by the body's lateral preference. This prospective cohort follow-up study included 254 consecutive adult patients with vestibular neuritis. The recovery from SVV tilt was faster in patients with a left hand or eye dominance than in those with a right dominance. While in left-handers the side of the neuritis did not affect the speed of recovery, in right-handed subjects, the recovery from a right-sided neuritis was significantly slower than from a left-sided affection. These observations suggest that subjects with a left sensorimotor dominance have developed more significant midline-crossing projections to the parietal cortex, allowing them to cope faster with a unilateral vestibular deficit.

  2. Evidence of post-seismic creep type deformations derived by tilt and acoustic emission monitoring of mining induced seismic events

    Science.gov (United States)

    Milev, Alexander; Share, Pieter-Ewald; Naoi, Makoto; Durrheim, Raymond; Yabe, Yasuo; Ogasawara, Hiroshi; Nakatani, Masao

    2015-04-01

    In this study we try to understand pre- and post-failure rock behavior associated with mining induced seismic events. This involves underground installation of various high precision instruments, including geophones, acoustic emission sensors, tilt- and strain-meters at a number of sites in deep level South African gold mines. The rate of tilt, strain and the seismic ground motion were analysed in order to understand the coseismic and aseismic deformation of the rocks. A good correspondence between the coseismic and the aseismic deformations was found. The rate of coseismic and aseismic tilt, as well as seismicity recorded by the mine seismic network, are approximately constant until the daily blasting time, which takes place from about 19:30 until shortly before 21:00. During the blasting time and the subsequent seismic events, the coseismic tilt and strain shows a rapid increase. Much of the aseismic deformation, however, occurs independently of the seismic events and blasting. In an attempt to distinguish between the different mechanisms of tilting two types of events were recognized. The "fast" seismic events characterized with sharp increase of the tilt during the seismic rupture and "slow" seismic events characterized by creep type post seismic deformations. Tilt behaviour before and after a seismic event was also analysed. The fact that no recognizable aftertilt was observed for more of the "fast" seismic events means that there is no gradual release of stress and an associated continuous strain rate change afterwards. It can therefore be concluded that a large seismic event causes a rapid change in the state of stress rather than a gradual change in the strain rate During the monitoring period a seismic event with MW 2.2 occurred in the vicinity of the instrumented site. This event was recorded by both the CSIR integrated monitoring system and JAGUARS acoustic emission network. More than 21,000 AE aftershocks were located in the first 150 hours after the

  3. Analytical aeroelastic stability considerations and conversion loads for an XV-15 tilt-rotor in a wind tunnel simulation

    Science.gov (United States)

    Kottapalli, Sesi; Meza, Victor

    1992-01-01

    A rotorcraft analysis is conducted to assess tilt-rotor stability and conversion loads for the XV-15 rotor with metal blades within its specified test envelope. A 38-DOF flutter analysis based on the code by Johnson (1988) is developed to simulate a wind-tunnel test in which the rotor torque is constant and thereby study stability. The same analytical model provides the simulated loads including hub loads, blade loads, and oscillatory pitch-link loads with attention given to the nonuniform inflow through the proprotor in the presence of the wing. Tilt-rotor stability during the cruise mode is found to be sensitive to coupling effects in the control system stiffness, and a stability problem is identified in the XV-15 Advanced Technology Blades. The present analysis demonstrates that the tilt-rotor is stable within the specified test envelope of the NASA 40 x 80-ft wind tunnel.

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

    DEFF Research Database (Denmark)

    Riberholt, Christian; Olesen, Niels; Hovind, Peter

    2018-01-01

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

  5. [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.

  6. The relationship between anterior pelvic tilt and gait, balance in patient with chronic stroke.

    Science.gov (United States)

    Kim, Myoung-Kwon; Kim, Seong-Gil; Shin, Young-Jun; Choi, Eun-Hong; Choe, Yu-Won

    2018-01-01

    [Purpose] The aim of this study is to find out the association between anterior pelvic tilt and gait and balance in chronic stroke. [Subjects and Methods] Fourteen chronic stroke patients were included in this study. A palpation meter was employed to measure the anterior inclination of the pelvis. A GAITRite system automates measuring temporal and spatial gait parameters. A 10-Meter Walk test was used to measure gait speed. The Timed Up and Go test was used to measure the dynamic balance ability and gait ability of the participants. A BioRescue was used to assess balance by measuring the moving distance and area of the center of pressure. [Results] There were significant negative correlations between pelvic anterior tilt and velocity, step length, and stride. There were significant positive correlations between velocity and cadence, step length, and stride length. There were significant negative correlations between velocity and cycle time, H-H base, TUG, and 10MWT. There was significant negative correlation between cadence and cycle time and H-H base. [Conclusion] This study showed a negative correlation between pelvic anterior tilt and gait function including gait speed and step length.

  7. When dynamic, the head and face alone can express pride.

    Science.gov (United States)

    Nelson, Nicole L; Russell, James A

    2011-08-01

    Prior research suggested that pride is recognized only when a head and facial expression (e.g., tilted head with a slight smile) is combined with a postural expression (e.g., expanded body and arm gestures). However, these studies used static photographs. In the present research, participants labeled the emotion conveyed by four dynamic cues to pride, presented as video clips: head and face alone, body posture alone, voice alone, and an expression in which head and face, body posture, and voice were presented simultaneously. Participants attributed pride to the head and face alone, even when postural or vocal information was absent. Pride can be conveyed without body posture or voice. 2011 APA, all rights reserved

  8. The Influence of Injection Pockets on the Performance of Tilting-Pad Thrust Bearings: Part I – Theory

    DEFF Research Database (Denmark)

    Heinrichson, Niels; Santos, Ilmar

    2006-01-01

    ) analysis of tilting-pad thrust bearings to include the effects of high pressure injection and recesses in the bearing pad. The model is applied to the analysis of an existing bearing of large dimensions and the influence of the pocket is analyzed. It is shown that a shallow pocket positively influences......This is Part I of a two-part series of papers describing the effects of high pressure injection pockets on the operating conditions of tilting-pad thrust bearings. A numerical model based on the Reynolds equation is developed extending the three dimensional thermo-elasto-hydrodynamic (TEHD...

  9. Rotating Shaft Tilt Angle Measurement Using an Inclinometer

    Science.gov (United States)

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

    2015-10-01

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

  10. Rotating Shaft Tilt Angle Measurement Using an Inclinometer

    Directory of Open Access Journals (Sweden)

    Luo Jun

    2015-10-01

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

  11. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... Professions Site Index A-Z Computed Tomography (CT) - Head Computed tomography (CT) of the head uses special ... the Head? What is CT Scanning of the Head? Computed tomography, more commonly known as a CT ...

  12. 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....

  13. Head trauma in China.

    Science.gov (United States)

    Jiang, Ji-Yao

    2013-11-01

    The Chinese Head Trauma Data Bank (CHTDB) has been established, which includes 7,145 hospitalised cases with acute head trauma patients in 47 hospitals. We explored factors that might affect the outcome of acute traumatic brain injury. There was no statistical difference in the mortality rate between male (7.5%) and female (7.2%) patients (P>0.05). The mortality rate in children (65 years) was 7.3%, 7.2% and 9.0%, respectively (P>0.05). The mortality rate of patients with mild (2.7%), moderate (5.0%) and severe (21.8%) head trauma was significantly different (P40 mm Hg was 6.3%, 21.4% and 93.1%, respectively (Phead trauma data bank in China, has one of the largest numbers of cases of any head trauma data bank in the world. Our major findings on mortality may be helpful to neurosurgeons for predicting the outcome of acute head trauma patients. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. Penetrating head trauma: 03 rare cases and literature review ...

    African Journals Online (AJOL)

    Penetrating head trauma (PHT) include all open head injuries with foreign object in the brain. Although less common than closed head trauma, penetrating head trauma carry a worse prognosis. We received three unusual cases of penetrating head injuries whose prognosis was different according to clinical presentation ...

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

    Science.gov (United States)

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

    2017-08-16

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

  16. Method to fabricate a tilted logpile photonic crystal

    Science.gov (United States)

    Williams, John D.; Sweatt, William C.

    2010-10-26

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

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

    DEFF Research Database (Denmark)

    Dellwik, Ebba; Mann, Jakob; Bingöl, Ferhat

    2010-01-01

    A novel way of estimating near-surface mean flow tilt angles from ground based Doppler lidar measurements is presented. The results are compared with traditional mast based in-situ sonic anemometry. The tilt angle assessed with the lidar is based on 10 or 30 min mean values of the velocity field......) 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...

  18. Ground tilt monitoring at Phlegraean Fields (Italy: a methodological approach

    Directory of Open Access Journals (Sweden)

    C. Del Gaudio

    2003-06-01

    Full Text Available Among geodetic methods used for monitoring ground deformation in volcanic areas, tiltmetry represents the most rapid technique and therefore it is used by almost all the volcanological observatories in the world. The deformation of volcanic building is not only the result of endogenous causes (i.e. dykes injection or magma rising, but also non-tectonic environmental factors. Such troubles cannot be removed completely but they can be reduce. This article outlines the main source of errors affecting the signals recorded by Phlegraean tilt, network, such as the dependence of the tilt response on temperature and to the thermoelastic effect on ground deformation. The analytical procedure used to evaluate about such errors and their reduction is explained. An application to data acquired from the tilt network during two distinct phases of ground uplift and subsidence of the Phlegraean Fields is reported.

  19. Absolute Measurement of Tilts via Fourier Analysis of Interferograms

    Science.gov (United States)

    Toland, Ronald W.

    2004-01-01

    The Fourier method of interferogram analysis requires the introduction of a constant tilt into the interferogram to serve as a carrier signal for information on the figure of the surface under test. This tilt is usually removed in the first steps of analysis and ignored thereafter. However, in the problem of aligning optical components and systems, knowledge of part orientation is crucial to proper instrument performance. This paper outlines an algorithm which uses the normally ignored carrier signal in Fourier analysis to compute an absolute tilt (orientation) of the test surface. We also provide a brief outline of how this technique, incorporated in a rotating Twyman-Green interferometer, can be used in alignment and metrology of optical systems.

  20. 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.

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

    Science.gov (United States)

    Johnston, M J; Mortensen, C E

    1974-12-13

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

  2. Reverse time migration in tilted transversely isotropic media

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Linbing; Rector III, James W.; Hoversten, G. Michael

    2004-07-01

    This paper presents a reverse time migration (RTM) method for the migration of shot records in tilted transversely isotropic (TTI) media. It is based on the tilted TI acoustic wave equation that was derived from the dispersion relation. The RTM is a full depth migration allowing for velocity to vary laterally as well as vertically and has no dip limitations. The wave equation is solved by a tenth-order finite difference scheme. Using 2D numerical models, we demonstrate that ignoring the tilt angle will introduce both lateral and vertical shifts in imaging. The shifts can be larger than 0.5 wavelength in the vertical direction and 1.5 wavelength in the lateral direction.

  3. Tilted dipole model for bias-dependent photoluminescence pattern

    Science.gov (United States)

    Fujieda, Ichiro; Suzuki, Daisuke; Masuda, Taishi

    2014-12-01

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

  4. Tilted dipole model for bias-dependent photoluminescence pattern

    International Nuclear Information System (INIS)

    Fujieda, Ichiro; Suzuki, Daisuke; Masuda, Taishi

    2014-01-01

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

  5. Abrupt Upper-Plate Tilting Upon Slab-Transition-Zone Collision

    Science.gov (United States)

    Crameri, F.; Lithgow-Bertelloni, C. R.

    2017-12-01

    During its sinking, the remnant of a surface plate crosses and interacts with multiple boundaries in Earth's interior. The most-prominent dynamic interaction arises at the upper-mantle transition zone where the sinking plate is strongly affected by the higher-viscosity lower mantle. Within our numerical model, we unravel, for the first time, that this very collision of the sinking slab with the transition zone induces a sudden, dramatic downward tilt of the upper plate towards the subduction trench. The slab-transition zone collision sets parts of the higher-viscosity lower mantle in motion. Naturally, this then induces an overall larger return flow cell that, at its onset, tilts the upper plate abruptly by around 0.05 degrees and over around 10 Millions of years. Such a significant and abrupt variation in surface topography should be clearly visible in temporal geologic records of large-scale surface elevation and might explain continental-wide tilting as observed in Australia since the Eocene or North America during the Phanerozoic. Unravelling this crucial mantle-lithosphere interaction was possible thanks to state-of-the-art numerical modelling (powered by StagYY; Tackley 2008, PEPI) and post-processing (powered by StagLab; www.fabiocrameri.ch/software). The new model that is introduced here to study the dynamically self-consistent temporal evolution of subduction features accurate subduction-zone topography, robust single-sided plate sinking, stronger plates close to laboratory values, an upper-mantle phase transition and, crucially, simple continents at a free surface. A novel, fully-automated post-processing includes physical model diagnostics like slab geometry, mantle flow pattern, upper-plate tilt angle and trench location.

  6. 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.

  7. Bray Head

    OpenAIRE

    Brocas, Samuel Frederick (Irish cityscape painter, watercolorist, and draftsman, 1792-1847)

    2008-01-01

    'A number of Martello towers were built around the coast of Ireland, especially along the east, from Millmount (Drogheda), to Bray, around Dublin Bay but also around Cork Harbour on the south coast. On the east coast, concentrated mainly around Dublin Bay, the towers were in line of sight of each other, providing the ability to communicate with one another, or warn of any incoming attacks.' (en.wikipedia.org/wiki/Martello_Tower#Ireland) 'Bray Head (Irish: Ceann Bre) is a hill and headland, of...

  8. Goniometer head

    International Nuclear Information System (INIS)

    Dzhazairov-Kakhramanov, V.; Berger, V.D.; Kadyrzhanov, K.K.; Zarifov, R.A.

    1994-01-01

    The goniometer head is an electromechanical instrument that performs the independent transfer of a testing sample on three coordinate axes (X, Y, Z) within limits of ±8 mm and independent rotation relative of these directions. The instrument comprises a sample holder, bellows component and three electrometer drives. The sample holder rotates around the axes X and Y, and is installed on the central arm which rotates around axis Z. One characteristic of this instrument is its independence which allows its use in any camera for researches in the field of radiation physics. 2 figs

  9. 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

    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...... and SmO2 (near-infrared spectroscopy), MCAvmean (transcranial Doppler) along with mean arterial pressure (MAP), heart rate (HR), stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR) (Modelflow®) were determined. Results (Pre)syncopal symptoms appeared in 17 subjects after 11 min...

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

    Science.gov (United States)

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

    Human spaceflight is associated with a loss of body protein most likely caused by muscle degradation. Additionally astronauts tend towards a high dietary intake of sodium chloride (NaCl), which has recently been shown to induce low grade metabolic acidosis (Frings-Meuthen et al. JBMR, Epub 2007). In several patterns, e.g. chronical renal failure, metabolic acidosis is associated with protein catabolism. We therefore hypothesized that high dietary intake of NaCl enforces protein losses in HDBR, a model for physiological changes in microgravity (µG). Eight healthy male subjects (mean age 26.25 ± 3.5; mean body weight: 78.5 ± 4.1 kg) participated in a 14-day bed rest study in the metabolic ward of the DLR - Institute of Aerospace Medicine, Cologne, Germany. The study was carried out in a cross over design, consisting of two phases, each lasting 22 days (5 days adaptation, 14 days 6° HDBR and 3 days recovery). Both study phases were identical with respect to environmental conditions and study protocol. Subjects received an individually tailored, weight-maintaining diet containing 1.3 g protein/kg/day. The diet was identical in both study phases with the exception of NaClintake: Every subject received a low NaCl diet (0.7 mmol/kg/day) in one phase and a high NaCl diet (7.7 mmol/kg/day) in another one. Blood gas for analysis of acid-base balance was implemented at days 4 and 5 of adaptation, days 2, 5, 7, 10, 12, 14 of HDBR and days 2, 3 of recovery. Continuous urine collection started on the first day in the metabolic ward to analyze nitrogen excretion. Nitrogen balance was calculated from the difference between protein intake and urinary nitrogen excretion, determined by use of chemiluminescence (Grimble et al. JPEN, 1988). Plasma pH did not change significantly (p=0.285), but plasma bicarbonate and base excess decreased (p=0.0175; p=0.0093) with high NaCl intake in HDBR compared to the low NaCl diet. Nitrogen balance in HDBR was negative, as expected in immobilization with low NaCl diet ( 0.34 ± 1.2 g/d). However, high NaCl intake in HDBR exacerbated the negative nitrogen balance to 1.34 ± 1.0 g/d (p¡0.001) compared to low NaCl. We conclude that high dietary NaCl intake induces low grade metabolic acidosis during HDBR. Low grade metabolic acidosis may be a reason for an increased protein turnover reflected by an exaggerated negative nitrogen balance in HDBR. Accordingly, a high dietary NaCl intake may exacerbate loss of body protein in µG via low grade metabolic acidosis.

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

    Science.gov (United States)

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

    1998-01-01

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

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

    Science.gov (United States)

    Elliott, Morgan B.; Martin, David S.; Westby, Christian M.; Stenger, Michael B.; Platts, Steven H.

    2014-01-01

    Carotid, brachial, and tibial arteries reacted differently to HDTBR. Previous studies have not analyzed the mechanical properties of the human brachial or anterior tibial arteries. After slight variations during bed-rest, arterial mechanical properties and IMT returned to pre-bed rest values, with the exception of tibial stiffness and PSE, which continued to be reduced post-bed rest while the DC remained elevated. The tibial artery remodeling was probably due to decreased pressure and volume. Resulting implications for longer duration spaceflight are unclear. Arterial health may be affected by microgravity, as shown by increased thoracic aorta stiffness in other ground based simulations (Aubert).

  13. Stability of multi orifice active tilting-pad journal bearings

    DEFF Research Database (Denmark)

    Haugaard, Asger M.; Santos, Ilmar

    2010-01-01

    The stability properties of actively lubricated tilting-pad journal bearings are investigated theoretically. The bearing preload factor and control system gains are varied, and stable and unstable regions are identified. It is seen, that the control system influences bearing stability, and that t......The stability properties of actively lubricated tilting-pad journal bearings are investigated theoretically. The bearing preload factor and control system gains are varied, and stable and unstable regions are identified. It is seen, that the control system influences bearing stability...

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

    Science.gov (United States)

    Bohannon, R W

    1993-10-01

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

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

    Science.gov (United States)

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

    2010-01-01

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

  16. The anterior tilt angle of the proximal tibia epiphyseal plate: A significant radiological finding in young children with trampoline fractures

    International Nuclear Information System (INIS)

    Stranzinger, Enno; Leidolt, Lars; Eich, Georg; Klimek, Peter Michael

    2014-01-01

    Objective: Evaluation of the anterior tilt angle of the proximal tibia epiphyseal plate in young children, which suffered a trampoline fracture in comparison with a normal population. Materials and methods: 62 children (31 females, 31 males) between 2 and 5 years of age (average 2 years 11 months, standard deviation 11 months) with radiographs in two views of the tibia were included in this retrospective study. 25 children with proximal tibia fractures were injured with a history of jumping on a trampoline. All other causes for tibia fractures were excluded. A normal age-mapped control cohort of 37 children was compared. These children had neither evidence of a trampoline related injury nor a fracture of the tibia. The anterior tilt angle of the epiphyseal plate of the tibia was defined as an angle between the proximal tibia physis and the distal tibia physis on a lateral view. Two radiologists evaluated all radiographs for fractures and measured the anterior tilt angle in consensus. An unpaired Student's t-test was used for statistical analysis (SPSS). Original reports were reviewed and compared with the radiological findings and follow-up radiographs. Results: In the normal control group, the average anterior tilt angle measured −3.2°, SD ± 2.8°. The children with trampoline fractures showed an anterior tilt of +4.4°, SD ± 2.9°. The difference was statistically significant, P < 0.0001. In 6 patients (24% of all patients with confirmed fractures) the original report missed to diagnose the proximal tibial fracture. Conclusion: Young children between 2 and 5 years of age are at risk for proximal tibia fractures while jumping on a trampoline. These fractures may be very subtle and difficult to detect on initial radiographs. Measurement of the anterior tilt angle of the proximal tibia epiphyseal plate on lateral radiographs is supportive for interpreting correctly trampoline fractures

  17. The anterior tilt angle of the proximal tibia epiphyseal plate: A significant radiological finding in young children with trampoline fractures

    Energy Technology Data Exchange (ETDEWEB)

    Stranzinger, Enno, E-mail: enno.stranzinger@insel.ch [University Hospital Bern, Inselspital, Department of Diagnostic, Interventional and Pediatric Radiology, CH-3010 Bern (Switzerland); Leidolt, Lars, E-mail: lars.leidolt@insel.ch [University Hospital Bern, Inselspital, Department of Diagnostic, Interventional and Pediatric Radiology, CH-3010 Bern (Switzerland); Eich, Georg, E-mail: georg.eich@ksa.ch [Cantonal Hospital Aarau, Pediatric Radiology, Tellstrasse, CH-5001 Aarau (Switzerland); Klimek, Peter Michael, E-mail: peter.klimek@ksa.ch [Cantonal Hospital Aarau, Pediatric Surgery, Tellstrasse, CH-5001 Aarau (Switzerland)

    2014-08-15

    Objective: Evaluation of the anterior tilt angle of the proximal tibia epiphyseal plate in young children, which suffered a trampoline fracture in comparison with a normal population. Materials and methods: 62 children (31 females, 31 males) between 2 and 5 years of age (average 2 years 11 months, standard deviation 11 months) with radiographs in two views of the tibia were included in this retrospective study. 25 children with proximal tibia fractures were injured with a history of jumping on a trampoline. All other causes for tibia fractures were excluded. A normal age-mapped control cohort of 37 children was compared. These children had neither evidence of a trampoline related injury nor a fracture of the tibia. The anterior tilt angle of the epiphyseal plate of the tibia was defined as an angle between the proximal tibia physis and the distal tibia physis on a lateral view. Two radiologists evaluated all radiographs for fractures and measured the anterior tilt angle in consensus. An unpaired Student's t-test was used for statistical analysis (SPSS). Original reports were reviewed and compared with the radiological findings and follow-up radiographs. Results: In the normal control group, the average anterior tilt angle measured −3.2°, SD ± 2.8°. The children with trampoline fractures showed an anterior tilt of +4.4°, SD ± 2.9°. The difference was statistically significant, P < 0.0001. In 6 patients (24% of all patients with confirmed fractures) the original report missed to diagnose the proximal tibial fracture. Conclusion: Young children between 2 and 5 years of age are at risk for proximal tibia fractures while jumping on a trampoline. These fractures may be very subtle and difficult to detect on initial radiographs. Measurement of the anterior tilt angle of the proximal tibia epiphyseal plate on lateral radiographs is supportive for interpreting correctly trampoline fractures.

  18. Evaluation of lesion distortion at various CT system tilts in the development of a hybrid system for dedicated mammotomography

    Science.gov (United States)

    Madhav, Priti; Crotty, Dominic J.; McKinley, Randolph L.; Tornai, Martin P.

    2007-03-01

    A hybrid SPECT-CT system for dedicated 3D breast imaging (mammotomography) is currently under development. Each imaging system will be placed on top of a single rotation stage and moved in unison azimuthally, with the SPECT system additionally capable of polar and radial motions. In this initial prototype, the CT system will initially be positioned at a fixed polar tilt. Using a phantom with three tungsten wires, the MTF of the CT system was measured in 3D for different CT system tilts. A phantom with uniformly arranged 0.5cm diameter acrylic spheres was suspended in air in the CT field of view, and also placed at multiple locations and orientations inside an oil-filled breast phantom to evaluate the effect of CT system tilt on lesion visibility and distortion. Projection images were collected using various simple circular orbits with fixed polar tilts ranging between +/-15°, and complex 3D saddle trajectories including combined polar and azimuthal motions at maximum polar tilt angles. Reconstructions were performed using an iterative reconstruction algorithm on 4x4 binned projection images with 0.508mm3 voxels. There was minor variation in the MTF in the imaged volume for the CT system at all trajectories, potentially due to the use of an iterative reconstruction algorithm. Results from the spherical cross phantoms indicated that there was more reconstruction inaccuracy and geometric distortion in the reconstructed slices with simple circular orbits with fixed tilt in contrast to complex 3D trajectories. Line profiles further showed a cupping artifact in planes farther away from the flat plane of the x-ray cone beam placed at different tilts. However, this cupping artifact was not seen for images acquired with complex 3D trajectories. This indicated that cupping artifacts can also be caused by undersampled cone beam data. These findings generally indicate that despite insufficient sampling with the cone beam imaging geometry, it is possible to place the CT system

  19. Ametropia, retinal anatomy, and OCT abnormality patterns in glaucoma. 2. Impacts of optic nerve head parameters

    Science.gov (United States)

    Baniasadi, Neda; Wang, Mengyu; Wang, Hui; Jin, Qingying; Elze, Tobias

    2017-12-01

    Clinicians use retinal nerve fiber layer thickness (RNFLT) measured by optical coherence tomography (OCT) as an adjunct to glaucoma diagnosis. Ametropia is accompanied by changes to the optic nerve head (ONH), which may affect how OCT machines mark RNFLT measurements as abnormal. These changes in abnormality patterns may bias glaucoma diagnosis. Here, we investigate the relationship between OCT abnormality patterns and the following ONH-related and ametropia-associated parameters on 421 eyes of glaucoma patients: optic disc tilt and torsion, central retinal vessel trunk location (CRVTL), and nasal and temporal retinal curvature adjacent to ONH, quantified as nasal/temporal slopes of the inner limiting membrane. We applied multivariate logistic regression with abnormality marks as regressands to 40,401 locations of the peripapillary region and generated spatial maps of locations of false positive/negative abnormality marks independent of glaucoma severity. Effects of torsion and temporal slope were negligible. The effect of tilt could be explained by covariation with ametropia. For CRVTL/nasal slope, abnormality pattern shifts at 7.2%/23.5% of the peripapillary region were detected, respectively, independent of glaucoma severity and ametropia. Therefore, CRVTL and nasal curvature should be included in OCT RNFLT norms. Our spatial location maps may aid clinicians to improve diagnostic accuracy.

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

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Earth System Science; Volume 126; Issue 4. Downward continuation and tilt derivative of magnetic data for delineation of concealed coal fire in East Basuria Colliery, Jharia coal field, India. S K Pal Jitendra Vaish Sahadev Kumar Piyush Priyam Abhay Kumar Bharti Rajwardhan Kumar. Volume ...

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

    Indian Academy of Sciences (India)

    S K Pal

    2017-06-12

    Jun 12, 2017 ... are corroborated with multi-seam occurrences, mine working levels and surface manifestation which are also correlated well with 3D model of downward continued anomaly distribution. Keywords. Downward continuation; tilt derivative; magnetic data; coal fire mapping; Jharia coal field;. India. 1.

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

    Indian Academy of Sciences (India)

    E-mail: oprakash@rrcat.gov.in. DOI: 10.1007/s12043-013-0672-7; ePublication: 6 February 2014. Abstract. This paper reports the study on development of tilted fibre Bragg gratings using highly coherent 255 nm radiation, obtained from the second harmonic generation (SHG) of copper vapour laser (CVL). The transmission ...

  3. Modelling and Simulations of a Narrow Track Tilting Vehicle

    Directory of Open Access Journals (Sweden)

    JJ Chong

    2016-10-01

    Full Text Available Narrow track tilting vehicle is a new category of vehicle that combines the dynamical abilities of a passenger car with a motorcycle. In the presence of overturning moments during cornering, an accurate assessment of the lateral dynamics plays an important role to improve their stability and handling. In order to stabilise or control the narrow tilting vehicle, the demand tilt angle can be calculated from the vehicle’s lateral acceleration and controlled by either steering input of the vehicle or using additional titling actuator to reach this desired angle. The aim of this article is to present a new approach for developing the lateral dynamics model of a narrow track tilting vehicle. First, this approach utilises the well-known geometry ‘bicycle model’ and parameter estimation methods. Second, by using a tuning method, the unknown and uncertainties are taken into account and regulated through an optimisation procedure to minimise the model biases in order to improve the modelling accuracy. Therefore, the optimised model can be used as a platform to develop the vehicle control strategy. Numerical simulations have been performed in a comparison with the experimental data to validate the model accuracy.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-04-15

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

  5. Tilt Train Technology : A State of the Art Survey

    Science.gov (United States)

    1992-05-01

    This report presents an overview of the state-of-the-art in tilt-train technology. It is intended to give the reader a better understanding of the unique features of this approach to train design and the variations that exist. Briefly described is th...

  6. Manipulation of enhanced absorption with tilted hexagonal boron nitride slabs

    Science.gov (United States)

    Wu, Xiaohu; Fu, Ceji

    2018-04-01

    The wavevector of electromagnetic wave propagation in a hexagonal boron nitride (hBN) slab can be controlled by tilting its optical axis. This property can be used to manipulate the absorption in a hBN slab. By carefully analyzing the dependence of the absorptivity of a thin hBN slab on the tilted angle of its optical axis, we propose a structure that can realize great absorptivity enhancement in a band by stacking hBN slabs of different tilted angles. Our numerical results show that the absorptivity of a structure made of 91 stacked hBN slabs can be achieved higher than 0.94 in the wavenumber range from 1367 to 1580 cm-1 when the tilted angles of the slabs are properly arranged. The strong absorption is attributed to the combination of impedance matching at the slab interfaces and enlarged wavevectors in the slabs. This work reveals a novel way to realize strong absorption with anisotropic materials for applications in areas such as thermal radiative energy harvesting and conversion.

  7. Dynamic tilt illusion induced by continuous contextual orientation alternations.

    Science.gov (United States)

    Yuan, Xiangyong; Zhang, Xilei; Jiang, Yi

    2017-11-01

    In the classic tilt illusion, the perceived orientation of a center patch is shifted away from its oriented context. Additionally, a stronger illusion effect is yielded when the center patch is simultaneously rather than asynchronously presented with a constant context for a shorter duration. However, little is known about the temporal characteristic of the tilt illusion in a reverse situation in which a constant center patch is presented throughout while the contexts change. Therefore, we continuously alternated two opposite-oriented contexts and manipulated alternate speeds to examine how the tilt illusion would build up as a function of dynamic contextual alternation. Our results revealed that dynamic alternations between leftward- and rightward-oriented contexts caused a static vertical grating at the center to apparently sway from side to side. More importantly, the apparent sway illusion was modulated by the alternate speed of the oriented contexts (up to 8-10 Hz); the quicker the alternation is, the faster and weaker the apparent sway is. Intriguingly, the temporal characteristic of the "dynamic tilt illusion" suggests that, under a varying environment, the suppressions from temporally adjacent surrounds would be chunked into discrete epochs before affecting our percept.

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

    Science.gov (United States)

    Chen, Zhen; Dorfman, Kevin D.

    2013-01-01

    Using Brownian dynamics simulations, we show that DNA electrophoresis in a hexagonal array of micron-sized posts changes qualitatively when the applied electric field vector is not coincident with the lattice vectors of the array. DNA electrophoresis in such “tilted” post arrays is superior to the standard “un-tilted” approach; while the time required to achieve a resolution of unity in a tilted post array is similar to an un-tilted array at a low electric field strengths, this time (i) decreases exponentially with electric field strength in a tilted array and (ii) increases exponentially with electric field strength in an un-tilted array. Although the DNA dynamics in a post array are complicated, the electrophoretic mobility results indicate that the “free path”, i.e., the average distance of ballistic trajectories of point sized particles launched from random positions in the unit cell until they intersect the next post, is a useful proxy for the detailed DNA trajectories. The analysis of the free path reveals a fundamental connection between anisotropy of the medium and DNA transport therein that goes beyond simply improving the separation device. PMID:23868490

  9. 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 gro...

  10. Simulations of Micropumps Based on Tilted Flexible Fibers

    Science.gov (United States)

    Hancock, Matthew; Elabbasi, Nagi; Demirel, Melik

    2015-11-01

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

  11. determination of determination of optimal tilt angle for maximum

    African Journals Online (AJOL)

    eobe

    The analysis showed that the best tilt angle for PV energy production is 60 if the module is fixed module ... suitable solar technology at an efficiency of 1%. Also, ... it. Thus, achieving the maximum possible performance is critical in PV power generation [14]. Installing PV modules on either a single or dual-axis trackers is one.

  12. Heater head for stirling engine

    Science.gov (United States)

    Corey, John A.

    1985-07-09

    A monolithic heater head assembly which augments cast fins with ceramic inserts which narrow the flow of combustion gas and obtains high thermal effectiveness with the assembly including an improved flange design which gives greater durability and reduced conduction loss.

  13. The effect of progressive task-oriented training on a supplementary tilt table on lower extremity muscle strength and gait recovery in patients with hemiplegic stroke.

    Science.gov (United States)

    Kim, Chang-Yong; Lee, Jung-Sun; Kim, Hyeong-Dong; Kim, June-Sun

    2015-02-01

    The purpose of this study was to determine the influence of progressive task-oriented training on a supplementary tilt table on the lower extremity (LE) muscle strength and spatiotemporal parameters of gait in subjects with hemiplegic stroke. Thirty subjects between three and nine months post stroke were included in this study. Thirty subjects were randomly allocated to a control group (CG, n1=10), experimental group I (EG1, n2=10), and experimental group II (EG2, n3=10). All of the subjects received routine therapy for half an hour, five times a week for three weeks and additionally received training on the following three different tilt table applications for 20min a day: (1) both knee belts of the tilt table were fastened (CG), (2) only the affected side knee belt of the tilt table was fastened and one-leg standing training was performed using the less-affected LE (EG1), and (3) only the affected side knee belt of the tilt table was fastened and progressive task-oriented training was performed using the less-affected LE (EG2). The effect of tilt table applications was assessed using a hand-held dynamometer for LE muscle strength and GAITRite for spatiotemporal gait data. Our results showed that there was a significantly greater increase in the strength of all LE muscle groups, gait velocity, cadence, and stride length, a decrease in the double limb support period, and an improvement in gait asymmetry in subjects who underwent progressive task-oriented training on a supplementary tilt table compared to those in the other groups. These findings suggest that progressive task-oriented training on a supplementary tilt table can improve the LE muscle strength and spatiotemporal parameters of gait at an early stage of rehabilitation of subjects with hemiplegic stroke. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. 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.

  15. 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.

  16. Slant-tilt: the visual encoding of surface orientation.

    Science.gov (United States)

    Stevens, K A

    1983-01-01

    A specific form for the internal representation of local surface orientation is proposed, which is similar to Gibson's (1950) "amount and direction of slant". Slant amount is usually quantified by the angle sigma between the surface normal and the line of sight (0 degrees less than or equal to sigma less than or equal to 90 degrees). Slant direction corresponds to the direction of the gradient of distance from the viewer to the surface, and may be defined by the image direction tau to which the surface normal would project (0 degrees less than or equal to tau less than or equal to 360 degrees). Since the direction of slant is specified by the tilt of the projected surface normal, it is referred to as surface tilt (Stevens, 1979; Marr, 1982). The two degrees of freedom of orientation are therefore quantified by slant, an angle measured perpendicular to the image plane, and tilt, an angle measured in the image plane. The slant-tilt form provides several computational advantages relative to some other proposals and is consistent with various psychological phenomena. Slant might be encoded by various means, e.g. by the cosine of the angle, by the tangent, or linearly by the angle itself. Experimental results are reported that suggest that slant is encoded by an internal parameter that varies linearly with slant angle, with resolution of roughly one part in 100. Thus we propose that surface orientation is encoded in human vision by two quantities, one varying linearly with slant angle, the other varying linearly with tilt angle.

  17. 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

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

    Science.gov (United States)

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

    2017-11-01

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

  19. Effect of tilting on cerebral hemodynamics in preterm and term infants

    NARCIS (Netherlands)

    Pichler, G; van Boetzelar, MC; Muller, W; Urlesberger, B

    2001-01-01

    Tilting is known to cause changes in hemodynamics due to hydrostatic pressure. The present study is an analysis of changes in cerebral hemodynamics measured by near infrared spectroscopy (NIRS) following tilting up and down in preterm and term infants. A significantly different effect of tilting up

  20. Axis of eye rotation changes with head-pitch orientation during head impulses about earth-vertical.

    Science.gov (United States)

    Migliaccio, Americo A; Schubert, Michael C; Clendaniel, Richard A; Carey, John P; Della Santina, Charles C; Minor, Lloyd B; Zee, David S

    2006-06-01

    The goal of this study was to assess how the axis of head rotation, Listing's law, and eye position influence the axis of eye rotation during brief, rapid head rotations. We specifically asked how the axis of eye rotation during the initial angular vestibuloocular reflex (VOR) changed when the pitch orientation of the head relative to Earth-vertical was varied, but the initial position of the eye in the orbit and the orientation of Listing's plane with respect to the head were fixed. We measured three-dimensional eye and head rotation axes in eight normal humans using the search coil technique during head-and-trunk (whole-body) and head-on-trunk (head-only) "impulses" about an Earth-vertical axis. The head was initially oriented at one of five pitch angles (30 degrees nose down, 15 degrees nose down, 0 degrees, 15 degrees nose up, 30 degrees nose up). The fixation target was always aligned with the nasooccipital axis. Whole-body impulses were passive, unpredictable, manual, rotations with peak-amplitude of approximately 20 degrees , peak-velocity of approximately 80 degrees /s, and peak-acceleration of approximately 1000 degrees /s2. Head-only impulses were also passive, unpredictable, manual, rotations with peak-amplitude of approximately 20 degrees , peak-velocity of approximately 150 degrees /s, and peak-acceleration of approximately 3000 degrees /s2. During whole-body impulses, the axis of eye rotation tilted in the same direction, and by an amount proportional (0.51 +/- 0.09), to the starting pitch head orientation (P rotation could be predicted from vectorial summation of the gains (eye velocity/head velocity) obtained for rotations about the pure yaw and roll head axes. Thus, even when the orientation of Listing's plane and eye position in the orbit are fixed, the axis of eye rotation during the VOR reflects a compromise between the requirements of Listing's law and a perfectly compensatory VOR.

  1. Head circumference (image)

    Science.gov (United States)

    Head circumference is a measurement of the circumference of the child's head at its largest area, above the eyebrows and ears and around the back of the head. During routine check-ups, the distance is measured ...

  2. Abnormal Head Position

    Science.gov (United States)

    ... Frequently Asked Questions Español Condiciones Chinese Conditions Abnormal Head Position En Español Read in Chinese What is an abnormal head posture? An abnormal or compensatory head posture occurs ...

  3. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... of the Head? What is CT Scanning of the Head? Computed tomography, more commonly known as a ... of page What are some common uses of the procedure? CT scanning of the head is typically ...

  4. 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

    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 the ....... The results provide an overview about the feasibility of modifying the bearing impedance by means of the active lubrication system, both in open-loop (fixed control signal), or closed-loop, as a function of the journal position and proportional derivative (PD) controller gains....

  5. Tilting-Pad Journal Bearings with Active Lubrication Applied as Calibrated Shakers: Theory and Experiment

    DEFF Research Database (Denmark)

    Cerda Varela, Alejandro Javier; Santos, Ilmar

    2014-01-01

    In recent years, a continuous research effort has transformed the conventional tilting-pad journal bearing into a mechatronic machine element. The addition of electromechanical elements provides the possibility of generating controllable forces over the rotor as a function of a suitable control...... directly into the bearing clearance. The injected flow is controlled by means of a servovalve. The theoretical model includes the dynamics of servovalves and pipelines using a lumped parameter approach, whereas the coupling between the hydraulic system and the bearing oil film is modeled using a modified...

  6. Head Impact Laboratory (HIL)

    Data.gov (United States)

    Federal Laboratory Consortium — The HIL uses testing devices to evaluate vehicle interior energy attenuating (EA) technologies for mitigating head injuries resulting from head impacts during mine/...

  7. Tilted-axis wobbling in odd-mass nuclei

    Science.gov (United States)

    Budaca, R.

    2018-02-01

    A triaxial rotor Hamiltonian with a rigidly aligned high-j quasiparticle is treated by a time-dependent variational principle, using angular momentum coherent states. The resulting classical energy function has three unique critical points in a space of generalized conjugate coordinates, which can minimize the energy for specific ordering of the inertial parameters and a fixed angular momentum state. Because of the symmetry of the problem, there are only two unique solutions, corresponding to wobbling motion around a principal axis and, respectively, a tilted axis. The wobbling frequencies are obtained after a quantization procedure and then used to calculate E 2 and M 1 transition probabilities. The analytical results are employed in the study of the wobbling excitations of 135Pr nucleus, which is found to undergo a transition from low angular momentum transverse wobbling around a principal axis toward a tilted-axis wobbling at higher angular momentum.

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

    Directory of Open Access Journals (Sweden)

    Li-Feng Ma

    2000-01-01

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

  9. 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. 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...

  11. 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.

  12. Simulation of effusion from targets of tilted foils

    International Nuclear Information System (INIS)

    Mustapha, B.; Nolen, J.A.; Gomes, I.C.

    2004-01-01

    Replacing a target transverse to the beam by a 10 times thinner one tilted at about 6 o from the beam direction reduces the thickness for heat transfer and diffusion by a factor of 10 while keeping the same production thickness. This concept makes the target cool faster and therefore supports higher beam power. Monte-Carlo effusion simulations of targets based on this concept were carried out to find optimum target geometries for both fast and slow diffusion materials

  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. Conformally flat tilted Bianchi Type-V cosmological models in ...

    Indian Academy of Sciences (India)

    The model starts expanding with a big-bang at М = 0 and the expansion in the model stops at М = ∞ and = -2(Т + 2)¬. The model in general represents shearing, non-rotating and tilted universe. The expansion in the model decreases as time increases. For = 1 Т = 1, we have heat conduction vector Х1 = 0 Х4 = 0. When М ...

  15. 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...... 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....

  16. Anomalous DC Hall response in noncentrosymmetric tilted Weyl semimetals

    Science.gov (United States)

    Mukherjee, S. P.; Carbotte, J. P.

    2018-03-01

    Weyl nodes come in pairs of opposite chirality. For broken time reversal symmetry (TR) they are displaced in momentum space by {Q} and the anomalous DC Hall conductivity σxy is proportional to {Q} at charge neutrality. For finite doping there are additive corrections to σxy which depend on the chemical potential as well as on the tilt (C ) of the Dirac cones and on their relative orientation. If inversion symmetry (I) is also broken the Weyl nodes are shifted in energy by an amount Q0 . This introduces further changes in σxy and we provide simple analytic formulas for these modifications for both type I (Ctype II (C>1 , overtilted) Weyl. For type I when the Weyl nodes have equal magnitude but oppositely directed tilts, the correction to σxy is proportional to the chemical potential μ and completely independent of the energy shift Q0 . When instead the tilts are parallel, the correction is linear in Q0 and μ drops out. For type II the corrections involve both μ and Q0 , are nonlinear and also involve a momentum cut off. We discuss the implied changes to the Nernst coefficient and to the thermal Hall effect of a finite Q0 .

  17. Numerical tilting compensation in microscopy based on wavefront sensing using transport of intensity equation method

    Science.gov (United States)

    Hu, Junbao; Meng, Xin; Wei, Qi; Kong, Yan; Jiang, Zhilong; Xue, Liang; Liu, Fei; Liu, Cheng; Wang, Shouyu

    2018-03-01

    Wide-field microscopy is commonly used for sample observations in biological research and medical diagnosis. However, the tilting error induced by the oblique location of the image recorder or the sample, as well as the inclination of the optical path often deteriorates the imaging quality. In order to eliminate the tilting in microscopy, a numerical tilting compensation technique based on wavefront sensing using transport of intensity equation method is proposed in this paper. Both the provided numerical simulations and practical experiments prove that the proposed technique not only accurately determines the tilting angle with simple setup and procedures, but also compensates the tilting error for imaging quality improvement even in the large tilting cases. Considering its simple systems and operations, as well as image quality improvement capability, it is believed the proposed method can be applied for tilting compensation in the optical microscopy.

  18. Ocular Causes of Abnormal Head Position: Strabismus Clinic Data

    Directory of Open Access Journals (Sweden)

    Kadriye Erkan Turan

    2017-08-01

    Full Text Available Objectives: To determine the most common ocular causes and types of abnormal head position (AHP and describe their clinical features. Materials and Methods: Patients with AHP who had been followed in the strabismus unit were retrospectively reviewed. Demographic features and orthoptic characteristics were recorded. Results: A total of 163 patients including 61 women (37.4% and 102 men (62.6%, with a mean age of 19.9±18.3 were recruited. The most common causes of AHP were determined as fourth cranial nerve palsy (33.7%, Duane retraction syndrome (21.5%, sixth cranial nerve palsy (11%, nystagmus blockage syndrome (9.8% and Brown syndrome (6.7%. Other less frequent causes were A-V pattern strabismus, comitant strabismus, thyroid orbitopathy and third cranial nerve palsy. The most common types of AHP were head tilt (45.4% and face turn (36.8%. Out of 142 patients whose visual acuity could be evaluated, 28.2% had amblyopia. The frequency of amblyopia varied depending on the diagnosis (p<0.001, while there was no relation between amblyopia and different types of AHP (p=0.497. Stereopsis and fusion could be tested in 128 patients and 43.8% of them had stereopsis and fusion. The presence of stereopsis and fusion was found to be related with the diagnosis (p=0.001, whereas it was not related with the types of AHP (p=0.580. The presence of amblyopia was not significantly associated with fusion (p=1.000 or stereopsis (p=0.602. Conclusion: There are many ocular pathologies that cause AHP. Patients with similar diagnoses may have different types of AHP. Patients may have amblyopia and impaired binocularity despite AHP. Therefore, all patients with AHP should be examined in detail and these points should be considered in the treatment plan.

  19. Assessment of forward head posture in females: observational and photogrammetry methods.

    Science.gov (United States)

    Salahzadeh, Zahra; Maroufi, Nader; Ahmadi, Amir; Behtash, Hamid; Razmjoo, Arash; Gohari, Mahmoud; Parnianpour, Mohamad

    2014-01-01

    There are different methods to assess forward head posture (FHP) but the accuracy and discrimination ability of these methods are not clear. Here, we want to compare three postural angles for FHP assessment and also study the discrimination accuracy of three photogrammetric methods to differentiate groups categorized based on observational method. All Seventy-eight healthy female participants (23 ± 2.63 years), were classified into three groups: moderate-severe FHP, slight FHP and non FHP based on observational postural assessment rules. Applying three photogrammetric methods - craniovertebral angle, head title angle and head position angle - to measure FHP objectively. One - way ANOVA test showed a significant difference in three categorized group's craniovertebral angle (P< 0.05, F=83.07). There was no dramatic difference in head tilt angle and head position angle methods in three groups. According to Linear Discriminate Analysis (LDA) results, the canonical discriminant function (Wilks'Lambda) was 0.311 for craniovertebral angle with 79.5% of cross-validated grouped cases correctly classified. Our results showed that, craniovertebral angle method may discriminate the females with moderate-severe and non FHP more accurate than head position angle and head tilt angle. The photogrammetric method had excellent inter and intra rater reliability to assess the head and cervical posture.

  20. Zero torque gear head wrench

    Science.gov (United States)

    Mcdougal, A. R.; Norman, R. M. (Inventor)

    1976-01-01

    A gear head wrench particularly suited for use in applying torque to bolts without transferring torsional stress to bolt-receiving structures is introduced. The wrench is characterized by a coupling including a socket, for connecting a bolt head with a torque multiplying gear train, provided within a housing having an annulus concentrically related to the socket and adapted to be coupled with a spacer interposed between the bolt head and the juxtaposed surface of the bolt-receiving structure for applying a balancing counter-torque to the spacer as torque is applied to the bolt head whereby the bolt-receiving structure is substantially isolated from torsional stress. As a result of the foregoing, the operator of the wrench is substantially isolated from any forces which may be imposed.

  1. Head and neck cancer

    International Nuclear Information System (INIS)

    Vogl, S.E.

    1988-01-01

    This book contains 10 chapters. Some of the titles are: Combined Surgical Resection and Irradiation for Head and Neck Cancers; Analysis of Radiation Therapy Oncology Group Head and Neck Database: Identification of Prognostic Factors and the Re-evaluation of American Joint Committee Stages; Combined Modality Approach to Head and Neck Cancer; Induction Combination Chemotherapy of Regionally Advanced Head and Neck Cancer; and Outcome after Complete Remission to Induction Chemotherapy in Head and Neck Cancer

  2. Head-wave coefficients in anisotropic media

    Science.gov (United States)

    Chapman, Chris

    2018-03-01

    Reflections and transmissions from interfaces can generate head waves. Although the kinematic properties of head waves are modelled simply using ray concepts, the dynamic properties require an extension of ray theory or the use of wave theory. Head waves are important in exploration and crustal seismology as they indicate the existence of an interface and the velocity of the generating wave. Head waves have been described in the literature for isotropic media but the extension to anisotropic media seems to be lacking. The expressions for the head-wave coefficients using ray concepts or wave theory differ, and their equality is not obvious. This paper extends the theory for head-wave coefficients to anisotropic media using both ray theory and wave theory, and generalizes the proof of equality of the two methods. Simple numerical examples confirm this equality and indicate how the head-wave results can be calculated in anisotropic media and included in a ray-tracing algorithm.

  3. Is Heading in Youth Soccer Dangerous Play?

    Science.gov (United States)

    O'Kane, John W

    2016-01-01

    Soccer is among the most popular youth sports with over 3 million youth players registered in the U.S. Soccer is unique in that players intentionally use their head to strike the ball, leading to concerns that heading could cause acute or chronic brain injury, especially in the immature brains of children. Pub Med search without date restriction was conducted in November 2014 and August 2015 using the terms soccer and concussion, heading and concussion, and youth soccer and concussion. 310 articles were identified and reviewed for applicable content specifically relating to youth athletes, heading, and/or acute or chronic brain injury from soccer. Soccer is a low-risk sport for catastrophic head injury, but concussions are relatively common and heading often plays a role. At all levels of play, concussions are more likely to occur in the act of heading than with other facets of the game. While concussion from heading the ball without other contact to the head appears rare in adult players, some data suggests children are more susceptible to concussion from heading primarily in game situations. Contributing factors include biomechanical forces, less developed technique, and the immature brain's susceptibility to injury. There is no evidence that heading in youth soccer causes any permanent brain injury and there is limited evidence that heading in youth soccer can cause concussion. A reasonable approach based on U.S. Youth Soccer recommendations is to teach heading after age 10 in controlled settings, and heading in games should be delayed until skill acquisition and physical maturity allow the youth player to head correctly with confidence.

  4. Solar ultraviolet protection provided by human head hair.

    Science.gov (United States)

    Parisi, Alfio V; Smith, Don; Schouten, Peter; Turnbull, David J

    2009-01-01

    The solar erythemal UV irradiances through human hair and the protection from UV provided by human head hair have been investigated for a solar zenith angle (SZA) range of 17-51 degrees for the conditions of a head upright in full sun, a head upright in shade and a head in full sun tilted toward the sun. The two hair lengths investigated were 49.1 +/- 7.1 mm for the short type and 109.5 +/- 5.5 mm for the long type. For the head upright in full sun, the irradiances through the hair ranged from 0.75 to 1.4 SED h(-1) for SZA protection factor (UPF) ranged from approximately 5 to 17 in full sun, with the UPF increasing with higher SZA. The longer hair provided a lower UPF than the shorter hair and for the head oriented toward the sun, there was a marginally lower UPF than for the upright head. This research shows that the UV exposure limits to the scalp through hair can be exceeded within short timeframes and provides important information to assist employers to comply with Workplace Health and Safety legislation.

  5. Study of a Car Body Tilting System Using a Variable Link Mechanism: Fundamental Characteristics of Pendulum Motion and Strategy for Perfect Tilting

    Science.gov (United States)

    Yoshida, Hidehisa; Nagai, Masao

    This paper analyzes the fundamental dynamic characteristics of a tilting railway vehicle using a variable link mechanism for compensating both the lateral acceleration experienced by passengers and the wheel load imbalance between the inner and outer rails. The geometric relations between the center of rotation, the center of gravity, and the positions of all four links of the tilting system are analyzed. Then, equations of the pendulum motions of the railway vehicle body with a four-link mechanism are derived. A theoretically discussion is given on the geometrical shapes employed in the link mechanism that can simultaneously provide zero lateral acceleration and zero wheel load fluctuation. Then, the perfect tilting condition, which is the control target of the feedforward tilting control, is derived from the linear equation of tilting motion.

  6. Head first C#

    CERN Document Server

    Stellman, Andrew

    2008-01-01

    Head First C# is a complete learning experience for object-oriented programming, C#, and the Visual Studio IDE. Built for your brain, this book covers C# 3.0 and Visual Studio 2008, and teaches everything from language fundamentals to advanced topics including garbage collection, extension methods, and double-buffered animation. You'll also master C#'s hottest and newest syntax, LINQ, for querying SQL databases, .NET collections, and XML documents. By the time you're through, you'll be a proficient C# programmer, designing and coding large-scale applications. Every few chapters you will come

  7. 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...

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    Tilt Current Meters (TCM’s) are relatively simple and inexpensive instruments for measuring currents in rivers and inthe sea. Their low cost and easy deployment means that a relatively large number of TCM’s can be deployed comparedto more conventional current meters such as Acoustic Doppler...... a number ofimportant challenges to the measurements as the hydrodynamic forcing changes and the oscillations of the TCM cannotnecessarily be averaged out as for a steady current. This study addresses some of these challenges by analyzing theperformance of a TCM in the surf zone where wave orbital motion...

  9. Edge Waves and Localization in Lattices Containing Tilted Resonators

    Directory of Open Access Journals (Sweden)

    Domenico Tallarico

    2017-06-01

    Full Text Available The paper presents the study of waves in a structured geometrically chiral solid. A special attention is given to the analysis of the Bloch-Floquet waves in a doubly periodic high-contrast lattice containing tilted resonators. Dirac-like dispersion of Bloch waves in the structure is identified, studied, and applied to wave-guiding and wave-defect interaction problems. The work is extended to the transmission problems and models of fracture, where localization and edge waves occur. The theoretical derivations are accompanied with numerical simulations and illustrations.

  10. 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...... 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...

  11. A Tilt, Soil Moisture, and Pore Water Pressure Sensor System for Slope Monitoring Applications

    Directory of Open Access Journals (Sweden)

    Rosanno de Dios

    2009-06-01

    Full Text Available This paper describes the design, implementation and characterization of a sensor network intended for monitoring of slope deformation and potential failures. The sensor network system consists of a tilt and moisture sensor column, a pore water pressure sensor column and a personal computer for data storage and processing. The tilt sensor column consists of several pipe segments containing tri-axial accelerometers and signal processing electronics. Each segment is joined together by flexible joints to allow for the column to deform and subsequently track underground movement. Capacitive-type sensors for soil moisture measurement are also included in the sensor column, which are used to measure the soil moisture at different depths. The measurements at each segment are transferred via a Controller Area Network (CAN bus, where the CAN master node is located at the top of the column above ground. The CAN master node transmits the collected data from the slave nodes via a wireless connection to a personal computer that performs data storage, processing and display via a Python-based graphical user interface (GUI. The entire system was deployed and characterized on a small-scale slope model. Slope failure was induced via water seepage and the system was demonstrated to ably measure the inclination and soil moisture content throughout the landslide event.

  12. An efficient wave extrapolation method for tilted orthorhombic media using effective ellipsoidal models

    KAUST Repository

    Waheed, Umair bin

    2014-08-01

    The wavefield extrapolation operator for ellipsoidally anisotropic (EA) media offers 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 focusing for media of orthorhombic anisotropy. Therefore, we develop effective EA models that correctly capture the kinematic behavior of the wavefield for tilted orthorhombic (TOR) media. Specifically, we compute effective source-dependent velocities for the EA model using kinematic high-frequency representation of the TOR wavefield. The effective model allows us to use the cheaper EA wavefield extrapolation operator to obtain approximate wavefield solutions for a TOR model. Despite the fact that the effective EA models are obtained by kinematic matching using high-frequency asymptotic, the resulting wavefield contains most of the critical wavefield components, including the frequency dependency and caustics, if present, with reasonable accuracy. The methodology developed here offers a much better cost versus accuracy tradeoff for wavefield computations in TOR media, particularly for media of low to moderate complexity. We demonstrate applicability of the proposed approach on a layered TOR model.

  13. Experimental and Numerical Simulation of Unbalance Response in Vertical Test Rig with Tilting-Pad Bearings

    Directory of Open Access Journals (Sweden)

    Mattias Nässelqvist

    2014-01-01

    Full Text Available In vertically oriented machines with journal bearing, there are no predefined static radial loads, such as dead weight for horizontal rotor. Most of the commercial software is designed to calculate rotordynamic and bearing properties based on machines with a horizontally oriented rotor; that is, the bearing properties are calculated at a static eccentricity. For tilting-pad bearings, there are no existing analytical expressions for bearing parameters and the bearing parameters are dependent on eccentricity and load angle. The objective of this paper is to present a simplified method to perform numerical simulations on vertical rotors including bearing parameters. Instead of recalculating the bearing parameters in each time step polynomials are used to represent the bearing parameters for present eccentricities and load angles. Numerical results are compared with results from tests performed in a test rig. The test rig consists of two guide bearings and a midspan rotor. The guide bearings are 4-pad tilting-pad bearings. Shaft displacement and strains in the bearing bracket are measured to determine the test rig’s properties. The comparison between measurements and simulated results shows small deviations in absolute displacement and load levels, which can be expected due to difficulties in calculating exact bearing parameters.

  14. The fibular head projection is of limited use as a radiographic landmark in preoperative planning of total knee arthroplasty

    Energy Technology Data Exchange (ETDEWEB)

    Matziolis, Doerte; Meiser, Marius; Matziolis, Georg [University Hospital Jena, Orthopedic Department, Eisenberg (Germany); Sieber, Norbert [Radiology Practice Eisenberg, Eisenberg (Germany); Teichgraeber, Ulf [University Hospital Jena, Institute of Diagnostic and Interventional Radiology, Eisenberg (Germany)

    2017-10-15

    The projection of the fibular head is recommended as a quality indicator of a correct radiographic projection. However, this landmark has yet to be sufficiently validated. The MRIs of 334 knee joints were included. On the MRIs, the distance between the FH and lateral tibial cortical bone was simulated in projections parallel to surgically relevant axes. Then, the Pearson correlation coefficient between the distance of the FH to the lateral tibial cortical bone and the projection plane causing this was determined. A projection of the knee joint perpendicular to Akagi's line projected the center of the fibular head on average 4.8 ± 2.9 mm laterally of the tibial cortical bone, parallel to the maximum mediolateral axis of the tibia 7.5 ± 3.4 mm, parallel to the posterior condylar axis 5.6 ± 3.6 mm and parallel to the surgical epicondylar axis 6.1 ± 3.5 mm laterally of the tibial cortical bone. An almost linear correlation was seen, with 1.9 tilting of the projection plane per mm change in distance between the fibular head and tibial cortical bone. At the same time, the interindividual scatter was over 60 . The rule of thumb for a partial overlap of the fibular head by the tibia in the case of a correct antero-posterior projection plane was also confirmed. However, a considerable interindividual variability of the position of the FH was found, which limits a conclusion regarding the quality of the radiographic projection on the basis of the position of the fibular head. (orig.)

  15. Photographic measurement of head and cervical posture when viewing mobile phone: a pilot study.

    Science.gov (United States)

    Guan, Xiaofei; Fan, Guoxin; Wu, Xinbo; Zeng, Ying; Su, Hang; Gu, Guangfei; Zhou, Qi; Gu, Xin; Zhang, Hailong; He, Shisheng

    2015-12-01

    With the dramatic growth of mobile phone usage, concerns have been raised with regard to the adverse health effects of mobile phone on spinal posture. The aim of this study was to determine the head and cervical postures by photogrammetry when viewing the mobile phone screen, compared with those in neutral standing posture. A total of 186 subjects (81 females and 105 males) aged from 17 to 31 years old participated in this study. Subjects were instructed to stand neutrally and using mobile phone as in daily life. Using a photographic method, the sagittal head and cervical postures were assessed by head tilt angle, neck tilt angle, forward head shift and gaze angle. The photographic method showed a high intra-rater and inter-rater reliability in measuring the sagittal posture of cervical spine and gaze angle (ICCs ranged from 0.80 to 0.99). When looking at mobile phone, the head tilt angle significantly increased (from 74.55° to 95.22°, p = 0.000) and the neck angle decreased (from 54.68° to 38.77°, p = 0.000). The forward head posture was also confirmed by the significantly increased head shift (from 10.90 to 13.85 cm, p = 0.000). The posture assumed in mobile phone use was significantly correlated with neutral posture (p mobile phone use. Compared to neutral standing, subjects display a more forward head posture when viewing the mobile phone screen, which is correlated with neutral posture, gaze angle and gender. Future studies will be needed to investigate a dose-response relationship between mobile phone use and assumed posture.

  16. Real-Time Acquisition of High Quality Face Sequences from an Active Pan-Tilt-Zoom Camera

    DEFF Research Database (Denmark)

    Haque, Mohammad A.; Nasrollahi, Kamal; Moeslund, Thomas B.

    2013-01-01

    expressions. Moreover, the imaging conditions like illumination, occlusion, and noise may change. These all aggregate the quality of most of the detected face images in terms of measures like resolution, pose, brightness, and sharpness. To deal with these problems this paper presents an active camera......Traditional still camera-based facial image acquisition systems in surveillance applications produce low quality face images. This is mainly due to the distance between the camera and subjects of interest. Furthermore, people in such videos usually move around, change their head poses, and facial......-based real-time high-quality face image acquisition system, which utilizes pan-tilt-zoom parameters of a camera to focus on a human face in a scene and employs a face quality assessment method to log the best quality faces from the captured frames. The system consists of four modules: face detection, camera...

  17. A customized head and neck support system

    International Nuclear Information System (INIS)

    Bentel, Gunilla C.; Marks, Lawrence B.; Sherouse, George W.; Spencer, David P.

    1995-01-01

    Purpose: To describe a customized head and neck immobilization system for patients receiving radiotherapy including a head support that conforms to the posterior contour of the head and neck. Methods: The system includes a customized headrest to support the posterior head and neck. This is fixed to a thermoplastic face mask that molds to the anterior head/face contours. The shape of these customized head and neck supports were compared to 'standard' supports. Results: This system is comfortable for the patients and appears to be effective in reproducing the setup of the treatment. Conclusions: The variability in the size and shape of the customized posterior supports exceeded that of 'standard' headrests. It is our clinical impression that the customized supports improve reproducibility and are now a standard part of our immobilization system. The quantitative analysis of the customized headrests and some commonly used 'standard' headrests suggests that the customized supports are better able to address variabilities in patient shape

  18. The Influence of Injection Pockets on the Performance of Tilting-Pad Thrust Bearings - Part I: Theory

    DEFF Research Database (Denmark)

    Heinrichson, Niels; Santos, Ilmar; Fuerst, Axel

    2007-01-01

    ) analysis of tilting-pad thrust bearings to include the effects of high-pressure injection and recesses in the bearing pads. The model is applied to the analysis of an existing bearing of large dimensions and the influence of the pocket is analyzed. In the analysis, the high-pressure oil injection used......This is Part I of a two-part series of papers describing the effects of high-pressure injection pockets on the operating conditions of tilting-pad thrust bearings. In Part I a numerical model based on the Reynolds equation is developed extending the threedimensional thermoelastohydrodynamic (TEHD...... for hydrostatic jacking is turned off (i.e., only the effect of the pocket is studied). It is shown that a shallow pocket positively influences the performance of the bearing because it has characteristics similar to those of a Rayleigh-step bearing. In Part II of the paper (Heinrichson, N., Fuerst, A...

  19. Tilt change recorded by broadband seismometer prior to small phreatic explosion of Meakan-dake volcano, Hokkaido, Japan

    Science.gov (United States)

    Aoyama, Hiroshi; Oshima, Hiromitsu

    2008-03-01

    We discovered an anomalous very long period (VLP) signal (duration: about 60 s) in the broadband seismic record of the precursory swarm of a small phreatic explosion at the Meakan-dake volcano, Hokkaido, Japan, in 2006; this signal was masked by a short-period tremor in the original velocity waveform, but a considerable DC step appeared in the displacement trace. Since such a step results from a tilt change, we interpreted the observed trace as being a combination of rotational (tilt) and translational (displacement) motions. The apparent displacement step in the VLP signal indicates subsidence of the summit crater. Owing to limited data, we attempted deflating the Mogi source and simulating the seismic record including both motions. When only rotational motion is considered, the simulated waveform explains well the general features of the observed trace. However, the combined trace has incompatible phases, suggesting that a more complicated source process should be considered.

  20. The influence of Injection Pockets on the Performance of Tilting-Pad Thrust Bearings: Part I - Theory

    DEFF Research Database (Denmark)

    Heinrichson, Niels; Santos, Ilmar; Fuerst, Axel

    2006-01-01

    This is Part I of a two-part series of papers describing the effects of high pressure injection pockets on the operating conditions of tilting-pad thrust bearings. A numerical model based on the Reynolds equation is developed extending the three dimensional thermo-elasto-hydrodynamic (TEHD......) analysis of tilting-pad thrust bearings to include the effects of high pressure injection and recesses in the bearing pad. The model is applied to the analysis of an existing bearing of large dimensions and the influence of the pocket is analyzed. It is shown that a shallow pocket positively influences...... the performance of the bearing as it has characteristics similar to those of a parallel step bearing....

  1. Fludrocortisone and sleeping in the head-up position limit the postural decrease in cardiac output in autonomic failure

    NARCIS (Netherlands)

    van Lieshout, J. J.; ten Harkel, A. D.; Wieling, W.

    2000-01-01

    Treatment with head-up tilt sleeping and low-dose fludrocortisone effectively minimizes orthostatic symptoms and increases orthostatic blood pressure in patients with neurogenic orthostatic hypotension. The aim of the present study was to examine whether the improvement in orthostatic blood pressure

  2. Research on Calculation of the IOL Tilt and Decentration Based on Surface Fitting

    OpenAIRE

    Li, Lin; Wang, Ke; Yan, Yan; Song, Xudong; Liu, Zhicheng

    2013-01-01

    The tilt and decentration of intraocular lens (IOL) result in defocussing, astigmatism, and wavefront aberration after operation. The objective is to give a method to estimate the tilt and decentration of IOL more accurately. Based on AS-OCT images of twelve eyes from eight cases with subluxation lens after operation, we fitted spherical equation to the data obtained from the images of the anterior and posterior surfaces of the IOL. By the established relationship between IOL tilt (decentrati...

  3. Spontaneous tilting after placement of the gunther-tulip inferior vena caval filter: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Tae Seok; Cha, In Ho; Seol, Hae Young; Park, Cheol Min [Guro Hospital, Korea University College of Medicine, Seoul (Korea, Republic of)

    2006-10-15

    Tilting of a deployed filter in the inferior vena cava (IVC) is a particular kind of periprocedural complication and this can reduce the filter's clot-trapping ability and increase the occlusion of the IVC at a later period. The authors report here on a case of spontaneous tilting of an inferior vena caval filter that was associated with thrombosis in the IVC within 2 weeks of the initially successful placement of the filter without tilting.

  4. Spontaneous tilting after placement of the gunther-tulip inferior vena caval filter: a case report

    International Nuclear Information System (INIS)

    Seo, Tae Seok; Cha, In Ho; Seol, Hae Young; Park, Cheol Min

    2006-01-01

    Tilting of a deployed filter in the inferior vena cava (IVC) is a particular kind of periprocedural complication and this can reduce the filter's clot-trapping ability and increase the occlusion of the IVC at a later period. The authors report here on a case of spontaneous tilting of an inferior vena caval filter that was associated with thrombosis in the IVC within 2 weeks of the initially successful placement of the filter without tilting

  5. Tidal tilts observations in the Gran Sasso underground laboratory

    International Nuclear Information System (INIS)

    Iafolla, V.; Nozzoli, S.; Milyukov, V.

    2001-01-01

    A new tilt meter, based on the technology for building a space-borne high-sensitivity accelerometer and manufactured at IFSI/CNR, has a been operating during several years in the INFN Gran Sasso underground laboratory. The results of the analysis of a three-year data set, processed with the program package ETERNA, to estimate earth tidal parameters are reported. For the best series of data (1998) tide measurement accuracies are: 0.5-1% for the M 2 (lunar principal) amplitude and 3-4% for the O 1 (lunar declination) amplitude. The tilt meter installed at a depth of 1400 m shows no clear evidence of meteorological effects. Observed tidal parameters are compared with theoretical tidal parameters predicted for a non-hydrostatic inelastic Earth model and demonstrate good agreement for the M 2 component. Due to the high accuracy of the tidal components prediction (better than 1%) tidal measurements were used to estimate the long-term stability of the instrument response

  6. Evaluation of the Thermal Effects in Tilting Pad Bearing

    Directory of Open Access Journals (Sweden)

    G. B. Daniel

    2013-01-01

    Full Text Available The analysis of thermal effects is of expressive importance in the context of rotordynamics to evaluate the behavior of hydrodynamic bearings because these effects can influence their dynamic characteristics under specific operational conditions. For this reason, a thermohydrodynamic model is developed in this work, in which the pressure distribution in the oil film and the temperature distribution are calculated together. From the pressure distribution, the velocity distribution field is determined, as well as the viscous dissipation, and consequently, the temperature distribution. The finite volume method is applied to solve the Reynolds equation and the energy equation in the thermohydrodynamic model (THD. The results show that the temperature is higher as the rotational speed increases due to the shear rate of the oil film. The maximum temperature in the bearing occurs in the overloaded pad, near the outlet boundary. The experimental tests were performed in a tilting pad journal bearing operating in a steam turbine to validate the model. The comparison between the experimental and numerical results provides a good correlation. The thermohydrodynamic lubrication developed in this assignment is promising to consistently evaluate the behavior of the tilting pad journal bearing operating in relatively high rotational speeds.

  7. Head and face reconstruction

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002980.htm Head and face reconstruction To use the sharing features on this page, please enable JavaScript. Head and face reconstruction is surgery to repair or ...

  8. Head CT scan

    Science.gov (United States)

    ... CT; Cranial CT; CT scan - skull; CT scan - head; CT scan - orbits; CT scan - sinuses; Computed tomography - ... Head CT is done in the hospital or radiology center. You lie on a narrow table that ...

  9. Head Lice: Diagnosis

    Science.gov (United States)

    ... CDC Cancel Submit Search The CDC Parasites - Lice - Head Lice Note: Javascript is disabled or is not ... please visit this page: About CDC.gov . Lice Head Lice General Information Frequently Asked Questions (FAQs) Treatment ...

  10. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... the limitations of CT Scanning of the Head? What is CT Scanning of the Head? Computed tomography, ... than regular radiographs (x-rays). top of page What are some common uses of the procedure? CT ...

  11. Head injury - first aid

    Science.gov (United States)

    ... medlineplus.gov/ency/article/000028.htm Head injury - first aid To use the sharing features on this page, ... a concussion can range from mild to severe. First Aid Learning to recognize a serious head injury and ...

  12. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... for Brain Tumors Radiation Therapy for Head and Neck Cancer Others American Stroke Association National Stroke Association ... Computer Tomography (CT) Safety During Pregnancy Head and Neck Cancer X-ray, Interventional Radiology and Nuclear Medicine ...

  13. 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)

  14. Research on calculation of the IOL tilt and decentration based on surface fitting.

    Science.gov (United States)

    Li, Lin; Wang, Ke; Yan, Yan; Song, Xudong; Liu, Zhicheng

    2013-01-01

    The tilt and decentration of intraocular lens (IOL) result in defocussing, astigmatism, and wavefront aberration after operation. The objective is to give a method to estimate the tilt and decentration of IOL more accurately. Based on AS-OCT images of twelve eyes from eight cases with subluxation lens after operation, we fitted spherical equation to the data obtained from the images of the anterior and posterior surfaces of the IOL. By the established relationship between IOL tilt (decentration) and the scanned angle, at which a piece of AS-OCT image was taken by the instrument, the IOL tilt and decentration were calculated. IOL tilt angle and decentration of each subject were given. Moreover, the horizontal and vertical tilt was also obtained. Accordingly, the possible errors of IOL tilt and decentration existed in the method employed by AS-OCT instrument. Based on 6-12 pieces of AS-OCT images at different directions, the tilt angle and decentration values were shown, respectively. The method of the surface fitting to the IOL surface can accurately analyze the IOL's location, and six pieces of AS-OCT images at three pairs symmetrical directions are enough to get tilt angle and decentration value of IOL more precisely.

  15. Research on Calculation of the IOL Tilt and Decentration Based on Surface Fitting

    Directory of Open Access Journals (Sweden)

    Lin Li

    2013-01-01

    Full Text Available The tilt and decentration of intraocular lens (IOL result in defocussing, astigmatism, and wavefront aberration after operation. The objective is to give a method to estimate the tilt and decentration of IOL more accurately. Based on AS-OCT images of twelve eyes from eight cases with subluxation lens after operation, we fitted spherical equation to the data obtained from the images of the anterior and posterior surfaces of the IOL. By the established relationship between IOL tilt (decentration and the scanned angle, at which a piece of AS-OCT image was taken by the instrument, the IOL tilt and decentration were calculated. IOL tilt angle and decentration of each subject were given. Moreover, the horizontal and vertical tilt was also obtained. Accordingly, the possible errors of IOL tilt and decentration existed in the method employed by AS-OCT instrument. Based on 6–12 pieces of AS-OCT images at different directions, the tilt angle and decentration values were shown, respectively. The method of the surface fitting to the IOL surface can accurately analyze the IOL’s location, and six pieces of AS-OCT images at three pairs symmetrical directions are enough to get tilt angle and decentration value of IOL more precisely.

  16. NUMERICAL SIMULATIONS OF NATURALLY TILTED, RETROGRADELY PRECESSING, NODAL SUPERHUMPING ACCRETION DISKS

    International Nuclear Information System (INIS)

    Montgomery, M. M.

    2012-01-01

    Accretion disks around black hole, neutron star, and white dwarf systems are thought to sometimes tilt, retrogradely precess, and produce hump-shaped modulations in light curves that have a period shorter than the orbital period. Although artificially rotating numerically simulated accretion disks out of the orbital plane and around the line of nodes generate these short-period superhumps and retrograde precession of the disk, no numerical code to date has been shown to produce a disk tilt naturally. In this work, we report the first naturally tilted disk in non-magnetic cataclysmic variables using three-dimensional smoothed particle hydrodynamics. Our simulations show that after many hundreds of orbital periods, the disk has tilted on its own and this disk tilt is without the aid of radiation sources or magnetic fields. As the system orbits, the accretion stream strikes the bright spot (which is on the rim of the tilted disk) and flows over and under the disk on different flow paths. These different flow paths suggest the lift force as a source to disk tilt. Our results confirm the disk shape, disk structure, and negative superhump period and support the source to disk tilt, source to retrograde precession, and location associated with X-ray and He II emission from the disk as suggested in previous works. Our results identify the fundamental negative superhump frequency as the indicator of disk tilt around the line of nodes.

  17. Comparative analysis of diffused solar radiation models for optimum tilt angle determination for Indian locations

    International Nuclear Information System (INIS)

    Yadav, P.; Chandel, S.S.

    2014-01-01

    Tilt angle and orientation greatly are influenced on the performance of the solar photo voltaic panels. The tilt angle of solar photovoltaic panels is one of the important parameters for the optimum sizing of solar photovoltaic systems. This paper analyses six different isotropic and anisotropic diffused solar radiation models for optimum tilt angle determination. The predicted optimum tilt angles are compared with the experimentally measured values for summer season under outdoor conditions. The Liu and Jordan model is found to exhibit t lowest error as compared to other models for the location. (author)

  18. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... Perfusion of the Head CT Angiography (CTA) Stroke Brain Tumors Computer Tomography (CT) Safety During Pregnancy Head and Neck Cancer X-ray, Interventional Radiology and Nuclear Medicine Radiation Safety Images related to Computed Tomography (CT) - Head Videos related to Computed Tomography ( ...

  19. Head, Neck, and Oral Cancer

    Medline Plus

    Full Text Available ... out more. Oral, Head and Neck Pathology Oral, Head and Neck Pathology Close to 49,750 Americans ... out more. Oral, Head and Neck Pathology Oral, Head and Neck Pathology Close to 49,750 Americans ...

  20. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... Site Index A-Z Magnetic Resonance Imaging (MRI) - Head Magnetic resonance imaging (MRI) of the head uses ... of the Head? What is MRI of the Head? Magnetic resonance imaging (MRI) is a noninvasive medical ...

  1. CT Perfusion of the Head

    Science.gov (United States)

    ... Site Index A-Z CT Perfusion of the Head Computed tomography (CT) perfusion of the head uses ... the Head? What is CT Perfusion of the Head? Computed tomography (CT) perfusion imaging shows which areas ...

  2. Head, Neck, and Oral Cancer

    Medline Plus

    Full Text Available ... Head and Neck Pathology Oral, Head and Neck Pathology Close to 49,750 Americans will be diagnosed ... Head and Neck Pathology Oral, Head and Neck Pathology Close to 49,750 Americans will be diagnosed ...

  3. Experimental study of the distillation process in a tilted cavity

    Science.gov (United States)

    Wang, Xihui; Chen, Houtao; Wang, Zhijie; Xiao, Gang

    2017-05-01

    Heat and mass transfer correlations in a basin solar still are not applicable for brine-flowing type solar still. Thermal efficiency is hard to determine explicitly due to the varying temperature of brine along the flow direction. A simple method is proposed in the present work to evaluate the performance of the brine-flowing type still through the energy balance equation of brine. Experiments in a tilted cavity which is used to simulate a brine-flowing type solar still are conducted, and it is found that thermal efficiency of the simulated still is always less than 76.3%. An empirical equation is obtained, which may provide a clue for the development of an explicit theoretical model to predict fresh water production of the brine-flowing solar still.

  4. Rain Sensor with Stacked Light Waveguide Having Tilted Air Gap

    Directory of Open Access Journals (Sweden)

    Kyoo Nam Choi

    2014-01-01

    Full Text Available Vehicle sensor to detect rain drop on and above waveguide utilizing light deflection and scattering was realized, keeping wide sensing coverage and sensitivity to detect mist accumulation. Proposed sensor structure under stacked light wave guide consisted of light blocking fixture surrounding photodetector and adjacent light source. Tilted air gap between stacked light waveguide and light blocking fixture played major role to increase sensitivity and to enhance linearity. This sensor structure eliminated complex collimating optics, while keeping wide sensing coverage using simple geometry. Detection algorithm based on time-to-intensity transformation process was used to convert raining intensity into countable raining process. Experimental result inside simulated rain chamber showed distinct different response between light rain and normal rain. Application as automobile rain sensor is expected.

  5. 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.

  6. Assessment of the Relationship between Pelvic Tilt and the Sacro-Femoral-Pubic Angle in Middle-Aged and Elderly Asian Individuals.

    Science.gov (United States)

    Kitagawa, Takanori; Iizuka, Yoichi; Kobayashi, Hiroki; Mieda, Tokue; Tsunoda, Daisuke; Yamamoto, Atsushi; Tajika, Tsuyoshi; Iizuka, Haku; Takagishi, Kenji

    2017-12-01

    Cross-sectional study. The purpose of this study was to evaluate the correlation between pelvic tilt (PT) and the sacro-femoral-pubic (SFP) angle, which is easier to identify than PT, in middle-aged and elderly Asian subjects from the general population. Measuring PT is important in the diagnosis and treatment of adult spinal deformity. However, identifying femoral heads, which are necessary to determine PT, using sagittal radiographs is often difficult. Standing coronal and sagittal pelvic radiographs of individuals aged more than 50 years were taken during a local medical examination. The subjects were divided into female, male, and total groups at the time of evaluation. Linear regression analysis was performed to investigate the relationship between PT and the SFP angle, which were obtained from the X-rays. The present study included 291 subjects. There were no statistically significant differences between the left and right SFP angles, and there was gender difference regarding the SFP angle. However, a gender difference was observed regarding PT. The correlation between PT and the SFP angle was substantiated in each group. Pearson's correlation coefficients between PT and the SFP angle in the total, female, and male groups were 0.696, 0.853, and 0.619, respectively. In the linear regression analysis, PT was calculated as follows: PT=60.1-0.77×(SFP angle) in the total group, PT=62.8-0.80×(SFP angle) in the female group, and PT=51.5-0.64×(SFP angle) in the male group. A significant correlation between PT and the SFP angle was observed in middle-aged and elderly Asian subjects from the general population.

  7. Definition and analytical evaluation of a power management system for tilt-rotor aircraft

    Science.gov (United States)

    Morris, J. J.; Alexander, H. R.

    1978-01-01

    The paper reviews the special design criteria which apply to power management in a tilt-rotor aircraft. These include the need for accurate and fast control of rpm and thrust, while accounting for the dynamic interactions between rotor systems caused by cross-shafting and aircraft lateral/directional response. The power management system is also required to provide acceptable high speed sensitivity to longitudinal turbulence. It is shown that the criteria can best be met using a single governor adjusting the collective pitch by an amount proportional to a combination of the average rpm and the integral of the average rpm of the two rotors. This system is evaluated and compared with other candidate systems in hover and cruise flight.

  8. Cone-beam mammo-computed tomography from data along two tilting arcs

    International Nuclear Information System (INIS)

    Zeng Kai; Yu Hengyong; Fajardo, Laurie L.; Wang Ge

    2006-01-01

    Over the past several years there has been an increasing interest in cone-beam computed tomography (CT) for breast imaging. In this article, we propose a new scheme for theoretically exact cone-beam mammo-CT and develop a corresponding Katsevich-type reconstruction algorithm. In our scheme, cone-beam scans are performed along two tilting arcs to collect a sufficient amount of information for exact reconstruction. In our algorithm, cone-beam data are filtered in a shift-invariant fashion and then weighted backprojected into the three-dimensional space for the final reconstruction. Our approach has several desirable features, including tolerance of axial data truncation, efficiency in sequential/parallel implementation, and accuracy for quantitative analysis. We also demonstrate the system performance and clinical utility of the proposed technique in numerical simulations

  9. Two-stream instability analysis for propagating charged particle beams with a velocity tilt

    Directory of Open Access Journals (Sweden)

    D. V. Rose

    2007-03-01

    Full Text Available The linear growth of the two-stream instability for a charged-particle beam that is longitudinally compressing as it propagates through a background plasma (due to an applied velocity tilt is examined. Detailed, 1D particle-in-cell (PIC simulations are carried out to examine the growth of the wave packet produced by a small amplitude density perturbation in the background plasma. Recent analytic and numerical work by Startsev and Davidson [Phys. Plasmas 13, 062108 (2006PHPAEN1070-664X10.1063/1.2212807] predicted reduced linear growth rates, which are indeed observed in the PIC simulations. Here, small-signal asymptotic gain factors are determined in a semianalytic analysis and compared with the simulation results in the appropriate limits. Nonlinear effects in the PIC simulations, including wave breaking and particle trapping, are found to limit the linear growth phase of the instability for both compressing and noncompressing beams.

  10. OCULAR MANIFESTATIONS OF HEAD INJURIES

    Directory of Open Access Journals (Sweden)

    Kanukollu Venkata Madusudana Rao

    2016-12-01

    Full Text Available BACKGROUND This prospective study aimed to evaluate the incidence of ocular manifestations in head injury and their correlation with the intracranial lesions. MATERIALS AND METHODS A total of 108 consecutive cases of closed head injury admitted in the neurosurgical ward of a tertiary teaching hospital underwent a thorough ophthalmic assessment. Clinical examination, radiological imaging and Glasgow Coma Scale (GCS were applied to grade the severity of injury. RESULTS Total number of 108 patients of head injury were examined of which 38 patients had ocular manifestations (35.18%. Of these, 85.18% were males, 84% of injuries were due to road traffic accidents and 16% were due to fall from a height. The ocular manifestations were as follows- Orbital complications were seen in 6 patients (15.8%. Anterior segment manifestations included black eyes seen in 10 patients (26.3%, subconjunctival haemorrhage in 10.5% of patients (4 patients, corneal involvement in 21% of patients (8 patients and pupillary involvement in 50% of patients (19 patients. Posterior segment manifestations were seen in 26.3% of patients (10 patients and were as follows- Purtscher’s retinopathy in 2 patients and optic atrophy in 5 patients. Cranial nerve palsies were seen in 15 patients (39.47% and supranuclear movement disorders were seen in 3 patients (8%. CONCLUSION Even though, neurosurgeons perform comprehensive clinical examination including eye examination, the main purpose is limited to aid topical diagnosis of neurological lesions. This study emphasises the importance of a detailed eye examination by an ophthalmologist to prevent irreversible visual loss in addition to aiding in the neurological diagnosis. Pupillary involvement, papilloedema and ocular motor paresis pointed to a more severe head injury. This observational prospective study helped us to correlate the severity of head injuries in association with ocular findings in patients admitted in neurosurgical ward

  11. A Psychometric Investigation of Gender-Tilted Families: Implications for Family Therapy.

    Science.gov (United States)

    Falconer, Clark W.; And Others

    1990-01-01

    Obtained self-reports from 40 couples from gender-tilted families, families which have several children of same sex. Parents of boys reported higher levels of family conflict and lower satisfaction with their families than did parents of girls. Parents of male-tilted families expressed more masculine sex-role orientations, greater personal…

  12. 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...

  13. 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.

  14. 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°.

  15. Switching PD-based sliding mode control for hovering of a tilting-thruster underwater robot.

    Science.gov (United States)

    Jin, Sangrok; Bak, Jeongae; Kim, Jongwon; Seo, TaeWon; Kim, Hwa Soo

    2018-01-01

    This paper presents a switching PD-based sliding mode control (PD-SMC) method for the 6-degree-of-freedom (DOF) hovering motion of the underwater robot with tilting thrusters. Four thrusters of robot can be tilted simultaneously in the horizontal and vertical directions, and the 6-DOF motion is achieved by switching between two thruster configurations. Therefore, the tilting speed of thruster becomes the most essential parameter to determine the stability of hovering motion. Even though the previous PD control ensures stable hovering motion within a certain ranges of tilting speed, a PD-SMC is suggested in this paper by combining PD control with sliding mode control in order to achieve acceptable hovering performance even at the much lower tilting speeds. Also, the sign function in the sliding mode control is replaced by a sigmoid function to reduce undesired chattering. Simulations show that while PD control is effective only for tilting duration of 600 ms, the PD-based sliding mode control can guarantee the stable hovering motion of underwater robot even for the tilting duration of up to 1500 ms. Extensive experimental results confirm the hovering performance of the proposed PD-SMC method is much superior to that of PD method for much larger tilting durations.

  16. The effect of tilt angle on the performance of evacuated tube solar air ...

    African Journals Online (AJOL)

    The evacuated tube solar air collector had different collector tilt angles from the horizontal with the one inclined at 30° and 45°. Experimental results revealed that tilt angle had significant influence on the thermal performance of the evacuated tube solar air collector along with or without reflector. Experiments also showed ...

  17. Performance verification of focus variation and confocal microscopes measuring tilted ultra-fine surfaces

    DEFF Research Database (Denmark)

    Quagliotti, Danilo; Baruffi, Federico; Tosello, Guido

    2016-01-01

    The behaviour of two optical instruments, scilicet a laser scanning confocal microscope and a focus-variation microscope, was investigated considering measurements of tilted surfaces. The measured samples were twelve steel artefacts for mould surface finish reference, covering Sa roughness...... parameter in the range (101—103) nm. The 3D surface texture parameters considered were Sa, Sq and Sdq. The small working distance of the confocal microscope objectives influenced the measurement setup, preventing from selecting a high tilting angle. The investigation was carried out comparing measurements...... of flat surfaces (0° tilt) with measurements of 12.5° tilted surfaces. The confocal microscope results showed a high sensitivity to tilting due to the laser beam reflection on the metal surfaces. The focus variation microscope results were more robust with respect to the considered angular variation...

  18. Comparison of marginal bone loss and implant success between axial and tilted implants in maxillary All-on-4 treatment concept rehabilitations after 5 years of follow-up.

    Science.gov (United States)

    Hopp, Milena; de Araújo Nobre, Miguel; Maló, Paulo

    2017-10-01

    There is need for more scientific and clinical information on longer-term outcomes of tilted implants compared to implants inserted in an axial position. Comparison of marginal bone loss and implant success after a 5-year follow-up between axial and tilted implants inserted for full-arch maxillary rehabilitation. The retrospective clinical study included 891 patients with 3564 maxillary implants rehabilitated according to the All-on-4 treatment concept. The follow-up time was 5 years. Linear mixed-effect models were performed to analyze the influence of implant orientation (axial/tilted) on marginal bone loss and binary logistic regression to assess the effect of patient characteristics on occurrence of marginal bone loss >2.8 mm. Only those patients with measurements of at least one axial and one tilted implant available were analyzed. This resulted in a data set of 2379 implants (1201 axial, 1178 tilted) in 626 patients (=reduced data set). Axial and tilted implants showed comparable mean marginal bone losses of 1.14 ± 0.71 and 1.19 ± 0.82 mm, respectively. Mixed model analysis indicated that marginal bone loss levels at 5 years follow up was not significantly affected by the orientation (axial/tilted) of the implants in the maxillary bone. Smoking and female gender were associated with marginal bone loss >2.8 mm in a logistic regression analysis. Five-year implant success rates were 96%. The occurrence of implant failure showed to be statistically independent from orientation. Within the limitations of this study and considering a follow-up time of 5 years, it can be concluded that tilted implants behave similarly with regards to marginal bone loss and implant success in comparison to axial implants in full-arch rehabilitation of the maxilla. Longer-term outcomes (10 years +) are needed to verify this result. © 2017 Wiley Periodicals, Inc.

  19. In-vitro hemodynamics of stented bioprosthetic heart valves in the tilted implantation position.

    Science.gov (United States)

    Babin-Ebell, Joerg; Sievers, Hans H; Misfeld, Martin; Runge, Maike; Vogt, Paul Robert; Scharfschwerdt, Michael

    2008-09-01

    Although, in small aortic annulus or aortic annulus calcification, it is recommended that valves are implanted in a tilted position, mechanical valves show impaired hemodynamic performance when positioned in this way. To date, no investigations have been conducted with biological valves implanted in a tilted position. Measurements were performed in a pulsatile flow simulator. The aortic roots were mounted in a fluid reservoir and tested with bioprosthetic valves implanted in the regular position (21 mm; n = 7) or at a 200 tilt (23 mm; n = 7). Additional 21 mm valves were implanted in both positions with a systemic pressure of 120/80 mmHg. Subsequently, the valves were implanted into a glass model and flow visualization monitored by adding air bubbles illuminated with a laser diode. The 21 mm valves showed a slightly higher transvalvular gradient in the tilted than in the regular position, while 23 mm valves in a tilted position showed a lower gradient than 21 mm valves in the regular position. Flow in the regular position was seen to be straight and central, but in the tilted position was diverted and impacted on the aortic wall. Vortex formation in the tilted position was more pronounced than in the regular position, with certain low-flow areas being observed. The implantation of a one size-larger bioprosthetic valve at a 20 degree tilt in a small aortic root resulted in a slight reduction in transvalvular gradient compared to a smaller valve implanted in the regular position. Whilst mechanical valve performance is markedly compromised in the tilted position, the bioprosthetic valve showed only minor impairment of transvalvular pressure gradient due to tilting, and this was overcompensated by the larger valve size. However, the advantage of a greater orifice area must be traded against the consequences of the observed flow disturbances.

  20. Head Injuries in Soccer.

    Science.gov (United States)

    Myrick, Karen M

    2016-07-01

    Soccer is currently the most popular and fastest growing sport worldwide, with approximately 265 million registered soccer players existing around the world. The popularity of the sport, coupled with the high incidence of 18.8-21.5 head injuries per 1,000 player hours reported, make it essential that clinicians, coaches, and the athletes, have a solid understanding of head injuries. The successful rehabilitation of athletes with head injuries relies upon early and accurate identification strategies and implementation of appropriate return to play measures across all areas in the continuum of care. Soccer is a frequently played sport, and head injuries are common. Therefore, it is imperative that clinicians, coaches, and the athletes themselves have a solid understanding of head injury prevention, diagnosis, and treatment options. The purpose of this article was to provide rehabilitation nurses with current information regarding frequently occurring head injuries in the widespread sport of soccer. © 2015 Association of Rehabilitation Nurses.

  1. Tilted Implants for Full-Arch Rehabilitations in Completely Edentulous Maxilla: A Retrospective Study

    Directory of Open Access Journals (Sweden)

    Nicolò Cavalli

    2012-01-01

    Full Text Available Purpose. The aims of this study were to assess the treatment outcome of immediately loaded full-arch fixed bridges anchored to both tilted and axially placed implants in the edentulous maxilla and to evaluate the incidence of biological and prosthetic complications. Materials and Methods. Thirty-four patients (18 women and 16 men were included in the study. Each patient received a maxillary full-arch fixed bridge supported by two axial implants and two distal tilted implants. A total of 136 implants were inserted. Loading was applied within 48 hours of surgery and definitive restorations were placed 4 to 6 months later. Patients were scheduled for followup at 6, 12, 18, and 24 months and annually up to 5 years. At each followup plaque level and bleeding scores were assessed and every complication was recorded. Results. The overall follow-up range was 12 to 73 months (mean 38.8 months. No implant failures were recorded to date, leading to a cumulative implant survival rate of 100%. Biological complications were recorded such as alveolar mucositis (11.8% patients, peri-implantitis (5.9% patients, and temporomandibular joint pain (5.9% patients. The most common prosthetic complications were the fracture or detachment of one or multiple acrylic teeth in both the temporary (20.6% patients and definitive (17.7% patients prosthesis and the minor acrylic fractures in the temporary (14.7% patients and definitive (2.9% patients prosthesis. Hygienic complications occurred in 38.2% patients. No patients’ dissatisfactions were recorded. Conclusions. The high cumulative implant survival rate indicates that this technique could be considered a viable treatment option. An effective recall program is important to early intercept and correct prosthetic and biologic complications in order to avoid implant and prosthetic failures.

  2. The semiology of tilt-induced reflex syncope in relation to electroencephalographic changes.

    Science.gov (United States)

    van Dijk, J Gert; Thijs, Roland D; van Zwet, Erik; Tannemaat, Martijn R; van Niekerk, Julius; Benditt, David G; Wieling, Wouter

    2014-02-01

    Syncope is defined as transient loss of consciousness as a result of cerebral hypoperfusion. Electroencephalography during syncope shows either a 'slow-flat-slow' or a 'slow' pattern. The first is believed to denote more severe hypoperfusion. Although the diagnosis of vasovagal syncope relies primarily on history taking, there is limited evidence regarding the relative importance of various clinical features, and none that relate them to the severity of electroencephalographic changes. The aim of this investigation was to study symptoms, signs and electroencephalographic changes with a 1 s resolution using electroencephalography and video data in 69 cases of tilt-induced vasovagal syncope. The main finding was that flattening of the electroencephalograph indicated more profound circulatory changes: the 'slow-flat-slow' group had a lower minimum blood pressure, longer maximum RR-interval, contained more cases with asystole and had a longer duration of loss of consciousness than the 'slow' group. Second, we describe a range of signs, including some that have rarely been reported in syncope, e.g. oral automatisms. Third, signs occurred at different rates depending on electroencephalographic flattening, suggesting a classification of syncopal signs. Type A signs (e.g. loss of consciousness, eye opening and general stiffening) develop during the first slow phase, stay present during flattening and stop in the second slow phase. Type B (particularly myoclonic jerks) occur when the electroencephalograph is slow but not flat: their abolition with electroencephalographic flattening suggests dependence on cortical activity. Type C signs (making sounds, roving eye movements and stertorous breathing) occur only in the flat phase, whereas type D (dropping the jaw and snoring) may occur either in slow or flat phases. In conclusion, our findings provide a detailed assessment of clinical symptoms in relation to electroencephalographic (EEG) changes during tilt-induced syncope.

  3. Analysis of the In-core Quadrant Power Tilt affected by Burned Fuel Shuffles of WEC Type NPPs in Republic of Korea

    Energy Technology Data Exchange (ETDEWEB)

    Son, Seung-beom; Jeon, Jeong-pyo; Song, Han-seung; Seong, Ki-bong; Lim, Chae-joon [KEPCO Nuclear Fuel, Daejeon (Korea, Republic of)

    2016-10-15

    This paper presents the designed Burned Fuel Shuffles (BFS) and the related results of measured In-core Quadrant Power Tilt (IQPT) in recent cycles of WEC (Westinghouse Electric Company) type NPPs (Nuclear Power Plants) in Republic of Korea. And the IQPT sensitivity results affected by BFS are also analyzed. Excessive core Quadrant Power Tilt (QPT) causes unreliability about designed power distribution and increases peaking factors in the affected core quadrants. The peaking factors are under surveillance during the cycle for the safe operation and the Quadrant Power Tilt Ratio (QPTR) is covered by the Technical Specifications. Possible causes for QPT include manufacturing tolerance, asymmetric core configurations, operating conditions, and so forth, but the actual cause of specific core tilts frequently cannot be definitively identified. But nuclear designer continuously try to minimize the QPT by the general control of burned fuel distribution in a reload core. In this study, the general guidelines of BFSP for effective mitigation of IQPT were introduced by references and the actual states of designed BFSP were analyzed for WEC type plant operating in the Republic of Korea. Results revealed that the BFSP was applied within appropriate level, which keeps IQPT below the level of guideline during the operations. Also, the correlation between BFSP of category 1/3 and IQPT were quantitatively confirmed by the sensitivity analysis concerned with the change of BFSP.

  4. Drugs Approved for Head and Neck Cancer

    Science.gov (United States)

    This page lists cancer drugs approved by the Food and Drug Administration (FDA) for head and neck cancer. The list includes generic names and brand names. The drug names link to NCI’s Cancer Drug Information summaries.

  5. Peripheral Microvascular Responses to Whole-Body Tilting, G(z) Centrifugation, and Lower Body Negative Pressure Stresses in Humans

    Science.gov (United States)

    Breit, G. A.; Watenpaugh, D. E.; Buckley, T. M.; Ballard, R. E.; Murthy, G.; Hargens, A. R.

    1994-01-01

    The response of the cutaneous microcirculation to orthostatic stress varies along the length of the body due to the interaction of central controls with regional responses to local blood pressure. We hypothesize that artificial orthostatic stresses such as Gz centrifugation and LBNP differ from whole-body tilting in terms of the distribution of microvascular blood flow. Cutaneous microvascular flows were measured by laser Doppler flowmetry at the neck, thigh, and leg of 15 normal subjects. Volunteers underwent stepwise head-up tilt (HUT) and short- and long-arm centrifugation protocols from supine control (0 Gz) to 0.2, 0.4, 0.6, 0.8, 1.0, 0.8, 0.6, 0.4, 0.2, and 0 Gz at the feet, for 30-s periods with 10-s transitions between levels. The same subjects underwent a corresponding supine LBNP protocol, up to 100 mmHg (in 20 mmHg increments) and back to zero pressure, which produced transmural pressure across blood vessels in the foot approximately equal to the HUT protocol. In general, application of all orthostatic stresses produced significant flow reductions in the lower body (p less than 0.05) and inconsistent changes in the neck. At low levels of each stress (0.4 Gz, 40 mmHg), LBNP generated the greatest relative reduction in flow in the lower body (-66.9+/-5.7%, thigh; -60.6 +/-5.7%, leg, mean +/- SE). HUT caused a less severe flow reduction than LBNP at the thigh and leg (-39.9 +/- 8.1% and -55.9+/-4.8%), while the effects induced by both forms of centrifugation were the least profound. Higher levels of each stress generally resulted in similar responses. These responses exhibit a consistent relationship to hypothesized changes in local microvascular transmural pressure, suggesting that myogenic and veno-arteriolar reflexes play a significant role in determining microvascular perfusion during orthostatic stress.

  6. 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.

  7. 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.

  8. 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.

  9. Twenty-degree-tilt radiography for evaluation of lateral humeral condylar fracture in children

    International Nuclear Information System (INIS)

    Imada, Hideaki; Tanaka, Ryuji; Itoh, Yohei; Kishi, Kazuhiko

    2010-01-01

    To investigate the efficacy of '20 -tilt anteroposterior (A-P) radiography' in the assessment of lateral condylar fractures of the distal humerus. Eighteen children with lateral humeral condylar fractures were studied. Every child underwent conventional A-P and lateral radiography, and six children underwent multi-detector computed tomography (MDCT). For the investigation of 20 -tilt radiography, ten children with lateral humeral condylar fractures had conventional and 20 -tilt A-P and lateral radiography both preoperatively and postoperatively. Fragment dislocation was measured at the lateral and medial margins of the fracture on both the conventional A-P and 20 -tilt A-P radiographs. The lateral condylar fragment was triangular and was most prominent posteriorly. The fracture line was typically tilted approximately 20 to a reference line perpendicular to the long axis of the humerus in the lateral view. The extent of dislocation at the lateral and medial margins of the fracture site by 20 -tilt A-P radiography (9.3 ± 3.6 mm and 5.6 ± 2.5 mm) was significantly wider than that measured by the conventional method (6.8 ± 4.1 mm and 2.0 ± 1.5 mm), which may influence treatment. Twenty-degree-tilt A-P radiography may more precisely demonstrate fragment dislocation than standard radiographs and may influence patient treatment. (orig.)

  10. Comparative study of absorption in tilted silicon nanowire arrays for photovoltaics.

    Science.gov (United States)

    Kayes, Md Imrul; Leu, Paul W

    2014-01-01

    Silicon nanowire arrays have been shown to demonstrate light trapping properties and promising potential for next-generation photovoltaics. In this paper, we show that the absorption enhancement in vertical nanowire arrays on a perfectly electric conductor can be further improved through tilting. Vertical nanowire arrays have a 66.2% improvement in ultimate efficiency over an ideal double-pass thin film of the equivalent amount of material. Tilted nanowire arrays, with the same amount of material, exhibit improved performance over vertical nanowire arrays across a broad range of tilt angles (from 38° to 72°). The optimum tilt of 53° has an improvement of 8.6% over that of vertical nanowire arrays and 80.4% over that of the ideal double-pass thin film. Tilted nanowire arrays exhibit improved absorption over the solar spectrum compared with vertical nanowires since the tilt allows for the excitation of additional modes besides the HE 1m modes that are excited at normal incidence. We also observed that tilted nanowire arrays have improved performance over vertical nanowire arrays for a large range of incidence angles (under about 60°).

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

    International Nuclear Information System (INIS)

    Madhav, P; Crotty, D J; Tornai, M P; McKinley, R L

    2009-01-01

    A compact dedicated 3D breast SPECT-CT (mammotomography) system is currently under development. In its initial prototype, the cone-beam CT sub-system is restricted to a fixed-tilt circular rotation around the patient's pendant breast. This study evaluated stationary-tilt angles for the CT sub-system that will enable maximal volumetric sampling and viewing of the breast and chest wall. Images of geometric/anthropomorphic phantoms were acquired using various fixed-tilt circular and 3D sinusoidal trajectories. The iteratively reconstructed images showed more distortion and attenuation coefficient inaccuracy from tilted cone-beam orbits than from the complex trajectory. Additionally, line profiles illustrated cupping artifacts in planes distal to the central plane of the tilted cone-beam, otherwise not apparent for images acquired with complex trajectories. This indicates that undersampled cone-beam data may be an additional cause of cupping artifacts. High-frequency objects could be distinguished for all trajectories, but their shapes and locations were corrupted by out-of-plane frequency information. Although more acrylic balls were visualized with a fixed-tilt and nearly flat cone-beam at the posterior of the breast, 3D complex trajectories have less distortion and more complete sampling throughout the reconstruction volume. While complex trajectories would ideally be preferred, negatively fixed-tilt source-detector configuration demonstrates minimally distorted patient images.

  12. Do tilt-in-space wheelchairs increase occupational engagement: a critical literature review.

    Science.gov (United States)

    Harrand, Jenny; Bannigan, Katrina

    2016-01-01

    A wheelchair can enhance the quality of life of an individual with limited mobility, poor trunk control and stability, by enabling activity and participation and so occupational engagement. High specification wheelchairs which can tilt-in-space enable the position of users to be altered to suit activity and context. Despite tilt-in-space wheelchairs being expensive little is known about their therapeutic value. A critical literature review of the evidence was undertaken to evaluate whether the use of tilt-in-space increases occupational engagement. A wide ranging search strategy identified 170 articles which were screened using inclusion criteria. The eligible literature (n = 6) was analysed thematically using open coding. The majority of the participants used tilt-in-space but the data was too heterogeneous to combine. Measures of occupational engagement were not used so the therapeutic value could not be assessed. There is a lack of high quality evidence about the therapeutic benefits of tilt-in-space wheelchairs. Given the expense associated with providing these wheelchairs, and the increase in their provision, research is needed to justify provision of high specification wheelchairs to meet the occupational needs of users within the limited resources of health and social care. Implications for Rehabilitation Tilt-in-space wheelchairs. Wheelchairs are an important and essential assistive device for promoting independence and function. Suggests there are benefits for tilt-in-space wheelchairs. Identifies the need for additional large scale research.

  13. Research on Method of Photoelectric Measurement for Tilt Angle of Scanning Mirror of Infrared Earth Sensor

    International Nuclear Information System (INIS)

    Xu, X P; Zhang, G Y; Zhang, N; Wang, L Y

    2006-01-01

    Tilt angle of scanning mirror is one of the important qualifications of performance measurement on the earth surface for swing scanning mode infrared the earth sensor. In order to settle the problem of measuring the tilt angle of scanning mirror in dynamic, real-time and non-contact, based on laser inspecting technology and CCD probing technology, a method of laser dynamical measurement for tilt angle of scanning mirror of the infrared earth sensor is presented. The measurement system developed in this paper can accomplish the dynamic and static laser non-contact measurement for the parameters of scanning mirror such as tilt angle, swing frequency, etc. In this paper the composition and overall structure of system are introduced. Emphasis on analyzing and discussing the theory of dynamically measuring tilt angle of scanning mirror, the problems of data processing and error correction are settled by established mathematic model of system. The accuracy of measurement system is verified by experiment, the results indicated that measurement range of system for tilt angle is 0∼±12 0 , accuracy of dynamic and static measurement is less than ±0.05 0 , this method of dynamically measuring tilt angle is suitable

  14. Early management of head injury in adults in primary care

    Directory of Open Access Journals (Sweden)

    Liew Boon Seng

    2017-04-01

    Full Text Available Head injury is common and preventable. Assessment of the head injury patient includes airway, cervical spine protection, breathing, circulation, haemorrhage control and the Glasgow Coma Scale. Hypotension, hypoxia, hypocarbia and hypercarbia should be avoided by continuous monitoring of vital signs and hourly head chart to prevent secondary brain injury. This paper aims to assist primary healthcare providers to select the appropriate patient for transfer and imaging for further management of head injury.

  15. Combined Influence of Visual Scene and Body Tilt on Arm Pointing Movements: Gravity Matters!

    Science.gov (United States)

    Scotto Di Cesare, Cécile; Sarlegna, Fabrice R.; Bourdin, Christophe; Mestre, Daniel R.; Bringoux, Lionel

    2014-01-01

    Performing accurate actions such as goal-directed arm movements requires taking into account visual and body orientation cues to localize the target in space and produce appropriate reaching motor commands. We experimentally tilted the body and/or the visual scene to investigate how visual and body orientation cues are combined for the control of unseen arm movements. Subjects were asked to point toward a visual target using an upward movement during slow body and/or visual scene tilts. When the scene was tilted, final pointing errors varied as a function of the direction of the scene tilt (forward or backward). Actual forward body tilt resulted in systematic target undershoots, suggesting that the brain may have overcompensated for the biomechanical movement facilitation arising from body tilt. Combined body and visual scene tilts also affected final pointing errors according to the orientation of the visual scene. The data were further analysed using either a body-centered or a gravity-centered reference frame to encode visual scene orientation with simple additive models (i.e., ‘combined’ tilts equal to the sum of ‘single’ tilts). We found that the body-centered model could account only for some of the data regarding kinematic parameters and final errors. In contrast, the gravity-centered modeling in which the body and visual scene orientations were referred to vertical could explain all of these data. Therefore, our findings suggest that the brain uses gravity, thanks to its invariant properties, as a reference for the combination of visual and non-visual cues. PMID:24925371

  16. Accuracy and head positioning effects on measurements of anterior tooth length using 3-dimensional and conventional dental panoramic radiography.

    Science.gov (United States)

    Kitai, Noriyuki; Murabayashi, Manabu; Sugimoto, Hiroshi; Fujiwara, Atsushi; Tome, Wakako; Katsumata, Akitoshi

    2017-03-01

    The purposes of this study were to examine the accuracy and the head positioning effects on measurements of anterior tooth length using 3-dimensional (3D) and conventional dental panoramic radiography and to investigate whether 3D panoramic radiography is suitable for the evaluation of anterior tooth length. A simulated human head was radiographed at 4, 8, and 12 mm displaced positions, and at 5°, 10°, and 15° tilted positions from the standard head position using 3D and conventional panoramic radiography, and also using cone-beam computed tomography. Anterior tooth lengths were measured on the panoramic and cone-beam computed tomography images. The values for the standard head position in the panoramic radiographs were defined as the standard values. Measurement error was defined as the standard value minus the cone-beam computed tomography value on each panoramic radiograph. The head position ratio of the measurement value to the standard value at each head position was calculated. Measurement errors for the 3D panoramic radiographs were significantly smaller than those for the conventional panoramic radiographs. In the 3D panoramic radiographs, the head position ratios at the 4, 8, and 12 mm displaced positions and at the 5° tilted position were within ±5% of the standard value. Three-dimensional panoramic radiography is suitable for the quantitative evaluation of anterior tooth length with high accuracy. Copyright © 2017 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

  17. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... Computed tomography (CT) of the head uses special x-ray equipment to help assess head injuries, severe headaches, ... is a diagnostic medical test that, like traditional x-rays, produces multiple images or pictures of the inside ...

  18. Quantum carpets in a one-dimensional tilted optical lattices

    Science.gov (United States)

    Parra Murillo, Carlos Alberto; Muã+/-Oz Arias, Manuel Humberto; Madroã+/-Ero, Javier

    A unit filling Bose-Hubbard Hamiltonian embedded in a strong Stark field is studied in the off-resonant regime inhibiting single- and many-particle first-order tunneling resonances. We investigate the occurrence of coherent dipole wavelike propagation along an optical lattice by means of an effective Hamiltonian accounting for second-order tunneling processes. It is shown that dipole wave function evolution in the short-time limit is ballistic and that finite-size effects induce dynamical self-interference patterns known as quantum carpets. We also present the effects of the border right after the first reflection, showing that the wave function diffuses normally with the variance changing linearly in time. This work extends the rich physical phenomenology of tilted one-dimensional lattice systems in a scenario of many interacting quantum particles, the so-called many-body Wannier-Stark system. The authors acknownledge the finantial support of the Universidad del Valle (project CI 7996). C. A. Parra-Murillo greatfully acknowledges the financial support of COLCIENCIAS (Grant 656).

  19. 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.

  20. Ferromagnetism controlled by electric field in tilted phosphorene nanoribbon

    Science.gov (United States)

    Farooq, M. Umar; Hashmi, Arqum; Hong, Jisang

    2016-01-01

    Study on phosphorene nanoribbon was mostly focused on zigzag and armchair structures and no ferromagnetic ground state was observed in these systems. Here, we investigated the magnetic property of tilted black phosphorene nanoribbons (TPNRs) affected by an external electric field. We also studied the edge passivation effect on the magnetism and thermal stability of the nanoribbons. The pure TPNR displayed an edge magnetic state, but it disappeared in the edge reconstructed TPNR due to the self-passivation. In addition, we found that the bare TPNR was mechanically unstable because an imaginary vibration mode was obtained. However, the imaginary vibration mode disappeared in the edge passivated TPNRs. No edge magnetism was observed in hydrogen and fluorine passivated TPRNs. In contrast, the oxygen passivated TPNR was more stable than the pure TPNR and the edge-to-edge antiferromagntic (AFM) ground state was obtained. We found that the magnetic ground state could be tuned by the electric field from antiferromagnetic (AFM) to ferromagnetic (FM) ground state. Interestingly, the oxygen passivated TPNR displayed a half-metallic state at a proper electric field in both FM and AFM states. This finding may provoke an intriguing issue for potential spintronics application using the phosphorene nanoribbons. PMID:27189417

  1. Phonon thermal transport through tilt grain boundaries in strontium titanate

    International Nuclear Information System (INIS)

    Zheng, Zexi; Chen, Xiang; Yang, Shengfeng; Xiong, Liming; Chen, Youping; Deng, Bowen; Chernatynskiy, Aleksandr

    2014-01-01

    In this work, we perform nonequilibrium molecular dynamics simulations to study phonon scattering at two tilt grain boundaries (GBs) in SrTiO 3 . Mode-wise energy transmission coefficients are obtained based on phonon wave-packet dynamics simulations. The Kapitza conductance is then quantified using a lattice dynamics approach. The obtained results of the Kapitza conductance of both GBs compare well with those obtained by the direct method, except for the temperature dependence. Contrary to common belief, the results of this work show that the optical modes in SrTiO 3 contribute significantly to phonon thermal transport, accounting for over 50% of the Kapitza conductance. To understand the effect of the GB structural disorder on phonon transport, we compare the local phonon density of states of the atoms in the GB region with that in the single crystalline grain region. Our results show that the excess vibrational modes introduced by the structural disorder do not have a significant effect on phonon scattering at the GBs, but the absence of certain modes in the GB region appears to be responsible for phonon reflections at GBs. This work has also demonstrated phonon mode conversion and simultaneous generation of new modes. Some of the new modes have the same frequency as the initial wave packet, while some have the same wave vector but lower frequencies

  2. Cyclonic circulation of Saturn's atmosphere due to tilted convection

    Science.gov (United States)

    Afanasyev, Y. D.; Zhang, Y.

    2018-02-01

    Saturn displays cyclonic vortices at its poles and the general atmospheric circulation at other latitudes is dominated by embedded zonal jets that display cyclonic circulation. The abundance of small-scale convective storms suggests that convection plays a role in producing and maintaining Saturn's atmospheric circulation. However, the dynamical influence of small-scale convection on Saturn's general circulation is not well understood. Here we present laboratory analogue experiments and propose that Saturn's cyclonic circulation can be explained by tilted convection in which buoyancy forces do not align with the planet's rotation axis. In our experiments—conducted with a cylindrical water tank that is heated at the bottom, cooled at the top and spun on a rotating table—warm rising plumes and cold sinking water generate small anticyclonic and cyclonic vortices that are qualitatively similar to Saturn's convective storms. Numerical simulations complement the experiments and show that this small-scale convection leads to large-scale cyclonic flow at the surface and anticyclonic circulation at the base of the fluid layer, with a polar vortex forming from the merging of smaller cyclonic storms that are driven polewards.

  3. Tilt-table test: its role in modern practice.

    Science.gov (United States)

    Sandhu, Kulwinder S; Khan, Pervez; Panting, John; Nadar, Sunil

    2013-06-01

    Syncope is a major healthcare problem with significant morbidity, mortality and healthcare cost. It is a common symptom with a complex pathophysiology and, therefore, several aetiologies. Tilt-table testing (TTT) is an important, yet perhaps not widely-used, test that forms part of the management of syncope. We sought to assess the utilisation of this test in our institution for the investigation of patients with syncope, to study the referral patterns and the outcomes and usefulness of the TTT in a real-life setting. We undertook a retrospective study of all the TTT that were performed in our institution between January 2009 and October 2009. Of the 69 patients in which TTT was performed, 14 (20%) presented with presyncope, 24 (35%) with a single episode of syncope and 24 (44%) with multiple episodes. The average age was 57.2 years and 64% were female. Of the total patients, 35 (51%) had an abnormal TTT. Of the patients with normal TTT, four had internal loop recorders and six were referred to other medical specialities. The remaining patients (49%) had no formal diagnosis and were referred back to their general practitioner. TTT remains a common test modality and has great value when undertaken in the correct clinical context. This underlines the importance of a detailed clinical history. The European Society of Cardiology guidelines ensure a methodical and rational approach to syncopal patients and aide in choosing the right patient for the right test.

  4. Systematic biases in human heading estimation.

    Directory of Open Access Journals (Sweden)

    Luigi F Cuturi

    Full Text Available Heading estimation is vital to everyday navigation and locomotion. Despite extensive behavioral and physiological research on both visual and vestibular heading estimation over more than two decades, the accuracy of heading estimation has not yet been systematically evaluated. Therefore human visual and vestibular heading estimation was assessed in the horizontal plane using a motion platform and stereo visual display. Heading angle was overestimated during forward movements and underestimated during backward movements in response to both visual and vestibular stimuli, indicating an overall multimodal bias toward lateral directions. Lateral biases are consistent with the overrepresentation of lateral preferred directions observed in neural populations that carry visual and vestibular heading information, including MSTd and otolith afferent populations. Due to this overrepresentation, population vector decoding yields patterns of bias remarkably similar to those observed behaviorally. Lateral biases are inconsistent with standard bayesian accounts which predict that estimates should be biased toward the most common straight forward heading direction. Nevertheless, lateral biases may be functionally relevant. They effectively constitute a perceptual scale expansion around straight ahead which could allow for more precise estimation and provide a high gain feedback signal to facilitate maintenance of straight-forward heading during everyday navigation and locomotion.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-01

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

  6. Analysis of fixed tilt and sun tracking photovoltaic–micro wind based hybrid power systems

    International Nuclear Information System (INIS)

    Sinha, Sunanda; Chandel, S.S.

    2016-01-01

    Graphical abstract: 6 kW p photovoltaic–micro wind based hybrid power system analysis in a Indian Western Himalayan location. - Highlights: • Power generation by a roof mounted photovoltaic–micro wind hybrid system is explored. • Optimum hybrid configurations using fixed and sun tracking photovoltaic systems are determined. • Analysis of hybrid systems with optimally tilted and different sun tracking systems is presented. • Two axis sun tracking systems are found to generate 4.88–26.29% more energy than fixed tilt system. • Hybrid system installed at optimum tilt angle is found to be cost effective than a sun tracking system. - Abstract: In this study fixed tilt and sun tracking photovoltaic based micro wind hybrid power systems are analyzed along with determining the optimum configurations for a 6 kW p roof mounted micro wind based hybrid system using fixed and tracking photovoltaic systems to enhance the power generation potential in a low windy Indian hilly terrain with good solar resource. The main objective of the study is to enhance power generation by focusing on photovoltaic component of the hybrid system. A comparative power generation analysis of different configurations of hybrid systems with fixed tilt, monthly optimum tilt, yearly optimum tilt and 6 different sun tracking photovoltaic systems is carried out using Hybrid Optimization Model for Electric Renewables. Monthly and seasonal optimum tilt angles determined for the location vary between 0° and 60° with annual optimum tilt angle as 29.25°. The optimum configurations for all sun tracking systems except for the two axis tracking system is found to be 7 kW p photovoltaic system, one 5 kW p wind turbine, 10 batteries and a 2 kW p inverter. The optimum configuration for two axis tracking system and two types of fixed tilt systems, is found to be a 8 kW p photovoltaic system, one 5 kW p wind turbine, 10 batteries and a 2 kW p inverter. The results show that horizontal axis with

  7. 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)

  8. 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

  9. Trunnion-Head Stresses in THA: Are Big Heads Trouble?

    Science.gov (United States)

    Lavernia, Carlos J; Iacobelli, David A; Villa, Jesus M; Jones, Kinzy; Gonzalez, Jose L; Jones, William Kinzy

    2015-06-01

    The effects of large heads on stresses at the THA trunnion-head junction and their impact on tribocorrosion/metal ion release remain controversial. A 12/14 3D-model of a stem with different head sizes was investigated. Material properties of titanium were assigned to the trunnion and cobalt-chrome/alumina to the heads. A load simulating walking single-leg stand phase was applied to the head. A total contact head-trunnion interface was assumed. The area underneath the junction underwent significant elevations in stresses as head size increased from 28- to 40-mm. Maximum principal stress doubled between 28 and 40-mm heads, regardless of head material. Stress levels had a direct correlation to head diameter. Stress increases observed using increasingly larger heads will probably contribute to head-trunnion tribocorrosion and ion release. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Head and Neck Cancer Treatment

    Science.gov (United States)

    ... News Physician Resources Professions Site Index A-Z Head and Neck Cancer Treatment Head and neck cancer ... there any new developments in treating my disease? Head and neck cancer overview The way a particular ...

  11. American Head and Neck Society

    Science.gov (United States)

    American Head & Neck Society Mission Statement: Advance Education, Research, and Quality of Care for the head and neck oncology patient. American Head & Neck Society | AHNS The mission of the AHNS is to ...

  12. Magnetic Resonance Imaging (MRI) -- Head

    Medline Plus

    Full Text Available ... MRI of the Head? What is MRI of the Head? Magnetic resonance imaging (MRI) is a noninvasive ... of page What are some common uses of the procedure? MR imaging of the head is performed ...

  13. Effects of trunk-to-head rotation on the labyrinthine responses of rat reticular neurons.

    Science.gov (United States)

    Barresi, M; Grasso, C; Bruschini, L; Berrettini, S; Manzoni, D

    2012-11-08

    Vestibulospinal reflexes elicited by head displacement become appropriate for body stabilization owing to the integration of neck input by the cerebellar anterior vermis. Due to this integration, the preferred direction of spinal motoneurons' responses to animal tilt rotates by the same angle and by the same direction as the head over the body, which makes it dependent on the direction of body displacement rather than on head displacement. It is known that the cerebellar control of spinal motoneurons involves the reticular formation. Since the preferred directions of corticocerebellar units' responses to animal tilt are tuned by neck rotation, as occuring in spinal motoneurons, we investigated whether a similar tuning can be observed also in the intermediate station of reticular formation. In anaesthetized rats, the activity of neurons in the medullary reticular formation was recorded during wobble of the whole animal at 0.156 Hz, a stimulus that tilted the animal's head by a constant amplitude (5°), in a direction rotating clockwise or counter clockwise over the horizontal plane. The response gain and the direction of tilt eliciting the maximal activity were evaluated with the head and body axes aligned and during a maintained body-to-head displacement of 5-20° over the horizontal plane, in either direction. We found that the neck displacement modified the response gain and/or the average activity of most of the responsive neurons. Rotation of the response direction was observed only in a minor percentage of the recorded neurons. The modifications of reticular neurons' responses were different from those observed in the P-cells of the cerebellar anterior vermis, which rarely showed gain and activity changes and often exhibited a rotation of their response directions. In conclusion, reticular neurons take part in the neck tuning of vestibulospinal reflexes by transforming a head-driven sensory input into a body-centred postural response. The present findings

  14. Head injuries in sport.

    Science.gov (United States)

    Cantu, R C

    1996-12-01

    Injuries to the head and neck are the most frequent catastrophic sports injury, and head injuries are the most common direct athletic cause of death. Although direct compressive forces may injure the brain, neural tissue is particularly susceptible to injury from shearing stresses, which are most likely to occur when rotational forces are applied to the head. The most common athletic head injury is concussion, which may very widely in severity. Intracranial haemorrhage is the leading cause of head injury death in sports, making rapid initial assessment and appropriate follow up mandatory after a head injury. Diffuse cerebral swelling is another serious condition that may be found in the child or adolescent athlete, and the second impact syndrome is a major concern in adult athletes. Many head injuries in athletes are the result of improper playing techniques and can be reduced by teaching proper skills and enforcing safety promoting rules. Improved conditioning (particularly of the neck), protective headgear, and careful medical supervision of athletes will also minimise this type of injury.

  15. DYNAMIC ANALYSIS OF HYDRAULIC DRIVE OF TILTING PLATFORM MECHANISM OF DUMP TRUCK

    Directory of Open Access Journals (Sweden)

    P. Kishkevich

    2011-01-01

    Full Text Available Object of research – hydraulic drive of tilting platform mechanism of dump truck. We pro-pose a dynamic model of the hydraulic system. The model takes into account the cyclic operation (lifting, lowering the platform.

  16. DYNAMIC ANALYSIS OF HYDRAULIC DRIVE OF TILTING PLATFORM MECHANISM OF DUMP TRUCK

    OpenAIRE

    P. Kishkevich; A. Safonau; I. Selivonchik; P. Bartosh

    2011-01-01

    Object of research – hydraulic drive of tilting platform mechanism of dump truck. We pro-pose a dynamic model of the hydraulic system. The model takes into account the cyclic operation (lifting, lowering the platform).

  17. Experimental study on the effect of heat flux tilt on rod bundle dryout limitation

    International Nuclear Information System (INIS)

    Sugawara, S.; Terunuma, K.; Kamoshida, H.

    1995-01-01

    The effect of heat flux tilt on rod bundle dryout limitation was studied experimentally using a full-scale mock-up test facility and simulated 36-rod fuel bundles in which heater pins have azimuthal nonuniform heat flux distribution (i.e., heat flux tilt). Experimental results for typical lateral power distribution in the bundle indicate that the bundle dryout power with azimuthal heat flux tilt is higher than that without azimuthal heat flux tilt in the entire experimental range. Consequently, it is concluded that the dryout experiment using the test bundle with heater pins which has circumferentially uniform heat flux distribution gives conservative results for the usual lateral power distribution in a bundle in which the relative power of outermost-circle fuel rods is higher than those of middle- and inner-circle ones. (author). 15 refs., 2 tabs., 8 figs

  18. 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.

  19. Thermal insensitive optical liquid level sensor based on excessively tilted fibre Bragg grating

    OpenAIRE

    Mou, Chengbo; Zhou, Kaiming; Zhang, Lin; Bennion, Ian

    2008-01-01

    We demonstrate a liquid level sensor based on the surrounding medium refractive index (SRI) sensing using of an excessively tilted fibre Bragg grating (ETFBG). The sensor has low thermal cross sensitivity and high SRI responsivity.

  20. Tilt aftereffects in a self-organizing model of the primary visual cortex.

    Science.gov (United States)

    Bednar, J A; Miikkulainen, R

    2000-07-01

    RF-LISSOM, a self-organizing model of laterally connected orientation maps in the primary visual cortex, was used to study the psychological phenomenon known as the tilt aftereffect. The same self-organizing processes that are responsible for the long-term development of the map are shown to result in tilt aftereffects over short timescales in the adult. The model permits simultaneous observation of large numbers of neurons and connections, making it possible to relate high-level phenomena to low-level events, which is difficult to do experimentally. The results give detailed computational support for the long-standing conjecture that the direct tilt aftereffect arises from adaptive lateral interactions between feature detectors. They also make a new prediction that the indirect effect results from the normalization of synaptic efficacies during this process. The model thus provides a unified computational explanation of self-organization and both the direct and indirect tilt aftereffect in the primary visual cortex.

  1. Experimental confirmation of the atomic force microscope cantilever stiffness tilt correction

    Science.gov (United States)

    Gates, Richard S.

    2017-12-01

    The tilt angle (angle of repose) of an AFM cantilever relative to the surface it is interrogating affects the effective stiffness of the cantilever as it analyzes the surface. For typical AFMs and cantilevers that incline from 10° to 15° tilt, this is thought to be a 3%-7% stiffness increase correction. While the theoretical geometric analysis of this effect may have reached a consensus that it varies with cos-2 θ, there is very little experimental evidence to confirm this using AFM cantilevers. Recently, the laser Doppler vibrometry thermal calibration method utilized at NIST has demonstrated sufficient stiffness calibration accuracy, and precision to allow a definitive experimental confirmation of the particular trigonometric form of this tilt effect using a commercial microfabricated AFM cantilever specially modified to allow strongly tilted (up to 15°) effective cantilever stiffness measurements.

  2. 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...

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

    DEFF Research Database (Denmark)

    Heinrichson, Niels; Santos, Ilmar

    2008-01-01

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

  4. 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.

  5. Tilted plane Feldkamp type reconstruction algorithm for spiral cone beam CT

    International Nuclear Information System (INIS)

    Yan Ming; Zhang Cishen

    2005-01-01

    An approximate image reconstruction method for spiral cone beam computed tomography (CT), called tilted plane Feldkamp type reconstruction algorithm (TPFR), is presented in this paper, which extends Feldkamp cone beam reconstruction algorithm to deal with its inaccuracy and artifact problems caused by large cone angle. This is done by tilting the reconstructing planes to minimize the cone angle and optimally fit the spiral segment of the source. The tilted plane image reconstruction requires reforming the three-dimensional projection data set for the tilted plane and application of Feldkamp algorithm to the reformed data set. Analytical and computational results can show that the image reconstruction performance of the proposed TPFR algorithm is superior to that of the Feldkamp reconstruction algorithm in the image quality, volume coverage speed, maximum achievable pitch value, and slice sensitivity profiles. Moreover, it provides more accurate image reconstruction than the existing two-dimensional reconstruction algorithms

  6. Optimization of tilt angle for solar panel: Case study for Madinah, Saudi Arabia

    International Nuclear Information System (INIS)

    Benghanem, M.

    2011-01-01

    This article analyzes the optimal choice of the tilt angle for the solar panel in order to collect the maximum solar irradiation. In this paper, the collector surface is assumed to be facing toward equator. The study is based upon the measured values of daily global and diffuse solar radiation on a horizontal surface. It is shown that the optimal angle of tilt (β opt ) for each month, allows us to collected the maximum solar energy for Madinah site. Annual optimum tilt angle is found to be approximately equal to latitude of the location. It is found that the loss in the amount of collected energy when using the yearly average fixed angle is around 8% compared with the monthly optimum tilt β opt .

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

    International Nuclear Information System (INIS)

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

    2007-01-01

    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

  8. Head-to-Head Comparison of Serum Fractionation Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Whiteaker, Jeffrey R.; Zhang, Heidi; Eng, Jimmy K.; Fang, Ruihua; Piening, Brian D.; Feng, Li-Chia; lorentzen, Travis D.; Schoenherr, Regine M.; Keane, John F.; Holzman, Ted; Fitzgibbon, Matthew; Lin, Chen Wei; Zhang, Hui; Cooke, Kelly; Liu, Tao; Camp, David G.; Anderson, Leigh N.; Watts, Julian; Smith, Richard D.; McIntosh, Martin; Paulovich, Amanda G.

    2007-02-01

    Multiple approaches for simplifying the serum proteome have been described. These techniques are generally developed across different laboratories, samples, mass spectrometry platforms, and analysis tools. Hence, comparing the available schemes is impossible from the existing literature because of confounding variables. We describe a head-to-head comparison of several serum fractionation schemes, including N-linked glycopeptide enrichment, cysteinyl-peptide enrichment, magnetic bead separation (C3, C8, and WCX), size fractionation, Protein A/G depletion, and immunoaffinity column depletion of abundant serum proteins. Each technique was compared to results obtained from unfractionated human serum. The results show immunoaffinity subtraction is the most effective means for simplifying the serum proteome and maintaining reasonable sample throughput. The reported dataset is publicly available and provides a standard against which emergent technologies can be compared and evaluated for their contribution to serum-based biomarker discovery.

  9. CT heads diagnosing chest pathology? Whatever next?

    Energy Technology Data Exchange (ETDEWEB)

    Holdsworth, Gary, E-mail: gary.holdsworth@midyorks.nhs.uk [Radiology Department, Midyorks Hospitals NHS Trust, Pinderfields General Hospital Aberford Road Wakefield, West Yorkshire, WF1 4DG (United Kingdom); Clarke, Ruth, E-mail: ruth.clarke@midyorks.nhs.uk [Radiology Department, Midyorks Hospitals NHS Trust, Pinderfields General Hospital Aberford Road Wakefield, West Yorkshire, WF1 4DG (United Kingdom)

    2011-11-15

    This case report presents two cases where subcutaneous emphysema visualised on computerised tomography examinations of the head subsequently led to the diagnoses of pathology within the thorax. The pathophysiology of traumatic subcutaneous emphysema within the head and neck is briefly discussed, along with examples of other causes of this condition within this anatomical region. The primary aim of this report is to draw attention to the necessity for a thorough review of any CT head examination, including both intra- and extra-cranial structures, undertaken at a variety of window settings.

  10. Femoral head avascular necrosis

    International Nuclear Information System (INIS)

    Chrysikopoulos, H.; Sartoris, D.J.; Resnick, D.L.; Ashburn, W.; Pretorius, T.

    1988-01-01

    MR imaging has been shown to be more sensitive and specific than planar scintigraphy for avascular necrosis (AVN) of the femoral head. However, experience with single photon emission CT (SPECT) is limited. The authors retrospectively compared 1.5-T MR imaging with SPECT in 14 patients with suspected femoral head AVN. Agreement between MR imaging and SPECT was present in 24 femurs, 14 normal and ten with AVN. MR imaging showed changes of AVN in the remaining four femoral heads. Of these, one was normal and the other three inconclusive for AVN by SPECT. The authors conclude that MR imaging is superior to SPECT for the evaluation of AVN of the hip

  11. Integrated polymer polarization rotator based on tilted laser ablation

    Science.gov (United States)

    Poulopoulos, Giannis; Kalavrouziotis, Dimitrios; Missinne, Jeroen; Bosman, Erwin; Van Steenberge, Geert; Apostolopoulos, Dimitrios; Avramopoulos, Hercules

    2017-02-01

    sidewalls, employing the tilted laser ablation technology, currently available at CMST. Therefore, the aforementioned simulation steps adhere fully to the respective design rules, taking into account the anticipated fabrication variations

  12. 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.

  13. SU-E-T-589: Optimization of Patient Head Angle Position to Spare Hippocampus During the Brain Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Cheon, G; Kang, Y [Radiation Oncology, Seoul St. Mary’s Hospital, Seoul (Korea, Republic of); Kang, S; Kim, T; Kim, D; Suh, T [The Catholic University of Korea, Seoul (Korea, Republic of)

    2015-06-15

    Purpose: Hippocampus is one of the important organs which controls emotions, behaviors, movements the memorizing and learning ability. In the conventional head & neck therapy position, it is difficult to perform the hippocampal-sparing brain radiation therapy. The purpose of this study is to investigate optimal head angle which can save the hippocampal-sparing and organ at risk (OAR) in conformal radiation therapy (CRT), Intensity modulation radiation therapy (IMRT) and helical tomotherapy (HT). Methods: Three types of radiation treatment plans, CRT, IMRT and Tomotherapy plans, were performed for 10 brain tumor patients. The image fusion between CT and MRI data were used in the contour due to the limited delineation of the target and OAR in the CT scan. The optimal condition plan was determined by comparing the dosimetric performance of the each plan with the use of various parameters which include three different techniques (CRT, IMRT, HT) and 4 angle (0, 15, 30, 40 degree). The each treatment plans of three different techniques were compared with the following parameters: conformity index (CI), homogeneity index (HI), target coverage, dose in the OARs, monitor units (MU), beam on time and the normal tissue complication probability (NTCP). Results: HI, CI and target coverage was most excellent in head angle 30 degree among all angle. When compared by modality, target coverage and CI showed good results in IMRT and TOMO than compared to the CRT. HI at the head angle 0 degrees is 1.137±0.17 (CRT), 1.085±0.09 (IMRT) and 1.077±0.06 (HT). HI at the head angle 30 degrees is 1.056±0.08 (CRT), 1.020±0.05 (IMRT) and 1.022±0.07 (HT). Conclusion: The results of our study show that when head angle tilted at 30 degree, target coverage, HI, CI were improved, and the dose delivered to OAR was reduced compared with conventional supine position in brain radiation therapy. This work was supported by the Radiation Technology R&D program (No. 2013M2A2A7043498) and the Mid

  14. SU-E-T-589: Optimization of Patient Head Angle Position to Spare Hippocampus During the Brain Radiation Therapy

    International Nuclear Information System (INIS)

    Cheon, G; Kang, Y; Kang, S; Kim, T; Kim, D; Suh, T

    2015-01-01

    Purpose: Hippocampus is one of the important organs which controls emotions, behaviors, movements the memorizing and learning ability. In the conventional head & neck therapy position, it is difficult to perform the hippocampal-sparing brain radiation therapy. The purpose of this study is to investigate optimal head angle which can save the hippocampal-sparing and organ at risk (OAR) in conformal radiation therapy (CRT), Intensity modulation radiation therapy (IMRT) and helical tomotherapy (HT). Methods: Three types of radiation treatment plans, CRT, IMRT and Tomotherapy plans, were performed for 10 brain tumor patients. The image fusion between CT and MRI data were used in the contour due to the limited delineation of the target and OAR in the CT scan. The optimal condition plan was determined by comparing the dosimetric performance of the each plan with the use of various parameters which include three different techniques (CRT, IMRT, HT) and 4 angle (0, 15, 30, 40 degree). The each treatment plans of three different techniques were compared with the following parameters: conformity index (CI), homogeneity index (HI), target coverage, dose in the OARs, monitor units (MU), beam on time and the normal tissue complication probability (NTCP). Results: HI, CI and target coverage was most excellent in head angle 30 degree among all angle. When compared by modality, target coverage and CI showed good results in IMRT and TOMO than compared to the CRT. HI at the head angle 0 degrees is 1.137±0.17 (CRT), 1.085±0.09 (IMRT) and 1.077±0.06 (HT). HI at the head angle 30 degrees is 1.056±0.08 (CRT), 1.020±0.05 (IMRT) and 1.022±0.07 (HT). Conclusion: The results of our study show that when head angle tilted at 30 degree, target coverage, HI, CI were improved, and the dose delivered to OAR was reduced compared with conventional supine position in brain radiation therapy. This work was supported by the Radiation Technology R&D program (No. 2013M2A2A7043498) and the Mid

  15. Component level study of an actively lubricated LEG Tilting Pad Bearing: Theory and experiment

    DEFF Research Database (Denmark)

    Cerda Varela, Alejandro Javier; Santos, Ilmar Ferreira

    2018-01-01

    This article constitutes the second step in a research effort aiming at evaluating the feasibility of introducing active characteristics into standard leading edge groove (LEG) tilting pad journal bearings. The strategy proposed is to control the LEG inlet flow using a servovalve. This work...... bearing design, validate the available simulation tool and exemplify on a conceptual level the operational benefits from introducing this technology into standard LEG Tilting Pad Bearings....

  16. Tilt stability in nonlinear programming under Mangasarian-Fromovitz constraint qualification

    Czech Academy of Sciences Publication Activity Database

    Mordukhovich, B. S.; Outrata, Jiří

    2013-01-01

    Roč. 49, č. 3 (2013), s. 446-464 ISSN 0023-5954 R&D Projects: GA ČR(CZ) GAP201/12/0671 Institutional support: RVO:67985556 Keywords : variational analysis * second-order theory * generalized differentiation * tilt stability Subject RIV: BA - General Mathematics Impact factor: 0.563, year: 2013 http://library.utia.cas.cz/separaty/2013/MTR/outrata-tilt stability in nonlinear programming under mangasarian-fromovitz constraint qualification.pdf

  17. 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.

  18. 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

  19. Solar Cycle Variability Induced by Tilt Angle Scatter in a Babcock-Leighton Solar Dynamo Model

    Science.gov (United States)

    Karak, Bidya Binay; Miesch, Mark

    2017-09-01

    We present results from a three-dimensional Babcock-Leighton (BL) dynamo model that is sustained by the emergence and dispersal of bipolar magnetic regions (BMRs). On average, each BMR has a systematic tilt given by Joy’s law. Randomness and nonlinearity in the BMR emergence of our model produce variable magnetic cycles. However, when we allow for a random scatter in the tilt angle to mimic the observed departures from Joy’s law, we find more variability in the magnetic cycles. We find that the observed standard deviation in Joy’s law of {σ }δ =15^\\circ produces a variability comparable to the observed solar cycle variability of ˜32%, as quantified by the sunspot number maxima between 1755 and 2008. We also find that tilt angle scatter can promote grand minima and grand maxima. The time spent in grand minima for {σ }δ =15^\\circ is somewhat less than that inferred for the Sun from cosmogenic isotopes (about 9% compared to 17%). However, when we double the tilt scatter to {σ }δ =30^\\circ , the simulation statistics are comparable to the Sun (˜18% of the time in grand minima and ˜10% in grand maxima). Though the BL mechanism is the only source of poloidal field, we find that our simulations always maintain magnetic cycles even at large fluctuations in the tilt angle. We also demonstrate that tilt quenching is a viable and efficient mechanism for dynamo saturation; a suppression of the tilt by only 1°-2° is sufficient to limit the dynamo growth. Thus, any potential observational signatures of tilt quenching in the Sun may be subtle.

  20. Effect of manual tilt adjustments on incident irradiance on fixed and tracking solar panels

    International Nuclear Information System (INIS)

    Lubitz, William David

    2011-01-01

    Hourly typical meteorological year (TMY3) data was utilized with the Perez radiation model to simulate solar radiation on fixed, azimuth tracking and two axis tracking surfaces at 217 geographically diverse temperate latitude sites across the contiguous United States of America. The optimum tilt angle for maximizing annual irradiation on a fixed south-facing panel varied from being equal to the latitude at low-latitude, high clearness sites, to up to 14 o less than the latitude at a north-western coastal site with very low clearness index. Across the United States, the optimum tilt angle for an azimuth tracking panel was found to be on average 19 o closer to vertical than the optimum tilt angle for a fixed, south-facing panel at the same site. Azimuth tracking increased annual solar irradiation incident on a surface by an average of 29% relative to a fixed south-facing surface at optimum tilt angle. Two axis tracking resulted in an average irradiation increase of 34% relative to the fixed surface. Introduction of manual surface tilt changes during the year produced a greater impact for non-tracking surfaces than it did for azimuth tracking surfaces. Even monthly tilt changes only resulted in an average annual irradiation increase of 5% for fixed panels and 1% for azimuth tracked surfaces, relative to using a single optimized tilt angle in each case. In practice, the decision whether to manually tilt panels requires balancing the added cost in labor and the panel support versus the extra energy generation and the cost value of that energy. A spreadsheet file is available that gives individual results for each of the 217 simulated sites.

  1. Long-wavelength tilting of the Australian continent since the Late Cretaceous

    OpenAIRE

    DiCaprio, Lydia; Gurnis, Michael; Müller, R. Dietmar

    2009-01-01

    Global sea level and the pattern of marine inundation on the Australian continent are inconsistent. We quantify this inconsistency and show that it is partly due to a long wavelength, anomalous, downward tilting of the continent to the northeast by 300 m since the Eocene. This downward tilting occurred as Australia approached the subduction systems in South East Asia and is recorded by the progressive inundation of the northern margin of Australia. From the Oligocene to the Pliocene, the long...

  2. 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.

  3. Obtaining Volar Tilt in Distal Radius Fixation: Use of a Screw as a Proximal Post.

    Science.gov (United States)

    Watson, B Collier; Taylor, Benjamin C; Madsen, Adam; Persinger, Freddie D; Malarkey, Andy R

    2016-01-01

    Volar plating of distal radius fractures was introduced as a means to circumvent some of the issues with dorsal-based plating but has been shown not to be a complete panacea, as other advantages and challenges have subsequently been discovered. Careful attention and proper technique must be utilized to restore and maintain volar tilt. This study reports a technique of using a locking screw as a proximal peg to reliably obtain the volar tilt in a simple fashion.

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

    DEFF Research Database (Denmark)

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

    2005-01-01

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

  5. Constriction of collateral arteries induced by "head-up tilt" in patients with occlusive arterial disease of the legs

    DEFF Research Database (Denmark)

    Agerskov, K; Henriksen, O; Tønnesen, K H

    1981-01-01

    not change the pressure gradient from femoral to popliteal artery in the patients with occlusion of the superficial femoral artery, indicating that the flow resistance offered by the collateral arteries had increased. In a bilateral sympathectomised patient the increase in collateral resistance was almost...... absent indicating that the constriction of the collateral arteries is mainly mediated via sympathetic vasoconstrictor fibres....

  6. 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

    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 are s...

  7. Probing the mechanism of saccade-associated head movements through observations of head movement propensity and cognition in the elderly.

    Science.gov (United States)

    Thumser, Zachary C; Adams, Nancy L; Lerner, Alan J; Stahl, John S

    2010-05-01

    Humans may accomplish gaze shifts by eye-only saccades or combined eye-head saccades. The mechanisms that determine whether the head moves remain poorly understood. Many observations can be explained if phylogenetically ancient circuits generate eye-head saccades by default and frontal cerebral structures interrupt this synergy when eye-only saccades are preferable. Saccade-associated head movements have been reported to increase in the elderly. To test the hypothesis of frontal inhibition of head movements, we investigated whether the increase is associated with a decline in frontal cognitive function. We measured head movement tendencies and cognition in volunteers aged 61-80. Measures of head movement tendency included the customary range of eye eccentricity, customary range of head eccentricity, range of target eccentricities evoking predominantly eye-only saccades, and two measures of head amplitude variation as a function of target eccentricity. Cognitive measures encompassed verbal fluency, verbal memory, non-verbal memory, and executive function. There was no correlation between cognition and any measure of head movement tendency. We combined these elderly data with measurements of head movements in a group aged 21-67 and found mildly reduced, not increased, head movement tendencies with age. However, when confronted with a task that could be accomplished without moving the head, young subjects were more likely to cease all head movements. While inconclusive regarding the hypothesis of inhibition of saccade-associated head movements by cerebral structures, the results indicate the need to distinguish between mechanisms that define head movement tendencies and mechanisms that adapt head motion to the geometry of a specific task.

  8. Head midline position for preventing the occurrence or extension of germinal matrix-intraventricular hemorrhage in preterm infants.

    Science.gov (United States)

    Romantsik, Olga; Calevo, Maria Grazia; Bruschettini, Matteo

    2017-07-20

    position, or undertaking a strategy of regular position change, or having no prespecified position. We included trials enrolling infants with existing GM-IVH and planned to assess extension of hemorrhage in a subgroup of infants. We planned to analyze horizontal (flat) versus head elevated positions separately for all body positions. We used standard methods of the Cochrane Neonatal Review Group. For each of the included trials, two review authors independently extracted data (e.g., number of participants, birth weight, gestational age, initiation and duration of head midline position, co-intervention with horizontal vs head elevated position, use of physical aids to maintain head position) and assessed risk of bias (e.g., adequacy of randomization, blinding, completeness of follow-up). The primary outcomes considered in this review are GM-IVH , severe IVH, and neonatal death. Our search strategy yielded 2696 references. Two review authors independently assessed all references for inclusion. Two randomized controlled trials, for a total of 110 infants, met the inclusion criteria of this review. Both trials compared supine midline head position with the bed at 0° versus supine head rotated 90° with the bed at 0°. We found no trials that compared supine versus prone midline head position, and no trials that compared effects of head tilting. We found no significant differences in rates of GM-IVH (typical risk ratio [RR] 1.14, 95% confidence interval [CI] 0.55 to 2.35; typical risk difference [RD] 0.03, 95% CI -0.13 to 0.18; two studies, 110 infants; I 2 = 0% for RR and I 2 = 0% for RD), severe IVH (typical RR 1.57, 95% CI 0.28 to 8.98; typical RD 0.02, 95% CI -0.06 to 0.10; two studies, 110 infants; I 2 = 0% for RR and I 2 = 0% for RD), and neonatal mortality (typical RR 0.52, 95% CI 0.16 to 1.65; typical RD -0.07, 95% CI -0.18 to 0.05; two studies, 110 infants; I 2 = 28% for RR and I 2 = 44% for RD). Among secondary outcomes, we found no significant differences in terms

  9. Nanoscale Tilt Measurement Using a Cyclic Interferometer with Phase Stepping and Multiple Reflections

    Science.gov (United States)

    Naderishahab, Tahereh

    High accuracy tilt or roll angle measurement is required for a variety of engineering and scientific applications. Optical interferometry is normally used because it is non-contact and can measure tilt with a very high degree of accuracy. In this thesis, a cyclic interferometer has been developed with four mirrors to measure tilt angles as small as a few nanoradians. To measure the phase, a novel and simple method of phase shift by polarization was developed to enhance measurement sensitivity and accuracy. Since the cyclic interferometer is insensitive to external vibrations and turbulences, polarization phase step was accomplished with relative ease. To introduce the phase shift, a quarter wave plate and a half wave plate were used with a polarized laser beam. Multiple reflections were also introduced in the cyclic interferometer to enhance tilt measurement capability. A new method was developed to evaluate phase and eventually measure the tilt even in the case of changing fringe visibility. The results of these studies show that the multiple reflection cyclic interferometer can be used to measure object tilts in the order of 0.2 nanoradians or 10. (-5) arc second.

  10. Uniform tilt-angle micromirror array for multi-object spectroscopy

    Science.gov (United States)

    Waldis, Severin; Clerc, Pierre-Andre; Zamkotsian, Frederic; Zickar, Michael; Noell, Wilfried; de Rooij, Nico

    2007-01-01

    We report on micromirror arrays being developed for the use as reflective slit mask in Multi Object Spectrographs for astronomical applications. The micromirrors are etched in bulk single crystal silicon whereas the cantilever type suspension is realized by surface micromachining. One micromirror element is 100μm x 200μm in size. The micromirrors are actuated electrostatically by electrodes located on a second chip. The use of silicon on insulator (SOI) wafers for both mirror and electrode chip ensures thermal compatibility for cryogenic operation. A system of multiple landing beams has been developed, which passively locks the mirror at a well defined tilt angle when actuated. The mechanical tilt angle obtained is 20 ° at a pull-in voltage of 90V. Measurements with an optical profiler showed that the tilt angle of the actuated and locked mirror is stable with a precision of one arc minute over a range of 15V. This locking system makes the tilt angle merely independent from process variations across the wafer and thus provides uniform tilt angle over the whole array. The precision on tilt angle from mirror to mirror measured is one arc minute. The surface quality of the mirrors in actuated state is better than 10nm peak-to-valley and the local roughness is around 1nm RMS.

  11. 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.

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

    International Nuclear Information System (INIS)

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

    2017-01-01

    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°. (paper)

  13. Computed Tomography (CT) -- Head

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    Full Text Available ... used to detect: bleeding, brain injury and skull fractures in patients with head injuries. bleeding caused by ... be asked to remove hearing aids and removable dental work. Women will be asked to remove bras ...

  14. TCGA head Neck

    Science.gov (United States)

    Investigators with The Cancer Genome Atlas (TCGA) Research Network have discovered genomic differences – with potentially important clinical implications – in head and neck cancers caused by infection with the human papillomavirus (HPV).

  15. Computed Tomography (CT) -- Head

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    Full Text Available ... microphone. top of page How does the procedure work? In many ways CT scanning works very much ... head CT scanning. Manufacturers of intravenous contrast indicate mothers should not breastfeed their babies for 24-48 ...

  16. Head Start Impact Study

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    U.S. Department of Health & Human Services — Nationally representative, longitudinal information from an evaluation where children were randomly assigned to Head Start or community services as usual;direct...

  17. Early Head Start Evaluation

    Data.gov (United States)

    U.S. Department of Health & Human Services — Longitudinal information from an evaluation where children were randomly assigned to Early Head Start or community services as usual;direct assessments and...

  18. Computed Tomography (CT) -- Head

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    Full Text Available ... assess head injuries, severe headaches, dizziness, and other symptoms of aneurysm, bleeding, stroke and brain tumors. It ... within the brain shortly after a patient exhibits symptoms of a stroke. a stroke, especially with a ...

  19. Computed Tomography (CT) -- Head

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    Full Text Available ... Survey Do you have a personal story about radiology? Share your patient story here Images × Image Gallery ... Pregnancy Head and Neck Cancer X-ray, Interventional Radiology and Nuclear Medicine Radiation Safety Images related to ...

  20. Computed Tomography (CT) -- Head

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    Full Text Available ... special x-ray equipment to help assess head injuries, severe headaches, dizziness, and other symptoms of aneurysm, ... cancer. In emergency cases, it can reveal internal injuries and bleeding quickly enough to help save lives. ...

  1. Computed Tomography (CT) -- Head

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    Full Text Available ... rays). top of page What are some common uses of the procedure? CT scanning of the head ... special computer program processes this large volume of data to create two-dimensional cross-sectional images of ...

  2. Computed Tomography (CT) -- Head

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    Full Text Available ... scans in children should always be done with low-dose technique. top of page What are the ... page Additional Information and Resources RTAnswers.org Radiation Therapy for Brain Tumors Radiation Therapy for Head and ...

  3. Overview of Head Injuries

    Science.gov (United States)

    ... kept in the emergency department or hospital for observation. Children who have had a minor head injury ... penetrating trauma (such as a knife or gunshot wound). Injuries may range from relatively small hematomas (collections ...

  4. Computed Tomography (CT) -- Head

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    Full Text Available ... rays). top of page What are some common uses of the procedure? CT scanning of the head ... is done because a potential abnormality needs further evaluation with additional views or a special imaging technique. ...

  5. Computed Tomography (CT) -- Head

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    Full Text Available ... headaches, dizziness, and other symptoms of aneurysm, bleeding, stroke and brain tumors. It also helps your doctor ... scanning provides more detailed information on head injuries, stroke , brain tumors and other brain diseases than regular ...

  6. Femoral head necrosis; Hueftkopfnekrose

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, J.; Scheurecker, G.; Scheurecker, A.; Stoeger, A.; Huber, A. [Roentgeninstitut am Schillerpark, Linz (Austria); Hofmann, S. [Orthopaedisches Landeskrankenhaus Stolzalpe (Austria)

    2009-05-15

    The epidemiology and pathohistogenesis of avascular femoral head necrosis has still not been clarified in detail. Because the course of the disease runs in stages and over a long time period nearly always culminates in the necessity for a total hip prosthesis, an exact radiological evaluation is of paramount importance for the treatment. There is a need for a common staging system to enable comparison of different therapy concepts and especially their long-term results. In this article the ARCO staging system is described in full detail, which includes all radiological modalities as well as histopathological alterations. (orig.) [German] Bei der avaskulaeren Femurkopfnekrose handelt es sich um ein Krankheitsbild, dessen Ursachen noch immer nicht vollstaendig geklaert sind. Da die Erkrankung stadienhaft verlaeuft und ueber einen laengeren Zeitraum betrachtet nahezu immer in einem prothetischen Hueftersatz muendet, ist eine genaue radiologische Abklaerung fuer die Behandlung von enormer Bedeutung. Um Langzeiterfolge verschiedener Therapiekonzepte vergleichen zu koennen, sind eine exakte Beschreibung und darauf basierend die Verwendung einer einheitlichen Stadieneinteilung wuenschenswert. In der vorliegenden Arbeit wird die ARCO-Stadieneinteilung im Detail beschrieben, die alle bildgebenden Methoden beruecksichtigt und histopathologische Veraenderungen mit einbezieht. (orig.)

  7. Update on abusive head trauma.

    Science.gov (United States)

    Shaahinfar, Ashkon; Whitelaw, Kevin D; Mansour, Karim M

    2015-06-01

    This article provides an update on abusive head trauma (AHT), focusing on new developments most salient to the emergency medicine clinician, including epidemiology, clinical recognition, diagnostic work-up, management of neurologic injury, and public health implications. The recent literature has focused on honing the clinician's ability to recognize AHT and its immediate sequelae, to more accurately distinguish between abusive and accidental head injuries by patterns of neuroimaging and retinal hemorrhages, and to appreciate the long-term impacts. Specifically, both a clinical prediction rule and biomarker show promise, and new research advocates for the early identification of subclinical seizures as well as cervical spine injuries. The emergency medicine provider must be able to recognize and manage children who may have AHT and to appreciate when the diagnostic findings warrant consultation with a child protection team. These authors summarize the recent and notable advances in our understanding of AHT.

  8. Head Start Family and Child Experiences Survey (FACES) 2000 Cohort

    Data.gov (United States)

    U.S. Department of Health & Human Services — Descriptive, longitudinal study including direct assessments, classroom observation, parent and teacher interviews, for a nationally represenative sample of Head...

  9. Head Start Family and Child Experiences Survey (FACES) 2006 Cohort

    Data.gov (United States)

    U.S. Department of Health & Human Services — Descriptive, longitudinal study including direct assessments, classroom observation, parent and teacher interviews, for a nationally represenative sample of Head...

  10. Head Start Family and Child Experiences Survey (FACES) 2003 Cohort

    Data.gov (United States)

    U.S. Department of Health & Human Services — Descriptive, longitudinal study including direct assessments, classroom observation, parent and teacher interviews, for a nationally represenative sample of Head...

  11. Head Start Family and Child Experiences Survey (FACES) 1997 Cohort

    Data.gov (United States)

    U.S. Department of Health & Human Services — Descriptive, longitudinal study including direct assessments, classroom observation, parent and teacher interviews, for a nationally represenative sample of Head...

  12. Position, Attitude, and Fault-Tolerant Control of Tilting-Rotor Quadcopter

    Science.gov (United States)

    Kumar, Rumit

    The aim of this thesis is to present algorithms for autonomous control of tilt-rotor quadcopter UAV. In particular, this research work describes position, attitude and fault tolerant control in tilt-rotor quadcopter. Quadcopters are one of the most popular and reliable unmanned aerial systems because of the design simplicity, hovering capabilities and minimal operational cost. Numerous applications for quadcopters have been explored all over the world but very little work has been done to explore design enhancements and address the fault-tolerant capabilities of the quadcopters. The tilting rotor quadcopter is a structural advancement of traditional quadcopter and it provides additional actuated controls as the propeller motors are actuated for tilt which can be utilized to improve efficiency of the aerial vehicle during flight. The tilting rotor quadcopter design is accomplished by using an additional servo motor for each rotor that enables the rotor to tilt about the axis of the quadcopter arm. Tilting rotor quadcopter is a more agile version of conventional quadcopter and it is a fully actuated system. The tilt-rotor quadcopter is capable of following complex trajectories with ease. The control strategy in this work is to use the propeller tilts for position and orientation control during autonomous flight of the quadcopter. In conventional quadcopters, two propellers rotate in clockwise direction and other two propellers rotate in counter clockwise direction to cancel out the effective yawing moment of the system. The variation in rotational speeds of these four propellers is utilized for maneuvering. On the other hand, this work incorporates use of varying propeller rotational speeds along with tilting of the propellers for maneuvering during flight. The rotational motion of propellers work in sync with propeller tilts to control the position and orientation of the UAV during the flight. A PD flight controller is developed to achieve various modes of the

  13. Antipredatory function of head shape for vipers and their mimics.

    Directory of Open Access Journals (Sweden)

    Janne K Valkonen

    Full Text Available Most research into the adaptive significance of warning signals has focused on the colouration and patterns of prey animals. However, behaviour, odour and body shape can also have signal functions and thereby reduce predators' willingness to attack defended prey. European vipers all have a distinctive triangular head shape; and they are all venomous. Several non-venomous snakes, including the subfamily Natricinae, commonly flatten their heads (also known as head triangulation when disturbed. The adaptive significance of this potential behavioural mimicry has never been investigated.We experimentally tested if the triangular head shape typical of vipers offers protection against predation. We compared the predation pressure of free-ranging predators on artificial snakes with triangular-shaped heads against the pressure on replicas with narrow heads. Snakes of both head types had either zigzag patterned bodies, typical of European vipers, or plain (patternless bodies. Plain snakes with narrower Colubrid-like heads suffered significantly higher predation by raptors than snakes with triangular-shaped heads. Head shape did not, however, have an additive effect on survival in zigzag-patterned snakes, suggesting that species which differ from vipers in colouration and pattern would benefit most from behavioural mimicry. Our results demonstrate that the triangular head shape typical of vipers can act as a warning signal to predators. We suggest that head-shape mimicry may be a more common phenomenon among more diverse taxa than is currently recognised.

  14. Femoral head retroposition as a potential compensatory mechanism in patients with a severe mismatch between pelvic incidence and lumbar lordosis.

    Science.gov (United States)

    Cheng, Xiaofei; Zhang, Kai; Sun, Xiaojiang; Zhao, Changqing; Li, Hua; Zhao, Jie

    2017-12-01

    Severe mismatch between pelvic incidence (PI) and lumbar lordosis (LL) leads to extra anterior displacement of the gravity line. The objective of this study is to investigate whether femoral head retroposition is a separate compensatory mechanism responsible for the extra anterior displacement. Based on the values of PI and LL, 94 patients were divided into the PI-LL match group (PI-LL ≤ 0°), the mild PI-LL mismatch group (20°> PI-LL >0°), and the severe PI-LL mismatch group (PI-LL ≥ 20°). A series of parameters including PI, LL, PI-LL, thoracic kyphosis (TK), pelvic tilt (PT), sacral slope (SS), knee flexion angle (KFA), tibial obliquity angle (TOA), sagittal vertical axis (SVA), S1 overhang, femoral head shift (FHS), and pelvic shift (PS) were measured and compared among the three groups. The severe PI-LL mismatch group exhibited significantly greater PI, PI-LL, PT, KFA, SVA, PS, and FHS, and less LL and TK, compared with the control and mild PI-LL mismatch group. The mild PI-LL mismatch group had significantly greater PI-LL, PT, KFA, TOA, and S1 overhang, and less LL and SS than the control group. SS, TOA, and S1 overhang in the severe PI-LL mismatch group differed significantly from that in the control group, but did not differ significantly from that in the mild PI-LL mismatch group. Femoral head retroposition is an entirely separate compensatory mechanism and, in this study, participated in the compensation for the anterior displacement of the gravity line induced by extra-sagittal spinal malalignment in patients with severe PI-LL mismatch.

  15. Octahedral tilt transitions in the relaxor ferroelectric Na1/2Bi1/2TiO3

    International Nuclear Information System (INIS)

    Meyer, Kai-Christian; Gröting, Melanie; Albe, Karsten

    2015-01-01

    The kinetics of octahedral tilt transitions in the lead-free relaxor material sodium bismuth titanate Na 1/2 Bi 1/2 TiO 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. Magnetic Resonance Imaging (MRI) -- Head

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    Full Text Available ... Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) - Head Magnetic resonance imaging (MRI) of the head uses a powerful ... Head? What is MRI of the Head? Magnetic resonance imaging (MRI) is a noninvasive medical test that ...

  17. Magnetic Resonance Imaging (MRI) -- Head

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    Full Text Available ... News Physician Resources Professions Site Index A-Z Magnetic Resonance Imaging (MRI) - Head Magnetic resonance imaging (MRI) of the head ... limitations of MRI of the Head? What is MRI of the Head? Magnetic resonance imaging (MRI) is ...

  18. The structure of strongly tilted current sheets in the Earth magnetotail

    Directory of Open Access Journals (Sweden)

    I. Y. Vasko

    2014-02-01

    Full Text Available We investigate strongly tilted (in the y–z GSM plane current sheets (CSs in the Earth magnetotail using data from the Cluster mission. We analyze 29 CS crossings observed in 2001–2004. The characteristic current density, magnetic field at the CS boundary and the CS thickness of strongly tilted CSs are similar to those reported previously for horizontal (not tilted CSs. We confirm that strongly tilted CSs are generally characterized by a rather large northward component of the magnetic field. The field-aligned current in strongly tilted CSs is on average two times larger than the transverse current. The proton adiabaticity parameter, κp, is larger than 0.5 in 85% of strongly tilted CSs due to the large northward magnetic field. Thus, the proton dynamics is stochastic for 18 current sheets with 0.5 p p > 3, whereas electrons are magnetized for all observed current sheets. Strongly tilted CSs provide a unique opportunity to measure the electric field component perpendicular to the CS plane. We find that most of the electric field perpendicular to the CS plane is due to the decoupling of electron and ion motions (plasma polarization. For 27 CSs we determine profiles of the electrostatic potential, which is due to the plasma polarization. Drops in the potential between the neutral plane and the CS boundary are within the range of 200 V to 12 kV, while maximal values of the electric field are within the range of 0.2 mV m−1 to 8 mV m−1. For 16 CSs the observed potentials are in accordance with Ohm's law, if the electron current density is assumed to be comparable to the total current density. In 15 of these CSs the profile of the polarization potential is approximately symmetric with respect to the neutral plane and has minimum therein.

  19. Estimating 3D tilt from local image cues in natural scenes

    Science.gov (United States)

    Burge, Johannes; McCann, Brian C.; Geisler, Wilson S.

    2016-01-01

    Estimating three-dimensional (3D) surface orientation (slant and tilt) is an important first step toward estimating 3D shape. Here, we examine how three local image cues from the same location (disparity gradient, luminance gradient, and dominant texture orientation) should be combined to estimate 3D tilt in natural scenes. We collected a database of natural stereoscopic images with precisely co-registered range images that provide the ground-truth distance at each pixel location. We then analyzed the relationship between ground-truth tilt and image cue values. Our analysis is free of assumptions about the joint probability distributions and yields the Bayes optimal estimates of tilt, given the cue values. Rich results emerge: (a) typical tilt estimates are only moderately accurate and strongly influenced by the cardinal bias in the prior probability distribution; (b) when cue values are similar, or when slant is greater than 40°, estimates are substantially more accurate; (c) when luminance and texture cues agree, they often veto the disparity cue, and when they disagree, they have little effect; and (d) simplifying assumptions common in the cue combination literature is often justified for estimating tilt in natural scenes. The fact that tilt estimates are typically not very accurate is consistent with subjective impressions from viewing small patches of natural scene. The fact that estimates are substantially more accurate for a subset of image locations is also consistent with subjective impressions and with the hypothesis that perceived surface orientation, at more global scales, is achieved by interpolation or extrapolation from estimates at key locations. PMID:27738702

  20. Human muscle sympathetic neural and haemodynamic responses to tilt following spaceflight

    Science.gov (United States)

    Levine, Benjamin D.; Pawelczyk, James A.; Ertl, Andrew C.; Cox, James F.; Zuckerman, Julie H.; Diedrich, Andre; Biaggioni, Italo; Ray, Chester A.; Smith, Michael L.; Iwase, Satoshi; hide

    2002-01-01

    Orthostatic intolerance is common when astronauts return to Earth: after brief spaceflight, up to two-thirds are unable to remain standing for 10 min. Previous research suggests that susceptible individuals are unable to increase their systemic vascular resistance and plasma noradrenaline concentrations above pre-flight upright levels. In this study, we tested the hypothesis that adaptation to the microgravity of space impairs sympathetic neural responses to upright posture on Earth. We studied six astronauts approximately 72 and 23 days before and on landing day after the 16 day Neurolab space shuttle mission. We measured heart rate, arterial pressure and cardiac output, and calculated stroke volume and total peripheral resistance, during supine rest and 10 min of 60 deg upright tilt. Muscle sympathetic nerve activity was recorded in five subjects, as a direct measure of sympathetic nervous system responses. As in previous studies, mean (+/- S.E.M.) stroke volume was lower (46 +/- 5 vs. 76 +/- 3 ml, P = 0.017) and heart rate was higher (93 +/- 1 vs. 74 +/- 4 beats min(-1), P = 0.002) during tilt after spaceflight than before spaceflight. Total peripheral resistance during tilt post flight was higher in some, but not all astronauts (1674 +/- 256 vs. 1372 +/- 62 dynes s cm(-5), P = 0.32). No crew member exhibited orthostatic hypotension or presyncopal symptoms during the 10 min of postflight tilting. Muscle sympathetic nerve activity was higher post flight in all subjects, in supine (27 +/- 4 vs. 17 +/- 2 bursts min(-1), P = 0.04) and tilted (46 +/- 4 vs. 38 +/- 3 bursts min(-1), P = 0.01) positions. A strong (r(2) = 0.91-1.00) linear correlation between left ventricular stroke volume and muscle sympathetic nerve activity suggested that sympathetic responses were appropriate for the haemodynamic challenge of upright tilt and were unaffected by spaceflight. We conclude that after 16 days of spaceflight, muscle sympathetic nerve responses to upright tilt are normal.

  1. TILT ANGLE AND FOOTPOINT SEPARATION OF SMALL AND LARGE BIPOLAR SUNSPOT REGIONS OBSERVED WITH HMI

    Energy Technology Data Exchange (ETDEWEB)

    McClintock, B. H. [University of Southern Queensland, Toowoomba, 4350 (Australia); Norton, A. A., E-mail: u1049686@umail.usq.edu.au, E-mail: aanorton@stanford.edu [HEPL, Stanford University, Palo Alto, CA 94305 (United States)

    2016-02-10

    We investigate bipolar sunspot regions and how tilt angle and footpoint separation vary during emergence and decay. The Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory collects data at a higher cadence than historical records and allows for a detailed analysis of regions over their lifetimes. We sample the umbral tilt angle, footpoint separation, and umbral area of 235 bipolar sunspot regions in Helioseismic and Magnetic Imager—Debrecen Data with an hourly cadence. We use the time when the umbral area peaks as time zero to distinguish between the emergence and decay periods of each region and we limit our analysis of tilt and separation behavior over time to within ±96 hr of time zero. Tilt angle evolution is distinctly different for regions with small (≈30 MSH), midsize (≈50 MSH), and large (≈110 MSH) maximum umbral areas, with 45 and 90 MSH being useful divisions for separating the groups. At the peak umbral area, we determine median tilt angles for small (7.°6), midsize (5.°9), and large (9.°3) regions. Within ±48 hr of the time of peak umbral area, large regions steadily increase in tilt angle, midsize regions are nearly constant, and small regions show evidence of negative tilt during emergence. A period of growth in footpoint separation occurs over a 72-hr period for all of the regions from roughly 40 to 70 Mm. The smallest bipoles (<9 MSH) are outliers in that they do not obey Joy's law and have a much smaller footpoint separation. We confirm the Muñoz-Jaramillo et al. results that the sunspots appear to be two distinct populations.

  2. 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.

  3. On minimally parametric primordial power spectrum reconstruction and the evidence for a red tilt

    International Nuclear Information System (INIS)

    Verde, Licia; Peiris, Hiranya

    2008-01-01

    The latest cosmological data seem to indicate a significant deviation from scale invariance of the primordial power spectrum when parameterized either by a power law or by a spectral index with non-zero 'running'. This deviation, by itself, serves as a powerful tool for discriminating among theories for the origin of cosmological structures such as inflationary models. Here, we use a minimally parametric smoothing spline technique to reconstruct the shape of the primordial power spectrum. This technique is well suited to searching for smooth features in the primordial power spectrum such as deviations from scale invariance or a running spectral index, although it would recover sharp features of high statistical significance. We use the WMAP three-year results in combination with data from a suite of higher resolution cosmic microwave background experiments (including the latest ACBAR 2008 release), as well as large-scale structure data from SDSS and 2dFGRS. We employ cross-validation to assess, using the data themselves, the optimal amount of smoothness in the primordial power spectrum consistent with the data. This minimally parametric reconstruction supports the evidence for a power law primordial power spectrum with a red tilt, but not for deviations from a power law power spectrum. Smooth variations in the primordial power spectrum are not significantly degenerate with the other cosmological parameters

  4. Adaptive Neural Network Sliding Mode Control for Quad Tilt Rotor Aircraft

    Directory of Open Access Journals (Sweden)

    Yanchao Yin

    2017-01-01

    Full Text Available A novel neural network sliding mode control based on multicommunity bidirectional drive collaborative search algorithm (M-CBDCS is proposed to design a flight controller for performing the attitude tracking control of a quad tilt rotors aircraft (QTRA. Firstly, the attitude dynamic model of the QTRA concerning propeller tension, channel arm, and moment of inertia is formulated, and the equivalent sliding mode control law is stated. Secondly, an adaptive control algorithm is presented to eliminate the approximation error, where a radial basis function (RBF neural network is used to online regulate the equivalent sliding mode control law, and the novel M-CBDCS algorithm is developed to uniformly update the unknown neural network weights and essential model parameters adaptively. The nonlinear approximation error is obtained and serves as a novel leakage term in the adaptations to guarantee the sliding surface convergence and eliminate the chattering phenomenon, which benefit the overall attitude control performance for QTRA. Finally, the appropriate comparisons among the novel adaptive neural network sliding mode control, the classical neural network sliding mode control, and the dynamic inverse PID control are examined, and comparative simulations are included to verify the efficacy of the proposed control method.

  5. Experimental test of static and dynamic characteristics of tilting-pad thrust bearings

    Directory of Open Access Journals (Sweden)

    Annan Guo

    2015-07-01

    Full Text Available The axial vibration in turbine machine has attracted more and more interest. Tilting-pad thrust bearings are widely used in turbine machines to support the axial load. The dynamic properties generated by oil film of the thrust pad have important effects on the axial vibration of the rotor-bearing system. It is necessary to develop the method to test the dynamic characteristics of thrust bearings. A new rig has been developed. The facility allows a complete set of bearing operating parameters to be measured. Parameters measured include oil temperatures, oil-film thickness, and pressure. The static load and dynamic load can be added on the thrust bearing in the vertical direction at the same time. The relative and absolute displacement vibrations of the test experimental bearing with the changes of dynamic force are measured, and the dynamic characteristics of the test bearing are obtained. The experimental results show clearly that the operating conditions influence largely on the pad static and dynamic characteristics.

  6. CT study of avascular necrosis of femoral head in adults

    International Nuclear Information System (INIS)

    Liu Jihua; Du Yuqing; Xu Aide

    2000-01-01

    Objective: To study the early and new CT signs of avascular necrosis of femoral head in adults. Methods: The CT scans of 127 cases with this condition were analyzed. Results: There were 90 hip joints with femoral head normal in shape, including 67 femoral heads with only high-density sclerosis and 23 ones with high-density and low-density areas. In 111 hip joints, the femoral head was depressed and manifested purely high-density sclerosis in 25 and mixed-density areas in 86. Air-filled cysts appeared in 43 femoral heads. In follow-up cases, the changes in shape and density of femoral head followed some rules. Conclusion: Purely high-density sclerosis is an early sign and is of great diagnostic value combined with its special shape. Air in femoral heads is also a sign of the disease

  7. Perceived direction of gravity and the body-axis during static whole body roll-tilt in healthy subjects.

    Science.gov (United States)

    Tamura, Atsushi; Wada, Yoshiro; Inui, Takuo; Shiotani, Akihiro

    2017-10-01

    We used the subjective visual vertical (SVV) and two different subjective visual body axis (SVBA) methods to quantify roll-tilt perception under gravity, and investigated the characteristics of these methods during static roll-tilt. In addition, we independently developed a compact device to facilitate evaluation of SVBA in different gravitational environments. Ten male volunteers participated in this study. We created a roll-tilt environment using a flight simulator in a dark room. The cockpit of the simulator was tilted leftward or rightward (-30°, -20°, -10°, 0°, 10°, 20° and 30°) in each randomly ordered trial. We quantified roll-tilt perception such that the experiment was conducted under 21 different conditions per participant. We found no significant differences among the SVV error and the two types of SVBA error. The SVV and the SVBA methods may be useful for evaluating subjective roll-tilt perception.

  8. Ischemic femoral head osteonecrosis in a piglet model causes three dimensional decrease in acetabular coverage.

    Science.gov (United States)

    Upasani, Vidyadhar V; Jeffords, Megan E; Farnsworth, Christine L; Padilla, David; Lopreiato, Nick; Aruwajoye, Olumide O; Kim, Harry K W

    2017-09-15

    Legg-Calve-Perthes disease (LCPD) is a childhood form of ischemic osteonecrosis marked by development of severe femoral head deformity and premature osteoarthritis. The pathogenesis of femoral head deformity has been studied extensively using a piglet model of ischemic osteonecrosis, however, accompanying acetabular changes have not been investigated. The purpose of this study was to determine if acetabular changes accompany femoral head deformity in a well-established piglet model of LCPD and to define the acetabular changes using three dimensional computed tomography (3-D CT) and modeling. Twenty-four piglets were surgically induced with ischemic osteonecrosis on the right side. The contralateral hip was used as control. At 8 weeks postoperative, pelvi were retrieved and imaged with CT. Custom software was used to measure acetabular morphologic parameters on 3-D CT images. Moderate to severe femoral head deformities were present in all animals. Acetabula with accompanying femoral head deformity had a significant decrease in acetabular version and tilt (p femoral head deformity following ischemic osteonecrosis produces specific and predictable changes to the shape of the acetabulum. Acetabular changes described in patients with LCPD were observed in the piglet model. This model may serve as a valuable tool to elucidate the relationship between femoral head and acetabular deformities. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  9. Tilt signals associated with a small eruption at Asama Volcano, Japan

    Science.gov (United States)

    Ohminato, T.

    2013-12-01

    It is well known that the acceleration input to a seismometer consists of translational acceleration and tilt-related acceleration. The lower the frequency is, the more contribution is from the tilt-related acceleration. The tilt contribution can be easily extracted from the velocity output of broadband seismometers by the following simple procedure. The roll-off of the transfer function of the broadband seismometer in the frequency range below its characteristic frequency is proportional to the square of frequency. It means that the sensor output in this frequency range is proportional to the time-derivative of the ground acceleration. The result of time integration of the signal in this frequency range is, thus proportional to the ground acceleration, which are proportional to the ground tilt. As long as we concentrate on the low enough frequency range, this simple integration procedure is equivalent to the traditional procedure of sensor-response removal followed by transfer to the tilt response On February 2, 2009, a small eruption occurred at Mt. Asama, central Japan. A broadband seismic network operated by Earthquake Research Institute, University of Tokyo, detected tilt-related signals during the eruption. According to the tilt signals that were extracted by the above mentioned procedure, an inflation started 30 minutes before the summit eruption. The inflation was followed by a rapid deflation due to the summit eruption. At the stations relatively far from the summit, while the tilt changes before the eruption were below noise level and thus were not detected, the tilt changes after the eruption were clearly detected by most of the stations around Mt. Asama. The post eruption tilt signals were oriented not to the summit but to the northwestern side of Mt. Asama. The tilt signals before and during the eruption observed at the near-summit stations are interpreted as an accumulation and release of pressure beneath the summit crater before and after the

  10. Optimal tilt-angles of all-glass evacuated tube solar collectors

    International Nuclear Information System (INIS)

    Tang, Runsheng; Gao, Wenfeng; Yu, Yamei; Chen, Hua

    2009-01-01

    In this paper, a detailed mathematical procedure is developed to estimate daily collectible radiation on single tube of all-glass evacuated tube solar collectors based on solar geometry, knowledge of two-dimensional radiation transfer. Results shows that the annual collectible radiation on a tube is affected by many factors such as collector type, central distance between tubes, size of solar tubes, tilt and azimuth angles, use of diffuse flat reflector (DFR, in short); For collectors with identical parameters, T-type collectors (collectors with solar tubes tilt-arranged) annually collect slightly more radiation than H-type collectors (those with solar tubes horizontally arranged) do. The use of DFR can significantly improve the energy collection of collectors. Unlike the flat-plate collectors, all-glass evacuated tube solar collectors should be generally mounted with a tilt-angle less than the site latitude in order to maximize the annual energy collection. For most areas with the site latitude larger than 30 o in China, T-type collectors should be installed with a tilt-angle about 10 o less than the site latitude, whereas for H-type collectors without DFR, the reasonable tilt-angle should be about 20 o less than the site latitude. Effects of some parameters on the annual collectible radiation on the collectors are also presented.

  11. Design of a Piezoelectric-Driven Tilt Mirror for a Fast Laser Scanner

    Science.gov (United States)

    Park, Jung-Ho; Lee, Hu-Seung; Lee, Jae-Hoon; Yun, So-Nam; Ham, Young-Bog; Yun, Dong-Won

    2012-09-01

    Recently, laser scanners have been used for laser processing such as cutting, welding, and grooving, especially in the automotive industry. The laser scanners need a high-speed driving to minimize cracks caused by thermal shock of brittle materials. Therefore, a novel laser processing system that is composed of a laser source and a piezoelectric-driven tilt mirror to control the reflection angle of the laser beam, and a stage equipped with the tilt mirror has been investigated. In this study, a piezoelectric-driven tilt mirror is designed and analyzed for scanning performance to achieve a beam spot of 30 µm, a pattern width of 1 mm, an overlap ratio of 70% of the circle area, and a scanning speed of 1 m/s. Then, structural analysis of the tilt mirror with three piezoelectric actuators is performed to determine the maximum reflection angle and resonance frequency. Finally, a prototype tilt mirror is fabricated and its basic characteristics are experimentally investigated and discussed.

  12. Micromirror with large-tilting angle using Fe-based metallic glass.

    Science.gov (United States)

    Lee, Jae-Wung; Lin, Yu-Ching; Kaushik, Neelam; Sharma, Parmanand; Makino, Akihiro; Inoue, Akihisa; Esashi, Masayoshi; Gessner, Thomas

    2011-09-01

    For enhancing the micromirror properties like tilting angle and stability during actuation, Fe-based metallic glass (MG) was applied for torsion bar material. A micromirror with mirror-plate diameter of 900 μm and torsion bar dimensions length 250 μm, width 30 μm and thickness 2.5 μm was chosen for the tilting angle tests, which were performed by permanent magnets and electromagnet setup. An extremely large tilting angle of over -270° was obtained from an activation test by permanent magnet that has approximately 0.2 T of magnetic strength. A large mechanical tilting angle of over -70° was obtained by applying approximately 1.1 mT to the mirror when 93 mAwas applied to solenoid setup. The large-tilting angle of the micromirror is due to the torsion bar, which was fabricated with Fe-based MG thin film that has large elastic strain limit, fracture toughness, and excellent magnetic property.

  13. 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.

  14. 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.

  15. Establishment of Approximate Analytical Model of Oil Film Force for Finite Length Tilting Pad Journal Bearings

    Directory of Open Access Journals (Sweden)

    Yongliang Wang

    2015-01-01

    Full Text Available Tilting pad bearings offer unique dynamic stability enabling successful deployment of high-speed rotating machinery. The model of dynamic stiffness, damping, and added mass coefficients is often used for rotordynamic analyses, and this method does not suffice to describe the dynamic behaviour due to the nonlinear effects of oil film force under larger shaft vibration or vertical rotor conditions. The objective of this paper is to present a nonlinear oil force model for finite length tilting pad journal bearings. An approximate analytic oil film force model was established by analysing the dynamic characteristic of oil film of a single pad journal bearing using variable separation method under the dynamic π oil film boundary condition. And an oil film force model of a four-tilting-pad journal bearing was established by using the pad assembly technique and considering pad tilting angle. The validity of the model established was proved by analyzing the distribution of oil film pressure and the locus of journal centre for tilting pad journal bearings and by comparing the model established in this paper with the model established using finite difference method.

  16. 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.

  17. Comparison of decentration and tilt between one piece and three piece polymethyl methacrylate intraocular lenses

    Science.gov (United States)

    Hayashi, K.; Hayashi, H.; Nakao, F.; Hayashi, F.

    1998-01-01

    BACKGROUND—The extent of the decentration and tilt was prospectively compared between one piece polymethyl methacrylate (PMMA) and three piece PMMA intraocular lenses (IOLs) which were implanted in the capsular bag after performing continuous curvilinear capsulorhexis.
METHODS—91 patients underwent a one piece PMMA IOL implantation in one eye as well as the implantation of the three piece PMMA IOL with polyvinylidene fluoride loops in the opposite eye. The length of the lens decentration and the angle of the tilt were quantitated using the anterior eye segment analysis system (EAS-1000) at 1 week as well as 1, 3, and 6 months postoperatively.
RESULTS—The mean length of the decentration in the one piece IOL was smaller than that in the three piece IOL at 1 week (p=0.0092), 1 month (p=0.0044), 3 months (p=0.0069), and 6 months (p=0.0010) postoperatively. However, no significant difference was found in the degree of the tilt between the two types of IOLs throughout the observation periods.
CONCLUSION—These results clarified that the one piece PMMA IOL with rigid PMMA haptics implanted in the capsular bag provides a better centration than the three piece PMMA IOL with flexible haptics, whereas the tilt was the same between the two types of IOLs.

 Keywords: intraocular lens; decentration; tilt; continuous curvilinear capsulorhexis PMID:9640193

  18. Effects of errors in velocity tilt on maximum longitudinal compression during neutralized drift compression of intense beam pulses: I. general description

    Energy Technology Data Exchange (ETDEWEB)

    Kaganovich, Igor D.; Massidda, Scottt; Startsev, Edward A.; Davidson, Ronald C.; Vay, Jean-Luc; Friedman, Alex

    2012-06-21

    Neutralized drift compression offers an effective means for particle beam pulse compression and current amplification. In neutralized drift compression, a linear longitudinal velocity tilt (head-to-tail gradient) is applied to the non-relativistic beam pulse, so that the beam pulse compresses as it drifts in the focusing section. The beam current can increase by more than a factor of 100 in the longitudinal direction. We have performed an analytical study of how errors in the velocity tilt acquired by the beam in the induction bunching module limit the maximum longitudinal compression. It is found that the compression ratio is determined by the relative errors in the velocity tilt. That is, one-percent errors may limit the compression to a factor of one hundred. However, a part of the beam pulse where the errors are small may compress to much higher values, which are determined by the initial thermal spread of the beam pulse. It is also shown that sharp jumps in the compressed current density profile can be produced due to overlaying of different parts of the pulse near the focal plane. Examples of slowly varying and rapidly varying errors compared to the beam pulse duration are studied. For beam velocity errors given by a cubic function, the compression ratio can be described analytically. In this limit, a significant portion of the beam pulse is located in the broad wings of the pulse and is poorly compressed. The central part of the compressed pulse is determined by the thermal spread. The scaling law for maximum compression ratio is derived. In addition to a smooth variation in the velocity tilt, fast-changing errors during the pulse may appear in the induction bunching module if the voltage pulse is formed by several pulsed elements. Different parts of the pulse compress nearly simultaneously at the target and the compressed profile may have many peaks. The maximum compression is a function of both thermal spread and the velocity errors. The effects of the

  19. Head first Ajax

    CERN Document Server

    Riordan, Rebecca M

    2008-01-01

    Ajax is no longer an experimental approach to website development, but the key to building browser-based applications that form the cornerstone of Web 2.0. Head First Ajax gives you an up-to-date perspective that lets you see exactly what you can do -- and has been done -- with Ajax. With it, you get a highly practical, in-depth, and mature view of what is now a mature development approach. Using the unique and highly effective visual format that has turned Head First titles into runaway bestsellers, this book offers a big picture overview to introduce Ajax, and then explores the use of ind

  20. Head First Statistics

    CERN Document Server

    Griffiths, Dawn

    2009-01-01

    Wouldn't it be great if there were a statistics book that made histograms, probability distributions, and chi square analysis more enjoyable than going to the dentist? Head First Statistics brings this typically dry subject to life, teaching you everything you want and need to know about statistics through engaging, interactive, and thought-provoking material, full of puzzles, stories, quizzes, visual aids, and real-world examples. Whether you're a student, a professional, or just curious about statistical analysis, Head First's brain-friendly formula helps you get a firm grasp of statistics