Dual processing of visual rotation for bipedal stance control.

PubMed

Day, Brian L; Muller, Timothy; Offord, Joanna; Di Giulio, Irene

2016-10-01

When standing, the gain of the body-movement response to a sinusoidally moving visual scene has been shown to get smaller with faster stimuli, possibly through changes in the apportioning of visual flow to self-motion or environment motion. We investigated whether visual-flow speed similarly influences the postural response to a discrete, unidirectional rotation of the visual scene in the frontal plane. Contrary to expectation, the evoked postural response consisted of two sequential components with opposite relationships to visual motion speed. With faster visual rotation the early component became smaller, not through a change in gain but by changes in its temporal structure, while the later component grew larger. We propose that the early component arises from the balance control system minimising apparent self-motion, while the later component stems from the postural system realigning the body with gravity. The source of visual motion is inherently ambiguous such that movement of objects in the environment can evoke self-motion illusions and postural adjustments. Theoretically, the brain can mitigate this problem by combining visual signals with other types of information. A Bayesian model that achieves this was previously proposed and predicts a decreasing gain of postural response with increasing visual motion speed. Here we test this prediction for discrete, unidirectional, full-field visual rotations in the frontal plane of standing subjects. The speed (0.75-48 deg s(-1) ) and direction of visual rotation was pseudo-randomly varied and mediolateral responses were measured from displacements of the trunk and horizontal ground reaction forces. The behaviour evoked by this visual rotation was more complex than has hitherto been reported, consisting broadly of two consecutive components with respective latencies of ∼190 ms and >0.7 s. Both components were sensitive to visual rotation speed, but with diametrically opposite relationships. Thus, the early component decreased with faster visual rotation, while the later component increased. Furthermore, the decrease in size of the early component was not achieved by a simple attenuation of gain, but by a change in its temporal structure. We conclude that the two components represent expressions of different motor functions, both pertinent to the control of bipedal stance. We propose that the early response stems from the balance control system attempting to minimise unintended body motion, while the later response arises from the postural control system attempting to align the body with gravity. © 2016 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

Tendency to Mirror-Image on a Visual Memory Test.

ERIC Educational Resources Information Center

Aliotti, Nicholas C.

1980-01-01

Young children (153 normal preschool and primary graders, 19 cerebral palsied 5 to 15 year olds, and 16 learning disabled 7 to 12 year olds) were given a test of immediate visual memory which required selection of a geometric design from among six alternatives, including a mirror image and a rotation. (CL)

Flow visualization around a rotating body in a wind tunnel

NASA Astrophysics Data System (ADS)

Hiraki, K.; Zaitsu, D.; Yanaga, Y.; Kleine, H.

2017-02-01

The rotational behavior of capsule-shaped models is investigated in the transonic wind tunnel of JAXA. A special support is developed to allow the model to rotate around the pitch, yaw and roll axes. This 3-DOF free rotational mounting apparatus achieves the least frictional torque from the support and the instruments. Two types of capsule models are prepared, one is drag type (SPH model) and the other is lift type (HTV-R model). The developed mounting apparatus is used in the wind tunnel tests with these capsule models. In a flow of Mach 0.9, the SPH model exhibits oscillations in pitch and yaw, and it rolls half a turn during the test. Similarly, the HTV-R model exhibits pitch and yaw oscillations in a flow of Mach 0.5. Moreover, it rolls multiple times during the test. In order to investigate the flow field around the capsule, the combined technique of color schlieren and surface tufts is applied. This visualization clearly shows the flow reattachment on the back surface of a capsule, which is suspected to induce the rapid rolling motion.

Factors of Spatial Visualization: An Analysis of the PSVT:R

ERIC Educational Resources Information Center

Ernst, Jeremy V.; Willams, Thomas O.; Clark, Aaron C.; Kelly, Daniel P.

2017-01-01

The Purdue Spatial Visualization Test: Visualization of Rotations (PVST:R) is among the most commonly used measurement instruments to assess spatial ability among engineering students. Previous analysis that explores the factor structure of the PSVT:R indicates a single-factor measure of the instrument. With this as a basis, this research seeks to…

Translation and Rotation Trade Off in Human Visual Heading Estimation

NASA Technical Reports Server (NTRS)

Stone, Leland S.; Perrone, John A.; Null, Cynthia H. (Technical Monitor)

1996-01-01

We have previously shown that, during simulated curvilinear motion, humans can make reasonably accurate and precise heading judgments from optic flow without either oculomotor or static-depth cues about rotation. We now systematically investigate the effect of varying the parameters of self-motion. We visually simulated 400 ms of self-motion along curved paths (constant rotation and translation rates, fixed retinocentric heading) towards two planes of random dots at 10.3 m and 22.3 m at mid-trial. Retinocentric heading judgments of 4 observers (2 naive) were measured for 12 different combinations of translation (T between 4 and 16 m/s) and rotation (R either 8 or 16 deg/s). In the range tested, heading bias and uncertainty decrease quasilinearly with T/R, but the bias also appears to depend on R. If depth is held constant, the ratio T/R can account for much of the variation in the accuracy and precision of human visual heading estimation, although further experiments are needed to resolve whether absolute rotation rate, total flow rate, or some other factor can account for the observed -2 deg shift between the bias curves.

Visual information processing in the lion-tailed macaque (Macaca silenus): mental rotation or rotational invariance?

PubMed

Burmann, Britta; Dehnhardt, Guido; Mauck, Björn

2005-01-01

Mental rotation is a widely accepted concept indicating an image-like mental representation of visual information and an analogue mode of information processing in certain visuospatial tasks. In the task of discriminating between image and mirror-image of rotated figures, human reaction times increase with the angular disparity between the figures. In animals, tests of this kind yield inconsistent results. Pigeons were found to use a time-independent rotational invariance, possibly indicating a non-analogue information processing system that evolved in response to the horizontal plane of reference birds perceive during flight. Despite similar ecological demands concerning the visual reference plane, a sea lion was found to use mental rotation in similar tasks, but its processing speed while rotating three-dimensional stimuli seemed to depend on the axis of rotation in a different way than found for humans in similar tasks. If ecological demands influence the way information processing systems evolve, hominids might have secondarily lost the ability of rotational invariance while retreating from arboreal living and evolving an upright gait in which the vertical reference plane is more important. We therefore conducted mental rotation experiments with an arboreal living primate species, the lion-tailed macaque. Performing a two-alternative matching-to-sample procedure, the animal had to decide between rotated figures representing image and mirror-image of a previously shown upright sample. Although non-rotated stimuli were recognized faster than rotated ones, the animal's mean reaction times did not clearly increase with the angle of rotation. These results are inconsistent with the mental rotation concept but also cannot be explained assuming a mere rotational invariance. Our study thus seems to support the idea of information processing systems evolving gradually in response to specific ecological demands.

Sex differences in a chronometric mental rotation test with cube figures: a behavioral, electroencephalography, and eye-tracking pilot study.

PubMed

Scheer, Clara; Mattioni Maturana, Felipe; Jansen, Petra

2018-05-07

In chronometric mental rotation tasks, sex differences are widely discussed. Most studies find men to be more skilled in mental rotation than women, which can be explained by the holistic strategy that they use to rotate stimuli. Women are believed to apply a piecemeal strategy. So far, there have been no studies investigating this phenomenon using eye-tacking methods in combination with electroencephalography (EEG) analysis: the present study compared behavioral responses, EEG activity, and eye movements of 15 men and 15 women while solving a three-dimensional chronometric mental rotation test. The behavioral analysis showed neither differences in reaction time nor in the accuracy rate between men and women. The EEG data showed a higher right activation on parietal electrodes for women and the eye-tracking results indicated a longer fixation in a higher number of areas of interest at 0° for women. Men and women are likely to possess different perceptual (visual search) and decision-making mechanisms, but similar mental rotation processes. Furthermore, men presented a longer visual search processing, characterized by the greater saccade latency of 0°-135°. Generally, this study could be considered a pilot study to investigate sex differences in mental rotation tasks while combining eye-tracking and EEG methods.

Congenitally blind individuals rapidly adapt to coriolis force perturbations of their reaching movements

NASA Technical Reports Server (NTRS)

DiZio, P.; Lackner, J. R.

2000-01-01

Reaching movements made to visual targets in a rotating room are initially deviated in path and endpoint in the direction of transient Coriolis forces generated by the motion of the arm relative to the rotating environment. With additional reaches, movements become progressively straighter and more accurate. Such adaptation can occur even in the absence of visual feedback about movement progression or terminus. Here we examined whether congenitally blind and sighted subjects without visual feedback would demonstrate adaptation to Coriolis forces when they pointed to a haptically specified target location. Subjects were tested pre-, per-, and postrotation at 10 rpm counterclockwise. Reaching to straight ahead targets prerotation, both groups exhibited slightly curved paths. Per-rotation, both groups showed large initial deviations of movement path and curvature but within 12 reaches on average had returned to prerotation curvature levels and endpoints. Postrotation, both groups showed mirror image patterns of curvature and endpoint to the per-rotation pattern. The groups did not differ significantly on any of the performance measures. These results provide compelling evidence that motor adaptation to Coriolis perturbations can be achieved on the basis of proprioceptive, somatosensory, and motor information in the complete absence of visual experience.

Does letter rotation slow down orthographic processing in word recognition?

PubMed

Perea, Manuel; Marcet, Ana; Fernández-López, María

2018-02-01

Leading neural models of visual word recognition assume that letter rotation slows down the conversion of the visual input to a stable orthographic representation (e.g., local detectors combination model; Dehaene, Cohen, Sigman, & Vinckier, 2005, Trends in Cognitive Sciences, 9, 335-341). If this premise is true, briefly presented rotated primes should be less effective at activating word representations than those primes with upright letters. To test this question, we conducted a masked priming lexical decision experiment with vertically presented words either rotated 90° or in marquee format (i.e., vertically but with upright letters). We examined the impact of the format on both letter identity (masked identity priming: identity vs. unrelated) and letter position (masked transposed-letter priming: transposed-letter prime vs. replacement-letter prime). Results revealed sizeable masked identity and transposed-letter priming effects that were similar in magnitude for rotated and marquee words. Therefore, the reading cost from letter rotation does not arise in the initial access to orthographic/lexical representations.

Effect of feedback techniques for lower back pain on gluteus maximus and oblique abdominal muscle activity and angle of pelvic rotation during the clam exercise.

PubMed

Koh, Eun-Kyung; Park, Kyue-Nam; Jung, Do-Young

2016-11-01

This study was conducted in order to determine the effect of feedback tools on activities of the gluteus maximus (Gmax) and oblique abdominal muscles and the angle of pelvic rotation during clam exercise (CE). Comparative study using repeated measures. University laboratory. Sixteen subjects with lower back pain. Each subject performed the CE without feedback, the CE using a pressure biofeedback unit (CE-PBU), and the CE with palpation and visual feedback (CE-PVF). Electromyographic (EMG) activity and the angles of pelvic rotation were measured using surface EMG and a three-dimensional motion-analysis system, respectively. One-way repeated-measures ANOVA followed by the Bonferroni post hoc test were used to compare the EMG activity in each muscle as well as the angle of pelvic rotation during the CE, CE-PBU, and CE-PVF. The results of post-hoc testing showed a significantly reduced angle of pelvic rotation and significantly more Gmax EMG activity during the CE-PVF compared with during the CE and CE-PBU. These findings suggest that palpation and visual feedback is effective for activating the Gmax and controlling pelvic rotation during the CE in subjects with lower back pain. Copyright © 2016 Elsevier Ltd. All rights reserved.

The Relationship Between Online Visual Representation of a Scene and Long-Term Scene Memory

ERIC Educational Resources Information Center

Hollingworth, Andrew

2005-01-01

In 3 experiments the author investigated the relationship between the online visual representation of natural scenes and long-term visual memory. In a change detection task, a target object either changed or remained the same from an initial image of a natural scene to a test image. Two types of changes were possible: rotation in depth, or…

Aging and Sensory Substitution in a Virtual Navigation Task.

PubMed

Levy-Tzedek, S; Maidenbaum, S; Amedi, A; Lackner, J

2016-01-01

Virtual environments are becoming ubiquitous, and used in a variety of contexts-from entertainment to training and rehabilitation. Recently, technology for making them more accessible to blind or visually impaired users has been developed, by using sound to represent visual information. The ability of older individuals to interpret these cues has not yet been studied. In this experiment, we studied the effects of age and sensory modality (visual or auditory) on navigation through a virtual maze. We added a layer of complexity by conducting the experiment in a rotating room, in order to test the effect of the spatial bias induced by the rotation on performance. Results from 29 participants showed that with the auditory cues, it took participants a longer time to complete the mazes, they took a longer path length through the maze, they paused more, and had more collisions with the walls, compared to navigation with the visual cues. The older group took a longer time to complete the mazes, they paused more, and had more collisions with the walls, compared to the younger group. There was no effect of room rotation on the performance, nor were there any significant interactions among age, feedback modality and room rotation. We conclude that there is a decline in performance with age, and that while navigation with auditory cues is possible even at an old age, it presents more challenges than visual navigation.

Using visuo-kinetic virtual reality to induce illusory spinal movement: the MoOVi Illusion

PubMed Central

Smith, Ross T.; Hunter, Estin V.; Davis, Miles G.; Sterling, Michele; Moseley, G. Lorimer

2017-01-01

Background Illusions that alter perception of the body provide novel opportunities to target brain-based contributions to problems such as persistent pain. One example of this, mirror therapy, uses vision to augment perceived movement of a painful limb to treat pain. Since mirrors can’t be used to induce augmented neck or other spinal movement, we aimed to test whether such an illusion could be achieved using virtual reality, in advance of testing its potential therapeutic benefit. We hypothesised that perceived head rotation would depend on visually suggested movement. Method In a within-subjects repeated measures experiment, 24 healthy volunteers performed neck movements to 50o of rotation, while a virtual reality system delivered corresponding visual feedback that was offset by a factor of 50%–200%—the Motor Offset Visual Illusion (MoOVi)—thus simulating more or less movement than that actually occurring. At 50o of real-world head rotation, participants pointed in the direction that they perceived they were facing. The discrepancy between actual and perceived direction was measured and compared between conditions. The impact of including multisensory (auditory and visual) feedback, the presence of a virtual body reference, and the use of 360o immersive virtual reality with and without three-dimensional properties, was also investigated. Results Perception of head movement was dependent on visual-kinaesthetic feedback (p = 0.001, partial eta squared = 0.17). That is, altered visual feedback caused a kinaesthetic drift in the direction of the visually suggested movement. The magnitude of the drift was not moderated by secondary variables such as the addition of illusory auditory feedback, the presence of a virtual body reference, or three-dimensionality of the scene. Discussion Virtual reality can be used to augment perceived movement and body position, such that one can perform a small movement, yet perceive a large one. The MoOVi technique tested here has clear potential for assessment and therapy of people with spinal pain. PMID:28243537

Using visuo-kinetic virtual reality to induce illusory spinal movement: the MoOVi Illusion.

PubMed

Harvie, Daniel S; Smith, Ross T; Hunter, Estin V; Davis, Miles G; Sterling, Michele; Moseley, G Lorimer

2017-01-01

Illusions that alter perception of the body provide novel opportunities to target brain-based contributions to problems such as persistent pain. One example of this, mirror therapy, uses vision to augment perceived movement of a painful limb to treat pain. Since mirrors can't be used to induce augmented neck or other spinal movement, we aimed to test whether such an illusion could be achieved using virtual reality, in advance of testing its potential therapeutic benefit. We hypothesised that perceived head rotation would depend on visually suggested movement. In a within-subjects repeated measures experiment, 24 healthy volunteers performed neck movements to 50 o of rotation, while a virtual reality system delivered corresponding visual feedback that was offset by a factor of 50%-200%-the Motor Offset Visual Illusion (MoOVi)-thus simulating more or less movement than that actually occurring. At 50 o of real-world head rotation, participants pointed in the direction that they perceived they were facing. The discrepancy between actual and perceived direction was measured and compared between conditions. The impact of including multisensory (auditory and visual) feedback, the presence of a virtual body reference, and the use of 360 o immersive virtual reality with and without three-dimensional properties, was also investigated. Perception of head movement was dependent on visual-kinaesthetic feedback ( p  = 0.001, partial eta squared = 0.17). That is, altered visual feedback caused a kinaesthetic drift in the direction of the visually suggested movement. The magnitude of the drift was not moderated by secondary variables such as the addition of illusory auditory feedback, the presence of a virtual body reference, or three-dimensionality of the scene. Virtual reality can be used to augment perceived movement and body position, such that one can perform a small movement, yet perceive a large one. The MoOVi technique tested here has clear potential for assessment and therapy of people with spinal pain.

Mental rotation training: transfer and maintenance effects on spatial abilities.

PubMed

Meneghetti, Chiara; Borella, Erika; Pazzaglia, Francesca

2016-01-01

One of the aims of research in spatial cognition is to examine whether spatial skills can be enhanced. The goal of the present study was thus to assess the benefit and maintenance effects of mental rotation training in young adults. Forty-eight females took part in the study: 16 were randomly assigned to receive the mental rotation training (based on comparing pairs of 2D or 3D objects and rotation games), 16 served as active controls (performing parallel non-spatial activities), and 16 as passive controls. Transfer effects to both untrained spatial tasks (testing both object rotation and perspective taking) and visual and verbal tasks were examined. Across the training sessions, the group given mental rotation training revealed benefits in the time it took to make judgments when comparing 3D and 2D objects, but their mental rotation speed did not improve. When compared with the other groups, the mental rotation training group did show transfer effects, however, in tasks other than those practiced (i.e., in object rotation and perspective-taking tasks), and these benefits persisted after 1 month. The training had no effect on visual or verbal tasks. These findings are discussed from the spatial cognition standpoint and with reference to the (rotation) training literature.

Visual perspective taking impairment in children with autistic spectrum disorder.

PubMed

Hamilton, Antonia F de C; Brindley, Rachel; Frith, Uta

2009-10-01

Evidence from typical development and neuroimaging studies suggests that level 2 visual perspective taking - the knowledge that different people may see the same thing differently at the same time - is a mentalising task. Thus, we would expect children with autism, who fail typical mentalising tasks like false belief, to perform poorly on level 2 visual perspective taking as well. However, prior data on this issue are inconclusive. We re-examined this question, testing a group of 23 young autistic children, aged around 8years with a verbal mental age of around 4years and three groups of typical children (n=60) ranging in age from 4 to 8years on a level 2 visual perspective task and a closely matched mental rotation task. The results demonstrate that autistic children have difficulty with visual perspective taking compared to a task requiring mental rotation, relative to typical children. Furthermore, performance on the level 2 visual perspective taking task correlated with theory of mind performance. These findings resolve discrepancies in previous studies of visual perspective taking in autism, and demonstrate that level 2 visual perspective taking is a mentalising task.

Correlation of visual performance with quality of life and intraocular aberrometric profile in patients implanted with rotationally asymmetric multifocal IOLs.

PubMed

Ramón, María L; Piñero, David P; Pérez-Cambrodí, Rafael J

2012-02-01

To examine the visual performance of a rotationally asymmetric multifocal intraocular lens (IOL) by correlating the defocus curve of the IOL-implanted eye with the intraocular aberrometric profile and impact on the quality of life. A prospective, consecutive, case series study including 26 eyes from 13 patients aged between 50 and 83 years (mean: 65.54±7.59 years) was conducted. All patients underwent bilateral cataract surgery with implantation of a rotationally asymmetric multifocal IOL (Lentis Mplus LS-312 MF30, Oculentis GmbH). Distance and near visual acuity outcomes, intraocular aberrations, defocus curve, and quality of life (assessed using the National Eye Institute Visual Functioning Questionnaire-25) were evaluated postoperatively (mean follow-up: 6.42±2.24 months). A significant improvement in distance visual acuity was found postoperatively (P<.01). Mean postoperative logMAR distance-corrected near visual acuity was 0.19±0.12 (∼20/30). Corrected distance visual acuity and near visual acuity of 20/20 or better were achieved by 30.8% and 7.7% of eyes, respectively. Of all eyes, 96.2% had a postoperative addition between 0 and 1.00 diopter (D). The defocus curve showed two peaks of maximum visual acuity (0 and 3.00 D of defocus), with an acceptable range of intermediate vision. LogMAR visual acuity corresponding to near defocus was directly correlated with some higher order intraocular aberrations (r⩾0.44, P⩽.04). Some difficulties evaluated with the quality of life test correlated directly with near and intermediate visual acuity (r⩾0.50, P⩽.01). The Lentis Mplus multifocal IOL provides good distance, intermediate, and near visual outcomes; however, the induced intraocular aberrometric profile may limit the potential visual benefit. Copyright 2012, SLACK Incorporated.

Visual perception can account for the close relation between numerosity processing and computational fluency.

PubMed

Zhou, Xinlin; Wei, Wei; Zhang, Yiyun; Cui, Jiaxin; Chen, Chuansheng

2015-01-01

Studies have shown that numerosity processing (e.g., comparison of numbers of dots in two dot arrays) is significantly correlated with arithmetic performance. Researchers have attributed this association to the fact that both tasks share magnitude processing. The current investigation tested an alternative hypothesis, which states that visual perceptual ability (as measured by a figure-matching task) can account for the close relation between numerosity processing and arithmetic performance (computational fluency). Four hundred and twenty four third- to fifth-grade children (220 boys and 204 girls, 8.0-11.0 years old; 120 third graders, 146 fourth graders, and 158 fifth graders) were recruited from two schools (one urban and one suburban) in Beijing, China. Six classes were randomly selected from each school, and all students in each selected class participated in the study. All children were given a series of cognitive and mathematical tests, including numerosity comparison, figure matching, forward verbal working memory, visual tracing, non-verbal matrices reasoning, mental rotation, choice reaction time, arithmetic tests and curriculum-based mathematical achievement test. Results showed that figure-matching ability had higher correlations with numerosity processing and computational fluency than did other cognitive factors (e.g., forward verbal working memory, visual tracing, non-verbal matrix reasoning, mental rotation, and choice reaction time). More important, hierarchical multiple regression showed that figure matching ability accounted for the well-established association between numerosity processing and computational fluency. In support of the visual perception hypothesis, the results suggest that visual perceptual ability, rather than magnitude processing, may be the shared component of numerosity processing and arithmetic performance.

Visual perception can account for the close relation between numerosity processing and computational fluency

PubMed Central

Zhou, Xinlin; Wei, Wei; Zhang, Yiyun; Cui, Jiaxin; Chen, Chuansheng

2015-01-01

Studies have shown that numerosity processing (e.g., comparison of numbers of dots in two dot arrays) is significantly correlated with arithmetic performance. Researchers have attributed this association to the fact that both tasks share magnitude processing. The current investigation tested an alternative hypothesis, which states that visual perceptual ability (as measured by a figure-matching task) can account for the close relation between numerosity processing and arithmetic performance (computational fluency). Four hundred and twenty four third- to fifth-grade children (220 boys and 204 girls, 8.0–11.0 years old; 120 third graders, 146 fourth graders, and 158 fifth graders) were recruited from two schools (one urban and one suburban) in Beijing, China. Six classes were randomly selected from each school, and all students in each selected class participated in the study. All children were given a series of cognitive and mathematical tests, including numerosity comparison, figure matching, forward verbal working memory, visual tracing, non-verbal matrices reasoning, mental rotation, choice reaction time, arithmetic tests and curriculum-based mathematical achievement test. Results showed that figure-matching ability had higher correlations with numerosity processing and computational fluency than did other cognitive factors (e.g., forward verbal working memory, visual tracing, non-verbal matrix reasoning, mental rotation, and choice reaction time). More important, hierarchical multiple regression showed that figure matching ability accounted for the well-established association between numerosity processing and computational fluency. In support of the visual perception hypothesis, the results suggest that visual perceptual ability, rather than magnitude processing, may be the shared component of numerosity processing and arithmetic performance. PMID:26441740

Replication of the Hierarchical Visual-Perceptual-Image Rotation Model in De Wolff and Buiten's (1963) Battery of 46 Tests of Mental Ability

ERIC Educational Resources Information Center

Johnson, Wendy; te Nijenhuis, Jan; Bouchard, Thomas J., Jr.

2007-01-01

In two recent papers, Johnson & Bouchard [Johnson, W., & Bouchard, T. J., Jr. (2005a). The structure of human intelligence: It is verbal, perceptual, and image rotation (VPR) , not fluid and crystallized. "Intelligence," 33, 393-416, Johnson W., & Bouchard, T. J., Jr. (2005b). Constructive replication of the visual…

Is digital photography an accurate and precise method for measuring range of motion of the shoulder and elbow?

PubMed

Russo, Russell R; Burn, Matthew B; Ismaily, Sabir K; Gerrie, Brayden J; Han, Shuyang; Alexander, Jerry; Lenherr, Christopher; Noble, Philip C; Harris, Joshua D; McCulloch, Patrick C

2018-03-01

Accurate measurements of shoulder and elbow motion are required for the management of musculoskeletal pathology. The purpose of this investigation was to compare three techniques for measuring motion. The authors hypothesized that digital photography would be equivalent in accuracy and show higher precision compared to the other two techniques. Using infrared motion capture analysis as the reference standard, shoulder flexion/abduction/internal rotation/external rotation and elbow flexion/extension were measured using visual estimation, goniometry, and digital photography on 10 fresh frozen cadavers. These measurements were performed by three physical therapists and three orthopaedic surgeons. Accuracy was defined by the difference from the reference standard (motion capture analysis), while precision was defined by the proportion of measurements within the authors' definition of clinical significance (10° for all motions except for elbow extension where 5° was used). Analysis of variance (ANOVA), t-tests, and chi-squared tests were used. Although statistically significant differences were found in measurement accuracy between the three techniques, none of these differences met the authors' definition of clinical significance. Precision of the measurements was significantly higher for both digital photography (shoulder abduction [93% vs. 74%, p < 0.001], shoulder internal rotation [97% vs. 83%, p = 0.001], and elbow flexion [93% vs. 65%, p < 0.001]) and goniometry (shoulder abduction [92% vs. 74%, p < 0.001] and shoulder internal rotation [94% vs. 83%, p = 0.008]) than visual estimation. Digital photography was more precise than goniometry for measurements of elbow flexion only [93% vs. 76%, p < 0.001]. There was no clinically significant difference in measurement accuracy between the three techniques for shoulder and elbow motion. Digital photography showed higher measurement precision compared to visual estimation for shoulder abduction, shoulder internal rotation, and elbow flexion. However, digital photography was only more precise than goniometry for measurements of elbow flexion. Overall digital photography shows equivalent accuracy to visual estimation and goniometry, but with higher precision than visual estimation. Copyright © 2017. Published by Elsevier B.V.

The Association Between Visual Assessment of Quality of Movement and Three-Dimensional Analysis of Pelvis, Hip, and Knee Kinematics During a Lateral Step Down Test.

PubMed

Rabin, Alon; Portnoy, Sigal; Kozol, Zvi

2016-11-01

Rabin, A, Portnoy, S, and Kozol, Z. The association between visual assessment of quality of movement and three-dimensional analysis of pelvis, hip, and knee kinematics during a lateral step down test. J Strength Cond Res 30(11): 3204-3211, 2016-Altered movement patterns including contralateral pelvic drop, increased hip adduction, knee abduction, and external rotation have been previously implicated in several lower extremity pathologies. Although various methods exist for assessing movement patterns, real-time visual observation is the most readily available method. The purpose of this study was to determine whether differing visual ratings of trunk, pelvis, and knee alignment, as well as overall quality of movement, are associated with differences in 3-dimensional trunk, pelvis, hip, or knee kinematics during a lateral step down test. Trunk, pelvis, and knee alignment of 30 healthy participants performing the lateral step down were visually rated as "good" or "faulty" based on previously established criteria. An additional categorization of overall quality of movement as either good or moderate was performed based on the aggregate score of each individual rating criterion. Three-dimensional motion analysis of trunk, pelvis, hip, and knee kinematics was simultaneously performed. A faulty pelvis alignment displayed a greater peak contralateral pelvic drop (effect size [ES], 1.65; p < 0.01) and a greater peak hip adduction (ES: 1.04, p = 0.01) compared with participants with a good pelvis alignment. Participants with a faulty knee alignment displayed greater peak knee external rotation compared with participants with a good knee alignment (ES, 0.78; p = 0.02). Participants with an overall moderate quality of movement displayed increased peak contralateral pelvic drop (ES, 1.07; p = 0.01) and peak knee external rotation (ES, 0.72; p = 0.04) compared with those with an overall good quality of movement. Visual rating of quality of movement during a lateral step down test, as performed by an experienced physical therapist, is associated with differences in several kinematics previously implicated in various pathologies.

The Effects of Spatial Visualization Skill Training on Gender and Retention in Engineering.

ERIC Educational Resources Information Center

Devon, Richard; Engel, Renata; Turner, Geoffrey

1998-01-01

Engineering students were given a mental rotation test at the beginning and end of their first-year engineering course and again several years later to assess the relationship between spatial visualization skill and retention in engineering. No relationship was found between task scores and retention; however, a course in design and graphics…

Influence of visual path information on human heading perception during rotation.

PubMed

Li, Li; Chen, Jing; Peng, Xiaozhe

2009-03-31

How does visual path information influence people's perception of their instantaneous direction of self-motion (heading)? We have previously shown that humans can perceive heading without direct access to visual path information. Here we vary two key parameters for estimating heading from optic flow, the field of view (FOV) and the depth range of environmental points, to investigate the conditions under which visual path information influences human heading perception. The display simulated an observer traveling on a circular path. Observers used a joystick to rotate their line of sight until deemed aligned with true heading. Four FOV sizes (110 x 94 degrees, 48 x 41 degrees, 16 x 14 degrees, 8 x 7 degrees) and depth ranges (6-50 m, 6-25 m, 6-12.5 m, 6-9 m) were tested. Consistent with our computational modeling results, heading bias increased with the reduction of FOV or depth range when the display provided a sequence of velocity fields but no direct path information. When the display provided path information, heading bias was not influenced as much by the reduction of FOV or depth range. We conclude that human heading and path perception involve separate visual processes. Path helps heading perception when the display does not contain enough optic-flow information for heading estimation during rotation.

Usage of stereoscopic visualization in the learning contents of rotational motion.

PubMed

Matsuura, Shu

2013-01-01

Rotational motion plays an essential role in physics even at an introductory level. In addition, the stereoscopic display of three-dimensional graphics includes is advantageous for the presentation of rotational motions, particularly for depth recognition. However, the immersive visualization of rotational motion has been known to lead to dizziness and even nausea for some viewers. Therefore, the purpose of this study is to examine the onset of nausea and visual fatigue when learning rotational motion through the use of a stereoscopic display. The findings show that an instruction method with intermittent exposure of the stereoscopic display and a simplification of its visual components reduced the onset of nausea and visual fatigue for the viewers, which maintained the overall effect of instantaneous spatial recognition.

Role of visual and non-visual cues in constructing a rotation-invariant representation of heading in parietal cortex

PubMed Central

Sunkara, Adhira

2015-01-01

As we navigate through the world, eye and head movements add rotational velocity patterns to the retinal image. When such rotations accompany observer translation, the rotational velocity patterns must be discounted to accurately perceive heading. The conventional view holds that this computation requires efference copies of self-generated eye/head movements. Here we demonstrate that the brain implements an alternative solution in which retinal velocity patterns are themselves used to dissociate translations from rotations. These results reveal a novel role for visual cues in achieving a rotation-invariant representation of heading in the macaque ventral intraparietal area. Specifically, we show that the visual system utilizes both local motion parallax cues and global perspective distortions to estimate heading in the presence of rotations. These findings further suggest that the brain is capable of performing complex computations to infer eye movements and discount their sensory consequences based solely on visual cues. DOI: http://dx.doi.org/10.7554/eLife.04693.001 PMID:25693417

Accurate Visual Heading Estimation at High Rotation Rate Without Oculomotor or Static-Depth Cues

NASA Technical Reports Server (NTRS)

Stone, Leland S.; Perrone, John A.; Null, Cynthia H. (Technical Monitor)

1995-01-01

It has been claimed that either oculomotor or static depth cues provide the signals about self-rotation necessary approx.-1 deg/s. We tested this hypothesis by simulating self-motion along a curved path with the eyes fixed in the head (plus or minus 16 deg/s of rotation). Curvilinear motion offers two advantages: 1) heading remains constant in retinotopic coordinates, and 2) there is no visual-oculomotor conflict (both actual and simulated eye position remain stationary). We simulated 400 ms of rotation combined with 16 m/s of translation at fixed angles with respect to gaze towards two vertical planes of random dots initially 12 and 24 m away, with a field of view of 45 degrees. Four subjects were asked to fixate a central cross and to respond whether they were translating to the left or right of straight-ahead gaze. From the psychometric curves, heading bias (mean) and precision (semi-interquartile) were derived. The mean bias over 2-5 runs was 3.0, 4.0, -2.0, -0.4 deg for the first author and three naive subjects, respectively (positive indicating towards the rotation direction). The mean precision was 2.0, 1.9, 3.1, 1.6 deg. respectively. The ability of observers to make relatively accurate and precise heading judgments, despite the large rotational flow component, refutes the view that extra-flow-field information is necessary for human visual heading estimation at high rotation rates. Our results support models that process combined translational/rotational flow to estimate heading, but should not be construed to suggest that other cues do not play an important role when they are available to the observer.

Mirrored and rotated stimuli are not the same: A neuropsychological and lesion mapping study.

PubMed

Martinaud, Olivier; Mirlink, Nicolas; Bioux, Sandrine; Bliaux, Evangéline; Champmartin, Cécile; Pouliquen, Dorothée; Cruypeninck, Yohann; Hannequin, Didier; Gérardin, Emmanuel

2016-05-01

Agnosia for mirrored stimuli is a rare clinical deficit. Only eight patients have been reported in the literature so far and little is known about the neural substrates of this agnosia. Using a previously developed experimental test designed to assess this agnosia, namely the Mirror and Orientation Agnosia Test (MOAT), as well as voxel-lesion symptom mapping (VLSM), we tested the hypothesis that focal brain-injured patients with right parietal damage would be impaired in the discrimination between the canonical view of a visual object and its mirrored and rotated images. Thirty-four consecutively recruited patients with a stroke involving the right or left parietal lobe have been included: twenty patients (59%) had a deficit on at least one of the six conditions of the MOAT, fourteen patients (41%) had a deficit on the mirror condition, twelve patients (35%) had a deficit on at least one the four rotated conditions and one had a truly selective agnosia for mirrored stimuli. A lesion analysis showed that discrimination of mirrored stimuli was correlated to the mesial part of the posterior superior temporal gyrus and the lateral part of the inferior parietal lobule, while discrimination of rotated stimuli was correlated to the lateral part of the posterior superior temporal gyrus and the mesial part of the inferior parietal lobule, with only a small overlap between the two. These data suggest that the right visual 'dorsal' pathway is essential for accurate perception of mirrored and rotated stimuli, with a selective cognitive process and anatomical network underlying our ability to discriminate between mirrored images, different from the process of discriminating between rotated images. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dynamic Torsional and Cyclic Fracture Behavior of ProFile Rotary Instruments at Continuous or Reciprocating Rotation as Visualized with High-speed Digital Video Imaging.

PubMed

Tokita, Daisuke; Ebihara, Arata; Miyara, Kana; Okiji, Takashi

2017-08-01

This study examined the dynamic fracture behavior of nickel-titanium rotary instruments in torsional or cyclic loading at continuous or reciprocating rotation by means of high-speed digital video imaging. The ProFile instruments (size 30, 0.06 taper; Dentsply Maillefer, Ballaigues, Switzerland) were categorized into 4 groups (n = 7 in each group) as follows: torsional/continuous (TC), torsional/reciprocating (TR), cyclic/continuous (CC), and cyclic/reciprocating (CR). Torsional loading was performed by rotating the instruments by holding the tip with a vise. For cyclic loading, a custom-made device with a 38° curvature was used. Dynamic fracture behavior was observed with a high-speed camera. The time to fracture was recorded, and the fractured surface was examined with scanning electron microscopy. The TC group initially exhibited necking of the file followed by the development of an initial crack line. The TR group demonstrated opening and closing of a crack according to its rotation in the cutting and noncutting directions, respectively. The CC group separated without any detectable signs of deformation. In the CR group, initial crack formation was recognized in 5 of 7 samples. The reciprocating rotation exhibited a longer time to fracture in both torsional and cyclic fatigue testing (P < .05). The scanning electron microscopic images showed a severely deformed surface in the TR group. The dynamic fracture behavior of NiTi rotary instruments, as visualized with high-speed digital video imaging, varied between the different modes of rotation and different fatigue testing. Reciprocating rotation induced a slower crack propagation and conferred higher fatigue resistance than continuous rotation in both torsional and cyclic loads. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Visuo-vestibular interaction: predicting the position of a visual target during passive body rotation.

PubMed

Mackrous, I; Simoneau, M

2011-11-10

Following body rotation, optimal updating of the position of a memorized target is attained when retinal error is perceived and corrective saccade is performed. Thus, it appears that these processes may enable the calibration of the vestibular system by facilitating the sharing of information between both reference frames. Here, it is assessed whether having sensory information regarding body rotation in the target reference frame could enhance an individual's learning rate to predict the position of an earth-fixed target. During rotation, participants had to respond when they felt their body midline had crossed the position of the target and received knowledge of result. During practice blocks, for two groups, visual cues were displayed in the same reference frame of the target, whereas a third group relied on vestibular information (vestibular-only group) to predict the location of the target. Participants, unaware of the role of the visual cues (visual cues group), learned to predict the location of the target and spatial error decreased from 16.2 to 2.0°, reflecting a learning rate of 34.08 trials (determined from fitting a falling exponential model). In contrast, the group aware of the role of the visual cues (explicit visual cues group) showed a faster learning rate (i.e. 2.66 trials) but similar final spatial error 2.9°. For the vestibular-only group, similar accuracy was achieved (final spatial error of 2.3°), but their learning rate was much slower (i.e. 43.29 trials). Transferring to the Post-test (no visual cues and no knowledge of result) increased the spatial error of the explicit visual cues group (9.5°), but it did not change the performance of the vestibular group (1.2°). Overall, these results imply that cognition assists the brain in processing the sensory information within the target reference frame. Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.

Effects of head tilt on visual field testing with a head-mounted perimeter imo

PubMed Central

Matsumoto, Chota; Nomoto, Hiroki; Numata, Takuya; Eura, Mariko; Yamashita, Marika; Hashimoto, Shigeki; Okuyama, Sachiko; Kimura, Shinji; Yamanaka, Kenzo; Chiba, Yasutaka; Aihara, Makoto; Shimomura, Yoshikazu

2017-01-01

Purpose A newly developed head-mounted perimeter termed “imo” enables visual field (VF) testing without a fixed head position. Because the positional relationship between the subject’s head and the imo is fixed, the effects of head position changes on the test results are small compared with those obtained using a stationary perimeter. However, only ocular counter-roll (OCR) induced by head tilt might affect VF testing. To quantitatively reveal the effects of head tilt and OCR on the VF test results, we investigated the associations among the head-tilt angle, OCR amplitude and VF testing results. Subjects and methods For 20 healthy subjects, we binocularly recorded static OCR (s-OCR) while tilting the subject’s head at an arbitrary angle ranging from 0° to 60° rightward or leftward in 10° increments. By monitoring iris patterns, we evaluated the s-OCR amplitude. We also performed blind spot detection while tilting the subject’s head by an arbitrary angle ranging from 0° to 50° rightward or leftward in 10° increments to calculate the angle by which the blind spot rotates because of head tilt. Results The association between s-OCR amplitude and head-tilt angle showed a sinusoidal relationship. In blind spot detection, the blind spot rotated to the opposite direction of the head tilt, and the association between the rotation angle of the blind spot and the head-tilt angle also showed a sinusoidal relationship. The rotation angle of the blind spot was strongly correlated with the s-OCR amplitude (R2≥0.94, p<0.0001). A head tilt greater than 20° with imo causes interference between adjacent test areas. Conclusions Both the s-OCR amplitude and the rotation angle of the blind spot were correlated with the head-tilt angle by sinusoidal regression. The rotated VF was correlated with the s-OCR amplitude. During perimetry using imo, the change in the subject’s head tilt should be limited to 20°. PMID:28945777

Think spatial: the representation in mental rotation is nonvisual.

PubMed

Liesefeld, Heinrich R; Zimmer, Hubert D

2013-01-01

For mental rotation, introspection, theories, and interpretations of experimental results imply a certain type of mental representation, namely, visual mental images. Characteristics of the rotated representation can be examined by measuring the influence of stimulus characteristics on rotational speed. If the amount of a given type of information influences rotational speed, one can infer that it was contained in the rotated representation. In Experiment 1, rotational speed of university students (10 men, 11 women) was found to be influenced exclusively by the amount of represented orientation-dependent spatial-relational information but not by orientation-independent spatial-relational information, visual complexity, or the number of stimulus parts. As information in mental-rotation tasks is initially presented visually, this finding implies that at some point during each trial, orientation-dependent information is extracted from visual information. Searching for more direct evidence for this extraction, we recorded the EEG of another sample of university students (12 men, 12 women) during mental rotation of the same stimuli. In an early time window, the observed working memory load-dependent slow potentials were sensitive to the stimuli's visual complexity. Later, in contrast, slow potentials were sensitive to the amount of orientation-dependent information only. We conclude that only orientation-dependent information is contained in the rotated representation. (PsycINFO Database Record (c) 2013 APA, all rights reserved).

Cognitive Changes in Presymptomatic Parkinson’s Disease

DTIC Science & Technology

2004-09-01

frontation naming (e.g., Boston Naming Test), verbal flu- Tramadol (analgesic) 1 ency (e.g., COWA), or memory for either verbal or visual- Benzodiazapine...underlie mental rotation deficits in PD. Men help elucidate the nature of these relationships. typically perform better than women on tests of mental

Cognitive styles and mental rotation ability in map learning.

PubMed

Pazzaglia, Francesca; Moè, Angelica

2013-11-01

In inspecting, learning and reproducing a map, a wide range of abilities is potentially involved. This study examined the role of mental rotation (MR) and verbal ability, together with that of cognitive styles in map learning. As regards cognitive styles, the traditional distinction between verbalizers and visualizers has been taken into account, together with a more recent distinction between two styles of visualization: spatial and object. One hundred and seven participants filled in two questionnaires on cognitive styles: the Verbalizer-Visualizer Questionnaire (Richardson in J Ment Imag 1:109-125, 1977) and the Object-Spatial Imagery Questionnaire (Blajenkova et al. in Appl Cogn Psych 20:239-263, 2006), performed MR and verbal tests, learned two maps, and were then tested for their recall. It was found that MR ability and cognitive styles played a role in predicting map learning, with some distinctions within cognitive styles: verbal style favoured learning of one of the two maps (the one rich in verbal labels), which in turn was disadvantaged by the adoption of spatial style. Conversely, spatial style predicted learning of the other map, rich in visual features. The discussion focuses on implications for cognitive psychology and everyday cognition.

A Computational Model of Afterimage Rotation in the Peripheral Drift Illusion Based on Retinal ON/OFF Responses

PubMed Central

Hayashi, Yuichiro; Ishii, Shin; Urakubo, Hidetoshi

2014-01-01

Human observers perceive illusory rotations after the disappearance of circularly repeating patches containing dark-to-light luminance. This afterimage rotation is a very powerful phenomenon, but little is known about the mechanisms underlying it. Here, we use a computational model to show that the afterimage rotation can be explained by a combination of fast light adaptation and the physiological architecture of the early visual system, consisting of ON- and OFF-type visual pathways. In this retinal ON/OFF model, the afterimage rotation appeared as a rotation of focus lines of retinal ON/OFF responses. Focus lines rotated clockwise on a light background, but counterclockwise on a dark background. These findings were consistent with the results of psychophysical experiments, which were also performed by us. Additionally, the velocity of the afterimage rotation was comparable with that observed in our psychophysical experiments. These results suggest that the early visual system (including the retina) is responsible for the generation of the afterimage rotation, and that this illusory rotation may be systematically misinterpreted by our high-level visual system. PMID:25517906

Influence of Visual Motion, Suggestion, and Illusory Motion on Self-Motion Perception in the Horizontal Plane.

PubMed

Rosenblatt, Steven David; Crane, Benjamin Thomas

2015-01-01

A moving visual field can induce the feeling of self-motion or vection. Illusory motion from static repeated asymmetric patterns creates a compelling visual motion stimulus, but it is unclear if such illusory motion can induce a feeling of self-motion or alter self-motion perception. In these experiments, human subjects reported the perceived direction of self-motion for sway translation and yaw rotation at the end of a period of viewing set visual stimuli coordinated with varying inertial stimuli. This tested the hypothesis that illusory visual motion would influence self-motion perception in the horizontal plane. Trials were arranged into 5 blocks based on stimulus type: moving star field with yaw rotation, moving star field with sway translation, illusory motion with yaw, illusory motion with sway, and static arrows with sway. Static arrows were used to evaluate the effect of cognitive suggestion on self-motion perception. Each trial had a control condition; the illusory motion controls were altered versions of the experimental image, which removed the illusory motion effect. For the moving visual stimulus, controls were carried out in a dark room. With the arrow visual stimulus, controls were a gray screen. In blocks containing a visual stimulus there was an 8s viewing interval with the inertial stimulus occurring over the final 1s. This allowed measurement of the visual illusion perception using objective methods. When no visual stimulus was present, only the 1s motion stimulus was presented. Eight women and five men (mean age 37) participated. To assess for a shift in self-motion perception, the effect of each visual stimulus on the self-motion stimulus (cm/s) at which subjects were equally likely to report motion in either direction was measured. Significant effects were seen for moving star fields for both translation (p = 0.001) and rotation (p<0.001), and arrows (p = 0.02). For the visual motion stimuli, inertial motion perception was shifted in the direction consistent with the visual stimulus. Arrows had a small effect on self-motion perception driven by a minority of subjects. There was no significant effect of illusory motion on self-motion perception for either translation or rotation (p>0.1 for both). Thus, although a true moving visual field can induce self-motion, results of this study show that illusory motion does not.

Synergic effects of 10°/s constant rotation and rotating background on visual cognitive processing

NASA Astrophysics Data System (ADS)

He, Siyang; Cao, Yi; Zhao, Qi; Tan, Cheng; Niu, Dongbin

In previous studies we have found that constant low-speed rotation facilitated the auditory cognitive process and constant velocity rotation background sped up the perception, recognition and assessment process of visual stimuli. In the condition of constant low-speed rotation body is exposed into a new physical state. In this study the variations of human brain's cognitive process under the complex condition of constant low-speed rotation and visual rotation backgrounds with different speed were explored. 14 university students participated in the ex-periment. EEG signals were recorded when they were performing three different cognitive tasks with increasing mental load, that is no response task, selective switch responses task and selec-tive mental arithmetic task. Rotary chair was used to create constant low-speed10/srotation. Four kinds of background were used in this experiment, they were normal black background and constant 30o /s, 45o /s or 60o /s rotating simulated star background. The P1 and N1 compo-nents of brain event-related potentials (ERP) were analyzed to detect the early visual cognitive processing changes. It was found that compared with task performed under other backgrounds, the posterior P1 and N1 latencies were shortened under 45o /s rotating background in all kinds of cognitive tasks. In the no response task, compared with task performed under black back-ground, the posterior N1 latencies were delayed under 30o /s rotating background. In the selec-tive switch responses task and selective mental arithmetic task, compared with task performed under other background, the P1 latencies were lengthened under 60o /s rotating background, but the average amplitudes of the posterior P1 and N1 were increased. It was suggested that under constant 10/s rotation, the facilitated effect of rotating visual background were changed to an inhibited one in 30o /s rotating background. Under vestibular new environment, not all of the rotating backgrounds accelerated the early process of visual cognition. There is a synergic effect between the effects of constant low-speed rotation and rotating speed of the background. Under certain conditions, they both served to facilitate the visual cognitive processing, and it had been started at the stage when extrastriate cortex perceiving the visual signal. Under the condition of constant low-speed rotation in higher cognitive load tasks, the rapid rotation of the background enhanced the magnitude of the signal transmission in the visual path, making signal to noise ratio increased and a higher signal to noise ratio is clearly in favor of target perception and recognition. This gave rise to the hypothesis that higher cognitive load tasks with higher top-down control had more power in counteracting the inhibition effect of higher velocity rotation background. Acknowledgements: This project was supported by National Natural Science Foundation of China (No. 30670715) and National High Technology Research and Development Program of China (No.2007AA04Z254).

Visual perception of axes of head rotation

PubMed Central

Arnoldussen, D. M.; Goossens, J.; van den Berg, A. V.

2013-01-01

Registration of ego-motion is important to accurately navigate through space. Movements of the head and eye relative to space are registered through the vestibular system and optical flow, respectively. Here, we address three questions concerning the visual registration of self-rotation. (1) Eye-in-head movements provide a link between the motion signals received by sensors in the moving eye and sensors in the moving head. How are these signals combined into an ego-rotation percept? We combined optic flow of simulated forward and rotational motion of the eye with different levels of eye-in-head rotation for a stationary head. We dissociated simulated gaze rotation and head rotation by different levels of eye-in-head pursuit. We found that perceived rotation matches simulated head- not gaze-rotation. This rejects a model for perceived self-rotation that relies on the rotation of the gaze line. Rather, eye-in-head signals serve to transform the optic flow's rotation information, that specifies rotation of the scene relative to the eye, into a rotation relative to the head. This suggests that transformed visual self-rotation signals may combine with vestibular signals. (2) Do transformed visual self-rotation signals reflect the arrangement of the semi-circular canals (SCC)? Previously, we found sub-regions within MST and V6+ that respond to the speed of the simulated head rotation. Here, we re-analyzed those Blood oxygenated level-dependent (BOLD) signals for the presence of a spatial dissociation related to the axes of visually simulated head rotation, such as have been found in sub-cortical regions of various animals. Contrary, we found a rather uniform BOLD response to simulated rotation along the three SCC axes. (3) We investigated if subject's sensitivity to the direction of the head rotation axis shows SCC axes specifcity. We found that sensitivity to head rotation is rather uniformly distributed, suggesting that in human cortex, visuo-vestibular integration is not arranged into the SCC frame. PMID:23919087

Horizontal visual search in a large field by patients with unilateral spatial neglect.

PubMed

Nakatani, Ken; Notoya, Masako; Sunahara, Nobuyuki; Takahashi, Shusuke; Inoue, Katsumi

2013-06-01

In this study, we investigated the horizontal visual search ability and pattern of horizontal visual search in a large space performed by patients with unilateral spatial neglect (USN). Subjects included nine patients with right hemisphere damage caused by cerebrovascular disease showing left USN, nine patients with right hemisphere damage but no USN, and six healthy individuals with no history of brain damage who were age-matched to the groups with brain right hemisphere damage. The number of visual search tasks accomplished was recorded in the first experiment. Neck rotation angle was continuously measured during the task and quantitative data of the measurements were collected. There was a strong correlation between the number of visual search tasks accomplished and the total Behavioral Inattention Test Conventional Subtest (BITC) score in subjects with right hemisphere damage. In both USN and control groups, the head position during the visual search task showed a balanced bell-shaped distribution from the central point on the field to the left and right sides. Our results indicate that compensatory strategies, including cervical rotation, may improve visual search capability and achieve balance on the neglected side. Copyright © 2012 Elsevier Ltd. All rights reserved.

Holographic flow visualization in rotating turbomachinery

NASA Astrophysics Data System (ADS)

Parker, R. J.; Reeves, M.

1990-11-01

Holographic flow visualization has found many applications in rotating turbomachinery. Applications in the design of aeroengine fans, automotive turbochargers, turbines, helicopter rotors, and advanced propfans are discussed. Work in ducted rotating flows and rotating free aerofoils is brought together and new developments in each field are revealed.

Genetic and Environmental Influences on the Verbal-Perceptual-Image Rotation (VPR) Model of the Structure of Mental Abilities in the Minnesota Study of Twins Reared Apart

ERIC Educational Resources Information Center

Johnson, Wendy; Bouchard, Thomas J.; McGue, Matt; Segal, Nancy L.; Tellegen, Auke; Keyes, Margaret; Gottesman, Irving I.

2007-01-01

In previous papers [Johnson, W., & Bouchard Jr., T. J. (2005a). Constructive Replication of the Visual-Perceptual-Image Rotation (VPR) Model in Thurstone's (1941) Battery of 60 Tests of Mental Ability. Intelligence, 33, 417-430.] [Johnson, W., & Bouchard Jr., T. J. (2005b). The Structure of Human Intelligence: It's Verbal, perceptual, and image…

Slow changing postural cues cancel visual field dependence on self-tilt detection.

PubMed

Scotto Di Cesare, C; Macaluso, T; Mestre, D R; Bringoux, L

2015-01-01

Interindividual differences influence the multisensory integration process involved in spatial perception. Here, we assessed the effect of visual field dependence on self-tilt detection relative to upright, as a function of static vs. slow changing visual or postural cues. To that aim, we manipulated slow rotations (i.e., 0.05° s(-1)) of the body and/or the visual scene in pitch. Participants had to indicate whether they felt being tilted forward at successive angles. Results show that thresholds for self-tilt detection substantially differed between visual field dependent/independent subjects, when only the visual scene was rotated. This difference was no longer present when the body was actually rotated, whatever the visual scene condition (i.e., absent, static or rotated relative to the observer). These results suggest that the cancellation of visual field dependence by dynamic postural cues may rely on a multisensory reweighting process, where slow changing vestibular/somatosensory inputs may prevail over visual inputs. Copyright © 2014 Elsevier B.V. All rights reserved.

Incidence of foot rotation, pelvic crest unleveling, and supine leg length alignment asymmetry and their relationship to self-reported back pain.

PubMed

Knutson, Gary A

2002-02-01

To determine the incidence of pelvic unleveling, foot rotation, and supine leg length alignment asymmetry in a nonclinical population and to examine the validity (sensitivity, specificity, positive and negative predictive values) of these visual tests and their relationship to self-reported back pain. Volunteers answered a questionnaire regarding back pain and were then examined by a chiropractor who was unaware of the status of their back pain. Seventy-four unscreened volunteers answered the questionnaire. The association of visual tests with back pain and their validity indices; Visual Analogue Scale ratings. Fifty-one percent (n = 74) of volunteers examined had supine leg length alignment asymmetry (LLA). Pain intensity on a Visual Analogue Scale was significantly higher (P <.001) for those demonstrating supine LLA than for those without LLA. Those with back pain and recurrent back pain were significantly (P <.001) more likely to have supine LLA. The validity indices of the supine leg check showed acceptable levels for sensitivity (74%), specificity (78%), and positive predictive value (82%) [corrected] in recurrent back pain. Findings also indicated a high incidence of supine LLA in volunteers with chronic back pain (85%). The results indicated that, in this group of volunteers, the supine leg length alignment check had clinical validity as a stand-alone test for recurring back pain. Further testing on a larger, statistically defined cross-section of the population is recommended.

A novel role for visual perspective cues in the neural computation of depth.

PubMed

Kim, HyungGoo R; Angelaki, Dora E; DeAngelis, Gregory C

2015-01-01

As we explore a scene, our eye movements add global patterns of motion to the retinal image, complicating visual motion produced by self-motion or moving objects. Conventionally, it has been assumed that extraretinal signals, such as efference copy of smooth pursuit commands, are required to compensate for the visual consequences of eye rotations. We consider an alternative possibility: namely, that the visual system can infer eye rotations from global patterns of image motion. We visually simulated combinations of eye translation and rotation, including perspective distortions that change dynamically over time. We found that incorporating these 'dynamic perspective' cues allowed the visual system to generate selectivity for depth sign from motion parallax in macaque cortical area MT, a computation that was previously thought to require extraretinal signals regarding eye velocity. Our findings suggest neural mechanisms that analyze global patterns of visual motion to perform computations that require knowledge of eye rotations.

Estimation of detection thresholds for redirected walking techniques.

PubMed

Steinicke, Frank; Bruder, Gerd; Jerald, Jason; Frenz, Harald; Lappe, Markus

2010-01-01

In immersive virtual environments (IVEs), users can control their virtual viewpoint by moving their tracked head and walking through the real world. Usually, movements in the real world are mapped one-to-one to virtual camera motions. With redirection techniques, the virtual camera is manipulated by applying gains to user motion so that the virtual world moves differently than the real world. Thus, users can walk through large-scale IVEs while physically remaining in a reasonably small workspace. In psychophysical experiments with a two-alternative forced-choice task, we have quantified how much humans can unknowingly be redirected on physical paths that are different from the visually perceived paths. We tested 12 subjects in three different experiments: (E1) discrimination between virtual and physical rotations, (E2) discrimination between virtual and physical straightforward movements, and (E3) discrimination of path curvature. In experiment E1, subjects performed rotations with different gains, and then had to choose whether the visually perceived rotation was smaller or greater than the physical rotation. In experiment E2, subjects chose whether the physical walk was shorter or longer than the visually perceived scaled travel distance. In experiment E3, subjects estimate the path curvature when walking a curved path in the real world while the visual display shows a straight path in the virtual world. Our results show that users can be turned physically about 49 percent more or 20 percent less than the perceived virtual rotation, distances can be downscaled by 14 percent and upscaled by 26 percent, and users can be redirected on a circular arc with a radius greater than 22 m while they believe that they are walking straight.

Updating of visual orientation in a gravity-based reference frame.

PubMed

Niehof, Nynke; Tramper, Julian J; Doeller, Christian F; Medendorp, W Pieter

2017-10-01

The brain can use multiple reference frames to code line orientation, including head-, object-, and gravity-centered references. If these frames change orientation, their representations must be updated to keep register with actual line orientation. We tested this internal updating during head rotation in roll, exploiting the rod-and-frame effect: The illusory tilt of a vertical line surrounded by a tilted visual frame. If line orientation is stored relative to gravity, these distortions should also affect the updating process. Alternatively, if coding is head- or frame-centered, updating errors should be related to the changes in their orientation. Ten subjects were instructed to memorize the orientation of a briefly flashed line, surrounded by a tilted visual frame, then rotate their head, and subsequently judge the orientation of a second line relative to the memorized first while the frame was upright. Results showed that updating errors were mostly related to the amount of subjective distortion of gravity at both the initial and final head orientation, rather than to the amount of intervening head rotation. In some subjects, a smaller part of the updating error was also related to the change of visual frame orientation. We conclude that the brain relies primarily on a gravity-based reference to remember line orientation during head roll.

Visualizing Compound Rotations with Virtual Reality

ERIC Educational Resources Information Center

Flanders, Megan; Kavanagh, Richard C.

2013-01-01

Mental rotations are among the most difficult of all spatial tasks to perform, and even those with high levels of spatial ability can struggle to visualize the result of compound rotations. This pilot study investigates the use of the virtual reality-based Rotation Tool, created using the Virtual Reality Modeling Language (VRML) together with…

Spherical Coordinate Systems for Streamlining Suited Mobility Analysis

NASA Technical Reports Server (NTRS)

Benson, Elizabeth; Cowley, Matthew S.; Harvill. Lauren; Rajulu, Sudhakar

2014-01-01

When describing human motion, biomechanists generally report joint angles in terms of Euler angle rotation sequences. However, there are known limitations in using this method to describe complex motions such as the shoulder joint during a baseball pitch. Euler angle notation uses a series of three rotations about an axis where each rotation is dependent upon the preceding rotation. As such, the Euler angles need to be regarded as a set to get accurate angle information. Unfortunately, it is often difficult to visualize and understand these complex motion representations. One of our key functions is to help design engineers understand how a human will perform with new designs and all too often traditional use of Euler rotations becomes as much of a hindrance as a help. It is believed that using a spherical coordinate system will allow ABF personnel to more quickly and easily transmit important mobility data to engineers, in a format that is readily understandable and directly translatable to their design efforts. Objectives: The goal of this project is to establish new analysis and visualization techniques to aid in the examination and comprehension of complex motions. Methods: This project consisted of a series of small sub-projects, meant to validate and verify the method before it was implemented in the ABF's data analysis practices. The first stage was a proof of concept, where a mechanical test rig was built and instrumented with an inclinometer, so that its angle from horizontal was known. The test rig was tracked in 3D using an optical motion capture system, and its position and orientation were reported in both Euler and spherical reference systems. The rig was meant to simulate flexion/extension, transverse rotation and abduction/adduction of the human shoulder, but without the variability inherent in human motion. In the second phase of the project, the ABF estimated the error inherent in a spherical coordinate system, and evaluated how this error would vary within the reference frame. This stage also involved expanding a kinematic model of the shoulder, to include the torso, knees, ankle, elbows, wrists and neck. Part of this update included adding a representation of 'roll' about an axis, for upper arm and lower leg rotations. The third stage of the project involved creating visualization methods to assist in interpreting motion in a spherical frame. This visualization method will be incorporated in a tool to evaluate a database of suited mobility data, which is currently in development.

Spatial and Visual Reasoning: Do These Abilities Improve in First-Year Veterinary Medical Students Exposed to an Integrated Curriculum?

PubMed

Gutierrez, J Claudio; Chigerwe, Munashe; Ilkiw, Jan E; Youngblood, Patricia; Holladay, Steven D; Srivastava, Sakti

Spatial visualization ability refers to the human cognitive ability to form, retrieve, and manipulate mental models of spatial nature. Visual reasoning ability has been linked to spatial ability. There is currently limited information about how entry-level spatial and visual reasoning abilities may predict veterinary anatomy performance or may be enhanced with progression through the veterinary anatomy content in an integrated curriculum. The present study made use of two tests that measure spatial ability and one test that measures visual reasoning ability in veterinary students: Guay's Visualization of Views Test, adapted version (GVVT), the Mental Rotations Test (MRT), and Raven's Advanced Progressive Matrices Test, short form (RavenT). The tests were given to the entering class of veterinary students during their orientation week and at week 32 in the veterinary medical curriculum. Mean score on the MRT significantly increased from 15.2 to 20.1, and on the RavenT significantly increased from 7.5 to 8.8. When females only were evaluated, results were similar to the total class outcome; however, all three tests showed significant increases in mean scores. A positive correlation between the pre- and post-test scores was found for all three tests. The present results should be considered preliminary at best for associating anatomic learning in an integrated curriculum with spatial and visual reasoning abilities. Other components of the curriculum, for instance histology or physiology, could also influence the improved spatial visualization and visual reasoning test scores at week 32.

A novel role for visual perspective cues in the neural computation of depth

PubMed Central

Kim, HyungGoo R.; Angelaki, Dora E.; DeAngelis, Gregory C.

2014-01-01

As we explore a scene, our eye movements add global patterns of motion to the retinal image, complicating visual motion produced by self-motion or moving objects. Conventionally, it has been assumed that extra-retinal signals, such as efference copy of smooth pursuit commands, are required to compensate for the visual consequences of eye rotations. We consider an alternative possibility: namely, that the visual system can infer eye rotations from global patterns of image motion. We visually simulated combinations of eye translation and rotation, including perspective distortions that change dynamically over time. We demonstrate that incorporating these “dynamic perspective” cues allows the visual system to generate selectivity for depth sign from motion parallax in macaque area MT, a computation that was previously thought to require extra-retinal signals regarding eye velocity. Our findings suggest novel neural mechanisms that analyze global patterns of visual motion to perform computations that require knowledge of eye rotations. PMID:25436667

Characteristics of moving visual scenes influencing spatial orientation

NASA Technical Reports Server (NTRS)

Held, R.; Bauer, J.; Dichgans, J.

1975-01-01

A visual display rotating in a frontal plane induces effects equivalent to a change in the apparent direction of gravity. Magnitude of visual tilt was measured as a function of time from onset of rotation, velocity of rotation, and area and retinal location of the stimulating field. The mejor part of the tilt occurs within 30 sec from onset of stimulation. It increases with angular velocity, but independently of area and location of field, up to about 30 to 40 deg of rotation per sec and then levels off. Tilt increases with field size but the effect of thin ring-fields increases with retinal eccentricity. The interaction of visual and nonvisual determinants of the induced effects is discussed.

Visually induced self-motion sensation adapts rapidly to left-right reversal of vision

NASA Technical Reports Server (NTRS)

Oman, C. M.; Bock, O. L.

1981-01-01

Three experiments were conducted using 15 adult volunteers with no overt oculomotor or vestibular disorders. In all experiments, left-right vision reversal was achieved using prism goggles, which permitted a binocular field of vision subtending approximately 45 deg horizontally and 28 deg vertically. In all experiments, circularvection (CV) was tested before and immediately after a period of exposure to reversed vision. After one to three hours of active movement while wearing vision-reversing goggles, 10 of 15 (stationary) human subjects viewing a moving stripe display experienced a self-rotation illusion in the same direction as seen stripe motion, rather than in the opposite (normal) direction, demonstrating that the central neural pathways that process visual self-rotation cues can undergo rapid adaptive modification.

Breaking new ground in the mind: an initial study of mental brittle transformation and mental rigid rotation in science experts.

PubMed

Resnick, Ilyse; Shipley, Thomas F

2013-05-01

The current study examines the spatial skills employed in different spatial reasoning tasks, by asking how science experts who are practiced in different types of visualizations perform on different spatial tasks. Specifically, the current study examines the varieties of mental transformations. We hypothesize that there may be two broad classes of mental transformations: rigid body mental transformations and non-rigid mental transformations. We focus on the disciplines of geology and organic chemistry because different types of transformations are central to the two disciplines: While geologists and organic chemists may both confront rotation in the practice of their profession, only geologists confront brittle transformations. A new instrument was developed to measure mental brittle transformation (visualizing breaking). Geologists and organic chemists performed similarly on a measure of mental rotation, while geologists outperformed organic chemists on the mental brittle transformation test. The differential pattern of skill on the two tests for the two groups of experts suggests that mental brittle transformation and mental rotation are different spatial skills. The roles of domain general cognitive resources (attentional control, spatial working memory, and perceptual filling in) and strategy in completing mental brittle transformation are discussed. The current study illustrates how ecological and interdisciplinary approaches complement traditional cognitive science to offer a comprehensive approach to understanding the nature of spatial thinking.

Three-dimensional organization of vestibular-related eye movements to off-vertical axis rotation and linear translation in pigeons

NASA Technical Reports Server (NTRS)

Dickman, J. D.; Angelaki, D. E.

1999-01-01

During linear accelerations, compensatory reflexes should continually occur in order to maintain objects of visual interest as stable images on the retina. In the present study, the three-dimensional organization of the vestibulo-ocular reflex in pigeons was quantitatively examined during linear accelerations produced by constant velocity off-vertical axis yaw rotations and translational motion in darkness. With off-vertical axis rotations, sinusoidally modulated eye-position and velocity responses were observed in all three components, with the vertical and torsional eye movements predominating the response. Peak torsional and vertical eye positions occurred when the head was oriented with the lateral visual axis of the right eye directed orthogonal to or aligned with the gravity vector, respectively. No steady-state horizontal nystagmus was obtained with any of the rotational velocities (8-58 degrees /s) tested. During translational motion, delivered along or perpendicular to the lateral visual axis, vertical and torsional eye movements were elicited. No significant horizontal eye movements were observed during lateral translation at frequencies up to 3 Hz. These responses suggest that, in pigeons, all linear accelerations generate eye movements that are compensatory to the direction of actual or perceived tilt of the head relative to gravity. In contrast, no translational horizontal eye movements, which are known to be compensatory to lateral translational motion in primates, were observed under the present experimental conditions.

Phantom motion after effects--evidence of detectors for the analysis of optic flow.

PubMed

Snowden, R J; Milne, A B

1997-10-01

Electrophysiological recording from the extrastriate cortex of non-human primates has revealed neurons that have large receptive fields and are sensitive to various components of object or self movement, such as translations, rotations and expansion/contractions. If these mechanisms exist in human vision, they might be susceptible to adaptation that generates motion aftereffects (MAEs). Indeed, it might be possible to adapt the mechanism in one part of the visual field and reveal what we term a 'phantom MAE' in another part. The existence of phantom MAEs was probed by adapting to a pattern that contained motion in only two non-adjacent 'quarter' segments and then testing using patterns that had elements in only the other two segments. We also tested for the more conventional 'concrete' MAE by testing in the same two segments that had adapted. The strength of each MAE was quantified by measuring the percentage of dots that had to be moved in the opposite direction to the MAE in order to nullify it. Four experiments tested rotational motion, expansion/contraction motion, translational motion and a 'rotation' that consisted simply of the two segments that contained only translational motions of opposing direction. Compared to a baseline measurement where no adaptation took place, all subjects in all experiments exhibited both concrete and phantom MAEs, with the size of the latter approximately half that of the former. Adaptation to two segments that contained upward and downward motion induced the perception of leftward and rightward motion in another part of the visual field. This strongly suggests there are mechanisms in human vision that are sensitive to complex motions such as rotations.

General principles in motion vision: color blindness of object motion depends on pattern velocity in honeybee and goldfish.

PubMed

Stojcev, Maja; Radtke, Nils; D'Amaro, Daniele; Dyer, Adrian G; Neumeyer, Christa

2011-07-01

Visual systems can undergo striking adaptations to specific visual environments during evolution, but they can also be very "conservative." This seems to be the case in motion vision, which is surprisingly similar in species as distant as honeybee and goldfish. In both visual systems, motion vision measured with the optomotor response is color blind and mediated by one photoreceptor type only. Here, we ask whether this is also the case if the moving stimulus is restricted to a small part of the visual field, and test what influence velocity may have on chromatic motion perception. Honeybees were trained to discriminate between clockwise- and counterclockwise-rotating sector disks. Six types of disk stimuli differing in green receptor contrast were tested using three different rotational velocities. When green receptor contrast was at a minimum, bees were able to discriminate rotation directions with all colored disks at slow velocities of 6 and 12 Hz contrast frequency but not with a relatively high velocity of 24 Hz. In the goldfish experiment, the animals were trained to detect a moving red or blue disk presented in a green surround. Discrimination ability between this stimulus and a homogenous green background was poor when the M-cone type was not or only slightly modulated considering high stimulus velocity (7 cm/s). However, discrimination was improved with slower stimulus velocities (4 and 2 cm/s). These behavioral results indicate that there is potentially an object motion system in both honeybee and goldfish, which is able to incorporate color information at relatively low velocities but is color blind with higher speed. We thus propose that both honeybees and goldfish have multiple subsystems of object motion, which include achromatic as well as chromatic processing.

Fear improves mental rotation of low-spatial-frequency visual representation.

PubMed

Borst, Grégoire

2013-10-01

Previous studies have demonstrated that the brief presentation of a fearful face improves not only low-level visual processing such as contrast and orientation sensitivity but also improves visuospatial processing. In the present study, we investigated whether fear improves mental rotation efficiency (i.e., the mental rotation rate) because of the effect of fear on the sensitivity of magnocellular neurons. We asked 2 groups of participants to perform a mental rotation task with either low-pass or high-pass filtered 3-dimensional objects. Following the presentation of a fearful face, participants mentally rotated objects faster compared with when a neutral face was presented but only for low-pass filtered objects. The results suggest that fear improves mental rotation efficiency by increasing sensitivity to motion-related visual information within the magnocellular pathway.

Validity of eyeball estimation for range of motion during the cervical flexion rotation test compared to an ultrasound-based movement analysis system.

PubMed

Schäfer, Axel; Lüdtke, Kerstin; Breuel, Franziska; Gerloff, Nikolas; Knust, Maren; Kollitsch, Christian; Laukart, Alex; Matej, Laura; Müller, Antje; Schöttker-Königer, Thomas; Hall, Toby

2018-08-01

Headache is a common and costly health problem. Although pathogenesis of headache is heterogeneous, one reported contributing factor is dysfunction of the upper cervical spine. The flexion rotation test (FRT) is a commonly used diagnostic test to detect upper cervical movement impairment. The aim of this cross-sectional study was to investigate concurrent validity of detecting high cervical ROM impairment during the FRT by comparing measurements established by an ultrasound-based system (gold standard) with eyeball estimation. Secondary aim was to investigate intra-rater reliability of FRT ROM eyeball estimation. The examiner (6 years experience) was blinded to the data from the ultrasound-based device and to the symptoms of the patients. FRT test result (positive or negative) was based on visual estimation of range of rotation less than 34° to either side. Concurrently, range of rotation was evaluated using the ultrasound-based device. A total of 43 subjects with headache (79% female), mean age of 35.05 years (SD 13.26) were included. According to the International Headache Society Classification 23 subjects had migraine, 4 tension type headache, and 16 multiple headache forms. Sensitivity and specificity were 0.96 and 0.89 for combined rotation, indicating good concurrent reliability. The area under the ROC curve was 0.95 (95% CI 0.91-0.98) for rotation to both sides. Intra-rater reliability for eyeball estimation was excellent with Fleiss Kappa 0.79 for right rotation and left rotation. The results of this study indicate that the FRT is a valid and reliable test to detect impairment of upper cervical ROM in patients with headache.

Deficiency in Mental Rotation of Upper and Lower-Limbs in Patients With Multiple Sclerosis and Its Relation With Cognitive Functions.

PubMed

Azin, Mahdieh; Zangiabadi, Nasser; Moghadas Tabrizi, Yousef; Iranmanesh, Farhad; Baneshi, Mohammad Reza

2016-08-01

Mental rotation is a cognitive motor process which was impaired in different neurologic disorders. We investigated whether there were deficits in response pattern, reaction time and response accuracy rate of mental rotation in multiple sclerosis (MS) patients compared to healthy subjects and whether cognitive dysfunctions in MS patients were correlated with mental rotation deficits. Moreover, we showed whether there was a difference between upper and lower-limbs mental rotation in MS patients. Thirty-five MS patients and 25 healthy subjects performed hand mental rotation (HMR) and foot mental rotation (FMR) tasks. Visual information processing speed, spatial learning and memory ability, and visuospatial processing were assessed by Symbol Digit Modalities Test (SDMT), Brief Visuospatial Memory Test-Revised (BVMT-R), and Judgment of Line Orientation Test (JLO) respectively in MS patients. Reaction time for both hand and foot stimuli increased, and response accuracy rate for hand stimuli decreased in MS patients compared to healthy subjects, but response pattern of mental rotation in MS patients persisted. Similar to healthy subjects, MS patients performed upper-limbs mental rotation more easily than a lower-limbs mental rotation with more speed and response accuracy rate. Reaction time and response accuracy rate were correlated with the mentioned cognitive functions. MS patients made use of the correct response pattern for problem solving of increasing orientation from upright stimuli. Reaction time and response accuracy rate altered in these patients and this alteration might occur along with impairment in motor planning. Subjects' better responding to hand stimuli was due to more familiarity with hand stimuli. The correlation of mental rotation ability with cognitive functions indicates the possible role of cognitive functions in mental rotation.

Capacity for visual features in mental rotation

PubMed Central

Xu, Yangqing; Franconeri, Steven L.

2015-01-01

Although mental rotation is a core component of scientific reasoning, we still know little about its underlying mechanism. For instance - how much visual information can we rotate at once? Participants rotated a simple multi-part shape, requiring them to maintain attachments between features and moving parts. The capacity of this aspect of mental rotation was strikingly low – only one feature could remain attached to one part. Behavioral and eyetracking data showed that this single feature remained ‘glued’ via a singular focus of attention, typically on the object’s top. We argue that the architecture of the human visual system is not suited for keeping multiple features attached to multiple parts during mental rotation. Such measurement of the capacity limits may prove to be a critical step in dissecting the suite of visuospatial tools involved in mental rotation, leading to insights for improvement of pedagogy in science education contexts. PMID:26174781

Capacity for Visual Features in Mental Rotation.

PubMed

Xu, Yangqing; Franconeri, Steven L

2015-08-01

Although mental rotation is a core component of scientific reasoning, little is known about its underlying mechanisms. For instance, how much visual information can someone rotate at once? We asked participants to rotate a simple multipart shape, requiring them to maintain attachments between features and moving parts. The capacity of this aspect of mental rotation was strikingly low: Only one feature could remain attached to one part. Behavioral and eye-tracking data showed that this single feature remained "glued" via a singular focus of attention, typically on the object's top. We argue that the architecture of the human visual system is not suited for keeping multiple features attached to multiple parts during mental rotation. Such measurement of capacity limits may prove to be a critical step in dissecting the suite of visuospatial tools involved in mental rotation, leading to insights for improvement of pedagogy in science-education contexts. © The Author(s) 2015.

Contributions to workload of rotational optical transformations

NASA Technical Reports Server (NTRS)

Atkinson, R. P.; Harrington, T. L.

1985-01-01

An investigation of visuomotor adaptation to optical rotation and optical inversion was conducted. Experiment 1 examined the visuomotor adaptability of subjects to an optically rotating visual world with a univariate repeated measures design. Experiment 1A tested one major prediction of a model of adaptation put forth by Welch who predicted that the aversive drive state that triggers adaptation would be habituated to fairly rapidly. Experiment 2 was conducted to investigate the role of motor activity in adaptation to optical rotation. Specifically, this experiment contrasted the reafference hypothesis and the proprioceptive change hypothesis. Experiment 3 examined the role of cognition, error-corrective feedback, and proprioceptive and/or reafferent feedback in visuomotor adaptation to optical inversion. Implications for research and implications for practice were suggested for all experiments.

Rotational dynamics of cargos at pauses during axonal transport.

PubMed

Gu, Yan; Sun, Wei; Wang, Gufeng; Jeftinija, Ksenija; Jeftinija, Srdija; Fang, Ning

2012-01-01

Direct visualization of axonal transport in live neurons is essential for our understanding of the neuronal functions and the working mechanisms of microtubule-based motor proteins. Here we use the high-speed single particle orientation and rotational tracking technique to directly visualize the rotational dynamics of cargos in both active directional transport and pausing stages of axonal transport, with a temporal resolution of 2 ms. Both long and short pauses are imaged, and the correlations between the pause duration, the rotational behaviour of the cargo at the pause, and the moving direction after the pause are established. Furthermore, the rotational dynamics leading to switching tracks are visualized in detail. These first-time observations of cargo's rotational dynamics provide new insights on how kinesin and dynein motors take the cargo through the alternating stages of active directional transport and pause.

[Visual and motor functions in schizophrenic patients].

PubMed

Del Vecchio, S; Gargiulo, P A

1992-12-01

In the present work, visual and motor functions have been explored in 26 chronic schizophrenic patients, and 7 acute schizophrenic patients, compared with 26 normal controls, by means of the Bender-Gestalt Test. Parameters under consideration were: Form distortion, rotation, integration, perseveration, use of space, subtle motricity, score (global parameter), and time employed. As regards distortion and rotation there have been highly significant differences between chronic patients and control group. Among acute patients, it was observed that perseveration was also highly significant. Conversely, integration and use of space did not differ significantly among the three groups involved. The global score, resulting from all the above mentioned parameters showed important differences between both patient groups on the one hand, and control group on the other hand. Taking into account that patients were being administered neuroleptic drugs, it can safely be said, however, that the Bender-Gestalt Test allows to recognize alteration in perceptual closure consistent with a loss of the objective structure of perceived phenomena, in both chronic and acute patients.

Pictorial Visual Rotation Ability of Engineering Design Graphics Students

ERIC Educational Resources Information Center

Ernst, Jeremy Vaughn; Lane, Diarmaid; Clark, Aaron C.

2015-01-01

The ability to rotate visual mental images is a complex cognitive skill. It requires the building of graphical libraries of information through short or long term memory systems and the subsequent retrieval and manipulation of these towards a specified goal. The development of mental rotation skill is of critical importance within engineering…

Visual Navigation during Colony Emigration by the Ant Temnothorax rugatulus

PubMed Central

Bowens, Sean R.; Glatt, Daniel P.; Pratt, Stephen C.

2013-01-01

Many ants rely on both visual cues and self-generated chemical signals for navigation, but their relative importance varies across species and context. We evaluated the roles of both modalities during colony emigration by Temnothorax rugatulus. Colonies were induced to move from an old nest in the center of an arena to a new nest at the arena edge. In the midst of the emigration the arena floor was rotated 60°around the old nest entrance, thus displacing any substrate-bound odor cues while leaving visual cues unchanged. This manipulation had no effect on orientation, suggesting little influence of substrate cues on navigation. When this rotation was accompanied by the blocking of most visual cues, the ants became highly disoriented, suggesting that they did not fall back on substrate cues even when deprived of visual information. Finally, when the substrate was left in place but the visual surround was rotated, the ants' subsequent headings were strongly rotated in the same direction, showing a clear role for visual navigation. Combined with earlier studies, these results suggest that chemical signals deposited by Temnothorax ants serve more for marking of familiar territory than for orientation. The ants instead navigate visually, showing the importance of this modality even for species with small eyes and coarse visual acuity. PMID:23671713

A qualitative inquiry into the effects of visualization on high school chemistry students' learning process of molecular structure

NASA Astrophysics Data System (ADS)

Deratzou, Susan

This research studies the process of high school chemistry students visualizing chemical structures and its role in learning chemical bonding and molecular structure. Minimal research exists with high school chemistry students and more research is necessary (Gabel & Sherwood, 1980; Seddon & Moore, 1986; Seddon, Tariq, & Dos Santos Veiga, 1984). Using visualization tests (Ekstrom, French, Harman, & Dermen, 1990a), a learning style inventory (Brown & Cooper, 1999), and observations through a case study design, this study found visual learners performed better, but needed more practice and training. Statistically, all five pre- and post-test visualization test comparisons were highly significant in the two-tailed t-test (p > .01). The research findings are: (1) Students who tested high in the Visual (Language and/or Numerical) and Tactile Learning Styles (and Social Learning) had an advantage. Students who learned the chemistry concepts more effectively were better at visualizing structures and using molecular models to enhance their knowledge. (2) Students showed improvement in learning after visualization practice. Training in visualization would improve students' visualization abilities and provide them with a way to think about these concepts. (3) Conceptualization of concepts indicated that visualizing ability was critical and that it could be acquired. Support for this finding was provided by pre- and post-Visualization Test data with a highly significant t-test. (4) Various molecular animation programs and websites were found to be effective. (5) Visualization and modeling of structures encompassed both two- and three-dimensional space. The Visualization Test findings suggested that the students performed better with basic rotation of structures as compared to two- and three-dimensional objects. (6) Data from observations suggest that teaching style was an important factor in student learning of molecular structure. (7) Students did learn the chemistry concepts. Based on the Visualization Test results, which showed that most of the students performed better on the post-test, the visualization experience and the abstract nature of the content allowed them to transfer some of their chemical understanding and practice to non-chemical structures. Finally, implications for teaching of chemistry, students learning chemistry, curriculum, and research for the field of chemical education were discussed.

Rotary acceleration of a subject inhibits choice reaction time to motion in peripheral vision

NASA Technical Reports Server (NTRS)

Borkenhagen, J. M.

1974-01-01

Twelve pilots were tested in a rotation device with visual simulation, alone and in combination with rotary stimulation, in experiments with variable levels of acceleration and variable viewing angles, in a study of the effect of S's rotary acceleration on the choice reaction time for an accelerating target in peripheral vision. The pilots responded to the direction of the visual motion by moving a hand controller to the right or left. Visual-plus-rotary stimulation required a longer choice reaction time, which was inversely related to the level of acceleration and directly proportional to the viewing angle.

Age-related changes in human posture control: Sensory organization tests

NASA Technical Reports Server (NTRS)

Peterka, R. J.; Black, F. O.

1989-01-01

Postural control was measured in 214 human subjects ranging in age from 7 to 81 years. Sensory organization tests measured the magnitude of anterior-posterior body sway during six 21 s trials in which visual and somatosensory orientation cues were altered (by rotating the visual surround and support surface in proportion to the subject's sway) or vision eliminated (eyes closed) in various combinations. No age-related increase in postural sway was found for subjects standing on a fixed support surface with eyes open or closed. However, age-related increases in sway were found for conditions involving altered visual or somatosensory cues. Subjects older than about 55 years showed the largest sway increases. Subjects younger than about 15 years were also sensitive to alteration of sensory cues. On average, the older subjects were more affected by altered visual cues whereas younger subjects had more difficulty with altered somatosensory cues.

Binocular Coordination of the Human Vestibulo-Ocular Reflex during Off-axis Pitch Rotation

NASA Technical Reports Server (NTRS)

Wood, S. J.; Reschke, M. F.; Kaufman, G. D.; Black, F. O.; Paloski, W. H.

2006-01-01

Head movements in the sagittal pitch plane typically involve off-axis rotation requiring both vertical and horizontal vergence ocular reflexes to compensate for angular and translational motion relative to visual targets of interest. The purpose of this study was to compare passive pitch VOR responses during rotation about an Earth-vertical axis (canal only cues) with off-axis rotation (canal and otolith cues). Methods. Eleven human subjects were oscillated sinusoidally at 0.13, 0.3 and 0.56 Hz while lying left-side down with the interaural axis either aligned with the axis of rotation or offset by 50 cm. In a second set of measurements, twelve subjects were also tested during sinusoidally varying centrifugation over the same frequency range. The modulation of vertical and horizontal vergence ocular responses was measured with a binocular videography system. Results. Off-axis pitch rotation enhanced the vertical VOR at lower frequencies and enhanced the vergence VOR at higher frequencies. During sinusoidally varying centrifugation, the opposite trend was observed for vergence, with both vertical and vergence vestibulo-ocular reflexes being suppressed at the highest frequency. Discussion. These differential effects of off-axis rotation over the 0.13 to 0.56 Hz range are consistent with the hypothesis that otolith-ocular reflexes are segregated in part on the basis of stimulus frequency. At the lower frequencies, tilt otolith-ocular responses compensate for declining canal input. At higher frequencies, translational otolith-ocular reflexes compensate for declining visual contributions to the kinematic demands required for fixating near targets.

Sustained change blindness to incremental scene rotation: a dissociation between explicit change detection and visual memory.

PubMed

Hollingworth, Andrew; Henderson, John M

2004-07-01

In a change detection paradigm, the global orientation of a natural scene was incrementally changed in 1 degree intervals. In Experiments 1 and 2, participants demonstrated sustained change blindness to incremental rotation, often coming to consider a significantly different scene viewpoint as an unchanged continuation of the original view. Experiment 3 showed that participants who failed to detect the incremental rotation nevertheless reliably detected a single-step rotation back to the initial view. Together, these results demonstrate an important dissociation between explicit change detection and visual memory. Following a change, visual memory is updated to reflect the changed state of the environment, even if the change was not detected.

Spatial Abilities across the Adult Life Span

ERIC Educational Resources Information Center

Borella, Erika; Meneghetti, Chiara; Ronconi, Lucia; De Beni, Rossana

2014-01-01

The study investigates age-related effects across the adult life span on spatial abilities (testing subabilities based on a distinction between spatial visualization, mental rotation, and perspective taking) and spatial self-assessments. The sample consisted of 454 participants (223 women and 231 men) from 20 to 91 years of age. Results showed…

Transonic flow visualization using holographic interferometry

NASA Technical Reports Server (NTRS)

Bryanston-Cross, Peter J.

1987-01-01

An account is made of some of the applications of holographic interferometry to the visualization of transonic flows. In the case of the compressor shock visualization, the method is used regularly and has moved from being a research department invention to a design test tool. With the implementation of automatic processing and simple digitization systems, holographic vibrational analysis has also moved into routine nondestructive testing. The code verification interferograms were instructive, but the main turbomachinery interest is now in 3 dimensional flows. A major data interpretation effort will be required to compute tomographically the 3 dimensional flow around the leading or the trailing edges of a rotating blade row. The bolt on approach shows the potential application to current unsteady flows of interest. In particular that of the rotor passing and vortex interaction effects is experienced by the new generation of unducted fans. The turbocharger tests presents a new area for the application of holography.

The investigation of flow instabilities on a rotating disk with curvature in the radial direction

NASA Technical Reports Server (NTRS)

Intemann, P. A.; Clarkson, M. H.

1982-01-01

The major objective is to explore any visible differences of the flow field with wall curvature of the test body, including possible interaction between Taylor-Gortler instabilities present along concave walls and the inflexional instabilities investigated here. An experimental study was conducted with emphasis placed on making visual observations and recording photographically the flow instabilities present under three different rotating bodies: a flat disk, a concave paraboloid, and a convex paraboloid. The data collected for the three test bodies lead to the conclusion that the wall curvature of the concave and convex paraboloids did not alter the observed flow field significantly from that observed on the flat disk.

Plasticity of the human otolith-ocular reflex

NASA Technical Reports Server (NTRS)

Wall, C. 3rd; Smith, T. R.; Furman, J. M.

1992-01-01

The eye movement response to earth vertical axis rotation in the dark, a semicircular canal stimulus, can be altered by prior exposure to combined visual-vestibular stimuli. Such plasticity of the vestibulo-ocular reflex has not been described for earth horizontal axis rotation, a dynamic otolith stimulus. Twenty normal human subjects underwent one of two types of adaptation paradigms designed either to attenuate or enhance the gain of the semicircular canal-ocular reflex prior to undergoing otolith-ocular reflex testing with horizontal axis rotation. The adaptation paradigm paired a 0.2 Hz sinusoidal rotation about a vertical axis with a 0.2 Hz optokinetic stripe pattern that was deliberately mismatched in peak velocity. Pre- and post-adaptation horizontal axis rotations were at 60 degrees/s in the dark and produced a modulation in the slow component velocity of nystagmus having a frequency of 0.17 Hz due to putative stimulation of the otolith organs. Results showed that the magnitude of this modulation component response was altered in a manner similar to the alteration in semicircular canal-ocular responses. These results suggest that physiologic alteration of the vestibulo-ocular reflex using deliberately mismatched visual and semicircular canal stimuli induces changes in both canal-ocular and otolith-ocular responses. We postulate, therefore, that central nervous system pathways responsible for controlling the gains of canal-ocular and otolith-ocular reflexes are shared.

Volunteer Interacting with a Rotating Chair Demonstration

NASA Technical Reports Server (NTRS)

2002-01-01

Brad McLain for the Space Biology Museum Network spins a volunteer in a rotating chair to illustrate how dependent the human vestibular system is on visual cues. The volunteer's thumbs indicate which way she thinks she is turning. Similar tests are conducted on astronauts to study how they adapt to space and readapt to Earth. The activity was part of the Space Research and You education event held by NASA's Office of Biological and Physical Research on June 25, 2002, in Arlington, VA, to highlight the research that will be conducted on STS-107.

A Rotatable Quality Control Phantom for Evaluating the Performance of Flat Panel Detectors in Imaging Moving Objects.

PubMed

Haga, Yoshihiro; Chida, Koichi; Inaba, Yohei; Kaga, Yuji; Meguro, Taiichiro; Zuguchi, Masayuki

2016-02-01

As the use of diagnostic X-ray equipment with flat panel detectors (FPDs) has increased, so has the importance of proper management of FPD systems. To ensure quality control (QC) of FPD system, an easy method for evaluating FPD imaging performance for both stationary and moving objects is required. Until now, simple rotatable QC phantoms have not been available for the easy evaluation of the performance (spatial resolution and dynamic range) of FPD in imaging moving objects. We developed a QC phantom for this purpose. It consists of three thicknesses of copper and a rotatable test pattern of piano wires of various diameters. Initial tests confirmed its stable performance. Our moving phantom is very useful for QC of FPD images of moving objects because it enables visual evaluation of image performance (spatial resolution and dynamic range) easily.

Influence of eye rotation on peripheral eye length measurement obtained with a partial coherence interferometry instrument.

PubMed

Verkicharla, Pavan K; Suheimat, Marwan; Mallen, Edward A H; Atchison, David A

2014-01-01

The eye rotation approach for measuring peripheral eye length leads to concern about whether the rotation influences results, such as through pressure exerted by eyelids or extra-ocular muscles. This study investigated whether this approach is valid. Peripheral eye lengths were measured with a Lenstar LS 900 biometer for eye rotation and no-eye rotation conditions (head rotation for horizontal meridian and instrument rotation for vertical meridian). Measurements were made for 23 healthy young adults along the horizontal visual field (± 30°) and, for a subset of eight participants along the vertical visual field (± 25°). To investigate the influence of the duration of eye rotation, for six participants measurements were made at 0, 60, 120, 180 and 210 s after eye rotation to ± 30° along horizontal and vertical visual fields. Peripheral eye lengths were not significantly different for the conditions along the vertical meridian (F1,7 = 0.16, p = 0.71). The peripheral eye lengths for the conditions were significantly different along the horizontal meridian (F1,22 = 4.85, p = 0.04), although not at individual positions (p ≥ 0.10) and were not important. There were no apparent differences between the emmetropic and myopic groups. There was no significant change in eye length at any position after maintaining position for 210 s. Eye rotation and no-eye rotation conditions were similar for measuring peripheral eye lengths along horizontal and vertical visual field meridians at ± 30° and ± 25°, respectively. Either condition can be used to estimate retinal shape from peripheral eye lengths. © 2013 The Authors Ophthalmic & Physiological Optics © 2013 The College of Optometrists.

Tiger salamanders' (Ambystoma tigrinum) response learning and usage of visual cues.

PubMed

Kundey, Shannon M A; Millar, Roberto; McPherson, Justin; Gonzalez, Maya; Fitz, Aleyna; Allen, Chadbourne

2016-05-01

We explored tiger salamanders' (Ambystoma tigrinum) learning to execute a response within a maze as proximal visual cue conditions varied. In Experiment 1, salamanders learned to turn consistently in a T-maze for reinforcement before the maze was rotated. All learned the initial task and executed the trained turn during test, suggesting that they learned to demonstrate the reinforced response during training and continued to perform it during test. In a second experiment utilizing a similar procedure, two visual cues were placed consistently at the maze junction. Salamanders were reinforced for turning towards one cue. Cue placement was reversed during test. All learned the initial task, but executed the trained turn rather than turning towards the visual cue during test, evidencing response learning. In Experiment 3, we investigated whether a compound visual cue could control salamanders' behaviour when it was the only cue predictive of reinforcement in a cross-maze by varying start position and cue placement. All learned to turn in the direction indicated by the compound visual cue, indicating that visual cues can come to control their behaviour. Following training, testing revealed that salamanders attended to stimuli foreground over background features. Overall, these results suggest that salamanders learn to execute responses over learning to use visual cues but can use visual cues if required. Our success with this paradigm offers the potential in future studies to explore salamanders' cognition further, as well as to shed light on how features of the tiger salamanders' life history (e.g. hibernation and metamorphosis) impact cognition.

Systematic distortions of perceptual stability investigated using immersive virtual reality

PubMed Central

Tcheang, Lili; Gilson, Stuart J.; Glennerster, Andrew

2010-01-01

Using an immersive virtual reality system, we measured the ability of observers to detect the rotation of an object when its movement was yoked to the observer's own translation. Most subjects had a large bias such that a static object appeared to rotate away from them as they moved. Thresholds for detecting target rotation were similar to those for an equivalent speed discrimination task carried out by static observers, suggesting that visual discrimination is the predominant limiting factor in detecting target rotation. Adding a stable visual reference frame almost eliminated the bias. Varying the viewing distance of the target had little effect, consistent with observers under-estimating distance walked. However, accuracy of walking to a briefly presented visual target was high and not consistent with an under-estimation of distance walked. We discuss implications for theories of a task-independent representation of visual space. PMID:15845248

Optokinetic motion sickness - Attenuation of visually-induced apparent self-rotation by passive head movements

NASA Technical Reports Server (NTRS)

Teixeira, R. A.; Lackner, J. R.

1979-01-01

An experimental study was conducted on seven normal subjects to evaluate the effectiveness of passive head movements in suppressing the optokinetically-induced illusory self-rotation. Visual simulation was provided by a servo-controlled optokinetic drum. Each subject participated in two experimental sessions. In one condition, the subject's head remained stationary while he gazed passively at a moving stripe pattern. In the other, he gazed passively and relaxed his neck muscles while his head was rotated from side to side. It appears that suppression of optokinetically-induced illusory self-rotation with passive head movements results from the operation of a spatial constancy mechanism interrelating visual, vestibular, and kinesthetic information on ongoing body orientation. The results support the view that optokinetic 'motion sickness' is related, at least in part, to an oculomotor disturbance rather than a visually triggered disturbance of specifically vestibular etiology.

The Effect of Mental Rotation on Surgical Pathological Diagnosis.

PubMed

Park, Heejung; Kim, Hyun Soo; Cha, Yoon Jin; Choi, Junjeong; Minn, Yangki; Kim, Kyung Sik; Kim, Se Hoon

2018-05-01

Pathological diagnosis involves very delicate and complex consequent processing that is conducted by a pathologist. The recognition of false patterns might be an important cause of misdiagnosis in the field of surgical pathology. In this study, we evaluated the influence of visual and cognitive bias in surgical pathologic diagnosis, focusing on the influence of "mental rotation." We designed three sets of the same images of uterine cervix biopsied specimens (original, left to right mirror images, and 180-degree rotated images), and recruited 32 pathologists to diagnose the 3 set items individually. First, the items found to be adequate for analysis by classical test theory, Generalizability theory, and item response theory. The results showed statistically no differences in difficulty, discrimination indices, and response duration time between the image sets. Mental rotation did not influence the pathologists' diagnosis in practice. Interestingly, outliers were more frequent in rotated image sets, suggesting that the mental rotation process may influence the pathological diagnoses of a few individual pathologists. © Copyright: Yonsei University College of Medicine 2018.

Error amplification to promote motor learning and motivation in therapy robotics.

PubMed

Shirzad, Navid; Van der Loos, H F Machiel

2012-01-01

To study the effects of different feedback error amplification methods on a subject's upper-limb motor learning and affect during a point-to-point reaching exercise, we developed a real-time controller for a robotic manipulandum. The reaching environment was visually distorted by implementing a thirty degrees rotation between the coordinate systems of the robot's end-effector and the visual display. Feedback error amplification was provided to subjects as they trained to learn reaching within the visually rotated environment. Error amplification was provided either visually or through both haptic and visual means, each method with two different amplification gains. Subjects' performance (i.e., trajectory error) and self-reports to a questionnaire were used to study the speed and amount of adaptation promoted by each error amplification method and subjects' emotional changes. We found that providing haptic and visual feedback promotes faster adaptation to the distortion and increases subjects' satisfaction with the task, leading to a higher level of attentiveness during the exercise. This finding can be used to design a novel exercise regimen, where alternating between error amplification methods is used to both increase a subject's motor learning and maintain a minimum level of motivational engagement in the exercise. In future experiments, we will test whether such exercise methods will lead to a faster learning time and greater motivation to pursue a therapy exercise regimen.

Spatial effects of shifting prisms on properties of posterior parietal cortex neurons

PubMed Central

Karkhanis, Anushree N; Heider, Barbara; Silva, Fabian Muñoz; Siegel, Ralph M

2014-01-01

The posterior parietal cortex contains neurons that respond to visual stimulation and motor behaviour. The objective of the current study was to test short-term adaptation in neurons in macaque area 7a and the dorsal prelunate during visually guided reaching using Fresnel prisms that displaced the visual field. The visual perturbation shifted the eye position and created a mismatch between perceived and actual reach location. Two non-human primates were trained to reach to visual targets before, during and after prism exposure while fixating the reach target in different locations. They were required to reach to the physical location of the reach target and not the perceived, displaced location. While behavioural adaptation to the prisms occurred within a few trials, the majority of neurons responded to the distortion either with substantial changes in spatial eye position tuning or changes in overall firing rate. These changes persisted even after prism removal. The spatial changes were not correlated with the direction of induced prism shift. The transformation of gain fields between conditions was estimated by calculating the translation and rotation in Euler angles. Rotations and translations of the horizontal and vertical spatial components occurred in a systematic manner for the population of neurons suggesting that the posterior parietal cortex retains a constant representation of the visual field remapping between experimental conditions. PMID:24928956

Motor expertise and performance in spatial tasks: A meta-analysis.

PubMed

Voyer, Daniel; Jansen, Petra

2017-08-01

The present study aimed to provide a summary of findings relevant to the influence of motor expertise on performance in spatial tasks and to examine potential moderators of this effect. Studies of relevance were those in which individuals involved in activities presumed to require motor expertise were compared to non-experts in such activities. A final set of 62 effect sizes from 33 samples was included in a multilevel meta-analysis. The results showed an overall advantage in favor of motor experts in spatial tasks (d=0.38). However, the magnitude of that effect was moderated by expert type (athlete, open skills/ball sports, runner/cyclist, gymnast/dancers, musicians), stimulus type (2D, blocks, bodies, others), test category (mental rotation, spatial perception, spatial visualization), specific test (Mental Rotations Test, generic mental rotation, disembedding, rod-and-frame test, other), and publication status. These findings are discussed in the context of embodied cognition and the potential role of activities requiring motor expertise in promoting good spatial performance. Copyright © 2017 Elsevier B.V. All rights reserved.

Role of Self-Generated Odor Cues in Contextual Representation

PubMed Central

Aikath, Devdeep; Weible, Aldis P; Rowland, David C; Kentros, Clifford G

2014-01-01

As first demonstrated in the patient H.M., the hippocampus is critically involved in forming episodic memories, the recall of “what” happened “where” and “when.” In rodents, the clearest functional correlate of hippocampal primary neurons is the place field: a cell fires predominantly when the animal is in a specific part of the environment, typically defined relative to the available visuospatial cues. However, rodents have relatively poor visual acuity. Furthermore, they are highly adept at navigating in total darkness. This raises the question of how other sensory modalities might contribute to a hippocampal representation of an environment. Rodents have a highly developed olfactory system, suggesting that cues such as odor trails may be important. To test this, we familiarized mice to a visually cued environment over a number of days while maintaining odor cues. During familiarization, self-generated odor cues unique to each animal were collected by re-using absorbent paperboard flooring from one session to the next. Visual and odor cues were then put in conflict by counter-rotating the recording arena and the flooring. Perhaps surprisingly, place fields seemed to follow the visual cue rotation exclusively, raising the question of whether olfactory cues have any influence at all on a hippocampal spatial representation. However, subsequent removal of the familiar, self-generated odor cues severely disrupted both long-term stability and rotation to visual cues in a novel environment. Our data suggest that odor cues, in the absence of additional rule learning, do not provide a discriminative spatial signal that anchors place fields. Such cues do, however, become integral to the context over time and exert a powerful influence on the stability of its hippocampal representation. © 2014 The Authors. Hippocampus Published by Wiley Periodicals, Inc. PMID:24753119

Visuomotor Transformation in the Fly Gaze Stabilization System

PubMed Central

Huston, Stephen J; Krapp, Holger G

2008-01-01

For sensory signals to control an animal's behavior, they must first be transformed into a format appropriate for use by its motor systems. This fundamental problem is faced by all animals, including humans. Beyond simple reflexes, little is known about how such sensorimotor transformations take place. Here we describe how the outputs of a well-characterized population of fly visual interneurons, lobula plate tangential cells (LPTCs), are used by the animal's gaze-stabilizing neck motor system. The LPTCs respond to visual input arising from both self-rotations and translations of the fly. The neck motor system however is involved in gaze stabilization and thus mainly controls compensatory head rotations. We investigated how the neck motor system is able to selectively extract rotation information from the mixed responses of the LPTCs. We recorded extracellularly from fly neck motor neurons (NMNs) and mapped the directional preferences across their extended visual receptive fields. Our results suggest that—like the tangential cells—NMNs are tuned to panoramic retinal image shifts, or optic flow fields, which occur when the fly rotates about particular body axes. In many cases, tangential cells and motor neurons appear to be tuned to similar axes of rotation, resulting in a correlation between the coordinate systems the two neural populations employ. However, in contrast to the primarily monocular receptive fields of the tangential cells, most NMNs are sensitive to visual motion presented to either eye. This results in the NMNs being more selective for rotation than the LPTCs. Thus, the neck motor system increases its rotation selectivity by a comparatively simple mechanism: the integration of binocular visual motion information. PMID:18651791

Visual dysfunction in Parkinson’s disease

PubMed Central

Weil, Rimona S.; Schrag, Anette E.; Warren, Jason D.; Crutch, Sebastian J.; Lees, Andrew J.; Morris, Huw R.

2016-01-01

Patients with Parkinson’s disease have a number of specific visual disturbances. These include changes in colour vision and contrast sensitivity and difficulties with complex visual tasks such as mental rotation and emotion recognition. We review changes in visual function at each stage of visual processing from retinal deficits, including contrast sensitivity and colour vision deficits to higher cortical processing impairments such as object and motion processing and neglect. We consider changes in visual function in patients with common Parkinson’s disease-associated genetic mutations including GBA and LRRK2. We discuss the association between visual deficits and clinical features of Parkinson’s disease such as rapid eye movement sleep behavioural disorder and the postural instability and gait disorder phenotype. We review the link between abnormal visual function and visual hallucinations, considering current models for mechanisms of visual hallucinations. Finally, we discuss the role of visuo-perceptual testing as a biomarker of disease and predictor of dementia in Parkinson’s disease. PMID:27412389

Mental rotation impairs attention shifting and short-term memory encoding: neurophysiological evidence against the response-selection bottleneck model of dual-task performance.

PubMed

Pannebakker, Merel M; Jolicœur, Pierre; van Dam, Wessel O; Band, Guido P H; Ridderinkhof, K Richard; Hommel, Bernhard

2011-09-01

Dual tasks and their associated delays have often been used to examine the boundaries of processing in the brain. We used the dual-task procedure and recorded event-related potentials (ERPs) to investigate how mental rotation of a first stimulus (S1) influences the shifting of visual-spatial attention to a second stimulus (S2). Visual-spatial attention was monitored by using the N2pc component of the ERP. In addition, we examined the sustained posterior contralateral negativity (SPCN) believed to index the retention of information in visual short-term memory. We found modulations of both the N2pc and the SPCN, suggesting that engaging mechanisms of mental rotation impairs the deployment of visual-spatial attention and delays the passage of a representation of S2 into visual short-term memory. Both results suggest interactions between mental rotation and visual-spatial attention in capacity-limited processing mechanisms indicating that response selection is not pivotal in dual-task delays and all three processes are likely to share a common resource like executive control. Copyright © 2011 Elsevier Ltd. All rights reserved.

Effects of auditory information on self-motion perception during simultaneous presentation of visual shearing motion

PubMed Central

Tanahashi, Shigehito; Ashihara, Kaoru; Ujike, Hiroyasu

2015-01-01

Recent studies have found that self-motion perception induced by simultaneous presentation of visual and auditory motion is facilitated when the directions of visual and auditory motion stimuli are identical. They did not, however, examine possible contributions of auditory motion information for determining direction of self-motion perception. To examine this, a visual stimulus projected on a hemisphere screen and an auditory stimulus presented through headphones were presented separately or simultaneously, depending on experimental conditions. The participant continuously indicated the direction and strength of self-motion during the 130-s experimental trial. When the visual stimulus with a horizontal shearing rotation and the auditory stimulus with a horizontal one-directional rotation were presented simultaneously, the duration and strength of self-motion perceived in the opposite direction of the auditory rotation stimulus were significantly longer and stronger than those perceived in the same direction of the auditory rotation stimulus. However, the auditory stimulus alone could not sufficiently induce self-motion perception, and if it did, its direction was not consistent within each experimental trial. We concluded that auditory motion information can determine perceived direction of self-motion during simultaneous presentation of visual and auditory motion information, at least when visual stimuli moved in opposing directions (around the yaw-axis). We speculate that the contribution of auditory information depends on the plausibility and information balance of visual and auditory information. PMID:26113828

Comparison of 2 oral ultrasonography contrast agents: simethicone-coated cellulose and simethicone-water rotation in improving pancreatic visualization.

PubMed

Ishigami, Kousei; Abu-Yousef, Dina M; Kao, Simon C S; Abu-Yousef, Monzer M

2014-06-01

The purpose of this study was to prospectively compare the efficacy of 2 oral ultrasonography (US) contrast agents (simethicone-water rotation [SWR] and simethicone-coated cellulose [SCC]) in improving visualization of the pancreas. Two sessions (SWR and SCC) of transabdominal US studies were performed on 38 healthy volunteers. In each session, US images were obtained in precontrast supine and upright positions and postcontrast supine and upright positions. The visualization of the pancreas was graded on a scale of 1 to 5 (1 = nonvisualization, 5 = excellent visualization), grading the head, body, and tail separately. In the supine position, SWR significantly improved the visualization of the pancreatic head, body, and tail, whereas there were no significant differences between SCC and precontrast images. Simethicone-water rotation showed significantly better visualization than SCC. The average scores of the head, body, and tail of the pancreas that graded 4 or more were 15.8% of precontrast, 21.1% of SCC, and 50% of SWR. In the upright position, both SWR and SCC significantly improved the visualization of the pancreas, except for the pancreatic body on SCC. There were no significant differences between SWR and SCC. The average scores that graded 4 or more were 26.3% of precontrast, 57.9% of SCC, and 65.8% of SWR. Simethicone-water rotation was more effective than SCC in improving the visualization of the pancreas.

Spatial Abilities during the Circalunar Cycle in Both Sexes

ERIC Educational Resources Information Center

Ostatnikova, Daniela; Hodosy, Julius; Skoknova, Martina; Putz, Zdenek; Kudela, Matus; Celec, Peter

2010-01-01

Spatial abilities vary during the menstrual cycle. The effects of a similar rhythm in men are unknown. Mental rotation and spatial visualization of young healthy volunteers (29 females and 31 males) were tested during the menstrual and periovulatory phase of the menstrual cycle in women, and during the low-testosterone and high-testosterone phases…

Sex-sensitive cognitive performance in untreated patients with early onset gender identity disorder.

PubMed

Haraldsen, I R; Opjordsmoen, S; Egeland, T; Finset, A

2003-10-01

We explored whether the cognitive performance of gender identity disorder patients (GID) was comparable to that of their biological sex or skewed towards that of their gender identity. We tested four potentially sex-sensitive cognitive factors (rotation, visualization, perception, and verbalization) as well as two neutral factors (logic and arithmetic) in GID patients from Norway (GID-N, n = 33) or the USA (GID-US, n = 19) and in a control group (C, n = 29). The testing was undertaken prior to cross sex hormone treatment. Four-way ANOVA was applied in the final analysis of the cognitive performance and its dependency on different predictors (age, biological sex, education, group). In both GID groups as well as in the control group (C) males excelled in visualization and rotation, also when controlling for potential confounders (biological sex, group, age and education). No female advantage was detected. Furthermore, no interaction between biological sex and group assignment was revealed in the samples. In this study the cognitive pattern of GID patients is consistent with that of their biological sex and not that of their gender identity.

Optical high-resolution analysis of rotational movement: testing circular spatial filter velocimetry (CSFV) with rotating biological cells

NASA Astrophysics Data System (ADS)

Schaeper, M.; Schmidt, R.; Kostbade, R.; Damaschke, N.; Gimsa, J.

2016-07-01

Circular spatial filtering velocimetry (CSFV) was tested during the microscopic registration of the individual rotations of baker’s yeast cells. Their frequency-dependent rotation (electrorotation; ER) was induced in rotating electric fields, which were generated in a glass chip chamber with four electrodes (600 μm tip-to-tip distance). The electrodes were driven with sinusoidal quadrature signals of 5 or 8 V PP with frequencies up to 3 MHz. The observed cell rotation was of the order of 1-100 s per revolution. At each measuring frequency, the independent rotations of up to 20 cells were simultaneously recorded with a high-speed camera. CSFV was software-implemented using circular spatial filters with harmonic gratings. ER was proportional to the phase shift between the values of the spatial filtering signal of consecutive frames. ER spectra obtained by CSFV from the rotation velocities at different ER-field frequencies agreed well with manual measurements and theoretical spectra. Oscillations in the rotation velocity of a single cell in the elliptically polarized field near an electrode, which were resolved by CSFV, could not be visually discerned. ER step responses after field-on were recorded at 2500 frames per second. Analysis proved the high temporal resolution of CSFV and revealed a largely linear torque-friction relation during the acceleration phase of ER. Future applications of CSFV will allow for the simple and cheap automated high-resolution analysis of rotational movements where mechanical detection has too low a resolution or is not possible, e.g. in polluted environments or for gas and fluid vortices, microscopic objects, etc.

A foundation for savantism? Visuo-spatial synaesthetes present with cognitive benefits.

PubMed

Simner, Julia; Mayo, Neil; Spiller, Mary-Jane

2009-01-01

Individuals with 'time-space' synaesthesia have conscious awareness of mappings between time and space (e.g., they may see months arranged in an ellipse, or years as columns or spirals). These mappings exist in the 3D space around the body or in a virtual space within the mind's eye. Our study shows that these extra-ordinary mappings derive from, or give rise to, superior abilities in the two domains linked by this cross-modal phenomenon (i.e., abilities relating to time, and visualised space). We tested ten time-space synaesthetes with a battery of temporal and visual/spatial tests. Our temporal battery (the Edinburgh [Public and Autobiographical] Events Battery - EEB) assessed both autobiographical and non-autobiographical memory for events. Our visual/spatial tests assessed the ability to manipulate real or imagined objects in 3D space (the Three Dimensional Constructional Praxis test; Visual Object and Space Perception Battery, University of Southern California Mental Rotation Test) as well as assessing visual memory recall (Visual Patterns Test - VPT). Synaesthetes' performance was superior to the control population in every assessment, but was not superior in tasks that do not draw upon abilities related to their mental calendars. Our paper discusses the implications of this temporal-spatial advantage as it relates to normal processing, synaesthetic processing, and to the savant-like condition of hyperthymestic syndrome (Parker et al., 2006).

A Rotational Motion Perception Neural Network Based on Asymmetric Spatiotemporal Visual Information Processing.

PubMed

Hu, Bin; Yue, Shigang; Zhang, Zhuhong

All complex motion patterns can be decomposed into several elements, including translation, expansion/contraction, and rotational motion. In biological vision systems, scientists have found that specific types of visual neurons have specific preferences to each of the three motion elements. There are computational models on translation and expansion/contraction perceptions; however, little has been done in the past to create computational models for rotational motion perception. To fill this gap, we proposed a neural network that utilizes a specific spatiotemporal arrangement of asymmetric lateral inhibited direction selective neural networks (DSNNs) for rotational motion perception. The proposed neural network consists of two parts-presynaptic and postsynaptic parts. In the presynaptic part, there are a number of lateral inhibited DSNNs to extract directional visual cues. In the postsynaptic part, similar to the arrangement of the directional columns in the cerebral cortex, these direction selective neurons are arranged in a cyclic order to perceive rotational motion cues. In the postsynaptic network, the delayed excitation from each direction selective neuron is multiplied by the gathered excitation from this neuron and its unilateral counterparts depending on which rotation, clockwise (cw) or counter-cw (ccw), to perceive. Systematic experiments under various conditions and settings have been carried out and validated the robustness and reliability of the proposed neural network in detecting cw or ccw rotational motion. This research is a critical step further toward dynamic visual information processing.All complex motion patterns can be decomposed into several elements, including translation, expansion/contraction, and rotational motion. In biological vision systems, scientists have found that specific types of visual neurons have specific preferences to each of the three motion elements. There are computational models on translation and expansion/contraction perceptions; however, little has been done in the past to create computational models for rotational motion perception. To fill this gap, we proposed a neural network that utilizes a specific spatiotemporal arrangement of asymmetric lateral inhibited direction selective neural networks (DSNNs) for rotational motion perception. The proposed neural network consists of two parts-presynaptic and postsynaptic parts. In the presynaptic part, there are a number of lateral inhibited DSNNs to extract directional visual cues. In the postsynaptic part, similar to the arrangement of the directional columns in the cerebral cortex, these direction selective neurons are arranged in a cyclic order to perceive rotational motion cues. In the postsynaptic network, the delayed excitation from each direction selective neuron is multiplied by the gathered excitation from this neuron and its unilateral counterparts depending on which rotation, clockwise (cw) or counter-cw (ccw), to perceive. Systematic experiments under various conditions and settings have been carried out and validated the robustness and reliability of the proposed neural network in detecting cw or ccw rotational motion. This research is a critical step further toward dynamic visual information processing.

Prediction of the body rotation-induced torques on the arm during reaching movements: evidence from a proprioceptively deafferented subject.

PubMed

Guillaud, Etienne; Simoneau, Martin; Blouin, Jean

2011-06-01

Reaching for a target while rotating the trunk generates substantial Coriolis and centrifugal torques that push the arm in the opposite direction of the rotations. These torques rarely perturb movement accuracy, suggesting that they are compensated for during the movement. Here we tested whether signals generated during body motion (e.g., vestibular) can be used to predict the torques induced by the body rotation and to modify the motor commands accordingly. We asked a deafferented subject to reach for a memorized visual target in darkness. At the onset of the reaching, the patient was rotated 25° or 40° in the clockwise or the counterclockwise directions. During the rotation, the patient's head remained either fixed in space (Head-Fixed condition) or fixed on the trunk (Head Rotation condition). At the rotation onset, the deafferented patient's hand largely deviated from the mid-sagittal plane in both conditions. The hand deviations were compensated for in the Head Rotation condition only. These results highlight the computational faculty of the brain and show that body rotation-related information can be processed for predicting the consequence of the rotation dynamics on the reaching arm movements. Copyright © 2011 Elsevier Ltd. All rights reserved.

Interaction of vestibular, echolocation, and visual modalities guiding flight by the big brown bat, Eptesicus fuscus.

PubMed

Horowitz, Seth S; Cheney, Cheryl A; Simmons, James A

2004-01-01

The big brown bat (Eptesicus fuscus) is an aerial-feeding insectivorous species that relies on echolocation to avoid obstacles and to detect flying insects. Spatial perception in the dark using echolocation challenges the vestibular system to function without substantial visual input for orientation. IR thermal video recordings show the complexity of bat flights in the field and suggest a highly dynamic role for the vestibular system in orientation and flight control. To examine this role, we carried out laboratory studies of flight behavior under illuminated and dark conditions in both static and rotating obstacle tests while administering heavy water (D2O) to impair vestibular inputs. Eptesicus carried out complex maneuvers through both fixed arrays of wires and a rotating obstacle array using both vision and echolocation, or when guided by echolocation alone. When treated with D2O in combination with lack of visual cues, bats showed considerable decrements in performance. These data indicate that big brown bats use both vision and echolocation to provide spatial registration for head position information generated by the vestibular system.

Mental Rotation of Tactical Instruction Displays Affects Information Processing Demand and Execution Accuracy in Basketball.

PubMed

Koopmann, Till; Steggemann-Weinrich, Yvonne; Baumeister, Jochen; Krause, Daniel

2017-09-01

In sports games, coaches often use tactic boards to present tactical instructions during time-outs (e.g., 20 s to 60 s in basketball). Instructions should be presented in a way that enables fast and errorless information processing for the players. The aim of this study was to test the effect of different orientations of visual tactical displays on observation time and execution performance. High affordances in visual-spatial transformation (e.g., mental rotation processes) might impede information processing and might decrease execution performance with regard to the instructed playing patterns. In a within-subjects design with 1 factor, 10 novice students were instructed with visual tactical instructions of basketball playing patterns with different orientations either showing the playing pattern with low spatial disparity to the players' on-court perspective (basket on top) or upside down (basket on bottom). The self-chosen time for watching the pattern before execution was significantly shorter and spatial accuracy in pattern execution was significantly higher when the instructional perspective and the real perspective on the basketball court had a congruent orientation. The effects might be explained by interfering mental rotation processes that are necessary to transform the instructional perspective into the players' actual perspective while standing on the court or imagining themselves standing on the court. According to these results, coaches should align their tactic boards to their players' on-court viewing perspective.

Fast instantaneous center of rotation estimation algorithm for a skied-steered robot

NASA Astrophysics Data System (ADS)

Kniaz, V. V.

2015-05-01

Skid-steered robots are widely used as mobile platforms for machine vision systems. However it is hard to achieve a stable motion of such robots along desired trajectory due to an unpredictable wheel slip. It is possible to compensate the unpredictable wheel slip and stabilize the motion of the robot using visual odometry. This paper presents a fast optical flow based algorithm for estimation of instantaneous center of rotation, angular and longitudinal speed of the robot. The proposed algorithm is based on Horn-Schunck variational optical flow estimation method. The instantaneous center of rotation and motion of the robot is estimated by back projection of optical flow field to the ground surface. The developed algorithm was tested using skid-steered mobile robot. The robot is based on a mobile platform that includes two pairs of differential driven motors and a motor controller. Monocular visual odometry system consisting of a singleboard computer and a low cost webcam is mounted on the mobile platform. A state-space model of the robot was derived using standard black-box system identification. The input (commands) and the output (motion) were recorded using a dedicated external motion capture system. The obtained model was used to control the robot without visual odometry data. The paper is concluded with the algorithm quality estimation by comparison of the trajectories estimated by the algorithm with the data from motion capture system.

[Activities of Psychology Dept., California Univ.

NASA Technical Reports Server (NTRS)

Bridgeman, Bruce

1998-01-01

We have completed two studies during the grant period, with manuscripts published or ready for submission for publication: (1) Dual adaptation and adaptive generalization in the human vestibuloocular reflex and (2) Frequency vs. acceleration specificity in human VOR adaptation. In the 1st study two studies examined the possibility that rotational VOR plasticity is subject to dual adaptation and adaptive generalization. Subjects in the experimental condition were exposed to an altered visual-vestibular environment for about four minutes every day for five consecutive days. The working hours between these testing sessions constituted re-exposure to the normal visual environment. Thus, subjects were repeatedly adapting and re-adapting to both environments which is a condition designed to produce dual adaptation. In each training session a measure of baseline VOR gain was obtained (in the dark). A small laser spot (the only visual stimulus) was systematically moved in the same direction as the subject's head, but by half the angle of rotation (target/head gain = 0.5). This resulted in adaptation values relativized to the non-adapted gain of each subject. These values were then analyzed using an analysis of variance with day and session (within a day) as factors. In the 2nd study human VOR adaption has been assumed to be frequency specific, despite the fact that the semicircular canals are simulated by rotational acceleration and not frequency per se.

Spatial abilities across the adult life span.

PubMed

Borella, Erika; Meneghetti, Chiara; Ronconi, Lucia; De Beni, Rossana

2014-02-01

The study investigates age-related effects across the adult life span on spatial abilities (testing subabilities based on a distinction between spatial visualization, mental rotation, and perspective taking) and spatial self-assessments. The sample consisted of 454 participants (223 women and 231 men) from 20 to 91 years of age. Results showed nonlinear age-related effects for spatial visualization and perspective taking but linear effects for mental rotation; few or no age-related effects were found for spatial self-assessments. Working memory accounted for only a small proportion of the variance in all spatial tasks and had no effect on spatial self-assessments. Overall, our findings suggest that the influence of age on spatial skills across the adult life span is considerable, but the effects of age change as a function of the spatial task considered, and the effect on spatial self-assessment is more marginal.

Mental Health Has a Stronger Association with Patient-Reported Shoulder Pain and Function Than Tear Size in Patients with Full-Thickness Rotator Cuff Tears.

PubMed

Wylie, James D; Suter, Thomas; Potter, Michael Q; Granger, Erin K; Tashjian, Robert Z

2016-02-17

Patient-reported outcome measures have increasingly accompanied objective examination findings in the evaluation of orthopaedic interventions. Our objective was to determine whether a validated measure of mental health (Short Form-36 Mental Component Summary [SF-36 MCS]) or measures of tear severity on magnetic resonance imaging were more strongly associated with self-assessed shoulder pain and function in patients with symptomatic full-thickness rotator cuff tears. One hundred and sixty-nine patients with full-thickness rotator cuff tears were prospectively enrolled. Patients completed the Short Form-36, visual analog scales for shoulder pain and function, the Simple Shoulder Test (SST), and the American Shoulder and Elbow Surgeons (ASES) instrument at the time of diagnosis. Shoulder magnetic resonance imaging examinations were reviewed to document the number of tendons involved, tear size, tendon retraction, and tear surface area. Age, sex, body mass index, number of medical comorbidities, smoking status, and Workers' Compensation status were recorded. Bivariate correlations and multivariate regression models were calculated to identify associations with baseline shoulder scores. The SF-36 MCS had the strongest correlation with the visual analog scale for shoulder pain (Pearson correlation coefficient, -0.48; p < 0.001), the visual analog scale for shoulder function (Pearson correlation coefficient, -0.33; p < 0.001), the SST (Pearson correlation coefficient, 0.37; p < 0.001), and the ASES score (Pearson correlation coefficient, 0.51; p < 0.001). Tear severity only correlated with the visual analog scale for shoulder function; the Pearson correlation coefficient was 0.19 for tear size (p = 0.018), 0.18 for tendon retraction (p = 0.025), 0.18 for tear area (p = 0.022), and 0.20 for the number of tendons involved (p = 0.011). Tear severity did not correlate with other scores in bivariate correlations (all p > 0.05). In all multivariate models, the SF-36 MCS had the strongest association with the visual analog scale for shoulder pain, the visual analog scale for shoulder function, the SST, and the ASES score (all p < 0.001). Patient mental health may play an influential role in patient-reported pain and function in patients with full-thickness rotator cuff tears. Further studies are needed to determine its effect on the outcome of the treatment of rotator cuff disease. Copyright © 2016 by The Journal of Bone and Joint Surgery, Incorporated.

Applications of mental rotation figures of the Shepard and Metzler type and description of a mental rotation stimulus library.

PubMed

Peters, Michael; Battista, Christian

2008-04-01

The 3D cube figures used by Shepard and Metzler [Shepard, R. N., & Metzler, J. (1971). Mental rotation of three-dimensional objects. Science, 171, 701-703] have been applied in a broad range of studies on mental rotation. This note provides a brief background on these figures, their general use in cognitive psychology and their role in studying spatial behavior. In particular, it is pointed out that large sex differences with the 3D mental rotation figures tend to be observed only in particular tasks, such as the Vandenberg and Kuse test [Vandenberg, S. G., & Kuse, A. R. (1978). Mental rotations, a group test of three-dimensional spatial visualization. Perceptual and Motor Skills, 47, 599-604] that involve multiple figures within a single problem. In contrast, pairwise presentation of the same 3D figures yields either small or no significant sex differences. In the context of the very broad range of ongoing research done with 3D figures, and the desirability of uniformity in the stimulus material used, we introduce a library of 16 cube mental rotation figures, each presented in orientations ranging from 0 to 360 degr in 5 degr steps, and with its mirror image, for a total of 2336 figures. This library, freely available to researchers, will help in the creation of mental rotation tasks both for presentation on the computer screen and for pencil and paper applications.

Spacelab

NASA Image and Video Library

1992-01-01

Astronaut Ulf Merbold on the stationary seat of the mini-sled, stares into an umbrella-shaped rotating dome with colored dots. Astronaut Merbold, assisted by astronaut David Hilmer, are conducting the Visual Simulator Experiment, a space physiology experiment. The Visual Stimulator Experiment measures the relative importance of visual and vestibular information in determining body orientation. When a person looks at a rotating visual field, a false sensation of self-rotation, called circularvection, results. In weightlessness, circularvection should increase immediately and may continue to increase as the nervous system comes to rely more on visual than vestibular cues. As Astronaut Merbold stares into the rotating dome with a pattern of colored dots and its interior, he turns a knob to indicate his perception of body rotation. The strength of circularvection is calculated by comparing signals from the dome and the knob. The greater the false sense of circularvection, the more the subject is relying on visual information instead of otolith information. The IML-1 mission was the first in a series of Shuttle flights dedicated to fundamental materials and life sciences research with the international partners. The participating space agencies included: NASA, the 14-nation European Space Agency (ESA), the Canadian Space Agency (CSA), the French National Center of Space Studies (CNES), the German Space Agency and the German Aerospace Research Establishment (DAR/DLR), and the National Space Development Agency of Japan (NASDA). Managed by the Marshall Space Flight Center, IML-1 was launched on January 22, 1992 aboard the Space Shuttle Orbiter Discovery (STS-42 mission).

Visual Form Perception Can Be a Cognitive Correlate of Lower Level Math Categories for Teenagers.

PubMed

Cui, Jiaxin; Zhang, Yiyun; Cheng, Dazhi; Li, Dawei; Zhou, Xinlin

2017-01-01

Numerous studies have assessed the cognitive correlates of performance in mathematics, but little research has been conducted to systematically examine the relations between visual perception as the starting point of visuospatial processing and typical mathematical performance. In the current study, we recruited 223 seventh graders to perform a visual form perception task (figure matching), numerosity comparison, digit comparison, exact computation, approximate computation, and curriculum-based mathematical achievement tests. Results showed that, after controlling for gender, age, and five general cognitive processes (choice reaction time, visual tracing, mental rotation, spatial working memory, and non-verbal matrices reasoning), visual form perception had unique contributions to numerosity comparison, digit comparison, and exact computation, but had no significant relation with approximate computation or curriculum-based mathematical achievement. These results suggest that visual form perception is an important independent cognitive correlate of lower level math categories, including the approximate number system, digit comparison, and exact computation.

Ontogenetic improvement of visual function in the medaka Oryzias latipes based on an optomotor testing system for larval and adult fish

USGS Publications Warehouse

Carvalho, Paulo S. M.; Noltie, Douglas B.; Tillitt, D.E.

2002-01-01

We developed a system for evaluation of visual function in larval and adult fish. Both optomotor (swimming) and optokinetic (eye movement) responses were monitored and recorded using a system of rotating stripes. The system allowed manipulation of factors such as width of the stripes used, rotation speed of the striped drum, and light illuminance levels within both the scotopic and photopic ranges. Precise control of these factors allowed quantitative measurements of visual acuity and motion detection. Using this apparatus, we tested the hypothesis that significant posthatch ontogenetic improvements in visual function occur in the medaka Oryzias latipes, and also that this species shows significant in ovo neuronal development. Significant improvements in the acuity angle alpha (ability to discriminate detail) were observed from approximately 5 degrees at hatch to 1 degree in the oldest adult stages. In addition, we measured a significant improvement in flicker fusion thresholds (motion detection skills) between larval and adult life stages within both the scotopic and photopic ranges of light illuminance. Ranges of flicker fusion thresholds (X±SD) at log I=1.96 (photopic) varied from 37.2±1.6 cycles/s in young adults to 18.6±1.6 cycles/s in young larvae 10 days posthatch. At log I=−2.54 (scotopic), flicker fusion thresholds varied from 5.8±0.7 cycles/s in young adults to 1.7±0.4 cycles/s in young larvae 10 days posthatch. Light sensitivity increased approximately 2.9 log units from early hatched larval stages to adults. The demonstrated ontogenetic improvements in visual function probably enable the fish to explore new resources, thereby enlarging their fundamental niche.

Improved US visualization of the pancreatic tail with simethicone, water, and patient rotation.

PubMed

Abu-Yousef, M M; El-Zein, Y

2000-12-01

To evaluate the effect of degassed water, simethicone, and patient rotation on ultrasonographic (US) visualization of the pancreatic tail. Seventy patients in whom visualization of the pancreatic tail was poor at US were reevaluated in the upright position after ingesting 2 cups (500 mL) of water with 80 mg of simethicone followed by rotating three times on the examination table. In a few patients, the right posterior oblique position was used. Pancreatic tail visualization and disbursement of gastric gas were evaluated. Seventy patients who received 500 mL of distilled water only served as control subjects. Pancreatic tail visualization in patients versus control subjects was complete in 55 (79%) versus five (7%) of 70 patients and control subjects, partial in 10 (14%) versus 38 (54%), and not improved in five (7%) versus 27 (39%). The effect on diminishing gastric air was closely correlated with the degree of improved visualization in most patients. All patients tolerated the procedure well, with no side effects. The technique added a mean of 8 versus 5 minutes to the examination in patients versus control subjects. The full acoustic window effect of the simethicone-water mixture lasted approximately 10 minutes. The simethicone-water-rotation technique is simple, safe, inexpensive, and effective for improving pancreatic tail visualization in ambulatory patients and is superior to the use of water alone.

Spherical Coordinate Systems for Streamlining Suited Mobility Analysis

NASA Technical Reports Server (NTRS)

Benson, Elizabeth; Cowley, Matthew; Harvill, Lauren; Rajulu. Sudhakar

2015-01-01

Introduction: When describing human motion, biomechanists generally report joint angles in terms of Euler angle rotation sequences. However, there are known limitations in using this method to describe complex motions such as the shoulder joint during a baseball pitch. Euler angle notation uses a series of three rotations about an axis where each rotation is dependent upon the preceding rotation. As such, the Euler angles need to be regarded as a set to get accurate angle information. Unfortunately, it is often difficult to visualize and understand these complex motion representations. It has been shown that using a spherical coordinate system allows Anthropometry and Biomechanics Facility (ABF) personnel to increase their ability to transmit important human mobility data to engineers, in a format that is readily understandable and directly translatable to their design efforts. Objectives: The goal of this project was to use innovative analysis and visualization techniques to aid in the examination and comprehension of complex motions. Methods: This project consisted of a series of small sub-projects, meant to validate and verify a new method before it was implemented in the ABF's data analysis practices. A mechanical test rig was built and tracked in 3D using an optical motion capture system. Its position and orientation were reported in both Euler and spherical reference systems. In the second phase of the project, the ABF estimated the error inherent in a spherical coordinate system, and evaluated how this error would vary within the reference frame. This stage also involved expanding a kinematic model of the shoulder to include the rest of the joints of the body. The third stage of the project involved creating visualization methods to assist in interpreting motion in a spherical frame. These visualization methods will be incorporated in a tool to evaluate a database of suited mobility data, which is currently in development. Results: Initial results demonstrated that a spherical coordinate system is helpful in describing and visualizing the motion of a space suit. The system is particularly useful in describing the motion of the shoulder, where multiple degrees of freedom can lead to very complex motion paths.

Illusory motion reversal is caused by rivalry, not by perceptual snapshots of the visual field.

PubMed

Kline, Keith; Holcombe, Alex O; Eagleman, David M

2004-10-01

In stroboscopic conditions--such as motion pictures--rotating objects may appear to rotate in the reverse direction due to under-sampling (aliasing). A seemingly similar phenomenon occurs in constant sunlight, which has been taken as evidence that the visual system processes discrete "snapshots" of the outside world. But if snapshots are indeed taken of the visual field, then when a rotating drum appears to transiently reverse direction, its mirror image should always appeared to reverse direction simultaneously. Contrary to this hypothesis, we found that when observers watched a rotating drum and its mirror image, almost all illusory motion reversals occurred for only one image at a time. This result indicates that the motion reversal illusion cannot be explained by snapshots of the visual field. The same result is found when the two images are presented within one visual hemifield, further ruling out the possibility that discrete sampling of the visual field occurs separately in each hemisphere. The frequency distribution of illusory reversal durations approximates a gamma distribution, suggesting perceptual rivalry as a better explanation for illusory motion reversal. After adaptation of motion detectors coding for the correct direction, the activity of motion-sensitive neurons coding for motion in the reverse direction may intermittently become dominant and drive the perception of motion.

Measuring the interrelations among multiple paradigms of visual attention: an individual differences approach.

PubMed

Huang, Liqiang; Mo, Lei; Li, Ying

2012-04-01

A large part of the empirical research in the field of visual attention has focused on various concrete paradigms. However, as yet, there has been no clear demonstration of whether or not these paradigms are indeed measuring the same underlying construct. We collected a very large data set (nearly 1.3 million trials) to address this question. We tested 257 participants on nine paradigms: conjunction search, configuration search, counting, tracking, feature access, spatial pattern, response selection, visual short-term memory, and change blindness. A fairly general attention factor was identified. Some of the participants were also tested on eight other paradigms. This general attention factor was found to be correlated with intelligence, visual marking, task switching, mental rotation, and Stroop task. On the other hand, a few paradigms that are very important in the attention literature (attentional capture, consonance-driven orienting, and inhibition of return) were found to be dissociated from this general attention factor.

Body Context and Posture Affect Mental Imagery of Hands

PubMed Central

Ionta, Silvio; Perruchoud, David; Draganski, Bogdan; Blanke, Olaf

2012-01-01

Different visual stimuli have been shown to recruit different mental imagery strategies. However the role of specific visual stimuli properties related to body context and posture in mental imagery is still under debate. Aiming to dissociate the behavioural correlates of mental processing of visual stimuli characterized by different body context, in the present study we investigated whether the mental rotation of stimuli showing either hands as attached to a body (hands-on-body) or not (hands-only), would be based on different mechanisms. We further examined the effects of postural changes on the mental rotation of both stimuli. Thirty healthy volunteers verbally judged the laterality of rotated hands-only and hands-on-body stimuli presented from the dorsum- or the palm-view, while positioning their hands on their knees (front postural condition) or behind their back (back postural condition). Mental rotation of hands-only, but not of hands-on-body, was modulated by the stimulus view and orientation. Additionally, only the hands-only stimuli were mentally rotated at different speeds according to the postural conditions. This indicates that different stimulus-related mechanisms are recruited in mental rotation by changing the bodily context in which a particular body part is presented. The present data suggest that, with respect to hands-only, mental rotation of hands-on-body is less dependent on biomechanical constraints and proprioceptive input. We interpret our results as evidence for preferential processing of visual- rather than kinesthetic-based mechanisms during mental transformation of hands-on-body and hands-only, respectively. PMID:22479618

Mirror reversal and visual rotation are learned and consolidated via separate mechanisms: recalibrating or learning de novo?

PubMed

Telgen, Sebastian; Parvin, Darius; Diedrichsen, Jörn

2014-10-08

Motor learning tasks are often classified into adaptation tasks, which involve the recalibration of an existing control policy (the mapping that determines both feedforward and feedback commands), and skill-learning tasks, requiring the acquisition of new control policies. We show here that this distinction also applies to two different visuomotor transformations during reaching in humans: Mirror-reversal (left-right reversal over a mid-sagittal axis) of visual feedback versus rotation of visual feedback around the movement origin. During mirror-reversal learning, correct movement initiation (feedforward commands) and online corrections (feedback responses) were only generated at longer latencies. The earliest responses were directed into a nonmirrored direction, even after two training sessions. In contrast, for visual rotation learning, no dependency of directional error on reaction time emerged, and fast feedback responses to visual displacements of the cursor were immediately adapted. These results suggest that the motor system acquires a new control policy for mirror reversal, which initially requires extra processing time, while it recalibrates an existing control policy for visual rotations, exploiting established fast computational processes. Importantly, memory for visual rotation decayed between sessions, whereas memory for mirror reversals showed offline gains, leading to better performance at the beginning of the second session than in the end of the first. With shifts in time-accuracy tradeoff and offline gains, mirror-reversal learning shares common features with other skill-learning tasks. We suggest that different neuronal mechanisms underlie the recalibration of an existing versus acquisition of a new control policy and that offline gains between sessions are a characteristic of latter. Copyright © 2014 the authors 0270-6474/14/3413768-12$15.00/0.

A visual understanding of optical rotation using corn syrup

NASA Astrophysics Data System (ADS)

Nixon, M.; Hughes, I. G.

2017-07-01

In this paper a visual demonstration of optical rotation is presented, with content appropriate for use in a lecture demonstration as well as quantitative techniques suitable for an undergraduate-laboratory experiment. Linearly polarised lasers of various wavelengths are propagated through a glass tube containing corn syrup. The rotation of the plane of polarisation of the light is visible with the naked eye, making the experiment dramatic and engaging and aiding understanding of the phenomenon of optical rotation. In addition, we present a simple approach to quantitatively analyse data using only equipment commonly found in undergraduate teaching laboratories.

Coordinated Control of Three-Dimensional Components of Smooth Pursuit to Rotating and Translating Textures.

PubMed

Edinger, Janick; Pai, Dinesh K; Spering, Miriam

2017-01-01

The neural control of pursuit eye movements to visual textures that simultaneously translate and rotate has largely been neglected. Here we propose that pursuit of such targets-texture pursuit-is a fully three-dimensional task that utilizes all three degrees of freedom of the eye, including torsion. Head-fixed healthy human adults (n = 8) tracked a translating and rotating random dot pattern, shown on a computer monitor, with their eyes. Horizontal, vertical, and torsional eye positions were recorded with a head-mounted eye tracker. The torsional component of pursuit is a function of the rotation of the texture, aligned with its visual properties. We observed distinct behaviors between those trials in which stimulus rotation was in the same direction as that of a rolling ball ("natural") in comparison to those with the opposite rotation ("unnatural"): Natural rotation enhanced and unnatural rotation reversed torsional velocity during pursuit, as compared to torsion triggered by a nonrotating random dot pattern. Natural rotation also triggered pursuit with a higher horizontal velocity gain and fewer and smaller corrective saccades. Furthermore, we show that horizontal corrective saccades are synchronized with torsional corrective saccades, indicating temporal coupling of horizontal and torsional saccade control. Pursuit eye movements have a torsional component that depends on the visual stimulus. Horizontal and torsional eye movements are separated in the motor periphery. Our findings suggest that translational and rotational motion signals might be coordinated in descending pursuit pathways.

Measurement of electromagnetic tracking error in a navigated breast surgery setup

NASA Astrophysics Data System (ADS)

Harish, Vinyas; Baksh, Aidan; Ungi, Tamas; Lasso, Andras; Baum, Zachary; Gauvin, Gabrielle; Engel, Jay; Rudan, John; Fichtinger, Gabor

2016-03-01

PURPOSE: The measurement of tracking error is crucial to ensure the safety and feasibility of electromagnetically tracked, image-guided procedures. Measurement should occur in a clinical environment because electromagnetic field distortion depends on positioning relative to the field generator and metal objects. However, we could not find an accessible and open-source system for calibration, error measurement, and visualization. We developed such a system and tested it in a navigated breast surgery setup. METHODS: A pointer tool was designed for concurrent electromagnetic and optical tracking. Software modules were developed for automatic calibration of the measurement system, real-time error visualization, and analysis. The system was taken to an operating room to test for field distortion in a navigated breast surgery setup. Positional and rotational electromagnetic tracking errors were then calculated using optical tracking as a ground truth. RESULTS: Our system is quick to set up and can be rapidly deployed. The process from calibration to visualization also only takes a few minutes. Field distortion was measured in the presence of various surgical equipment. Positional and rotational error in a clean field was approximately 0.90 mm and 0.31°. The presence of a surgical table, an electrosurgical cautery, and anesthesia machine increased the error by up to a few tenths of a millimeter and tenth of a degree. CONCLUSION: In a navigated breast surgery setup, measurement and visualization of tracking error defines a safe working area in the presence of surgical equipment. Our system is available as an extension for the open-source 3D Slicer platform.

Cyclic fatigue of ProFile rotary instruments after prolonged clinical use.

PubMed

Gambarini, G

2001-07-01

The purpose of the present study was to evaluate resistance to cyclic fatigue of new and used ProFile Ni-Ti rotary instruments. Used instruments were operated in 10 clinical cases using passive instrumentation and a crown-down preparation technique. Cyclic fatigue testing of new and used engine-driven instruments was then performed with a specific device which allowed the instruments to rotate freely inside a stainless steel artificial canal, whilst maintaining conditions close to the clinical situation. Instruments were rotated until fracture occurred and time to fracture was visually recorded with a chronometer. A significant reduction of rotation time to breakage (life span) was noted between new and used instruments. In all sizes new instruments were significantly more resistant than used ones (two-sample t-test, P < 0.01). No instrument underwent intracanal failure during clinical use. Prolonged clinical use of Ni-Ti engine-driven instruments significantly reduced their cyclic fatigue resistance. Nevertheless, each rotary instrument was successfully operated in up to 10 clinical cases without any intracanal failure.

Visualization of Sliding and Deformation of Orbital Fat During Eye Rotation

PubMed Central

Hötte, Gijsbert J.; Schaafsma, Peter J.; Botha, Charl P.; Wielopolski, Piotr A.; Simonsz, Huibert J.

2016-01-01

Purpose Little is known about the way orbital fat slides and/or deforms during eye movements. We compared two deformation algorithms from a sequence of MRI volumes to visualize this complex behavior. Methods Time-dependent deformation data were derived from motion-MRI volumes using Lucas and Kanade Optical Flow (LK3D) and nonrigid registration (B-splines) deformation algorithms. We compared how these two algorithms performed regarding sliding and deformation in three critical areas: the sclera-fat interface, how the optic nerve moves through the fat, and how the fat is squeezed out under the tendon of a relaxing rectus muscle. The efficacy was validated using identified tissue markers such as the lens and blood vessels in the fat. Results Fat immediately behind the eye followed eye rotation by approximately one-half. This was best visualized using the B-splines technique as it showed less ripping of tissue and less distortion. Orbital fat flowed around the optic nerve during eye rotation. In this case, LK3D provided better visualization as it allowed orbital fat tissue to split. The resolution was insufficient to visualize fat being squeezed out between tendon and sclera. Conclusion B-splines performs better in tracking structures such as the lens, while LK3D allows fat tissue to split as should happen as the optic nerve slides through the fat. Orbital fat follows eye rotation by one-half and flows around the optic nerve during eye rotation. Translational Relevance Visualizing orbital fat deformation and sliding offers the opportunity to accurately locate a region of cicatrization and permit an individualized surgical plan. PMID:27540495

Shoulder-specific outcomes 1 year after nontraumatic full-thickness rotator cuff repair: a systematic literature review and meta-analysis.

PubMed

Gurnani, Navin; van Deurzen, Derek F P; van den Bekerom, Michel P J

2017-10-01

Nontraumatic full-thickness rotator cuff tears are commonly initially treated conservatively. If conservative treatment fails, rotator cuff repair is a viable subsequent option. The objective of the present meta-analysis is to evaluate the shoulder-specific outcomes one year after arthroscopic or mini-open rotator cuff repair of nontraumatic rotator cuff tears. A literature search was conducted in PubMed and EMBASE within the period January 2000 to January 2017. All studies measuring the clinical outcome at 12 months after nontraumatic rotator cuff repair of full-thickness rotator cuff tears were listed. We included 16 randomized controlled trials that met our inclusion criteria with a total of 1.221 shoulders. At 12 months after rotator cuff repair, the mean Constant score had increased 29.5 points; the mean American Shoulder and Elbow Score score increased by 38.6 points; mean Simple Shoulder Test score was 5.6 points; mean University of California Los Angeles score improved by 13.0 points; and finally, mean Visual Analogue Scale score decreased by 4.1 points. Based on this meta-analysis, significant improvements in the shoulder-specific indices are observed 12 months after nontraumatic arthroscopic or mini-open rotator cuff repair.

Electromyographic activity after latissimus dorsi transfer: testing of coactivation as a simple tool to assess latissimus dorsi motor learning.

PubMed

Plath, Johannes E; Seiberl, Wolfgang; Beitzel, Knut; Minzlaff, Philipp; Schwirtz, Ansgar; Imhoff, Andreas B; Buchmann, Stefan

2014-08-01

The purpose of this study was to investigate coactivation (CoA) testing as a clinical tool to monitor motor learning after latissimus dorsi tendon transfer. We evaluated 20 patients clinically with the American Shoulder and Elbow Surgeons (ASES) and University of California-Los Angeles (UCLA) outcomes scores, visual analog scale, active external rotation (aER), and isometric strength testing in abduction and external rotation. Measurements of aER were performed while the latissimus dorsi was activated in its new function of external rotation with concomitant activation (coactivation) of its native functions (adduction and extension). Bilateral surface electromyographic (EMG) activity was recorded during aER measurements and the strength testing procedure (EMG activity ratio: with/without CoA). Patients were divided into two groups (excellent/good vs fair/poor) according to the results of the ASES and UCLA scores. The mean follow-up was 57.8 ± 25.2 months. Subdivided by clinical scores, the superior outcome group lost aER with CoA, whereas the inferior outcome group gained aER (UCLA score: -2.2° ± 7.4° vs +4.3° ± 4.1°; P = .031). Patients with inferior outcomes in the ASES score showed higher latissimus dorsi EMG activity ratios (P = .027), suggesting an inadequate motor learning process. Isometric strength testing revealed that the latissimus dorsi transfer had significantly greater activity compared with the contralateral side (external rotation, P = .008; abduction, P = .006) but did not have comparable strength (external rotation, P = .017; abduction, P = .009). Patients with inferior clinical results were more likely to be dependent on CoA to gain external rotation. Therefore, CoA testing may be used as a tool to evaluate the status of postoperative motor learning after latissimus dorsi transfer. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

Factors affecting healing rates after arthroscopic double-row rotator cuff repair.

PubMed

Tashjian, Robert Z; Hollins, Anthony M; Kim, Hyun-Min; Teefey, Sharlene A; Middleton, William D; Steger-May, Karen; Galatz, Leesa M; Yamaguchi, Ken

2010-12-01

Double-row arthroscopic rotator cuff repairs were developed to improve initial biomechanical strength of repairs to improve healing rates. Despite biomechanical improvements, failure of healing remains a clinical problem. To evaluate the anatomical results after double-row arthroscopic rotator cuff repair with ultrasound to determine postoperative repair integrity and the effect of various factors on tendon healing. Case series; Level of evidence, 4. Forty-eight patients (49 shoulders) who had a complete arthroscopic rotator cuff repair (double-row technique) were evaluated with ultrasound at a minimum of 6 months after surgery. Outcome was evaluated at a minimum of 1-year follow-up with standardized history and physical examination, visual analog scale for pain, active forward elevation, and preoperative and postoperative shoulder scores according to the system of the American Shoulder and Elbow Surgeons and the Simple Shoulder Test. Quantitative strength was measured postoperatively. Ultrasound and physical examinations were performed at a minimum of 6 months after surgery (mean, 16 months; range, 6 to 36 months) and outcome questionnaire evaluations at a minimum of 12 months after surgery (mean, 29 months; range, 12 to 55 months). Of 49 repairs, 25 (51%) were healed. Healing rates were 67% in single-tendon tears (16 of 24 shoulders) and 36% in multitendon tears (9 of 25 shoulders). Older age and longer duration of follow-up were correlated with poorer tendon healing (P < .03). Visual analog scale for pain, active forward elevation, American Shoulder and Elbow Surgeons scores, and Simple Shoulder Test scores all had significant improvement from baseline after repair (P < .0001). Increased age and longer duration of follow-up were associated with lower healing rates after double-row rotator cuff repair. The biological limitation at the repair site, as reflected by the effects of age on healing, appears to be the most important factor influencing tendon healing, even after maximizing repair biomechanical strength with a double-row construct.

Allocentric but not egocentric visual memory difficulties in adults with ADHD may represent cognitive inefficiency.

PubMed

Brown, Franklin C; Roth, Robert M; Katz, Lynda J

2015-08-30

Attention Deficit Hyperactivity Disorder (ADHD) has often been conceptualized as arising executive dysfunctions (e.g., inattention, defective inhibition). However, recent studies suggested that cognitive inefficiency may underlie many ADHD symptoms, according to reaction time and processing speed abnormalities. This study explored whether a non-timed measure of cognitive inefficiency would also be abnormal. A sample of 23 ADHD subjects was compared to 23 controls on a test that included both egocentric and allocentric visual memory subtests. A factor analysis was used to determine which cognitive variables contributed to allocentric visual memory. The ADHD sample performed significantly lower on the allocentric but not egocentric conditions. Allocentric visual memory was not associated with timed, working memory, visual perception, or mental rotation variables. This paper concluded by discussing how these results supported a cognitive inefficiency explanation for some ADHD symptoms, and discussed future research directions. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Student Perceptions of Sectional CT/MRI Use in Teaching Veterinary Anatomy and the Correlation with Visual Spatial Ability: A Student Survey and Mental Rotations Test.

PubMed

Delisser, Peter J; Carwardine, Darren

2017-11-29

Diagnostic imaging technology is becoming more advanced and widely available to veterinary patients with the growing popularity of veterinary-specific computed tomography (CT) and magnetic resonance imaging (MRI). Veterinary students must, therefore, be familiar with these technologies and understand the importance of sound anatomic knowledge for interpretation of the resultant images. Anatomy teaching relies heavily on visual perception of structures and their function. In addition, visual spatial ability (VSA) positively correlates with anatomy test scores. We sought to assess the impact of including more diagnostic imaging, particularly CT/MRI, in the teaching of veterinary anatomy on the students' perceived level of usefulness and ease of understanding content. Finally, we investigated survey answers' relationship to the students' inherent baseline VSA, measured by a standard Mental Rotations Test. Students viewed diagnostic imaging as a useful inclusion that provided clear links to clinical relevance, thus improving the students' perceived benefits in its use. Use of CT and MRI images was not viewed as more beneficial, more relevant, or more useful than the use of radiographs. Furthermore, students felt that the usefulness of CT/MRI inclusion was mitigated by the lack of prior formal instruction on the basics of CT/MRI image generation and interpretation. To be of significantly greater use, addition of learning resources labeling relevant anatomy in tomographical images would improve utility of this novel teaching resource. The present study failed to find any correlation between student perceptions of diagnostic imaging in anatomy teaching and their VSA.

Neurocognitive responses to a single session of static squats with whole body vibration.

PubMed

Amonette, William E; Boyle, Mandy; Psarakis, Maria B; Barker, Jennifer; Dupler, Terry L; Ott, Summer D

2015-01-01

The purpose of this study was to determine if the head accelerations using a common whole body vibration (WBV) exercise protocol acutely reduced neurocognition in healthy subjects. Second, we investigated differential responses to WBV plates with 2 different delivery mechanisms: vertical and rotational vibrations. Twelve healthy subjects (N = 12) volunteered and completed a baseline (BASE) neurocognitive assessment: the Immediate Postconcussion Assessment and Cognitive Test (ImPACT). Subjects then participated in 3 randomized exercise sessions separated by no more than 2 weeks. The exercise sessions consisted of five 2-minute sets of static hip-width stance squats, with the knees positioned at a 45° angle of flexion. The squats were performed with no vibration (control [CON]), with a vertically vibrating plate (vertical vibration [VV]), and with a rotational vibrating plate (rotational vibration [RV]) set to 30 Hz with 4 mm of peak-to-peak displacement. The ImPACT assessments were completed immediately after each exercise session and the composite score for 5 cognitive domains was analyzed: verbal memory, visual memory, visual motor speed, reaction time, and impulse control. Verbal memory scores were unaffected by exercise with or without vibration (p = 0.40). Likewise, visual memory was not different (p = 0.14) after CON, VV, or RV. Significant differences were detected for visual motor speed (p = 0.006); VV was elevated compared with BASE (p = 0.01). There were no significant differences (p = 0.26) in reaction time or impulse control (p = 0.16) after exercise with or without vibration. In healthy individuals, 10 minutes of 30 Hz, 4-mm peak-to-peak displacement vibration exposure with a 45° angle of knee flexion did not negatively affect neurocognition.

Visual Cues Generated during Action Facilitate 14-Month-Old Infants' Mental Rotation

ERIC Educational Resources Information Center

Antrilli, Nick K.; Wang, Su-hua

2016-01-01

Although action experience has been shown to enhance the development of spatial cognition, the mechanism underlying the effects of action is still unclear. The present research examined the role of visual cues generated during action in promoting infants' mental rotation. We sought to clarify the underlying mechanism by decoupling different…

Experimental tests of a superposition hypothesis to explain the relationship between the vestibuloocular reflex and smooth pursuit during horizontal combined eye-head tracking in humans

NASA Technical Reports Server (NTRS)

Huebner, W. P.; Leigh, R. J.; Seidman, S. H.; Thomas, C. W.; Billian, C.; DiScenna, A. O.; Dell'Osso, L. F.

1992-01-01

1. We used a modeling approach to test the hypothesis that, in humans, the smooth pursuit (SP) system provides the primary signal for cancelling the vestibuloocular reflex (VOR) during combined eye-head tracking (CEHT) of a target moving smoothly in the horizontal plane. Separate models for SP and the VOR were developed. The optimal values of parameters of the two models were calculated using measured responses of four subjects to trials of SP and the visually enhanced VOR. After optimal parameter values were specified, each model generated waveforms that accurately reflected the subjects' responses to SP and vestibular stimuli. The models were then combined into a CEHT model wherein the final eye movement command signal was generated as the linear summation of the signals from the SP and VOR pathways. 2. The SP-VOR superposition hypothesis was tested using two types of CEHT stimuli, both of which involved passive rotation of subjects in a vestibular chair. The first stimulus consisted of a "chair brake" or sudden stop of the subject's head during CEHT; the visual target continued to move. The second stimulus consisted of a sudden change from the visually enhanced VOR to CEHT ("delayed target onset" paradigm); as the vestibular chair rotated past the angular position of the stationary visual stimulus, the latter started to move in synchrony with the chair. Data collected during experiments that employed these stimuli were compared quantitatively with predictions made by the CEHT model. 3. During CEHT, when the chair was suddenly and unexpectedly stopped, the eye promptly began to move in the orbit to track the moving target. Initially, gaze velocity did not completely match target velocity, however; this finally occurred approximately 100 ms after the brake onset. The model did predict the prompt onset of eye-in-orbit motion after the brake, but it did not predict that gaze velocity would initially be only approximately 70% of target velocity. One possible explanation for this discrepancy is that VOR gain can be dynamically modulated and, during sustained CEHT, it may assume a lower value. Consequently, during CEHT, a smaller-amplitude SP signal would be needed to cancel the lower-gain VOR. This reduction of the SP signal could account for the attenuated tracking response observed immediately after the brake. We found evidence for the dynamic modulation of VOR gain by noting differences in responses to the onset and offset of head rotation in trials of the visually enhanced VOR.(ABSTRACT TRUNCATED AT 400 WORDS).

Context-dependent olfactory enhancement of optomotor flight control in Drosophila.

PubMed

Chow, Dawnis M; Frye, Mark A

2008-08-01

Sensing and following the chemical plume of food odors is a fundamental challenge faced by many organisms. For flying insects, the task is complicated by wind that distorts the plume and buffets the fly. To maintain an upwind heading, and thus stabilize their orientation in a plume, insects such as flies and moths make use of strong context-specific visual equilibrium reflexes. For example, flying straight requires the regulation of image rotation across the eye, whereas minimizing side-slip and avoiding a collision require regulation of image expansion. In flies, visual rotation stabilizes plume tracking, but rotation and expansion optomotor responses are controlled by separate visual pathways. Are olfactory signals integrated with optomotor responses in a manner dependent upon visual context? We addressed this question by investigating the effect of an attractive food odor on active optomotor flight control. Odorant caused flies both to increase aerodynamic power output and to steer straighter. However, when challenged with wide-field optic flow, odor resulted in enhanced amplitude rotation responses but reduced amplitude expansion responses. For both visual conditions, flies tracked motion signals more closely in odor, an indication of increased saliency. These results suggest a simple search algorithm by which olfactory signals improve the salience of visual stimuli and modify optomotor control in a context-dependent manner, thereby enabling an animal to fly straight up a plume and approach odiferous objects.

Learning a visuomotor rotation: simultaneous visual and proprioceptive information is crucial for visuomotor remapping.

PubMed

Shabbott, Britne A; Sainburg, Robert L

2010-05-01

Visuomotor adaptation is mediated by errors between intended and sensory-detected arm positions. However, it is not clear whether visual-based errors that are shown during the course of motion lead to qualitatively different or more efficient adaptation than errors shown after movement. For instance, continuous visual feedback mediates online error corrections, which may facilitate or inhibit the adaptation process. We addressed this question by manipulating the timing of visual error information and task instructions during a visuomotor adaptation task. Subjects were exposed to a visuomotor rotation, during which they received continuous visual feedback (CF) of hand position with instructions to correct or not correct online errors, or knowledge-of-results (KR), provided as a static hand-path at the end of each trial. Our results showed that all groups improved performance with practice, and that online error corrections were inconsequential to the adaptation process. However, in contrast to the CF groups, the KR group showed relatively small reductions in mean error with practice, increased inter-trial variability during rotation exposure, and more limited generalization across target distances and workspace. Further, although the KR group showed improved performance with practice, after-effects were minimal when the rotation was removed. These findings suggest that simultaneous visual and proprioceptive information is critical in altering neural representations of visuomotor maps, although delayed error information may elicit compensatory strategies to offset perturbations.

Visualisation of the flow at the tip of a high speed axial flow turbine rotor: An assessment of flow visualisation techniques and the requirement of the experimental turbine

NASA Astrophysics Data System (ADS)

Bindon, J.; Alder, D.; Ianovici, I.

1987-11-01

The field of flow visualization has been reviewed and its application to the study of the flow near the tip of an unshrouded axial turbine rotor discussed in detail. The logical conceptualization of experiments which could lead to a final understanding of the flow structure was developed and how this leads to test turbine design philosophy is suggested. The rotor periodicity shed by the stator requires that particle of pulse tracing is needed rather than the more universal continuous streamline trace which arises from a continuous tracer injection at a point in a flow. While the whole field of flow visualization at a rotor tip is demanding because of its very nature, pulse tracking will place a greater demand on the development of new skills and techniques. Since streamline tracking is somewhat more standard, these demands will not be as great. A fundamental choice does however need to be made between the two methods. The suggested experimental turbine should thus, always with the facility of infinitely variable Mach number, model the following: (1) Stationary annular cascade with tip clearance inside a stationary outer endwall; (2) Stationary annular cascade with tip clearance inside a moving endwall; (3) The transfer of flow visualization techniques developed into the rotating frame; (4) Fully rotating rotor with no inlet periodicity; (5) Fully rotating rotor with inlet periodicity.

Combined influence of vergence and eye position on three-dimensional vestibulo-ocular reflex in the monkey.

PubMed

Misslisch, H; Hess, B J M

2002-11-01

This study examined two kinematical features of the rotational vestibulo-ocular reflex (VOR) of the monkey in near vision. First, is there an effect of eye position on the axes of eye rotation during yaw, pitch and roll head rotations when the eyes are converged to fixate near targets? Second, do the three-dimensional positions of the left and right eye during yaw and roll head rotations obey the binocular extension of Listing's law (L2), showing eye position planes that rotate temporally by a quarter as far as the angle of horizontal vergence? Animals fixated near visual targets requiring 17 or 8.5 degrees vergence and placed at straight ahead, 20 degrees up, down, left, or right during yaw, pitch, and roll head rotations at 1 Hz. The 17 degrees vergence experiments were performed both with and without a structured visual background, the 8.5 degrees vergence experiments with a visual background only. A 40 degrees horizontal change in eye position never influenced the axis of eye rotation produced by the VOR during pitch head rotation. Eye position did not affect the VOR eye rotation axes, which stayed aligned with the yaw and roll head rotation axes, when torsional gain was high. If torsional gain was low, eccentric eye positions produced yaw and roll VOR eye rotation axes that tilted somewhat in the directions predicted by Listing's law, i.e., with or opposite to gaze during yaw or roll. These findings were seen in both visual conditions and in both vergence experiments. During yaw and roll head rotations with a 40 degrees vertical change in gaze, torsional eye position followed on average the prediction of L2: the left eye showed counterclockwise (ex-) torsion in down gaze and clockwise (in-) torsion in up gaze and vice versa for the right eye. In other words, the left and right eye's position plane rotated temporally by about a quarter of the horizontal vergence angle. Our results indicate that torsional gain is the central mechanism by which the brain adjusts the retinal image stabilizing function of the VOR both in far and near vision and the three dimensional eye positions during yaw and roll head rotations in near vision follow on average the predictions of L2, a kinematic pattern that is maintained by the saccadic/quick phase system.

Judging sound rotation when listeners and sounds rotate: Sound source localization is a multisystem process.

PubMed

Yost, William A; Zhong, Xuan; Najam, Anbar

2015-11-01

In four experiments listeners were rotated or were stationary. Sounds came from a stationary loudspeaker or rotated from loudspeaker to loudspeaker around an azimuth array. When either sounds or listeners rotate the auditory cues used for sound source localization change, but in the everyday world listeners perceive sound rotation only when sounds rotate not when listeners rotate. In the everyday world sound source locations are referenced to positions in the environment (a world-centric reference system). The auditory cues for sound source location indicate locations relative to the head (a head-centric reference system), not locations relative to the world. This paper deals with a general hypothesis that the world-centric location of sound sources requires the auditory system to have information about auditory cues used for sound source location and cues about head position. The use of visual and vestibular information in determining rotating head position in sound rotation perception was investigated. The experiments show that sound rotation perception when sources and listeners rotate was based on acoustic, visual, and, perhaps, vestibular information. The findings are consistent with the general hypotheses and suggest that sound source localization is not based just on acoustics. It is a multisystem process.

Probing the Relationship between Process of Spatial Problems Solving and Science Learning: An Eye Tracking Approach

ERIC Educational Resources Information Center

Chen, Yi-Chun; Yang, Fang-Ying

2014-01-01

There were two purposes in the study. One was to explore the cognitive activities during spatial problem solving and the other to probe the relationship between spatial ability and science concept learning. Twenty university students participated in the study. The Purdue Visualization of Rotations Test (PVRT) was used to assess the spatial…

Peripheral refraction with eye and head rotation with contact lenses.

PubMed

Lopes-Ferreira, Daniela P; Neves, Helena I F; Faria-Ribeiro, Miguel; Queirós, António; Fernandes, Paulo R B; González-Méijome, José M

2015-04-01

To evaluate the impact of eye and head rotation in the measurement of peripheral refraction with an open-field autorefractometer in myopic eyes wearing two different center-distance designs of multifocal contact lenses (MFCLs). Nineteen right eyes from 19 myopic patients (average central M ± SD = -2.67 ± 1.66 D) aged 20-27 years (mean ± SD = 23.2 ± 3.3 years) were evaluated using a Grand-Seiko autorefractometer. Patients were fitted with one multifocal aspheric center-distance contact lens (Biofinity Multifocal D(®)) and with one multi-concentric MFCL (Acuvue Oasys for Presbyopia). Axial and peripheral refraction were evaluated by eye rotation and by head rotation under naked eye condition and with each MFCL fitted randomly and in independent sessions. For the naked eye, refractive pattern (M, J0 and J45) across the central 60° of the horizontal visual field values did not show significant changes measured by rotating the eye or rotating the head (p > 0.05). Similar results were obtained wearing the Biofinity D, for both testing methods, no obtaining significant differences to M, J0 and J45 values (p > 0.05). For Acuvue Oasys for presbyopia, also no differences were found when comparing measurements obtained by eye and head rotation (p > 0.05). Multivariate analysis did not showed a significant interaction between testing method and lens type neither with measuring locations (MANOVA, p > 0.05). There were significant differences in M and J0 values between naked eyes and each MFCL. Measurements of peripheral refraction by rotating the eye or rotating the head in myopic patients wearing dominant design or multi-concentric multifocal silicone hydrogel contact lens are comparable. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Age-related similarities and differences in monitoring spatial cognition.

PubMed

Ariel, Robert; Moffat, Scott D

2018-05-01

Spatial cognitive performance is impaired in later adulthood but it is unclear whether the metacognitive processes involved in monitoring spatial cognitive performance are also compromised. Inaccurate monitoring could affect whether people choose to engage in tasks that require spatial thinking and also the strategies they use in spatial domains such as navigation. The current experiment examined potential age differences in monitoring spatial cognitive performance in a variety of spatial domains including visual-spatial working memory, spatial orientation, spatial visualization, navigation, and place learning. Younger and older adults completed a 2D mental rotation test, 3D mental rotation test, paper folding test, spatial memory span test, two virtual navigation tasks, and a cognitive mapping test. Participants also made metacognitive judgments of performance (confidence judgments, judgments of learning, or navigation time estimates) on each trial for all spatial tasks. Preference for allocentric or egocentric navigation strategies was also measured. Overall, performance was poorer and confidence in performance was lower for older adults than younger adults. In most spatial domains, the absolute and relative accuracy of metacognitive judgments was equivalent for both age groups. However, age differences in monitoring accuracy (specifically relative accuracy) emerged in spatial tasks involving navigation. Confidence in navigating for a target location also mediated age differences in allocentric navigation strategy use. These findings suggest that with the possible exception of navigation monitoring, spatial cognition may be spared from age-related decline even though spatial cognition itself is impaired in older age.

The development of newborn object recognition in fast and slow visual worlds

PubMed Central

Wood, Justin N.; Wood, Samantha M. W.

2016-01-01

Object recognition is central to perception and cognition. Yet relatively little is known about the environmental factors that cause invariant object recognition to emerge in the newborn brain. Is this ability a hardwired property of vision? Or does the development of invariant object recognition require experience with a particular kind of visual environment? Here, we used a high-throughput controlled-rearing method to examine whether newborn chicks (Gallus gallus) require visual experience with slowly changing objects to develop invariant object recognition abilities. When newborn chicks were raised with a slowly rotating virtual object, the chicks built invariant object representations that generalized across novel viewpoints and rotation speeds. In contrast, when newborn chicks were raised with a virtual object that rotated more quickly, the chicks built viewpoint-specific object representations that failed to generalize to novel viewpoints and rotation speeds. Moreover, there was a direct relationship between the speed of the object and the amount of invariance in the chick's object representation. Thus, visual experience with slowly changing objects plays a critical role in the development of invariant object recognition. These results indicate that invariant object recognition is not a hardwired property of vision, but is learned rapidly when newborns encounter a slowly changing visual world. PMID:27097925

Powder metallurgy Rene 95 rotating turbine engine parts, volume 2

NASA Technical Reports Server (NTRS)

Wilbers, L. G.; Redden, T. K.

1981-01-01

A Rene 95 alloy as-HIP high pressure turbine aft shaft in the CF6-50 engine and a HIP plus forged Rene 95 compressor disk in the CFM56 engine were tested. The CF6-50 engine test was conducted for 1000 C cycles and the CFM56 test for 2000 C cycles. Post test evaluation and analysis of the CF6-50 shaft and the CFM56 compressor disk included visual, fluorescent penetrant, and dimensional inspections. No defects or otherwise discrepant conditions were found. These parts were judged to have performed satisfactorily.

The role of rotational hand movements and general motor ability in children’s mental rotation performance

PubMed Central

Jansen, Petra; Kellner, Jan

2015-01-01

Mental rotation of visual images of body parts and abstract shapes can be influenced by simultaneous motor activity. Children in particular have a strong coupling between motor and cognitive processes. We investigated the influence of a rotational hand movement performed by rotating a knob on mental rotation performance in primary school-age children (N = 83; age range: 7.0–8.3 and 9.0–10.11 years). In addition, we assessed the role of motor ability in this relationship. Boys in the 7- to 8-year-old group were faster when mentally and manually rotating in the same direction than in the opposite direction. For girls and older children this effect was not found. A positive relationship was found between motor ability and accuracy on the mental rotation task: stronger motor ability related to improved mental rotation performance. In both age groups, children with more advanced motor abilities were more likely to adopt motor processes to solve mental rotation tasks if the mental rotation task was primed by a motor task. Our evidence supports the idea that an overlap between motor and visual cognitive processes in children is influenced by motor ability. PMID:26236262

The role of rotational hand movements and general motor ability in children's mental rotation performance.

PubMed

Jansen, Petra; Kellner, Jan

2015-01-01

Mental rotation of visual images of body parts and abstract shapes can be influenced by simultaneous motor activity. Children in particular have a strong coupling between motor and cognitive processes. We investigated the influence of a rotational hand movement performed by rotating a knob on mental rotation performance in primary school-age children (N = 83; age range: 7.0-8.3 and 9.0-10.11 years). In addition, we assessed the role of motor ability in this relationship. Boys in the 7- to 8-year-old group were faster when mentally and manually rotating in the same direction than in the opposite direction. For girls and older children this effect was not found. A positive relationship was found between motor ability and accuracy on the mental rotation task: stronger motor ability related to improved mental rotation performance. In both age groups, children with more advanced motor abilities were more likely to adopt motor processes to solve mental rotation tasks if the mental rotation task was primed by a motor task. Our evidence supports the idea that an overlap between motor and visual cognitive processes in children is influenced by motor ability.

Training in Mental Rotation and Spatial Visualization and Its Impact on Orthographic Drawing Performance

ERIC Educational Resources Information Center

Samsudin, Khairulanuar; Rafi, Ahmad; Hanif, Abd Samad

2011-01-01

This paper reports the findings from an experimental study based on the pretest posttest research design that studied mental rotation (MR) and spatial visualization (SV) training outcomes and their impact on orthographic drawing performance. The sample of the study comprised 98 secondary school students (36 girls, 62 boys, Mage = 15.5 years, age…

Visual Form Perception Can Be a Cognitive Correlate of Lower Level Math Categories for Teenagers

PubMed Central

Cui, Jiaxin; Zhang, Yiyun; Cheng, Dazhi; Li, Dawei; Zhou, Xinlin

2017-01-01

Numerous studies have assessed the cognitive correlates of performance in mathematics, but little research has been conducted to systematically examine the relations between visual perception as the starting point of visuospatial processing and typical mathematical performance. In the current study, we recruited 223 seventh graders to perform a visual form perception task (figure matching), numerosity comparison, digit comparison, exact computation, approximate computation, and curriculum-based mathematical achievement tests. Results showed that, after controlling for gender, age, and five general cognitive processes (choice reaction time, visual tracing, mental rotation, spatial working memory, and non-verbal matrices reasoning), visual form perception had unique contributions to numerosity comparison, digit comparison, and exact computation, but had no significant relation with approximate computation or curriculum-based mathematical achievement. These results suggest that visual form perception is an important independent cognitive correlate of lower level math categories, including the approximate number system, digit comparison, and exact computation. PMID:28824513

An immediate effect of axial neck rotation training with real time visual feedback using a smartphone inclinometer on improvement in axial neck rotation function.

PubMed

Park, Kyue-Nam; Kwon, Oh-Yun; Kim, Si-Hyun; Jeon, In-Cheol

2017-03-01

The purpose of this study was to compare the immediate effects of axial neck rotation training (Axi-NRT) with and without real-time visual feedback (VF) using a smartphone inclinometer on the range of motion (ROM) for axial neck rotation and the onset of compensatory neck lateral bending and extension during active neck rotation. Twenty participants with restricted ROM for neck rotation but no neck pain (21.1 ± 1.6 years and 8 males, 12 females) were recruited for Axi-NRT with VF, and twenty age- and gender-matched participants with restricted ROM for neck rotation were recruited for Axi-NRT without VF. Changes in ROM for neck rotation and the onset time of compensatory neck movement during active neck rotation were measured using an electromagnetic tracking system. Axi-NRT with VF was more effective in increasing ROM for neck rotation and decreasing and delaying the onset of compensatory neck movements during active neck rotation compared with Axi-NRT without VF. Repeated Axi-NRT using VF is useful to educate participants in maintaining the axis of the cervical spine and to increase ROM for axial neck rotation with less compensatory neck motion in participants with a restricted range of neck rotations.

Think Spatial: The Representation in Mental Rotation Is Nonvisual

ERIC Educational Resources Information Center

Liesefeld, Heinrich R.; Zimmer, Hubert D.

2013-01-01

For mental rotation, introspection, theories, and interpretations of experimental results imply a certain type of mental representation, namely, visual mental images. Characteristics of the rotated representation can be examined by measuring the influence of stimulus characteristics on rotational speed. If the amount of a given type of information…

Relation between perception of vertical axis rotation and vestibulo-ocular reflex symmetry

NASA Technical Reports Server (NTRS)

Peterka, Robert J.; Benolken, Martha S.

1991-01-01

Subjects seated in a vertical axis rotation chair controlled their rotational velocity by adjusting a potentiometer. Their goal was to null out pseudorandom rotational perturbations in order to remain perceptually stationary. Most subjects showed a slow linear drift of velocity (a constant acceleration) to one side when they were deprived of an earth-fixed visual reference. The amplitude and direction of this drift can be considered a measure of a static bias in the subject's perception of rotation. The presence of a perceptual bias is consistent with a small, constant imbalance of vestibular function which could be of either central or peripheral origin. Deviations from perfect vestibulocular reflex (VOR) symmetry are also assumed to be related to imbalances in either peripheral or central vestibular function. Researchers looked for correlations between perceptual bias and various measures of vestibular reflex symmetry that might suggest a common source for both reflective and perceptual imbalances. No correlations were found. Measurement errors could not account for these results since repeated tests on the same subjects of both perceptual bias and VOR symmetry were well correlated.

Kinematics of Visually-Guided Eye Movements

PubMed Central

Hess, Bernhard J. M.; Thomassen, Jakob S.

2014-01-01

One of the hallmarks of an eye movement that follows Listing’s law is the half-angle rule that says that the angular velocity of the eye tilts by half the angle of eccentricity of the line of sight relative to primary eye position. Since all visually-guided eye movements in the regime of far viewing follow Listing’s law (with the head still and upright), the question about its origin is of considerable importance. Here, we provide theoretical and experimental evidence that Listing’s law results from a unique motor strategy that allows minimizing ocular torsion while smoothly tracking objects of interest along any path in visual space. The strategy consists in compounding conventional ocular rotations in meridian planes, that is in horizontal, vertical and oblique directions (which are all torsion-free) with small linear displacements of the eye in the frontal plane. Such compound rotation-displacements of the eye can explain the kinematic paradox that the fixation point may rotate in one plane while the eye rotates in other planes. Its unique signature is the half-angle law in the position domain, which means that the rotation plane of the eye tilts by half-the angle of gaze eccentricity. We show that this law does not readily generalize to the velocity domain of visually-guided eye movements because the angular eye velocity is the sum of two terms, one associated with rotations in meridian planes and one associated with displacements of the eye in the frontal plane. While the first term does not depend on eye position the second term does depend on eye position. We show that compounded rotation - displacements perfectly predict the average smooth kinematics of the eye during steady- state pursuit in both the position and velocity domain. PMID:24751602

Spatiotopic coding during dynamic head tilt

PubMed Central

Turi, Marco; Burr, David C.

2016-01-01

Humans maintain a stable representation of the visual world effortlessly, despite constant movements of the eyes, head, and body, across multiple planes. Whereas visual stability in the face of saccadic eye movements has been intensely researched, fewer studies have investigated retinal image transformations induced by head movements, especially in the frontal plane. Unlike head rotations in the horizontal and sagittal planes, tilting the head in the frontal plane is only partially counteracted by torsional eye movements and consequently induces a distortion of the retinal image to which we seem to be completely oblivious. One possible mechanism aiding perceptual stability is an active reconstruction of a spatiotopic map of the visual world, anchored in allocentric coordinates. To explore this possibility, we measured the positional motion aftereffect (PMAE; the apparent change in position after adaptation to motion) with head tilts of ∼42° between adaptation and test (to dissociate retinal from allocentric coordinates). The aftereffect was shown to have both a retinotopic and spatiotopic component. When tested with unpatterned Gaussian blobs rather than sinusoidal grating stimuli, the retinotopic component was greatly reduced, whereas the spatiotopic component remained. The results suggest that perceptual stability may be maintained at least partially through mechanisms involving spatiotopic coding. NEW & NOTEWORTHY Given that spatiotopic coding could play a key role in maintaining visual stability, we look for evidence of spatiotopic coding after retinal image transformations caused by head tilt. To this end, we measure the strength of the positional motion aftereffect (PMAE; previously shown to be largely spatiotopic after saccades) after large head tilts. We find that, as with eye movements, the spatial selectivity of the PMAE has a large spatiotopic component after head rotation. PMID:27903636

Mental Rotation of Tactical Instruction Displays Affects Information Processing Demand and Execution Accuracy in Basketball

ERIC Educational Resources Information Center

Koopmann, Till; Steggemann-Weinrich, Yvonne; Baumeister, Jochen; Krause, Daniel

2017-01-01

Purpose: In sports games, coaches often use tactic boards to present tactical instructions during time-outs (e.g., 20 s to 60 s in basketball). Instructions should be presented in a way that enables fast and errorless information processing for the players. The aim of this study was to test the effect of different orientations of visual tactical…

Hypothesis Support Mechanism for Mid-Level Visual Pattern Recognition

NASA Technical Reports Server (NTRS)

Amador, Jose J (Inventor)

2007-01-01

A method of mid-level pattern recognition provides for a pose invariant Hough Transform by parametrizing pairs of points in a pattern with respect to at least two reference points, thereby providing a parameter table that is scale- or rotation-invariant. A corresponding inverse transform may be applied to test hypothesized matches in an image and a distance transform utilized to quantify the level of match.

A Comparison of the Effects of Depth Rotation on Visual and Haptic Three-Dimensional Object Recognition

ERIC Educational Resources Information Center

Lawson, Rebecca

2009-01-01

A sequential matching task was used to compare how the difficulty of shape discrimination influences the achievement of object constancy for depth rotations across haptic and visual object recognition. Stimuli were nameable, 3-dimensional plastic models of familiar objects (e.g., bed, chair) and morphs midway between these endpoint shapes (e.g., a…

Awareness of Sensorimotor Adaptation to Visual Rotations of Different Size

PubMed Central

Werner, Susen; van Aken, Bernice C.; Hulst, Thomas; Frens, Maarten A.; van der Geest, Jos N.; Strüder, Heiko K.; Donchin, Opher

2015-01-01

Previous studies on sensorimotor adaptation revealed no awareness of the nature of the perturbation after adaptation to an abrupt 30° rotation of visual feedback or after adaptation to gradually introduced perturbations. Whether the degree of awareness depends on the magnitude of the perturbation, though, has as yet not been tested. Instead of using questionnaires, as was often done in previous work, the present study used a process dissociation procedure to measure awareness and unawareness. A naïve, implicit group and a group of subjects using explicit strategies adapted to 20°, 40° and 60° cursor rotations in different adaptation blocks that were each followed by determination of awareness and unawareness indices. The awareness index differed between groups and increased from 20° to 60° adaptation. In contrast, there was no group difference for the unawareness index, but it also depended on the size of the rotation. Early adaptation varied between groups and correlated with awareness: The more awareness a participant had developed the more the person adapted in the beginning of the adaptation block. In addition, there was a significant group difference for savings but it did not correlate with awareness. Our findings suggest that awareness depends on perturbation size and that aware and strategic processes are differentially involved during adaptation and savings. Moreover, the use of the process dissociation procedure opens the opportunity to determine awareness and unawareness indices in future sensorimotor adaptation research. PMID:25894396

Mental rotation of tactile stimuli: using directional haptic cues in mobile devices.

PubMed

Gleeson, Brian T; Provancher, William R

2013-01-01

Haptic interfaces have the potential to enrich users' interactions with mobile devices and convey information without burdening the user's visual or auditory attention. Haptic stimuli with directional content, for example, navigational cues, may be difficult to use in handheld applications; the user's hand, where the cues are delivered, may not be aligned with the world, where the cues are to be interpreted. In such a case, the user would be required to mentally transform the stimuli between different reference frames. We examine the mental rotation of directional haptic stimuli in three experiments, investigating: 1) users' intuitive interpretation of rotated stimuli, 2) mental rotation of haptic stimuli about a single axis, and 3) rotation about multiple axes and the effects of specific hand poses and joint rotations. We conclude that directional haptic stimuli are suitable for use in mobile applications, although users do not naturally interpret rotated stimuli in any one universal way. We find evidence of cognitive processes involving the rotation of analog, spatial representations and discuss how our results fit into the larger body of mental rotation research. For small angles (e.g., less than 40 degree), these mental rotations come at little cost, but rotations with larger misalignment angles impact user performance. When considering the design of a handheld haptic device, our results indicate that hand pose must be carefully considered, as certain poses increase the difficulty of stimulus interpretation. Generally, all tested joint rotations impact task difficulty, but finger flexion and wrist rotation interact to greatly increase the cost of stimulus interpretation; such hand poses should be avoided when designing a haptic interface.

Vortex flows in the solar chromosphere. I. Automatic detection method

NASA Astrophysics Data System (ADS)

Kato, Y.; Wedemeyer, S.

2017-05-01

Solar "magnetic tornadoes" are produced by rotating magnetic field structures that extend from the upper convection zone and the photosphere to the corona of the Sun. Recent studies show that these kinds of rotating features are an integral part of atmospheric dynamics and occur on a large range of spatial scales. A systematic statistical study of magnetic tornadoes is a necessary next step towards understanding their formation and their role in mass and energy transport in the solar atmosphere. For this purpose, we develop a new automatic detection method for chromospheric swirls, meaning the observable signature of solar tornadoes or, more generally, chromospheric vortex flows and rotating motions. Unlike existing studies that rely on visual inspections, our new method combines a line integral convolution (LIC) imaging technique and a scalar quantity that represents a vortex flow on a two-dimensional plane. We have tested two detection algorithms, based on the enhanced vorticity and vorticity strength quantities, by applying them to three-dimensional numerical simulations of the solar atmosphere with CO5BOLD. We conclude that the vorticity strength method is superior compared to the enhanced vorticity method in all aspects. Applying the method to a numerical simulation of the solar atmosphere reveals very abundant small-scale, short-lived chromospheric vortex flows that have not been found previously by visual inspection.

Like a rolling stone: naturalistic visual kinematics facilitate tracking eye movements.

PubMed

Souto, David; Kerzel, Dirk

2013-02-06

Newtonian physics constrains object kinematics in the real world. We asked whether eye movements towards tracked objects depend on their compliance with those constraints. In particular, the force of gravity constrains round objects to roll on the ground with a particular rotational and translational motion. We measured tracking eye movements towards rolling objects. We found that objects with rotational and translational motion that was congruent with an object rolling on the ground elicited faster tracking eye movements during pursuit initiation than incongruent stimuli. Relative to a condition without rotational component, we compared objects with this motion with a condition in which there was no rotational component, we essentially obtained benefits of congruence, and, to a lesser extent, costs from incongruence. Anticipatory pursuit responses showed no congruence effect, suggesting that the effect is based on visually-driven predictions, not on velocity storage. We suggest that the eye movement system incorporates information about object kinematics acquired by a lifetime of experience with visual stimuli obeying the laws of Newtonian physics.

The effects of leading edge modifications on the post-stall characteristics of wings

NASA Technical Reports Server (NTRS)

Winkelmann, A. E.; Barlow, J. B.; Saini, J. K.; Anderson, J. D., Jr.; Jones, E.

1980-01-01

An investigation of the effects of leading edge modifications on the post-stall characteristics of two rectangular planform wings in a series of low speed wind tunnel tests is presented. Abrupt discontinuities in the leading edge shape of the wings were produced by placing a nose glove over a portion of the span or by deflecting sections of a segmented leading edge flap. Six component balance data, oil flow visualization photographs, and pressure distribution measurements were obtained, and tests made to study the development of flow separation at stall on small scale planform wing models. Results of oil flow visualization tests at and beyond stall showed the formation of counter-rotating swirl patterns on the upper surface of the '2-D' and '3-D' wings, and results of a numerical lifting line technique applied to wings with leading edge modifications are included.

Directional plasticity rapidly improves 3D vestibulo-ocular reflex alignment in monkeys using a multichannel vestibular prosthesis.

PubMed

Dai, Chenkai; Fridman, Gene Y; Chiang, Bryce; Rahman, Mehdi A; Ahn, Joong Ho; Davidovics, Natan S; Della Santina, Charles C

2013-12-01

Bilateral loss of vestibular sensation can be disabling. We have shown that a multichannel vestibular prosthesis (MVP) can partly restore vestibular sensation as evidenced by improvements in the 3-dimensional angular vestibulo-ocular reflex (3D VOR). However, a key challenge is to minimize misalignment between the axes of eye and head rotation, which is apparently caused by current spread beyond each electrode's targeted nerve branch. We recently reported that rodents wearing a MVP markedly improve 3D VOR alignment during the first week after MVP activation, probably through the same central nervous system adaptive mechanisms that mediate cross-axis adaptation over time in normal individuals wearing prisms that cause visual scene movement about an axis different than the axis of head rotation. We hypothesized that rhesus monkeys would exhibit similar improvements with continuous prosthetic stimulation over time. We created bilateral vestibular deficiency in four rhesus monkeys via intratympanic injection of gentamicin. A MVP was mounted to the cranium, and eye movements in response to whole-body passive rotation in darkness were measured repeatedly over 1 week of continuous head motion-modulated prosthetic electrical stimulation. 3D VOR responses to whole-body rotations about each semicircular canal axis were measured on days 1, 3, and 7 of chronic stimulation. Horizontal VOR gain during 1 Hz, 50 °/s peak whole-body rotations before the prosthesis was turned on was <0.1, which is profoundly below normal (0.94 ± 0.12). On stimulation day 1, VOR gain was 0.4-0.8, but the axis of observed eye movements aligned poorly with head rotation (misalignment range ∼30-40 °). Substantial improvement of axis misalignment was observed after 7 days of continuous motion-modulated prosthetic stimulation under normal diurnal lighting. Similar improvements were noted for all animals, all three axes of rotation tested, for all sinusoidal frequencies tested (0.05-5 Hz), and for high-acceleration transient rotations. VOR asymmetry changes did not reach statistical significance, although they did trend toward slight improvement over time. Prior studies had already shown that directional plasticity reduces misalignment when a subject with normal labyrinths views abnormal visual scene movement. Our results show that the converse is also true: individuals receiving misoriented vestibular sensation under normal viewing conditions rapidly adapt to restore a well-aligned 3D VOR. Considering the similarity of VOR physiology across primate species, similar effects are likely to occur in humans using a MVP to treat bilateral vestibular deficiency.

A visual servo-based teleoperation robot system for closed diaphyseal fracture reduction.

PubMed

Li, Changsheng; Wang, Tianmiao; Hu, Lei; Zhang, Lihai; Du, Hailong; Zhao, Lu; Wang, Lifeng; Tang, Peifu

2015-09-01

Common fracture treatments include open reduction and intramedullary nailing technology. However, these methods have disadvantages such as intraoperative X-ray radiation, delayed union or nonunion and postoperative rotation. Robots provide a novel solution to the aforementioned problems while posing new challenges. Against this scientific background, we develop a visual servo-based teleoperation robot system. In this article, we present a robot system, analyze the visual servo-based control system in detail and develop path planning for fracture reduction, inverse kinematics, and output forces of the reduction mechanism. A series of experimental tests is conducted on a bone model and an animal bone. The experimental results demonstrate the feasibility of the robot system. The robot system uses preoperative computed tomography data to realize high precision and perform minimally invasive teleoperation for fracture reduction via the visual servo-based control system while protecting surgeons from radiation. © IMechE 2015.

Syndesmotic fixation in supination-external rotation ankle fractures: a prospective randomized study.

PubMed

Pakarinen, Harri J; Flinkkilä, Tapio E; Ohtonen, Pasi P; Hyvönen, Pekka H; Lakovaara, Martti T; Leppilahti, Juhana I; Ristiniemi, Jukka Y

2011-12-01

This study was designed to assess whether transfixion of an unstable syndesmosis is necessary in supination-external rotation (Lauge-Hansen SE/Weber B)-type ankle fractures. A prospective study of 140 patients with unilateral Lauge-Hansen supination-external rotation type 4 ankle fractures was done. After bony fixation, the 7.5-Nm standardized external rotation (ER) stress test for both ankles was performed under fluoroscopy. A positive stress examination was defined as a difference of more than 2 mm side-to-side in the tibiotalar or tibiofibular clear spaces on mortise radiographs. If the stress test was positive, the patient was randomized to either syndesmotic transfixion with 3.5-mm tricortical screws or no syndesmotic fixation. Clinical outcome was assessed using the Olerud-Molander scoring system, RAND 36-Item Health Survey, and Visual Analogue Scale (VAS) to measure pain and function after a minimum 1-year of followup. Twenty four (17%) of 140 patients had positive standardized 7.5-Nm ER stress tests after malleolar fixation. The stress view was positive three times on tibiotalar clear space, seven on tibiofibular clear space, and 14 times on both tibiotalar and tibiofibular clear spaces. There was no significant difference between the two randomization groups with regards to Olerud-Molander functional score, VAS scale measuring pain and function, or RAND 36-Item Health Survey pain or physical function at 1 year. Relevant syndesmotic injuries are rare in supination-external rotation ankle fractures, and syndesmotic transfixion with a screw did not influence the functional outcome or pain after the 1-year followup compared with no fixation.

Integrating visual learning within a model-based ATR system

NASA Astrophysics Data System (ADS)

Carlotto, Mark; Nebrich, Mark

2017-05-01

Automatic target recognition (ATR) systems, like human photo-interpreters, rely on a variety of visual information for detecting, classifying, and identifying manmade objects in aerial imagery. We describe the integration of a visual learning component into the Image Data Conditioner (IDC) for target/clutter and other visual classification tasks. The component is based on an implementation of a model of the visual cortex developed by Serre, Wolf, and Poggio. Visual learning in an ATR context requires the ability to recognize objects independent of location, scale, and rotation. Our method uses IDC to extract, rotate, and scale image chips at candidate target locations. A bootstrap learning method effectively extends the operation of the classifier beyond the training set and provides a measure of confidence. We show how the classifier can be used to learn other features that are difficult to compute from imagery such as target direction, and to assess the performance of the visual learning process itself.

Mental Rotation, Pictured Rotation, and Tandem Rotation in Depth

DTIC Science & Technology

1997-01-01

field. Such an explanation by natural geometry conflates visual comparison with physical measurement. This application of geometry is called natural in...the theory of vision parasitic on geometry: it is unclear what could be meant by a ’mental operation of rotation’, except by reference to physical ...operation, a mental analogue of the physical operation of rotation in space. Since then the story of mental rotation has become far more complicated

Three-dimensional organization of vestibular related eye movements to rotational motion in pigeons

NASA Technical Reports Server (NTRS)

Dickman, J. D.; Beyer, M.; Hess, B. J.

2000-01-01

During rotational motions, compensatory eye movement adjustments must continually occur in order to maintain objects of visual interest as stable images on the retina. In the present study, the three-dimensional organization of the vestibulo-ocular reflex in pigeons was quantitatively examined. Rotations about different head axes produced horizontal, vertical, and torsional eye movements, whose component magnitude was dependent upon the cosine of the stimulus axis relative to the animal's visual axis. Thus, the three-dimensional organization of the VOR in pigeons appears to be compensatory for any direction of head rotation. Frequency responses of the horizontal, vertical, and torsional slow phase components exhibited high pass filter properties with dominant time constants of approximately 3 s.

The influence of target angular velocity on visual latency difference determined using the rotating Pulfrich effect.

PubMed

Nickalls, R W

1996-09-01

Visual latency difference was determined directly in normal volunteers, using the rotating Pulfrich technique described by Nickalls [Vision Research, 26, 367-372 (1986)]. Subjects fixated a black vertical rod rotating clockwise on a horizontal turntable turning with constant angular velocity (16.6,33.3 or 44.7 revs/min) with a neutral density filter (OD 0.7 or 1.5) in front of the right eye. For all subjects the latency difference associated with the 1.5 OD filter was significantly greater (P < 0.001) with the rod rotating at 16.6 rev/min than at 33.3 revs/min. The existence of an inverse relationship between latency difference and angular velocity is hypothesized.

A Biologically Plausible Transform for Visual Recognition that is Invariant to Translation, Scale, and Rotation.

PubMed

Sountsov, Pavel; Santucci, David M; Lisman, John E

2011-01-01

Visual object recognition occurs easily despite differences in position, size, and rotation of the object, but the neural mechanisms responsible for this invariance are not known. We have found a set of transforms that achieve invariance in a neurally plausible way. We find that a transform based on local spatial frequency analysis of oriented segments and on logarithmic mapping, when applied twice in an iterative fashion, produces an output image that is unique to the object and that remains constant as the input image is shifted, scaled, or rotated.

A Biologically Plausible Transform for Visual Recognition that is Invariant to Translation, Scale, and Rotation

PubMed Central

Sountsov, Pavel; Santucci, David M.; Lisman, John E.

2011-01-01

Visual object recognition occurs easily despite differences in position, size, and rotation of the object, but the neural mechanisms responsible for this invariance are not known. We have found a set of transforms that achieve invariance in a neurally plausible way. We find that a transform based on local spatial frequency analysis of oriented segments and on logarithmic mapping, when applied twice in an iterative fashion, produces an output image that is unique to the object and that remains constant as the input image is shifted, scaled, or rotated. PMID:22125522

Eye-Hand Coordination during Visuomotor Adaptation with Different Rotation Angles: Effects of Terminal Visual Feedback

PubMed Central

Rand, Miya K.; Rentsch, Sebastian

2016-01-01

This study examined adaptive changes of eye-hand coordination during a visuomotor rotation task under the use of terminal visual feedback. Young adults made reaching movements to targets on a digitizer while looking at targets on a monitor where the rotated feedback (a cursor) of hand movements appeared after each movement. Three rotation angles (30°, 75° and 150°) were examined in three groups in order to vary the task difficulty. The results showed that the 30° group gradually reduced direction errors of reaching with practice and adapted well to the visuomotor rotation. The 75° group made large direction errors of reaching, and the 150° group applied a 180° reversal shift from early practice. The 75°and 150° groups, however, overcompensated the respective rotations at the end of practice. Despite these group differences in adaptive changes of reaching, all groups gradually adapted gaze directions prior to reaching from the target area to the areas related to the final positions of reaching during the course of practice. The adaptive changes of both hand and eye movements in all groups mainly reflected adjustments of movement directions based on explicit knowledge of the applied rotation acquired through practice. Only the 30° group showed small implicit adaptation in both effectors. The results suggest that by adapting gaze directions from the target to the final position of reaching based on explicit knowledge of the visuomotor rotation, the oculomotor system supports the limb-motor system to make precise preplanned adjustments of reaching directions during learning of visuomotor rotation under terminal visual feedback. PMID:27812093

The effects of golf training in patients with stroke: a pilot study.

PubMed

Schachten, Tobias; Jansen, Petra

2015-05-01

Stroke is the most common neurological disease and the primary cause of lifelong disability in industrialized countries. Because of this it is important to investigate any kind of successful therapy. From the 24 recruited stroke patients who were between 23 and 72 years old, 14 patients were separated either in a golf training group (EG), or a social communication meeting (CG). Both groups met for one hour sessions, twice a week, for ten weeks. All participants completed assessment tests before and after the experimental period: cognitive tests measuring attention (Go/No-Go task), visual-spatial memory (Block-Tapping test) and mental rotation performance (MRT); a balance test (Berg Balance Scale), and an emotional well-being test (CES-D-Scale). The results show that both groups improved in the CES Scale, the block-tapping test and the balance test. In addition, stroke patients who received a golf training showed a significant improvement in the MRT comparing to the control group (CG). It is indicated that golf training can improve visual imagery ability in stroke patients, even late after stroke.

Improved Visualization of Intracranial Vessels with Intraoperative Coregistration of Rotational Digital Subtraction Angiography and Intraoperative 3D Ultrasound

PubMed Central

Podlesek, Dino; Meyer, Tobias; Morgenstern, Ute; Schackert, Gabriele; Kirsch, Matthias

2015-01-01

Introduction Ultrasound can visualize and update the vessel status in real time during cerebral vascular surgery. We studied the depiction of parent vessels and aneurysms with a high-resolution 3D intraoperative ultrasound imaging system during aneurysm clipping using rotational digital subtraction angiography as a reference. Methods We analyzed 3D intraoperative ultrasound in 39 patients with cerebral aneurysms to visualize the aneurysm intraoperatively and the nearby vascular tree before and after clipping. Simultaneous coregistration of preoperative subtraction angiography data with 3D intraoperative ultrasound was performed to verify the anatomical assignment. Results Intraoperative ultrasound detected 35 of 43 aneurysms (81%) in 39 patients. Thirty-nine intraoperative ultrasound measurements were matched with rotational digital subtraction angiography and were successfully reconstructed during the procedure. In 7 patients, the aneurysm was partially visualized by 3D-ioUS or was not in field of view. Post-clipping intraoperative ultrasound was obtained in 26 and successfully reconstructed in 18 patients (69%) despite clip related artefacts. The overlap between 3D-ioUS aneurysm volume and preoperative rDSA aneurysm volume resulted in a mean accuracy of 0.71 (Dice coefficient). Conclusions Intraoperative coregistration of 3D intraoperative ultrasound data with preoperative rotational digital subtraction angiography is possible with high accuracy. It allows the immediate visualization of vessels beyond the microscopic field, as well as parallel assessment of blood velocity, aneurysm and vascular tree configuration. Although spatial resolution is lower than for standard angiography, the method provides an excellent vascular overview, advantageous interpretation of 3D-ioUS and immediate intraoperative feedback of the vascular status. A prerequisite for understanding vascular intraoperative ultrasound is image quality and a successful match with preoperative rotational digital subtraction angiography. PMID:25803318

Improved visualization of intracranial vessels with intraoperative coregistration of rotational digital subtraction angiography and intraoperative 3D ultrasound.

PubMed

Podlesek, Dino; Meyer, Tobias; Morgenstern, Ute; Schackert, Gabriele; Kirsch, Matthias

2015-01-01

Ultrasound can visualize and update the vessel status in real time during cerebral vascular surgery. We studied the depiction of parent vessels and aneurysms with a high-resolution 3D intraoperative ultrasound imaging system during aneurysm clipping using rotational digital subtraction angiography as a reference. We analyzed 3D intraoperative ultrasound in 39 patients with cerebral aneurysms to visualize the aneurysm intraoperatively and the nearby vascular tree before and after clipping. Simultaneous coregistration of preoperative subtraction angiography data with 3D intraoperative ultrasound was performed to verify the anatomical assignment. Intraoperative ultrasound detected 35 of 43 aneurysms (81%) in 39 patients. Thirty-nine intraoperative ultrasound measurements were matched with rotational digital subtraction angiography and were successfully reconstructed during the procedure. In 7 patients, the aneurysm was partially visualized by 3D-ioUS or was not in field of view. Post-clipping intraoperative ultrasound was obtained in 26 and successfully reconstructed in 18 patients (69%) despite clip related artefacts. The overlap between 3D-ioUS aneurysm volume and preoperative rDSA aneurysm volume resulted in a mean accuracy of 0.71 (Dice coefficient). Intraoperative coregistration of 3D intraoperative ultrasound data with preoperative rotational digital subtraction angiography is possible with high accuracy. It allows the immediate visualization of vessels beyond the microscopic field, as well as parallel assessment of blood velocity, aneurysm and vascular tree configuration. Although spatial resolution is lower than for standard angiography, the method provides an excellent vascular overview, advantageous interpretation of 3D-ioUS and immediate intraoperative feedback of the vascular status. A prerequisite for understanding vascular intraoperative ultrasound is image quality and a successful match with preoperative rotational digital subtraction angiography.

Continuous visual field motion impacts the postural responses of older and younger women during and after support surface tilt

PubMed Central

Lauer, Richard T.; Keshner, Emily A.

2011-01-01

The effect of continuous visual flow on the ability to regain and maintain postural orientation was examined. Fourteen young (20–39 years old) and 14 older women (60–79 years old) stood quietly during 3° (30°/s) dorsiflexion tilt of the support surface combined with 30° and 45°/s upward or downward pitch rotations of the visual field. The support surface was held tilted for 30 s and then returned to neutral over a 30-s period while the visual field continued to rotate. Segmental displacement and bilateral tibialis anterior and gastrocnemius muscle EMG responses were recorded. Continuous wavelet transforms were calculated for each muscle EMG response. An instantaneous mean frequency curve (IMNF) of muscle activity, center of mass (COM), center of pressure (COP), and angular excursion at the hip and ankle were used in a functional principal component analysis (fPCA). Functional component weights were calculated and compared with mixed model repeated measures ANOVAs. The fPCA revealed greatest mathematical differences in COM and COP responses between groups or conditions during the period that the platform transitioned from the sustained tilt to a return to neutral position. Muscle EMG responses differed most in the period following support surface tilt indicating that muscle activity increased to support stabilization against the visual flow. Older women exhibited significantly larger COM and COP responses in the direction of visual field motion and less muscle modulation when the platform returned to neutral than younger women. Results on a Rod and Frame test indicated that older women were significantly more visually dependent than the younger women. We concluded that a stiffer body combined with heightened visual sensitivity in older women critically interferes with their ability to counteract posturally destabilizing environments. PMID:21479659

Influence of combined visual and vestibular cues on human perception and control of horizontal rotation

NASA Technical Reports Server (NTRS)

Zacharias, G. L.; Young, L. R.

1981-01-01

Measurements are made of manual control performance in the closed-loop task of nulling perceived self-rotation velocity about an earth-vertical axis. Self-velocity estimation is modeled as a function of the simultaneous presentation of vestibular and peripheral visual field motion cues. Based on measured low-frequency operator behavior in three visual field environments, a parallel channel linear model is proposed which has separate visual and vestibular pathways summing in a complementary manner. A dual-input describing function analysis supports the complementary model; vestibular cues dominate sensation at higher frequencies. The describing function model is extended by the proposal of a nonlinear cue conflict model, in which cue weighting depends on the level of agreement between visual and vestibular cues.

Astronaut Owen Garriott - Test Subject - Human Vestibular Function Experiment

NASA Image and Video Library

1973-08-09

S73-34171 (9 Aug. 1973) --- Scientist-astronaut Owen K. Garriott, Skylab 3 science pilot, serves as test subject for the Skylab ?Human Vestibular Function? M131 Experiment, as seen in this photographic reproduction taken from a television transmission made by a color TV camera aboard the Skylab space station in Earth orbit. The objectives of the Skylab M131 experiment are to obtain data pertinent to establishing the validity of measurements of specific behavioral/physiological responses influenced by vestibular activity under one-g and zero-g conditions; to determine man?s adaptability to unusual vestibular conditions and predict habitability of future spacecraft conditions involving reduced gravity and Coriollis forces; and to measure the accuracy and variability in man?s judgment of spatial coordinates based on atypical gravity receptor cues and inadequate visual cures. Dr. Garriott is seated in the experiment?s litter chair which can rotate the test subject at predetermined rotational velocity or programmed acceleration/decelerational profile. Photo credit: NASA

New test techniques and analytical procedures for understanding the behavior of advanced propellers

NASA Technical Reports Server (NTRS)

Stefko, G. L.; Bober, L. J.; Neumann, H. E.

1983-01-01

Analytical procedures and experimental techniques were developed to improve the capability to design advanced high speed propellers. Some results from the propeller lifting line and lifting surface aerodynamic analysis codes are compared with propeller force data, probe data and laser velocimeter data. In general, the code comparisons with data indicate good qualitative agreement. A rotating propeller force balance demonstrated good accuracy and reduced test time by 50 percent. Results from three propeller flow visualization techniques are shown which illustrate some of the physical phenomena occurring on these propellers.

Qualification Test Report for 450 Gallon Crashworthy Fuel Tank for U.S. Air Force H-53 Helicopter. Volume 6

DTIC Science & Technology

1982-04-02

General S130 Eclipse computer. 2.2.3 Photographic Coverage Each crash test was recorded on 16 mm color film by four W cameras. The event was filmed at...rotate further nose-up until impact. Unfortunately, all cameras had either run out of film or had been turned off prior to impact so that there is no...record of impact angle or crash events. From visual observations at the time, the impact angle seemed to be nearly 90* nose-up. What film exists

Visual outcome and rotational stability of open loop toric intraocular lens implantation in Indian eyes.

PubMed

Venkataraman, Arvind

2013-11-01

To assess the visual outcome and rotational stability of single-piece open loop toric Intra Ocular Lens (IOL) in a clinical setting. In a prospective study, 122 eyes of 77 patients were followed up for a period of 12 months after cataract surgery with toric open loop IOL implantation. The pre-operative markings for the position of incision and IOL placement were done under slit lamp by anterior stromal puncture. The visual acuity, refraction, and IOL position were assessed at day 1, 1 week, 1 month, 3 months, 6 months, and 12 months after surgery. The mean age of the cohort was 56 yrs (S.D. 13.88; range 16 to 87 years). The mean pre-operative cylinder of corneal astigmatism was 1.37 D. (SD 0.79, range 1.0 to 5.87 D). Mean post-operative refractive cylinder was 0.36 D (SD 0.57, range 0 to 1.50 D) at 12 months. Ninety-seven percent of the eyes were within 1 D of residual astigmatism. Ninety-four percent of patients had uncorrected visual acuity of 20/30 or better. Four eyes required IOL repositioning due to rotation. At 12 months, 96.7% of the IOLs were within 10 degrees of the target axis. There was no rotation seen after 6 months. Toric IOLs are very effective and consistent in correcting astigmatism during the cataract surgery. IOL rotation happens mostly within a month of surgery, and if significant, requires early repositioning.

Laterality, spatial abilities, and accident proneness.

PubMed

Voyer, Susan D; Voyer, Daniel

2015-01-01

Although handedness as a measure of cerebral specialization has been linked to accident proneness, more direct measures of laterality are rarely considered. The present study aimed to fill that gap in the existing research. In addition, individual difference factors in accident proneness were further examined with the inclusion of mental rotation and navigation abilities measures. One hundred and forty participants were asked to complete the Mental Rotations Test, the Santa Barbara Sense of Direction scale, the Greyscales task, the Fused Dichotic Word Test, the Waterloo Handedness Questionnaire, and a grip strength task before answering questions related to number of accidents in five areas. Results indicated that handedness scores, absolute visual laterality score, absolute response time on the auditory laterality index, and navigation ability were significant predictors of the total number of accidents. Results are discussed with respect to cerebral hemispheric specialization and risk-taking attitudes and behavior.

Autogenic-feedback training: A preventive method for space adaptation syndrome

NASA Technical Reports Server (NTRS)

Cowings, Patricia S.; Sharp, Joseph C.; Toscano, William B.; Kamiya, Joe; Miller, Neal E.

1987-01-01

The progress made to date on the reduction of data for Spacelab 3 Shuttle experiment, No. 3AFT23 is reported. Four astronauts participated as subjects in this experiment. Crewmen A and B served as treatment subjects (i.e., received preflight training for control of their own motion sickness symptoms) and Crewmen C and D served as control (i.e., did not receive training). A preliminary evaluation of Autogenic Feedback Training (AFT) was made from visual inspections of graphs that were generated from the preflight and inflight and inflight physiological data which included: (1) Baseline rotating chair tests for all crewmen; (2) Posttraining rotating chair tests of treatment groups subjects; (3) Preflight data from Joint Integrated Simulations for all crewmen; and (4) Flight data for all crewmen during mission days 0 through 4, and mission day 6 for treatment subjects only. A summary of the findings suggested by these data is outlined.

The dynamics of plus end polarization and microtubule assembly during Xenopus cortical rotation

PubMed Central

Olson, David J.; Oh, Denise

2015-01-01

The self-organization of dorsally-directed microtubules during cortical rotation in the Xenopus egg is essential for dorsal axis formation. The mechanisms controlling this process have been problematic to analyze, owing to difficulties in visualizing microtubules in living egg. Also, the order of events occurring at the onset of cortical rotation have not been satisfactorily visualized in vivo and have been inferred from staged fixed samples. To address these issues, we have characterized the dynamics of total microtubule and plus end behavior continuously throughout cortical rotation, as well as in oocytes and unfertilized eggs. Here, we show that the nascent microtubule network forms in the cortex but associates with the deep cytoplasm at the start of rotation. Importantly, plus ends remain cortical and become increasingly more numerous and active prior to rotation, with dorsal polarization occurring rapidly after the onset of rotation. Additionally, we show that vegetally localized Trim36 is required to attenuate dynamic plus end growth, suggesting that vegetal factors are needed to locally coordinate growth in the cortex. PMID:25753733

Evaluation of rotation and visual outcomes after implantation of monofocal and multifocal toric intraocular lenses.

PubMed

Garzón, Nuria; Poyales, Francisco; de Zárate, Begoña Ortíz; Ruiz-García, Jose Luis; Quiroga, Juan Antonio

2015-02-01

To evaluate rotational stability and its influence on postoperative visual acuity of different monofocal and multifocal toric intraocular lenses (IOLs). A prospective interventional study was designed. Ninety-one patients with a mean age of 71.65 ± 11.82 years were implanted with toric IOLs after phacoemulsification. Three monofocal toric IOLs (the Lentis LT [Oculentis, Berlin, Germany], enVista [Bausch & Lomb, Rochester, NY], and AcrySof IQ [Alcon Laboratories, Inc., Fort Worth, TX]) and one multifocal toric IOL (AcrySof IQ ReSTOR; Alcon Laboratories, Inc.) were implanted. Preoperative and postoperative images were taken to calculate the misalignment due to the marking method. To evaluate rotation in the different follow-up visits, another photograph was taken 1 hour and 1, 7 and 30 days postoperatively. Refraction, uncorrected distance visual acuity (UDVA), and corrected distance visual acuity were measured 30 days postoperatively. Postoperative UDVA was 0.1 logMAR or better in 64.6% of eyes implanted with monofocal IOLs and 46.4% of eyes implanted with multifocal IOLs. The enVista toric IOL showed the best UDVA compared to the other monofocal IOLs, with 81% of eyes with 0.1 logMAR or better. The mean misalignment in the total group studied was 0.07° ± 0.60°; 69.6% of monofocal IOLs and 67.9% of multifocal IOLs showed less than 5° of rotation. A correlation was found between postoperative UDVA and rotation in the monofocal and multifocal IOLs implanted (r = 0.439 [P < .011] and = 0.787 [P = .001], respectively). At 1 month postoperatively, UDVA was slightly more affected by IOL rotation in multifocal than monofocal toric IOLs. The marking method was also effective. Copyright 2015, SLACK Incorporated.

Does Increased Body Mass Index Influence Outcomes After Rotator Cuff Repair?

PubMed

Kessler, Katie E; Robbins, Christopher B; Bedi, Asheesh; Carpenter, James E; Gagnier, Joel J; Miller, Bruce S

2018-03-01

To investigate the influence of pre-existing obesity (body mass index [BMI] ≥ 30) on outcomes after rotator cuff repair surgery. We collected data on adult patients who underwent surgical repair for symptomatic full-thickness rotator cuff tears confirmed by imaging between 2012 and 2015. The required follow-up was 3 years. At baseline and 6, 12, 24, and 36 months, the American Shoulder and Elbow Surgeons score, Western Ontario Rotator Cuff index, and visual analog scale pain scores were collected. Complications were assessed by a chart review. Obesity was defined as BMI ≥ 30. Chi-square analysis and Student's t-test examined differences between categorical and continuous variables at baseline. Generalized estimating equations examined the effects of fixed factors on outcome variables longitudinally from baseline to 36 months. Thirty-nine percent of 213 subjects were obese (mean BMI = 29.2; range, 16-48; standard deviation, 5.8). There were no statistically significant differences between obese and nonobese subjects in other baseline characteristics. When controlling for covariates, obese subjects reported no differences in Western Ontario Rotator Cuff, American Shoulder and Elbow Surgeons, or visual analog scale pain scores when compared with nonobese subjects at baseline and over 3 years from surgery. Although obese patients were more likely to have inpatient surgery, there was no difference in the incidence of postoperative complications. Contrary to our hypothesis, obese participants who underwent rotator cuff repair reported no difference in functional outcome or pain scores compared with nonobese participants over 3 years. In addition, obesity was not associated with postoperative complications in this study. However, as we hypothesized, obese participants were more likely than nonobese participants to have repair in the inpatient setting. Level III, retrospective comparative study. Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Is digital photography an accurate and precise method for measuring range of motion of the hip and knee?

PubMed

Russo, Russell R; Burn, Matthew B; Ismaily, Sabir K; Gerrie, Brayden J; Han, Shuyang; Alexander, Jerry; Lenherr, Christopher; Noble, Philip C; Harris, Joshua D; McCulloch, Patrick C

2017-09-07

Accurate measurements of knee and hip motion are required for management of musculoskeletal pathology. The purpose of this investigation was to compare three techniques for measuring motion at the hip and knee. The authors hypothesized that digital photography would be equivalent in accuracy and show higher precision compared to the other two techniques. Using infrared motion capture analysis as the reference standard, hip flexion/abduction/internal rotation/external rotation and knee flexion/extension were measured using visual estimation, goniometry, and photography on 10 fresh frozen cadavers. These measurements were performed by three physical therapists and three orthopaedic surgeons. Accuracy was defined by the difference from the reference standard, while precision was defined by the proportion of measurements within either 5° or 10°. Analysis of variance (ANOVA), t-tests, and chi-squared tests were used. Although two statistically significant differences were found in measurement accuracy between the three techniques, neither of these differences met clinical significance (difference of 1.4° for hip abduction and 1.7° for the knee extension). Precision of measurements was significantly higher for digital photography than: (i) visual estimation for hip abduction and knee extension, and (ii) goniometry for knee extension only. There was no clinically significant difference in measurement accuracy between the three techniques for hip and knee motion. Digital photography only showed higher precision for two joint motions (hip abduction and knee extension). Overall digital photography shows equivalent accuracy and near-equivalent precision to visual estimation and goniometry.

Normalization methods in time series of platelet function assays

PubMed Central

Van Poucke, Sven; Zhang, Zhongheng; Roest, Mark; Vukicevic, Milan; Beran, Maud; Lauwereins, Bart; Zheng, Ming-Hua; Henskens, Yvonne; Lancé, Marcus; Marcus, Abraham

2016-01-01

Abstract Platelet function can be quantitatively assessed by specific assays such as light-transmission aggregometry, multiple-electrode aggregometry measuring the response to adenosine diphosphate (ADP), arachidonic acid, collagen, and thrombin-receptor activating peptide and viscoelastic tests such as rotational thromboelastometry (ROTEM). The task of extracting meaningful statistical and clinical information from high-dimensional data spaces in temporal multivariate clinical data represented in multivariate time series is complex. Building insightful visualizations for multivariate time series demands adequate usage of normalization techniques. In this article, various methods for data normalization (z-transformation, range transformation, proportion transformation, and interquartile range) are presented and visualized discussing the most suited approach for platelet function data series. Normalization was calculated per assay (test) for all time points and per time point for all tests. Interquartile range, range transformation, and z-transformation demonstrated the correlation as calculated by the Spearman correlation test, when normalized per assay (test) for all time points. When normalizing per time point for all tests, no correlation could be abstracted from the charts as was the case when using all data as 1 dataset for normalization. PMID:27428217

Rotationally asymmetric multifocal IOL implantation with and without capsular tension ring: refractive and visual outcomes and intraocular optical performance.

PubMed

Alió, Jorge L; Plaza-Puche, Ana B; Piñero, David P

2012-04-01

To ascertain whether the refractive, visual, and intraocular optical quality outcomes of a rotationally asymmetric multifocal intraocular lens (IOL) are enhanced by the use of a capsular tension ring. Ninety consecutive eyes from 53 patients (age range: 36 to 82 years) were divided into two groups: the no ring group comprised 43 eyes implanted with the multifocal rotationally asymmetric Lentis Mplus LS-312 (Oculentis GmbH) without a capsular tension ring; and the ring group comprised 47 eyes with the same IOL with a capsular tension ring. Distance and near visual acuity and refractive outcomes were evaluated pre- and postoperatively. Contrast sensitivity, intraocular aberrations, and defocus curve were evaluated postoperatively. Significant postoperative differences between groups were found in sphere, spherical equivalent refraction, and near addition (P<.02). Regarding defocus curve, significantly better visual acuity was present in eyes with the capsular tension ring for intermediate vision conditions (P<.05). Intraocular aberrometry did not differ significantly between groups (P<.09). Refractive predictability and intermediate visual outcomes with the Lentis Mplus LS-312 IOL improved significantly when implanted in combination with a capsular tension ring. Copyright 2012, SLACK Incorporated.

You Should Be the Specialist! Weak Mental Rotation Performance in Aviation Security Screeners - Reduced Performance Level in Aviation Security with No Gender Effect.

PubMed

Krüger, Jenny K; Suchan, Boris

2016-01-01

Aviation security screeners analyze a large number of X-ray images per day and seem to be experts in mentally rotating diverse kinds of visual objects. A robust gender-effect that men outperform women in the Vandenberg & Kuse mental rotation task has been well documented over the last years. In addition it has been shown that training can positively influence the overall task-performance. Considering this, the aim of the present study was to investigate whether security screeners show better performance in the Mental Rotation Test (MRT) independently of gender. Forty-seven security screeners of both sexes from two German airports were examined with a computer based MRT. Their performance was compared to a large sample of control subjects. The well-known gender-effect favoring men on mental rotation was significant within the control group. However, the security screeners did not show any sex differences suggesting an effect of training and professional performance. Surprisingly this specialized group showed a lower level of overall MRT performance than the control participants. Possible aviation related influences such as secondary effects of work-shift or expertise which can cumulatively cause this result are discussed.

Can CT-based patient-matched instrumentation achieve consistent rotational alignment in knee arthroplasty?

PubMed

Tibesku, C O; Innocenti, B; Wong, P; Salehi, A; Labey, L

2012-02-01

Long-term success of contemporary total knee replacements relies to a large extent on proper implant alignment. This study was undertaken to test whether specimen-matched cutting blocks based on computed axial tomography (CT) scans could provide accurate rotational alignment of the femoral component. CT scans of five fresh frozen full leg cadaver specimens, equipped with infrared reflective markers, were used to produce a specimen-matched femoral cutting block. Using those blocks, the bone cuts were made to implant a bi-compartmental femoral component. Rotational alignment of the components in the horizontal plane was determined using an optical measurement system and compared with all relevant rotational reference axes identified on the CT scans. Average rotational alignment for the bi-compartmental component in the horizontal plane was 1.9° (range 0°-6.3°; standard deviation 2.6°). One specimen that showed the highest deviation from the planned alignment also featured a completely degraded medial articular surface. The CT-based specimen-matched cutting blocks achieved good rotational alignment accuracy except for one specimen with badly damaged cartilage. In such cases, imaging techniques that visualize the cartilage layer might be more suitable to design cutting blocks, as they will provide a better fit and increased surface support.

Neuronal adaptation to simulated and optically-induced astigmatic defocus.

PubMed

Ohlendorf, Arne; Tabernero, Juan; Schaeffel, Frank

2011-03-25

It is well established that spatial adaptation can improve visual acuity over time in the presence of spherical defocus. It is less well known how far adaptation to astigmatic defocus can enhance visual acuity. We adapted subjects to "simulated" and optically-induced "real" astigmatic defocus, and studied how much they adapt and how selective adaptation was for the axis of astigmatism. Ten subjects with a mean age of 26.7±2.4years (range 23-30) were enrolled in the study, three of them myopic (average spherical equivalent (SE)±SD: -3.08±1.42D) and seven emmetropic (average SE±SD: -0.11±0.18D). All had a corrected minimum visual acuity (VA) of logVA 0.0. For adaptation, subjects watched a movie at 4m distance for 10min that was convolved frame-by-frame with an astigmatic point spread function, equivalent to +3D defocus, or they watched an unfiltered movie but with spectacle frames with a 0/+3D astigmatic trial lenses. Subsequently, visual acuity was determined at the same distance, using high contrast letter acuity charts. Four experiments were performed. In experiment (1), simulated astigmatic defocus was presented both for adaptation and testing, in experiment (2) optically-induced astigmatic defocus was presented both for adaptation and testing of visual acuity. In all these cases, the +3D power meridian was at 0°. In experiments (3) and (4), the +3D power meridian was at 0° during adaptation but rotated to 90° during testing. Astigmatic defocus was simulated in experiment (3) but optically-induced in experiment (4). Experiments 1 and 2: adaptation to either simulated or real astigmatic defocus increased visual acuity in both test paradigms, simulated (change in VA 0.086±0.069 log units; p<0.01) and lens-induced astigmatic defocus (change in VA 0.068±0.031 log units; p<0.001). Experiments 3 and 4: when the axis was rotated, the improvement in visual acuity failed to reach significance, both for simulated (change in VA 0.042±0.079 log units; p=0.13) and lens-induced astigmatic defocus (change in VA 0.038±0.086 log units; p=0.19). Adaptation to astigmatic defocus occurs for both simulated and real defocus, and the effects of adaptation seem to be selective for the axis of astigmatism. These observations suggest that adaptation involves a re-adjustment of the spatial filters selectively for astigmatic meridians, although the underlying mechanism must be more complicated than just changes in shapes of the receptive fields of retinal or cortical neurons. Copyright © 2011 Elsevier Ltd. All rights reserved.

Intracontinental movements in Western Gondwanaland: a palaeomagnetic test

NASA Astrophysics Data System (ADS)

Rapalini, A. E.; Abdeldayem, A. L.; Tarling, D. H.

1993-04-01

Early Cretaceous intracontinental movements within Africa and/or South America, to account for misfit problem in the pre-drift reconstruction of Western Gondwana, have been tested using palaeomagnetic poles from both continents. Each continent has been considered as comprising separate subplates according to the boundaries proposed by Pindell and Dewey (1982) and Curie (1983): i.e., northern Africa ( NAF), southern Africa ( SAF), northern South America (nsa) and southern South America ( SSA). Visual and statistical distribution of Late Permian to Jurassic poles from the African subplates indicate two distinct groups before rotating SAF relative to NAF, while after the rotation they become indistinguishable. The distribution and sparsity of data from South America limit the study in this continent as the data are statistically indistinguishable before and after rotation of SSA with respect to NSA. When the test is extended to the reconstruction of Western Gondwana, the tightest grouping of the poles occurs when an intracontinental movement is assumed within Africa. This suggests that the misfit between the two continents is probably due to intracontinental deformation within Africa and not in South America. If confirmed, this may have profound implications in the kinematics of the processes related to the opening of the South and Central Atlantic Oceans and also the origin of the West African Rift System.

What Is Being Done to Control Motion Sickness?

NASA Technical Reports Server (NTRS)

Hall, Y. D.

1985-01-01

AFT (Autogenic Feedback Training) involves practicing a series of mental exercises to speed up or slow down the control of autonomic activity. This produces a reduced tendency for autonomic activity levels to diverge from baseline (at rest) under stressful motion-sickness-inducing conditions. Subjects conditions. Subjects engaged in applying AFT exercises are required to closely monitor their own bodily sensations during motion-sickness-eliciting tests. These tests include the Coriolis Sickness Susceptibility Index (CSSI), which consists of sitting a subject into a rotating chair that moves at various speeds while a visual background turns at differing speeds and directions, and the Vertical Acceleration Rotation Device (VARD) test, which involves the placing of a subject in a drum that moves in an upward and downward motion until he or she is sick, while simultaneously monitoring the subject's vital signs. These tests provide investigators with evidence of slight changes in autonomic activities such as increases in heart rate, skin temperature, and sweat. All of these symptoms occur in subjects that experience bodily weakness or discomfort with the onset of motion sickness.

The contribution of visual and vestibular information to spatial orientation by 6- to 14-month-old infants and adults.

PubMed

Bremner, J Gavin; Hatton, Fran; Foster, Kirsty A; Mason, Uschi

2011-09-01

Although there is much research on infants' ability to orient in space, little is known regarding the information they use to do so. This research uses a rotating room to evaluate the relative contribution of visual and vestibular information to location of a target following bodily rotation. Adults responded precisely on the basis of visual flow information. Seven-month-olds responded mostly on the basis of visual flow, whereas 9-month-olds responded mostly on the basis of vestibular information, and 12-month-olds responded mostly on the basis of visual information. Unlike adults, infants of all ages showed partial influence by both modalities. Additionally, 7-month-olds were capable of using vestibular information when there was no visual information for movement or stability, and 9-month-olds still relied on vestibular information when visual information was enhanced. These results are discussed in the context of neuroscientific evidence regarding visual-vestibular interaction, and in relation to possible changes in reliance on visual and vestibular information following acquisition of locomotion. © 2011 Blackwell Publishing Ltd.

Production and perception rules underlying visual patterns: effects of symmetry and hierarchy.

PubMed

Westphal-Fitch, Gesche; Huber, Ludwig; Gómez, Juan Carlos; Fitch, W Tecumseh

2012-07-19

Formal language theory has been extended to two-dimensional patterns, but little is known about two-dimensional pattern perception. We first examined spontaneous two-dimensional visual pattern production by humans, gathered using a novel touch screen approach. Both spontaneous creative production and subsequent aesthetic ratings show that humans prefer ordered, symmetrical patterns over random patterns. We then further explored pattern-parsing abilities in different human groups, and compared them with pigeons. We generated visual plane patterns based on rules varying in complexity. All human groups tested, including children and individuals diagnosed with autism spectrum disorder (ASD), were able to detect violations of all production rules tested. Our ASD participants detected pattern violations with the same speed and accuracy as matched controls. Children's ability to detect violations of a relatively complex rotational rule correlated with age, whereas their ability to detect violations of a simple translational rule did not. By contrast, even with extensive training, pigeons were unable to detect orientation-based structural violations, suggesting that, unlike humans, they did not learn the underlying structural rules. Visual two-dimensional patterns offer a promising new formally-grounded way to investigate pattern production and perception in general, widely applicable across species and age groups.

Production and perception rules underlying visual patterns: effects of symmetry and hierarchy

PubMed Central

Westphal-Fitch, Gesche; Huber, Ludwig; Gómez, Juan Carlos; Fitch, W. Tecumseh

2012-01-01

Formal language theory has been extended to two-dimensional patterns, but little is known about two-dimensional pattern perception. We first examined spontaneous two-dimensional visual pattern production by humans, gathered using a novel touch screen approach. Both spontaneous creative production and subsequent aesthetic ratings show that humans prefer ordered, symmetrical patterns over random patterns. We then further explored pattern-parsing abilities in different human groups, and compared them with pigeons. We generated visual plane patterns based on rules varying in complexity. All human groups tested, including children and individuals diagnosed with autism spectrum disorder (ASD), were able to detect violations of all production rules tested. Our ASD participants detected pattern violations with the same speed and accuracy as matched controls. Children's ability to detect violations of a relatively complex rotational rule correlated with age, whereas their ability to detect violations of a simple translational rule did not. By contrast, even with extensive training, pigeons were unable to detect orientation-based structural violations, suggesting that, unlike humans, they did not learn the underlying structural rules. Visual two-dimensional patterns offer a promising new formally-grounded way to investigate pattern production and perception in general, widely applicable across species and age groups. PMID:22688636

SDSS-IV MaNGA: the different quenching histories of fast and slow rotators

NASA Astrophysics Data System (ADS)

Smethurst, R. J.; Masters, K. L.; Lintott, C. J.; Weijmans, A.; Merrifield, M.; Penny, S. J.; Aragón-Salamanca, A.; Brownstein, J.; Bundy, K.; Drory, N.; Law, D. R.; Nichol, R. C.

2018-01-01

Do the theorized different formation mechanisms of fast and slow rotators produce an observable difference in their star formation histories? To study this, we identify quenching slow rotators in the MaNGA sample by selecting those that lie below the star-forming sequence and identify a sample of quenching fast rotators that were matched in stellar mass. This results in a total sample of 194 kinematically classified galaxies, which is agnostic to visual morphology. We use u - r and NUV - u colours from the Sloan Digital Sky Survey and GALEX and an existing inference package, STARPY, to conduct a first look at the onset time and exponentially declining rate of quenching of these galaxies. An Anderson-Darling test on the distribution of the inferred quenching rates across the two kinematic populations reveals they are statistically distinguishable (3.2σ). We find that fast rotators quench at a much wider range of rates than slow rotators, consistent with a wide variety of physical processes such as secular evolution, minor mergers, gas accretion and environmentally driven mechanisms. Quenching is more likely to occur at rapid rates (τ ≲ 1 Gyr) for slow rotators, in agreement with theories suggesting slow rotators are formed in dynamically fast processes, such as major mergers. Interestingly, we also find that a subset of the fast rotators quench at these same rapid rates as the bulk of the slow rotator sample. We therefore discuss how the total gas mass of a merger, rather than the merger mass ratio, may decide a galaxy's ultimate kinematic fate.

Development of a hemispherical rotational modulation collimator system for imaging spatial distribution of radiation sources

NASA Astrophysics Data System (ADS)

Na, M.; Lee, S.; Kim, G.; Kim, H. S.; Rho, J.; Ok, J. G.

2017-12-01

Detecting and mapping the spatial distribution of radioactive materials is of great importance for environmental and security issues. We design and present a novel hemispherical rotational modulation collimator (H-RMC) system which can visualize the location of the radiation source by collecting signals from incident rays that go through collimator masks. The H-RMC system comprises a servo motor-controlled rotating module and a hollow heavy-metallic hemisphere with slits/slats equally spaced with the same angle subtended from the main axis. In addition, we also designed an auxiliary instrument to test the imaging performance of the H-RMC system, comprising a high-precision x- and y-axis staging station on which one can mount radiation sources of various shapes. We fabricated the H-RMC system which can be operated in a fully-automated fashion through the computer-based controller, and verify the accuracy and reproducibility of the system by measuring the rotational and linear positions with respect to the programmed values. Our H-RMC system may provide a pivotal tool for spatial radiation imaging with high reliability and accuracy.

Rotation elastogram: a novel method to visualize local rigid body rotation under quasi-static compression

NASA Astrophysics Data System (ADS)

Sowmiya, C.; Kothawala, Ali Arshad; Thittai, Arun K.

2016-04-01

During manual palpation of breast masses, the perception of its stiffness and slipperiness are the two commonly used information by the physician. In order to reliably and quantitatively obtain this information several non-invasive elastography techniques have been developed that seek to provide an image of the underlying mechanical properties, mostly stiffness-related. Very few approaches have visualized the "slip" at the lesion-background boundary that only occurs for a loosely-bonded benign lesion. It has been shown that axial-shear strain distribution provides information about underlying slip. One such feature, referred to as "fill-in" was interpreted as a surrogate of the rotation undergone by an asymmetrically-oriented-loosely bonded-benign-lesion under quasi-static compression. However, imaging and direct visualization of the rotation itself has not been addressed yet. In order to accomplish this, the quality of lateral displacement estimation needs to be improved. In this simulation study, we utilize spatial compounding approach and assess the feasibility to obtain good quality rotation elastogram. The angular axial and lateral displacement estimates were obtained at different insonification angles from a phantom containing an elliptical inclusion oriented at 45°, subjected to 1% compression from the top. A multilevel 2D-block matching algorithm was used for displacement tracking and 2D-least square compounding of angular axial and lateral displacement estimates was employed. By varying the maximum steering angle and incremental angle, the improvement in the lateral motion tracking accuracy and its effects on the quality of rotational elastogram were evaluated. Results demonstrate significantly-improved rotation elastogram using this technique.

Experience affects the use of ego-motion signals during 3D shape perception.

PubMed

Jain, Anshul; Backus, Benjamin T

2010-12-29

Experience has long-term effects on perceptual appearance (Q. Haijiang, J. A. Saunders, R. W. Stone, & B. T. Backus, 2006). We asked whether experience affects the appearance of structure-from-motion stimuli when the optic flow is caused by observer ego-motion. Optic flow is an ambiguous depth cue: a rotating object and its oppositely rotating, depth-inverted dual generate similar flow. However, the visual system exploits ego-motion signals to prefer the percept of an object that is stationary over one that rotates (M. Wexler, F. Panerai, I. Lamouret, & J. Droulez, 2001). We replicated this finding and asked whether this preference for stationarity, the "stationarity prior," is modulated by experience. During training, two groups of observers were exposed to objects with identical flow, but that were either stationary or moving as determined by other cues. The training caused identical test stimuli to be seen preferentially as stationary or moving by the two groups, respectively. We then asked whether different priors can exist independently at different locations in the visual field. Observers were trained to see objects either as stationary or as moving at two different locations. Observers' stationarity bias at the two respective locations was modulated in the directions consistent with training. Thus, the utilization of extraretinal ego-motion signals for disambiguating optic flow signals can be updated as the result of experience, consistent with the updating of a Bayesian prior for stationarity.

Mathematical visualization process of junior high school students in solving a contextual problem based on cognitive style

NASA Astrophysics Data System (ADS)

Utomo, Edy Setiyo; Juniati, Dwi; Siswono, Tatag Yuli Eko

2017-08-01

The aim of this research was to describe the mathematical visualization process of Junior High School students in solving contextual problems based on cognitive style. Mathematical visualization process in this research was seen from aspects of image generation, image inspection, image scanning, and image transformation. The research subject was the students in the eighth grade based on GEFT test (Group Embedded Figures Test) adopted from Within to determining the category of cognitive style owned by the students namely field independent or field dependent and communicative. The data collection was through visualization test in contextual problem and interview. The validity was seen through time triangulation. The data analysis referred to the aspect of mathematical visualization through steps of categorization, reduction, discussion, and conclusion. The results showed that field-independent and field-dependent subjects were difference in responding to contextual problems. The field-independent subject presented in the form of 2D and 3D, while the field-dependent subject presented in the form of 3D. Both of the subjects had different perception to see the swimming pool. The field-independent subject saw from the top, while the field-dependent subject from the side. The field-independent subject chose to use partition-object strategy, while the field-dependent subject chose to use general-object strategy. Both the subjects did transformation in an object rotation to get the solution. This research is reference to mathematical curriculum developers of Junior High School in Indonesia. Besides, teacher could develop the students' mathematical visualization by using technology media or software, such as geogebra, portable cabri in learning.

Effects of kinesthetic versus visual imagery practice on two technical dance movements: a pilot study.

PubMed

Girón, Elizabeth Coker; McIsaac, Tara; Nilsen, Dawn

2012-03-01

Motor imagery is a type of mental practice that involves imagining the body performing a movement in the absence of motor output. Dance training traditionally incorporates mental practice techniques, but quantitative effects of motor imagery on the performance of dance movements are largely unknown. This pilot study compared the effects of two different imagery modalities, external visual imagery and kinesthetic imagery, on pelvis and hip kinematics during two technical dance movements, plié and sauté. Each of three female dance students (mean age = 19.7 years, mean years of training = 10.7) was assigned to use a type of imagery practice: visual imagery, kinesthetic imagery, or no imagery. Effects of motor imagery on peak external hip rotation varied by both modality and task. Kinesthetic imagery increased peak external hip rotation for pliés, while visual imagery increased peak external hip rotation for sautés. Findings suggest that the success of motor imagery in improving performance may be task-specific. Dancers may benefit from matching imagery modality to technical tasks in order to improve alignment and thereby avoid chronic injury.

Sensory substitution information informs locomotor adjustments when walking through apertures.

PubMed

Kolarik, Andrew J; Timmis, Matthew A; Cirstea, Silvia; Pardhan, Shahina

2014-03-01

The study assessed the ability of the central nervous system (CNS) to use echoic information from sensory substitution devices (SSDs) to rotate the shoulders and safely pass through apertures of different width. Ten visually normal participants performed this task with full vision, or blindfolded using an SSD to obtain information regarding the width of an aperture created by two parallel panels. Two SSDs were tested. Participants passed through apertures of +0, +18, +35 and +70 % of measured body width. Kinematic indices recorded movement time, shoulder rotation, average walking velocity across the trial, peak walking velocities before crossing, after crossing and throughout a whole trial. Analyses showed participants used SSD information to regulate shoulder rotation, with greater rotation associated with narrower apertures. Rotations made using an SSD were greater compared to vision, movement times were longer, average walking velocity lower and peak velocities before crossing, after crossing and throughout the whole trial were smaller, suggesting greater caution. Collisions sometimes occurred using an SSD but not using vision, indicating that substituted information did not always result in accurate shoulder rotation judgements. No differences were found between the two SSDs. The data suggest that spatial information, provided by sensory substitution, allows the relative position of aperture panels to be internally represented, enabling the CNS to modify shoulder rotation according to aperture width. Increased buffer space indicated by greater rotations (up to approximately 35 % for apertures of +18 % of body width) suggests that spatial representations are not as accurate as offered by full vision.

Multiple-stage ambiguity in motion perception reveals global computation of local motion directions.

PubMed

Rider, Andrew T; Nishida, Shin'ya; Johnston, Alan

2016-12-01

The motion of a 1D image feature, such as a line, seen through a small aperture, or the small receptive field of a neural motion sensor, is underconstrained, and it is not possible to derive the true motion direction from a single local measurement. This is referred to as the aperture problem. How the visual system solves the aperture problem is a fundamental question in visual motion research. In the estimation of motion vectors through integration of ambiguous local motion measurements at different positions, conventional theories assume that the object motion is a rigid translation, with motion signals sharing a common motion vector within the spatial region over which the aperture problem is solved. However, this strategy fails for global rotation. Here we show that the human visual system can estimate global rotation directly through spatial pooling of locally ambiguous measurements, without an intervening step that computes local motion vectors. We designed a novel ambiguous global flow stimulus, which is globally as well as locally ambiguous. The global ambiguity implies that the stimulus is simultaneously consistent with both a global rigid translation and an infinite number of global rigid rotations. By the standard view, the motion should always be seen as a global translation, but it appears to shift from translation to rotation as observers shift fixation. This finding indicates that the visual system can estimate local vectors using a global rotation constraint, and suggests that local motion ambiguity may not be resolved until consistencies with multiple global motion patterns are assessed.

Visual outcome and rotational stability of open loop toric intraocular lens implantation in Indian eyes

PubMed Central

Venkataraman, Arvind; Kalpana

2013-01-01

Purpose: To assess the visual outcome and rotational stability of single-piece open loop toric Intra Ocular Lens (IOL) in a clinical setting. Materials and Methods: In a prospective study, 122 eyes of 77 patients were followed up for a period of 12 months after cataract surgery with toric open loop IOL implantation. The pre-operative markings for the position of incision and IOL placement were done under slit lamp by anterior stromal puncture. The visual acuity, refraction, and IOL position were assessed at day 1, 1 week, 1 month, 3 months, 6 months, and 12 months after surgery. Results: The mean age of the cohort was 56 yrs (S.D. 13.88; range 16 to 87 years). The mean pre-operative cylinder of corneal astigmatism was 1.37 D. (SD 0.79, range 1.0 to 5.87 D). Mean post-operative refractive cylinder was 0.36 D (SD 0.57, range 0 to 1.50 D) at 12 months. Ninety-seven percent of the eyes were within 1 D of residual astigmatism. Ninety-four percent of patients had uncorrected visual acuity of 20/30 or better. Four eyes required IOL repositioning due to rotation. At 12 months, 96.7% of the IOLs were within 10 degrees of the target axis. There was no rotation seen after 6 months. Conclusion: Toric IOLs are very effective and consistent in correcting astigmatism during the cataract surgery. IOL rotation happens mostly within a month of surgery, and if significant, requires early repositioning. PMID:24343593

Forward rotor vortex effects on counter rotating propeller noise

NASA Technical Reports Server (NTRS)

Laur, Michele; Squires, Becky; Nagel, Robert T.

1992-01-01

Three configurations of a model counter rotating propeller manipulate the blade tip flow by: placing the CRP at angle of attack, installing shrouds, and turning the upstream blades to provide forward sweep. Flow visualization and flow measurements with thermal anemometry show no evidence of a tip vortex; however, a leading edge vortex was detected on aft swept blades. The modifications served to alter the strength and/or path of the leading edge vortex. The vortical flow is eliminated by forward sweep on the upstream propeller blades. Far field acoustic data from each test indicate only small influences on the level and directivity of the BPFs. The interaction tone at the sum of the two BPF's was significantly altered in a consistent manner. As the vortex system varied, the interaction tone was affected: far field noise levels in the forward quandrant increased and the characteristic noise minimum near the plane of rotation became less pronounced and in some cases were eliminated. If the forward propeller leading edge vortex system does not impact the rear propeller in the standard manner, a net increase in the primary interaction tone occurs for the model tested. If the leading edge vortex is removed, the interaction tone increases.

Head Rotation Movement Times.

PubMed

Hoffmann, Errol R; Chan, Alan H S; Heung, P T

2017-09-01

The aim of this study was to measure head rotation movement times in a Fitts' paradigm and to investigate the transition region from ballistic movements to visually controlled movements as the task index of difficulty (ID) increases. For head rotation, there are gaps in the knowledge of the effects of movement amplitude and task difficulty around the critical transition region from ballistic movements to visually controlled movements. Under the conditions of 11 ID values (from 1.0 to 6.0) and five movement amplitudes (20° to 60°), participants performed a head rotation task, and movement times were measured. Both the movement amplitude and task difficulty have effects on movement times at low IDs, but movement times are dependent only on ID at higher ID values. Movement times of participants are higher than for arm/hand movements, for both ballistic and visually controlled movements. The information-processing rate of head rotational movements, at high ID values, is about half that of arm movements. As an input mode, head rotations are not as efficient as the arm system either in ability to use rapid ballistic movements or in the rate at which information may be processed. The data of this study add to those in the review of Hoffmann for the critical IDs of different body motions. The data also allow design for the best arrangement of display that is under the design constraints of limited display area and difficulty of head-controlled movements in a data-inputting task.

Dynamic modulation of ocular orientation during visually guided saccades and smooth-pursuit eye movements

NASA Technical Reports Server (NTRS)

Hess, Bernhard J M.; Angelaki, Dora E.

2003-01-01

Rotational disturbances of the head about an off-vertical yaw axis induce a complex vestibuloocular reflex pattern that reflects the brain's estimate of head angular velocity as well as its estimate of instantaneous head orientation (at a reduced scale) in space coordinates. We show that semicircular canal and otolith inputs modulate torsional and, to a certain extent, also vertical ocular orientation of visually guided saccades and smooth-pursuit eye movements in a similar manner as during off-vertical axis rotations in complete darkness. It is suggested that this graviceptive control of eye orientation facilitates rapid visual spatial orientation during motion.

The flow of a thin liquid film on a stationary and rotating disk. I - Experimental analysis and flow visualization

NASA Technical Reports Server (NTRS)

Thomas, S.; Faghri, A.; Hankey, W.

1990-01-01

The mean thickness of a thin liquid film of deionized water with a free surface on a stationary and rotating horizontal disk has been measured with a nonobtrusive capacitance technique. The measurements were taken when the rotational speed was 0-300 RPM and the flow rate was 7.0-15.0 LPM. A flow visualization study of the thin film was also performed to determine the characteristics of the waves on the free surface. When the disk was stationary, a circular hydraulic jump was present on the disk. Surface waves were found in the supercritical and subcritical regions at all flow rates studied. When the rotational speed of the disk is low, a standing wave at the edge of the disk was present. As the rotational speed increased, the surface waves changed from the wavy-laminar region to a region in which the waves ran nearly radially across the disk on top of a thin substrate of fluid.

Effects of angular acceleration on man - Choice reaction time using visual and rotary motion information

NASA Technical Reports Server (NTRS)

Clark, B.; Stewart, J. D.

1974-01-01

This experiment was concerned with the effects of rotary acceleration on choice reaction time (RTc) to the motion of a luminous line on a cathode-ray tube. Specifically, it compared the (RTc) to rotary acceleration alone, visual acceleration alone, and simultaneous, double stimulation by both rotary and visual acceleration. Thirteen airline pilots were rotated about an earth-vertical axis in a precision rotation device while they observed a vertical line. The stimuli were 7 rotary and visual accelerations which were matched for rise time. The pilot responded as quickly as possible by displacing a vertical controller to the right or left. The results showed a decreasing (RTc) with increasing acceleration for all conditions, while the (RTc) to rotary motion alone was substantially longer than for all other conditions. The (RTc) to the double stimulation was significantly longer than that for visual acceleration alone.

Experimental Investigation of Normal Shock Boundary-Layer Interaction with Hybrid Flow Control

NASA Technical Reports Server (NTRS)

Vyas, Manan A.; Hirt, Stefanie M.; Anderson, Bernhard H.

2012-01-01

Hybrid flow control, a combination of micro-ramps and micro-jets, was experimentally investigated in the 15x15 cm Supersonic Wind Tunnel (SWT) at the NASA Glenn Research Center. Full factorial, a design of experiments (DOE) method, was used to develop a test matrix with variables such as inter-ramp spacing, ramp height and chord length, and micro-jet injection flow ratio. A total of 17 configurations were tested with various parameters to meet the DOE criteria. In addition to boundary-layer measurements, oil flow visualization was used to qualitatively understand shock induced flow separation characteristics. The flow visualization showed the normal shock location, size of the separation, path of the downstream moving counter-rotating vortices, and corner flow effects. The results show that hybrid flow control demonstrates promise in reducing the size of shock boundary-layer interactions and resulting flow separation by means of energizing the boundary layer.

Visualization and Measurement of Flow in a Model Rotating-Wall Bioreactor

NASA Astrophysics Data System (ADS)

Brown, Jason B.; Neitzel, G. Paul

1997-11-01

Fluid shear has been observed to have an effect on the in vitro growth of mammalian cells and is expected to play a role in the in vitro development of aggregates of cells into tissue. The interactions between culture media and cell constructs within a circular Couette flow bioreactor with independently rotating cylinders are investigated in model studies using flow visualization. Particle-Image Velocimetry (PIV) is used to quantify the velocity field in a plane perpendicular to the vessel axis which contains a cell construct model. This velocity field is then used to compute the instantaneous shear field. Experiments show the path of the model cell construct is dependent on the rotation rates of the cylinders.

Three-dimensional analysis of scoliosis surgery using stereophotogrammetry

NASA Astrophysics Data System (ADS)

Jang, Stanley B.; Booth, Kellogg S.; Reilly, Chris W.; Sawatzky, Bonita J.; Tredwell, Stephen J.

1994-04-01

A new stereophotogrammetric analysis and 3D visualization allow accurate assessment of the scoliotic spine during instrumentation. Stereophoto pairs taken at each stage of the operation and robust statistical techniques are used to compute 3D transformations of the vertebrae between stages. These determine rotation, translation, goodness of fit, and overall spinal contour. A polygonal model of the spine using commercial 3D modeling package is used to produce an animation sequence of the transformation. The visualization have provided some important observation. Correction of the scoliosis is achieved largely through vertebral translation and coronal plane rotation, contrary to claims that large axial rotations are required. The animations provide valuable qualitative information for surgeons assessing the results of scoliotic correction.

Map display design

NASA Technical Reports Server (NTRS)

Aretz, Anthony J.

1990-01-01

This paper presents a cognitive model of a pilot's navigation task and describes an experiment comparing a visual momentum map display to the traditional track-up and north-up approaches. The data show the advantage to a track-up map is its congruence with the ego-centered forward view; however, the development of survey knowledge is hindered by the inconsistency of the rotating display. The stable alignment of a north-up map aids the acquisition of survey knowledge, but there is a cost associated with the mental rotation of the display to a track-up alignment for ego-centered tasks. The results also show that visual momentum can be used to reduce the mental rotation costs of a north-up display.

Multiple Concurrent Visual-Motor Mappings: Implications for Models of Adaptation

NASA Technical Reports Server (NTRS)

Cunningham, H. A.; Welch, Robert B.

1994-01-01

Previous research on adaptation to visual-motor rearrangement suggests that the central nervous system represents accurately only 1 visual-motor mapping at a time. This idea was examined in 3 experiments where subjects tracked a moving target under repeated alternations between 2 initially interfering mappings (the 'normal' mapping characteristic of computer input devices and a 108' rotation of the normal mapping). Alternation between the 2 mappings led to significant reduction in error under the rotated mapping and significant reduction in the adaptation aftereffect ordinarily caused by switching between mappings. Color as a discriminative cue, interference versus decay in adaptation aftereffect, and intermanual transfer were also examined. The results reveal a capacity for multiple concurrent visual-motor mappings, possibly controlled by a parametric process near the motor output stage of processing.

Effects of translational and rotational motions and display polarity on visual performance.

PubMed

Feng, Wen-Yang; Tseng, Feng-Yi; Chao, Chin-Jung; Lin, Chiuhsiang Joe

2008-10-01

This study investigated effects of both translational and rotational motion and display polarity on a visual identification task. Three different motion types--heave, roll, and pitch--were compared with the static (no motion) condition. The visual task was presented on two display polarities, black-on-white and white-on-black. The experiment was a 4 (motion conditions) x 2 (display polarities) within-subjects design with eight subjects (six men and two women; M age = 25.6 yr., SD = 3.2). The dependent variables used to assess the performance on the visual task were accuracy and reaction time. Motion environments, especially the roll condition, had statistically significant effects on the decrement of accuracy and reaction time. The display polarity was significant only in the static condition.

Outside The Box: What Would a Scientist Do with a Dashboard?

NASA Technical Reports Server (NTRS)

Blakeley, Christopher M.

2013-01-01

Growing plants on the International Space Station has always been a challenge, but it is research that must continue in order to support long duration missions. A rotating plant system is now undergoing tests at Kennedy Space Center to help mitigate the challenges of getting water and nutrients effectively to plant roots. Traditionally, lab test data is gathered and presented via spreadsheets which can be confusing and cumbersome to deal with. Using SAP BusinessObjects Dashboards (formerly Xcelsius), see how NASA utilizes this visualization software to help monitor and present a clear picture of the research results.

Fluctuation in visual acuity during soft toric contact lens wear.

PubMed

Chamberlain, Paul; Morgan, Philip B; Moody, Kurt J; Maldonado-Codina, Carole

2011-04-01

To quantify changes in visual acuity (VA) with soft toric contact lenses as a result of lens movement and/or rotational instability caused by versional eye movements. A novel chart for vision assessment at near (40 cm) for soft toric contact lenses (VANT chart),consisting of a central, color-coded logMAR panel and eight peripheral letter targets set on a white background measuring 60 × 40 cm was constructed. In the developmental phase of the work, 10 subjects (20 eyes) wore 2 toric lenses in random order, and the impact of rapid and delayed eye versions in 8 directions of gaze on VANT acuity was investigated. In phase 2, 35 subjects (68 eyes) wore 4 toric lenses in random order, and a streamlined clinical protocol using the VANT chart was implemented. Standard assessments of toric lens fit and distance VA were also performed. Testing in the first phase showed no difference for change in VA for rapid vs. delayed version movements, (p = 0.17) but acuity reduction was greater for diagonal compared with horizontal/vertical versions (p = 0.06). As such, testing in phase 2 proceeded using rapid, diagonal versions only. In this second phase, there were differences for low-contrast distance VA measures between lens types (p = 0.02) and for both VANT baseline acuity (p = 0.03) and postversion acuity (p = 0.04), but no differences were found between lenses for magnitude of vision loss (p = 0.91), which was about one line. No relationship was established between the magnitude of vision loss and measured rotational stability (p = 0.75). This work has demonstrated that conventional approaches to measuring VA do not fully replicate the "real world" experience of soft toric lens wearers. The VANT chart has shown that VA is reduced immediately after versional eye movements and suggests that more dynamic methods of assessing visual performance should be considered for soft toric contact lens wearers, especially given the apparent inability of lens stability measurements to predict visual performance.

The impact of inverted text on visual word processing: An fMRI study.

PubMed

Sussman, Bethany L; Reddigari, Samir; Newman, Sharlene D

2018-06-01

Visual word recognition has been studied for decades. One question that has received limited attention is how different text presentation orientations disrupt word recognition. By examining how word recognition processes may be disrupted by different text orientations it is hoped that new insights can be gained concerning the process. Here, we examined the impact of rotating and inverting text on the neural network responsible for visual word recognition focusing primarily on a region of the occipto-temporal cortex referred to as the visual word form area (VWFA). A lexical decision task was employed in which words and pseudowords were presented in one of three orientations (upright, rotated or inverted). The results demonstrate that inversion caused the greatest disruption of visual word recognition processes. Both rotated and inverted text elicited increased activation in spatial attention regions within the right parietal cortex. However, inverted text recruited phonological and articulatory processing regions within the left inferior frontal and left inferior parietal cortices. Finally, the VWFA was found to not behave similarly to the fusiform face area in that unusual text orientations resulted in increased activation and not decreased activation. It is hypothesized here that the VWFA activation is modulated by feedback from linguistic processes. Copyright © 2018 Elsevier Inc. All rights reserved.

The Effects of Visual Discriminability and Rotation Angle on 30-Month-Olds’ Search Performance in Spatial Rotation Tasks

PubMed Central

Ebersbach, Mirjam; Nawroth, Christian

2016-01-01

Tracking objects that are hidden and then moved is a crucial ability related to object permanence, which develops across several stages in early childhood. In spatial rotation tasks, children observe a target object that is hidden in one of two or more containers before the containers are rotated around a fixed axis. Usually, 30-month-olds fail to find the hidden object after it was rotated by 180°. We examined whether visual discriminability of the containers improves 30-month-olds’ success in this task and whether children perform better after 90° than after 180° rotations. Two potential hiding containers with same or different colors were placed on a board that was rotated by 90° or 180° in a within-subjects design. Children (N = 29) performed above chance level in all four conditions. Their overall success in finding the object did not improve by differently colored containers. However, different colors prevented children from showing an inhibition bias in 90° rotations, that is, choosing the empty container more often when it was located close to them than when it was farther away: This bias emerged in the same colors condition but not in the different colors condition. Results are discussed in view of particular challenges that might facilitate or deteriorate spatial rotation tasks for young children. PMID:27812346

The Effects of Visual Discriminability and Rotation Angle on 30-Month-Olds' Search Performance in Spatial Rotation Tasks.

PubMed

Ebersbach, Mirjam; Nawroth, Christian

2016-01-01

Tracking objects that are hidden and then moved is a crucial ability related to object permanence, which develops across several stages in early childhood. In spatial rotation tasks, children observe a target object that is hidden in one of two or more containers before the containers are rotated around a fixed axis. Usually, 30-month-olds fail to find the hidden object after it was rotated by 180°. We examined whether visual discriminability of the containers improves 30-month-olds' success in this task and whether children perform better after 90° than after 180° rotations. Two potential hiding containers with same or different colors were placed on a board that was rotated by 90° or 180° in a within-subjects design. Children ( N = 29) performed above chance level in all four conditions. Their overall success in finding the object did not improve by differently colored containers. However, different colors prevented children from showing an inhibition bias in 90° rotations, that is, choosing the empty container more often when it was located close to them than when it was farther away: This bias emerged in the same colors condition but not in the different colors condition. Results are discussed in view of particular challenges that might facilitate or deteriorate spatial rotation tasks for young children.

Processing digital images and calculation of beam emittance (pepper-pot method for the Krion source)

NASA Astrophysics Data System (ADS)

Alexandrov, V. S.; Donets, E. E.; Nyukhalova, E. V.; Kaminsky, A. K.; Sedykh, S. N.; Tuzikov, A. V.; Philippov, A. V.

2016-12-01

Programs for the pre-processing of photographs of beam images on the mask based on Wolfram Mathematica and Origin software are described. Angles of rotation around the axis and in the vertical plane are taken into account in the generation of the file with image coordinates. Results of the emittance calculation by the Pep_emit program written in Visual Basic using the generated file in the test mode are presented.

Effect of viewing distance and location of the axis of head rotation on the monkey's vestibuloocular reflex. I. Eye movement responses.

PubMed

Snyder, L H; King, W M

1992-04-01

1. The vestibuloocular reflex (VOR) stabilizes images on the retina against movements of the head in space. Viewing distance, target eccentricity, and location of the axis of rotation may influence VOR responses because rotation of the head about most axes in space rotates and translates the eyes relative to visual targets. To study the VOR response to combined rotation and translation, monkeys were placed on a rate table and rotated briefly in the dark about a vertical axis that was located in front of or behind the eyes. The monkeys fixated a near or far visual target that was extinguished before the rotation. Eye movements were recorded from both eyes by the use of the search coil technique. 2. Peak eye velocity evoked by the VOR was linearly related to vergence angle for any axis of rotation. The percent change in the VOR with near target viewing relative to far target viewing at a vergence angle of 20 degrees was linearly related to the location of the axis of rotation. Axes located behind the eyes produced positive changes in VOR amplitude, and axes located in front of the eyes produced negative changes in VOR amplitude. An axis of rotation located in the coronal plane containing the centers of rotation of the eyes produced no modification of VOR amplitude. For any axis, the VOR compensated for approximately 90% of the translation of the eye relative to near targets. 3. The initial VOR response was not correct in magnitude but was refined by a series of three temporally delayed corrections of increasing complexity. The earliest VOR-evoked eye movement (10-20 ms after rotation onset) was independent of viewing distance and rotational axis location. In the next 100 ms, eye speed appeared to be sequentially modified three times: within 20 ms by viewing distance; within 30 ms by otolith translation; and within 100 ms by eye translation relative to the visual target. 4. These data suggest a formal model of the VOR consisting of four channels. Channel 1 conveys an unmodified head rotation signal with a pure delay of 10 ms. Channel 2 conveys an angular head velocity signal, modified by viewing distance with a pure delay of 20 ms, but invariant with respect to the location of the axis of rotation. Channel 3 conveys a linear head velocity signal, dependent on the location of the axis of rotation, that is modified by viewing distance with a pure delay of 30 ms.(ABSTRACT TRUNCATED AT 400 WORDS)

Scapular positioning and motor control in children and adults: a laboratory study using clinical measures.

PubMed

Struyf, Filip; Nijs, Jo; Horsten, Stijn; Mottram, Sarah; Truijen, Steven; Meeusen, Romain

2011-04-01

The scapular muscular system is the major determinant of scapular positioning. In addition, strength and muscular endurance develops from childhood through adolescence. It is not known whether differences in scapular positioning and motor control between adults and children may exist. Ninety-two shoulders of 46 adults (mean = 39.4; 18-86 years; SD = 22.5), and 116 shoulders of 59 children (mean = 11.6; 6-17 years; SD = 3.5), were included in the study. Scapular positioning data were collected using a clinical assessment protocol including visual observation of titling and winging, measurement of forward shoulder posture, measurement of scapular upward rotation, and the Kinetic Medial Rotation Test (KMRT). The observation protocol for scapular winging and tilting did not show significant differences between adults and children. After controlling for height, forward shoulder posture (relaxed (0.28 cm/cm (0.06) vs. 0.31 cm/cm (0.07) and retracted (0.15 cm/cm (0.05) vs. 0.20 cm/cm (0.06)) were significantly smaller in children than in adults (P < 0.01). In addition, children showed greater scapular upward rotation (18.6°; SD 9.6°) than adults (14.5°; SD 10.9°) at 90° shoulder abduction. No significant differences were seen between children (19% positive test) and adults (24% positive test) using the KMRT. Children and adults show significant but small differences in scapular upward rotation and forward shoulder posture. These data provide useful reference values using a clinical protocol. Copyright © 2010 Elsevier Ltd. All rights reserved.

Predictive value of background experiences and visual spatial ability testing on laparoscopic baseline performance among residents entering postgraduate surgical training.

PubMed

Louridas, Marisa; Quinn, Lauren E; Grantcharov, Teodor P

2016-03-01

Emerging evidence suggests that despite dedicated practice, not all surgical trainees have the ability to reach technical competency in minimally invasive techniques. While selecting residents that have the ability to reach technical competence is important, evidence to guide the incorporation of technical ability into selection processes is limited. Therefore, the purpose of the present study was to evaluate whether background experiences and 2D-3D visual spatial test results are predictive of baseline laparoscopic skill for the novice surgical trainee. First-year residents were studied. Demographic data and background surgical and non-surgical experiences were obtained using a questionnaire. Visual spatial ability was evaluated using the PicSOr, cube comparison (CC) and card rotation (CR) tests. Technical skill was assessed using the camera navigation (LCN) task and laparoscopic circle cut (LCC) task. Resident performance on these technical tasks was compared and correlated with the questionnaire and visual spatial findings. Previous experience in observing laparoscopic procedures was associated with significantly better LCN performance, and experience in navigating the laparoscopic camera was associated with significantly better LCC task results. Residents who scored higher on the CC test demonstrated a more accurate LCN path length score (r s(PL) = -0.36, p = 0.03) and angle path (r s(AP) = -0.426, p = 0.01) score when completing the LCN task. No other significant correlations were found between the visual spatial tests (PicSOr, CC or CR) and LCC performance. While identifying selection tests for incoming surgical trainees that predict technical skill performance is appealing, the surrogate markers evaluated correlate with specific metrics of surgical performance related to a single task but do not appear to reliably predict technical performance of different laparoscopic tasks. Predicting the acquisition of technical skills will require the development of a series of evidence-based tests that measure a number of innate abilities as well as their inherent interactions.

Simulation and training of lumbar punctures using haptic volume rendering and a 6DOF haptic device

NASA Astrophysics Data System (ADS)

Färber, Matthias; Heller, Julika; Handels, Heinz

2007-03-01

The lumbar puncture is performed by inserting a needle into the spinal chord of the patient to inject medicaments or to extract liquor. The training of this procedure is usually done on the patient guided by experienced supervisors. A virtual reality lumbar puncture simulator has been developed in order to minimize the training costs and the patient's risk. We use a haptic device with six degrees of freedom (6DOF) to feedback forces that resist needle insertion and rotation. An improved haptic volume rendering approach is used to calculate the forces. This approach makes use of label data of relevant structures like skin, bone, muscles or fat and original CT data that contributes information about image structures that can not be segmented. A real-time 3D visualization with optional stereo view shows the punctured region. 2D visualizations of orthogonal slices enable a detailed impression of the anatomical context. The input data consisting of CT and label data and surface models of relevant structures is defined in an XML file together with haptic rendering and visualization parameters. In a first evaluation the visible human male data has been used to generate a virtual training body. Several users with different medical experience tested the lumbar puncture trainer. The simulator gives a good haptic and visual impression of the needle insertion and the haptic volume rendering technique enables the feeling of unsegmented structures. Especially, the restriction of transversal needle movement together with rotation constraints enabled by the 6DOF device facilitate a realistic puncture simulation.

Effect of Target Location on Dynamic Visual Acuity During Passive Horizontal Rotation

NASA Technical Reports Server (NTRS)

Appelbaum, Meghan; DeDios, Yiri; Kulecz, Walter; Peters, Brian; Wood, Scott

2010-01-01

The vestibulo-ocular reflex (VOR) generates eye rotation to compensate for potential retinal slip in the specific plane of head movement. Dynamic visual acuity (DVA) has been utilized as a functional measure of the VOR. The purpose of this study was to examine changes in accuracy and reaction time when performing a DVA task with targets offset from the plane of rotation, e.g. offset vertically during horizontal rotation. Visual acuity was measured in 12 healthy subjects as they moved a hand-held joystick to indicate the orientation of a computer-generated Landolt C "as quickly and accurately as possible." Acuity thresholds were established with optotypes presented centrally on a wall-mounted LCD screen at 1.3 m distance, first without motion (static condition) and then while oscillating at 0.8 Hz (DVA, peak velocity 60 deg/s). The effect of target location was then measured during horizontal rotation with the optotypes randomly presented in one of nine different locations on the screen (offset up to 10 deg). The optotype size (logMar 0, 0.2 or 0.4, corresponding to Snellen range 20/20 to 20/50) and presentation duration (150, 300 and 450 ms) were counter-balanced across five trials, each utilizing horizontal rotation at 0.8 Hz. Dynamic acuity was reduced relative to static acuity in 7 of 12 subjects by one step size. During the random target trials, both accuracy and reaction time improved proportional to optotype size. Accuracy and reaction time also improved between 150 ms and 300 ms presentation durations. The main finding was that both accuracy and reaction time varied as a function of target location, with greater performance decrements when acquiring vertical targets. We conclude that dynamic visual acuity varies with target location, with acuity optimized for targets in the plane of motion. Both reaction time and accuracy are functionally relevant DVA parameters of VOR function.

Simulation of Alpha Particles in Rotating Plasma Interacting with a Stationary Ripple

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abraham J. Fetterman and Nathaniel J. Fisch

Superthermal ExB rotation can provide magnetohydrodynamic (MHD) stability and enhanced confinement to axisymmetric mirrors. However, the rotation speed has been limited by phenomena at end electrodes. A new prediction is that rotation might instead be produced using a magnetic ripple and alpha particle kinetic energy, in an extension of the alpha channeling concept. The interaction of alpha particles with the ripple results in visually interesting and practically useful orbits.

The effect of attention loading on the inhibition of choice reaction time to visual motion by concurrent rotary motion

NASA Technical Reports Server (NTRS)

Looper, M.

1976-01-01

This study investigates the influence of attention loading on the established intersensory effects of passive bodily rotation on choice reaction time (RT) to visual motion. Subjects sat at the center of rotation in an enclosed rotating chamber and observed an oscilloscope on which were, in the center, a tracking display and, 10 deg left of center, a RT line. Three tracking tasks and a no-tracking control condition were presented to all subjects in combination with the RT task, which occurred with and without concurrent cab rotations. Choice RT to line motions was inhibited (probability less than .001) both when there was simultaneous vestibular stimulation and when there was a tracking task; response latencies lengthened progressively with increased similarity between the RT and tracking tasks. However, the attention conditions did not affect the intersensory effect; the significance of this for the nature of the sensory interaction is discussed.

Dynamic polarization vision in mantis shrimps

PubMed Central

Daly, Ilse M.; How, Martin J.; Partridge, Julian C.; Temple, Shelby E.; Marshall, N. Justin; Cronin, Thomas W.; Roberts, Nicholas W.

2016-01-01

Gaze stabilization is an almost ubiquitous animal behaviour, one that is required to see the world clearly and without blur. Stomatopods, however, only fix their eyes on scenes or objects of interest occasionally. Almost uniquely among animals they explore their visual environment with a series pitch, yaw and torsional (roll) rotations of their eyes, where each eye may also move largely independently of the other. In this work, we demonstrate that the torsional rotations are used to actively enhance their ability to see the polarization of light. Both Gonodactylus smithii and Odontodactylus scyllarus rotate their eyes to align particular photoreceptors relative to the angle of polarization of a linearly polarized visual stimulus, thereby maximizing the polarization contrast between an object of interest and its background. This is the first documented example of any animal displaying dynamic polarization vision, in which the polarization information is actively maximized through rotational eye movements. PMID:27401817

Control of low-speed turbulent separated flow over a backward-facing ramp. Ph.D. Thesis - Old Dominion Univ.

NASA Technical Reports Server (NTRS)

Lin, John C.

1992-01-01

The relative performance and flow phenomena associated with several devices for controlling turbulent separated flow were investigated at low speeds. Relative performance of the devices was examined for flow over a curved, backward-facing ramp in a wind tunnel, and the flow phenomena were examined in a water tunnel using dye-flow visualization. Surface static pressure measurements and oil-flow visualization results from the wind tunnel tests indicated that transverse grooves, longitudinal grooves, submerged vortex generators, vortex generator jets (VGJ's), Viets' fluidic flappers, elongated arches at positive angle of attack, and large-eddy breakup devices (LEBU's) at positive angle of attack placed near the baseline separation location reduce flow separation and increase pressure recovery. Spanwise cylinders reduce flow separation but decrease pressure recovery downstream. Riblets, passive porous surfaces, swept grooves, Helmholtz resonators, and arches and LEBU's with angle of attack less than or = 0 degrees had no significant effect in reducing the extent of the separation region. Wall-cooling computations indicated that separation delay on a partially-cooled ramp is nearly the same as on a fully-cooled ramp, while minimizing the frictional drag increase associated with the wall cooling process. Dry-flow visualization tests in the water tunnel indicated that wishbone vortex generators in the forward orientation shed horseshoe vortices; wishbone vortex generators oriented in the reverse direction and doublet vortex generators shed streamwise counterrotating vortices; a spanewise cylinder located near the wall and LEBU's at angle of attack = -10 degrees produced eddies or transverse vortices which rotated with the same sign as the mean vorticity in a turbulent boundary layer; and the most effective VGJ's produced streamwise co-rotating vortices. Comparative wind-tunnel test results indicated that transferring momentum from the outer region of a turbulent boundary layer through the action of embedded streamwise vortices is more effective than by transverse vortices for the separation control application studied herein.

You Should Be the Specialist! Weak Mental Rotation Performance in Aviation Security Screeners – Reduced Performance Level in Aviation Security with No Gender Effect

PubMed Central

Krüger, Jenny K.; Suchan, Boris

2016-01-01

Aviation security screeners analyze a large number of X-ray images per day and seem to be experts in mentally rotating diverse kinds of visual objects. A robust gender-effect that men outperform women in the Vandenberg & Kuse mental rotation task has been well documented over the last years. In addition it has been shown that training can positively influence the overall task-performance. Considering this, the aim of the present study was to investigate whether security screeners show better performance in the Mental Rotation Test (MRT) independently of gender. Forty-seven security screeners of both sexes from two German airports were examined with a computer based MRT. Their performance was compared to a large sample of control subjects. The well-known gender-effect favoring men on mental rotation was significant within the control group. However, the security screeners did not show any sex differences suggesting an effect of training and professional performance. Surprisingly this specialized group showed a lower level of overall MRT performance than the control participants. Possible aviation related influences such as secondary effects of work-shift or expertise which can cumulatively cause this result are discussed. PMID:27014142

Spatio-temporal brain activity related to rotation method during a mental rotation task of three-dimensional objects: an MEG study.

PubMed

Kawamichi, Hiroaki; Kikuchi, Yoshiaki; Ueno, Shoogo

2007-09-01

During mental rotation tasks, subjects perform mental simulation to solve tasks. However, detailed neural mechanisms underlying mental rotation of three-dimensional (3D) objects, particularly, whether higher motor areas related to mental simulation are activated, remain unknown. We hypothesized that environmental monitoring-a process based on environmental information and is included in motor execution-is as a key factor affecting the utilization of higher motor areas. Therefore, using magnetoencephalography (MEG), we measured spatio-temporal brain activities during two types (two-dimensional (2D) and 3D rotation tasks) of mental rotation of 3D objects. Only the 3D rotation tasks required subjects to mentally rotate objects in a depth plane with visualization of hidden parts of the visual stimuli by acquiring and retrieving 3D information. In cases showing significant differences in the averaged activities at 100-ms intervals between the two rotations, the activities were located in the right dorsal premotor (PMd) at approximately 500 ms. In these cases, averaged activities during 3D rotation were greater than those during 2D rotation, implying that the right PMd activities are related to environmental monitoring. During 3D rotation, higher activities were observed from 200 to 300 ms in the left PMd and from 400 to 700 ms in the right PMd. It is considered that the left PMd is related to primary motor control, whereas the right PMd plays a supplementary role during mental simulation. Further, during 3D rotation, late higher activities related to mental simulation are observed in the right superior parietal lobule (SPL), which is connected to PMd.

Translational head movements of pigeons in response to a rotating pattern: characteristics and tool to analyse mechanisms underlying detection of rotational and translational optical flow.

PubMed

Nalbach, H O

1992-01-01

Pigeons freely standing in the centre of a two-dimensionally textured cylinder not only rotate but also laterally translate their head in response to the pattern sinusoidally oscillating or unidirectionally rotating around their vertical axis. The translational head movement dominates the response at high oscillation frequencies, whereas in a unidirectionally rotating drum head translation declines at about the same rate as the rotational response increases. It is suggested that this is a consequence of charging the 'velocity storage' in the vestibulo-ocular system. Similar to the rotational head movement (opto-collic reflex), the translational head movement is elicited via a wide-field motion sensitive system. The underlying mechanism can be described as vector integration of movement vectors tangential to the pattern rotation. Stimulation of the frontal visual field elicits largest translational responses while rotational responses can be elicited equally well from any azimuthal position of a moving pattern. Experiments where most of the pattern is occluded by a screen and the pigeon is allowed to view the stimulus through one or two windows demonstrate a short-range inhibition and long-range excitation between movement detectors that feed into the rotational system. Furthermore, the results obtained from such types of experiments suggest that the rotational system inhibits the translational system. These mechanisms may help the pigeon to decompose image flow into its translational and rotational components. Because of their translational response to a rotational stimulus, it is concluded, however, that pigeons either generally cannot perfectly perform the task or they need further visual information, like differential image motion, that was not available to them in the paradigms.

Comparison of the visual and intraocular optical performance of a refractive multifocal IOL with rotational asymmetry and an apodized diffractive multifocal IOL.

PubMed

Alió, Jorge L; Plaza-Puche, Ana B; Javaloy, Jaime; Ayala, María José

2012-02-01

To compare the visual outcomes and intraocular optical quality observed postoperatively in patients implanted with a rotationally asymmetric multifocal intraocular lens (IOL) and an apodized diffractive multifocal IOL. Seventy-four consecutive eyes of 40 cataract patients (age range: 36 to 79 years) were divided into two groups: zonal refractive group, 39 eyes implanted with a rotationally asymmetric multifocal IOL (Lentis Mplus LS-312 IOL, Oculentis GmbH); and diffractive group, 35 eyes implanted with an apodized diffractive multifocal IOL (ReSTOR SN6AD3, Alcon Laboratories Inc). Distance and near visual acuity outcomes, contrast sensitivity, intraocular optical quality, and defocus curves were evaluated during 3-month follow-up. Calculation of the intraocular aberrations was performed by subtracting corneal aberrations from total ocular aberrations. Uncorrected near visual acuity and distance-corrected near visual acuity were better in the diffractive group than in the zonal refractive group (P=.01), whereas intermediate visual acuity (defocus +1.00 and +1.50 diopters) was better in the zonal refractive group. Photopic contrast sensitivity was significantly better in the zonal refractive group (P=.04). Wavefront aberrations (total, higher order, tilt, primary coma) were significantly higher in the zonal refractive group than in the diffractive group (P=.02). Both multifocal IOLs are able to successfully restore visual function after cataract surgery. The zonal refractive multifocal IOL provides better results in contrast sensitivity and intermediate vision, whereas the diffractive multifocal IOL provides better near vision at a closer distance. Copyright 2012, SLACK Incorporated.

Spatial attention improves reliability of fMRI retinotopic mapping signals in occipital and parietal cortex

PubMed Central

Bressler, David W.; Silver, Michael A.

2010-01-01

Spatial attention improves visual perception and increases the amplitude of neural responses in visual cortex. In addition, spatial attention tasks and fMRI have been used to discover topographic visual field representations in regions outside visual cortex. We therefore hypothesized that requiring subjects to attend to a retinotopic mapping stimulus would facilitate the characterization of visual field representations in a number of cortical areas. In our study, subjects attended either a central fixation point or a wedge-shaped stimulus that rotated about the fixation point. Response reliability was assessed by computing coherence between the fMRI time series and a sinusoid with the same frequency as the rotating wedge stimulus. When subjects attended to the rotating wedge instead of ignoring it, the reliability of retinotopic mapping signals increased by approximately 50% in early visual cortical areas (V1, V2, V3, V3A/B, V4) and ventral occipital cortex (VO1) and by approximately 75% in lateral occipital (LO1, LO2) and posterior parietal (IPS0, IPS1 and IPS2) cortical areas. Additionally, one 5-minute run of retinotopic mapping in the attention-to-wedge condition produced responses as reliable as the average of three to five (early visual cortex) or more than five (lateral occipital, ventral occipital, and posterior parietal cortex) attention-to-fixation runs. These results demonstrate that allocating attention to the retinotopic mapping stimulus substantially reduces the amount of scanning time needed to determine the visual field representations in occipital and parietal topographic cortical areas. Attention significantly increased response reliability in every cortical area we examined and may therefore be a general mechanism for improving the fidelity of neural representations of sensory stimuli at multiple levels of the cortical processing hierarchy. PMID:20600961

Visuomotor adaptation to a visual rotation is gravity dependent.

PubMed

Toma, Simone; Sciutti, Alessandra; Papaxanthis, Charalambos; Pozzo, Thierry

2015-03-15

Humans perform vertical and horizontal arm motions with different temporal patterns. The specific velocity profiles are chosen by the central nervous system by integrating the gravitational force field to minimize energy expenditure. However, what happens when a visuomotor rotation is applied, so that a motion performed in the horizontal plane is perceived as vertical? We investigated the dynamic of the adaptation of the spatial and temporal properties of a pointing motion during prolonged exposure to a 90° visuomotor rotation, where a horizontal movement was associated with a vertical visual feedback. We found that participants immediately adapted the spatial parameters of motion to the conflicting visual scene in order to keep their arm trajectory straight. In contrast, the initial symmetric velocity profiles specific for a horizontal motion were progressively modified during the conflict exposure, becoming more asymmetric and similar to those appropriate for a vertical motion. Importantly, this visual effect that increased with repetitions was not followed by a consistent aftereffect when the conflicting visual feedback was absent (catch and washout trials). In a control experiment we demonstrated that an intrinsic representation of the temporal structure of perceived vertical motions could provide the error signal allowing for this progressive adaptation of motion timing. These findings suggest that gravity strongly constrains motor learning and the reweighting process between visual and proprioceptive sensory inputs, leading to the selection of a motor plan that is suboptimal in terms of energy expenditure. Copyright © 2015 the American Physiological Society.

Transient cardio-respiratory responses to visually induced tilt illusions

NASA Technical Reports Server (NTRS)

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.

Effect of visuomotor-map uncertainty on visuomotor adaptation.

PubMed

Saijo, Naoki; Gomi, Hiroaki

2012-03-01

Vision and proprioception contribute to generating hand movement. If a conflict between the visual and proprioceptive feedback of hand position is given, reaching movement is disturbed initially but recovers after training. Although previous studies have predominantly investigated the adaptive change in the motor output, it is unclear whether the contributions of visual and proprioceptive feedback controls to the reaching movement are modified by visuomotor adaptation. To investigate this, we focused on the change in proprioceptive feedback control associated with visuomotor adaptation. After the adaptation to gradually introduce visuomotor rotation, the hand reached the shifted position of the visual target to move the cursor to the visual target correctly. When the cursor feedback was occasionally eliminated (probe trial), the end point of the hand movement was biased in the visual-target direction, while the movement was initiated in the adapted direction, suggesting the incomplete adaptation of proprioceptive feedback control. Moreover, after the learning of uncertain visuomotor rotation, in which the rotation angle was randomly fluctuated on a trial-by-trial basis, the end-point bias in the probe trial increased, but the initial movement direction was not affected, suggesting a reduction in the adaptation level of proprioceptive feedback control. These results suggest that the change in the relative contribution of visual and proprioceptive feedback controls to the reaching movement in response to the visuomotor-map uncertainty is involved in visuomotor adaptation, whereas feedforward control might adapt in a manner different from that of the feedback control.

Chirality and Pinwheels

ERIC Educational Resources Information Center

Rodriguez-Fernandez, Emilio

2013-01-01

By using cardboard models that resemble propellers, the students of inorganic courses can easily visualizing the distinct rotation of optical isomers. These propellers rotate clockwise or counterclockwise when they are dropped from a certain height or in the presence of wind. (Contains 1 figure.)

Visual influence on path integration in darkness indicates a multimodal representation of large-scale space

PubMed Central

Tcheang, Lili; Bülthoff, Heinrich H.; Burgess, Neil

2011-01-01

Our ability to return to the start of a route recently performed in darkness is thought to reflect path integration of motion-related information. Here we provide evidence that motion-related interoceptive representations (proprioceptive, vestibular, and motor efference copy) combine with visual representations to form a single multimodal representation guiding navigation. We used immersive virtual reality to decouple visual input from motion-related interoception by manipulating the rotation or translation gain of the visual projection. First, participants walked an outbound path with both visual and interoceptive input, and returned to the start in darkness, demonstrating the influences of both visual and interoceptive information in a virtual reality environment. Next, participants adapted to visual rotation gains in the virtual environment, and then performed the path integration task entirely in darkness. Our findings were accurately predicted by a quantitative model in which visual and interoceptive inputs combine into a single multimodal representation guiding navigation, and are incompatible with a model of separate visual and interoceptive influences on action (in which path integration in darkness must rely solely on interoceptive representations). Overall, our findings suggest that a combined multimodal representation guides large-scale navigation, consistent with a role for visual imagery or a cognitive map. PMID:21199934

Micro-CT images reconstruction and 3D visualization for small animal studying

NASA Astrophysics Data System (ADS)

Gong, Hui; Liu, Qian; Zhong, Aijun; Ju, Shan; Fang, Quan; Fang, Zheng

2005-01-01

A small-animal x-ray micro computed tomography (micro-CT) system has been constructed to screen laboratory small animals and organs. The micro-CT system consists of dual fiber-optic taper-coupled CCD detectors with a field-of-view of 25x50 mm2, a microfocus x-ray source, a rotational subject holder. For accurate localization of rotation center, coincidence between the axis of rotation and centre of image was studied by calibration with a polymethylmethacrylate cylinder. Feldkamp"s filtered back-projection cone-beam algorithm is adopted for three-dimensional reconstruction on account of the effective corn-beam angle is 5.67° of the micro-CT system. 200x1024x1024 matrix data of micro-CT is obtained with the magnification of 1.77 and pixel size of 31x31μm2. In our reconstruction software, output image size of micro-CT slices data, magnification factor and rotation sample degree can be modified in the condition of different computational efficiency and reconstruction region. The reconstructed image matrix data is processed and visualization by Visualization Toolkit (VTK). Data parallelism of VTK is performed in surface rendering of reconstructed data in order to improve computing speed. Computing time of processing a 512x512x512 matrix datasets is about 1/20 compared with serial program when 30 CPU is used. The voxel size is 54x54x108 μm3. The reconstruction and 3-D visualization images of laboratory rat ear are presented.

Circular displays: control/display arrangements and stereotype strength with eight different display locations.

PubMed

Chan, Alan H S; Hoffmann, Errol R

2015-01-01

Two experiments are reported that were designed to investigate control/display arrangements having high stereotype strengths when using circular displays. Eight display locations relative to the operator and control were tested with rotational and translational controls situated on different planes according to the Frame of Reference Transformation Tool (FORT) model of Wickens et al. (2010). (Left. No, Right! Development of the Frame of Reference Transformation Tool (FORT), Proceedings of the Human Factors and Ergonomics Society 54th Annual Meeting, 54: 1022-1026). In many cases, there was little effect of display locations, indicating the importance of the Worringham and Beringer (1998. Directional stimulus-response compatibility: a test of three alternative principles. Ergonomics, 41(6), 864-880) Visual Field principle and an extension of this principle for rotary controls (Hoffmann and Chan (2013). The Worringham and Beringer 'visual field' principle for rotary controls. Ergonomics, 56(10), 1620-1624). The initial indicator position (12, 3, 6 and 9 o'clock) had a major effect on control/display stereotype strength for many of the six controls tested. Best display/control arrangements are listed for each of the different control types (rotational and translational) and for the planes on which they are mounted. Data have application where a circular display is used due to limited display panel space and applies to space-craft, robotics operators, hospital equipment and home appliances. Practitioner Summary: Circular displays are often used when there is limited space available on a control panel. Display/control arrangements having high stereotype strength are listed for four initial indicator positions. These arrangements are best for design purposes.

Massachusetts Institute of Technology Consortium Agreement. Phase II

DTIC Science & Technology

1999-03-01

Portable VOR Testing Apparatusthe visual target. Head movements are monitored with magneto-hydrodynamic rotational velocity sensors , and eye motions are...Zhang 4. Miniaturization of the Ring Sensor B-H Yang, H. Asada, K-W. Chang , S. Rhee, Y. Zhang 5. SIMSUIT and Biochair Projects L. Jones, J. Tangorra...No change along 0 a•0a = (2) Neglect Vr = Vr = 0 (Wall velocity of r direction is very small compared with v.’.) a ax ax= (3) As r << x, Dr• >> axx

Adaptation of the vestibulo-ocular reflex for forward-eyed foveate vision

PubMed Central

Migliaccio, Americo A; Minor, Lloyd B; Santina, Charles C Della

2010-01-01

To maintain visual fixation on a distant target during head rotation, the angular vestibulo-ocular reflex (aVOR) should rotate the eyes at the same speed as the head and in exactly the opposite direction. However, in primates for which the 3-dimensional (3D) aVOR has been extensively characterised (humans and squirrel monkeys (Saimiri sciureus)), the aVOR response to roll head rotation about the naso-occipital axis is lower than that elicited by yaw and pitch, causing errors in aVOR magnitude and direction that vary with the axis of head rotation. In other words, primates keep the central part of the retinal image on the fovea (where photoreceptor density and visual acuity are greatest) but fail to keep that image from twisting about the eyes' resting optic axes. We tested the hypothesis that aVOR direction dependence is an adaptation related to primates' frontal-eyed, foveate status through comparison with the aVOR of a lateral-eyed, afoveate mammal (Chinchilla lanigera). As chinchillas' eyes are afoveate and never align with each other, we predicted that the chinchilla aVOR would be relatively low in gain and isotropic (equal in gain for every head rotation axis). In 11 normal chinchillas, we recorded binocular 3D eye movements in darkness during static tilts, 20–100 deg s−1 whole-body sinusoidal rotations (0.5–15 Hz), and 3000 deg s−2 acceleration steps. Although the chinchilla 3D aVOR gain changed with both frequency and peak velocity over the range we examined, we consistently found that it was more nearly isotropic than the primate aVOR. Our results suggest that primates' anisotropic aVOR represents an adaptation to their forward-eyed, foveate status. In primates, yaw and pitch aVOR must be compensatory to stabilise images on both foveae, whereas roll aVOR can be under-compensatory because the brain tolerates torsion of binocular images that remain on the foveae. In contrast, the lateral-eyed chinchilla faces different adaptive demands and thus enlists a different aVOR strategy. PMID:20724359

A comparison of VRML and animation of rotation for teaching 3-dimensional crystal lattice structures

NASA Astrophysics Data System (ADS)

Sauls, Barbara Lynn

Chemistry students often have difficulty visualizing abstract concepts of molecules and atoms, which may lead to misconceptions. The three-dimensionality of these structures presents a challenge to educators. Typical methods of teaching include text with two-dimensional graphics and structural models. Improved methods to allow visualization of 3D structures may improve learning of these concepts. This research compared the use of Virtual Reality Modeling Language (VRML) and animation of rotation for teaching three-dimensional structures. VRML allows full control of objects by altering angle, size, rotation, and provides the ability to zoom into and through objects. Animations may only be stopped, restarted and replayed. A web-based lesson teaching basic concepts of crystals, which requires comprehension of their three-dimensional structure was given to 100 freshmen chemistry students. Students were stratified by gender then randomly to one of two lessons, which were identical except for the multimedia method used to show the lattices and unit cells. One method required exploration of the structures using VRML, the other provided animations of the same structures rotating. The students worked through an examination as the lesson progressed. A Welch t' test was used to compare differences between groups. No significant difference in mean achievement was found between the two methods, between genders, or within gender. There was no significant difference in mean total SAT in the animation and VRML group. Total time on task had no significant difference nor did enjoyment of the lesson. Students, however, spent 14% less time maneuvering VRML structures than viewing the animations of rotation. Neither method proved superior for presenting three-dimensional information. The students spent less time maneuvering the VRML structures with no difference in mean score so the use of VRML may be more efficient. The investigator noted some manipulation difficulties using VRML to rotate structures. Some students had difficulty obtaining the correct angle required to properly interpret spatial relationships. This led to frustration and caused some students to quit trying before they could answer questions fully. Even though there were some difficulties, outcomes were not affected. Higher scores, however, may have been achieved had the students been proficient in VRML maneuvering.

Experience affects the use of ego-motion signals during 3D shape perception

PubMed Central

Jain, Anshul; Backus, Benjamin T.

2011-01-01

Experience has long-term effects on perceptual appearance (Q. Haijiang, J. A. Saunders, R. W. Stone, & B. T. Backus, 2006). We asked whether experience affects the appearance of structure-from-motion stimuli when the optic flow is caused by observer ego-motion. Optic flow is an ambiguous depth cue: a rotating object and its oppositely rotating, depth-inverted dual generate similar flow. However, the visual system exploits ego-motion signals to prefer the percept of an object that is stationary over one that rotates (M. Wexler, F. Panerai, I. Lamouret, & J. Droulez, 2001). We replicated this finding and asked whether this preference for stationarity, the “stationarity prior,” is modulated by experience. During training, two groups of observers were exposed to objects with identical flow, but that were either stationary or moving as determined by other cues. The training caused identical test stimuli to be seen preferentially as stationary or moving by the two groups, respectively. We then asked whether different priors can exist independently at different locations in the visual field. Observers were trained to see objects either as stationary or as moving at two different locations. Observers’ stationarity bias at the two respective locations was modulated in the directions consistent with training. Thus, the utilization of extraretinal ego-motion signals for disambiguating optic flow signals can be updated as the result of experience, consistent with the updating of a Bayesian prior for stationarity. PMID:21191132

Using relative velocity vectors to reveal axial rotation about the medial and lateral compartment of the knee.

PubMed

Anderst, William J; Tashman, Scott

2010-03-22

A new technique is presented that utilizes relative velocity vectors between articulating surfaces to characterize internal/external rotation of the tibio-femoral joint during dynamic loading. Precise tibio-femoral motion was determined by tracking the movement of implanted tantalum beads in high-speed biplane X-rays. Three-dimensional, subject-specific CT reconstructions of the femur and tibia, consisting of triangular mesh elements, were positioned in each analyzed frame. The minimum distance between subchondral bone surfaces was recorded for each mesh element comprising each bone surface, and the relative velocity between these opposing closest surface elements was determined in each frame. Internal/external rotation was visualized by superimposing tangential relative velocity vectors onto bone surfaces at each instant. Rotation about medial and lateral compartments was quantified by calculating the angle between these tangential relative vectors within each compartment. Results acquired from 68 test sessions involving 23 dogs indicated a consistent pattern of sequential rotation about the lateral condyle (approximately 60 ms after paw strike) followed by rotation about the medial condyle (approximately 100 ms after paw strike). These results imply that axial knee rotation follows a repeatable pattern within and among subjects. This pattern involves rotation about both the lateral and medial compartments. The technique described can be easily applied to study human knee internal/external rotation during a variety of activities. This information may be useful to define normal and pathologic conditions, to confirm post-surgical restoration of knee mechanics, and to design more realistic prosthetic devices. Furthermore, analysis of joint arthrokinematics, such as those described, may identify changes in joint mechanics associated with joint degeneration. Copyright (c) 2009 Elsevier Ltd. All rights reserved.

Sleep disturbance associated with rotator cuff tear: correction with arthroscopic rotator cuff repair.

PubMed

Austin, Luke; Pepe, Matthew; Tucker, Bradford; Ong, Alvin; Nugent, Robert; Eck, Brandon; Tjoumakaris, Fotios

2015-06-01

Sleep disturbance is a common complaint of patients with a rotator cuff tear. Inadequate and restless sleep, along with pain, is often a driving symptom for patients to proceed with rotator cuff repair. To date, no studies have examined sleep disturbance in patients undergoing rotator cuff repair, and there is no evidence that surgery improves sleep disturbance. Sleep disturbance is prevalent in patients with a symptomatic rotator cuff tear, and sleep disturbance improves after arthroscopic rotator cuff repair. Case series; Level of evidence, 4. A total of 56 patients undergoing arthroscopic rotator cuff repair for full-thickness tears were enrolled in a prospective study. Patients were surveyed preoperatively and postoperatively at intervals of 2, 6, 12, 18, and 24 weeks. Patient outcomes were scored using the Pittsburgh Sleep Quality Index (PSQI), Simple Shoulder Test (SST), visual analog scale for pain (VAS), and single assessment numeric evaluation (SANE). Demographic and surgical factors were also collected for analysis. Preoperative PSQI scores indicative of sleep disturbance were reported in 89% of patients. After surgery, a statistically significant improvement in PSQI was achieved at 3 months (P = .0012; 91% follow-up) and continued through 6 months (P = .0179; 93% follow-up). Six months after surgery, only 38% of patients continued to have sleep disturbance. Multivariable linear regression of all surgical and demographic factors versus PSQI was performed and demonstrated that preoperative and prolonged postoperative narcotic use negatively affected sleep. Sleep disturbance is common in patients undergoing rotator cuff repair. After surgery, sleep disturbance improves to levels comparable with those of the general public. Preoperative and prolonged postoperative use of narcotic pain medication negatively affects sleep. © 2015 The Author(s).

Interactive Design and Visualization of Branched Covering Spaces.

PubMed

Roy, Lawrence; Kumar, Prashant; Golbabaei, Sanaz; Zhang, Yue; Zhang, Eugene

2018-01-01

Branched covering spaces are a mathematical concept which originates from complex analysis and topology and has applications in tensor field topology and geometry remeshing. Given a manifold surface and an -way rotational symmetry field, a branched covering space is a manifold surface that has an -to-1 map to the original surface except at the ramification points, which correspond to the singularities in the rotational symmetry field. Understanding the notion and mathematical properties of branched covering spaces is important to researchers in tensor field visualization and geometry processing, and their application areas. In this paper, we provide a framework to interactively design and visualize the branched covering space (BCS) of an input mesh surface and a rotational symmetry field defined on it. In our framework, the user can visualize not only the BCSs but also their construction process. In addition, our system allows the user to design the geometric realization of the BCS using mesh deformation techniques as well as connecting tubes. This enables the user to verify important facts about BCSs such as that they are manifold surfaces around singularities, as well as the Riemann-Hurwitz formula which relates the Euler characteristic of the BCS to that of the original mesh. Our system is evaluated by student researchers in scientific visualization and geometry processing as well as faculty members in mathematics at our university who teach topology. We include their evaluations and feedback in the paper.

Transient dichroism in photoreceptor membranes indicates that stable oligomers of rhodopsin do not form during excitation.

PubMed Central

Downer, N W; Cone, R A

1985-01-01

If a photoexcited rhodopsin molecule initiates the formation of rhodopsin oligomers during the process of visual excitation, the rate of rotational diffusion of the rhodopsin molecules involved should change markedly. Using microsecond-flash photometry, we have observed the rotational diffusion of rhodopsin throughout the time period of visual excitation and found that no detectable change occurs in its rotational diffusion rate. Partial chemical cross-linking of the retina yields oligomers of rhodopsin and causes a significant decrease in the rotational diffusion rate of rhodopsin even when as little as 20% of rhodopsin is dimeric. Moreover, the pattern of oligomers formed by cross-linking, taken together with the magnitude of decreases in rotational diffusion rate accompanying the cross-linking reaction, suggests that rhodopsin is a monomer in the dark-adapted state. The experiments reported here show that photoexcited rhodopsin molecules do not irreversibly associate with unbleached neighbors during the time course of the receptor response. Hence, it is not likely that stable oligomers of rhodopsin trigger the excitation of the photoreceptor cell. Images FIGURE 1 PMID:3919778

Peak firing rates of rat anterodorsal thalamic head direction cells are higher during faster passive rotations.

PubMed

Zugaro, Michaël B; Berthoz, Alain; Wiener, Sidney I

2002-01-01

Head direction cells discharge selectively when the head of the animal is oriented in a specific direction. The goal of this study was to determine how sensory signals arising from passive rotations (e.g., triggered by vestibular stimulation and dynamic visual inputs) influence the responses of anterodorsal thalamic head direction cells in the absence of voluntary movement cues (e.g., motor command, efference copy, and associated kinesthetic signals). Three unrestrained rats consumed water from a reservoir at the center of a circular platform while passively subjected to sinusoidal rotatory oscillations at fast (153 +/- 27 degrees/s, sd) and slow (38 +/- 15 degrees/s) peak velocities. In 14 anterodorsal thalamic head direction cells, the preferred directions, angular response ranges and baseline firing rates remained stable, but the peak firing rates were, on average, 36% higher during the fast rotations (Wilcoxon matched-pairs test, p < 0.001; variation range: +11% to approximately +100%). No cell changed its peak firing rate by less than 10%, while three cells (21%) increased their peak firing rates by more than 50%. The velocity-dependent increase in peak firing rates was similar for left and right rotations, and the skewness of the directional response curves were not significantly different between left and right turns (Wilcoxon matched-pairs tests, n = 14, ns). These results show that sensory signals concerning self-movements modulate the responses of the head direction cells in the absence of active locomotion.

Tracking single-particle rotation during macrophage uptake

DOE PAGES

Sanchez, Lucero; Patton, Paul; Anthony, Stephen Michael; ...

2015-06-10

We investigated the rotational dynamics of single microparticles during their internalization by macrophage cells. The microparticles used were triblock patchy particles that display two fluorescent patches on their two poles. The optical anisotropy made it possible to directly visualize and quantify the orientation and rotation of the particles. We show that particles exhibit a mixture of fast and slow rotation as they are uptaken by macrophages and transiently undergo directional rotation during their entry into the cell. As a result, the size of the particles and the surface presentation of ligands exerted a negligible influence on this heterogeneity of particlemore » rotation.« less

The use of embodied self-rotation for visual and spatial perspective-taking

PubMed Central

Surtees, Andrew; Apperly, Ian; Samson, Dana

2013-01-01

Previous research has shown that calculating if something is to someone’s left or right involves a simulative process recruiting representations of our own body in imagining ourselves in the position of the other person (Kessler and Rutherford, 2010). We compared left and right judgements from another’s spatial position (spatial perspective judgements) to judgements of how a numeral appeared from another’s point of view (visual perspective judgements). Experiment 1 confirmed that these visual and spatial perspective judgements involved a process of rotation as they became more difficult with angular disparity between the self and other. There was evidence of some difference between the two, but both showed a linear pattern. Experiment 2 went a step further in showing that these judgements used embodied self rotations, as their difficulty was also dependent on the current position of the self within the world. This effect was significantly stronger in spatial perspective-taking, but was present in both cases. We conclude that embodied self-rotations, through which we actively imagine ourselves assuming someone else’s position in the world can subserve not only reasoning about where objects are in relation to someone else but also how the objects in their environment appear to them. PMID:24204334

A Causal Role for V5/MT Neurons Coding Motion-Disparity Conjunctions in Resolving Perceptual Ambiguity

PubMed Central

Krug, Kristine; Cicmil, Nela; Parker, Andrew J.; Cumming, Bruce G.

2013-01-01

Summary Judgments about the perceptual appearance of visual objects require the combination of multiple parameters, like location, direction, color, speed, and depth. Our understanding of perceptual judgments has been greatly informed by studies of ambiguous figures, which take on different appearances depending upon the brain state of the observer. Here we probe the neural mechanisms hypothesized as responsible for judging the apparent direction of rotation of ambiguous structure from motion (SFM) stimuli. Resolving the rotation direction of SFM cylinders requires the conjoint decoding of direction of motion and binocular depth signals [1, 2]. Within cortical visual area V5/MT of two macaque monkeys, we applied electrical stimulation at sites with consistent multiunit tuning to combinations of binocular depth and direction of motion, while the monkey made perceptual decisions about the rotation of SFM stimuli. For both ambiguous and unambiguous SFM figures, rotation judgments shifted as if we had added a specific conjunction of disparity and motion signals to the stimulus elements. This is the first causal demonstration that the activity of neurons in V5/MT contributes directly to the perception of SFM stimuli and by implication to decoding the specific conjunction of disparity and motion, the two different visual cues whose combination drives the perceptual judgment. PMID:23871244

In touch with mental rotation: interactions between mental and tactile rotations and motor responses.

PubMed

Lohmann, Johannes; Rolke, Bettina; Butz, Martin V

2017-04-01

Although several process models have described the cognitive processing stages that are involved in mentally rotating objects, the exact nature of the rotation process itself remains elusive. According to embodied cognition, cognitive functions are deeply grounded in the sensorimotor system. We thus hypothesized that modal rotation perceptions should influence mental rotations. We conducted two studies in which participants had to judge if a rotated letter was visually presented canonically or mirrored. Concurrently, participants had to judge if a tactile rotation on their palm changed direction during the trial. The results show that tactile rotations can systematically influence mental rotation performance in that same rotations are favored. In addition, the results show that mental rotations produce a response compatibility effect: clockwise mental rotations facilitate responses to the right, while counterclockwise mental rotations facilitate responses to the left. We conclude that the execution of mental rotations activates cognitive mechanisms that are also used to perceive rotations in different modalities and that are associated with directional motor control processes.

Effects of asymptomatic rotator cuff pathology on in vivo shoulder motion and clinical outcomes.

PubMed

Baumer, Timothy G; Dischler, Jack; Mende, Veronica; Zauel, Roger; van Holsbeeck, Marnix; Siegal, Daniel S; Divine, George; Moutzouros, Vasilios; Bey, Michael J

2017-06-01

The incidence of asymptomatic rotator cuff tears has been reported to range from 15% to 39%, but the influence of asymptomatic rotator cuff pathology on shoulder function is not well understood. This study assessed the effects of asymptomatic rotator cuff pathology on shoulder kinematics, strength, and patient-reported outcomes. A clinical ultrasound examination was performed in 46 asymptomatic volunteers (age: 60.3 ± 7.5 years) with normal shoulder function to document the condition of their rotator cuff. The ultrasound imaging identified the participants as healthy (n = 14) or pathologic (n = 32). Shoulder motion was measured with a biplane x-ray imaging system, strength was assessed with a Biodex (Biodex Medical Systems, Inc., Shirley, NY, USA), and patient-reported outcomes were assessed using the Western Ontario Rotator Cuff Index and visual analog scale pain scores. Compared with healthy volunteers, those with rotator cuff pathology had significantly less abduction (P = .050) and elevation (P = .041) strength, their humerus was positioned more inferiorly on the glenoid (P = .018), and the glenohumeral contact path length was longer (P = .007). No significant differences were detected in the Western Ontario Rotator Cuff Index, visual analog scale, range of motion, or acromiohumeral distance. The differences observed between the healthy volunteers and those with asymptomatic rotator cuff pathology lend insight into the changes in joint mechanics, shoulder strength, and conventional clinical outcomes associated with the early stages of rotator cuff pathology. Furthermore, these findings suggest a plausible mechanical progression of kinematic and strength changes associated with the development of rotator cuff pathology. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Block ground interaction of rockfalls

NASA Astrophysics Data System (ADS)

Volkwein, Axel; Gerber, Werner; Kummer, Peter

2016-04-01

During a rockfall the interaction of the falling block with the ground is one of the most important factors that define the evolution of a rockfall trajectory. It steers the rebound, the rotational movement, possibly brake effects, friction losses and damping effects. Therefore, if most reliable rockfall /trajectory simulation software is sought a good understanding of the block ground interaction is necessary. Today's rockfall codes enable the simulation of a fully 3D modelled block within a full 3D surface . However, the details during the contact, i.e. the contact duration, the penetration depth or the dimension of the marks in the ground are usually not part of the simulation. Recent field tests with rocks between 20 and 80 kg have been conducted on a grassy slope in 2014 [1]. A special rockfall sensor [2] within the blocks measured the rotational velocity and the acting accelerations during the tests. External video records and a so-called LocalPositioningSystem deliver information on the travel velocity. With these data not only the flight phases of the trajectories but also the contacts with the ground can be analysed. During the single jumps of a block the flight time, jump length, the velocity, and the rotation are known. During the single impacts their duration and the acting accelerations are visible. Further, the changes of rotational and translational velocity influence the next jump of the block. The change of the rotational velocity over the whole trajectory nicely visualizes the different phases of a rockfall regarding general acceleration and deceleration in respect to the inclination and the topography of the field. References: [1] Volkwein A, Krummenacher B, Gerber W, Lardon J, Gees F, Brügger L, Ott T (2015) Repeated controlled rockfall trajectory testing. [Abstract] Geophys. Res. Abstr. 17: EGU2015-9779. [2] Volkwein A, Klette J (2014) Semi-Automatic Determination of Rockfall Trajectories. Sensors 14: 18187-18210.

Increased vascularization during early healing after biologic augmentation in repair of chronic rotator cuff tears using autologous leukocyte- and platelet-rich fibrin (L-PRF): a prospective randomized controlled pilot trial.

PubMed

Zumstein, Matthias A; Rumian, Adam; Lesbats, Virginie; Schaer, Michael; Boileau, Pascal

2014-01-01

We hypothesized that arthroscopic rotator cuff repairs using leukocyte- and platelet-rich fibrin (L-PRF) in a standardized, modified protocol is technically feasible and results in a higher vascularization response and watertight healing rate during early healing. Twenty patients with chronic rotator cuff tears were randomly assigned to 2 treatment groups. In the test group (N = 10), L-PRF was added in between the tendon and the bone during arthroscopic rotator cuff repair. The second group served as control (N = 10). They received the same arthroscopic treatment without the use of L-PRF. We used a double-row tension band technique. Clinical examinations including subjective shoulder value, visual analog scale, Constant, and Simple Shoulder Test scores and measurement of the vascularization with power Doppler ultrasonography were made at 6 and 12 weeks. There have been no postoperative complications. At 6 and 12 weeks, there was no significant difference in the clinical scores between the test and the control groups. The mean vascularization index of the surgical tendon-to-bone insertions was always significantly higher in the L-PRF group than in the contralateral healthy shoulders at 6 and 12 weeks (P = .0001). Whereas the L-PRF group showed a higher vascularization compared with the control group at 6 weeks (P = .001), there was no difference after 12 weeks of follow-up (P = .889). Watertight healing was obtained in 89% of the repaired cuffs. Arthroscopic rotator cuff repair with the application of L-PRF is technically feasible and yields higher early vascularization. Increased vascularization may potentially predispose to an increased and earlier cellular response and an increased healing rate. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

A rapid quantification of binocular misalignment without recording eye movements: Vertical and torsional alignment nulling.

PubMed

Beaton, Kara H; Shelhamer, Mark J; Roberts, Dale C; Schubert, Michael C

2017-05-01

Small, innate asymmetries between the left and right otolith organs can cause ocular misalignment with symptoms that include double vision and motion sickness. Additionally, ocular misalignment affects nearly 5% of the US population. We have developed a portable, non-invasive technology that uses subjective perception of binocular visual signals to estimate relative binocular alignment. The Vertical Alignment Nulling (VAN) and Torsional Alignment Nulling (TAN) tests ask subjects to view one red and one blue line on a tablet computer while looking through color-matched red and blue filters so that each eye sees only one of the lines. Subjects align the red and blue lines, which are initially vertically offset from one another during VAN or rotated relative to one another during TAN, until they perceive a single continuous line. Ocular misalignments are inferred from actual offsets in the final line positions. During testing, all binocular visual cues are eliminated by employing active-matrix organic light-emitting diode (AMOLED) technology and testing in darkness. VAN and TAN can accurately account for visual offsets induced by prisms, and test-retest reliability is excellent, with resolution better than many current standard clinical tests. VAN and TAN tests are similar to the clinical Lancaster red-green test. However, VAN and TAN employ inexpensive, hand-held hardware that can be self-administered with results that are quickly quantifiable. VAN and TAN provide simple, sensitive, and quantitative measures of binocular positioning alignment that may be useful for detecting subtle abnormalities in ocular positioning. Copyright © 2017 Elsevier B.V. All rights reserved.

Physiologic adaptation of man in space; Proceedings of the Seventh International Man in Space Symposium, Houston, TX, Feb. 10-13, 1986

NASA Technical Reports Server (NTRS)

Holland, Albert W. (Editor)

1987-01-01

Topics discussed in this volume include space motion sickness, cardiovascular adaptation, fluid shifts, extravehicular activity, general physiology, perception, vestibular response modifications, vestibular physiology, and pharmacology. Papers are presented on the clinical characterization and etiology of space motion sickness, ultrasound techniques in space medicine, fluid shifts in weightlessness, Space Shuttle inflight and postflight fluid shifts measured by leg volume changes, and the probability of oxygen toxicity in an 8-psi space suit. Consideration is also given to the metabolic and hormonal status of crewmembers in short-term space flights, adaptive changes in perception of body orientation and mental image rotation in microgravity, the effects of a visual-vestibular stimulus on the vestibulo-ocular reflex, rotation tests in the weightless phase of parabolic flight, and the mechanisms of antimotion sickness drugs.

Intuitive parameter-free visualization of tumor vascularization using rotating connectivity projections

NASA Astrophysics Data System (ADS)

Wiemker, Rafael; Bülow, Thomas; Opfer, Roland; Kabus, Sven; Dharaiya, Ekta

2008-03-01

We present an effective and intuitive visualization of the macro-vasculature of a selected nodule or tumor in three-dimensional image data (e.g. CT, MR, US). For the differential diagnosis of nodules the possible distortion of adjacent vessels is one important clinical criterion. Surface renderings of vessel- and tumor-segmentations depend critically on the chosen parameter- and threshold-values for the underlying segmentation. Therefore we use rotating Maximum Intensity Projections (MIPs) of a volume of interests (VOI) around the selected tumor. The MIP does not require specific parameters, and allows much quicker visual inspection in comparison to slicewise navigation, while the rotation gives depth cues to the viewer. Of the vessel network within the VOI, however, not all vessels are connected to the selected tumor, and it is tedious to sort out which adjacent vessels are in fact connected and which are overlaid only by projection. Therefore we suggest a simple transformation of the original image values into connectivity values. In the derived connectedness-image each voxel value corresponds to the lowest image value encountered on the highest possible pathway from the tumor to the voxel. The advantage of the visualization is that no implicit binary decision is made whether a certain vessel is connected to the tumor or not, but rather the degree of connectedness is visualized as the brightness of the vessel. Non-connected structures disappear, feebly connected structures appear faint, and strongly connected structures remain in their original brightness. The visualization does not depend on delicate threshold values. Promising results have been achieved for pulmonary nodules in CT.

Combined CT-based and image-free navigation systems in TKA reduces postoperative outliers of rotational alignment of the tibial component.

PubMed

Mitsuhashi, Shota; Akamatsu, Yasushi; Kobayashi, Hideo; Kusayama, Yoshihiro; Kumagai, Ken; Saito, Tomoyuki

2018-02-01

Rotational malpositioning of the tibial component can lead to poor functional outcome in TKA. Although various surgical techniques have been proposed, precise rotational placement of the tibial component was difficult to accomplish even with the use of a navigation system. The purpose of this study is to assess whether combined CT-based and image-free navigation systems replicate accurately the rotational alignment of tibial component that was preoperatively planned on CT, compared with the conventional method. We compared the number of outliers for rotational alignment of the tibial component using combined CT-based and image-free navigation systems (navigated group) with those of conventional method (conventional group). Seventy-two TKAs were performed between May 2012 and December 2014. In the navigated group, the anteroposterior axis was prepared using CT-based navigation system and the tibial component was positioned under control of the navigation. In the conventional group, the tibial component was placed with reference to the Akagi line that was determined visually. Fisher's exact probability test was performed to evaluate the results. There was a significant difference between the two groups with regard to the number of outliers: 3 outliers in the navigated group compared with 12 outliers in the conventional group (P < 0.01). We concluded that combined CT-based and image-free navigation systems decreased the number of rotational outliers of tibial component, and was helpful for the replication of the accurate rotational alignment of the tibial component that was preoperatively planned.

Ultrasound and Functional Assessment of Transtendinous Repairs of Partial-Thickness Articular-Sided Rotator Cuff Tears.

PubMed

Ostrander, Roger V; Klauser, Jeffrey M; Menon, Sanjay; Hackel, Joshua G

2017-03-01

Partial-thickness articular-sided rotator cuff tears are a frequent source of shoulder pain. Despite conservative measures, some patients continue to be symptomatic and require surgical management. However, there is some controversy as to which surgical approach results in the best outcomes for grade 3 tears. The purpose of this study was to evaluate repair integrity and the clinical results of patients treated with transtendinous repair of high-grade partial-thickness articular-sided rotator cuff tears. Our hypothesis was that transtendinous repairs would result in reliable healing and acceptable functional outcomes. Case series; Level of evidence, 4. Twenty patients with a minimum follow-up of 2 years were included in the study. All patients underwent arthroscopic repair of high-grade partial-thickness rotator cuff tears utilizing a transtendinous technique by a single surgeon. At latest follow-up, the repair integrity was evaluated using ultrasound imaging, and functional scores were calculated. Ultrasound evaluation demonstrated that 18 of 20 patients had complete healing with a normal-appearing rotator cuff. Two patients had a minor residual partial tear. Sixteen of 20 patients had no pain on visual analog scale. Four patients complained of mild intermittent residual pain. All patients were rated as "excellent" by both the University of California at Los Angeles Shoulder Score and the Simple Shoulder Test. The transtendon technique for the repair of articular-sided high-grade partial rotator cuff tears results in reliable tendon healing and excellent functional outcomes.

A laboratory study of mean flow generation in rotating fluids by Reynolds stress gradients

NASA Astrophysics Data System (ADS)

McGuinness, D. S.; Boyer, D. L.; Fernando, H. J. S.

2001-06-01

Laboratory experiments were conducted that demonstrate that a mean azimuthal flow can be produced by introducing Reynolds stress gradients to a rotating fluid with zero initial mean flow. This mechanism may play a role in the generation of mean currents in coastal regions. The experiments entail the establishment of turbulence in a thin annular-shaped region centered within a cylindrical test cell through the use of a vertically oscillating grid. This region rests in a horizontal plane perpendicular to the vertical axis of the tank, and the entire system is placed on a turntable to simulate background rotation. Flow visualization techniques are used to depict qualitative features of the resulting flow field. Measurements of the mean and turbulent velocity fields are performed using a two-component laser-Doppler velocimeter. The results show how rectified currents (mean flows) can be generated via Reynolds stress gradients induced by periodic forcing of the grid. In the absence of background rotation, rectified flow is observed in the radial and vertical directions only. The presence of background rotation tends to organize these motions in that the flow tends to move parallel to the turbulent source, i.e., in the azimuthal direction, with the source (strong turbulence) located to the right, facing downstream. The influence of rotation on the Reynolds stresses and their gradients as well as on the ensuing mean flow is evaluated, and the observations are examined by considering individual contributions of the terms in the Reynolds-averaged momentum equations.

Generalization of vestibular learning to earth-fixed targets is possible but limited when the polarity of afferent vestibular information is changed.

PubMed

Mackrous, I; Simoneau, M

2014-02-28

To maintain perception of the world around us during body motion, the brain must update the spatial presentation of visual stimuli, known as space updating. Previous studies have demonstrated that vestibular signals contribute to space updating. Nonetheless, when being passively rotated in the dark, the ability to keep track of a memorized earth-fixed target (EFT) involves learning mechanism(s). We tested whether such learning generalizes across different EFT eccentricities. Furthermore, we ascertained whether learning transfers to similar target eccentricities but in the opposite direction. Participants were trained to predict the position of an EFT (located at 45° to their left) while being rotated counterclockwise (i.e., they press a push button when they perceived that their body midline have cross the position of the target). Overall, the results indicated that learning transferred to other target eccentricity (30° and 60°) for identical body rotation direction. In contrast, vestibular learning partly transferred to target location's matching body rotation but in the opposite rotation direction. Generalization of learning implies that participants do not adopt cognitive strategies to improve their performance during training. We argue that the brain learned to use vestibular signals for space updating. Generalization of learning while being rotated in the opposite direction implies that some parts of the neural networks involved in space updating is shared between trained and untrained direction. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Visual- and Vestibular-Autonomic Influence on Short-Term Cardiovascular Regulatory Mechanisms

NASA Technical Reports Server (NTRS)

Mullen, Thomas J.; Ramsdell, Craig D.

1999-01-01

This synergy project was a one-year effort conducted cooperatively by members of the NSBRI Cardiovascular Alterations and Neurovestibular Adaptation Teams in collaboration with NASA Johnson Space Center (JSC) colleagues. The objective of this study was to evaluate visual autonomic interactions on short-term cardiovascular regulatory mechanisms. Based on established visual-vestibular and vestibular-autonomic shared neural pathways, we hypothesized that visually induced changes in orientation will trigger autonomic cardiovascular reflexes. A second objective was to compare baroreflex changes during postural changes as measured with the new Cardiovascular System Identification (CSI) technique with those measured using a neck barocuff. While the neck barocuff stimulates only the carotid baroreceptors, CSI provides a measure of overall baroreflex responsiveness. This study involved a repeated measures design with 16 healthy human subjects (8 M, 8 F) to examine cardiovascular regulatory responses during actual and virtual head-upright tilts. Baroreflex sensitivity was first evaluated with subjects in supine and upright positions during actual tilt-table testing using both neck barocuff and CSI methods. The responses to actual tilts during this first session were then compared to responses during visually induced tilt and/or rotation obtained during a second session.

Web-based Interactive Simulator for Rotating Machinery.

ERIC Educational Resources Information Center

Sirohi, Vijayalaxmi

1999-01-01

Baroma (Balance of Rotating Machinery), the Web-based educational engineering interactive software for teaching/learning combines didactical and software ergonomical approaches. The software in tutorial form simulates a problem using Visual Interactive Simulation in graphic display, and animation is brought about through graphical user interface…

Experimental analysis and flow visualization of a thin liquid film on a stationary and rotating disk

NASA Technical Reports Server (NTRS)

Thomas, S.; Faghri, A.; Hankey, W.

1991-01-01

The mean thickness of a thin liquid film of deionized water with a free surface on a stationary and rotating horizontal disk has been measured with a nonobtrusive capacitance technique. The measurements were taken when the rotational speed ranged from 0-300 rpm and the flow rate varied from 7.0-15.0 lpm. A flow visualization study of the thin film was also performed to determine the characteristics of the waves on the free surface. When the disk was stationary, a circular hydraulic jump was present on the disk. Upstream from the jump, the film thickness was determined by the inertial and frictional forces on the fluid, and the radial spreading of the film. The surface tension at the edge of the disk affected the film thickness downstream from the jump. For the rotating disk, the film thickness was dependent upon the inertial and frictional forces near the center of the disk and the centrifugal forces near the edge of the disk.

Learning Rotation-Invariant Local Binary Descriptor.

PubMed

Duan, Yueqi; Lu, Jiwen; Feng, Jianjiang; Zhou, Jie

2017-08-01

In this paper, we propose a rotation-invariant local binary descriptor (RI-LBD) learning method for visual recognition. Compared with hand-crafted local binary descriptors, such as local binary pattern and its variants, which require strong prior knowledge, local binary feature learning methods are more efficient and data-adaptive. Unlike existing learning-based local binary descriptors, such as compact binary face descriptor and simultaneous local binary feature learning and encoding, which are susceptible to rotations, our RI-LBD first categorizes each local patch into a rotational binary pattern (RBP), and then jointly learns the orientation for each pattern and the projection matrix to obtain RI-LBDs. As all the rotation variants of a patch belong to the same RBP, they are rotated into the same orientation and projected into the same binary descriptor. Then, we construct a codebook by a clustering method on the learned binary codes, and obtain a histogram feature for each image as the final representation. In order to exploit higher order statistical information, we extend our RI-LBD to the triple rotation-invariant co-occurrence local binary descriptor (TRICo-LBD) learning method, which learns a triple co-occurrence binary code for each local patch. Extensive experimental results on four different visual recognition tasks, including image patch matching, texture classification, face recognition, and scene classification, show that our RI-LBD and TRICo-LBD outperform most existing local descriptors.

Effects of hand orientation on motor imagery--event related potentials suggest kinesthetic motor imagery to solve the hand laterality judgment task.

PubMed

Jongsma, Marijtje L A; Meulenbroek, Ruud G J; Okely, Judith; Baas, C Marjolein; van der Lubbe, Rob H J; Steenbergen, Bert

2013-01-01

Motor imagery (MI) refers to the process of imagining the execution of a specific motor action without actually producing an overt movement. Two forms of MI have been distinguished: visual MI and kinesthetic MI. To distinguish between these forms of MI we employed an event related potential (ERP) study to measure interference effects induced by hand orientation manipulations in a hand laterality judgement task. We hypothesized that this manipulation should only affect kinesthetic MI but not visual MI. The ERPs elicited by rotated hand stimuli contained the classic rotation related negativity (RRN) with respect to palm view stimuli. We observed that laterally rotated stimuli led to a more marked RRN than medially rotated stimuli. This RRN effect was observed when participants had their hands positioned in either a straight (control) or an inward rotated posture, but not when their hands were positioned in an outward rotated posture. Posture effects on the ERP-RRN have not previously been studied. Apparently, a congruent hand posture (hands positioned in an outward rotated fashion) facilitates the judgement of the otherwise more demanding laterally rotated hand stimuli. These ERP findings support a kinesthetic interpretation of MI involved in solving the hand laterality judgement task. The RRN may be used as a non-invasive marker for kinesthetic MI and seems useful in revealing the covert behavior of MI in e.g. rehabilitation programs.

Automated visual inspection system based on HAVNET architecture

NASA Astrophysics Data System (ADS)

Burkett, K.; Ozbayoglu, Murat A.; Dagli, Cihan H.

1994-10-01

In this study, the HAusdorff-Voronoi NETwork (HAVNET) developed at the UMR Smart Engineering Systems Lab is tested in the recognition of mounted circuit components commonly used in printed circuit board assembly systems. The automated visual inspection system used consists of a CCD camera, a neural network based image processing software and a data acquisition card connected to a PC. The experiments are run in the Smart Engineering Systems Lab in the Engineering Management Dept. of the University of Missouri-Rolla. The performance analysis shows that the vision system is capable of recognizing different components under uncontrolled lighting conditions without being effected by rotation or scale differences. The results obtained are promising and the system can be used in real manufacturing environments. Currently the system is being customized for a specific manufacturing application.

Temporal dynamics of ocular position dependence of the initial human vestibulo-ocular reflex.

PubMed

Crane, Benjamin T; Tian, Junru; Demer, Joseph L

2006-04-01

While an ideal vestibulo-ocular reflex (VOR) generates ocular rotations compensatory for head motion, during visually guided movements, Listing's Law (LL) constrains the eye to rotational axes lying in Listing's Plane (LP). The present study was conducted to explore the recent proposal that the VOR's rotational axis is not collinear with the head's, but rather follows a time-dependent strategy intermediate between LL and an ideal VOR. Binocular LPs were defined during visual fixation in eight normal humans. The VOR was evoked by a highly repeatable transient whole-body yaw rotation in darkness at a peak acceleration of 2800 deg/s2. Immediately before rotation, subjects regarded targets 15 or 500 cm distant located at eye level, 20 degrees up, or 20 degrees down. Eye and head responses were compared with LL predictions in the position and velocity domains. LP orientation varied both among subjects and between individual subject's eyes, and rotated temporally with convergence by 5 +/- 5 degrees (+/-SEM). In the position domain, the eye compensated for head displacement even when the head rotated out of LP. Even within the first 20 ms from onset of head rotation, the ocular velocity axis tilted relative to the head axis by 30% +/- 8% of vertical gaze position. Saccades increased this tilt. Regardless of vertical gaze position, the ocular rotation axis tilted backward 4 degrees farther in abduction than in adduction. There was also a binocular vertical eye velocity transient and lateral tilt of the ocular axis. These disconjugate, short-latency axis perturbations appear intrinsic to the VOR and may have neural or mechanical origins.

SU-F-T-61: Treatment Planning Observations for the CivaSheet Directional Brachytherapy Device Using VariSeed 9.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rivard, MJ; Rothley, DJ

2016-06-15

Purpose: The VariSeed 9.0 brachytherapy TPS is recently available and has new features such as ability to rotate a brachytherapy source away from normal to the imaging plane. Consequently, a dosimetric analysis was performed for a directional brachytherapy source (CivaSheet) with tests of this functionality and experiences from clinical treatment planning were documented. These observations contribute to safe, practical, and accurate use of such new software features. Methods: Several tests were established to evaluate the new rotational feature, specific to the CivaSheet for the first patients treated using this new brachytherapy device. These included suitability of imaging slice-thickness and in-planemore » resolution, window/level adjustments for brachytherapy source visualization, commissioning the source physical length for performing rotations, and using different planar and 3D window views to identify source orientation. Additional CivaSheet-specific tests were performed to determine the dosimetric influence on target coverage: changing the source tilt angle, source positioning in the treatment plan based on the CivaSheet rectangular array of CivaDots, and influence of prescription depth on the necessary treatment margin for adequate target coverage. Results: Higher imaging-resolution produced better accuracy for source orientation and positioning, with sub-millimeter CT slice-thickness and in-plane resolution preferred. Source rotation was possible only in sagittal or coronal views. The process for validating source orientation required iteratively altering rotations then checking them in the 3D view, which was cumbersome given the absence of quantitative plan documentation to indicate orientation. Given the small Pd-103 source size, influence of source tilt within 30° was negligible for <1.0 cm. Influence of source position was important when the source was positioned in/out of the adjacent source plane, causing changes of 15%, 7%, and 3% at depths of 0.5, 0.7, and 1.0 cm. Conclusion: The new TPS rotational feature worked well, but several issues were identified to improve the treatment planning process. Research supported in part by CivaTech Oncology, Inc. for Dr. Rivard.« less

Development of Three Versions of a Wheelchair Ergometer for Curvilinear Manual Wheelchair Propulsion Using Virtual Reality.

PubMed

Salimi, Zohreh; Ferguson-Pell, Martin

2018-06-01

Although wheelchair ergometers provide a safe and controlled environment for studying or training wheelchair users, until recently they had a major disadvantage in only being capable of simulating straight-line wheelchair propulsion. Virtual reality has helped overcome this problem and broaden the usability of wheelchair ergometers. However, for a wheelchair ergometer to be validly used in research studies, it needs to be able to simulate the biomechanics of real world wheelchair propulsion. In this paper, three versions of a wheelchair simulator were developed. They provide a sophisticated wheelchair ergometer in an immersive virtual reality environment. They are intended for manual wheelchair propulsion and all are able to simulate simple translational inertia. In addition, each of the systems reported uses a different approach to simulate wheelchair rotation and accommodate rotational inertial effects. The first system does not provide extra resistance against rotation and relies on merely linear inertia, hypothesizing that it can provide acceptable replication of biomechanics of wheelchair maneuvers. The second and third systems, however, are designed to simulate rotational inertia. System II uses mechanical compensation, and System III uses visual compensation simulating the influence that rotational inertia has on the visual perception of wheelchair movement in response to rotation at different speeds.

Exploratory study of the relations between spatial ability and drawing from memory.

PubMed

Czarnolewski, Mark Y; Eliot, John

2012-04-01

Test scores of 119 students, attending either a public four-year college or a technical school, were related to their proportionality and detail drawing scores on the Memory for Designs Test. In regression models, the ETS Maze Tracing, Eliot-Price Mental Rotations, and Bender-Gestalt tests were consistent predictors of proportionality scores, with the latter two tests uniquely related to these. The ETS Shapes Memory Test and the Form Board Test were the strongest predictors for detail accuracy scores. The Shapes test predicted proportionality when the CTY Visual Memory Test BB was excluded. The models then provided support for the hypothesis that drawing designs from memory, a critical skill in drawing, regardless of whether one focuses on accuracy for proportionality scores or for detail scores, is jointly related to the measures of recognition, production, and traditional spatial ability measures. This study identified multifaceted skills in drawing from memory.

Digital implementation of a neural network for imaging

NASA Astrophysics Data System (ADS)

Wood, Richard; McGlashan, Alex; Yatulis, Jay; Mascher, Peter; Bruce, Ian

2012-10-01

This paper outlines the design and testing of a digital imaging system that utilizes an artificial neural network with unsupervised and supervised learning to convert streaming input (real time) image space into parameter space. The primary objective of this work is to investigate the effectiveness of using a neural network to significantly reduce the information density of streaming images so that objects can be readily identified by a limited set of primary parameters and act as an enhanced human machine interface (HMI). Many applications are envisioned including use in biomedical imaging, anomaly detection and as an assistive device for the visually impaired. A digital circuit was designed and tested using a Field Programmable Gate Array (FPGA) and an off the shelf digital camera. Our results indicate that the networks can be readily trained when subject to limited sets of objects such as the alphabet. We can also separate limited object sets with rotational and positional invariance. The results also show that limited visual fields form with only local connectivity.

The effects of computer-aided design software on engineering students' spatial visualisation skills

NASA Astrophysics Data System (ADS)

Kösa, Temel; Karakuş, Fatih

2018-03-01

The purpose of this study was to determine the influence of computer-aided design (CAD) software-based instruction on the spatial visualisation skills of freshman engineering students in a computer-aided engineering drawing course. A quasi-experimental design was applied, using the Purdue Spatial Visualization Test-Visualization of Rotations (PSVT:R) for both the pre- and the post-test. The participants were 116 freshman students in the first year of their undergraduate programme in the Department of Mechanical Engineering at a university in Turkey. A total of 72 students comprised the experimental group; they were instructed with CAD-based activities in an engineering drawing course. The control group consisted of 44 students who did not attend this course. The results of the study showed that a CAD-based engineering drawing course had a positive effect on developing engineering students' spatial visualisation skills. Additionally, the results of the study showed that spatial visualisation skills can be a predictor for success in a computer-aided engineering drawing course.

The Axial Curve Rotator.

ERIC Educational Resources Information Center

Hunter, Walter M.

This document contains detailed directions for constructing a device that mechanically produces the three-dimensional shape resulting from the rotation of any algebraic line or curve around either axis on the coordinate plant. The device was developed in response to student difficulty in visualizing, and thus grasping the mathematical principles…

Effects of a compression garment on shoulder external rotation force outputs during isotonic contractions.

PubMed

Tsuruike, Masaaki; Ellenbecker, Todd S

2013-02-01

The use of compression garments (CGs) has been advocated for performance enhancement and recovery in athletes. The effect of a CG on humeral rotation motor control has not been previously tested. The purpose of this study was to examine the isotonic contraction of external rotation (ER) of the glenohumeral joint at different force outputs to determine the effect of wearing a long sleeve CG on muscular performance. Twelve male college tennis players and 12 male college soccer players were tested for ER of the dominant shoulder during both concentric and eccentric isotonic contractions. The subjects performed 5 consecutive repetitions of both concentric and eccentric ER at 20-30% and 40-50% of maximum voluntary isometric contraction (MVIC) intensities. All subjects were tested with and without CG as well as with and without ongoing visual feedback information (OVFI). The order of CG wearing and the presence of OVFI were randomly assigned across all subjects. The results indicated a significant 3-way interaction between CG wearing and OVFI across 2 loads. Specifically, significantly different mean value of the completion time was found between OVFI and no-OVFI without CG wearing at 40-50% of MVIC, whereas no difference in the completion time was found with and without OVFI with CG wearing. Taken together, with CG wearing, athletes may have ER at 40-50% of MVIC more readily maintained by peripheral feedback without visuomotor control imposed on force outputs as compared without CG wearing.

Forced convection in vertical Bridgman configuration with the submerged heater

NASA Astrophysics Data System (ADS)

Meyer, S.; Ostrogorsky, A. G.

1997-02-01

Ga-doped Ge single crystals were grown in vertical Bridgman configuration, using the submerged heater method (SHM). When used without rotation, the submerged heater drastically reduces convection at the solid-liquid interface. When the submerged heater is set in to rotation or oscillatory rotation, it acts as a centrifugal viscous pump, inducing forced convection (radial-inward flow) along the interface. The flow produced by a rotation and oscillatory rotation of the submerged heater was visualized using a 1 : 1 scale model. The vigorous mixing produced by the oscillatory rotation creates a nearly perfectly stirred melt, and yields a uniform lateral distribution of the dopant. The crystals were free of unintentionally produced striae.

Influence of Near-Segment Positioning in a Rotationally Asymmetric Multifocal Intraocular Lens.

PubMed

Song, In Seok; Yoon, Sam Young; Kim, Jae Yong; Kim, Myoung Joon; Tchah, Hungwon

2016-04-01

To compare visual performance and higher order aberrations (HOAs) based on the position of the near segment in eyes with rotationally asymmetric multifocal intraocular lenses (IOLs). Asymmetric multifocal IOLs (Lentis Mplus LS-313; Oculentis Optikgeräte GmbH, Wetzlar, Germany) were implanted with the near segment positioned either inferiorly, superiorly, or temporally. Uncorrected distance (UDVA), intermediate (UIVA), and near (UNVA) visual acuity, corrected distance visual acuity (CDVA), and distance-corrected intermediate (DCIVA) and near (DCNVA) visual acuity, contrast sensitivity, HOAs, and subjective symptom questionnaires were compared at 1 month postoperatively. Forty-five eyes from 45 patients were evaluated (n = 25, 9, and 11 eyes in the inferior, superior, and temporal groups, respectively). No significant differences in UDVA, UIVA, UNVA, CDVA, DCIVA, or DCNVA were found between the three groups (P > .05). The temporal group showed the best results in UDVA, CDVA, and DCNVA, but the inferior group showed the best results in DCIVA and UNVA and the superior group showed the best results in UIVA. Contrast sensitivity and the subjective symptom questionnaire also did not demonstrate any significant differences (P > .05). Total HOA and spherical aberration did not demonstrate any statistically significant differences (P > .05), but vertical coma and horizontal coma demonstrated significant differences based on near segment position (P < .001). The position of the near segment in eyes with rotationally asymmetric multifocal IOLs demonstrates no significant effect on visual performance. Copyright 2016, SLACK Incorporated.

Visual and non-visual control of landing movements in humans

PubMed Central

Santello, Marco; McDonagh, Martin J N; Challis, John H

2001-01-01

The role of vision in controlling leg muscle activation in landing from a drop was investigated. Subjects (n = 8) performed 10 drops from four heights (0.2, 0.4, 0.6 and 0.8 m) with and without vision. Drop height was maintained constant throughout each block of trials to allow adaptation. The aim of the study was to assess the extent to which proprioceptive and vestibular information could substitute for the lack of vision in adapting landing movements to different heights. At the final stages of the movement, subjects experienced similar peak centre of body mass (CM) displacements and joint rotations, regardless of the availability of vision. This implies that subjects were able to adapt the control of landing to different heights. The amplitude and timing of electromyographic signals from the leg muscles scaled to drop height in a similar fashion with and without vision. However, variables measured throughout the execution of the movement indicated important differences. Without vision, landings were characterised by 10 % larger ground reaction forces, 10 % smaller knee joint rotations, different time lags between peak joint rotations, and more variable ground reaction forces and times to peak CM displacement. We conclude that non-visual sensory information (a) could not fully compensate for the lack of continuous visual feedback and (b) this non-visual information was used to reorganise the motor output. These results suggest that vision is important for the very accurate timing of muscle activity onset and the kinematics of landing. PMID:11711583

SU-E-T-234: Daily Quality Assurance for a Six Degrees of Freedom Couch Using a Novel Phantom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woods, K; Woollard, J; Ayan, A

2015-06-15

Purpose: To test the accuracy and reproducibility of both translational and rotational movements for a couch with six degrees of freedom (6DoF) using a novel phantom design Methods: An end-to-end test was carried out using two different phantoms. A 6 cm3 cube with a central fiducial BB (WL-QA Sun Nuclear) and a custom fabricated rectangular prism (31 cm x 8 cm x 8 cm), placed on a baseplate with known angular offsets for pitch, roll and yaw with a central fiducial BB and unique surface structures for registration purposes, were used. The end-to-end test included an initial CT simulation formore » a reference study, setup to an offset mark on each phantom, registration of the reference CT to the acquired cone-beam CT, and final Winston-Lutz delivery at four cardinal gantry angles. Results for both translational and rotational movements were recorded and compared for both phantoms. Results: Translational and rotational measurements were performed with a PerfectPitch (Varian) couch for 10 trials for both phantoms. Distinct translational shifts were [−5.372±0.384mm, −10.183±0.137mm, 14.028±0.155mm] for the cube and [7.520±0.159mm, −9.117±0.101mm, 16.273±0.115mm] for the prototype phantom for lateral, longitudinal, and vertical shifts, respectively. Distinct rotational adjustments were [1.121±0.102o, −1.067±0.235o, −2.662±0.380o] for the cube and [2.534±0.059o, 1.994±0.025o, 2.094±0.076o] for the prototype for pitch, roll, and yaw, respectively. Winston-Lutz test results performed after 6DoF couch correction from each cardinal gantry angle ranged from 0.26–0.72mm for the cube and 0.55–0.86mm for the prototype. Conclusion: The prototype phantom is more precise for both translational and rotational adjustments compared to a commercial phantom. The design of the prototype phantom allows for a more discernible visual confirmation of correct translational and rotational adjustments with the prototype phantom. Winston-Lutz results are more accurate for the commercial phantom but are still within tolerance for the prototype phantom.« less

Tracking single particle rotation: Probing dynamics in four dimensions

DOE PAGES

Anthony, Stephen Michael; Yu, Yan

2015-04-29

Direct visualization and tracking of small particles at high spatial and temporal resolution provides a powerful approach to probing complex dynamics and interactions in chemical and biological processes. Analysis of the rotational dynamics of particles adds a new dimension of information that is otherwise impossible to obtain with conventional 3-D particle tracking. In this review, we survey recent advances in single-particle rotational tracking, with highlights on the rotational tracking of optically anisotropic Janus particles. Furthermore, strengths and weaknesses of the various particle tracking methods, and their applications are discussed.

On the barn owl's visual pre-attack behavior: I. Structure of head movements and motion patterns.

PubMed

Ohayon, Shay; van der Willigen, Robert F; Wagner, Hermann; Katsman, Igor; Rivlin, Ehud

2006-09-01

Barn owls exhibit a rich repertoire of head movements before taking off for prey capture. These movements occur mainly at light levels that allow for the visual detection of prey. To investigate these movements and their functional relevance, we filmed the pre-attack behavior of barn owls. Off-line image analysis enabled reconstruction of all six degrees of freedom of head movements. Three categories of head movements were observed: fixations, head translations and head rotations. The observed rotations contained a translational component. Head rotations did not follow Listing's law, but could be well described by a second-order surface, which indicated that they are in close agreement with Donder's law. Head translations did not contain any significant rotational components. Translations were further segmented into straight-line and curved paths. Translations along an axis perpendicular to the line of sight were similar to peering movements observed in other animals. We suggest that these basic motion elements (fixations, head rotations, translations along a straight line, and translation along a curved trajectory) may be combined to form longer and more complex behavior. We speculate that these head movements mainly underlie estimation of distance during prey capture.

Correlations among visual analogue scale, neck disability index, shoulder joint range of motion, and muscle strength in young women with forward head posture.

PubMed

Shin, Young Jun; Kim, Won Hyo; Kim, Seong Gil

2017-08-01

This study investigated the correlation between the neck disability index (NDI) and visual analogue scale (VAS), which are indicators of neck pain, shoulder joint range of motion (ROM), and muscle strength in women with a slight forward head posture. This study was carried out on 42 female college students attending Uiduk University in Gyeongju, Korea. The neck pain and disability index for each subject was measured using VAS and NDI, respectively. Two physiotherapists measured the shoulder joint ROM and muscle strengths of the subjects using a goniometer and a dynamometer, respectively. External rotation, internal rotation, and abduction of the shoulder joint were measured for each subject. A significant negative correlation between neck pain and shoulder joint ROM in external rotation and the muscle strength of the shoulder joint in abduction was found in the subjects. In addition, a significant positive correlation was observed between ROM in external rotation and muscle strength in abduction. This study showed a significant negative correlation between neck pain and ROM in external rotation as well as between neck pain and the muscle strength in abduction.

A Balanced Comparison of Object Invariances in Monkey IT Neurons.

PubMed

Ratan Murty, N Apurva; Arun, Sripati P

2017-01-01

Our ability to recognize objects across variations in size, position, or rotation is based on invariant object representations in higher visual cortex. However, we know little about how these invariances are related. Are some invariances harder than others? Do some invariances arise faster than others? These comparisons can be made only upon equating image changes across transformations. Here, we targeted invariant neural representations in the monkey inferotemporal (IT) cortex using object images with balanced changes in size, position, and rotation. Across the recorded population, IT neurons generalized across size and position both stronger and faster than to rotations in the image plane as well as in depth. We obtained a similar ordering of invariances in deep neural networks but not in low-level visual representations. Thus, invariant neural representations dynamically evolve in a temporal order reflective of their underlying computational complexity.

Rotational imaging optical coherence tomography for full-body mouse embryonic imaging

PubMed Central

Wu, Chen; Sudheendran, Narendran; Singh, Manmohan; Larina, Irina V.; Dickinson, Mary E.; Larin, Kirill V.

2016-01-01

Abstract. Optical coherence tomography (OCT) has been widely used to study mammalian embryonic development with the advantages of high spatial and temporal resolutions and without the need for any contrast enhancement probes. However, the limited imaging depth of traditional OCT might prohibit visualization of the full embryonic body. To overcome this limitation, we have developed a new methodology to enhance the imaging range of OCT in embryonic day (E) 9.5 and 10.5 mouse embryos using rotational imaging. Rotational imaging OCT (RI-OCT) enables full-body imaging of mouse embryos by performing multiangle imaging. A series of postprocessing procedures was performed on each cross-section image, resulting in the final composited image. The results demonstrate that RI-OCT is able to improve the visualization of internal mouse embryo structures as compared to conventional OCT. PMID:26848543

Differential color brightness as a body orientation cue

NASA Technical Reports Server (NTRS)

Barbour, Christopher G.; Coss, Richard G.

1988-01-01

Ninety male and female college students reclining on their backs in the dark were disoriented when positioned on a rotating platform under a slowly rotating disk that filled their entire visual field. Half of the disk was painted with a brighter value (about 69 percent higher luminance level) of the color on the other half. The effects of red, blue, and yellow were examined. Subjects wearing frosted goggles viewed the illuminated disk for three rotations. The disk was stopped when the subjects felt that they were right side up. A significant proportion of subjects selected the disk position in which the brighter side of each of the three colors filled their upper visual field. These results suggest that color brightness as well as lighting variation could provide Space Station crew members with body orientation cues as they move around.

Anisotropic Rotational Diffusion Studied by Nuclear Spin Relaxation and Molecular Dynamics Simulation: An Undergraduate Physical Chemistry Laboratory

ERIC Educational Resources Information Center

Fuson, Michael M.

2017-01-01

Laboratories studying the anisotropic rotational diffusion of bromobenzene using nuclear spin relaxation and molecular dynamics simulations are described. For many undergraduates, visualizing molecular motion is challenging. Undergraduates rarely encounter laboratories that directly assess molecular motion, and so the concept remains an…

Microgravity

NASA Image and Video Library

2002-08-07

Brad McLain for the Space Biology Museum Network spins a volunteer in a rotating chair to illustrate how dependent the human vestibular system is on visual cues. The volunteer's thumbs indicate which way she thinks she is turning. Similar tests are conducted on astronauts to study how they adapt to space and readapt to Earth. The activity was part of the Space Research and You education event held by NASA's Office of Biological and Physical Research on June 25, 2002, in Arlington, VA, to highlight the research that will be conducted on STS-107.

A causal role for V5/MT neurons coding motion-disparity conjunctions in resolving perceptual ambiguity.

PubMed

Krug, Kristine; Cicmil, Nela; Parker, Andrew J; Cumming, Bruce G

2013-08-05

Judgments about the perceptual appearance of visual objects require the combination of multiple parameters, like location, direction, color, speed, and depth. Our understanding of perceptual judgments has been greatly informed by studies of ambiguous figures, which take on different appearances depending upon the brain state of the observer. Here we probe the neural mechanisms hypothesized as responsible for judging the apparent direction of rotation of ambiguous structure from motion (SFM) stimuli. Resolving the rotation direction of SFM cylinders requires the conjoint decoding of direction of motion and binocular depth signals [1, 2]. Within cortical visual area V5/MT of two macaque monkeys, we applied electrical stimulation at sites with consistent multiunit tuning to combinations of binocular depth and direction of motion, while the monkey made perceptual decisions about the rotation of SFM stimuli. For both ambiguous and unambiguous SFM figures, rotation judgments shifted as if we had added a specific conjunction of disparity and motion signals to the stimulus elements. This is the first causal demonstration that the activity of neurons in V5/MT contributes directly to the perception of SFM stimuli and by implication to decoding the specific conjunction of disparity and motion, the two different visual cues whose combination drives the perceptual judgment. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Principles and biophysical applications of single particle super-localization and rotational tracking

NASA Astrophysics Data System (ADS)

Gu, Yan

While conventional Single Particle Tracking (SPT) techniques acquire 2D or 3D trajectories of particle probes, we have developed Single Particle Orientation and Rotational Tracking (SPORT) techniques to extract orientation and rotational information. Combined with DIC microscopy, the SPORT technique has been applied in biophysical studies, including membrane diffusion and intracellular transport. The rotational dynamics of nanoparticle vectors on live cell membranes was recorded and its influence on the fate of these nanoparticle vectors was elucidated. The rotational motions of gold nanorods with various surface modifiers were tracked continuously at a temporal resolution of 5 ms under a DIC microscope. We found that the rotational behaviors of gold nanorod vectors are strongly related to their surface charge, specific surface functional groups, and the availability of receptors on cell membranes. The study of rotational Brownian motion of nanoparticles on cell membranes will lead to a better understanding of the mechanisms of drug delivery and provide guidance in designing surface modification strategies for drug delivery vectors under various circumstances. To characterize the rotation mode of surface functionalized gold nanorods on cell membranes, the SPORT technique is combined with the correlation analysis of the bright and dark DIC intensities. The unique capabilities of visualizing and understanding rotational motions of functionalized nanoparticles on live cell membranes allow us to correlate rotational and translational dynamics in unprecedented detail and provide new insights for complex membrane processes, including electrostatic interactions, ligand-receptor binding, and lateral (confined and hopping) diffusion of membrane receptors. Surface-functionalized nanoparticles interact with the membrane in fundamentally different ways and exhibit distinct rotational modes. The early events of particle-membrane approach and attachment are directly visualized for the first time. The rotational dynamics of cargos in both active directional transport and pausing stages of axonal transport was also visualized using high-speed SPORT with a temporal resolution of 2 ms. Both long and short pauses are imaged, and the correlations between the pause duration, the rotational behaviour of the cargo at the pause, and the moving direction after the pause are established. Furthermore, the rotational dynamics leading to switching tracks are visualized in detail. These first-time observations of cargo's rotational dynamics provide new insights on how kinesin and dynein motors take the cargo through the alternating stages of active directional transport and pause. To improve the localization precision of the SPT technique with DIC microscopy, a precise three-dimensional (3D) localization method of spherical gold nanoparticle probes using model-based correlation coefficient mapping was introduced. To accomplish this, a stack of sample images at different z-positions are acquired, and a 3D intensity profile of the probe serving as the model is used to map out the positions of nanoparticles in the sample. By using this model-based correlation imaging method, precise localization can be achieved in imaging techniques with complicated point spread functions (PSF) such as differential interference contrast (DIC) microscopy. The 3D superlocalization method was applied to tracking gold nanospheres during live endocytosis events. Finally, a novel dual-modality imaging technique has been developed to super-localize a single gold nanorod while providing its orientation and rotational information. The super-localization of the gold nanorod can be accomplished by curve fitting the modified bright-field images generated by one of the two beams laterally shifted by the first Nomarski prism in a DIC microscope. The orientation and rotational information is derived from the DIC images of gold nanorods. The new imaging setup has been applied to study the steric hindrance induced by relatively large cargos in the microtubule gliding assay and to track nanocargos in the crowded cellular environment.

Principles and biophysical applications of single particle super-localization and rotational tracking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gu, Yan

While conventional Single Particle Tracking (SPT) techniques acquire 2D or 3D trajectories of particle probes, we have developed Single Particle Orientation and Rotational Tracking (SPORT) techniques to extract orientation and rotational information. Combined with DIC microscopy, the SPORT technique has been applied in biophysical studies, including membrane diffusion and intracellular transport. The rotational dynamics of nanoparticle vectors on live cell membranes was recorded and its influence on the fate of these nanoparticle vectors was elucidated. The rotational motions of gold nanorods with various surface modifiers were tracked continuously at a temporal resolution of 5 ms under a DIC microscope. Wemore » found that the rotational behaviors of gold nanorod vectors are strongly related to their surface charge, specific surface functional groups, and the availability of receptors on cell membranes. The study of rotational Brownian motion of nanoparticles on cell membranes will lead to a better understanding of the mechanisms of drug delivery and provide guidance in designing surface modification strategies for drug delivery vectors under various circumstances. To characterize the rotation mode of surface functionalized gold nanorods on cell membranes, the SPORT technique is combined with the correlation analysis of the bright and dark DIC intensities. The unique capabilities of visualizing and understanding rotational motions of functionalized nanoparticles on live cell membranes allow us to correlate rotational and translational dynamics in unprecedented detail and provide new insights for complex membrane processes, including electrostatic interactions, ligand-receptor binding, and lateral (confined and hopping) diffusion of membrane receptors. Surface-functionalized nanoparticles interact with the membrane in fundamentally different ways and exhibit distinct rotational modes. The early events of particle-membrane approach and attachment are directly visualized for the first time. The rotational dynamics of cargos in both active directional transport and pausing stages of axonal transport was also visualized using high-speed SPORT with a temporal resolution of 2 ms. Both long and short pauses are imaged, and the correlations between the pause duration, the rotational behaviour of the cargo at the pause, and the moving direction after the pause are established. Furthermore, the rotational dynamics leading to switching tracks are visualized in detail. These first-time observations of cargo's rotational dynamics provide new insights on how kinesin and dynein motors take the cargo through the alternating stages of active directional transport and pause. To improve the localization precision of the SPT technique with DIC microscopy, a precise three-dimensional (3D) localization method of spherical gold nanoparticle probes using model-based correlation coefficient mapping was introduced. To accomplish this, a stack of sample images at different z-positions are acquired, and a 3D intensity profile of the probe serving as the model is used to map out the positions of nanoparticles in the sample. By using this model-based correlation imaging method, precise localization can be achieved in imaging techniques with complicated point spread functions (PSF) such as differential interference contrast (DIC) microscopy. The 3D superlocalization method was applied to tracking gold nanospheres during live endocytosis events. Finally, a novel dual-modality imaging technique has been developed to super-localize a single gold nanorod while providing its orientation and rotational information. The super-localization of the gold nanorod can be accomplished by curve fitting the modified bright-field images generated by one of the two beams laterally shifted by the first Nomarski prism in a DIC microscope. The orientation and rotational information is derived from the DIC images of gold nanorods. The new imaging setup has been applied to study the steric hindrance induced by relatively large cargos in the microtubule gliding assay and to track nanocargos in the crowded cellular environment.« less

Computer-aided light sheet flow visualization using photogrammetry

NASA Technical Reports Server (NTRS)

Stacy, Kathryn; Severance, Kurt; Childers, Brooks A.

1994-01-01

A computer-aided flow visualization process has been developed to analyze video images acquired from rotating and translating light sheet visualization systems. The computer process integrates a mathematical model for image reconstruction, advanced computer graphics concepts, and digital image processing to provide a quantitative and a visual analysis capability. The image reconstruction model, based on photogrammetry, uses knowledge of the camera and light sheet locations and orientations to project two-dimensional light sheet video images into three-dimensional space. A sophisticated computer visualization package, commonly used to analyze computational fluid dynamics (CFD) results, was chosen to interactively display the reconstructed light sheet images with the numerical surface geometry for the model or aircraft under study. The photogrammetric reconstruction technique and the image processing and computer graphics techniques and equipment are described. Results of the computer-aided process applied to both a wind tunnel translating light sheet experiment and an in-flight rotating light sheet experiment are presented. The capability to compare reconstructed experimental light sheet images with CFD solutions in the same graphics environment is also demonstrated.

Computer-Aided Light Sheet Flow Visualization

NASA Technical Reports Server (NTRS)

Stacy, Kathryn; Severance, Kurt; Childers, Brooks A.

1993-01-01

A computer-aided flow visualization process has been developed to analyze video images acquired from rotating and translating light sheet visualization systems. The computer process integrates a mathematical model for image reconstruction, advanced computer graphics concepts, and digital image processing to provide a quantitative and visual analysis capability. The image reconstruction model, based on photogrammetry, uses knowledge of the camera and light sheet locations and orientations to project two-dimensional light sheet video images into three-dimensional space. A sophisticated computer visualization package, commonly used to analyze computational fluid dynamics (CFD) data sets, was chosen to interactively display the reconstructed light sheet images, along with the numerical surface geometry for the model or aircraft under study. A description is provided of the photogrammetric reconstruction technique, and the image processing and computer graphics techniques and equipment. Results of the computer aided process applied to both a wind tunnel translating light sheet experiment and an in-flight rotating light sheet experiment are presented. The capability to compare reconstructed experimental light sheet images and CFD solutions in the same graphics environment is also demonstrated.

Computer-aided light sheet flow visualization

NASA Technical Reports Server (NTRS)

Stacy, Kathryn; Severance, Kurt; Childers, Brooks A.

1993-01-01

A computer-aided flow visualization process has been developed to analyze video images acquired from rotating and translating light sheet visualization systems. The computer process integrates a mathematical model for image reconstruction, advanced computer graphics concepts, and digital image processing to provide a quantitative and visual analysis capability. The image reconstruction model, based on photogrammetry, uses knowledge of the camera and light sheet locations and orientations to project two-dimensional light sheet video images into three-dimensional space. A sophisticated computer visualization package, commonly used to analyze computational fluid dynamics (CFD) data sets, was chosen to interactively display the reconstructed light sheet images, along with the numerical surface geometry for the model or aircraft under study. A description is provided of the photogrammetric reconstruction technique, and the image processing and computer graphics techniques and equipment. Results of the computer aided process applied to both a wind tunnel translating light sheet experiment and an in-flight rotating light sheet experiment are presented. The capability to compare reconstructed experimental light sheet images and CFD solutions in the same graphics environment is also demonstrated.

Performance and Near-Wake Flow field of A Marine Hydrokinetic Turbine Operating in Free surface Proximity

NASA Astrophysics Data System (ADS)

Banerjee, Arindam; Kolekar, Nitin

2015-11-01

The current experimental investigation aims at understanding the effect of free surface proximity and associated blockage on near-wake flow-field and performance of a three bladed horizontal axis marine hydrokinetic turbine. Experiments were conducted on a 0.14m radius, three bladed constant chord turbine in a 0.61m ×0.61m test section water channel. The turbine was subjected to various rotational speeds, flow speeds and depths of immersion. Experimental data was acquired through a submerged in-line thrust-torque sensor that was corrected to an unblocked dataset with a blockage correction using measured thrust data. A detailed comparison is presented between blocked and unblocked datasets to identify influence of Reynolds number and free surface proximity on blockage effects. The percent change in Cp was found to be dependent on flow velocity, rotational speed and free surface to blade tip clearance. Further, flow visualization using a stereoscopic particle image velocimetry was carried out in the near-wake region of turbine to understand the mechanism responsible for variation of Cp with rotational speed and free surface proximity. Results revealed presence of slower wake at higher rotational velocities and increased asymmetry in the wake at high free surface proximity.

Effectiveness of Platelet-rich Plasma Injection for Rotator Cuff Tendinopathy: A Prospective Open-label Study.

PubMed

Scarpone, Michael; Rabago, David; Snell, Edward; Demeo, Patrick; Ruppert, Kristine; Pritchard, Perry; Arbogast, Gennie; Wilson, John J; Balzano, John F

2013-03-01

Assess platelet rich plasma (PRP) injection for rotator cuff tendinopathy (RCT). Prospective open label study with 1-year follow-up. Participants recruited from an outpatient sports medicine clinic had clinically and magnetic resonance image (MRI)-demonstrated RCT refractory to physical therapy and corticosteroid injection. They received one ultrasound-guided injection of 3.0 mL of 1% xylocaine followed by 3.5 mL of PRP at the lesion and surrounding tendon. 0-10 visual analog scale (VAS; baseline, 8, 12, and 52 weeks). functional shoulder tests assessing rotator cuff strength and endurance (at baseline and 8 and 12 weeks), MRI severity (1-5 points [at baseline and 4 and 8 weeks]), and patient satisfaction (52 weeks). Eighteen participants with 19 assessed shoulders reported VAS pain score improvement from 7.5 ± 0.3 points to 0.5 ± 0.3 points by week 12 and 0.4 ± 0.2 (P = .0001) points at week 52. Functional outcomes significantly improved; the largest effect was seen in the external rotation test: 33.5 ± 5.7 seconds to 62.6 ± 7.2 seconds at week 12 (P = .0001). MRI appearance improved by 1 to 3 points in 16 of 18 assessed shoulders. Seventeen participants were "completely satisfied" (12) or "satisfied" (5). One participant was "unsatisfied." A single ultrasound-guided, intralesional injection of PRP resulted in safe, significant, sustained improvement of pain, function, and MRI outcomes in participants with refractory RCT. Randomized multidisciplinary effectiveness trials that add ultrasound and validated clinical outcome measures are needed to further assess PRP for RCT.

Effects of acupuncture and placebo TENS in addition to exercise in treatment of rotator cuff tendinitis.

PubMed

Razavi, Mahnaz; Jansen, Gunilla Brodda

2004-12-01

To compare the effect of acupuncture with placebo transcutaneous electrical nerve stimulation (TENS) when added to the exercise treatment of rotator cuff tendinitis with respect to pain, shoulder movements and function. Prospective alternate allocation controlled trial. Outpatient department. Thirty-three patients (12 women and 21 men) were included in the study. All had clinically diagnosed rotator cuff tendinitis. Both groups underwent a standardized training programme. Each patient received in addition either 10 treatments with acupuncture or placebo TENS, 1-2 times per week. The parameters investigated were intensity of pain (measured with visual analogue scale), active, passive as well as functional movements in the shoulder (hand in neck (HIN) and pour out of a pot (POP)). Patients were tested before treatment, after treatment and at a six-month follow-up. Medicine intake, ability to lie on the affected side and sleep disturbances were evaluated. A subjective assessment was made after the treatment and at follow-up. Sixteen patients had acupuncture, 17 placebo TENS. Eight patients endured pain at rest in the placebo TENS group, and 10 in the acupuncture group. After treatment both groups improved, the improvement persisted at the six-month follow-up. Both groups increased range of movement. Except for the functional test HIN in the acupuncture group, there were no differences between the groups regarding other parameters investigated directly after treatment or at six-month follow-up. There is no difference between the effect of additional acupuncture treatment and placebo TENS in the treatment of rotator cuff tendinitis.

Vision-based real-time position control of a semi-automated system for robot-assisted joint fracture surgery.

PubMed

Dagnino, Giulio; Georgilas, Ioannis; Tarassoli, Payam; Atkins, Roger; Dogramadzi, Sanja

2016-03-01

Joint fracture surgery quality can be improved by robotic system with high-accuracy and high-repeatability fracture fragment manipulation. A new real-time vision-based system for fragment manipulation during robot-assisted fracture surgery was developed and tested. The control strategy was accomplished by merging fast open-loop control with vision-based control. This two-phase process is designed to eliminate the open-loop positioning errors by closing the control loop using visual feedback provided by an optical tracking system. Evaluation of the control system accuracy was performed using robot positioning trials, and fracture reduction accuracy was tested in trials on ex vivo porcine model. The system resulted in high fracture reduction reliability with a reduction accuracy of 0.09 mm (translations) and of [Formula: see text] (rotations), maximum observed errors in the order of 0.12 mm (translations) and of [Formula: see text] (rotations), and a reduction repeatability of 0.02 mm and [Formula: see text]. The proposed vision-based system was shown to be effective and suitable for real joint fracture surgical procedures, contributing a potential improvement of their quality.

Ionospheric Specifications for SAR Interferometry (ISSI)

NASA Technical Reports Server (NTRS)

Pi, Xiaoqing; Chapman, Bruce D; Freeman, Anthony; Szeliga, Walter; Buckley, Sean M.; Rosen, Paul A.; Lavalle, Marco

2013-01-01

The ISSI software package is designed to image the ionosphere from space by calibrating and processing polarimetric synthetic aperture radar (PolSAR) data collected from low Earth orbit satellites. Signals transmitted and received by a PolSAR are subject to the Faraday rotation effect as they traverse the magnetized ionosphere. The ISSI algorithms combine the horizontally and vertically polarized (with respect to the radar system) SAR signals to estimate Faraday rotation and ionospheric total electron content (TEC) with spatial resolutions of sub-kilometers to kilometers, and to derive radar system calibration parameters. The ISSI software package has been designed and developed to integrate the algorithms, process PolSAR data, and image as well as visualize the ionospheric measurements. A number of tests have been conducted using ISSI with PolSAR data collected from various latitude regions using the phase array-type L-band synthetic aperture radar (PALSAR) onboard Japan Aerospace Exploration Agency's Advanced Land Observing Satellite mission, and also with Global Positioning System data. These tests have demonstrated and validated SAR-derived ionospheric images and data correction algorithms.

The Influence of 16-year-old Students' Gender, Mental Abilities, and Motivation on their Reading and Drawing Submicrorepresentations Achievements

NASA Astrophysics Data System (ADS)

Devetak, Iztok; Aleksij Glažar, Saša

2010-08-01

Submicrorepresentations (SMRs) are a powerful tool for identifying misconceptions of chemical concepts and for generating proper mental models of chemical phenomena in students' long-term memory during chemical education. The main purpose of the study was to determine which independent variables (gender, formal reasoning abilities, visualization abilities, and intrinsic motivation for learning chemistry) have the maximum influence on students' reading and drawing SMRs. A total of 386 secondary school students (aged 16.3 years) participated in the study. The instruments used in the study were: test of Chemical Knowledge, Test of Logical Thinking, two tests of visualization abilities Patterns and Rotations, and questionnaire on Intrinsic Motivation for Learning Science. The results show moderate, but statistically significant correlations between students' intrinsic motivation, formal reasoning abilities and chemical knowledge at submicroscopic level based on reading and drawing SMRs. Visualization abilities are not statistically significantly correlated with students' success on items that comprise reading or drawing SMRs. It can be also concluded that there is a statistically significant difference between male and female students in solving problems that include reading or drawing SMRs. Based on these statistical results and content analysis of the sample problems, several educational strategies can be implemented for students to develop adequate mental models of chemical concepts on all three levels of representations.

Gravitoinertial force background level affects adaptation to coriolis force perturbations of reaching movements

NASA Technical Reports Server (NTRS)

Lackner, J. R.; Dizio, P.

1998-01-01

We evaluated the combined effects on reaching movements of the transient, movement-dependent Coriolis forces and the static centrifugal forces generated in a rotating environment. Specifically, we assessed the effects of comparable Coriolis force perturbations in different static force backgrounds. Two groups of subjects made reaching movements toward a just-extinguished visual target before rotation began, during 10 rpm counterclockwise rotation, and after rotation ceased. One group was seated on the axis of rotation, the other 2.23 m away. The resultant of gravity and centrifugal force on the hand was 1.0 g for the on-center group during 10 rpm rotation, and 1.031 g for the off-center group because of the 0.25 g centrifugal force present. For both groups, rightward Coriolis forces, approximately 0.2 g peak, were generated during voluntary arm movements. The endpoints and paths of the initial per-rotation movements were deviated rightward for both groups by comparable amounts. Within 10 subsequent reaches, the on-center group regained baseline accuracy and straight-line paths; however, even after 40 movements the off-center group had not resumed baseline endpoint accuracy. Mirror-image aftereffects occurred when rotation stopped. These findings demonstrate that manual control is disrupted by transient Coriolis force perturbations and that adaptation can occur even in the absence of visual feedback. An increase, even a small one, in background force level above normal gravity does not affect the size of the reaching errors induced by Coriolis forces nor does it affect the rate of reacquiring straight reaching paths; however, it does hinder restoration of reaching accuracy.

Helicopter flight simulation motion platform requirements

NASA Astrophysics Data System (ADS)

Schroeder, Jeffery Allyn

Flight simulators attempt to reproduce in-flight pilot-vehicle behavior on the ground. This reproduction is challenging for helicopter simulators, as the pilot is often inextricably dependent on external cues for pilot-vehicle stabilization. One important simulator cue is platform motion; however, its required fidelity is unknown. To determine the required motion fidelity, several unique experiments were performed. A large displacement motion platform was used that allowed pilots to fly tasks with matched motion and visual cues. Then, the platform motion was modified to give cues varying from full motion to no motion. Several key results were found. First, lateral and vertical translational platform cues had significant effects on fidelity. Their presence improved performance and reduced pilot workload. Second, yaw and roll rotational platform cues were not as important as the translational platform cues. In particular, the yaw rotational motion platform cue did not appear at all useful in improving performance or reducing workload. Third, when the lateral translational platform cue was combined with visual yaw rotational cues, pilots believed the platform was rotating when it was not. Thus, simulator systems can be made more efficient by proper combination of platform and visual cues. Fourth, motion fidelity specifications were revised that now provide simulator users with a better prediction of motion fidelity based upon the frequency responses of their motion control laws. Fifth, vertical platform motion affected pilot estimates of steady-state altitude during altitude repositionings. This refutes the view that pilots estimate altitude and altitude rate in simulation solely from visual cues. Finally, the combined results led to a general method for configuring helicopter motion systems and for developing simulator tasks that more likely represent actual flight. The overall results can serve as a guide to future simulator designers and to today's operators.

Temporal Dynamics of Ocular Position Dependence of the Initial Human Vestibulo-ocular Reflex

PubMed Central

Crane, Benjamin T.; Tian, Junru; Demer, Joseph L.

2007-01-01

Purpose While an ideal vestibulo-ocular reflex (VOR) generates ocular rotations compensatory for head motion, during visually guided movements, Listing’s Law (LL) constrains the eye to rotational axes lying in Listing’s Plane (LP). The present study was conducted to explore the recent proposal that the VOR’s rotational axis is not collinear with the head’s, but rather follows a time-dependent strategy intermediate between LL and an ideal VOR. Methods Binocular LPs were defined during visual fixation in eight normal humans. The VOR was evoked by a highly repeatable transient whole-body yaw rotation in darkness at a peak acceleration of 2800 deg/s2. Immediately before rotation, subjects regarded targets 15 or 500 cm distant located at eye level, 20° up, or 20° down. Eye and head responses were compared with LL predictions in the position and velocity domains. Results LP orientation varied both among subjects and between individual subject’s eyes, and rotated temporally with convergence by 5 ± 5° (±SEM). In the position domain, the eye compensated for head displacement even when the head rotated out of LP. Even within the first 20 ms from onset of head rotation, the ocular velocity axis tilted relative to the head axis by 30% ± 8% of vertical gaze position. Saccades increased this tilt. Regardless of vertical gaze position, the ocular rotation axis tilted backward 4° farther in abduction than in adduction. There was also a binocular vertical eye velocity transient and lateral tilt of the ocular axis. Conclusions These disconjugate, short-latency axis perturbations appear intrinsic to the VOR and may have neural or mechanical origins. PMID:16565376

The nature of Trojan asteroid 624 Hektor

NASA Technical Reports Server (NTRS)

Hartmann, W. K.; Cruikshank, D. P.

1978-01-01

Near-simultaneous visual and thermal IR (20-micron) photometry of the Trojan asteroid 624 Hektor is reported which was performed when the asteroid was observed nearly along its rotation axis. The results confirm and refine the low albedo and large size of this asteroid and confirm the general rotational-pole position and aspect angle predicted by Dunlap and Gehrels (1969). Hektor is found to be a truly extraordinary object in that it is larger and far more irregular in shape than other measured Trojans and far more irregular than other belt asteroids of comparable size. It is proposed that Hektor could be a partially coalesced pair of Trojan asteroids which collided with energy too low to cause complete fragmentation, thus forming a dumbbell-shaped object. A possible scenario is outlined according to which the two pre-Hektor objects were neighboring relatively large primitive spheroidal planetesimals trapped in Jupiter's Lagrangian cloud. Observational and theoretical tests of this model are suggested.

Shoulder internal rotation elbow flexion test for diagnosing cubital tunnel syndrome.

PubMed

Ochi, Kensuke; Horiuchi, Yukio; Tanabe, Aya; Waseda, Makoto; Kaneko, Yasuhito; Koyanagi, Takahiro

2012-06-01

Shoulder internal rotation enhances symptom provocation attributed to cubital tunnel syndrome. We present a modified elbow flexion test--the shoulder internal rotation elbow flexion test--for diagnosing cubital tunnel syndrome. Fifty-five ulnar nerves in cubital tunnel syndrome patients and 123 ulnar nerves in controls were examined with 5 seconds each of elbow flexion, shoulder internal rotation, and shoulder internal rotation elbow flexion tests before and after treatment (surgery in 18; conservative in others). For the shoulder internal rotation elbow flexion test position, 90° abduction, maximum internal rotation, and 10° flexion of the shoulder were combined with the elbow flexion test position. The test was considered positive if any symptom for cubital tunnel syndrome developed <5 seconds. Influence of the shoulder internal rotation elbow flexion test was evaluated by nerve conduction studies in 10 cubital tunnel syndrome nerves and 7 control nerves. The sensitivities/specificities of the 5-second elbow flexion, shoulder internal rotation, and shoulder internal rotation elbow flexion tests were 25%/100%, 58%/100%, and 87%/98%, respectively. Sensitivity differences between the shoulder internal rotation elbow flexion test and the other two tests were significant. Shoulder internal rotation elbow flexion test results and cubital tunnel syndrome symptoms were significantly correlated. Influence of the shoulder internal rotation elbow flexion test on the ulnar nerve was seen in 8 of 10 cubital tunnel syndrome nerves but not in controls. The 5-second shoulder internal rotation elbow flexion test is specific, easy and quick provocative test for diagnosing cubital tunnel syndrome. Copyright © 2012 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

The influence of visual and vestibular orientation cues in a clock reading task.

PubMed

Davidenko, Nicolas; Cheong, Yeram; Waterman, Amanda; Smith, Jacob; Anderson, Barrett; Harmon, Sarah

2018-05-23

We investigated how performance in the real-life perceptual task of analog clock reading is influenced by the clock's orientation with respect to egocentric, gravitational, and visual-environmental reference frames. In Experiment 1, we designed a simple clock-reading task and found that observers' reaction time to correctly tell the time depends systematically on the clock's orientation. In Experiment 2, we dissociated egocentric from environmental reference frames by having participants sit upright or lie sideways while performing the task. We found that both reference frames substantially contribute to response times in this task. In Experiment 3, we placed upright or rotated participants in an upright or rotated immersive virtual environment, which allowed us to further dissociate vestibular from visual cues to the environmental reference frame. We found evidence of environmental reference frame effects only when visual and vestibular cues were aligned. We discuss the implications for the design of remote and head-mounted displays. Copyright © 2018 Elsevier Inc. All rights reserved.

Choice reaction time to movement of eccentric visual targets during concurrent rotary acceleration

NASA Technical Reports Server (NTRS)

Hamerman, J. A.

1979-01-01

This study investigates the influence of concurrent rotary acceleration on choice reaction time (RT) to a small, accelerating visual cursor on a cathode-ray tube. Subjects sat in an enclosed rotating device at the center of rotation and observed a 3-mm dot accelerating at different rates across a cathode-ray tube. The dot was viewed at various eccentricities under conditions of visual stimulation alone and with concurrent rotary acceleration. Subjects responded to both vertical and horizontal dot movements. There was a significant inverse relationship between choice RT and level of dot acceleration (p less than .001), and a significant direct relationship between choice RT and eccentricity (p less than .001). There was no significant difference between choice RT to vertical or horizontal dot motion (p greater than .25), and choice RT was not significantly affected by concurrent rotary acceleration (p greater than .10). The results are discussed in terms of the effects of vestibular stimulation on choice RT to visual motion.

Role of somatosensory and vestibular cues in attenuating visually induced human postural sway

NASA Technical Reports Server (NTRS)

Peterka, Robert J.; Benolken, Martha S.

1993-01-01

The purpose was to determine the contribution of visual, vestibular, and somatosensory cues to the maintenance of stance in humans. Postural sway was induced by full field, sinusoidal visual surround rotations about an axis at the level of the ankle joints. The influences of vestibular and somatosensory cues were characterized by comparing postural sway in normal and bilateral vestibular absent subjects in conditions that provided either accurate or inaccurate somatosensory orientation information. In normal subjects, the amplitude of visually induced sway reached a saturation level as stimulus amplitude increased. The saturation amplitude decreased with increasing stimulus frequency. No saturation phenomena was observed in subjects with vestibular loss, implying that vestibular cues were responsible for the saturation phenomenon. For visually induced sways below the saturation level, the stimulus-response curves for both normal and vestibular loss subjects were nearly identical implying that (1) normal subjects were not using vestibular information to attenuate their visually induced sway, possibly because sway was below a vestibular-related threshold level, and (2) vestibular loss subjects did not utilize visual cues to a greater extent than normal subjects; that is, a fundamental change in visual system 'gain' was not used to compensate for a vestibular deficit. An unexpected finding was that the amplitude of body sway induced by visual surround motion could be almost three times greater than the amplitude of the visual stimulus in normals and vestibular loss subjects. This occurred in conditions where somatosensory cues were inaccurate and at low stimulus amplitudes. A control system model of visually induced postural sway was developed to explain this finding. For both subject groups, the amplitude of visually induced sway was smaller by a factor of about four in tests where somatosensory cues provided accurate versus inaccurate orientation information. This implied that (1) the vestibular loss subjects did not utilize somatosensory cues to a greater extent than normal subjects; that is, changes in somatosensory system 'gain' were not used to compensate for a vestibular deficit, and (2) the threshold for the use of vestibular cues in normals was apparently lower in test conditions where somatosensory cues were providing accurate orientation information.

Relation between Approximate Number System Acuity and Mathematical Achievement: The Influence of Fluency

PubMed Central

Wang, Li; Sun, Yuhua; Zhou, Xinlin

2016-01-01

Previous studies have observed inconsistent relations between the acuity of the Approximate Number System (ANS) and mathematical achievement. In this paper, we hypothesize that the relation between ANS acuity and mathematical achievement is influenced by fluency; that is, the mathematical achievement test covering a greater expanse of mathematical fluency may better reflect the relation between ANS acuity and mathematics skills. We explored three types of mathematical achievement tests utilized in this study: Subtraction, graded, and semester-final examination. The subtraction test was designed to measure the mathematical fluency. The graded test was more fluency-based than the semester-final examination, but both involved the same mathematical knowledge from the class curriculum. A total of 219 fifth graders from primary schools were asked to perform all three tests, then given a numerosity comparison task, a visual form perception task (figure matching), and a series of other tasks to assess general cognitive processes (mental rotation, non-verbal matrix reasoning, and choice reaction time). The findings were consistent with our expectations. The relation between ANS acuity and mathematical achievement was particularly clearly reflected in the participants’ performance on the visual form perception task, which supports the domain-general explanations for the underlying mechanisms of the relation between ANS acuity and math achievement. PMID:28066291

Asymmetric vestibular stimulation reveals persistent disruption of motion perception in unilateral vestibular lesions.

PubMed

Panichi, R; Faralli, M; Bruni, R; Kiriakarely, A; Occhigrossi, C; Ferraresi, A; Bronstein, A M; Pettorossi, V E

2017-11-01

Self-motion perception was studied in patients with unilateral vestibular lesions (UVL) due to acute vestibular neuritis at 1 wk and 4, 8, and 12 mo after the acute episode. We assessed vestibularly mediated self-motion perception by measuring the error in reproducing the position of a remembered visual target at the end of four cycles of asymmetric whole-body rotation. The oscillatory stimulus consists of a slow (0.09 Hz) and a fast (0.38 Hz) half cycle. A large error was present in UVL patients when the slow half cycle was delivered toward the lesion side, but minimal toward the healthy side. This asymmetry diminished over time, but it remained abnormally large at 12 mo. In contrast, vestibulo-ocular reflex responses showed a large direction-dependent error only initially, then they normalized. Normalization also occurred for conventional reflex vestibular measures (caloric tests, subjective visual vertical, and head shaking nystagmus) and for perceptual function during symmetric rotation. Vestibular-related handicap, measured with the Dizziness Handicap Inventory (DHI) at 12 mo correlated with self-motion perception asymmetry but not with abnormalities in vestibulo-ocular function. We conclude that 1 ) a persistent self-motion perceptual bias is revealed by asymmetric rotation in UVLs despite vestibulo-ocular function becoming symmetric over time, 2 ) this dissociation is caused by differential perceptual-reflex adaptation to high- and low-frequency rotations when these are combined as with our asymmetric stimulus, 3 ) the findings imply differential central compensation for vestibuloperceptual and vestibulo-ocular reflex functions, and 4 ) self-motion perception disruption may mediate long-term vestibular-related handicap in UVL patients. NEW & NOTEWORTHY A novel vestibular stimulus, combining asymmetric slow and fast sinusoidal half cycles, revealed persistent vestibuloperceptual dysfunction in unilateral vestibular lesion (UVL) patients. The compensation of motion perception after UVL was slower than that of vestibulo-ocular reflex. Perceptual but not vestibulo-ocular reflex deficits correlated with dizziness-related handicap. Copyright © 2017 the American Physiological Society.

Design of an Image Fusion Phantom for a Small Animal microPET/CT Scanner Prototype

NASA Astrophysics Data System (ADS)

Nava-García, Dante; Alva-Sánchez, Héctor; Murrieta-Rodríguez, Tirso; Martínez-Dávalos, Arnulfo; Rodríguez-Villafuerte, Mercedes

2010-12-01

Two separate microtomography systems recently developed at Instituto de Física, UNAM, produce anatomical (microCT) and physiological images (microPET) of small animals. In this work, the development and initial tests of an image fusion method based on fiducial markers for image registration between the two modalities are presented. A modular Helix/Line-Sources phantom was designed and constructed; this phantom contains fiducial markers that can be visualized in both imaging systems. The registration was carried out by solving the rigid body alignment problem of Procrustes to obtain rotation and translation matrices required to align the two sets of images. The microCT/microPET image fusion of the Helix/Line-Sources phantom shows excellent visual coincidence between different structures, showing a calculated target-registration-error of 0.32 mm.

Establishing a New Screening System for Mild Cognitive Impairment and Alzheimer's Disease with Mental Rotation Tasks that Evaluate Visuospatial Function.

PubMed

Suzuki, Ayuko; Shinozaki, Jun; Yazawa, Shogo; Ueki, Yoshino; Matsukawa, Noriyuki; Shimohama, Shun; Nagamine, Takashi

2018-01-01

The mental rotation task is well-known for the assessment of visuospatial function; however, it has not been used for screening of dementia patients. The aim of this study was to create a simple screening test for patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) by focusing on non-amnestic symptoms. Age-matched healthy controls (age 75.3±6.8), patients with MCI (76.5±5.5), and AD (78.2±5.0) participated in this study. They carried out mental rotation tasks targeting geometric graphics or alphabetical characters with three rotating angles (0°, 90°, and 180°) and indicated the correct answer. Response accuracy and reaction time were recorded along with their eye movements using an eye tracker. To quantify their visual processing strategy, the run count ratio (RC ratio) was calculated by dividing the mean number of fixations in incorrect answers by that in correct answers. AD patients showed lower accuracy and longer reaction time than controls. They also showed a significantly greater number of fixation and smaller saccade amplitude than controls, while fixation duration did not differ significantly. The RC ratio was higher for AD, followed by MCI and control groups. By setting the cut-off value to 0.47 in the 180° rotating angle task, we could differentiate MCI patients from controls with a probability of 80.0%. We established a new screening system for dementia patients by evaluating visuospatial function. The RC ratio during a mental rotation task is useful for discriminating MCI patients from controls.

Rotational wind indicator enhances control of rotated displays

NASA Technical Reports Server (NTRS)

Cunningham, H. A.; Pavel, Misha

1991-01-01

Rotation by 108 deg of the spatial mapping between a visual display and a manual input device produces large spatial errors in a discrete aiming task. These errors are not easily corrected by voluntary mental effort, but the central nervous system does adapt gradually to the new mapping. Bernotat (1970) showed that adding true hand position to a 90 deg rotated display improved performance of a compensatory tracking task, but tracking error rose again upon removal of the explicit cue. This suggests that the explicit error signal did not induce changes in the neural mapping, but rather allowed the operator to reduce tracking error using a higher mental strategy. In this report, we describe an explicit visual display enhancement applied to a 108 deg rotated discrete aiming task. A 'wind indicator' corresponding to the effect of the mapping rotation is displayed on the operator-controlled cursor. The human operator is instructed to oppose the virtual force represented by the indicator, as one would do if flying an airplane in a crosswind. This enhancement reduces spatial aiming error in the first 10 minutes of practice by an average of 70 percent when compared to a no enhancement control condition. Moreover, it produces adaptation aftereffect, which is evidence of learning by neural adaptation rather than by mental strategy. Finally, aiming error does not rise upon removal of the explicit cue.

Gender differences in brain activation on a mental rotation task.

PubMed

Semrud-Clikeman, Margaret; Fine, Jodene Goldenring; Bledsoe, Jesse; Zhu, David C

2012-10-01

Few neuroimaging studies have explored gender differences on mental rotation tasks. Most studies have utilized samples with both genders, samples mainly consisting of men, or samples with six or fewer females. Graduate students in science fields or liberal arts programs (20 males, 20 females) completed a mental rotation task during functional magnetic resonance imaging (fMRI). When a pair of cube figures was shown, the participant made a keypad response based on whether the pair is the same/similar or different. Regardless of gender, the bilateral middle frontal gyrus, bilateral intraparietal sulcus (IPS), and the left precuneus were activated when a subject tried to solve the mental rotation task. Increased activation in the right inferior frontal gyrus/middle frontal gyrus, the left precuneus/posterior cingulate cortex/cuneus region, and the left middle occipital gyrus was found for men as compared to women. Better accuracy and shorter response times were correlated with an increased activation in the bilateral intraparietal sulcus. No significant brain activity differences related to mental rotation were found between academic majors. These findings suggest that networks involved in visual attention appear to be more strongly activated in the mental rotation tasks in men as compared to women. It also suggests that men use a more automatic process when analyzing complex visual reasoning tasks while women use a more top-down process.

Visual processing of rotary motion.

PubMed

Werkhoven, P; Koenderink, J J

1991-01-01

Local descriptions of velocity fields (e.g., rotation, divergence, and deformation) contain a wealth of information for form perception and ego motion. In spite of this, human psychophysical performance in estimating these entities has not yet been thoroughly examined. In this paper, we report on the visual discrimination of rotary motion. A sequence of image frames is used to elicit an apparent rotation of an annulus, composed of dots in the frontoparallel plane, around a fixation spot at the center of the annulus. Differential angular velocity thresholds are measured as a function of the angular velocity, the diameter of the annulus, the number of dots, the display time per frame, and the number of frames. The results show a U-shaped dependence of angular velocity discrimination on spatial scale, with minimal Weber fractions of 7%. Experiments with a scatter in the distance of the individual dots to the center of rotation demonstrate that angular velocity cannot be assessed directly; perceived angular velocity depends strongly on the distance of the dots relative to the center of rotation. We suggest that the estimation of rotary motion is mediated by local estimations of linear velocity.

A Balanced Comparison of Object Invariances in Monkey IT Neurons

PubMed Central

2017-01-01

Abstract Our ability to recognize objects across variations in size, position, or rotation is based on invariant object representations in higher visual cortex. However, we know little about how these invariances are related. Are some invariances harder than others? Do some invariances arise faster than others? These comparisons can be made only upon equating image changes across transformations. Here, we targeted invariant neural representations in the monkey inferotemporal (IT) cortex using object images with balanced changes in size, position, and rotation. Across the recorded population, IT neurons generalized across size and position both stronger and faster than to rotations in the image plane as well as in depth. We obtained a similar ordering of invariances in deep neural networks but not in low-level visual representations. Thus, invariant neural representations dynamically evolve in a temporal order reflective of their underlying computational complexity. PMID:28413827

Partial rotator cuff repair and biceps tenotomy for the treatment of patients with massive cuff tears and retained overhead elevation: midterm outcomes with a minimum 5 years of follow-up.

PubMed

Cuff, Derek J; Pupello, Derek R; Santoni, Brandon G

2016-11-01

A subset of patients with massive irreparable rotator cuff tears present with retained overhead elevation and pain as their primary complaint. Our aim was to evaluate the outcomes of partial arthroscopic rotator cuff repair with biceps tenotomy and to report the failure rate of this procedure for patients with >5 years of follow-up. Thirty-four patients underwent partial rotator cuff repair and biceps tenotomy for treatment of a massive rotator cuff tear. Patients had preoperative active forward elevation >120° and no radiographic evidence of glenohumeral arthritis. Patients were followed up clinically and radiographically, and 28 patients had a minimum of 5 years of follow-up. Failure was defined as an American Shoulder and Elbow Surgeons score of <70, loss of active elevation >90°, or revision to reverse shoulder arthroplasty during the study period. Patients demonstrated improvements in average preoperative to postoperative American Shoulder and Elbow Surgeons scores (46.6 to 79.3 [P < .001]) and Simple Shoulder Test scores (5.7 to 9.1 [P < .001]) along with decrease in visual analog scale for pain scores (6.9 to 1.9 [P < .001]). No significant change in forward elevation (168° to 154° [P = .07]), external rotation (38° to 39° [P = 1.0]), or internal rotation (84% to 80% [P = 1.0]) was identified; 36% of patients had progression of the Hamada stage. The failure rate was 29%; 75% of patients were satisfied with their index procedure. Partial rotator cuff repair and biceps tenotomy for patients with massive irreparable rotator cuff tears with retained overhead elevation and pain as the primary complaint produced reasonable outcomes at midterm follow-up of at least 5 years. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Illusory Motion Reproduced by Deep Neural Networks Trained for Prediction

PubMed Central

Watanabe, Eiji; Kitaoka, Akiyoshi; Sakamoto, Kiwako; Yasugi, Masaki; Tanaka, Kenta

2018-01-01

The cerebral cortex predicts visual motion to adapt human behavior to surrounding objects moving in real time. Although the underlying mechanisms are still unknown, predictive coding is one of the leading theories. Predictive coding assumes that the brain's internal models (which are acquired through learning) predict the visual world at all times and that errors between the prediction and the actual sensory input further refine the internal models. In the past year, deep neural networks based on predictive coding were reported for a video prediction machine called PredNet. If the theory substantially reproduces the visual information processing of the cerebral cortex, then PredNet can be expected to represent the human visual perception of motion. In this study, PredNet was trained with natural scene videos of the self-motion of the viewer, and the motion prediction ability of the obtained computer model was verified using unlearned videos. We found that the computer model accurately predicted the magnitude and direction of motion of a rotating propeller in unlearned videos. Surprisingly, it also represented the rotational motion for illusion images that were not moving physically, much like human visual perception. While the trained network accurately reproduced the direction of illusory rotation, it did not detect motion components in negative control pictures wherein people do not perceive illusory motion. This research supports the exciting idea that the mechanism assumed by the predictive coding theory is one of basis of motion illusion generation. Using sensory illusions as indicators of human perception, deep neural networks are expected to contribute significantly to the development of brain research. PMID:29599739

The performance & flow visualization studies of three-dimensional (3-D) wind turbine blade models

NASA Astrophysics Data System (ADS)

Sutrisno, Prajitno, Purnomo, W., Setyawan B.

2016-06-01

Recently, studies on the design of 3-D wind turbine blades have a less attention even though 3-D blade products are widely sold. In contrary, advanced studies in 3-D helicopter blade tip have been studied rigorously. Studies in wind turbine blade modeling are mostly assumed that blade spanwise sections behave as independent two-dimensional airfoils, implying that there is no exchange of momentum in the spanwise direction. Moreover, flow visualization experiments are infrequently conducted. Therefore, a modeling study of wind turbine blade with visualization experiment is needed to be improved to obtain a better understanding. The purpose of this study is to investigate the performance of 3-D wind turbine blade models with backward-forward swept and verify the flow patterns using flow visualization. In this research, the blade models are constructed based on the twist and chord distributions following Schmitz's formula. Forward and backward swept are added to the rotating blades. Based on this, the additional swept would enhance or diminish outward flow disturbance or stall development propagation on the spanwise blade surfaces to give better blade design. Some combinations, i. e., b lades with backward swept, provide a better 3-D favorable rotational force of the rotor system. The performance of the 3-D wind turbine system model is measured by a torque meter, employing Prony's braking system. Furthermore, the 3-D flow patterns around the rotating blade models are investigated by applying "tuft-visualization technique", to study the appearance of laminar, separated, and boundary layer flow patterns surrounding the 3-dimentional blade system.

Illusory Motion Reproduced by Deep Neural Networks Trained for Prediction.

PubMed

Watanabe, Eiji; Kitaoka, Akiyoshi; Sakamoto, Kiwako; Yasugi, Masaki; Tanaka, Kenta

2018-01-01

The cerebral cortex predicts visual motion to adapt human behavior to surrounding objects moving in real time. Although the underlying mechanisms are still unknown, predictive coding is one of the leading theories. Predictive coding assumes that the brain's internal models (which are acquired through learning) predict the visual world at all times and that errors between the prediction and the actual sensory input further refine the internal models. In the past year, deep neural networks based on predictive coding were reported for a video prediction machine called PredNet. If the theory substantially reproduces the visual information processing of the cerebral cortex, then PredNet can be expected to represent the human visual perception of motion. In this study, PredNet was trained with natural scene videos of the self-motion of the viewer, and the motion prediction ability of the obtained computer model was verified using unlearned videos. We found that the computer model accurately predicted the magnitude and direction of motion of a rotating propeller in unlearned videos. Surprisingly, it also represented the rotational motion for illusion images that were not moving physically, much like human visual perception. While the trained network accurately reproduced the direction of illusory rotation, it did not detect motion components in negative control pictures wherein people do not perceive illusory motion. This research supports the exciting idea that the mechanism assumed by the predictive coding theory is one of basis of motion illusion generation. Using sensory illusions as indicators of human perception, deep neural networks are expected to contribute significantly to the development of brain research.

Aging effect on step adjustments and stability control in visually perturbed gait initiation.

PubMed

Sun, Ruopeng; Cui, Chuyi; Shea, John B

2017-10-01

Gait adaptability is essential for fall avoidance during locomotion. It requires the ability to rapidly inhibit original motor planning, select and execute alternative motor commands, while also maintaining the stability of locomotion. This study investigated the aging effect on gait adaptability and dynamic stability control during a visually perturbed gait initiation task. A novel approach was used such that the anticipatory postural adjustment (APA) during gait initiation were used to trigger the unpredictable relocation of a foot-size stepping target. Participants (10 young adults and 10 older adults) completed visually perturbed gait initiation in three adjustment timing conditions (early, intermediate, late; all extracted from the stereotypical APA pattern) and two adjustment direction conditions (medial, lateral). Stepping accuracy, foot rotation at landing, and Margin of Dynamic Stability (MDS) were analyzed and compared across test conditions and groups using a linear mixed model. Stepping accuracy decreased as a function of adjustment timing as well as stepping direction, with older subjects exhibited a significantly greater undershoot in foot placement to late lateral stepping. Late adjustment also elicited a reaching-like movement (i.e. foot rotation prior to landing in order to step on the target), regardless of stepping direction. MDS measures in the medial-lateral and anterior-posterior direction revealed both young and older adults exhibited reduced stability in the adjustment step and subsequent steps. However, young adults returned to stable gait faster than older adults. These findings could be useful for future study of screening deficits in gait adaptability and preventing falls. Copyright © 2017 Elsevier B.V. All rights reserved.

Laser spectroscopic visualization of hydrogen bond motions in liquid water

NASA Astrophysics Data System (ADS)

Bratos, S.; Leicknam, J.-Cl.; Pommeret, S.; Gallot, G.

2004-12-01

Ultrafast pump-probe experiments are described permitting a visualization of molecular motions in diluted HDO/D 2O solutions. The experiments were realized in the mid-infrared spectral region with a time resolution of 150 fs. They were interpreted by a careful theoretical analysis, based on the correlation function approach of statistical mechanics. Combining experiment and theory, stretching motions of the OH⋯O bonds as well as HDO rotations were 'filmed' in real time. It was found that molecular rotations are the principal agent of hydrogen bond breaking and making in water. Recent literatures covering the subject, including molecular dynamics simulations, are reviewed in detail.

Discrimination of holograms and real objects by pigeons (Columba livia) and humans (Homo sapiens).

PubMed

Stephan, Claudia; Steurer, Michael M; Aust, Ulrike

2014-08-01

The type of stimulus material employed in visual tasks is crucial to all comparative cognition research that involves object recognition. There is considerable controversy about the use of 2-dimensional stimuli and the impact that the lack of the 3rd dimension (i.e., depth) may have on animals' performance in tests for their visual and cognitive abilities. We report evidence of discrimination learning using a completely novel type of stimuli, namely, holograms. Like real objects, holograms provide full 3-dimensional shape information but they also offer many possibilities for systematically modifying the appearance of a stimulus. Hence, they provide a promising means for investigating visual perception and cognition of different species in a comparative way. We trained pigeons and humans to discriminate either between 2 real objects or between holograms of the same 2 objects, and we subsequently tested both species for the transfer of discrimination to the other presentation mode. The lack of any decrements in accuracy suggests that real objects and holograms were perceived as equivalent in both species and shows the general appropriateness of holograms as stimuli in visual tasks. A follow-up experiment involving the presentation of novel views of the training objects and holograms revealed some interspecies differences in rotational invariance, thereby confirming and extending the results of previous studies. Taken together, these results suggest that holograms may not only provide a promising tool for investigating yet unexplored issues, but their use may also lead to novel insights into some crucial aspects of comparative visual perception and categorization.

Effects of high- and low-energy radial shock waves therapy combined with physiotherapy in the treatment of rotator cuff tendinopathy: a retrospective study.

PubMed

Su, Xiangzheng; Li, Zhongli; Liu, Zhengsheng; Shi, Teng; Xue, Chao

2017-06-09

The aim of this study was to investigate the efficacy of high- and low-energy radial shock waves combined with physiotherapy for rotator cuff tendinopathy patients. Data from rotator cuff tendinopathy patients received high- or low-energy radial shock waves combined with physiotherapy or physiotherapy alone were collected. The Constant and Murley score and visual analog scale score were collected to assess the effectiveness of treatment in three groups at 4, 8, 12, and 24 weeks. In total, 94 patients were involved for our retrospective study. All groups showed remarkable improvement in the visual analog scale and Constant and Murley score compared to baseline at 24 weeks. The high-energy radial shock waves group had more marked improvement in the Constant and Murley score compared to the physiotherapy group at 4 and 8 weeks and at 4 weeks when compared with low-energy group. Furthermore, high-energy radial shock waves group had superior results on the visual analog scale at 4, 8, and 12 weeks compared to low-energy and physiotherapy groups. This retrospective study supported the usage of high-energy radial shock waves as a supplementary therapy over physiotherapy alone for rotator cuff tendinopathy by relieving the symptoms rapidly and maintaining symptoms at a satisfactory level for 24 weeks. Implications for Rehabilitation High-energy radial shock waves can be a supplemental therapy to physiotherapy for rotator cuff tendinopathy. We recommend the usage of high-energy radial shock waves during the first 5 weeks, at an interval of 7 days, of physiotherapy treatment. High-energy radial shock waves treatment combined with physiotherapy can benefit rotator cuff tendinopathy by relieving symptoms rapidly and maintain these improvements at a satisfactory level for quite a long time.

Does immobilization after arthroscopic rotator cuff repair increase tendon healing? A systematic review and meta-analysis.

PubMed

Shen, Chong; Tang, Zhi-Hong; Hu, Jun-Zu; Zou, Guo-Yao; Xiao, Rong-Chi; Yan, Dong-Xue

2014-09-01

To determine whether immobilization after arthroscopic rotator cuff repair improved tendon healing compared with early passive motion. A systematic electronic literature search was conducted to identify randomized controlled trials (RCTs) comparing early passive motion with immobilization after arthroscopic rotator cuff repair. The primary outcome assessed was tendon healing in the repaired cuff. Secondary outcome measures were range of motion (ROM) and American Shoulder and Elbow Surgeons (ASES) shoulder scale, Simple Shoulder Test (SST), Constant, and visual analog scale (VAS) for pain scores. Pooled analyses were performed using a random effects model to obtain summary estimates of treatment effect with 95% confidence intervals. Heterogeneity among included studies was quantified. Three RCTs examining 265 patients were included. Meta-analysis revealed no significant difference in tendon healing in the repaired cuff between the early-motion and immobilization groups. A significant difference in external rotation at 6 months postoperatively favored early motion over immobilization, but no significant difference was observed at 1 year postoperatively. In one study, Constant scores were slightly higher in the early-motion group than in the immobilization group. Two studies found no significant difference in ASES, SST, or VAS score between groups. We found no evidence that immobilization after arthroscopic rotator cuff repair was superior to early-motion rehabilitation in terms of tendon healing or clinical outcome. Patients in the early-motion group may recover ROM more rapidly. Level II; systematic review of levels I and II studies.

Research on measurement of aviation magneto ignition strength and balance

NASA Astrophysics Data System (ADS)

Gao, Feng; He, Zhixiang; Zhang, Dingpeng

2017-12-01

Aviation magneto ignition system failure accounted for two-thirds of the total fault aviation piston engine and above. At present the method used for this failure diagnosis is often depended on the visual inspections in the civil aviation maintenance field. Due to human factors, the visual inspections cannot provide ignition intensity value and ignition equilibrium deviation value among the different spark plugs in the different cylinder of aviation piston engine. So air magneto ignition strength and balance testing has become an aviation piston engine maintenance technical problem needed to resolve. In this paper, the ultraviolet sensor with detection wavelength of 185~260nm and driving voltage of 320V DC is used as the core of ultraviolet detection to detect the ignition intensity of Aviation magneto ignition system and the balance deviation of the ignition intensity of each cylinder. The experimental results show that the rotational speed within the range 0 to 3500 RPM test error less than 0.34%, ignition strength analysis and calculation error is less than 0.13%, and measured the visual inspection is hard to distinguish between high voltage wire leakage failure of deviation value of 200 pulse ignition strength balance/Sec. The method to detect aviation piston engine maintenance of magneto ignition system fault has a certain reference value.

Interferometry of chemically peculiar stars: theoretical predictions versus modern observing facilities

NASA Astrophysics Data System (ADS)

Shulyak, D.; Paladini, C.; Causi, G. Li; Perraut, K.; Kochukhov, O.

2014-09-01

By means of numerical experiments we explore the application of interferometry to the detection and characterization of abundance spots in chemically peculiar (CP) stars using the brightest star ε UMa as a case study. We find that the best spectral regions to search for spots and stellar rotation signatures are in the visual domain. The spots can clearly be detected already at a first visibility lobe and their signatures can be uniquely disentangled from that of rotation. The spots and rotation signatures can also be detected in near-infrared at low spectral resolution but baselines longer than 180 m are needed for all potential CP candidates. According to our simulations, an instrument like VEGA (or its successor e.g. Fibered and spectrally Resolved Interferometric Equipment New Design) should be able to detect, in the visual, the effect of spots and spots+rotation, provided that the instrument is able to measure V2 ≈ 10-3, and/or closure phase. In infrared, an instrument like AMBER but with longer baselines than the ones available so far would be able to measure rotation and spots. Our study provides necessary details about strategies of spot detections and the requirements for modern and planned interferometric facilities essential for CP star research.

Turbulent structures in cylindrical density currents in a rotating frame of reference

NASA Astrophysics Data System (ADS)

Salinas, Jorge S.; Cantero, Mariano I.; Dari, Enzo A.; Bonometti, Thomas

2018-06-01

Gravity currents are flows generated by the action of gravity on fluids with different densities. In some geophysical applications, modeling such flows makes it necessary to account for rotating effects, modifying the dynamics of the flow. While previous works on rotating stratified flows focused on currents of large Coriolis number, the present work focuses on flows with small Coriolis numbers (i.e. moderate-to-large Rossby numbers). In this work, cylindrical rotating gravity currents are investigated by means of highly resolved simulations. A brief analysis of the mean flow evolution to the final state is presented to provide a complete picture of the flow dynamics. The numerical results, showing the well-known oscillatory behavior of the flow (inertial waves) and a final state lens shape (geostrophic adjustment), are in good agreement with experimental observations and theoretical models. The turbulent structures in the flow are visualized and described using, among others, a stereoscopic visualization and videos as supplementary material. In particular, the structure of the lobes and clefts at the front of the current is presented in association to local turbulent structures. In rotating gravity currents, the vortices observed at the lobes front are not of hairpin type but are rather of Kelvin-Helmholtz type.

[Preliminary construction of three-dimensional visual educational system for clinical dentistry based on world wide web webpage].

PubMed

Hu, Jian; Xu, Xiang-yang; Song, En-min; Tan, Hong-bao; Wang, Yi-ning

2009-09-01

To establish a new visual educational system of virtual reality for clinical dentistry based on world wide web (WWW) webpage in order to provide more three-dimensional multimedia resources to dental students and an online three-dimensional consulting system for patients. Based on computer graphics and three-dimensional webpage technologies, the software of 3Dsmax and Webmax were adopted in the system development. In the Windows environment, the architecture of whole system was established step by step, including three-dimensional model construction, three-dimensional scene setup, transplanting three-dimensional scene into webpage, reediting the virtual scene, realization of interactions within the webpage, initial test, and necessary adjustment. Five cases of three-dimensional interactive webpage for clinical dentistry were completed. The three-dimensional interactive webpage could be accessible through web browser on personal computer, and users could interact with the webpage through rotating, panning and zooming the virtual scene. It is technically feasible to implement the visual educational system of virtual reality for clinical dentistry based on WWW webpage. Information related to clinical dentistry can be transmitted properly, visually and interactively through three-dimensional webpage.

Development of the Wake Behind a Circular Cylinder Impulsively Started into Rotatory and Rectilinear Motion: Intermediate Rotation Rates

DTIC Science & Technology

1991-01-01

cylindre fixe ou en rotation. Effet Magnus . J. Mec. 14, 109-134. Taneda, S. 1977 Visual study of unsteady separated flows around bodies. Prog. Aero...enhancement schemes employing the Magnus effect (Swanson 1961). Rotating all or part of a body may also have applications in active or feedback control of...and yt into the governing equations in the generalized coordinate system. In this study, the body-fitted grid is simply one of cylindrical polar

Visual Priming of Inverted and Rotated Objects

ERIC Educational Resources Information Center

Knowlton, Barbara J.; McAuliffe, Sean P.; Coelho, Chase J.; Hummel, John E.

2009-01-01

Object images are identified more efficiently after prior exposure. Here, the authors investigated shape representations supporting object priming. The dependent measure in all experiments was the minimum exposure duration required to correctly identify an object image in a rapid serial visual presentation stream. Priming was defined as the change…

Spatial attention increases high-frequency gamma synchronisation in human medial visual cortex.

PubMed

Koelewijn, Loes; Rich, Anina N; Muthukumaraswamy, Suresh D; Singh, Krish D

2013-10-01

Visual information processing involves the integration of stimulus and goal-driven information, requiring neuronal communication. Gamma synchronisation is linked to neuronal communication, and is known to be modulated in visual cortex both by stimulus properties and voluntarily-directed attention. Stimulus-driven modulations of gamma activity are particularly associated with early visual areas such as V1, whereas attentional effects are generally localised to higher visual areas such as V4. The absence of a gamma increase in early visual cortex is at odds with robust attentional enhancements found with other measures of neuronal activity in this area. Here we used magnetoencephalography (MEG) to explore the effect of spatial attention on gamma activity in human early visual cortex using a highly effective gamma-inducing stimulus and strong attentional manipulation. In separate blocks, subjects tracked either a parafoveal grating patch that induced gamma activity in contralateral medial visual cortex, or a small line at fixation, effectively attending away from the gamma-inducing grating. Both items were always present, but rotated unpredictably and independently of each other. The rotating grating induced gamma synchronisation in medial visual cortex at 30-70 Hz, and in lateral visual cortex at 60-90 Hz, regardless of whether it was attended. Directing spatial attention to the grating increased gamma synchronisation in medial visual cortex, but only at 60-90 Hz. These results suggest that the generally found increase in gamma activity by spatial attention can be localised to early visual cortex in humans, and that stimulus and goal-driven modulations may be mediated at different frequencies within the gamma range. Copyright © 2013 Elsevier Inc. All rights reserved.

Vestibular responses in the macaque pedunculopontine nucleus and central mesencephalic reticular formation

PubMed Central

Aravamuthan, Bhooma R.; Angelaki, Dora E.

2012-01-01

The pedunculopontine nucleus (PPN) and central mesencephalic reticular formation (cMRF) both send projections and receive input from areas with known vestibular responses. Noting their connections with the basal ganglia, the locomotor disturbances that occur following lesions of the PPN or cMRF, and the encouraging results of PPN deep brain stimulation in Parkinson’s disease patients, both the PPN and cMRF have been linked to motor control. In order to determine the existence of and characterize vestibular responses in the PPN and cMRF, we recorded single neurons from both structures during vertical and horizontal rotation, translation, and visual pursuit stimuli. The majority of PPN cells (72.5%) were vestibular-only cells that responded exclusively to rotation and translation stimuli but not visual pursuit. Visual pursuit responses were much more prevalent in the cMRF (57.1%) though close to half of cMRF cells were vestibular-only cells (41.1%). Directional preferences also differed between the PPN, which was preferentially modulated during nose-down pitch, and cMRF, which was preferentially modulated during ipsilateral yaw rotation. Finally, amplitude responses were similar between the PPN and cMRF during rotation and pursuit stimuli, but PPN responses to translation were of higher amplitude than cMRF responses. Taken together with their connections to the vestibular circuit, these results implicate the PPN and cMRF in the processing of vestibular stimuli and suggest important roles for both in responding to motion perturbations like falls and turns. PMID:22864184

Spatial abilities, Earth science conceptual understanding, and psychological gender of university non-science majors

NASA Astrophysics Data System (ADS)

Black, Alice A. (Jill)

Research has shown the presence of many Earth science misconceptions and conceptual difficulties that may impede concept understanding, and has also identified a number of categories of spatial ability. Although spatial ability has been linked to high performance in science, some researchers believe it has been overlooked in traditional education. Evidence exists that spatial ability can be improved. This correlational study investigated the relationship among Earth science conceptual understanding, three types of spatial ability, and psychological gender, a self-classification that reflects socially-accepted personality and gender traits. A test of Earth science concept understanding, the Earth Science Concepts (ESC) test, was developed and field tested from 2001 to 2003 in 15 sections of university classes. Criterion validity was .60, significant at the .01 level. Spearman/Brown reliability was .74 and Kuder/Richardson reliability was .63. The Purdue Visualization of Rotations (PVOR) (mental rotation), the Group Embedded Figures Test (GEFT) (spatial perception), the Differential Aptitude Test: Space Relations (DAT) (spatial visualization), and the Bem Inventory (BI) (psychological gender) were administered to 97 non-major university students enrolled in undergraduate science classes. Spearman correlations revealed moderately significant correlations at the .01 level between ESC scores and each of the three spatial ability test scores. Stepwise regression analysis indicated that PVOR scores were the best predictor of ESC scores, and showed that spatial ability scores accounted for 27% of the total variation in ESC scores. Spatial test scores were moderately or weakly correlated with each other. No significant correlations were found among BI scores and other test scores. Scantron difficulty analysis of ESC items produced difficulty ratings ranging from 33.04 to 96.43, indicating the percentage of students who answered incorrectly. Mean score on the ESC was 34%, indicating that the non-majors tested exhibited many Earth science misconceptions and conceptual difficulties. A number of significant results were found when independent t-tests and correlations were conducted among test scores and demographic variables. The number of previous university Earth science courses was significantly related to ESC scores. Preservice elementary/middle majors differed significantly in several ways from other non-majors, and several earlier results were not supported. Results of this study indicate that an important opportunity may exist to improve Earth science conceptual understanding by focusing on spatial ability, a cognitive ability that has heretofore not been directly addressed in schools.

Imagery May Arise from Associations Formed through Sensory Experience: A Network of Spiking Neurons Controlling a Robot Learns Visual Sequences in Order to Perform a Mental Rotation Task

PubMed Central

McKinstry, Jeffrey L.; Fleischer, Jason G.; Chen, Yanqing; Gall, W. Einar; Edelman, Gerald M.

2016-01-01

Mental imagery occurs “when a representation of the type created during the initial phases of perception is present but the stimulus is not actually being perceived.” How does the capability to perform mental imagery arise? Extending the idea that imagery arises from learned associations, we propose that mental rotation, a specific form of imagery, could arise through the mechanism of sequence learning–that is, by learning to regenerate the sequence of mental images perceived while passively observing a rotating object. To demonstrate the feasibility of this proposal, we constructed a simulated nervous system and embedded it within a behaving humanoid robot. By observing a rotating object, the system learns the sequence of neural activity patterns generated by the visual system in response to the object. After learning, it can internally regenerate a similar sequence of neural activations upon briefly viewing the static object. This system learns to perform a mental rotation task in which the subject must determine whether two objects are identical despite differences in orientation. As with human subjects, the time taken to respond is proportional to the angular difference between the two stimuli. Moreover, as reported in humans, the system fills in intermediate angles during the task, and this putative mental rotation activates the same pathways that are activated when the system views physical rotation. This work supports the proposal that mental rotation arises through sequence learning and the idea that mental imagery aids perception through learned associations, and suggests testable predictions for biological experiments. PMID:27653977

Mental Rotation Meets the Motion Aftereffect: The Role of hV5/MT+ in Visual Mental Imagery

ERIC Educational Resources Information Center

Seurinck, Ruth; de Lange, Floris P.; Achten, Erik; Vingerhoets, Guy

2011-01-01

A growing number of studies show that visual mental imagery recruits the same brain areas as visual perception. Although the necessity of hV5/MT+ for motion perception has been revealed by means of TMS, its relevance for motion imagery remains unclear. We induced a direction-selective adaptation in hV5/MT+ by means of an MAE while subjects…

Evaluation of Postural Control in Patients with Glaucoma Using a Virtual Reality Environment.

PubMed

Diniz-Filho, Alberto; Boer, Erwin R; Gracitelli, Carolina P B; Abe, Ricardo Y; van Driel, Nienke; Yang, Zhiyong; Medeiros, Felipe A

2015-06-01

To evaluate postural control using a dynamic virtual reality environment and the relationship between postural metrics and history of falls in patients with glaucoma. Cross-sectional study. The study involved 42 patients with glaucoma with repeatable visual field defects on standard automated perimetry (SAP) and 38 control healthy subjects. Patients underwent evaluation of postural stability by a force platform during presentation of static and dynamic visual stimuli on stereoscopic head-mounted goggles. The dynamic visual stimuli presented rotational and translational ecologically valid peripheral background perturbations. Postural stability was also tested in a completely dark field to assess somatosensory and vestibular contributions to postural control. History of falls was evaluated by a standard questionnaire. Torque moments around the center of foot pressure on the force platform were measured, and the standard deviations of the torque moments (STD) were calculated as a measurement of postural stability and reported in Newton meters (Nm). The association with history of falls was investigated using Poisson regression models. Age, gender, body mass index, severity of visual field defect, best-corrected visual acuity, and STD on dark field condition were included as confounding factors. Patients with glaucoma had larger overall STD than controls during both translational (5.12 ± 2.39 Nm vs. 3.85 ± 1.82 Nm, respectively; P = 0.005) and rotational stimuli (5.60 ± 3.82 Nm vs. 3.93 ± 2.07 Nm, respectively; P = 0.022). Postural metrics obtained during dynamic visual stimuli performed better in explaining history of falls compared with those obtained in static and dark field condition. In the multivariable model, STD values in the mediolateral direction during translational stimulus were significantly associated with a history of falls in patients with glaucoma (incidence rate ratio, 1.85; 95% confidence interval, 1.30-2.63; P = 0.001). The study presented and validated a novel paradigm for evaluation of balance control in patients with glaucoma on the basis of the assessment of postural reactivity to dynamic visual stimuli using a virtual reality environment. The newly developed metrics were associated with a history of falls and may help to provide a better understanding of balance control in patients with glaucoma. Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Evaluation of Postural Control in Glaucoma Patients Using a Virtual 1 Reality Environment

PubMed Central

Diniz-Filho, Alberto; Boer, Erwin R.; Gracitelli, Carolina P. B.; Abe, Ricardo Y.; van Driel, Nienke; Yang, Zhiyong; Medeiros, Felipe A.

2015-01-01

Purpose To evaluate postural control using a dynamic virtual reality environment and the relationship between postural metrics and history of falls in glaucoma patients. Design Cross-sectional study. Participants The study involved 42 glaucoma patients with repeatable visual field defects on standard automated perimetry (SAP) and 38 control healthy subjects. Methods Patients underwent evaluation of postural stability by a force platform during presentation of static and dynamic visual stimuli on stereoscopic head-mounted goggles. The dynamic visual stimuli presented rotational and translational ecologically valid peripheral background perturbations. Postural stability was also tested in a completely dark field to assess somatosensory and vestibular contributions to postural control. History of falls was evaluated by a standard questionnaire. Main Outcome Measures Torque moments around the center of foot pressure on the force platform were measured and the standard deviations (STD) of these torque moments were calculated as a measurement of postural stability and reported in Newton meter (Nm). The association with history of falls was investigated using Poisson regression models. Age, gender, body mass index, severity of visual field defect, best-corrected visual acuity, and STD on dark field condition were included as confounding factors. Results Glaucoma patients had larger overall STD than controls during both translational (5.12 ± 2.39 Nm vs. 3.85 ± 1.82 Nm, respectively; P = 0.005) as well as rotational stimuli (5.60 ± 3.82 Nm vs. 3.93 ± 2.07 Nm, respectively; P = 0.022). Postural metrics obtained during dynamic visual stimuli performed better in explaining history of falls compared to those obtained in static and dark field condition. In the multivariable model, STD values in the mediolateral direction during translational stimulus were significantly associated with history of falls in glaucoma patients (incidence-rate ratio = 1.85; 95% CI: 1.30 – 2.63; P = 0.001). Conclusions The study presented and validated a novel paradigm for evaluation of balance control in glaucoma patients based on the assessment of postural reactivity to dynamic visual stimuli using a virtual reality environment. The newly developed metrics were associated with history of falls and may help to provide a better understanding of balance control in glaucoma patients. PMID:25892017

Dynamic Paper Constructions for Easier Visualization of Molecular Symmetry

ERIC Educational Resources Information Center

Sein, Lawrence T., Jr.

2010-01-01

A system for construction of simple poster-board models is described. The models dynamically demonstrate the symmetry operations of proper rotation, improper rotation, reflection, and inversion for the chemically important point groups D[subscript 3h], D[subscript 4h], D[subscript 5h], D[subscript 6h], T[subscript d], and O[subscript h]. The…

Azimuthal phase retardation microscope for visualizing actin filaments of biological cells

NASA Astrophysics Data System (ADS)

Shin, In Hee; Shin, Sang-Mo

2011-09-01

We developed a new theory-based azimuthal phase retardation microscope to visualize distributions of actin filaments in biological cells without having them with exogenous dyes, fluorescence labels, or stains. The azimuthal phase retardation microscope visualizes distributions of actin filaments by measuring the intensity variations of each pixel of a charge coupled device camera while rotating a single linear polarizer. Azimuthal phase retardation δ between two fixed principal axes was obtained by calculating the rotation angles of the polarizer at the intensity minima from the acquired intensity data. We have acquired azimuthal phase retardation distributions of human breast cancer cell, MDA MB 231 by our microscope and compared the azimuthal phase retardation distributions with the fluorescence image of actin filaments by the commercial fluorescence microscope. Also, we have observed movement of human umbilical cord blood derived mesenchymal stem cells by measuring azimuthal phase retardation distributions.

Vortex formation and saturation for low-aspect-ratio rotating flat-plate fins

NASA Astrophysics Data System (ADS)

Devoria, Adam C.; Ringuette, Matthew J.

2012-02-01

We investigate experimentally the unsteady, three-dimensional vortex formation of low-aspect-ratio, trapezoidal flat-plate fins undergoing rotation from rest at a 90° angle of attack and Reynolds numbers of O(103). The objectives are to characterize the unsteady three-dimensional vortex structure, examine vortex saturation, and understand the effects of the root-to-tip flow for different velocity programs. The experiments are conducted in a water tank facility, and the diagnostic tools are dye flow visualization and digital particle image velocimetry. The dye visualizations show that the low-aspect-ratio plate produces symmetric ring-like vortices comprised mainly of tip-edge vorticity. They also indicate the presence of the root-to-tip velocity. For large rotational amplitudes, the primary ring-like vortex sheds and a secondary ring-like vortex is generated while the plate is still in motion, indicating saturation of the leading vortex. The time-varying vortex circulation in the flow symmetry plane provides quantitative evidence of vortex saturation. The phenomenon of saturation is observed for several plate velocity programs. The temporal development of the vortex circulation is often complex, which prevents an objective determination of an exact saturation time. This is the result of an interaction between the developing vortex and the root-to-tip flow, which breaks apart the vortex. However, it is possible to define a range of time during which the vortex reaches saturation. A formation-parameter definition is investigated and is found to reasonably predict the state corresponding to the pinch-off of the initial tip vortex across the velocity programs tested. This event is the lower bound on the saturation time range.

The effect of multispectral image fusion enhancement on human efficiency.

PubMed

Bittner, Jennifer L; Schill, M Trent; Mohd-Zaid, Fairul; Blaha, Leslie M

2017-01-01

The visual system can be highly influenced by changes to visual presentation. Thus, numerous techniques have been developed to augment imagery in an attempt to improve human perception. The current paper examines the potential impact of one such enhancement, multispectral image fusion, where imagery captured in varying spectral bands (e.g., visible, thermal, night vision) is algorithmically combined to produce an output to strengthen visual perception. We employ ideal observer analysis over a series of experimental conditions to (1) establish a framework for testing the impact of image fusion over the varying aspects surrounding its implementation (e.g., stimulus content, task) and (2) examine the effectiveness of fusion on human information processing efficiency in a basic application. We used a set of rotated Landolt C images captured with a number of individual sensor cameras and combined across seven traditional fusion algorithms (e.g., Laplacian pyramid, principal component analysis, averaging) in a 1-of-8 orientation task. We found that, contrary to the idea of fused imagery always producing a greater impact on perception, single-band imagery can be just as influential. Additionally, efficiency data were shown to fluctuate based on sensor combination instead of fusion algorithm, suggesting the need for examining multiple factors to determine the success of image fusion. Our use of ideal observer analysis, a popular technique from the vision sciences, provides not only a standard for testing fusion in direct relation to the visual system but also allows for comparable examination of fusion across its associated problem space of application.

Investigating the impact of innate dexterity skills and visuospatial aptitude on the performance of baseline laparoscopic skills in veterinary students.

PubMed

MacCormick, Mathew R A; Kilkenny, Jessica J; Walker, Meagan; Zur Linden, Alex; Singh, Ameet

2017-11-01

To determine if manual dexterity and visuospatial skills can be used to predict baseline laparoscopic surgery skills in veterinary students. Pilot study. Veterinary students (n = 45) from years 1-4 volunteered for this study. An hour-long electronic questionnaire was completed by participants. The first section was used to collect demographics and information about prior nonsurgical experiences. The second section included 3 tests of visuospatial skills, including the Purdue Visualization of Rotations Test, Mental Rotations Test, and Raven's Advanced Progressive Matrices Test. Multiple tests were administered to assess innate dexterity, including the grooved pegboard test, indirect and direct zigzag tracking tests, and the 3Dconnexion proficiency test. Each dexterity test was performed once with the left hand and once with the right hand. The order of task performance was randomized. Basic laparoscopic skills were assessed using the validated fundamentals of laparoscopic surgery (FLS) peg transfer task. There was an association between left-handed grooved pegboard scores (95% CI -10046.36 to -1636.53, P-value = .008) and left-handed indirect zigzag tracking task (95% CI -35.78 to -8.20, P-value = .003) with FLS peg transfer scores. Individuals who reported playing videogames achieved higher scores on the FLS peg transfer task than those without videogame experience (95% CI 583.59 to 3509.97, P-value = .007). The results of this study suggest that dexterity was a better predictor of baseline laparoscopic skills than visuospatial skills in veterinary students. © 2017 The American College of Veterinary Surgeons.

Visual and vestibular components of motion sickness.

PubMed

Eyeson-Annan, M; Peterken, C; Brown, B; Atchison, D

1996-10-01

The relative importance of visual and vestibular information in the etiology of motion sickness (MS) is not well understood, but these factors can be manipulated by inducing Coriolis and pseudo-Coriolis effects in experimental subjects. We hypothesized that visual and vestibular information are equivalent in producing MS. The experiments reported here aim, in part, to examine the relative influence of Coriolis and pseudo-Coriolis effects in inducing MS. We induced MS symptoms by combinations of whole body rotation and tilt, and environment rotation and tilt, in 22 volunteer subjects. Subjects participated in all of the experiments with at least 2 d between each experiment to dissipate after-effects. We recorded MS signs and symptoms when only visual stimulation was applied, when only vestibular stimulation was applied, and when both visual and vestibular stimulation were applied under specific conditions of whole body and environmental tilt. Visual stimuli produced more symptoms of MS than vestibular stimuli when only visual or vestibular stimuli were used (ANOVA F = 7.94, df = 1, 21 p = 0.01), but there was no significant difference in MS production when combined visual and vestibular stimulation were used to produce the Coriolis effect or pseudo-Coriolis effect (ANOVA: F = 0.40, df = 1, 21 p = 0.53). This was further confirmed by examination of the order in which the symptoms occurred and the lack of a correlation between previous experience and visually induced MS. Visual information is more important than vestibular input in causing MS when these stimuli are presented in isolation. In conditions where both visual and vestibular information are present, cross-coupling appears to occur between the pseudo-Coriolis effect and the Coriolis effect, as these two conditions are not significantly different in producing MS symptoms.

Motor learning and consolidation: the case of visuomotor rotation.

PubMed

Krakauer, John W

2009-01-01

Adaptation to visuomotor rotation is a particular form of motor learning distinct from force-field adaptation, sequence learning, and skill learning. Nevertheless, study of adaptation to visuomotor rotation has yielded a number of findings and principles that are likely of general importance to procedural learning and memory. First, rotation learning is implicit and appears to proceed through reduction in a visual prediction error generated by a forward model, such implicit adaptation occurs even when it is in conflict with an explicit task goal. Second, rotation learning is subject to different forms of interference: retrograde, anterograde through aftereffects, and contextual blocking of retrieval. Third, opposite rotations can be recalled within a short time interval without interference if implicit contextual cues (effector change) rather than explicit cues (color change) are used. Fourth, rotation learning consolidates both over time and with increased initial training (saturation learning).

Tools for experimental characterization of the non-uniform rotational distortion in intravascular OCT probes

NASA Astrophysics Data System (ADS)

Dufour, Marc L.; Bisaillon, Charles-Etienne; Lamouche, Guy; Vergnole, Sebastien; Hewko, Mark; D'Amours, Frédéric; Padioleau, Christian; Sowa, Michael

2011-03-01

The Industrial Material Institute (IMI) together with the Institute for Biodiagnostic (IBD) has developed its own optical catheters for cardiovascular imaging applications. Those catheters have been used experimentally in the in vitro coronary artery model of the Langendorff beating heart and in a percutaneous coronary intervention procedure in a porcine model. For some catheter designs, non-uniform rotational distortion (NURD) can be observed as expected from past experience with intra-vascular ultrasound (IVUS) catheters. A two-dimensional (2D) coronary artery test bench that simulates the path into the coronary arteries has been developed. The presence or absence of NURD can be assessed with the test bench using a custom-built cardiovascular Optical Coherence Tomography (OCT) imaging system. A square geometry instead of the circular shape of an artery is used to simulate the coronary arteries. Thereby, it is easier to visualize NURD when it is present. The accumulated torsion induced by the friction on the catheter is measured along the artery path. NURD is induced by the varying friction force that is balanced by the accumulated torsion force. The pullback force is measured and correlated with NURD observed in the 2D test bench. Finally, a model is presented to help understanding the mechanical constraint that leads to the friction force variations.

Mental object rotation and the planning of hand movements.

PubMed

Wohlschläger, A

2001-05-01

Recently, we showed that the simultaneous execution of rotational hand movements interferes with mental object rotation, provided that the axes of rotation coincide in space. We hypothesized that mental object rotation and the programming of rotational hand movements share a common process presumably involved in action planning. Two experiments are reported here that show that the mere planning of a rotational hand movement is sufficient to cause interference with mental object rotation. Subjects had to plan different spatially directed hand movements that they were asked to execute only after they had solved a mental object rotation task. Experiment 1 showed that mental object rotation was slower if hand movements were planned in a direction opposite to the presumed mental rotation direction, but only if the axes of hand rotation and mental object rotation were parallel in space. Experiment 2 showed that this interference occurred independent of the preparatory hand movements observed in Experiment 1. Thus, it is the planning of hand movements and not their preparation or execution that interferes with mental object rotation. This finding underlines the idea that mental object rotation is an imagined (covert) action, rather than a pure visual-spatial imagery task, and that the interference between mental object rotation and rotational hand movements is an interference between goals of actions.

[Refractive precision and objective quality of vision after toric lens implantation in cataract surgery].

PubMed

Debois, A; Nochez, Y; Bezo, C; Bellicaud, D; Pisella, P-J

2012-10-01

To study efficacy and predictability of toric IOL implantation for correction of preoperative corneal astigmatism by analysing spherocylindrical refractive precision and objective quality of vision. Prospective study of 13 eyes undergoing micro-incisional cataract surgery through a 1.8mm corneal incision with toric IOL implantation (Lentis L313T(®), Oculentis) to treat over one D of preoperative corneal astigmatism. Preoperative evaluation included keratometry, subjective refraction, and total and corneal aberrometry (KR-1(®), Topcon). Six months postoperatively, measurements included slit lamp photography, documenting IOL rotation, tilt or decentration, uncorrected visual acuity, best-corrected visual acuity and objective quality of vision measurement (OQAS(®) Visiometrics, Spain). Postoperatively, mean uncorrected distance visual acuity was 8.33/10 ± 1.91 (0.09 ± 0.11 LogMar). Mean postoperative refractive sphere was 0.13 ± 0.73 diopters. Mean refractive astigmatism was -0.66 ± 0.56 diopters with corneal astigmatism of 2.17 ± 0.68 diopters. Mean IOL rotation was 4.4° ± 3.6° (range 0° to 10°). Mean rotation of this IOL at 6 months was less than 5°, demonstrating stability of the optic within the capsular bag. Objective quality of vision measurements were consistent with subjective uncorrected visual acuity. Implantation of the L313T(®) IOL is safe and effective for correction of corneal astigmatism in 1.8mm micro-incisional cataract surgery. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Statistical studies in stellar rotation 2: A method of analyzing rotational coupling in double stars and an introduction to its applications

NASA Technical Reports Server (NTRS)

Bernacca, P. L.

1971-01-01

The correlation between the equatorial velocities of the components of double stars is studied from a statistical standpoint. A theory of rotational correlation is developed and discussed with regard to its applicability to existing observations. The theory is then applied to a sample of visual binaries which are the least studied for rotational coupling. Consideration of eclipsing systems and spectroscopic binaries is limited to show how the degrees of freedom in the spin parallelism problem can be reduced. The analysis lends support to the existence of synchronism in closely spaced binaries.

Rotation and direction judgment from visual images head-slaved in two and three degrees-of-freedom.

PubMed

Adelstein, B D; Ellis, S R

2000-03-01

The contribution to spatial awareness of adding a roll degree-of-freedom (DOF) to telepresence camera platform yaw and pitch was examined in an experiment where subjects judged direction and rotation of stationary target markers in a remote scene. Subjects viewed the scene via head-slaved camera images in a head-mounted display. Elimination of the roll DOF affected rotation judgment, but only at extreme yaw and pitch combinations, and did not affect azimuth and elevation judgement. Systematic azimuth overshoot occurred regardless of roll condition. Observed rotation misjudgments are explained by kinematic models for eye-head direction of gaze.

Fast-Moving Bacteria Self-Organize into Active Two-Dimensional Crystals of Rotating Cells

NASA Astrophysics Data System (ADS)

Petroff, Alexander P.; Wu, Xiao-Lun; Libchaber, Albert

2015-04-01

We investigate a new form of collective dynamics displayed by Thiovulum majus, one of the fastest-swimming bacteria known. Cells spontaneously organize on a surface into a visually striking two-dimensional hexagonal lattice of rotating cells. As each constituent cell rotates its flagella, it creates a tornadolike flow that pulls neighboring cells towards and around it. As cells rotate against their neighbors, they exert forces on one another, causing the crystal to rotate and cells to reorganize. We show how these dynamics arise from hydrodynamic and steric interactions between cells. We derive the equations of motion for a crystal, show that this model explains several aspects of the observed dynamics, and discuss the stability of these active crystals.

SECEC Research Grant 2008 II: Use of platelet- and leucocyte-rich fibrin (L-PRF) does not affect late rotator cuff tendon healing: a prospective randomized controlled study.

PubMed

Zumstein, Matthias A; Rumian, Adam; Thélu, Charles Édouard; Lesbats, Virginie; O'Shea, Kieran; Schaer, Michael; Boileau, Pascal

2016-01-01

Because the retear rate after rotator cuff repairs remains high, methods to improve healing are very much needed. Platelet-rich concentrates have been shown to enhance tenocyte proliferation and promote extracellular matrix synthesis in vitro; however, their clinical benefit remains unclear. We hypothesized that arthroscopic rotator cuff repair with leucocyte- and platelet-rich fibrin (L-PRF) results in better clinical and radiographic outcome at 12 months of follow-up than without L-PRF. Thirty-five patients were randomized to receive arthroscopic rotator cuff repair with L-PRF locally applied to the repair site (L-PRF+ group, n = 17) or without L-PRF (L-PRF- group, n = 18). Preoperative and postoperative clinical evaluation included the Subjective Shoulder Value, visual analog score for pain, Simple Shoulder Test, and Constant-Murley score. The anatomic watertight healing, tendon thickness, and tendon quality was evaluated using magnetic resonance arthrography at 12 months of follow-up. No complications were reported in either group. The mean Subjective Shoulder Value, Simple Shoulder Test, and Constant-Murley scores increased from preoperatively to postoperatively, showing no significant differences between the groups. Complete anatomic watertight healing was found in 11 of 17 in the L-PRF+ group and in 11 of 18 in the L-PRP- group (P = .73). The mean postoperative defect size (214 ± 130 mm(2) in the L-PRF+ group vs 161 ± 149 mm(2) in the L-PRF- group; P = .391) and the mean postoperative tendon quality according to Sugaya (L-PRF+ group: 3.0 ± 1.4, L-PRF- group: 3.0 ± 0.9) were similar in both groups at 12 months of follow-up. Arthroscopic rotator cuff repair with application of L-PRF yields no beneficial effect in clinical outcome, anatomic healing rate, mean postoperative defect size, and tendon quality at 12 months of follow-up. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Vection is the main contributor to motion sickness induced by visual yaw rotation: Implications for conflict and eye movement theories

PubMed Central

Pretto, Paolo; Oberfeld, Daniel; Hecht, Heiko; Bülthoff, Heinrich H.

2017-01-01

This study investigated the role of vection (i.e., a visually induced sense of self-motion), optokinetic nystagmus (OKN), and inadvertent head movements in visually induced motion sickness (VIMS), evoked by yaw rotation of the visual surround. These three elements have all been proposed as contributing factors in VIMS, as they can be linked to different motion sickness theories. However, a full understanding of the role of each factor is still lacking because independent manipulation has proven difficult in the past. We adopted an integrative approach to the problem by obtaining measures of potentially relevant parameters in four experimental conditions and subsequently combining them in a linear mixed regression model. To that end, participants were exposed to visual yaw rotation in four separate sessions. Using a full factorial design, the OKN was manipulated by a fixation target (present/absent), and vection strength by introducing a conflict in the motion direction of the central and peripheral field of view (present/absent). In all conditions, head movements were minimized as much as possible. Measured parameters included vection strength, vection variability, OKN slow phase velocity, OKN frequency, the number of inadvertent head movements, and inadvertent head tilt. Results show that VIMS increases with vection strength, but that this relation varies among participants (R2 = 0.48). Regression parameters for vection variability, head and eye movement parameters were not significant. These results may seem to be in line with the Sensory Conflict theory on motion sickness, but we argue that a more detailed definition of the exact nature of the conflict is required to fully appreciate the relationship between vection and VIMS. PMID:28380077

Real-time tracking of objects for a KC-135 microgravity experiment

NASA Technical Reports Server (NTRS)

Littlefield, Mark L.

1994-01-01

The design of a visual tracking system for use on the Extra-Vehicular Activity Helper/Retriever (EVAHR) is discussed. EVAHR is an autonomous robot designed to perform numerous tasks in an orbital microgravity environment. Since the ability to grasp a freely translating and rotating object is vital to the robot's mission, the EVAHR must analyze range image generated by the primary sensor. This allows EVAHR to locate and focus its sensors so that an accurate set of object poses can be determined and a grasp strategy planned. To test the visual tracking system being developed, a mathematical simulation was used to model the space station environment and maintain dynamics on the EVAHR and any other free floating objects. A second phase of the investigation consists of a series of experiments carried out aboard a KC-135 aircraft flying a parabolic trajectory to simulate microgravity.

Three dimensional fabric evolution of sheared sand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hasan, Alsidqi; Alshibli, Khalid

2012-10-24

Granular particles undergo translation and rolling when they are sheared. This paper presents a three-dimensional (3D) experimental assessment of fabric evolution of sheared sand at the particle level. F-75 Ottawa sand specimen was tested under an axisymmetric triaxial loading condition. It measured 9.5 mm in diameter and 20 mm in height. The quantitative evaluation was conducted by analyzing 3D high-resolution x-ray synchrotron micro-tomography images of the specimen at eight axial strain levels. The analyses included visualization of particle translation and rotation, and quantification of fabric orientation as shearing continued. Representative individual particles were successfully tracked and visualized to assess themore » mode of interaction between them. This paper discusses fabric evolution and compares the evolution of particles within and outside the shear band as shearing continues. Changes in particle orientation distributions are presented using fabric histograms and fabric tensor.« less

Development of a Mechanical Scanning Device With High-Frequency Ultrasound Transducer for Ultrasonic Capsule Endoscopy.

PubMed

Wang, Xingying; Seetohul, Vipin; Chen, Ruimin; Zhang, Zhiqiang; Qian, Ming; Shi, Zhehao; Yang, Ge; Mu, Peitian; Wang, Congzhi; Huang, Zhihong; Zhou, Qifa; Zheng, Hairong; Cochran, Sandy; Qiu, Weibao

2017-09-01

Wireless capsule endoscopy has opened a new era by enabling remote diagnostic assessment of the gastrointestinal tract in a painless procedure. Video capsule endoscopy is currently commercially available worldwide. However, it is limited to visualization of superficial tissue. Ultrasound (US) imaging is a complementary solution as it is capable of acquiring transmural information from the tissue wall. This paper presents a mechanical scanning device incorporating a high-frequency transducer specifically as a proof of concept for US capsule endoscopy (USCE), providing information that may usefully assist future research. A rotary solenoid-coil-based motor was employed to rotate the US transducer with sectional electronic control. A set of gears was used to convert the sectional rotation to circular rotation. A single-element focused US transducer with 39-MHz center frequency was used for high-resolution US imaging, connected to an imaging platform for pulse generation and image processing. Key parameters of US imaging for USCE applications were evaluated. Wire phantom imaging and tissue phantom imaging have been conducted to evaluate the performance of the proposed method. A porcine small intestine specimen was also used for imaging evaluation in vitro. Test results demonstrate that the proposed device and rotation mechanism are able to offer good image resolution ( [Formula: see text]) of the lumen wall, and they, therefore, offer a viable basis for the fabrication of a USCE device.

Dynamic Visual Acuity: a Functionally Relevant Research Tool

NASA Technical Reports Server (NTRS)

Peters, Brian T.; Brady, Rachel A.; Miller, Chris A.; Mulavara, Ajitkumar P.; Wood, Scott J.; Cohen, Helen S.; Bloomberg, Jacob J.

2010-01-01

Coordinated movements between the eyes and head are required to maintain a stable retinal image during head and body motion. The vestibulo-ocular reflex (VOR) plays a significant role in this gaze control system that functions well for most daily activities. However, certain environmental conditions or interruptions in normal VOR function can lead to inadequate ocular compensation, resulting in oscillopsia, or blurred vision. It is therefore possible to use acuity to determine when the environmental conditions, VOR function, or the combination of the two is not conductive for maintaining clear vision. Over several years we have designed and tested several tests of dynamic visual acuity (DVA). Early tests used the difference between standing and walking acuity to assess decrements in the gaze stabilization system after spaceflight. Supporting ground-based studies measured the responses from patients with bilateral vestibular dysfunction and explored the effects of visual target viewing distance and gait cycle events on walking acuity. Results from these studies show that DVA is affected by spaceflight, is degraded in patients with vestibular dysfunction, changes with target distance, and is not consistent across the gait cycle. We have recently expanded our research to include studies in which seated subjects are translated or rotated passively. Preliminary results from this work indicate that gaze stabilization ability may differ between similar active and passive conditions, may change with age, and can be affected by the location of the visual target with respect to the axis of motion. Use of DVA as a diagnostic tool is becoming more popular but the functional nature of the acuity outcome measure also makes it ideal for identifying conditions that could lead to degraded vision. By doing so, steps can be taken to alter the problematic environments to improve the man-machine interface and optimize performance.

Early Development of Object Unity: Evidence for Perceptual Completion in Newborns

ERIC Educational Resources Information Center

Valenza, Eloisa; Bulf, Hermann

2011-01-01

The present study aimed to investigate whether perceptual completion is available at birth, in the absence of any visual experience. An extremely underspecified kinetic visual display composed of four spatially separated fragments arranged to give rise to an illusory rectangle that occluded a vertical rod (illusory condition) or rotated so as not…

Visual management system and timber management application

Treesearch

Warren R. Bacon; Asa D. (Bud) Twombly

1979-01-01

This paper includes an illustration of a planning process to guide vegetation management throughout a travel route seen area and over the time period of a total management rotation (100-300 years). The process will produce direction on visual characteristics to be created and maintained within the biological potential and coordinated with associated re-source...

PREVIEW: Computer Assistance for Visual Management of Forested Landscapes

Treesearch

Erik Myklestad; J. Alan Wagar

1976-01-01

The PREVIEW computer program facilitates visual management of forested landscapes by generating perspective drawings that show proposed timber harvesting and regrowth throughout a rotation. Drawings show how changes would appear from selected viewing points and show landscapes as either a grid of distorted squares or by symbols representing trees, clearings, water,...

Integrating a Motion Base into a CAVE Automatic Virtual Environment: Phase 1

DTIC Science & Technology

2001-07-01

this, a CAVE system must perform well in the following motion-related areas: visual gaze stability, simulator sickness, realism (or face validity...and performance validity. Visual Gaze Stability Visual gaze stability, the ability to maintain eye fixation on a particular target, depends upon human...reflexes such as the vestibulo-ocular reflex (VOR) and the optokinetic nystagmus (OKN). VOR is a reflex that counter-rotates the eye relative to the

From Vesalius to virtual reality: How embodied cognition facilitates the visualization of anatomy

NASA Astrophysics Data System (ADS)

Jang, Susan

This study examines the facilitative effects of embodiment of a complex internal anatomical structure through three-dimensional ("3-D") interactivity in a virtual reality ("VR") program. Since Shepard and Metzler's influential 1971 study, it has been known that 3-D objects (e.g., multiple-armed cube or external body parts) are visually and motorically embodied in our minds. For example, people take longer to rotate mentally an image of their hand not only when there is a greater degree of rotation, but also when the images are presented in a manner incompatible with their natural body movement (Parsons, 1987a, 1994; Cooper & Shepard, 1975; Sekiyama, 1983). Such findings confirm the notion that our mental images and rotations of those images are in fact confined by the laws of physics and biomechanics, because we perceive, think and reason in an embodied fashion. With the advancement of new technologies, virtual reality programs for medical education now enable users to interact directly in a 3-D environment with internal anatomical structures. Given that such structures are not readily viewable to users and thus not previously susceptible to embodiment, coupled with the VR environment also affording all possible degrees of rotation, how people learn from these programs raises new questions. If we embody external anatomical parts we can see, such as our hands and feet, can we embody internal anatomical parts we cannot see? Does manipulating the anatomical part in virtual space facilitate the user's embodiment of that structure and therefore the ability to visualize the structure mentally? Medical students grouped in yoked-pairs were tasked with mastering the spatial configuration of an internal anatomical structure; only one group was allowed to manipulate the images of this anatomical structure in a 3-D VR environment, whereas the other group could only view the manipulation. The manipulation group outperformed the visual group, suggesting that the interactivity that took place among the manipulation group promoted visual and motoric embodiment, which in turn enhanced learning. Moreover, when accounting for spatial ability, it was found that manipulation benefits students with low spatial ability more than students with high spatial ability.

A Reevaluation of the Vestibulo-Ocular Reflex: New Ideas of its Purpose, Properties, Neural Substrate, and Disorders

NASA Technical Reports Server (NTRS)

Leigh, R. John; Brandt, Thomas

1992-01-01

Conventional views of the Vestibulo-Ocular Reflex (VOR) have emphasized testing with caloric stimuli and by passively rotating patients at low frequencies in a chair. The properties of the VOR tested under these conditions differ from the performance of this reflex during the natural function for which it evolved-locomotion. Only the VOR (and not visually mediated eye movements) can cope with the high-frequency angular and linear perturbations of the head that occur during locomotion; this is achieved by generating eye movements at short latency (less than 16 msec). Interpretation of vestibular testing is enhanced by the realization that, although the di- and trisynaptic components of the VOR are essential for this short-latency response, the overall accuracy and plasticity of the VOR depend upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously encode inputs from the labyrinthine semicircular canals and otoliths, as well as from the visual and somatosensory systems. The central vestibular pathways branch to contact vestibular cortex (for perception) and the spinal cord (for control of posture). Thus, the vestibular nuclei basically coordinate the stabilization of gaze and posture, and contribute to the perception of verticality and self-motion. Consequently, brainstem disorders that disrupt the VOR cause not just only nystagmus, but also instability of posture (eg, increased fore-aft sway in patients with downbeat nystagmus) and disturbance of spatial orientation (eg, tilt of the subjective visual vertical in Wallenberg's syndrome).

Is visual image segmentation a bottom-up or an interactive process?

PubMed

Vecera, S P; Farah, M J

1997-11-01

Visual image segmentation is the process by which the visual system groups features that are part of a single shape. Is image segmentation a bottom-up or an interactive process? In Experiments 1 and 2, we presented subjects with two overlapping shapes and asked them to determine whether two probed locations were on the same shape or on different shapes. The availability of top-down support was manipulated by presenting either upright or rotated letters. Subjects were fastest to respond when the shapes corresponded to familiar shapes--the upright letters. In Experiment 3, we used a variant of this segmentation task to rule out the possibility that subjects performed same/different judgments after segmentation and recognition of both letters. Finally, in Experiment 4, we ruled out the possibility that the advantage for upright letters was merely due to faster recognition of upright letters relative to rotated letters. The results suggested that the previous effects were not due to faster recognition of upright letters; stimulus familiarity influenced segmentation per se. The results are discussed in terms of an interactive model of visual image segmentation.

Vestibular signals in macaque extrastriate visual cortex are functionally appropriate for heading perception

PubMed Central

Liu, Sheng; Angelaki, Dora E.

2009-01-01

Visual and vestibular signals converge onto the dorsal medial superior temporal area (MSTd) of the macaque extrastriate visual cortex, which is thought to be involved in multisensory heading perception for spatial navigation. Peripheral otolith information, however, is ambiguous and cannot distinguish linear accelerations experienced during self-motion from those due to changes in spatial orientation relative to gravity. Here we show that, unlike peripheral vestibular sensors but similar to lobules 9 and 10 of the cerebellar vermis (nodulus and uvula), MSTd neurons respond selectively to heading and not to changes in orientation relative to gravity. In support of a role in heading perception, MSTd vestibular responses are also dominated by velocity-like temporal dynamics, which might optimize sensory integration with visual motion information. Unlike the cerebellar vermis, however, MSTd neurons also carry a spatial orientation-independent rotation signal from the semicircular canals, which could be useful in compensating for the effects of head rotation on the processing of optic flow. These findings show that vestibular signals in MSTd are appropriately processed to support a functional role in multisensory heading perception. PMID:19605631

Intercepting a sound without vision

PubMed Central

Vercillo, Tiziana; Tonelli, Alessia; Gori, Monica

2017-01-01

Visual information is extremely important to generate internal spatial representations. In the auditory modality, the absence of visual cues during early infancy does not preclude the development of some spatial strategies. However, specific spatial abilities might result impaired. In the current study, we investigated the effect of early visual deprivation on the ability to localize static and moving auditory stimuli by comparing sighted and early blind individuals’ performance in different spatial tasks. We also examined perceptual stability in the two groups of participants by matching localization accuracy in a static and a dynamic head condition that involved rotational head movements. Sighted participants accurately localized static and moving sounds. Their localization ability remained unchanged after rotational movements of the head. Conversely, blind participants showed a leftward bias during the localization of static sounds and a little bias for moving sounds. Moreover, head movements induced a significant bias in the direction of head motion during the localization of moving sounds. These results suggest that internal spatial representations might be body-centered in blind individuals and that in sighted people the availability of visual cues during early infancy may affect sensory-motor interactions. PMID:28481939

Trunk-rotation flexibility in collegiate softball players with or without a history of shoulder or elbow injury.

PubMed

Aragon, Veronica J; Oyama, Sakiko; Oliaro, Scott M; Padua, Darin A; Myers, Joseph B

2012-01-01

Throwing is a whole-body motion that requires the transfer of momentum from the lower extremity to the upper extremity via the trunk. No research to date examines the association between a history of shoulder or elbow injury and trunk flexibility in overhead athletes. To determine if injury history and trunk-rotation flexibility are associated and to compare trunk-rotation flexibility measured using 3 clinical tests: half-kneeling rotation test with the bar in the back, half-kneeling rotation test with the bar in the front, and seated rotation test in softball position players with or without a history of shoulder or elbow injury. Cross-sectional design. University softball facilities. Sixty-five female National Collegiate Athletic Association Division I softball position players. Trunk-rotation flexibility was measured with 3 clinical tests. Recent injury history was obtained using a questionnaire and verified by the certified athletic trainer. Binomial regression models were used to determine if injury history was associated with flexibility categories (high, normal, or limited tertiles) for each of the 6 (3 tests × 2 directions) trunk-rotation flexibility measures. Trunk-rotation flexibility measures from 3 clinical tests were compared between participants with and without a history of shoulder or elbow injury using analysis-of-variance models. When measured using the half-kneeling rotation test with the bar in the back and the seated rotation test, injury history and forward trunk-rotation flexibility were associated. However, no mean group differences were seen in trunk-rotation flexibility between participants with and without a history of shoulder or elbow injury. Limited forward trunk-rotation flexibility may be a risk factor for shoulder or elbow injuries. However, further study is needed to confirm the study finding.

Errors of car wheels rotation rate measurement using roller follower on test benches

NASA Astrophysics Data System (ADS)

Potapov, A. S.; Svirbutovich, O. A.; Krivtsov, S. N.

2018-03-01

The article deals with rotation rate measurement errors, which depend on the motor vehicle rate, on the roller, test benches. Monitoring of the vehicle performance under operating conditions is performed on roller test benches. Roller test benches are not flawless. They have some drawbacks affecting the accuracy of vehicle performance monitoring. Increase in basic velocity of the vehicle requires increase in accuracy of wheel rotation rate monitoring. It determines the degree of accuracy of mode identification for a wheel of the tested vehicle. To ensure measurement accuracy for rotation velocity of rollers is not an issue. The problem arises when measuring rotation velocity of a car wheel. The higher the rotation velocity of the wheel is, the lower the accuracy of measurement is. At present, wheel rotation frequency monitoring on roller test benches is carried out by following-up systems. Their sensors are rollers following wheel rotation. The rollers of the system are not kinematically linked to supporting rollers of the test bench. The roller follower is forced against the wheels of the tested vehicle by means of a spring-lever mechanism. Experience of the test bench equipment operation has shown that measurement accuracy is satisfactory at small rates of vehicles diagnosed on roller test benches. With a rising diagnostics rate, rotation velocity measurement errors occur in both braking and pulling modes because a roller spins about a tire tread. The paper shows oscillograms of changes in wheel rotation velocity and rotation velocity measurement system’s signals when testing a vehicle on roller test benches at specified rates.

Axial tomography in 3D live cell microscopy

NASA Astrophysics Data System (ADS)

Richter, Verena; Bruns, Sarah; Bruns, Thomas; Piper, Mathis; Weber, Petra; Wagner, Michael; Cremer, Christoph; Schneckenburger, Herbert

2017-07-01

A miniaturized setup for sample rotation on a microscope stage has been developed, combined with light sheet, confocal or structured illumination microscopy and applied to living cells as well as to small organisms. This setup permits axial tomography with improved visualization of single cells or small cell clusters as well as an enhanced effective 3D resolution upon sample rotation.

Three-Dimensional Visualization of Wave Functions for Rotating Molecule: Plot of Spherical Harmonics

ERIC Educational Resources Information Center

Nagaoka, Shin-ichi; Teramae, Hiroyuki; Nagashima, Umpei

2013-01-01

At an early stage of learning quantum chemistry, undergraduate students usually encounter the concepts of the particle in a box, the harmonic oscillator, and then the particle on a sphere. Rotational levels of a diatomic molecule can be well approximated by the energy levels of the particle on a sphere. Wave functions for the particle in a…

Visualization of a vortex flow in a rotating tank

NASA Astrophysics Data System (ADS)

Kawano, Yosuke

Flow structures of a vortex in a rotating tank were studied employing tracer method. The velocity measurements were made by photographing the motions of small polystyrene particles and analyzing strobo flash light pictures. The vortex flow is confined to a cylindrical region which is composed of a spiral upward flow in the center surrounded by an annular downward flow.

A model for size- and rotation-invariant pattern processing in the visual system.

PubMed

Reitboeck, H J; Altmann, J

1984-01-01

The mapping of retinal space onto the striate cortex of some mammals can be approximated by a log-polar function. It has been proposed that this mapping is of functional importance for scale- and rotation-invariant pattern recognition in the visual system. An exact log-polar transform converts centered scaling and rotation into translations. A subsequent translation-invariant transform, such as the absolute value of the Fourier transform, thus generates overall size- and rotation-invariance. In our model, the translation-invariance is realized via the R-transform. This transform can be executed by simple neural networks, and it does not require the complex computations of the Fourier transform, used in Mellin-transform size-invariance models. The logarithmic space distortion and differentiation in the first processing stage of the model is realized via "Mexican hat" filters whose diameter increases linearly with eccentricity, similar to the characteristics of the receptive fields of retinal ganglion cells. Except for some special cases, the model can explain object recognition independent of size, orientation and position. Some general problems of Mellin-type size-invariance models-that also apply to our model-are discussed.

Helicopter Flight Simulation Motion Platform Requirements

NASA Technical Reports Server (NTRS)

Schroeder, Jeffery Allyn

1999-01-01

To determine motion fidelity requirements, a series of piloted simulations was performed. Several key results were found. First, lateral and vertical translational platform cues had significant effects on fidelity. Their presence improved performance and reduced pilot workload. Second, yaw and roll rotational platform cues were not as important as the translational platform cues. In particular, the yaw rotational motion platform cue did not appear at all useful in improving performance or reducing workload. Third, when the lateral translational platform cue was combined with visual yaw rotational cues, pilots believed the platform was rotating when it was not. Thus, simulator systems can be made more efficient by proper combination of platform and visual cues. Fourth, motion fidelity specifications were revised that now provide simulator users with a better prediction of motion fidelity based upon the frequency responses of their motion control laws. Fifth, vertical platform motion affected pilot estimates of steady-state altitude during altitude repositioning. Finally, the combined results led to a general method for configuring helicopter motion systems and for developing simulator tasks that more likely represent actual flight. The overall results can serve as a guide to future simulator designers and to today's operators.

BONA FIDE, STRONG-VARIABLE GALACTIC LUMINOUS BLUE VARIABLE STARS ARE FAST ROTATORS: DETECTION OF A HIGH ROTATIONAL VELOCITY IN HR CARINAE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Groh, J. H.; Damineli, A.; Moises, A. P.

2009-11-01

We report optical observations of the luminous blue variable (LBV) HR Carinae which show that the star has reached a visual minimum phase in 2009. More importantly, we detected absorptions due to Si IV lambdalambda4088-4116. To match their observed line profiles from 2009 May, a high rotational velocity of v{sub rot} approx = 150 +- 20 km s{sup -1} is needed (assuming an inclination angle of 30 deg.), implying that HR Car rotates at approx =0.88 +- 0.2 of its critical velocity for breakup (v{sub crit}). Our results suggest that fast rotation is typical in all strong-variable, bona fide galacticmore » LBVs, which present S-Dor-type variability. Strong-variable LBVs are located in a well-defined region of the HR diagram during visual minimum (the 'LBV minimum instability strip'). We suggest this region corresponds to where v{sub crit} is reached. To the left of this strip, a forbidden zone with v{sub rot}/v{sub crit}>1 is present, explaining why no LBVs are detected in this zone. Since dormant/ex LBVs like P Cygni and HD 168625 have low v{sub rot}, we propose that LBVs can be separated into two groups: fast-rotating, strong-variable stars showing S-Dor cycles (such as AG Car and HR Car) and slow-rotating stars with much less variability (such as P Cygni and HD 168625). We speculate that supernova (SN) progenitors which had S-Dor cycles before exploding (such as in SN 2001ig, SN 2003bg, and SN 2005gj) could have been fast rotators. We suggest that the potential difficulty of fast-rotating Galactic LBVs to lose angular momentum is additional evidence that such stars could explode during the LBV phase.« less

Evaluation of a web-based asynchronous pediatric emergency medicine learning tool for residents and medical students.

PubMed

Burnette, Kreg; Ramundo, Maria; Stevenson, Michelle; Beeson, Michael S

2009-12-01

To examine the effectiveness of an asynchronous learning tool consisting of web-based lectures for trainees covering major topics pertinent to pediatric emergency medicine (PEM) and to assess resident and student evaluation of this mode of education. PEM faculty and fellows created a 21-lecture, web-based curriculum. These 20-minute online lectures used Microsoft PowerPoint with the voice-over feature. A 75-question test was created to assess the effectiveness of the web-based learning model, administered online before and after the rotation in the pediatric emergency department (PED). All fourth-year medical students and residents (across all specialties) rotating through the PED were required to complete 10 of the 21 lectures during their 1-month rotation. The main outcome variable was difference in score between pre- and post-rotation tests of participants who viewed no lectures and those who viewed at least one lecture. Evaluation of the program was assessed by anonymous survey using 5-point discrete visual analog scales. Responses of 4 or 5 were considered positive for analysis. One hundred eleven residents and fourth-year medical students participated in the program. An initial 32 completed testing before implementation of the on-line lectures (March 2007-August 2007), and another five did not complete the on-line lectures after implementation (September 2007-February 2008). Seventy-one completed testing and on-line lectures, and all but three completed at least 10 on-line lectures during their rotation. Fourteen of 111 trainees did not complete the pre- or post-test (including two who viewed the lectures). The mean change in score was a 1% improvement from pre-test to post-test for trainees who viewed no lectures and a 6.2% improvement for those who viewed the lectures (mean difference = 5.2%, 95% confidence interval = 2.5% to 7.9%). In the linear regression model, the estimate of the coefficient was 0.43 (p < 0.001), meaning that, for each lecture viewed, post-test score rose by 0.43%. Sixty-nine of 75 test items (92%) had a point biserial correlation greater than 0.15. Thirty of the 72 trainees who completed the online lectures and testing (42%) returned surveys. All were comfortable using the Internet, and 87% (26/30) found the web-site easy to use. All felt that their educational goals were met, and 100% felt that the format would be useful in other areas of education. Although not a replacement for traditional bedside teaching, the use of web-based lectures as an asynchronous learning tool has a positive effect on medical knowledge test scores. Trainees were able to view online lectures on their own schedules, in the location of their choice. This is helpful in a field with shift work, in which trainees rarely work together, making it difficult to synchronously provide lectures to all trainees. (c) 2009 by the Society for Academic Emergency Medicine.

Integration of visual and non-visual self-motion cues during voluntary head movements in the human brain.

PubMed

Schindler, Andreas; Bartels, Andreas

2018-05-15

Our phenomenological experience of the stable world is maintained by continuous integration of visual self-motion with extra-retinal signals. However, due to conventional constraints of fMRI acquisition in humans, neural responses to visuo-vestibular integration have only been studied using artificial stimuli, in the absence of voluntary head-motion. We here circumvented these limitations and let participants to move their heads during scanning. The slow dynamics of the BOLD signal allowed us to acquire neural signal related to head motion after the observer's head was stabilized by inflatable aircushions. Visual stimuli were presented on head-fixed display goggles and updated in real time as a function of head-motion that was tracked using an external camera. Two conditions simulated forward translation of the participant. During physical head rotation, the congruent condition simulated a stable world, whereas the incongruent condition added arbitrary lateral motion. Importantly, both conditions were precisely matched in visual properties and head-rotation. By comparing congruent with incongruent conditions we found evidence consistent with the multi-modal integration of visual cues with head motion into a coherent "stable world" percept in the parietal operculum and in an anterior part of parieto-insular cortex (aPIC). In the visual motion network, human regions MST, a dorsal part of VIP, the cingulate sulcus visual area (CSv) and a region in precuneus (Pc) showed differential responses to the same contrast. The results demonstrate for the first time neural multimodal interactions between precisely matched congruent versus incongruent visual and non-visual cues during physical head-movement in the human brain. The methodological approach opens the path to a new class of fMRI studies with unprecedented temporal and spatial control over visuo-vestibular stimulation. Copyright © 2018 Elsevier Inc. All rights reserved.

The presence and influence of posterior capsule tightness on different shoulder problems.

PubMed

Duzgun, Irem; Turgut, Elif; Çinar-Medeni, Özge; Kafa, Nihan; Tuna, Zeynep; Elbasan, Bulent; Oskay, Deran

2017-01-01

In the literature it has been shown that posterior capsule flexibility is a precursor to shoulder problems. However, no study thus far has shown the influence of the flexibility of posterior capsule in different shoulder pathologies. This study set about to compare the role of posterior capsule tightness in different shoulder problems. One-hundred-twenty-five patients diagnosed with shoulder subacromial impingement syndrome (n= 52), partial rotator cuff tear (n= 31) or frozen shoulder (n= 42) and 30 asymptomatic peers participated in the study. Horizontal adduction was assessed in side-lying position for posterior capsule tightness. Pain was measured via the visual analogue scale and shoulder range of motion and active total elevation was assessed with goniometer. Hand behind the back (HBB) test was assessed the active internal rotation by measuring the distance between T5 and the thumb. It was found that the affected side of the posterior capsules of the patients with subacromial impingement syndrome (p< 0.001), partial rotator cuff tear (p< 0.001) and frozen shoulder (p< 0.001) was stiffer than their healthy side. There were significant differences among groups in the level of tightness in the posterior capsule between the affected and the healthy sides (p< 0.001). All range of motion of the shoulder including HBB test and the posterior capsule tightness of the affected side are found to be correlated (p< 0.05). This study emphasized that the posterior capsule's susceptibility to tightness is most evident in frozen shoulder among different shoulder problems.

Garnet film rotator applied in polarizing microscope for domain image modulation (abstract)

NASA Astrophysics Data System (ADS)

Wakabayashi, K.; Numata, T.; Inokuchi, S.

1991-04-01

A garnet film polarization rotator placed before the analyzer in a polarizing microscope was investigated to obtain the difference image of a positive and a negative one of magnetic domain in real time along with an image processor. In the difference image, a nonmagnetic image can be reduced and hence the weak magnetic contrast enhanced. Theoretical calculation of S/N and contrast C of the domain image as a function of the rotation shows they take maxima at the rotation angle of 2.6° and 0.1°, respectively, with the extinction ratio of e=4×10-6 of a polarizing microscope. Thus, since the thickness of the garnet film required is 1 μm or so, the absorption by the garnet rotator does not bring a serious problem even in a visible region for the domain observation. The optimum rotation of the rotator for a high quality observation was obtained by a quantitative study of images obtained experimentally as well as by a visual evaluation. A magnetically unsaturated garnet film with perpendicular magnetization (i.e., multidomain) was employed as a rotator, in which the polarization rotation angle θm of the undeflected beam with respect to the light diffraction could be continuously varied by an applied magnetic field. The dependences of S/N and C on θm were measured, resulting in a well agreement between the measured and the calculated. The visually best image was obtained at θm=0.5° which made the product of S/N and C maximum. The domain image of the Kerr rotation angle of θk=0.22° was observed in S/N=47 dB and C=0.4 when Ar+ laser (λ=515 nm) of tenths of a watt was employed as a light source. Since the domain image with 47 dB S/N does not need an image summation for a noise reduction, a garnet film rotator makes it possible to invert the contrast of a domain image in a real time for an improved domain observation.

Moving visual scenes influence the apparent direction of gravity.

NASA Technical Reports Server (NTRS)

Dichgans, J.; Held, R.; Young, L. R.; Brandt, T.

1972-01-01

It is shown that an observer viewing a wide-angled display rotating about its line of sight develops a feeling that his body is tilted and has the illusion that a vertical straight edge is tilted in a direction opposite to that of rotation. Experiments on subjects who monocularly viewed rotating disks with various settings within restricted fields of view are described to substantiate these findings. Displacement of the perceived vertical increased to a maximum of average 15 deg when the stimulus speed increased to 30 deg per sec.

The development of interactive online learning tools for the study of anatomy.

PubMed

O'Byrne, Patrick J; Patry, Anne; Carnegie, Jacqueline A

2008-01-01

The study of human anatomy is a core component of health science programs. However large student enrolments and the content-packed curricula associated with these programs have made it difficult for students to have regular access to cadaver laboratories. Adobe Flash MXwas used with cadaver digital photographs and textbook-derived illustrations to develop interactive anatomy images that were made available to undergraduate health science students enrolled in first-year combined anatomy and physiology (ANP) courses at the University of Ottawa. Colour coding was used to direct student attention, facilitate name-structure association, improve visualization of structure contours, assist students in the construction of anatomical pathways, and to reinforce functional or anatomical groupings. The ability of two-dimensional media to support the visualization of three-dimensional structure was extended by developing the fade-through image (students use a sliding bar to move through tissues) as well as the rotating image in which entire organs such as the skull were photographed at eight angles of rotation. Finally, students were provided with interactive exercises that they could repeatedly try to obtain immediate feedback regarding their learning progress. Survey data revealed that the learning and self-testing tools were used widely and that students found them relevant and supportive of their self-learning. Interestingly, student summative examination outcomes did not differ between those students who had access to the online tools and a corresponding student group from the previous academic year who did not. Interactive learning tools can be tailored to meet program-specific learning objectives as a cost-effective means of facilitating the study of human anatomy. Virtual interactive anatomy exercises provide learning opportunities for students outside the lecture room that are of especial value to visual and kinesthetic learners.

A reference Pelton turbine - High speed visualization in the rotating frame

NASA Astrophysics Data System (ADS)

Solemslie, Bjørn W.; Dahlhaug, Ole G.

2016-11-01

To enable a detailed study the flow mechanisms effecting the flow within the reference Pelton runner designed at the Waterpower Laboratory (NTNLT) a flow visualization system has been developed. The system enables high speed filming of the hydraulic surface of a single bucket in the rotating frame of reference. It is built with an angular borescopes adapter entering the turbine along the rotational axis and a borescope embedded within a bucket. A stationary high speed camera located outside the turbine housing has been connected to the optical arrangement by a non-contact coupling. The view point of the system includes the whole hydraulic surface of one half of a bucket. The system has been designed to minimize the amount of vibrations and to ensure that the vibrations felt by the borescope are the same as those affecting the camera. The preliminary results captured with the system are promising and enable a detailed study of the flow within the turbine.

Organized motions in a jet in crossflow

NASA Astrophysics Data System (ADS)

Rivero, A.; Ferré, J. A.; Giralt, Francesc

2001-10-01

An experimental study to identify the structures present in a jet in crossflow has been carried out at a jet-to-crossflow velocity ratio U/Ucf = 3.8 and Reynolds number Re = UcfD/v = 6600. The hot-wire velocity data measured with a rake of eight X-wires at x/D = 5 and 15 and flow visualizations using planar laser-induced fluorescence (PLIF) confirm that the well-established pair of counter-rotating vortices is a feature of the mean field and that the upright, tornado-like or Fric's vortices that are shed to the leeward side of the jet are connected to the jet flow at the core. The counter-rotating vortex pair is strongly modulated by a coherent velocity field that, in fact, is as important as the mean velocity field. Three different structures folded vortex rings, horseshoe vortices and handle-type structures contribute to this coherent field. The new handle-like structures identified in the current study link the boundary layer vorticity with the counter-rotating vortex pair through the upright tornado-like vortices. They are responsible for the modulation and meandering of the counter-rotating vortex pair observed both in video recordings of visualizations and in the instantaneous velocity field. These results corroborate that the genesis of the dominant counter-rotating vortex pair strongly depends on the high pressure gradients that develop in the region near the jet exit, both inside and outside the nozzle.

Effects of local microwave diathermy on shoulder pain and function in patients with rotator cuff tendinopathy in comparison to subacromial corticosteroid injections: a single-blind randomized trial.

PubMed

Rabini, Alessia; Piazzini, Diana B; Bertolini, Carlo; Deriu, Laura; Saccomanno, Maristella F; Santagada, Domenico A; Sgadari, Antonio; Bernabei, Roberto; Fabbriciani, Carlo; Marzetti, Emanuele; Milano, Giuseppe

2012-04-01

Single-blind randomized clinical trial, with a follow-up of 24 weeks. To determine the effects of hyperthermia via localized microwave diathermy on pain and disability in comparison to subacromial corticosteroid injections in patients with rotator cuff tendinopathy. Hyperthermia improves symptoms and function in several painful musculoskeletal disorders. However, the effects of microwave diathermy in rotator cuff tendinopathy have not yet been established. Ninety-two patients with rotator cuff tendinopathy and pain lasting for at least 3 months were recruited from the outpatient clinic of the Department of Orthopaedics and Traumatology, University Hospital, Rome, Italy. Participants were randomly allocated to either local microwave diathermy or subacromial corticosteroids. The primary outcome measure was the short form of the Disabilities of the Arm, Shoulder and Hand Questionnaire (QuickDASH). Secondary outcome measures were the Constant-Murley shoulder outcome score and a visual analog scale for pain assessment. At the end of treatment and at follow-up, both treatment groups experienced improvements in all outcome measures relative to baseline values. Changes over time in QuickDASH, Constant-Murley, and visual analog scale scores were not different between treatment arms. In patients with rotator cuff tendinopathy, the effects of localized microwave diathermy on disability, shoulder function, and pain are equivalent to those elicited by subacromial corticosteroid injections.

Vestibular responses in the macaque pedunculopontine nucleus and central mesencephalic reticular formation.

PubMed

Aravamuthan, B R; Angelaki, D E

2012-10-25

The pedunculopontine nucleus (PPN) and central mesencephalic reticular formation (cMRF) both send projections and receive input from areas with known vestibular responses. Noting their connections with the basal ganglia, the locomotor disturbances that occur following lesions of the PPN or cMRF, and the encouraging results of PPN deep brain stimulation in Parkinson's disease patients, both the PPN and cMRF have been linked to motor control. In order to determine the existence of and characterize vestibular responses in the PPN and cMRF, we recorded single neurons from both structures during vertical and horizontal rotation, translation, and visual pursuit stimuli. The majority of PPN cells (72.5%) were vestibular-only (VO) cells that responded exclusively to rotation and translation stimuli but not visual pursuit. Visual pursuit responses were much more prevalent in the cMRF (57.1%) though close to half of cMRF cells were VO cells (41.1%). Directional preferences also differed between the PPN, which was preferentially modulated during nose-down pitch, and cMRF, which was preferentially modulated during ipsilateral yaw rotation. Finally, amplitude responses were similar between the PPN and cMRF during rotation and pursuit stimuli, but PPN responses to translation were of higher amplitude than cMRF responses. Taken together with their connections to the vestibular circuit, these results implicate the PPN and cMRF in the processing of vestibular stimuli and suggest important roles for both in responding to motion perturbations like falls and turns. Copyright © 2012 IBRO. Published by Elsevier Ltd. All rights reserved.

Separating "Rotators" from "Nonrotators" in the Mental Rotations Test: A Multigroup Latent Class Analysis

ERIC Educational Resources Information Center

Geiser, Christian; Lehmann, Wolfgang; Eid, Michael

2006-01-01

Items of mental rotation tests can not only be solved by mental rotation but also by other solution strategies. A multigroup latent class analysis of 24 items of the Mental Rotations Test (MRT) was conducted in a sample of 1,695 German pupils and students to find out how many solution strategies can be identified for the items of this test. The…

Evaluation of navigation interfaces in virtual environments

NASA Astrophysics Data System (ADS)

Mestre, Daniel R.

2014-02-01

When users are immersed in cave-like virtual reality systems, navigational interfaces have to be used when the size of the virtual environment becomes larger than the physical extent of the cave floor. However, using navigation interfaces, physically static users experience self-motion (visually-induced vection). As a consequence, sensorial incoherence between vision (indicating self-motion) and other proprioceptive inputs (indicating immobility) can make them feel dizzy and disoriented. We tested, in two experimental studies, different locomotion interfaces. The objective was twofold: testing spatial learning and cybersickness. In a first experiment, using first-person navigation with a flystick ®, we tested the effect of sensorial aids, a spatialized sound or guiding arrows on the ground, attracting the user toward the goal of the navigation task. Results revealed that sensorial aids tended to impact negatively spatial learning. Moreover, subjects reported significant levels of cybersickness. In a second experiment, we tested whether such negative effects could be due to poorly controlled rotational motion during simulated self-motion. Subjects used a gamepad, in which rotational and translational displacements were independently controlled by two joysticks. Furthermore, we tested first- versus third-person navigation. No significant difference was observed between these two conditions. Overall, cybersickness tended to be lower, as compared to experiment 1, but the difference was not significant. Future research should evaluate further the hypothesis of the role of passively perceived optical flow in cybersickness, but manipulating the virtual environment'sperrot structure. It also seems that video-gaming experience might be involved in the user's sensitivity to cybersickness.

Scientific Visualization of Radio Astronomy Data using Gesture Interaction

NASA Astrophysics Data System (ADS)

Mulumba, P.; Gain, J.; Marais, P.; Woudt, P.

2015-09-01

MeerKAT in South Africa (Meer = More Karoo Array Telescope) will require software to help visualize, interpret and interact with multidimensional data. While visualization of multi-dimensional data is a well explored topic, little work has been published on the design of intuitive interfaces to such systems. More specifically, the use of non-traditional interfaces (such as motion tracking and multi-touch) has not been widely investigated within the context of visualizing astronomy data. We hypothesize that a natural user interface would allow for easier data exploration which would in turn lead to certain kinds of visualizations (volumetric, multidimensional). To this end, we have developed a multi-platform scientific visualization system for FITS spectral data cubes using VTK (Visualization Toolkit) and a natural user interface to explore the interaction between a gesture input device and multidimensional data space. Our system supports visual transformations (translation, rotation and scaling) as well as sub-volume extraction and arbitrary slicing of 3D volumetric data. These tasks were implemented across three prototypes aimed at exploring different interaction strategies: standard (mouse/keyboard) interaction, volumetric gesture tracking (Leap Motion controller) and multi-touch interaction (multi-touch monitor). A Heuristic Evaluation revealed that the volumetric gesture tracking prototype shows great promise for interfacing with the depth component (z-axis) of 3D volumetric space across multiple transformations. However, this is limited by users needing to remember the required gestures. In comparison, the touch-based gesture navigation is typically more familiar to users as these gestures were engineered from standard multi-touch actions. Future work will address a complete usability test to evaluate and compare the different interaction modalities against the different visualization tasks.

Combined pitch and roll and cybersickness in a virtual environment.

PubMed

Bonato, Frederick; Bubka, Andrea; Palmisano, Stephen

2009-11-01

Stationary subjects who perceive visually induced illusions of self-motion, or vection, in virtual reality (VR) often experience cybersickness, the symptoms of which are similar to those experienced during motion sickness. An experiment was conducted to test the effects of single and dual-axis rotation of a virtual environment on cybersickness. It was predicted that VR displays which induced illusory dual-axis (as opposed to single-axis) self-rotations in stationary subjects would generate more sensory conflict and subsequently more cybersickness. There were 19 individuals (5 men, 14 women, mean age = 19.8 yr) who viewed the interior of a virtual cube that steadily rotated (at 60 degrees x s(-1)) about either the pitch axis or both the pitch and roll axes simultaneously. Subjects completed the Simulator Sickness Questionnaire (SSQ) before a trial and after 5 min of stimulus viewing. Post-treatment total SSQ scores and subscores for nausea, oculomotor, and disorientation were significantly higher in the dual-axis condition. These results support the hypothesis that a vection-inducing VR stimulus that rotates about two axes generates more cybersickness compared to aVR stimulus that rotates about only one. In the single-axis condition, sensory conflict and pseudo-Coriolis effects may have led to symptoms. However, in the dual-axis condition, not only was perceived self-motion more complex (two axes compared to one), the inducing stimulus was consistent with twice as much self-motion. Hence, the increased likelihood/magnitude of sensory conflict and pseudo-Coriolis effects may have subsequently resulted in a higher degree of cybersickness in the dual-axis condition.

Role of somatosensory and vestibular cues in attenuating visually induced human postural sway

NASA Technical Reports Server (NTRS)

Peterka, R. J.; Benolken, M. S.

1995-01-01

The purpose of this study was to determine the contribution of visual, vestibular, and somatosensory cues to the maintenance of stance in humans. Postural sway was induced by full-field, sinusoidal visual surround rotations about an axis at the level of the ankle joints. The influences of vestibular and somatosensory cues were characterized by comparing postural sway in normal and bilateral vestibular absent subjects in conditions that provided either accurate or inaccurate somatosensory orientation information. In normal subjects, the amplitude of visually induced sway reached a saturation level as stimulus amplitude increased. The saturation amplitude decreased with increasing stimulus frequency. No saturation phenomena were observed in subjects with vestibular loss, implying that vestibular cues were responsible for the saturation phenomenon. For visually induced sways below the saturation level, the stimulus-response curves for both normal subjects and subjects experiencing vestibular loss were nearly identical, implying (1) that normal subjects were not using vestibular information to attenuate their visually induced sway, possibly because sway was below a vestibular-related threshold level, and (2) that subjects with vestibular loss did not utilize visual cues to a greater extent than normal subjects; that is, a fundamental change in visual system "gain" was not used to compensate for a vestibular deficit. An unexpected finding was that the amplitude of body sway induced by visual surround motion could be almost 3 times greater than the amplitude of the visual stimulus in normal subjects and subjects with vestibular loss. This occurred in conditions where somatosensory cues were inaccurate and at low stimulus amplitudes. A control system model of visually induced postural sway was developed to explain this finding. For both subject groups, the amplitude of visually induced sway was smaller by a factor of about 4 in tests where somatosensory cues provided accurate versus inaccurate orientation information. This implied (1) that the subjects experiencing vestibular loss did not utilize somatosensory cues to a greater extent than normal subjects; that is, changes in somatosensory system "gain" were not used to compensate for a vestibular deficit, and (2) that the threshold for the use of vestibular cues in normal subjects was apparently lower in test conditions where somatosensory cues were providing accurate orientation information.

Evaluation of the Risk Factors for a Rotator Cuff Retear After Repair Surgery.

PubMed

Lee, Yeong Seok; Jeong, Jeung Yeol; Park, Chan-Deok; Kang, Seung Gyoon; Yoo, Jae Chul

2017-07-01

A retear is a significant clinical problem after rotator cuff repair. However, no study has evaluated the retear rate with regard to the extent of footprint coverage. To evaluate the preoperative and intraoperative factors for a retear after rotator cuff repair, and to confirm the relationship with the extent of footprint coverage. Cohort study; Level of evidence, 3. Data were retrospectively collected from 693 patients who underwent arthroscopic rotator cuff repair between January 2006 and December 2014. All repairs were classified into 4 types of completeness of repair according to the amount of footprint coverage at the end of surgery. All patients underwent magnetic resonance imaging (MRI) after a mean postoperative duration of 5.4 months. Preoperative demographic data, functional scores, range of motion, and global fatty degeneration on preoperative MRI and intraoperative variables including the tear size, completeness of rotator cuff repair, concomitant subscapularis repair, number of suture anchors used, repair technique (single-row or transosseous-equivalent double-row repair), and surgical duration were evaluated. Furthermore, the factors associated with failure using the single-row technique and transosseous-equivalent double-row technique were analyzed separately. The retear rate was 7.22%. Univariate analysis revealed that rotator cuff retears were affected by age; the presence of inflammatory arthritis; the completeness of rotator cuff repair; the initial tear size; the number of suture anchors; mean operative time; functional visual analog scale scores; Simple Shoulder Test findings; American Shoulder and Elbow Surgeons scores; and fatty degeneration of the supraspinatus, infraspinatus, and subscapularis. Multivariate logistic regression analysis revealed patient age, initial tear size, and fatty degeneration of the supraspinatus as independent risk factors for a rotator cuff retear. Multivariate logistic regression analysis of the single-row group revealed patient age and fatty degeneration of the supraspinatus as independent risk factors for a rotator cuff retear. Multivariate logistic regression analysis of the transosseous-equivalent double-row group revealed a frozen shoulder as an independent risk factor for a rotator cuff retear. Our results suggest that patient age, initial tear size, and fatty degeneration of the supraspinatus are independent risk factors for a rotator cuff retear, whereas the completeness of rotator cuff repair based on the extent of footprint coverage and repair technique are not.

Transtendon, Double-Row, Transosseous-Equivalent Arthroscopic Repair of Partial-Thickness, Articular-Surface Rotator Cuff Tears

PubMed Central

Dilisio, Matthew F.; Miller, Lindsay R.; Higgins, Laurence D.

2014-01-01

Arthroscopic transtendinous techniques for the arthroscopic repair of partial-thickness, articular-surface rotator cuff tears offer the advantage of minimizing the disruption of the patient's remaining rotator cuff tendon fibers. In addition, double-row fixation of full-thickness rotator cuff tears has shown biomechanical advantages. We present a novel method combining these 2 techniques for transtendon, double-row, transosseous-equivalent arthroscopic repair of partial-thickness, articular-surface rotator cuff tears. Direct visualization of the reduction of the retracted articular tendon layer to its insertion on the greater tuberosity is the key to the procedure. Linking the medial-row anchors and using a double-row construct provide a stable repair that allows early shoulder motion to minimize the risk of postoperative stiffness. PMID:25473606

Transtendon, double-row, transosseous-equivalent arthroscopic repair of partial-thickness, articular-surface rotator cuff tears.

PubMed

Dilisio, Matthew F; Miller, Lindsay R; Higgins, Laurence D

2014-10-01

Arthroscopic transtendinous techniques for the arthroscopic repair of partial-thickness, articular-surface rotator cuff tears offer the advantage of minimizing the disruption of the patient's remaining rotator cuff tendon fibers. In addition, double-row fixation of full-thickness rotator cuff tears has shown biomechanical advantages. We present a novel method combining these 2 techniques for transtendon, double-row, transosseous-equivalent arthroscopic repair of partial-thickness, articular-surface rotator cuff tears. Direct visualization of the reduction of the retracted articular tendon layer to its insertion on the greater tuberosity is the key to the procedure. Linking the medial-row anchors and using a double-row construct provide a stable repair that allows early shoulder motion to minimize the risk of postoperative stiffness.

Continuous Symmetry and Chemistry Teachers: Learning Advanced Chemistry Content through Novel Visualization Tools

ERIC Educational Resources Information Center

Tuvi-Arad, Inbal; Blonder, Ron

2010-01-01

In this paper we describe the learning process of a group of experienced chemistry teachers in a specially designed workshop on molecular symmetry and continuous symmetry. The workshop was based on interactive visualization tools that allow molecules and their symmetry elements to be rotated in three dimensions. The topic of continuous symmetry is…

Rotating night shifts too quickly may cause anxiety and decreased attentional performance, and impact prolactin levels during the subsequent day: a case control study.

PubMed

Chang, Yu-San; Chen, Hsiang-Lan; Wu, Yu-Hsuan; Hsu, Chung-Yao; Liu, Ching-Kuan; Hsu, Chin

2014-08-05

We investigated circadian changes and effects on mood, sleep-related hormones and cognitive performance when nurses worked consecutive night shifts in a rapidly rotating shift system. Daytime cognitive function, sleep propensity and sleep-related hormones (growth hormone, cortisol, prolactin, thyrotropin) were compared after participants worked two and four consecutive night shifts. Twenty-three off-duty nurses, 20 nurses working two consecutive night shifts and 16 nurses working four consecutive night shifts were enrolled. All participants completed the Maintenance of Wakefulness Test, State-Trait Anxiety Inventory, Stanford Sleepiness Scale, visual attention tasks (VAT), Wisconsin Card Sorting Test, and modified Multiple Sleep Latency Test. Hormone levels were also measured four times throughout the day, at 2-h intervals. During the day, the participants in the night shift groups were less able to maintain wakefulness, had poor performance on VAT, and higher thyrotropin levels than did those in the off-duty group. Participants who worked two night shifts were better able to maintain wakefulness, had higher anxiety scale scores, poorer initial performance and lack of learning effect on VAT, and higher prolactin levels compared with those who worked four night shifts. There were no differences in cortisol levels between the two- and four- shift groups. Rotating night shifts too quickly may cause anxiety and decreased attentional performance, and may impact daytime prolactin levels after night shifts. It is possible that the two-shift group had a higher cortisol level than did the four-shift group, which would be consistent with the group's higher state anxiety scores. The negative findings may be due to the small sample size. Further studies on the effects of consecutive night shifts on mood and cortisol levels during the daytime after sleep restriction would be valuable.

Influence of Visual Prism Adaptation on Auditory Space Representation.

PubMed

Pochopien, Klaudia; Fahle, Manfred

2017-01-01

Prisms shifting the visual input sideways produce a mismatch between the visual versus felt position of one's hand. Prism adaptation eliminates this mismatch, realigning hand proprioception with visual input. Whether this realignment concerns exclusively the visuo-(hand)motor system or it generalizes to acoustic inputs is controversial. We here show that there is indeed a slight influence of visual adaptation on the perceived direction of acoustic sources. However, this shift in perceived auditory direction can be fully explained by a subconscious head rotation during prism exposure and by changes in arm proprioception. Hence, prism adaptation does only indirectly generalize to auditory space perception.

Impaired visuomotor adaptation in adults with ADHD.

PubMed

Kurdziel, Laura B F; Dempsey, Katherine; Zahara, Mackenzie; Valera, Eve; Spencer, Rebecca M C

2015-04-01

Attention-deficit hyperactivity disorder (ADHD) is a prevalent psychiatric disorder in children that often continues into adulthood. It has been suggested that motor impairments in ADHD are associated with underlying cerebellar pathology. If such is the case, individuals with ADHD should be impaired on motor tasks requiring healthy cerebellar function. To test this, we compared performance of individuals with ADHD and ADHD-like symptoms with non-ADHD controls on a visuomotor adaptation task known to be impaired following cerebellar lesions. Participants adapted reaching movements to a visual representation that was rotated by 30°. Individuals with ADHD and those with ADHD-like symptoms took longer to correct the angle of movement once the rotation was applied relative to controls. However, post-adaptation residual effect did not differ for individuals with ADHD and ADHD-like symptoms compared to the control group. These results are consistent with the hypothesis that mild cerebellar deficits are evident in the motor performance of adults with ADHD.

Visual field information in Nap-of-the-Earth flight by teleoperated Helmet-Mounted displays

NASA Technical Reports Server (NTRS)

Grunwald, Arthur J.; Kohn, S.; Merhav, S. J.

1991-01-01

The human ability to derive Control-Oriented Visual Field Information from teleoperated Helmet-Mounted displays in Nap-of-the-Earth flight, is investigated. The visual field with these types of displays originates from a Forward Looking Infrared Radiation Camera, gimbal-mounted at the front of the aircraft and slaved to the pilot's line-of-sight, to obtain wide-angle visual coverage. Although these displays are proved to be effective in Apache and Cobra helicopter night operations, they demand very high pilot proficiency and work load. Experimental work presented in the paper has shown that part of the difficulties encountered in vehicular control by means of these displays can be attributed to the narrow viewing aperture and head/camera slaving system phase lags. Both these shortcomings will impair visuo-vestibular coordination, when voluntary head rotation is present. This might result in errors in estimating the Control-Oriented Visual Field Information vital in vehicular control, such as the vehicle yaw rate or the anticipated flight path, or might even lead to visuo-vestibular conflicts (motion sickness). Since, under these conditions, the pilot will tend to minimize head rotation, the full wide-angle coverage of the Helmet-Mounted Display, provided by the line-of-sight slaving system, is not always fully utilized.

Implicit and Explicit Representations of Hand Position in Tool Use

PubMed Central

Rand, Miya K.; Heuer, Herbert

2013-01-01

Understanding the interactions of visual and proprioceptive information in tool use is important as it is the basis for learning of the tool's kinematic transformation and thus skilled performance. This study investigated how the CNS combines seen cursor positions and felt hand positions under a visuo-motor rotation paradigm. Young and older adult participants performed aiming movements on a digitizer while looking at rotated visual feedback on a monitor. After each movement, they judged either the proprioceptively sensed hand direction or the visually sensed cursor direction. We identified asymmetric mutual biases with a strong visual dominance. Furthermore, we found a number of differences between explicit and implicit judgments of hand directions. The explicit judgments had considerably larger variability than the implicit judgments. The bias toward the cursor direction for the explicit judgments was about twice as strong as for the implicit judgments. The individual biases of explicit and implicit judgments were uncorrelated. Biases of these judgments exhibited opposite sequential effects. Moreover, age-related changes were also different between these judgments. The judgment variability was decreased and the bias toward the cursor direction was increased with increasing age only for the explicit judgments. These results indicate distinct explicit and implicit neural representations of hand direction, similar to the notion of distinct visual systems. PMID:23894307

The impact of ageing and gender on visual mental imagery processes: A study of performance on tasks from the Complete Visual Mental Imagery Battery (CVMIB).

PubMed

Palermo, Liana; Piccardi, Laura; Nori, Raffaella; Giusberti, Fiorella; Guariglia, Cecilia

2016-09-01

In this study we aim to evaluate the impact of ageing and gender on different visual mental imagery processes. Two hundred and fifty-one participants (130 women and 121 men; age range = 18-77 years) were given an extensive neuropsychological battery including tasks probing the generation, maintenance, inspection, and transformation of visual mental images (Complete Visual Mental Imagery Battery, CVMIB). Our results show that all mental imagery processes with the exception of the maintenance are affected by ageing, suggesting that other deficits, such as working memory deficits, could account for this effect. However, the analysis of the transformation process, investigated in terms of mental rotation and mental folding skills, shows a steeper decline in mental rotation, suggesting that age could affect rigid transformations of objects and spare non-rigid transformations. Our study also adds to previous ones in showing gender differences favoring men across the lifespan in the transformation process, and, interestingly, it shows a steeper decline in men than in women in inspecting mental images, which could partially account for the mixed results about the effect of ageing on this specific process. We also discuss the possibility to introduce the CVMIB in clinical assessment in the context of theoretical models of mental imagery.

Jet Engine Bird Ingestion Simulations: Comparison of Rotating to Non-Rotating Fan Blades

NASA Technical Reports Server (NTRS)

Howard, Samuel A.; Hammer, Jeremiah; Carney, Kelly S.; Pereira, J. Michael

2013-01-01

Bird strike events in commercial airliners are a fairly common occurrence. According to data collected by the US Department of Agriculture, over 80,000 bird strikes were reported in the period 1990-2007 in the US alone [1]. As a result, bird ingestion is an important factor in aero engine design and FAA certification. When it comes to bird impacts on engine fan blades, the FAA requires full-scale bird ingestion tests on an engine running at full speed to pass certification requirements. These rotating tests are complex and very expensive. To reduce development costs associated with new materials for fan blades, it is desirable to develop more cost effective testing procedures than full-scale rotating engine tests for material evaluation. An impact test on a non-rotating single blade that captures most of the salient physics of the rotating test would go a long way towards enabling large numbers of evaluative material screening tests. NASA Glenn Research Center has been working to identify a static blade test procedure that would be effective at reproducing similar results as seen in rotating tests. The current effort compares analytical simulations of a bird strike on various nonrotating blades to a bird strike simulation on a rotating blade as a baseline case. Several different concepts for simulating the rotating loads on a non-rotating blade were analyzed with little success in duplicating the deformation results seen in the rotating case. The rotating blade behaves as if it were stiffer than the non-rotating blade resulting in less plastic deformation from a given bird impact. The key factor limiting the success of the non-rotating blade simulations is thought to be the effect of gyroscopics. Prior to this effort, it was anticipated the difficulty would be in matching the pre-stress in the blade due to centrifugal forces Additional work is needed to verify this assertion, and to determine if a static test procedure can simulate the gyroscopic effects in a suitable manner. This paper describes the various non-rotating concepts analyzed, and demonstrates the effect believed to be gyroscopic in nature on the results.

Jet Engine Bird Ingestion Simulations: Comparison of Rotating to Non-Rotating Fan Blades

NASA Technical Reports Server (NTRS)

Howard, Samuel A.; Hammer, Jeremiah T.; Carney, Kelly S.; Pereira, J. Michael

2013-01-01

Bird strike events in commercial airliners are a fairly common occurrence. According to data collected by the US Department of Agriculture, over 80,000 bird strikes were reported in the period 1990 to 2007 in the US alone (Ref. 1). As a result, bird ingestion is an important factor in aero engine design and FAA certification. When it comes to bird impacts on engine fan blades, the FAA requires full-scale bird ingestion tests on an engine running at full speed to pass certification requirements. These rotating tests are complex and very expensive. To reduce development costs associated with new materials for fan blades, it is desirable to develop more cost effective testing procedures than full-scale rotating engine tests for material evaluation. An impact test on a nonrotating single blade that captures most of the salient physics of the rotating test would go a long way towards enabling large numbers of evaluative material screening tests. NASA Glenn Research Center has been working to identify a static blade test procedure that would be effective at reproducing similar results as seen in rotating tests. The current effort compares analytical simulations of a bird strike on various non-rotating blades to a bird strike simulation on a rotating blade as a baseline case. Several different concepts for simulating the rotating loads on a non-rotating blade were analyzed with little success in duplicating the deformation results seen in the rotating case. The rotating blade behaves as if it were stiffer than the non-rotating blade resulting in less plastic deformation from a given bird impact. The key factor limiting the success of the non-rotating blade simulations is thought to be the effect of gyroscopics. Prior to this effort, it was anticipated the difficulty would be in matching the prestress in the blade due to centrifugal forces Additional work is needed to verify this assertion, and to determine if a static test procedure can simulate the gyroscopic effects in a suitable manner. This paper describes the various non-rotating concepts analyzed, and demonstrates the effect believed to be gyroscopic in nature on the results

Trunk-Rotation Flexibility in Collegiate Softball Players With or Without a History of Shoulder or Elbow Injury

PubMed Central

Aragon, Veronica J.; Oyama, Sakiko; Oliaro, Scott M.; Padua, Darin A.; Myers, Joseph B.

2012-01-01

Context: Throwing is a whole-body motion that requires the transfer of momentum from the lower extremity to the upper extremity via the trunk. No research to date examines the association between a history of shoulder or elbow injury and trunk flexibility in overhead athletes. Objective: To determine if injury history and trunk-rotation flexibility are associated and to compare trunk-rotation flexibility measured using 3 clinical tests: half-kneeling rotation test with the bar in the back, half-kneeling rotation test with the bar in the front, and seated rotation test in softball position players with or without a history of shoulder or elbow injury. Design: Cross-sectional design. Setting: University softball facilities. Patients or Other Participants: Sixty-five female National Collegiate Athletic Association Division I softball position players. Intervention(s): Trunk-rotation flexibility was measured with 3 clinical tests. Recent injury history was obtained using a questionnaire and verified by the certified athletic trainer. Main Outcome Measure(s): Binomial regression models were used to determine if injury history was associated with flexibility categories (high, normal, or limited tertiles) for each of the 6 (3 tests × 2 directions) trunk-rotation flexibility measures. Trunk-rotation flexibility measures from 3 clinical tests were compared between participants with and without a history of shoulder or elbow injury using analysis-of-variance models. Results: When measured using the half-kneeling rotation test with the bar in the back and the seated rotation test, injury history and forward trunk-rotation flexibility were associated. However, no mean group differences were seen in trunk-rotation flexibility between participants with and without a history of shoulder or elbow injury. Conclusions: Limited forward trunk-rotation flexibility may be a risk factor for shoulder or elbow injuries. However, further study is needed to confirm the study finding. PMID:23068587

Acute effects of scapular mobilization in shoulder dysfunction: a double-blind randomized placebo-controlled trial.

PubMed

Surenkok, Ozgur; Aytar, Aydan; Baltaci, Gul

2009-11-01

The aim of this study was to evaluate the initial effects of scapular mobilization (SM) on shoulder range of motion (ROM), scapular upward rotation, pain, and function. Pretest-posttest for 3 groups (SM, sham, and control). A double-blinded, randomized, placebo-controlled trial was conducted to evaluate the initial effect of the SM at a sports physiotherapy clinic. 39 subjects (22 women, 17 men; mean age 54.30 +/- 14.16 y, age range 20-77 y). A visual analog scale, ROM, scapular upward rotation, and function were assessed before and just after SM. SM (n = 13) consisted of the application of superoinferior gliding, rotations, and distraction to the scapula. The sham (n = 13) condition replicated the treatment condition except for the hand positioning. The control group (n = 13) did not undergo any physiotherapy and rehabilitation program. Pain severity was assessed with a visual analog scale. Scapular upward rotation was measured with a baseline digital inclinometer. Constant Shoulder Score (CSS) was used to measure shoulder function. After SM, we found significant improvements for shoulder ROM, scapular upward rotation, and CSS between pretreatment and posttreatment compared with the sham and control groups. In the sham group, shoulder-ROM values increased or decreased for the shoulder and scapular upward rotation was not changed. Pain, ROM, and physical function of the shoulder were not significantly different in the sham group than in controls (P > .05). SM may be a useful manual therapy technique to apply to participants with a painful limitation of the shoulder. SM increases ROM and decreases pain intensity.

Three-dimensional microscopic tomographic imagings of the cataract in a human lens in vivo

NASA Astrophysics Data System (ADS)

Masters, Barry R.

1998-10-01

The problem of three-dimensional visualization of a human lens in vivo has been solved by a technique of volume rendering a transformed series of 60 rotated Scheimpflug (a dual slit reflected light microscope) digital images. The data set was obtained by rotating the Scheimpflug camera about the optic axis of the lens in 3 degree increments. The transformed set of optical sections were first aligned to correct for small eye movements, and then rendered into a volume reconstruction with volume rendering computer graphics techniques. To help visualize the distribution of lens opacities (cataracts) in the living, human lens the intensity of light scattering was pseudocolor coded and the cataract opacities were displayed as a movie.

Demonstrating the Potential for Dynamic Auditory Stimulation to Contribute to Motion Sickness

PubMed Central

Keshavarz, Behrang; Hettinger, Lawrence J.; Kennedy, Robert S.; Campos, Jennifer L.

2014-01-01

Auditory cues can create the illusion of self-motion (vection) in the absence of visual or physical stimulation. The present study aimed to determine whether auditory cues alone can also elicit motion sickness and how auditory cues contribute to motion sickness when added to visual motion stimuli. Twenty participants were seated in front of a curved projection display and were exposed to a virtual scene that constantly rotated around the participant's vertical axis. The virtual scene contained either visual-only, auditory-only, or a combination of corresponding visual and auditory cues. All participants performed all three conditions in a counterbalanced order. Participants tilted their heads alternately towards the right or left shoulder in all conditions during stimulus exposure in order to create pseudo-Coriolis effects and to maximize the likelihood for motion sickness. Measurements of motion sickness (onset, severity), vection (latency, strength, duration), and postural steadiness (center of pressure) were recorded. Results showed that adding auditory cues to the visual stimuli did not, on average, affect motion sickness and postural steadiness, but it did reduce vection onset times and increased vection strength compared to pure visual or pure auditory stimulation. Eighteen of the 20 participants reported at least slight motion sickness in the two conditions including visual stimuli. More interestingly, six participants also reported slight motion sickness during pure auditory stimulation and two of the six participants stopped the pure auditory test session due to motion sickness. The present study is the first to demonstrate that motion sickness may be caused by pure auditory stimulation, which we refer to as “auditorily induced motion sickness”. PMID:24983752

Impairing the useful field of view in natural scenes: Tunnel vision versus general interference.

PubMed

Ringer, Ryan V; Throneburg, Zachary; Johnson, Aaron P; Kramer, Arthur F; Loschky, Lester C

2016-01-01

A fundamental issue in visual attention is the relationship between the useful field of view (UFOV), the region of visual space where information is encoded within a single fixation, and eccentricity. A common assumption is that impairing attentional resources reduces the size of the UFOV (i.e., tunnel vision). However, most research has not accounted for eccentricity-dependent changes in spatial resolution, potentially conflating fixed visual properties with flexible changes in visual attention. Williams (1988, 1989) argued that foveal loads are necessary to reduce the size of the UFOV, producing tunnel vision. Without a foveal load, it is argued that the attentional decrement is constant across the visual field (i.e., general interference). However, other research asserts that auditory working memory (WM) loads produce tunnel vision. To date, foveal versus auditory WM loads have not been compared to determine if they differentially change the size of the UFOV. In two experiments, we tested the effects of a foveal (rotated L vs. T discrimination) task and an auditory WM (N-back) task on an extrafoveal (Gabor) discrimination task. Gabor patches were scaled for size and processing time to produce equal performance across the visual field under single-task conditions, thus removing the confound of eccentricity-dependent differences in visual sensitivity. The results showed that although both foveal and auditory loads reduced Gabor orientation sensitivity, only the foveal load interacted with retinal eccentricity to produce tunnel vision, clearly demonstrating task-specific changes to the form of the UFOV. This has theoretical implications for understanding the UFOV.

Behavioral Assessment of Spaceflight Effects on Neurocognitive Performance: Extent and Longevity

NASA Technical Reports Server (NTRS)

De Dios, Y. E.; Kofman, I. S.; Gadd, N. E.; Kreutzberg, G. A.; Peters, B. T.; Taylor, L. C.; Campbell, D. J.; Wood, S. J.; Bloomberg, J. J.; Seidler, R. D.;

The free-flight response of Drosophila to motion of the visual environment.

PubMed

Mronz, Markus; Lehmann, Fritz-Olaf

2008-07-01

In the present study we investigated the behavioural strategies with which freely flying fruit flies (Drosophila) control their flight trajectories during active optomotor stimulation in a free-flight arena. We measured forward, turning and climbing velocities of single flies using high-speed video analysis and estimated the output of a 'Hassenstein-Reichardt' elementary motion detector (EMD) array and the fly's gaze to evaluate flight behaviour in response to a rotating visual panorama. In a stationary visual environment, flight is characterized by flight saccades during which the animals turn on average 120 degrees within 130 ms. In a rotating environment, the fly's behaviour typically changes towards distinct, concentric circular flight paths where the radius of the paths increases with increasing arena velocity. The EMD simulation suggests that this behaviour is driven by a rotation-sensitive EMD detector system that minimizes retinal slip on each compound eye, whereas an expansion-sensitive EMD system with a laterally centred visual focus potentially helps to achieve centring response on the circular flight path. We developed a numerical model based on force balance between horizontal, vertical and lateral forces that allows predictions of flight path curvature at a given locomotor capacity of the fly. The model suggests that turning flight in Drosophila is constrained by the production of centripetal forces needed to avoid side-slip movements. At maximum horizontal velocity this force may account for up to 70% of the fly's body weight during yaw turning. Altogether, our analyses are widely consistent with previous studies on Drosophila free flight and those on the optomotor response under tethered flight conditions.

Cross-axis adaptation of torsional components in the yaw-axis vestibulo-ocular reflex

NASA Technical Reports Server (NTRS)

Trillenberg, P.; Shelhamer, M.; Roberts, D. C.; Zee, D. S.

2003-01-01

The three pairs of semicircular canals within the labyrinth are not perfectly aligned with the pulling directions of the six extraocular muscles. Therefore, for a given head movement, the vestibulo-ocular reflex (VOR) depends upon central neural mechanisms that couple the canals to the muscles with the appropriate functional gains in order to generate a response that rotates the eye the correct amount and around the correct axis. A consequence of these neural connections is a cross-axis adaptive capability, which can be stimulated experimentally when head rotation is around one axis and visual motion about another. From this visual-vestibular conflict the brain infers that the slow-phase eye movement is rotating around the wrong axis. We explored the capability of human cross-axis adaptation, using a short-term training paradigm, to determine if torsional eye movements could be elicited by yaw (horizontal) head rotation (where torsion is normally inappropriate). We applied yaw sinusoidal head rotation (+/-10 degrees, 0.33 Hz) and measured eye movement responses in the dark, and before and after adaptation. The adaptation paradigm lasted 45-60 min, and consisted of the identical head motion, coupled with a moving visual scene that required one of several types of eye movements: (1) torsion alone (-Roll); (2) horizontal/torsional, head right/CW torsion (Yaw-Roll); (3) horizontal/torsional, head right/CCW torsion (Yaw+Roll); (4) horizontal, vertical, torsional combined (Yaw+Pitch-Roll); and (5) horizontal and vertical together (Yaw+Pitch). The largest and most significant changes in torsional amplitude occurred in the Yaw-Roll and Yaw+Roll conditions. We conclude that short-term, cross-axis adaptation of torsion is possible but constrained by the complexity of the adaptation task: smaller torsional components are produced if more than one cross-coupling component is required. In contrast, vertical cross-axis components can be easily trained to occur with yaw head movements.

Surface ablation with iris recognition and dynamic rotational eye tracking-based tissue saving treatment with the Technolas 217z excimer laser.

PubMed

Prakash, Gaurav; Agarwal, Amar; Kumar, Dhivya Ashok; Jacob, Soosan; Agarwal, Athiya; Maity, Amrita

2011-03-01

To evaluate the visual and refractive outcomes and expected benefits of Tissue Saving Treatment algorithm-guided surface ablation with iris recognition and dynamic rotational eye tracking. This prospective, interventional case series comprised 122 eyes (70 patients). Pre- and postoperative assessment included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction, and higher order aberrations. All patients underwent Tissue Saving Treatment algorithm-guided surface ablation with iris recognition and dynamic rotational eye tracking using the Technolas 217z 100-Hz excimer platform (Technolas Perfect Vision GmbH). Follow-up was performed up to 6 months postoperatively. Theoretical benefit analysis was performed to evaluate the algorithm's outcomes compared to others. Preoperative spherocylindrical power was sphere -3.62 ± 1.60 diopters (D) (range: 0 to -6.75 D), cylinder -1.15 ± 1.00 D (range: 0 to -3.50 D), and spherical equivalent -4.19 ± 1.60 D (range: -7.75 to -2.00 D). At 6 months, 91% (111/122) of eyes were within ± 0.50 D of attempted correction. Postoperative UDVA was comparable to preoperative CDVA at 1 month (P=.47) and progressively improved at 6 months (P=.004). Two eyes lost one line of CDVA at 6 months. Theoretical benefit analysis revealed that of 101 eyes with astigmatism, 29 would have had cyclotorsion-induced astigmatism of ≥ 10% if iris recognition and dynamic rotational eye tracking were not used. Furthermore, the mean percentage decrease in maximum depth of ablation by using the Tissue Saving Treatment was 11.8 ± 2.9% over Aspheric, 17.8 ± 6.2% over Personalized, and 18.2 ± 2.8% over Planoscan algorithms. Tissue saving surface ablation with iris recognition and dynamic rotational eye tracking was safe and effective in this series of eyes. Copyright 2011, SLACK Incorporated.

Effects of bone marrow aspirate concentrate and platelet-rich plasma on patients with partial tear of the rotator cuff tendon.

PubMed

Kim, Sang Jun; Kim, Eun Kyung; Kim, Sun Jeong; Song, Da Hyun

2018-01-03

We compared the clinical course of rotator cuff tears between rotator cuff exercise and bone marrow aspirate concentration (BMAC)-platelet rich plasma (PRP) injection to identify the therapeutic effects of BMAC-PRP on partial tear of the rotator cuff tendon. Twenty-four patients with partial tear of the rotator cuff tendon participated in this study. Twelve patients underwent extraction of BMACs and PRP and received the injection of BMAC-PRP at the tear site under ultrasound guidance. Twelve patients in the control group were asked to perform the rotator cuff exercise for 3 months. Visual analog scale (VAS) and manual muscle test (MMT) scores of the supraspinatus muscle were measured, and the American Shoulder and Elbow Surgeons (ASES) score was recorded before, 3 weeks, and 3 months after injection. Tear size was measured by the greatest longitudinal tear length. The change in the VAS differed between groups at 3 months (P = 0.039) but not at 3 weeks (P = 0.147). The ASES scores in the BMAC-PRP group changed from 39.4 ± 13.0 to 54.5 ± 11.5 at 3 weeks and 74.1 ± 8.5 at 3 months while those in the control group changed from 45.9 ± 12.4 to 56.3 ± 12.3 at 3 weeks (P = 0.712) and 62.2 ± 12.2 at 3 months (P = 0.011). The tear size decreased at 3 weeks or 3 months after the BMAC-PRP injection but was not significantly different from that in the control group. BMAC-PRP improved pain and shoulder function in patients with partial tear of the rotator cuff tendon. The patients were registered in the institutional board registry of Samsung Medical Center (registry number 2014-07-173 ).

Isolated Subscapularis Repair in Irreparable Posterosuperior Massive Rotator Cuff Tears Involving the Subscapularis Tendon.

PubMed

Kim, Sung-Jae; Choi, Yun-Rak; Jung, Min; Lee, Won-Yong; Chun, Yong-Min

2017-05-01

No previous study has examined whether isolated subscapularis tendon repair in irreparable posterosuperior massive rotator tears involving the subscapularis tendon in relatively young patients without arthritis can yield satisfactory outcomes. We hypothesized that this procedure would produce favorable outcomes in patients who might otherwise be candidates for reverse arthroplasty. Case series; Level of evidence, 4. This retrospective study included 24 patients in their 50s and 60s, without shoulder arthritis, who underwent arthroscopic isolated subscapularis repair for an irreparable massive rotator cuff tear involving the subscapularis tendon. Preoperative and postoperative visual analog scale (VAS) pain scores, subjective shoulder values (SSVs), University of California at Los Angeles (UCLA) shoulder scores, American Shoulder and Elbow Surgeons (ASES) scores, subscapularis strength (modified bell-press test; maximum of 5), and shoulder active range of motion (ROM) were assessed. Postoperative magnetic resonance arthrography (MRA) was performed 6 months postoperatively to assess structural integrity of the repaired subscapularis. At a mean 34.8 months (range, 24-49 months) of follow-up, VAS pain scores (improved from 7.1 to 2.5), SSVs (33.3 to 75.2), ASES scores (35.9 to 76.0), UCLA shoulder scores (11.6 to 24.8), subscapularis strength, and ROM were significantly improved compared with preoperative measurements ( P < .001). Subscapularis muscle strength improved from 3.7 to 4.2 ( P < .001). For active ROM, forward flexion and internal rotation improved significantly ( P < .001); however, external rotation exhibited no significant improvement. Follow-up MRA was performed in 22 patients (92%) and showed retear of the repaired subscapularis in 6 (27% of the 22). Isolated repair of the subscapularis tendon in irreparable massive rotator cuff tears involving the subscapularis tendon yielded satisfactory short-term outcomes and structural integrity in patients in their 50s and 60s without arthritis. If patients with irreparable massive rotator cuff tears involving the subscapularis tendon are relatively young or have minimal concomitant arthritis, this repair can be worthwhile.

Laboratory and field testing of commercial rotational seismometers

USGS Publications Warehouse

Nigbor, R.L.; Evans, J.R.; Hutt, C.R.

2009-01-01

There are a small number of commercially available sensors to measure rotational motion in the frequency and amplitude ranges appropriate for earthquake motions on the ground and in structures. However, the performance of these rotational seismometers has not been rigorously and independently tested and characterized for earthquake monitoring purposes as is done for translational strong- and weak-motion seismometers. Quantities such as sensitivity, frequency response, resolution, and linearity are needed for the understanding of recorded rotational data. To address this need, we, with assistance from colleagues in the United States and Taiwan, have been developing performance test methodologies and equipment for rotational seismometers. In this article the performance testing methodologies are applied to samples of a commonly used commercial rotational seismometer, the eentec model R-1. Several examples were obtained for various test sequences in 2006, 2007, and 2008. Performance testing of these sensors consisted of measuring: (1) sensitivity and frequency response; (2) clip level; (3) self noise and resolution; and (4) cross-axis sensitivity, both rotational and translational. These sensor-specific results will assist in understanding the performance envelope of the R-1 rotational seismometer, and the test methodologies can be applied to other rotational seismometers.

Impact of rotation angle on crawling and non-crawling 9-month-old infants' mental rotation ability.

PubMed

Gerhard, Theresa M; Schwarzer, Gudrun

2018-06-01

The current study investigated whether 9-month-old infants' mental rotation performance was influenced by the magnitude of the angle of object rotation and their crawling ability. A total of 76 infants were tested; of these infants, 39 had been crawling for an average of 9.0 weeks. Infants were habituated to a video of a simplified Shepard-Metzler object (Shepard & Metzler, 1971), always rotating forward through a 180° angle around the horizontal axis of the object. After habituation, in two different test conditions, infants were presented with test videos of the same object rotating farther forward through a previously unseen 90° angle and with a test video of its mirror image. The two test conditions differed in the magnitude of the gap between the end of the habituation rotations and the beginning of the test rotations. The gaps were 0° and 54°. The results revealed that the mental rotation performance was influenced by the magnitude of the gaps only for the crawling infants. Their response showed significant transition from a preference for the mirror object rotations toward a preference for the familiar habituation object rotations. Thus, the results provide first evidence that it is easier for 9-month-old crawling infants to mentally rotate an object along a small angle compared with a large one. Copyright © 2018 Elsevier Inc. All rights reserved.

Functional Mobility Performance and Balance Confidence in Older Adults after Sensorimotor Adaptation Training

NASA Technical Reports Server (NTRS)

Buccello-Stout, Regina R.; Cromwell, Ronita L.; Bloomberg, Jacob J.; Weaver, G. D.

2010-01-01

Research indicates a main contributor of injury in older adults is from falling. The decline in sensory systems limits information needed to successfully maneuver through the environment. The objective of this study was to determine if prolonged exposure to the realignment of perceptual-motor systems increases adaptability of balance, and if balance confidence improves after training. A total of 16 older adults between ages 65-85 were randomized to a control group (walking on a treadmill while viewing a static visual scene) and an experimental group (walking on a treadmill while viewing a rotating visual scene). Prior to visual exposure, participants completed six trials of walking through a soft foamed obstacle course. Participants came in twice a week for 4 weeks to complete training of walking on a treadmill and viewing the visual scene for 20 minutes each session. Participants completed the obstacle course after training and four weeks later. Average time, penalty, and Activity Balance Confidence Scale scores were computed for both groups across testing times. The older adults who trained, significantly improved their time through the obstacle course F (2, 28) = 9.41, p < 0.05, as well as reduced their penalty scores F (2, 28) = 21.03, p < 0.05, compared to those who did not train. There was no difference in balance confidence scores between groups across testing times F (2, 28) = 0.503, p > 0.05. Although the training group improved mobility through the obstacle course, there were no differences between the groups in balance confidence.

Searching for bumps and ellipses on the ground and in the sky: no advantage for the ground plane.

PubMed

Jóhannesson, Omar I; Sigurdardottir, Kristín Ósk; Kristjánsson, Arni

2013-11-01

A staple of modern theories of vision is that the visual system has evolved to perceive cues containing the most predictive information about the layout of the environment. This entails the prediction that - other things being equal - visual performance in a familiar setting should be superior to performance in an unfamiliar one. Visual performance should therefore be better on the familiar ground plane compared to an implied sky or wall plane. We tested this comparing visual search for stimuli presented in an implied ground plane with search on a 180° rotated search display so that the stimuli appeared in an implied "sky" plane, and with search in a random layout implying no depth. This was tested for stimuli with, or without, curvature discontinuities, that have previously been shown to be strong cues for shape analysis. Surprisingly, no advantage of the ground plane over the sky plane was observed, while a strong effect of layout regularity was seen. Similarly, in experiment 2 there was little effect of placing the stimuli on an implied wall plane compared to the ground or the sky. The results are not explained by assuming that curvature discontinuities are such strong cues that they overshadow any effect of depth-plane, since there was a strong effect of regular versus random layout, which should also have disappeared under this account. The results argue instead for a very strong effect of layout regularity, unrelated to environmental regularities in evolutionary history, since there was no ground-plane benefit. Copyright © 2013 Elsevier B.V. All rights reserved.

Virtual-reality-Based 3D navigation training for emergency egress from spacecraft.

PubMed

Aoki, Hirofumi; Oman, Charles M; Natapoff, Alan

2007-08-01

Astronauts have reported spatial disorientation and navigation problems inside spacecraft whose interior visual vertical direction varies from module to module. If they had relevant preflight practice they might orient better. This experiment examined the influence of relative body orientation and individual spatial skills during VR training on a simulated emergency egress task. During training, 36 subjects were each led on 12 tours through a space station by a virtual tour guide. Subjects wore a head-mounted display and controlled their motion with a game-pad. Each tour traversed multiple modules and involved up to three changes in visual vertical direction. Each subject was assigned to one of three groups that maintained different postures: visually upright relative to the "local" module; constant orientation relative to the "station" irrespective of local visual vertical; and "mixed" (local, followed by station orientation). Groups were balanced on the basis of mental rotation and perspective-taking test scores. Subjects then performed 24 emergency egress testing trials without the tour guide. Smoke reduced visibility during the last 12 trials. Egress time, sense of direction (by pointing to origin and destination) and configuration knowledge were measured. Both individual 3D spatial abilities and orientation during training influence emergency egress performance, pointing, and configuration knowledge. Local training facilitates landmark and route learning, but station training enhances sense of direction relative to station, and, therefore, performance in low visibility. We recommend a sequence of local, followed by station, and then randomized orientation training, preferably customized to a trainee's 3D spatial ability.

360-degree 3D transvaginal ultrasound system for high-dose-rate interstitial gynaecological brachytherapy needle guidance

NASA Astrophysics Data System (ADS)

Rodgers, Jessica R.; Surry, Kathleen; D'Souza, David; Leung, Eric; Fenster, Aaron

2017-03-01

Treatment for gynaecological cancers often includes brachytherapy; in particular, in high-dose-rate (HDR) interstitial brachytherapy, hollow needles are inserted into the tumour and surrounding area through a template in order to deliver the radiation dose. Currently, there is no standard modality for visualizing needles intra-operatively, despite the need for precise needle placement in order to deliver the optimal dose and avoid nearby organs, including the bladder and rectum. While three-dimensional (3D) transrectal ultrasound (TRUS) imaging has been proposed for 3D intra-operative needle guidance, anterior needles tend to be obscured by shadowing created by the template's vaginal cylinder. We have developed a 360-degree 3D transvaginal ultrasound (TVUS) system that uses a conventional two-dimensional side-fire TRUS probe rotated inside a hollow vaginal cylinder made from a sonolucent plastic (TPX). The system was validated using grid and sphere phantoms in order to test the geometric accuracy of the distance and volumetric measurements in the reconstructed image. To test the potential for visualizing needles, an agar phantom mimicking the geometry of the female pelvis was used. Needles were inserted into the phantom and then imaged using the 3D TVUS system. The needle trajectories and tip positions in the 3D TVUS scan were compared to their expected values and the needle tracks visualized in magnetic resonance images. Based on this initial study, 360-degree 3D TVUS imaging through a sonolucent vaginal cylinder is a feasible technique for intra-operatively visualizing needles during HDR interstitial gynaecological brachytherapy.

Mental Rotation Performance in Male Soccer Players

PubMed Central

Jansen, Petra; Lehmann, Jennifer; Van Doren, Jessica

2012-01-01

It is the main goal of this study to investigate the visual-spatial cognition in male soccer players. Forty males (20 soccer players and 20 non-athletes) solved a chronometric mental rotation task with both cubed and embodied figures (human figures, body postures). The results confirm previous results that all participants had a lower mental rotation speed for cube figures compared to embodied figures and a higher error rate for cube figures, but only at angular disparities greater than 90°. It is a new finding that soccer–players showed a faster reaction time for embodied stimuli. Because rotation speed did not differ between soccer-players and non-athletes this finding cannot be attributed to the mental rotation process itself but instead to differences in one of the following processes which are involved in a mental rotation task: the encoding process, the maintanence of readiness, or the motor process. The results are discussed against the background of the influence on longterm physical activity on mental rotation and the context of embodied cognition. PMID:23119073

Multiple-object permanence tracking: limitation in maintenance and transformation of perceptual objects.

PubMed

Saiki, Jun

2002-01-01

Research on change blindness and transsaccadic memory revealed that a limited amount of information is retained across visual disruptions in visual working memory. It has been proposed that visual working memory can hold four to five coherent object representations. To investigate their maintenance and transformation in dynamic situations, I devised an experimental paradigm called multiple-object permanence tracking (MOPT) that measures memory for multiple feature-location bindings in dynamic situations. Observers were asked to detect any color switch in the middle of a regular rotation of a pattern with multiple colored disks behind an occluder. The color-switch detection performance dramatically declined as the pattern rotation velocity increased, and this effect of object motion was independent of the number of targets. The MOPT task with various shapes and colors showed that color-shape conjunctions are not available in the MOPT task. These results suggest that even completely predictable motion severely reduces our capacity of object representations, from four to only one or two.

Fundamental Study of Material Flow in Friction Stir Welds

NASA Technical Reports Server (NTRS)

Reynolds, Anthony P.

1999-01-01

The presented research project consists of two major parts. First, the material flow in solid-state, friction stir, butt-welds as been investigated using a marker insert technique. Changes in material flow due to welding parameter as well as tool geometry variations have been examined for different materials. The method provides a semi-quantitative, three-dimensional view of the material transport in the welded zone. Second, a FSW process model has been developed. The fully coupled model is based on fluid mechanics; the solid-state material transport during welding is treated as a laminar, viscous flow of a non-Newtonian fluid past a rotating circular cylinder. The heat necessary for the material softening is generated by deformation of the material. As a first step, a two-dimensional model, which contains only the pin of the FSW tool, has been created to test the suitability of the modeling approach and to perform parametric studies of the boundary conditions. The material flow visualization experiments agree very well with the predicted flow field. Accordingly, material within the pin diameter is transported only in the rotation direction around the pin. Due to the simplifying assumptions inherent in the 2-D model, other experimental data such as forces on the pin, torque, and weld energy cannot be directly used for validation. However, the 2-D model predicts the same trends as shown in the experiments. The model also predicts a deviation from the "normal" material flow at certain combinations of welding parameters, suggesting a possible mechanism for the occurrence of some typical FSW defects. The next step has been the development of a three-dimensional process model. The simplified FSW tool has been designed as a flat shoulder rotating on the top of the workpiece and a rotating, cylindrical pin, which extends throughout the total height of the flow domain. The thermal boundary conditions at the tool and at the contact area to the backing plate have been varied to fit experimental data such as temperature profiles, torque and tool forces. General aspects of the experimentally visualized material flow pattern are confirmed by the 3-D model.

Choice-reaction time to visual motion with varied levels of simultaneous rotary motion

NASA Technical Reports Server (NTRS)

Clark, B.; Stewart, J. D.

1974-01-01

Twelve airline pilots were studied to determine the effects of whole-body rotation on choice-reaction time to the horizontal motion of a line on a cathode-ray tube. On each trial, one of five levels of visual acceleration and five corresponding proportions of rotary acceleration were presented simultaneously. Reaction time to the visual motion decreased with increasing levels of visual motion and increased with increasing proportions of rotary acceleration. The results conflict with general theories of facilitation during double stimulation but are consistent with neural-clock model of sensory interaction in choice-reaction time.

Development of a multicomponent force and moment balance for water tunnel applications, volume 2

NASA Technical Reports Server (NTRS)

Suarez, Carlos J.; Malcolm, Gerald N.; Kramer, Brian R.; Smith, Brooke C.; Ayers, Bert F.

1994-01-01

The principal objective of this research effort was to develop a multicomponent strain gauge balance to measure forces and moments on models tested in flow visualization water tunnels. Static experiments (which are discussed in Volume 1 of this report) were conducted, and the results showed good agreement with wind tunnel data on similar configurations. Dynamic experiments, which are the main topic of this Volume, were also performed using the balance. Delta wing models and two F/A-18 models were utilized in a variety of dynamic tests. This investigation showed that, as expected, the values of the inertial tares are very small due to the low rotating rates required in a low-speed water tunnel and can, therefore, be ignored. Oscillations in pitch, yaw and roll showed hysteresis loops that compared favorably to data from dynamic wind tunnel experiments. Pitch-up and hold maneuvers revealed the long persistence, or time-lags, of some of the force components in response to the motion. Rotary-balance experiments were also successfully performed. The good results obtained in these dynamic experiments bring a whole new dimension to water tunnel testing and emphasize the importance of having the capability to perform simultaneous flow visualization and force/moment measurements during dynamic situations.

Auralization of CFD Vorticity Using an Auditory Illusion

NASA Astrophysics Data System (ADS)

Volpe, C. R.

2005-12-01

One way in which scientists and engineers interpret large quantities of data is through a process called visualization, i.e. generating graphical images that capture essential characteristics and highlight interesting relationships. Another approach, which has received far less attention, is to present complex information with sound. This approach, called ``auralization" or ``sonification", is the auditory analog of visualization. Early work in data auralization frequently involved directly mapping some variable in the data to a sound parameter, such as pitch or volume. Multi-variate data could be auralized by mapping several variables to several sound parameters simultaneously. A clear drawback of this approach is the limited practical range of sound parameters that can be presented to human listeners without exceeding their range of perception or comfort. A software auralization system built upon an existing visualization system is briefly described. This system incorporates an aural presentation synchronously and interactively with an animated scientific visualization, so that alternate auralization techniques can be investigated. One such alternate technique involves auditory illusions: sounds which trick the listener into perceiving something other than what is actually being presented. This software system will be used to present an auditory illusion, known for decades among cognitive psychologists, which produces a sound that seems to ascend or descend endlessly in pitch. The applicability of this illusion for presenting Computational Fluid Dynamics data will be demonstrated. CFD data is frequently visualized with thin stream-lines, but thicker stream-ribbons and stream-tubes can also be used, which rotate to convey fluid vorticity. But a purely graphical presentation can yield drawbacks of its own. Thicker stream-tubes can be self-obscuring, and can obscure other scene elements as well, thus motivating a different approach, such as using sound. Naturally, the simple approach of mapping clockwise and counterclockwise rotations to actual pitch increases and decreases, eventually results in sounds that the listener cannot hear. In this alternate presentation using an auditory illusion, repeated rotations of a stream-tube are replaced with continual increases or decreases in apparent pitch. These apparent pitch changes can continue without bound, yet never exceed the range of frequencies that the listener can hear. The effectiveness of this presentation technique has been studied, and empirical results, obtained through formal user testing and statistical analysis, are presented. These results demonstrate that an aural data presentation using an auditory illusion can improve performance in locating key data characteristics, a task that demonstrates a certain level of understanding of the data. The experiments show that this holds true even when the user expresses a subjective preference and greater confidence in a visual presentation. The CFD data used in the research comes from a number of different industrial domains, but the advantages of this technique could be equally applicable to the study of earth sciences involving fluid mechanics, such as atmospheric or ocean sciences. Furthermore, the approach is applicable not only to CFD data, but to any type of data in which a quantity that is cyclic in nature, such as orientation, needs to be presented. Although the techniques and tools were originally developed with scientists and engineers in mind, they can also be used to aid students, particularly those who are visually impaired or who have difficulty interpreting certain spatial relationships visually.

Red to Green or Fast to Slow? Infants' Visual Working Memory for "Just Salient Differences"

ERIC Educational Resources Information Center

Kaldy, Zsuzsa; Blaser, Erik

2013-01-01

In this study, 6-month-old infants' visual working memory for a static feature (color) and a dynamic feature (rotational motion) was compared. Comparing infants' use of different features can only be done properly if experimental manipulations to those features are equally salient (Kaldy & Blaser, 2009; Kaldy, Blaser, & Leslie,…

The Effects of Various Fidelity Factors on Simulated Helicopter Hover

DTIC Science & Technology

1981-01-01

18 VISUAL DISPLAY ....... ....................... ... 20 §. AUDITORY CUES ........... ........................ 23 • SHIP MOTION MODEL...and DiCarlo, 1974), the evaluation of visual, auditory , and motion cues for helicopter simulation (Parrish, Houck, and Martin, 1977), and the...supply the cue. As the tilt should be supplied subliminally , a forward/aft translation must be used to cue the acceleration’s onset. If only rotation

Exploring Verbal, Visual and Schematic Learners' Static and Dynamic Mental Images of Scientific Species and Processes in Relation to Their Spatial Ability

ERIC Educational Resources Information Center

Al-Balushi, Sulaiman M.; Coll, Richard Kevin

2013-01-01

The current study compared different learners' static and dynamic mental images of unseen scientific species and processes in relation to their spatial ability. Learners were classified into verbal, visual and schematic. Dynamic images were classified into: appearing/disappearing, linear-movement, and rotation. Two types of scientific entities and…

Nonlinearity in the rotational dynamics of Haidinger's brushes

NASA Astrophysics Data System (ADS)

Rothmayer, Mark; Dultz, Wolfgang; Frins, Erna; Zhan, Qiwen; Tierney, Dennis; Schmitzer, Heidrun

2007-10-01

Haidinger's brushes are an entoptic effect of the human visual system that enables us to detect polarized light. However, individual perceptions of Haidinger's brushes can vary significantly. We find that the birefringence of the cornea influences the rotational motion and the contrast of Haidinger's brushes and may offer an explanation for individual differences. We have devised an experimental setup to simulate various phase shifts of the cornea and found a switching effect in the rotational dynamics of Haidinger's brushes. In addition, age related macular degeneration reduces the polarization effect of the macula and thus also leads to changes in the brush pattern.

Spinal cord injury affects the interplay between visual and sensorimotor representations of the body

PubMed Central

Ionta, Silvio; Villiger, Michael; Jutzeler, Catherine R; Freund, Patrick; Curt, Armin; Gassert, Roger

2016-01-01

The brain integrates multiple sensory inputs, including somatosensory and visual inputs, to produce a representation of the body. Spinal cord injury (SCI) interrupts the communication between brain and body and the effects of this deafferentation on body representation are poorly understood. We investigated whether the relative weight of somatosensory and visual frames of reference for body representation is altered in individuals with incomplete or complete SCI (affecting lower limbs’ somatosensation), with respect to controls. To study the influence of afferent somatosensory information on body representation, participants verbally judged the laterality of rotated images of feet, hands, and whole-bodies (mental rotation task) in two different postures (participants’ body parts were hidden from view). We found that (i) complete SCI disrupts the influence of postural changes on the representation of the deafferented body parts (feet, but not hands) and (ii) regardless of posture, whole-body representation progressively deteriorates proportionally to SCI completeness. These results demonstrate that the cortical representation of the body is dynamic, responsive, and adaptable to contingent conditions, in that the role of somatosensation is altered and partially compensated with a change in the relative weight of somatosensory versus visual bodily representations. PMID:26842303

Visual cueing considerations in Nap-of-the-Earth helicopter flight head-slaved helmet-mounted displays

NASA Technical Reports Server (NTRS)

Grunwald, Arthur J.; Kohn, Silvia

1993-01-01

The pilot's ability to derive Control-Oriented Visual Field Information from teleoperated Helmet-Mounted displays in Nap-of-the-Earth flight, is investigated. The visual field with these types of displays, commonly used in Apache and Cobra helicopter night operations, originates from a relatively narrow field-of-view Forward Looking Infrared Radiation Camera, gimbal-mounted at the nose of the aircraft and slaved to the pilot's line-of-sight, in order to obtain a wide-angle field-of-regard. Pilots have encountered considerable difficulties in controlling the aircraft by these devices. Experimental simulator results presented here indicate that part of these difficulties can be attributed to head/camera slaving system phase lags and errors. In the presence of voluntary head rotation, these slaving system imperfections are shown to impair the Control-Oriented Visual Field Information vital in vehicular control, such as the perception of the anticipated flight path or the vehicle yaw rate. Since, in the presence of slaving system imperfections, the pilot will tend to minimize head rotation, the full wide-angle field-of-regard of the line-of-sight slaved Helmet-Mounted Display, is not always fully utilized.

Self-sustained flow oscillations and heat transfer in radial flow through co-rotating parallel disks

NASA Astrophysics Data System (ADS)

Mochizuki, S.; Inoue, T.

1990-03-01

An experimental study was conducted to determine the fluid flow and heat transfer characteristics in a passage formed by two parallel rotating disks. The local heat transfer coefficients along the disk radius were measured in detail and the flow patterns between the two rotating disks were visualized by using paraffin mist and a laser-light sheet. It was disclosed that: (1) the self-sustained laminar flow separation which is characteristic of the stationary disks still exists even when the disks are set in motion, giving significant influence to the heat transfer; (2) for small source flow Reynolds number, Re, and large rotational Reynolds number, Re(omega), rotating stall dominates the heat transfer; and (3) heat transfer for steady laminar flow occurs only when Re is less than 1200 and Re(omega) is less than 20.

Compensatory increase of the cervico-ocular reflex with age in healthy humans

PubMed Central

Kelders, W P A; Kleinrensink, G J; van der Geest, J N; Feenstra, L; de Zeeuw, C I; Frens, M A

2003-01-01

The cervico-ocular reflex (COR) is an ocular stabilization reflex that is elicited by rotation of the neck. It works in conjunction with the vestibulo-ocular reflex (VOR) and the optokinetic reflex (OKR) in order to prevent visual slip over the retina due to self-motion. The gains of the VOR and OKR are known to decrease with age. We have investigated whether the COR, a reflexive eye movement elicited by rotation of the neck, shows a compensatory increase and whether a synergy exists between the COR and the other ocular stabilization reflexes. In the present study 35 healthy subjects of varying age (20–86 years) were rotated in the dark in a trunk-to-head manner (the head fixed in spaced with the body passively rotated under it) at peak velocities between 2.1 and 12.6 deg s−1 as a COR stimulus. Another 15 were subjected to COR, VOR and OKR stimuli at frequencies between 0.04 and 0.1 Hz. Three subjects participated in both tests. The position of the eyes was recorded with an infrared recording technique. We found that the COR-gain increases with increasing age and that there is a significant covariation between the gains of the VOR and COR, meaning that when VOR increases, COR decreases and vice versa. A nearly constant phase lag between the COR and the VOR of about 25 deg existed at all stimulus frequencies. PMID:12949226

Misalignment Effect Function Measurement for Oblique Rotation Axes: Counterintuitive Predictions and Theoretical Extensions

NASA Technical Reports Server (NTRS)

Ellis, Stephen R.; Adelstein, Bernard D.; Yeom, Kiwon

2013-01-01

The Misalignment Effect Function (MEF) describes the decrement in manual performance associated with a rotation between operators' visual display frame of reference and that of their manual control. It now has been empirically determined for rotation axes oblique to canonical body axes and is compared with the MEF previously measured for rotations about canonical axes. A targeting rule, called the Secant Rule, based on these earlier measurements is derived from a hypothetical process and shown to describe some of the data from three previous experiments. It explains the motion trajectories determined for rotations less than 65deg in purely kinematic terms without the need to appeal to a mental rotation process. Further analysis of this rule in three dimensions applied to oblique rotation axes leads to a somewhat surprising expectation that the difficulty posed by rotational misalignment should get harder as the required movement is shorter. This prediction is confirmed. Geometry underlying this rule also suggests analytic extensions for predicting more generally the difficulty of making movements in arbitrary directions subject to arbitrary misalignments.

Keeping It in Three Dimensions: Measuring the Development of Mental Rotation in Children with the Rotated Colour Cube Test (RCCT)

ERIC Educational Resources Information Center

Lutke, Nikolay; Lange-Kuttner, Christiane

2015-01-01

This study introduces the new Rotated Colour Cube Test (RCCT) as a measure of object identification and mental rotation using single 3D colour cube images in a matching-to-sample procedure. One hundred 7- to 11-year-old children were tested with aligned or rotated cube models, distracters and targets. While different orientations of distracters…

The Vestibular System and Human Dynamic Space Orientation

NASA Technical Reports Server (NTRS)

Meiry, J. L.

1966-01-01

The motion sensors of the vestibular system are studied to determine their role in human dynamic space orientation and manual vehicle control. The investigation yielded control models for the sensors, descriptions of the subsystems for eye stabilization, and demonstrations of the effects of motion cues on closed loop manual control. Experiments on the abilities of subjects to perceive a variety of linear motions provided data on the dynamic characteristics of the otoliths, the linear motion sensors. Angular acceleration threshold measurements supplemented knowledge of the semicircular canals, the angular motion sensors. Mathematical models are presented to describe the known control characteristics of the vestibular sensors, relating subjective perception of motion to objective motion of a vehicle. The vestibular system, the neck rotation proprioceptors and the visual system form part of the control system which maintains the eye stationary relative to a target or a reference. The contribution of each of these systems was identified through experiments involving head and body rotations about a vertical axis. Compensatory eye movements in response to neck rotation were demonstrated and their dynamic characteristics described by a lag-lead model. The eye motions attributable to neck rotations and vestibular stimulation obey superposition when both systems are active. Human operator compensatory tracking is investigated in simple vehicle orientation control system with stable and unstable controlled elements. Control of vehicle orientation to a reference is simulated in three modes: visual, motion and combined. Motion cues sensed by the vestibular system through tactile sensation enable the operator to generate more lead compensation than in fixed base simulation with only visual input. The tracking performance of the human in an unstable control system near the limits of controllability is shown to depend heavily upon the rate information provided by the vestibular sensors.

Effect of low level laser (LLL) on cochlear and vestibular inner ear including tinnitus

NASA Astrophysics Data System (ADS)

Rhee, Chung-Ku; Lim, Eun-Seok; Kim, Young-Saeng; Chung, Yong-Won; Jung, Jae-Yun; Chung, Phil-Sang

2006-02-01

Objectives: 1. To investigate preventive effect of LLL on gentamicin-induced vestibular ototoxicity. 2. To evaluate the effectiveness of lower level laser (LLL) in the treatment of tinnitus. Methods: 1. Twenty guinea pigs were divided into control and laser groups. Vestibular ototoxicity was induced by intratympanic injection of gentamicin into left ear. LLL was irradiated into left ear canal of animals in laser group. Vestibular function of the animals was evaluated with vertical and off-vertical axis rotation testing. 2. Forty patients with tinnitus were treated with ginkgo biloba orally and randomly divided into control and laser groups. The 20 patients of laser group received 80.4 J/cm2 of 830 nm laser, 3 times per week for 4 weeks, via transmeatal irradiation. Tinnitus was evaluated by visual analogue scale (VAS) and tinnitus handicap inventory (THI). Results: 1. Preventive effect of LLL to gentamicin induced vestibular ototoxicity was demonstrated by preventing reduction of gain in slow harmonic acceleration test and modulation in the off-vertical axis rotation test. 2. Eleven of 20 laser group patients have shown significant improvement in VAS and THI compared to those of the control group. Conclusions: 1. LLL therapy may have preventive effect to vestibular ototoxicity. 2. LLL therapy in combination with ginkgo biloba seems to be worth trying on patients with tinnitus.

A reevaluation of the vestibulo-ocular reflex: new ideas of its purpose, properties, neural substrate, and disorders

NASA Technical Reports Server (NTRS)

Leigh, R. J.; Brandt, T.

1993-01-01

Conventional views of the vestibulo-ocular reflex (VOR) have emphasized testing with caloric stimuli and by passively rotating patients at low frequencies in a chair. The properties of the VOR tested under these conditions differ from the performance of this reflex during the natural function for which it evolved--locomotion. Only the VOR (and not visually mediated eye movements) can cope with the high-frequency angular and linear perturbations of the head that occur during locomotion; this is achieved by generating eye movements at short latency (< 16 msec). Interpretation of vestibular testing is enhanced by the realization that, although the di- and trisynaptic components of the VOR are essential for this short-latency response, the overall accuracy and plasticity of the VOR depend upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously upon a distributed, parallel network of neurons involving the vestibular nuclei. Neurons in this network variously encode inputs from the labyrinthine semicircular canals and otoliths, as well as from the visual and somatosensory systems. The central vestibular pathways branch to contact vestibular cortex (for perception) and the spinal cord (for control of posture). Thus, the vestibular nuclei basically coordinate the stabilization of gaze and posture, and contribute to the perception of verticality and self-motion. Consequently, brainstem disorders that disrupt the VOR cause not just only nystagmus, but also instability of posture (eg, increased fore-aft sway in patients with downbeat nystagmus) and disturbance of spatial orientation (eg, tilt of the subjective visual vertical in Wallenberg's syndrome).

GeneOnEarth: fitting genetic PC plots on the globe.

PubMed

Torres-Sánchez, Sergio; Medina-Medina, Nuria; Gignoux, Chris; Abad-Grau, María M; González-Burchard, Esteban

2013-01-01

Principal component (PC) plots have become widely used to summarize genetic variation of individuals in a sample. The similarity between genetic distance in PC plots and geographical distance has shown to be quite impressive. However, in most situations, individual ancestral origins are not precisely known or they are heterogeneously distributed; hence, they are hardly linked to a geographical area. We have developed GeneOnEarth, a user-friendly web-based tool to help geneticists to understand whether a linear isolation-by-distance model may apply to a genetic data set; thus, genetic distances among a set of individuals resemble geographical distances among their origins. Its main goal is to allow users to first apply a by-view Procrustes method to visually learn whether this model holds. To do that, the user can choose the exact geographical area from an on line 2D or 3D world map by using, respectively, Google Maps or Google Earth, and rotate, flip, and resize the images. GeneOnEarth can also compute the optimal rotation angle using Procrustes analysis and assess statistical evidence of similarity when a different rotation angle has been chosen by the user. An online version of GeneOnEarth is available for testing and using purposes at http://bios.ugr.es/GeneOnEarth.

The role of spatial memory and frames of reference in the precision of angular path integration.

PubMed

Arthur, Joeanna C; Philbeck, John W; Kleene, Nicholas J; Chichka, David

2012-09-01

Angular path integration refers to the ability to maintain an estimate of self-location after a rotational displacement by integrating internally-generated (idiothetic) self-motion signals over time. Previous work has found that non-sensory inputs, namely spatial memory, can play a powerful role in angular path integration (Arthur et al., 2007, 2009). Here we investigated the conditions under which spatial memory facilitates angular path integration. We hypothesized that the benefit of spatial memory is particularly likely in spatial updating tasks in which one's self-location estimate is referenced to external space. To test this idea, we administered passive, non-visual body rotations (ranging 40°-140°) about the yaw axis and asked participants to use verbal reports or open-loop manual pointing to indicate the magnitude of the rotation. Prior to some trials, previews of the surrounding environment were given. We found that when participants adopted an egocentric frame of reference, the previously-observed benefit of previews on within-subject response precision was not manifested, regardless of whether remembered spatial frameworks were derived from vision or spatial language. We conclude that the powerful effect of spatial memory is dependent on one's frame of reference during self-motion updating. Copyright © 2012 Elsevier B.V. All rights reserved.

The design of electronic map displays

NASA Technical Reports Server (NTRS)

Aretz, Anthony J.

1991-01-01

This paper presents a cognitive analysis of a pilot's navigation task and describes an experiment comparing a new map display that employs the principle of visual momentum with the two traditional approaches, track-up and north-up. The data show that the advantage of a track-up alignment is its congruence with the egocentered forward view; however, the inconsistency of the rotating display hinders development of a cognitive map. The stability of a north-up alignment aids the acquisition of a cognitive map, but there is a cost associated with the mental rotation of the display to a track-up alignment for tasks involving the ego-centered forward view. The data also show that the visual momentum design captures the benefits and reduces the costs associated with the two traditional approaches.

Changes in muscle directional tuning parallel feedforward adaptation to a visuomotor rotation.

PubMed

de Rugy, Aymar; Carroll, Timothy J

2010-06-01

When people learn to reach in a novel sensorimotor environment, there are changes in the muscle activity required to achieve task goals. Here, we assessed the time course of changes in muscle directional tuning during acquisition of a new mapping between visual information and isometric force production in the absence of feedback-based error corrections. We also measured the influence of visuomotor adaptation on corticospinal excitability, to test whether any changes in muscle directional tuning are associated with adaptations in the final output components of the sensorimotor control system. Nine right-handed subjects performed a ballistic, center-out isometric target acquisition task with the right wrist (16 targets spaced every 22.5 degrees in the joint space). Surface electromyography was recorded from four major wrist muscles, and motor evoked potentials induced by transcranial magnetic stimulation were measured at baseline, after task execution in the absence of the rotation (A1), after adaptation to the rotation (B), and after a final block of trials without rotation (A2). Changes in the directional tuning of muscles closely matched the rotation of the directional error in force, indicating that the functional contribution of muscles remained consistent over the adaptation period. In contrast to previous motor learning studies, we found only minor changes in the amount of muscular activity and no increase in corticospinal excitability. These results suggest that increased muscle co-activation occurs only when the dynamics of the limb are perturbed and/or that online error corrections or altered force requirements are necessary to elicit a component of the adaptation in the final steps of the transformation between motor goal and muscle activation.

Functional Outcome and Healing of Large and Massive Rotator Cuff Tears Repaired With a Load-Sharing Rip-Stop Construct.

PubMed

Noyes, Matthew P; Ladermann, Alexandre; Denard, Patrick J

2017-09-01

To prospectively review functional outcomes and healing rates of large and massive rotator cuff tears repaired with a load-sharing rip-stop (LSRS) technique. Twenty-one consecutive patients underwent arthroscopic rotator cuff repair with an LSRS construct between January and December 2014. Seventeen patients with a minimum of 2 years' follow-up were included. Four patients did not complete clinical evaluations and functional outcome scores at a minimum of 2 years' follow-up and were lost to follow-up. Ultrasound imaging was used to assess for rotator cuff healing at a minimum of 6 months postoperatively. Range of motion, strength, and functional outcome scores were evaluated at final follow-up. Mean active forward elevation improved from 109° preoperatively to 153° postoperatively, and mean supraspinatus strength improved by 1 strength grade, from 3.5 preoperatively to 4.4 postoperatively. When we compared preoperative and postoperative values, the American Shoulder and Elbow Surgeons score improved from 40.8 to 89.5, the Single Assessment Numeric Evaluation score improved from 32.8 to 83.1, the Simple Shoulder Test score improved from 3.8 to 10.3, and the pain score on a visual analog scale decreased from 4.8 to 0.8 (P < .001). Of 17 patients, 13 (82%) were satisfied with their outcomes. Ultrasound evaluation 6 months after surgery showed complete healing in 53%, partial healing in 29%, and no healing in 18%. The LSRS construct showed satisfactory functional outcomes with reasonable healing rates in an otherwise challenging subset of rotator cuff tears. This construct may be an alternative for tears not amenable to double-row repair. Level IV, therapeutic case series. Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Ultrasound evaluation of arthroscopic full-thickness supraspinatus rotator cuff repair: single-row versus double-row suture bridge (transosseous equivalent) fixation. Results of a prospective, randomized study.

PubMed

Gartsman, Gary M; Drake, Gregory; Edwards, T Bradley; Elkousy, Hussein A; Hammerman, Steven M; O'Connor, Daniel P; Press, Cyrus M

2013-11-01

The purpose of this study was to compare the structural outcomes of a single-row rotator cuff repair and double-row suture bridge fixation after arthroscopic repair of a full-thickness supraspinatus rotator cuff tear. We evaluated with diagnostic ultrasound a consecutive series of ninety shoulders in ninety patients with full-thickness supraspinatus tears at an average of 10 months (range, 6-12) after operation. A single surgeon at a single hospital performed the repairs. Inclusion criteria were full-thickness supraspinatus tears less than 25 mm in their anterior to posterior dimension. Exclusion criteria were prior operations on the shoulder, partial thickness tears, subscapularis tears, infraspinatus tears, combined supraspinatus and infraspinatus repairs and irreparable supraspinatus tears. Forty-three shoulders were repaired with single-row technique and 47 shoulders with double-row suture bridge technique. Postoperative rehabilitation was identical for both groups. Ultrasound criteria for healed repair included visualization of a tendon with normal thickness and length, and a negative compression test. Eighty-three patients were available for ultrasound examination (40 single-row and 43 suture-bridge). Thirty of 40 patients (75%) with single-row repair demonstrated a healed rotator cuff repair compared to 40/43 (93%) patients with suture-bridge repair (P = .024). Arthroscopic double-row suture bridge repair (transosseous equivalent) of an isolated supraspinatus rotator cuff tear resulted in a significantly higher tendon healing rate (as determined by ultrasound examination) when compared to arthroscopic single-row repair. Copyright © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

Flexible explicit but rigid implicit learning in a visuomotor adaptation task

PubMed Central

Bond, Krista M.

2015-01-01

There is mounting evidence for the idea that performance in a visuomotor rotation task can be supported by both implicit and explicit forms of learning. The implicit component of learning has been well characterized in previous experiments and is thought to arise from the adaptation of an internal model driven by sensorimotor prediction errors. However, the role of explicit learning is less clear, and previous investigations aimed at characterizing the explicit component have relied on indirect measures such as dual-task manipulations, posttests, and descriptive computational models. To address this problem, we developed a new method for directly assaying explicit learning by having participants verbally report their intended aiming direction on each trial. While our previous research employing this method has demonstrated the possibility of measuring explicit learning over the course of training, it was only tested over a limited scope of manipulations common to visuomotor rotation tasks. In the present study, we sought to better characterize explicit and implicit learning over a wider range of task conditions. We tested how explicit and implicit learning change as a function of the specific visual landmarks used to probe explicit learning, the number of training targets, and the size of the rotation. We found that explicit learning was remarkably flexible, responding appropriately to task demands. In contrast, implicit learning was strikingly rigid, with each task condition producing a similar degree of implicit learning. These results suggest that explicit learning is a fundamental component of motor learning and has been overlooked or conflated in previous visuomotor tasks. PMID:25855690

Beat to beat 3-dimensional intracardiac echocardiography: theoretical approach and practical experiences.

PubMed

Stapf, Daniel; Franke, Andreas; Schreckenberg, Marcus; Schummers, Georg; Mischke, Karl; Marx, Nikolaus; Schauerte, Patrick; Knackstedt, Christian

2013-04-01

Three-dimensional (3D)-imaging provides important information on cardiac anatomy during electrophysiological procedures. Real-time updates of modalities with high soft-tissue contrast are particularly advantageous during cardiac procedures. Therefore, a beat to beat 3D visualization of cardiac anatomy by intracardiac echocardiography (ICE) was developed and tested in phantoms and animals. An electronic phased-array 5-10 MHz ICE-catheter (Acuson, AcuNav/Siemens Medical Solutions USA/64 elements) providing a 90° sector image was used for ICE-imaging. A custom-made mechanical prototype controlled by a servo motor allowed automatic rotation of the ICE-catheter around its longitudinal axis. During a single heartbeat, the ICE-catheter was rotated and 2D-images were acquired. Reconstruction into a 3D volume and rendering by a prototype software was performed beat to beat. After experimental validation using a rigid phantom, the system was tested in an animal study and afterwards, for quantitative validation, in a dynamic phantom. Acquisition of beat to beat 3D-reconstruction was technically feasible. However, twisting of the ICE-catheter shaft due to friction and torsion was found and rotation was hampered. Also, depiction of catheters was not always ensured in case of parallel alignment. Using a curved sheath for depiction of cardiac anatomy there was no congruent depiction of shape and dimension of static and moving objects. Beat to beat 3D-ICE-imaging is feasible. However, shape and dimension of static and moving objects cannot always be displayed with necessary steadiness as needed in the clinical setting. As catheter depiction is also limited, clinical use seems impossible.

Clinical Assessment of Physical Examination Maneuvers for Rotator Cuff Lesions.

PubMed

Somerville, Lyndsay E; Willits, Kevin; Johnson, Andrew M; Litchfield, Robert; LeBel, Marie-Eve; Moro, Jaydeep; Bryant, Dianne

2014-08-01

Shoulder pain and disability pose a diagnostic challenge for clinicians owing to the numerous causes that exist. Unfortunately, the evidence in support of most clinical tests is weak or absent. To determine the diagnostic validity of physical examination maneuvers for rotator cuff lesions. Cohort study (diagnosis); Level of evidence, 1. Consecutive shoulder patients recruited for this study were referred to 2 tertiary orthopaedic clinics. A surgeon took a thorough history and indicated his or her certainty about each possible diagnosis. A clinician performed the physical examination for diagnoses where uncertainty remained. Arthroscopy was considered the reference standard for patients who underwent surgery, and MRI with arthrogram was considered the reference for patients who did not. The sensitivity, specificity, and likelihood ratios were calculated to investigate whether combinations of the top tests provided stronger predictions of the presence or absence of disease. There were 139 participants. None of the tests were highly sensitive for diagnosing rotator cuff tears or tendinosis. Tests for subscapularis tears were all highly specific. No optimal combination of tests improved the ability to correctly diagnose rotator cuff tears. Closer analysis revealed the internal rotation and lateral rotation lag sign did not improve the ability to diagnose subscapularis or supraspinatus tears, respectively, although the lateral rotation lag sign demonstrated a discriminatory ability for tear size. No test in isolation is sufficient to diagnose a patient with rotator cuff damage. A combination of tests improves the ability to diagnose damage to the rotator cuff. It is recommended that the internal rotation and lateral rotation lag signs be removed from the gamut of physical examination tests for supraspinatus and subscapularis tears. © 2014 The Author(s).

Multisensory control of a straight locomotor trajectory.

PubMed

Hanna, Maxim; Fung, Joyce; Lamontagne, Anouk

2017-01-01

Locomotor steering is contingent upon orienting oneself spatially in the environment. When the head is turned while walking, the optic flow projected onto the retina is a complex pattern comprising of a translational and a rotational component. We have created a unique paradigm to simulate different optic flows in a virtual environment. We hypothesized that non-visual (vestibular and somatosensory) cues are required for proper control of a straight trajectory while walking. This research study included 9 healthy young subjects walking in a large physical space (40×25m2) while the virtual environment is viewed in a helmet-mounted display. They were instructed to walk straight in the physical world while being exposed to three conditions: (1) self-initiated active head turns (AHT: 40° right, left, or none); (2) visually simulated head turns (SHT); and (3) visually simulated head turns with no target element (SHT_NT). Conditions 1 and 2 involved an eye-level target which subjects were instructed to fixate, whereas condition 3 was similar to condition 2 but with no target. Identical retinal flow patterns were present in the AHT and SHT conditions whereas non-visual cues differed in that a head rotation was sensed only in AHT but not in SHT. Body motions were captured by a 12-camera Vicon system. Horizontal orientations of the head and body segments, as well as the trajectory of the body's centre of mass were analyzed. SHT and SNT_NT yielded similar results. Heading and body segment orientations changed in the direction opposite to the head turns in SHT conditions. Heading remained unchanged across head turn directions in AHT. Results suggest that non-visual information is used in the control of heading while being exposed to changing rotational optic flows. The small magnitude of the changes in SHT conditions suggests that the CNS can re-weight relevant sources of information to minimize heading errors in the presence of sensory conflicts.

Rotation Reveals the Importance of Configural Cues in Handwritten Word Perception

PubMed Central

Barnhart, Anthony S.; Goldinger, Stephen D.

2013-01-01

A dramatic perceptual asymmetry occurs when handwritten words are rotated 90° in either direction. Those rotated in a direction consistent with their natural tilt (typically clockwise) become much more difficult to recognize, relative to those rotated in the opposite direction. In Experiment 1, we compared computer-printed and handwritten words, all equated for degrees of leftward and rightward tilt, and verified the phenomenon: The effect of rotation was far larger for cursive words, especially when rotated in a tilt-consistent direction. In Experiment 2, we replicated this pattern with all items presented in visual noise. In both experiments, word frequency effects were larger for computer-printed words and did not interact with rotation. The results suggest that handwritten word perception requires greater configural processing, relative to computer print, because handwritten letters are variable and ambiguous. When words are rotated, configural processing suffers, particularly when rotation exaggerates natural tilt. Our account is similar to theories of the “Thatcher Illusion,” wherein face inversion disrupts holistic processing. Together, the findings suggest that configural, word-level processing automatically increases when people read handwriting, as letter-level processing becomes less reliable. PMID:23589201

SDSS-IV MaNGA: stellar angular momentum of about 2300 galaxies: unveiling the bimodality of massive galaxy properties

NASA Astrophysics Data System (ADS)

Graham, Mark T.; Cappellari, Michele; Li, Hongyu; Mao, Shude; Bershady, Matthew A.; Bizyaev, Dmitry; Brinkmann, Jonathan; Brownstein, Joel R.; Bundy, Kevin; Drory, Niv; Law, David R.; Pan, Kaike; Thomas, Daniel; Wake, David A.; Weijmans, Anne-Marie; Westfall, Kyle B.; Yan, Renbin

2018-07-01

We measure λ _{R_e}, a proxy for galaxy specific stellar angular momentum within one effective radius, and the ellipticity, ɛ, for about 2300 galaxies of all morphological types observed with integral field spectroscopy as part of the Mapping Nearby Galaxies at Apache Point Observatory survey, the largest such sample to date. We use the (λ _{R_e}, ɛ ) diagram to separate early-type galaxies into fast and slow rotators. We also visually classify each galaxy according to its optical morphology and two-dimensional stellar velocity field. Comparing these classifications to quantitative λ _{R_e} measurements reveals tight relationships between angular momentum and galaxy structure. In order to account for atmospheric seeing, we use realistic models of galaxy kinematics to derive a general approximate analytic correction for λ _{R_e}. Thanks to the size of the sample and the large number of massive galaxies, we unambiguously detect a clear bimodality in the (λ _{R_e}, ɛ ) diagram which may result from fundamental differences in galaxy assembly history. There is a sharp secondary density peak inside the region of the diagram with low λ _{R_e} and ɛ < 0.4, previously suggested as the definition for slow rotators. Most of these galaxies are visually classified as non-regular rotators and have high velocity dispersion. The intrinsic bimodality must be stronger, as it tends to be smoothed by noise and inclination. The large sample of slow rotators allows us for the first time to unveil a secondary peak at ±90° in their distribution of the misalignments between the photometric and kinematic position angles. We confirm that genuine slow rotators start appearing above M ≥ 2 × 1011 M⊙ where a significant number of high-mass fast rotators also exist.

SDSS-IV MaNGA: Stellar angular momentum of about 2300 galaxies: unveiling the bimodality of massive galaxy properties

NASA Astrophysics Data System (ADS)

Graham, Mark T.; Cappellari, Michele; Li, Hongyu; Mao, Shude; Bershady, Matthew; Bizyaev, Dmitry; Brinkmann, Jonathan; Brownstein, Joel R.; Bundy, Kevin; Drory, Niv; Law, David R.; Pan, Kaike; Thomas, Daniel; Wake, David A.; Weijmans, Anne-Marie; Westfall, Kyle B.; Yan, Renbin

2018-03-01

We measure λ _{R_e}, a proxy for galaxy specific stellar angular momentum within one effective radius, and the ellipticity, ɛ, for about 2300 galaxies of all morphological types observed with integral field spectroscopy as part of the MaNGA survey, the largest such sample to date. We use the (λ _{R_e}, ɛ ) diagram to separate early-type galaxies into fast and slow rotators. We also visually classify each galaxy according to its optical morphology and two-dimensional stellar velocity field. Comparing these classifications to quantitative λ _{R_e} measurements reveals tight relationships between angular momentum and galaxy structure. In order to account for atmospheric seeing, we use realistic models of galaxy kinematics to derive a general approximate analytic correction for λ _{R_e}. Thanks to the size of the sample and the large number of massive galaxies, we unambiguously detect a clear bimodality in the (λ _{R_e}, ɛ ) diagram which may result from fundamental differences in galaxy assembly history. There is a sharp secondary density peak inside the region of the diagram with low λ _{R_e} and ɛ < 0.4, previously suggested as the definition for slow rotators. Most of these galaxies are visually classified as non-regular rotators and have high velocity dispersion. The intrinsic bimodality must be stronger, as it tends to be smoothed by noise and inclination. The large sample of slow rotators allows us for the first time to unveil a secondary peak at ±90○ in their distribution of the misalignments between the photometric and kinematic position angles. We confirm that genuine slow rotators start appearing above M ≥ 2 × 1011M⊙ where a significant number of high-mass fast rotators also exist.

A CAD/CAE analysis of photographic and engineering data

NASA Technical Reports Server (NTRS)

Goza, S. Michael; Peterson, Wayne L.

1987-01-01

In the investigation of the STS 51L accident, NASA engineers were given the task of visual analysis of photographic data extracted from the tracking cameras located at the launch pad. An analysis of the rotations associated with the right Solid Rocket Booster (SRB) was also performed. The visual analysis involved pinpointing coordinates of specific areas on the photographs. The objective of the analysis on the right SRB was to duplicate the rotations provided by the SRB rate gyros and to determine the effects of the rotations on the launch configuration. To accomplish the objectives, computer aided design and engineering was employed. The solid modeler, GEOMOD, inside the Structural Dynamics Research Corp. I-DEAS package, proved invaluable. The problem areas that were encountered and the corresponding solutions that were obtained are discussed. A brief description detailing the construction of the computer generated solid model of the STS launch configuration is given. A discussion of the coordinate systems used in the analysis is provided for the purpose of positioning the model in coordinate space. The techniques and theory used in the model analysis are described.

Development and evaluation of a new 3-D digitization and computer graphic system to study the anatomic tissue and restoration surfaces.

PubMed

Dastane, A; Vaidyanathan, T K; Vaidyanathan, J; Mehra, R; Hesby, R

1996-01-01

It is necessary to visualize and reconstruct tissue anatomic surfaces accurately for a variety of oral rehabilitation applications such as surface wear characterization and automated fabrication of dental restorations, accuracy of reproduction of impression and die materials, etc. In this investigation, a 3-D digitization and computer-graphic system was developed for surface characterization. The hardware consists of a profiler assembly for digitization in an MTS biomechanical test system with an artificial mouth, an IBM PS/2 computer model 70 for data processing and a Hewlett-Packard laser printer for hardcopy outputs. The software used includes a commercially available Surfer 3-D graphics package, a public domain data-fitting alignment software and an inhouse Pascal program for intercommunication plus some other limited tasks. Surfaces were digitized before and after rotation by angular displacement, the digital data were interpolated by Surfer to provide a data grid and the surfaces were computer graphically reconstructed: Misaligned surfaces were aligned by the data-fitting alignment software under different choices of parameters. The effect of different interpolation parameters (e.g. grid size, method of interpolation) and extent of rotation on the alignment accuracy was determined. The results indicate that improved alignment accuracy results from optimization of interpolation parameters and minimization of the initial misorientation between the digitized surfaces. The method provides important advantages for surface reconstruction and visualization, such as overlay of sequentially generated surfaces and accurate alignment of pairs of surfaces with small misalignment.

Distinct eye movement patterns enhance dynamic visual acuity.

PubMed

Palidis, Dimitrios J; Wyder-Hodge, Pearson A; Fooken, Jolande; Spering, Miriam

2017-01-01

Dynamic visual acuity (DVA) is the ability to resolve fine spatial detail in dynamic objects during head fixation, or in static objects during head or body rotation. This ability is important for many activities such as ball sports, and a close relation has been shown between DVA and sports expertise. DVA tasks involve eye movements, yet, it is unclear which aspects of eye movements contribute to successful performance. Here we examined the relation between DVA and the kinematics of smooth pursuit and saccadic eye movements in a cohort of 23 varsity baseball players. In a computerized dynamic-object DVA test, observers reported the location of the gap in a small Landolt-C ring moving at various speeds while eye movements were recorded. Smooth pursuit kinematics-eye latency, acceleration, velocity gain, position error-and the direction and amplitude of saccadic eye movements were linked to perceptual performance. Results reveal that distinct eye movement patterns-minimizing eye position error, tracking smoothly, and inhibiting reverse saccades-were related to dynamic visual acuity. The close link between eye movement quality and DVA performance has important implications for the development of perceptual training programs to improve DVA.

Distinct eye movement patterns enhance dynamic visual acuity

PubMed Central

Palidis, Dimitrios J.; Wyder-Hodge, Pearson A.; Fooken, Jolande; Spering, Miriam

2017-01-01

Dynamic visual acuity (DVA) is the ability to resolve fine spatial detail in dynamic objects during head fixation, or in static objects during head or body rotation. This ability is important for many activities such as ball sports, and a close relation has been shown between DVA and sports expertise. DVA tasks involve eye movements, yet, it is unclear which aspects of eye movements contribute to successful performance. Here we examined the relation between DVA and the kinematics of smooth pursuit and saccadic eye movements in a cohort of 23 varsity baseball players. In a computerized dynamic-object DVA test, observers reported the location of the gap in a small Landolt-C ring moving at various speeds while eye movements were recorded. Smooth pursuit kinematics—eye latency, acceleration, velocity gain, position error—and the direction and amplitude of saccadic eye movements were linked to perceptual performance. Results reveal that distinct eye movement patterns—minimizing eye position error, tracking smoothly, and inhibiting reverse saccades—were related to dynamic visual acuity. The close link between eye movement quality and DVA performance has important implications for the development of perceptual training programs to improve DVA. PMID:28187157

Cue-recruitment for extrinsic signals after training with low information stimuli.

PubMed

Jain, Anshul; Fuller, Stuart; Backus, Benjamin T

2014-01-01

Cue-recruitment occurs when a previously ineffective signal comes to affect the perceptual appearance of a target object, in a manner similar to the trusted cues with which the signal was put into correlation during training. Jain, Fuller and Backus reported that extrinsic signals, those not carried by the target object itself, were not recruited even after extensive training. However, recent studies have shown that training using weakened trusted cues can facilitate recruitment of intrinsic signals. The current study was designed to examine whether extrinsic signals can be recruited by putting them in correlation with weakened trusted cues. Specifically, we tested whether an extrinsic visual signal, the rotary motion direction of an annulus of random dots, and an extrinsic auditory signal, direction of an auditory pitch glide, can be recruited as cues for the rotation direction of a Necker cube. We found learning, albeit weak, for visual but not for auditory signals. These results extend the generality of the cue-recruitment phenomenon to an extrinsic signal and provide further evidence that the visual system learns to use new signals most quickly when other, long-trusted cues are unavailable or unreliable.

Effects of repeated snowboard exercise in virtual reality with time lags of visual scene behind body rotation on head stability and subjective slalom run performance in healthy young subjects.

PubMed

Wada, Yoshiro; Nishiike, Suetaka; Kitahara, Tadashi; Yamanaka, Toshiaki; Imai, Takao; Ito, Taeko; Sato, Go; Matsuda, Kazunori; Kitamura, Yoshiaki; Takeda, Noriaki

2016-11-01

After repeated snowboard exercises in the virtual reality (VR) world with increasing time lags in trials 3-8, it is suggested that the adaptation to repeated visual-vestibulosomatosensory conflict in the VR world improved dynamic posture control and motor performance in the real world without the development of motion sickness. The VR technology was used and the effects of repeated snowboard exercise examined in the VR world with time lags between visual scene and body rotation on the head stability and slalom run performance during exercise in healthy subjects. Forty-two healthy young subjects participated in the study. After trials 1 and 2 of snowboard exercise in the VR world without time lag, trials 3-8 were conducted with 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 s time lags of the visual scene that the computer creates behind board rotation, respectively. Finally, trial 9 was conducted without time lag. Head linear accelerations and subjective slalom run performance were evaluated. The standard deviations of head linear accelerations in inter-aural direction were significantly increased in trial 8, with a time lag of 0.6 s, but significantly decreased in trial 9 without a time lag, compared with those in trial 2 without a time lag. The subjective scores of slalom run performance were significantly decreased in trial 8, with a time lag of 0.6 s, but significantly increased in trial 9 without a time lag, compared with those in trial 2 without a time lag. Motion sickness was not induced in any subjects.

Clinical and optical intraocular performance of rotationally asymmetric multifocal IOL plate-haptic design versus C-loop haptic design.

PubMed

Alió, Jorge L; Plaza-Puche, Ana B; Javaloy, Jaime; Ayala, María José; Vega-Estrada, Alfredo

2013-04-01

To compare the visual and intraocular optical quality outcomes with different designs of the refractive rotationally asymmetric multifocal intraocular lens (MFIOL) (Lentis Mplus; Oculentis GmbH, Berlin, Germany) with or without capsular tension ring (CTR) implantation. One hundred thirty-five consecutive eyes of 78 patients with cataract (ages 36 to 82 years) were divided into three groups: 43 eyes implanted with the C-Loop haptic design without CTR (C-Loop haptic only group); 47 eyes implanted with the C-Loop haptic design with CTR (C-Loop haptic with CTR group); and 45 eyes implanted with the plate-haptic design (plate-haptic group). Visual acuity, contrast sensitivity, defocus curve, and ocular and intraocular optical quality were evaluated at 3 months postoperatively. Significant differences in the postoperative sphere were found (P = .01), with a more myopic postoperative refraction for the C-Loop haptic only group. No significant differences were detected in photopic and scotopic contrast sensitivity among groups (P ⩾ .05). Significantly better visual acuities were present in the C-Loop haptic with CTR group for the defocus levels of -2.0, -1.5, -1.0, and -0.50 D (P ⩽.03). Statistically significant differences among groups were found in total intraocular root mean square (RMS), high-order intraocular RMS, and intraocular coma-like RMS aberrations (P ⩽.04), with lower values from the plate-haptic group. The plate-haptic design and the C-Loop haptic design with CTR implantation both allow good visual rehabilitation. However, better refractive predictability and intraocular optical quality was obtained with the plate-haptic design without CTR implantation. The plate-haptic design seems to be a better design to support rotational asymmetric MFIOL optics. Copyright 2013, SLACK Incorporated.

Evaluation of Different Power of Near Addition in Two Different Multifocal Intraocular Lenses

PubMed Central

Unsal, Ugur; Baser, Gonen

2016-01-01

Purpose. To compare near, intermediate, and distance vision and quality of vision, when refractive rotational multifocal intraocular lenses with 3.0 diopters or diffractive multifocal intraocular lenses with 2.5 diopters near addition are implanted. Methods. 41 eyes of 41 patients in whom rotational +3.0 diopters near addition IOLs were implanted and 30 eyes of 30 patients in whom diffractive +2.5 diopters near addition IOLs were implanted after cataract surgery were reviewed. Uncorrected and corrected distance visual acuity, intermediate visual acuity, near visual acuity, and patient satisfaction were evaluated 6 months later. Results. The corrected and uncorrected distance visual acuity were the same between both groups (p = 0.50 and p = 0.509, resp.). The uncorrected intermediate and corrected intermediate and near vision acuities were better in the +2.5 near vision added intraocular lens implanted group (p = 0.049, p = 0.005, and p = 0.001, resp.) and the uncorrected near vision acuity was better in the +3.0 near vision added intraocular lens implanted group (p = 0.001). The patient satisfactions of both groups were similar. Conclusion. The +2.5 diopters near addition could be a better choice in younger patients with more distance and intermediate visual requirements (driving, outdoor activities), whereas the + 3.0 diopters should be considered for patients with more near vision correction (reading). PMID:27340560

Vestibular-visual interactions in flight simulators

NASA Technical Reports Server (NTRS)

Clark, B.

1977-01-01

All 139 research papers published under this ten-year program are listed. Experimental work was carried out at the Ames Research Center involving man's sensitivity to rotational acceleration, and psychophysical functioning of the semicircular canals; vestibular-visual interactions and effects of other sensory systems were studied in flight simulator environments. Experiments also dealt with the neurophysiological vestibular functions of animals, and flight management investigations of man-vehicle interactions.

Comparison of shoulder internal rotation test with the elbow flexion test in the diagnosis of cubital tunnel syndrome.

PubMed

Ochi, Kensuke; Horiuchi, Yukio; Tanabe, Aya; Morita, Kozo; Takeda, Kentaro; Ninomiya, Ken

2011-05-01

To compare the shoulder internal rotation test-a new, provocative test-with the elbow flexion test in the diagnosis of cubital tunnel syndrome (CubTS). Twenty-five patients with CubTS were examined before and after surgery with 10 seconds each of the elbow flexion and shoulder internal rotation tests. Fifty-four asymptomatic individuals and 14 neuropathy patients with a diagnosis other than CubTS were also examined as control cases. For the shoulder internal rotation test, the patient's upper extremity was kept at 90° abduction, maximum internal rotation, and 10° flexion at the shoulder, with 90° elbow flexion and neutral position of the forearm and wrist, with finger extension. Test results were considered positive if any slight symptom attributable to CubTS occurred within 10 seconds. Extraneural pressure inside the cubital tunnel was intraoperatively measured with the positions of both the elbow flexion and shoulder internal rotation tests, in 15 of the CubTS cases. Statistical analyses were performed using Student's t-test with a confidence level of 95%. The preoperative sensitivity in CubTS cases was 80% in the 10-second shoulder internal rotation test and 36% in the 10-second elbow flexion test, and these differences were significant. None of the control cases had positive results in either test. All the CubTS cases improved with surgery; after surgery, neither test provoked symptoms in any surgical patient. The extraneural pressure increased in both provocative positions with no significant difference. Positive results for the 10-second shoulder internal rotation test were more sensitive than that for the elbow flexion test of the same duration and seemed specific to CubTS. Copyright © 2011 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

How to avoid simulation sickness in virtual environments during user displacement

NASA Astrophysics Data System (ADS)

Kemeny, A.; Colombet, F.; Denoual, T.

2015-03-01

Driving simulation (DS) and Virtual Reality (VR) share the same technologies for visualization and 3D vision and may use the same technics for head movement tracking. They experience also similar difficulties when rendering the displacements of the observer in virtual environments, especially when these displacements are carried out using driver commands, including steering wheels, joysticks and nomad devices. High values for transport delay, the time lag between the action and the corresponding rendering cues and/or visual-vestibular conflict, due to the discrepancies perceived by the human visual and vestibular systems when driving or displacing using a control device, induces the so-called simulation sickness. While the visual transport delay can be efficiently reduced using high frequency frame rate, the visual-vestibular conflict is inherent to VR, when not using motion platforms. In order to study the impact of displacements on simulation sickness, we have tested various driving scenarios in Renault's 5-sided ultra-high resolution CAVE. First results indicate that low speed displacements with longitudinal and lateral accelerations under a given perception thresholds are well accepted by a large number of users and relatively high values are only accepted by experienced users and induce VR induced symptoms and effects (VRISE) for novice users, with a worst case scenario corresponding to rotational displacements. These results will be used for optimization technics at Arts et Métiers ParisTech for motion sickness reduction in virtual environments for industrial, research, educational or gaming applications.

From Foreground to Background: How Task-Neutral Context Influences Contextual Cueing of Visual Search.

PubMed

Zang, Xuelian; Geyer, Thomas; Assumpção, Leonardo; Müller, Hermann J; Shi, Zhuanghua

2016-01-01

Selective attention determines the effectiveness of implicit contextual learning (e.g., Jiang and Leung, 2005). Visual foreground-background segmentation, on the other hand, is a key process in the guidance of attention (Wolfe, 2003). In the present study, we examined the impact of foreground-background segmentation on contextual cueing of visual search in three experiments. A visual search display, consisting of distractor 'L's and a target 'T', was overlaid on a task-neutral cuboid on the same depth plane (Experiment 1), on stereoscopically separated depth planes (Experiment 2), or spread over the entire display on the same depth plane (Experiment 3). Half of the search displays contained repeated target-distractor arrangements, whereas the other half was always newly generated. The task-neutral cuboid was constant during an initial training session, but was either rotated by 90° or entirely removed in the subsequent test sessions. We found that the gains resulting from repeated presentation of display arrangements during training (i.e., contextual-cueing effects) were diminished when the cuboid was changed or removed in Experiment 1, but remained intact in Experiments 2 and 3 when the cuboid was placed in a different depth plane, or when the items were randomly spread over the whole display but not on the edges of the cuboid. These findings suggest that foreground-background segmentation occurs prior to contextual learning, and only objects/arrangements that are grouped as foreground are learned over the course of repeated visual search.

From Foreground to Background: How Task-Neutral Context Influences Contextual Cueing of Visual Search

PubMed Central

Zang, Xuelian; Geyer, Thomas; Assumpção, Leonardo; Müller, Hermann J.; Shi, Zhuanghua

2016-01-01

Selective attention determines the effectiveness of implicit contextual learning (e.g., Jiang and Leung, 2005). Visual foreground-background segmentation, on the other hand, is a key process in the guidance of attention (Wolfe, 2003). In the present study, we examined the impact of foreground-background segmentation on contextual cueing of visual search in three experiments. A visual search display, consisting of distractor ‘L’s and a target ‘T’, was overlaid on a task-neutral cuboid on the same depth plane (Experiment 1), on stereoscopically separated depth planes (Experiment 2), or spread over the entire display on the same depth plane (Experiment 3). Half of the search displays contained repeated target-distractor arrangements, whereas the other half was always newly generated. The task-neutral cuboid was constant during an initial training session, but was either rotated by 90° or entirely removed in the subsequent test sessions. We found that the gains resulting from repeated presentation of display arrangements during training (i.e., contextual-cueing effects) were diminished when the cuboid was changed or removed in Experiment 1, but remained intact in Experiments 2 and 3 when the cuboid was placed in a different depth plane, or when the items were randomly spread over the whole display but not on the edges of the cuboid. These findings suggest that foreground-background segmentation occurs prior to contextual learning, and only objects/arrangements that are grouped as foreground are learned over the course of repeated visual search. PMID:27375530

The Rotator Interval – A Link Between Anatomy and Ultrasound

PubMed Central

Tamborrini, Giorgio; Möller, Ingrid; Bong, David; Miguel, Maribel; Marx, Christian; Müller, Andreas Marc; Müller-Gerbl, Magdalena

2017-01-01

Shoulder pathologies of the rotator cuff of the shoulder are common in clinical practice. The focus of this pictorial essay is to discuss the anatomical details of the rotator interval of the shoulder, correlate the anatomy with normal ultrasound images and present selected pathologies. We focus on the imaging of the rotator interval that is actually the anterosuperior aspect of the glenohumeral joint capsule that is reinforced externally by the coracohumeral ligament, internally by the superior glenohumeral ligament and capsular fibers which blend together and insert medially and laterally to the bicipital groove. In this article we demonstrate the capability of high-resolution musculoskeletal ultrasound to visualize the detailed anatomy of the rotator interval. MSUS has a higher spatial resolution than other imaging techniques and the ability to examine these structures dynamically and to utilize the probe for precise anatomic localization of the patient’s pain by sono-palpation. PMID:28845477

The Rotator Interval - A Link Between Anatomy and Ultrasound.

PubMed

Tamborrini, Giorgio; Möller, Ingrid; Bong, David; Miguel, Maribel; Marx, Christian; Müller, Andreas Marc; Müller-Gerbl, Magdalena

2017-06-01

Shoulder pathologies of the rotator cuff of the shoulder are common in clinical practice. The focus of this pictorial essay is to discuss the anatomical details of the rotator interval of the shoulder, correlate the anatomy with normal ultrasound images and present selected pathologies. We focus on the imaging of the rotator interval that is actually the anterosuperior aspect of the glenohumeral joint capsule that is reinforced externally by the coracohumeral ligament, internally by the superior glenohumeral ligament and capsular fibers which blend together and insert medially and laterally to the bicipital groove. In this article we demonstrate the capability of high-resolution musculoskeletal ultrasound to visualize the detailed anatomy of the rotator interval. MSUS has a higher spatial resolution than other imaging techniques and the ability to examine these structures dynamically and to utilize the probe for precise anatomic localization of the patient's pain by sono-palpation.

Surface acoustic wave micromotor with arbitrary axis rotational capability

NASA Astrophysics Data System (ADS)

Tjeung, Ricky T.; Hughes, Mark S.; Yeo, Leslie Y.; Friend, James R.

2011-11-01

A surface acoustic wave (SAW) actuated rotary motor is reported here, consisting of a millimeter-sized spherical metal rotor placed on the surface of a lead zirconate titanate piezoelectric substrate upon which the SAW is made to propagate. At the design frequency of 3.2 MHz and with a fixed preload of 41.1 μN, the maximum rotational speed and torque achieved were approximately 1900 rpm and 5.37 μN-mm, respectively, producing a maximum output power of 1.19 μW. The surface vibrations were visualized using laser Doppler vibrometry and indicate that the rotational motion arises due to retrograde elliptical motions of the piezoelectric surface elements. Rotation about orthogonal axes in the plane of the substrate has been obtained by using orthogonally placed interdigital electrodes on the substrate to generate SAW impinging on the rotor, offering a means to generate rotation about an arbitrary axis in the plane of the substrate.

Rotation of endosomes demonstrates coordination of molecular motors during axonal transport.

PubMed

Kaplan, Luke; Ierokomos, Athena; Chowdary, Praveen; Bryant, Zev; Cui, Bianxiao

2018-03-01

Long-distance axonal transport is critical to the maintenance and function of neurons. Robust transport is ensured by the coordinated activities of multiple molecular motors acting in a team. Conventional live-cell imaging techniques used in axonal transport studies detect this activity by visualizing the translational dynamics of a cargo. However, translational measurements are insensitive to torques induced by motor activities. By using gold nanorods and multichannel polarization microscopy, we simultaneously measure the rotational and translational dynamics for thousands of axonally transported endosomes. We find that the rotational dynamics of an endosome provide complementary information regarding molecular motor activities to the conventionally tracked translational dynamics. Rotational dynamics correlate with translational dynamics, particularly in cases of increased rotation after switches between kinesin- and dynein-mediated transport. Furthermore, unambiguous measurement of nanorod angle shows that endosome-contained nanorods align with the orientation of microtubules, suggesting a direct mechanical linkage between the ligand-receptor complex and the microtubule motors.

Effects of object asymmetry on visual attention.

PubMed

Maguire, Anne M; Bates, Timothy C; Boycott, Noël; Corballis, Michael C

2002-01-01

Unilateral neglect has been demonstrated relative to the intrinsic left side of objects, even when presented in the preserved hemispace. These results have been interpreted as evidence of an object-centered reference frame. In the present study, neurologically normal individuals were presented with letter stimuli having distinguishing features to the right (R) or left (J) of their intrinsic midline, shown in normal and mirror parity, and in six angle rotations. RTs confirmed that participants rotated the letters to the upright to decide parity: such rotation would align the object-centered and viewer-centered frames of reference, suggesting that not controlling for mental rotation would confound this effect. In addition, a dot, presented lateral to the main letter stimulus, resulted in quicker parity decisions when on the maximally-informative side of the letter. Together, the results suggest that apparent object-centered neglect may arise from the combined effects of mental rotation and within-object information asymmetries.

Rotational and Translational Components of Motion Parallax: Observers' Sensitivity and Implications for Three-Dimensional Computer Graphics

NASA Technical Reports Server (NTRS)

Kaiser, Mary K.; Montegut, Michael J.; Proffitt, Dennis R.

1995-01-01

The motion of objects during motion parallax can be decomposed into 2 observer-relative components: translation and rotation. The depth ratio of objects in the visual field is specified by the inverse ratio of their angular displacement (from translation) or equivalently by the inverse ratio of their rotations. Despite the equal mathematical status of these 2 information sources, it was predicted that observers would be far more sensitive to the translational than rotational component. Such a differential sensitivity is implicitly assumed by the computer graphics technique billboarding, in which 3-dimensional (3-D) objects are drawn as planar forms (i.e., billboards) maintained normal to the line of sight. In 3 experiments, observers were found to be consistently less sensitive to rotational anomalies. The implications of these findings for kinetic depth effect displays and billboarding techniques are discussed.

FAR and NEAR Target Dynamic Visual Acuity: A Functional Assessment of Canal and Otolith Performance

NASA Technical Reports Server (NTRS)

Peters, Brian T.; Brady, Rachel A.; Landsness, Eric C.; Black, F. Owen; Bloomberg, Jacob J.

2004-01-01

Upon their return to earth, astronauts experience the effects of vestibular adaptation to microgravity. The postflight changes in vestibular information processing can affect postural and locomotor stability and may lead to oscillopsia during activities of daily living. However, it is likely that time spent in microgravity affects canal and otolith function differently. As a result, the isolated rotational stimuli used in traditional tests of canal function may fail to identify vestibular deficits after spaceflight. Also, the functional consequences of deficits that are identified often remain unknown. In a gaze control task, the relative contributions of the canal and otolith organs are modulated with viewing distance. The ability to stabilize gaze during a perturbation, on visual targets placed at different distances from the head may therefore provide independent insight into the function of this systems. Our goal was to develop a functional measure of gaze control that can also offer independent information about the function of the canal and otolith organs.

Surgical lesion of the anterior optic tract abolishes polarotaxis in tethered flying locusts, Schistocerca gregaria.

PubMed

Mappes, Martina; Homberg, Uwe

2007-01-01

Many insects can detect the polarization pattern of the blue sky and rely on polarization vision for sky compass orientation. In laboratory experiments, tethered flying locusts perform periodic changes in flight behavior under a slowly rotating polarizer even if one eye is painted black. Anatomical tracing studies and intracellular recordings have suggested that the polarization vision pathway in the locust brain involves the anterior optic tract and tubercle, the lateral accessory lobe, and the central complex of the brain. To investigate whether visual pathways through the anterior optic tract mediate polarotaxis in the desert locust, we transected the tract on one side and tested polarotaxis (1) with both eyes unoccluded and (2) with the eye of the intact hemisphere painted black. In the second group of animals, but not in the first group, polarotaxis was abolished. Sham operations did not impair polarotaxis. The experiments show that the anterior optic tract is an indispensable part of visual pathways mediating polarotaxis in the desert locust.

Differences between early-blind, late-blind, and blindfolded-sighted people in haptic spatial-configuration learning and resulting memory traces.

PubMed

Postma, Albert; Zuidhoek, Sander; Noordzij, Matthijs L; Kappers, Astrid M L

2007-01-01

The roles of visual and haptic experience in different aspects of haptic processing of objects in peripersonal space are examined. In three trials, early-blind, late-blind, and blindfolded-sighted individuals had to match ten shapes haptically to the cut-outs in a board as fast as possible. Both blind groups were much faster than the sighted in all three trials. All three groups improved considerably from trial to trial. In particular, the sighted group showed a strong improvement from the first to the second trial. While superiority of the blind remained for speeded matching after rotation of the stimulus frame, coordinate positional-memory scores in a non-speeded free-recall trial showed no significant differences between the groups. Moreover, when assessed with a verbal response, categorical spatial-memory appeared strongest in the late-blind group. The role of haptic and visual experience thus appears to depend on the task aspect tested.

Rotation invariants of vector fields from orthogonal moments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Bo; Kostková, Jitka; Flusser, Jan

Vector field images are a type of new multidimensional data that appear in many engineering areas. Although the vector fields can be visualized as images, they differ from graylevel and color images in several aspects. In order to analyze them, special methods and algorithms must be originally developed or substantially adapted from the traditional image processing area. Here, we propose a method for the description and matching of vector field patterns under an unknown rotation of the field. Rotation of a vector field is so-called total rotation, where the action is applied not only on the spatial coordinates but alsomore » on the field values. Invariants of vector fields with respect to total rotation constructed from orthogonal Gaussian–Hermite moments and Zernike moments are introduced. Their numerical stability is shown to be better than that of the invariants published so far. We demonstrate their usefulness in a real world template matching application of rotated vector fields.« less

Rotation invariants of vector fields from orthogonal moments

DOE PAGES

Yang, Bo; Kostková, Jitka; Flusser, Jan; ...

2017-09-11

Vector field images are a type of new multidimensional data that appear in many engineering areas. Although the vector fields can be visualized as images, they differ from graylevel and color images in several aspects. In order to analyze them, special methods and algorithms must be originally developed or substantially adapted from the traditional image processing area. Here, we propose a method for the description and matching of vector field patterns under an unknown rotation of the field. Rotation of a vector field is so-called total rotation, where the action is applied not only on the spatial coordinates but alsomore » on the field values. Invariants of vector fields with respect to total rotation constructed from orthogonal Gaussian–Hermite moments and Zernike moments are introduced. Their numerical stability is shown to be better than that of the invariants published so far. We demonstrate their usefulness in a real world template matching application of rotated vector fields.« less

Ultrasound-Guided Prolotherapy with Polydeoxyribonucleotide for Painful Rotator Cuff Tendinopathy.

PubMed

Ryu, Kyoungho; Ko, Dongchan; Lim, Goeun; Kim, Eugene; Lee, Sung Hyun

2018-01-01

Rotator cuff tendinopathy is a primary cause of shoulder pain and dysfunction. Several effective nonsurgical treatment methods have been described for chronic rotator cuff tendinopathy. Prolotherapy with polydeoxyribonucleotide (PDRN), which consists of active deoxyribonucleotide polymers that stimulate tissue repair, is a nonsurgical regenerative injection that may be a viable treatment option. The objective of this study was to assess the efficacy of PDRN in the treatment of chronic rotator cuff tendinopathy. The records of patients with chronic rotator cuff tendinopathy ( n =131) were reviewed retrospectively, and the patients treated with PDRN prolotherapy ( n =32) were selected. We measured the main outcome of the shoulder pain and disability index score on a numerical rating scale of average shoulder pain. Compared with baseline data, significant improvements in the shoulder pain and disability index and pain visual analog scale scores were demonstrated at one week after the end of treatment, and at one month and three months later. PDRN prolotherapy may improve the conservative treatment of painful rotator cuff tendinopathy for a specific subset of patients.

Visual attention mediates the relationship between body satisfaction and susceptibility to the body size adaptation effect.

PubMed

Stephen, Ian D; Sturman, Daniel; Stevenson, Richard J; Mond, Jonathan; Brooks, Kevin R

2018-01-01

Body size misperception-the belief that one is larger or smaller than reality-affects a large and growing segment of the population. Recently, studies have shown that exposure to extreme body stimuli results in a shift in the point of subjective normality, suggesting that visual adaptation may be a mechanism by which body size misperception occurs. Yet, despite being exposed to a similar set of bodies, some individuals within a given geographical area will develop body size misperception and others will not. The reason for these individual difference is currently unknown. One possible explanation stems from the observation that women with lower levels of body satisfaction have been found to pay more attention to images of thin bodies. However, while attention has been shown to enhance visual adaptation effects in low (e.g. rotational and linear motion) and high level stimuli (e.g., facial gender), it is not known whether this effect exists in visual adaptation to body size. Here, we test the hypothesis that there is an indirect effect of body satisfaction on the direction and magnitude of the body fat adaptation effect, mediated via visual attention (i.e., selectively attending to images of thin over fat bodies or vice versa). Significant mediation effects were found in both men and women, suggesting that observers' level of body satisfaction may influence selective visual attention to thin or fat bodies, which in turn influences the magnitude and direction of visual adaptation to body size. This may provide a potential mechanism by which some individuals develop body size misperception-a risk factor for eating disorders, compulsive exercise behaviour and steroid abuse-while others do not.

Visual attention mediates the relationship between body satisfaction and susceptibility to the body size adaptation effect

PubMed Central

Sturman, Daniel; Stevenson, Richard J.; Mond, Jonathan; Brooks, Kevin R.

2018-01-01

Body size misperception–the belief that one is larger or smaller than reality–affects a large and growing segment of the population. Recently, studies have shown that exposure to extreme body stimuli results in a shift in the point of subjective normality, suggesting that visual adaptation may be a mechanism by which body size misperception occurs. Yet, despite being exposed to a similar set of bodies, some individuals within a given geographical area will develop body size misperception and others will not. The reason for these individual difference is currently unknown. One possible explanation stems from the observation that women with lower levels of body satisfaction have been found to pay more attention to images of thin bodies. However, while attention has been shown to enhance visual adaptation effects in low (e.g. rotational and linear motion) and high level stimuli (e.g., facial gender), it is not known whether this effect exists in visual adaptation to body size. Here, we test the hypothesis that there is an indirect effect of body satisfaction on the direction and magnitude of the body fat adaptation effect, mediated via visual attention (i.e., selectively attending to images of thin over fat bodies or vice versa). Significant mediation effects were found in both men and women, suggesting that observers’ level of body satisfaction may influence selective visual attention to thin or fat bodies, which in turn influences the magnitude and direction of visual adaptation to body size. This may provide a potential mechanism by which some individuals develop body size misperception–a risk factor for eating disorders, compulsive exercise behaviour and steroid abuse–while others do not. PMID:29385137

Concentric and eccentric torque of the hip musculature in individuals with and without patellofemoral pain.

PubMed

Boling, Michelle C; Padua, Darin A; Alexander Creighton, R

2009-01-01

Individuals suffering from patellofemoral pain have previously been reported to have decreased isometric strength of the hip musculature; however, no researchers have investigated concentric and eccentric torque of the hip musculature in individuals with patellofemoral pain. To compare concentric and eccentric torque of the hip musculature in individuals with and without patellofemoral pain. Case control. Research laboratory. Twenty participants with patellofemoral pain (age = 26.8 +/- 4.5 years, height = 171.8 +/- 8.4 cm, mass = 72.4 +/- 16.8 kg) and 20 control participants (age = 25.6 +/- 2.8 years, height = 169.5 +/- 8.9 cm, mass = 70.0 +/- 16.9 kg) were tested. Volunteers with patellofemoral pain met the following criteria: knee pain greater than or equal to 3 cm on a 10-cm visual analog scale, insidious onset of symptoms not related to trauma, pain with palpation of the patellar facets, and knee pain during 2 of the following activities: stair climbing, jumping or running, squatting, kneeling, or prolonged sitting. Control participants were excluded if they had a prior history of patellofemoral pain, knee surgery in the past 2 years, or current lower extremity injury that limited participation in physical activity. Concentric and eccentric torque of the hip musculature was measured on an isokinetic dynamometer. All volunteers performed 5 repetitions of each strength test. Separate multivariate analyses of variance were performed to compare concentric and eccentric torque of the hip extensors, abductors, and external rotators between groups. Average and peak concentric and eccentric torque of the hip extensors, abductors, and external rotators. Torque measures were normalized to the participant's body weight multiplied by height. The patellofemoral pain group was weaker than the control group for peak eccentric hip abduction torque (F(1,38) = 6.630, P = .014), and average concentric (F(1,38) = 4.156, P = .048) and eccentric (F(1,38) = 4.963, P = .032) hip external rotation torque. The patellofemoral pain group displayed weakness in eccentric hip abduction and hip external rotation, which may allow for increased hip adduction and internal rotation during functional movements.

Which way is up? Asymmetric spectral input along the dorsal-ventral axis influences postural responses in an amphibious annelid.

PubMed

Jellies, John

2014-11-01

Medicinal leeches are predatory annelids that exhibit countershading and reside in aquatic environments where light levels might be variable. They also leave the water and must contend with terrestrial environments. Yet, leeches generally maintain a dorsal upward position despite lacking statocysts. Leeches respond visually to both green and near-ultraviolet (UV) light. I used LEDs to test the hypothesis that ventral, but not dorsal UV would evoke compensatory movements to orient the body. Untethered leeches were tested using LEDs emitting at red (632 nm), green (513 nm), blue (455 nm) and UV (372 nm). UV light evoked responses in 100 % of trials and the leeches often rotated the ventral surface away from it. Visible light evoked no or modest responses (12-15 % of trials) and no body rotation. Electrophysiological recordings showed that ventral sensilla responded best to UV, dorsal sensilla to green. Additionally, a higher order interneuron that is engaged in a variety of parallel networks responded vigorously to UV presented ventrally, and both the visible and UV responses exhibited pronounced light adaptation. These results strongly support the suggestion that a dorsal light reflex in the leech uses spectral comparisons across the dorsal-ventral axis rather than, or in addition to, luminance.

Plastification of polymers in twin-screw-extruders: New visualization technic using high-speed imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knieper, A., E-mail: Alexander.Knieper@lbf.fraunhofer.de, E-mail: Christian.Beinert@lbf.fraunhofer.de; Beinert, C., E-mail: Alexander.Knieper@lbf.fraunhofer.de, E-mail: Christian.Beinert@lbf.fraunhofer.de

The initial melting of the first granules through plastic energy dissipation (PED) at the beginning of the melting zone, in the co-rotating twin-screw extruder is visualized in this work. The visualization was created through the use of a high speed camera in the cross section of the melting zone. The parameters screw speed, granule-temperature, temperature-profile, type of polymer and back pressure were examined. It was shown that the screw speed and the temperature-profile have significant influence on the rate of initial melting.

Cognitive profile of patients with rotated drawing at copy or recall: a controlled group study.

PubMed

Molteni, Federica; Traficante, Debora; Ferri, Francesca; Isella, Valeria

2014-03-01

When copying or recalling a figure from memory, some patient with dementia or focal brain lesions may rotate the drawing through ±90° or 180°. We have tried to clarify the nature of this phenomenon by investigating the cognitive profile of 22 patients who rotated the copy of the Rey-Osterrieth Complex Figure and 27 who rotated (only) the recall, and two control groups of cases with the same neuropsychiatric diagnoses, but no misorientation deficit. Brain MRI and FDG-PET images were also analysed. Predictor of rotation at the copy versus rotation at the recall was visuospatial impairment as measured by the copy of the Rey Figure; predictors of rotation at the copy versus no rotation were, again, visuospatial deficits, in addition to an abnormal performance at the task of selective attention. No specific profile of cognitive impairment distinguished patients with and without rotation at the recall. Disproportionate temporo-parieto-occipital atrophy or hypometabolism were evident in cases with misorientation of the copy, while predominant frontal abnormalities were found in cases of rotated recall. Based on these findings, rotated drawing at the copy is interpreted as a dorsal visual stream deficit, whose occurrence is more probable when attentional control is impaired. Rotation at recall seems to have a distinct, more anterior, neural substrate, but its dysexecutive nature has yet to be demonstrated. Copyright © 2014 Elsevier Inc. All rights reserved.

Medialized repair for retracted rotator cuff tears.

PubMed

Kim, Young-Kyu; Jung, Kyu-Hak; Won, Jun-Sung; Cho, Seung-Hyun

2017-08-01

The purpose of this study was to evaluate the functional outcomes of medialized rotator cuff repair and the continuity of repaired tendon in chronic retracted rotator cuff tears. Thirty-five consecutive patients were selected from 153 cases that underwent arthroscopic rotator cuff repair for more than medium-sized posterosuperior rotator cuff tears between July 2009 and July 2012 performed with the medialized repair. All cases were available for at least 2 years of postoperative follow-up. The visual analog scale of pain, muscle strength, Constant score, American Shoulder and Elbow Surgeons (ASES) score, and University of California-Los Angeles score were evaluated. At the final follow-up, all clinical outcomes were significantly improved. The visual analog scale score for pain improved from 6 ± 1 preoperatively to 2 ± 1 postoperatively. The range of motion increased from preoperatively to postoperatively: active forward elevation, from 134° ± 49° to 150° ± 16°; active external rotation at the side, from 47° ± 15° to 55° ± 10°; and active internal rotation, from L3 to L1. The shoulder score also improved: Constant score, from 53.5 ± 16.7 to 79 ± 10; American Shoulder and Elbow Surgeons score, from 51 ± 15 to 82 ± 8; and University of California-Los Angeles score, from 14 ± 4 to 28 ± 4. The retear cases at the final follow-up were 6 (17%). Medialized repair may be useful in cases in which anatomic bone-to-tendon repair would be difficult because of the excessive tension of the repaired tendon and a torn tendon that does not reach the anatomic insertion. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Enhancing the hydrodynamic performance of a tapered swept-back wing through leading-edge tubercles

NASA Astrophysics Data System (ADS)

Wei, Zhaoyu; Lian, Lian; Zhong, Yisen

2018-06-01

The hydrodynamic benefit of implementing leading-edge (LE) tubercles on wings at very low Reynolds numbers ( Res) has not been thoroughly elucidated to date, though their benefits at relatively higher Res are well-studied. Through wind tunnel testing at Re = 5.5 × 104, we found that the LE tubercles increase the lift at all pitch angles tested and slightly reduce the drag at a pitch angle of 4° < α < 10°, which finally results in a significant hydrodynamic performance enhancement at lower pitch angles. Flow visualization reveals that the hydrodynamic performance enhancement is due to the favourable attached flows downstream of the tubercle peaks. The attached flows are believed to be closely related to the downwash and momentum exchange within the boundary layers, which originate from surface and streamwise-aligned counter-rotating vortex pairs (CVPs).

Dissociating object-based from egocentric transformations in mental body rotation: effect of stimuli size.

PubMed

Habacha, Hamdi; Moreau, David; Jarraya, Mohamed; Lejeune-Poutrain, Laure; Molinaro, Corinne

2018-01-01

The effect of stimuli size on the mental rotation of abstract objects has been extensively investigated, yet its effect on the mental rotation of bodily stimuli remains largely unexplored. Depending on the experimental design, mentally rotating bodily stimuli can elicit object-based transformations, relying mainly on visual processes, or egocentric transformations, which typically involve embodied motor processes. The present study included two mental body rotation tasks requiring either a same-different or a laterality judgment, designed to elicit object-based or egocentric transformations, respectively. Our findings revealed shorter response times for large-sized stimuli than for small-sized stimuli only for greater angular disparities, suggesting that the more unfamiliar the orientations of the bodily stimuli, the more stimuli size affected mental processing. Importantly, when comparing size transformation times, results revealed different patterns of size transformation times as a function of angular disparity between object-based and egocentric transformations. This indicates that mental size transformation and mental rotation proceed differently depending on the mental rotation strategy used. These findings are discussed with respect to the different spatial manipulations involved during object-based and egocentric transformations.