Measuring Human Performance in Simulated Nuclear Power Plant Control Rooms Using Eye Tracking

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

Kovesdi, Casey Robert; Rice, Brandon Charles; Bower, Gordon Ross

Control room modernization will be an important part of life extension for the existing light water reactor fleet. As part of modernization efforts, personnel will need to gain a full understanding of how control room technologies affect performance of human operators. Recent advances in technology enables the use of eye tracking technology to continuously measure an operator’s eye movement, which correlates with a variety of human performance constructs such as situation awareness and workload. This report describes eye tracking metrics in the context of how they will be used in nuclear power plant control room simulator studies.

Precise Head Tracking in Hearing Applications

NASA Astrophysics Data System (ADS)

Helle, A. M.; Pilinski, J.; Luhmann, T.

2015-05-01

The paper gives an overview about two research projects, both dealing with optical head tracking in hearing applications. As part of the project "Development of a real-time low-cost tracking system for medical and audiological problems (ELCoT)" a cost-effective single camera 3D tracking system has been developed which enables the detection of arm and head movements of human patients. Amongst others, the measuring system is designed for a new hearing test (based on the "Mainzer Kindertisch"), which analyzes the directional hearing capabilities of children in cooperation with the research project ERKI (Evaluation of acoustic sound source localization for children). As part of the research project framework "Hearing in everyday life (HALLO)" a stereo tracking system is being used for analyzing the head movement of human patients during complex acoustic events. Together with the consideration of biosignals like skin conductance the speech comprehension and listening effort of persons with reduced hearing ability, especially in situations with background noise, is evaluated. For both projects the system design, accuracy aspects and results of practical tests are discussed.

Exploring responses to art in adolescence: a behavioral and eye-tracking study.

PubMed

Savazzi, Federica; Massaro, Davide; Di Dio, Cinzia; Gallese, Vittorio; Gilli, Gabriella; Marchetti, Antonella

2014-01-01

Adolescence is a peculiar age mainly characterized by physical and psychological changes that may affect the perception of one's own and others' body. This perceptual peculiarity may influence the way in which bottom-up and top-down processes interact and, consequently, the perception and evaluation of art. This study is aimed at investigating, by means of the eye-tracking technique, the visual explorative behavior of adolescents while looking at paintings. Sixteen color paintings, categorized as dynamic and static, were presented to twenty adolescents; half of the images represented natural environments and half human individuals; all stimuli were displayed under aesthetic and movement judgment tasks. Participants' ratings revealed that, generally, nature images are explicitly evaluated as more appealing than human images. Eye movement data, on the other hand, showed that the human body exerts a strong power in orienting and attracting visual attention and that, in adolescence, it plays a fundamental role during aesthetic experience. In particular, adolescents seem to approach human-content images by giving priority to elements calling forth movement and action, supporting the embodiment theory of aesthetic perception.

Exploring Responses to Art in Adolescence: A Behavioral and Eye-Tracking Study

PubMed Central

Savazzi, Federica; Massaro, Davide; Di Dio, Cinzia; Gallese, Vittorio; Gilli, Gabriella; Marchetti, Antonella

2014-01-01

Adolescence is a peculiar age mainly characterized by physical and psychological changes that may affect the perception of one's own and others' body. This perceptual peculiarity may influence the way in which bottom-up and top-down processes interact and, consequently, the perception and evaluation of art. This study is aimed at investigating, by means of the eye-tracking technique, the visual explorative behavior of adolescents while looking at paintings. Sixteen color paintings, categorized as dynamic and static, were presented to twenty adolescents; half of the images represented natural environments and half human individuals; all stimuli were displayed under aesthetic and movement judgment tasks. Participants' ratings revealed that, generally, nature images are explicitly evaluated as more appealing than human images. Eye movement data, on the other hand, showed that the human body exerts a strong power in orienting and attracting visual attention and that, in adolescence, it plays a fundamental role during aesthetic experience. In particular, adolescents seem to approach human-content images by giving priority to elements calling forth movement and action, supporting the embodiment theory of aesthetic perception. PMID:25048813

SwarmSight: Real-time Tracking of Insect Antenna Movements and Proboscis Extension Reflex Using a Common Preparation and Conventional Hardware

PubMed Central

Birgiolas, Justas; Jernigan, Christopher M.; Gerkin, Richard C.; Smith, Brian H.; Crook, Sharon M.

2017-01-01

Many scientifically and agriculturally important insects use antennae to detect the presence of volatile chemical compounds and extend their proboscis during feeding. The ability to rapidly obtain high-resolution measurements of natural antenna and proboscis movements and assess how they change in response to chemical, developmental, and genetic manipulations can aid the understanding of insect behavior. By extending our previous work on assessing aggregate insect swarm or animal group movements from natural and laboratory videos using the video analysis software SwarmSight, we developed a novel, free, and open-source software module, SwarmSight Appendage Tracking (SwarmSight.org) for frame-by-frame tracking of insect antenna and proboscis positions from conventional web camera videos using conventional computers. The software processes frames about 120 times faster than humans, performs at better than human accuracy, and, using 30 frames per second (fps) videos, can capture antennal dynamics up to 15 Hz. The software was used to track the antennal response of honey bees to two odors and found significant mean antennal retractions away from the odor source about 1 s after odor presentation. We observed antenna position density heat map cluster formation and cluster and mean angle dependence on odor concentration. PMID:29364251

Usefulness of commercially available GPS data-loggers for tracking human movement and exposure to dengue virus

PubMed Central

2009-01-01

Background Our understanding of the effects of human movement on dengue virus spread remains limited in part due to the lack of precise tools to monitor the time-dependent location of individuals. We determined the utility of a new, commercially available, GPS data-logger for long-term tracking of human movements in Iquitos, Peru. We conducted a series of evaluations focused on GPS device attributes key to reliable use and accuracy. GPS observations from two participants were later compared with semi-structured interview data to assess the usefulness of GPS technology to track individual mobility patterns. Results Positional point and line accuracy were 4.4 and 10.3 m, respectively. GPS wearing mode increased spatial point error by 6.9 m. Units were worn on a neck-strap by a carpenter and a moto-taxi driver for 14-16 days. The application of a clustering algorithm (I-cluster) to the raw GPS positional data allowed the identification of locations visited by each participant together with the frequency and duration of each visit. The carpenter moved less and spent more time in more fixed locations than the moto-taxi driver, who visited more locations for a shorter period of time. GPS and participants' interviews concordantly identified 6 common locations, whereas GPS alone identified 4 locations and participants alone identified 10 locations. Most (80%) of the locations identified by participants alone were places reported as visited for less than 30 minutes. Conclusion The present study demonstrates the feasibility of a novel, commercially available GPS data-logger for long-term tracking of humans and shows the potential of these units to quantify mobility patterns in relationship with dengue virus transmission risk in a tropical urban environment. Cost, battery life, size, programmability and ease of wear are unprecedented from previously tested units, proving the usefulness of GPS-dataloggers for linking movement of individuals and transmission risk of dengue virus and other infectious agents, particularly in resource-poor settings. PMID:19948034

Usefulness of commercially available GPS data-loggers for tracking human movement and exposure to dengue virus.

PubMed

Vazquez-Prokopec, Gonzalo M; Stoddard, Steven T; Paz-Soldan, Valerie; Morrison, Amy C; Elder, John P; Kochel, Tadeusz J; Scott, Thomas W; Kitron, Uriel

2009-11-30

Our understanding of the effects of human movement on dengue virus spread remains limited in part due to the lack of precise tools to monitor the time-dependent location of individuals. We determined the utility of a new, commercially available, GPS data-logger for long-term tracking of human movements in Iquitos, Peru. We conducted a series of evaluations focused on GPS device attributes key to reliable use and accuracy. GPS observations from two participants were later compared with semi-structured interview data to assess the usefulness of GPS technology to track individual mobility patterns. Positional point and line accuracy were 4.4 and 10.3 m, respectively. GPS wearing mode increased spatial point error by 6.9 m. Units were worn on a neck-strap by a carpenter and a moto-taxi driver for 14-16 days. The application of a clustering algorithm (I-cluster) to the raw GPS positional data allowed the identification of locations visited by each participant together with the frequency and duration of each visit. The carpenter moved less and spent more time in more fixed locations than the moto-taxi driver, who visited more locations for a shorter period of time. GPS and participants' interviews concordantly identified 6 common locations, whereas GPS alone identified 4 locations and participants alone identified 10 locations. Most (80%) of the locations identified by participants alone were places reported as visited for less than 30 minutes. The present study demonstrates the feasibility of a novel, commercially available GPS data-logger for long-term tracking of humans and shows the potential of these units to quantify mobility patterns in relationship with dengue virus transmission risk in a tropical urban environment. Cost, battery life, size, programmability and ease of wear are unprecedented from previously tested units, proving the usefulness of GPS-dataloggers for linking movement of individuals and transmission risk of dengue virus and other infectious agents, particularly in resource-poor settings.

Moving in the Anthropocene: Global reductions in terrestrial mammalian movements.

PubMed

Tucker, Marlee A; Böhning-Gaese, Katrin; Fagan, William F; Fryxell, John M; Van Moorter, Bram; Alberts, Susan C; Ali, Abdullahi H; Allen, Andrew M; Attias, Nina; Avgar, Tal; Bartlam-Brooks, Hattie; Bayarbaatar, Buuveibaatar; Belant, Jerrold L; Bertassoni, Alessandra; Beyer, Dean; Bidner, Laura; van Beest, Floris M; Blake, Stephen; Blaum, Niels; Bracis, Chloe; Brown, Danielle; de Bruyn, P J Nico; Cagnacci, Francesca; Calabrese, Justin M; Camilo-Alves, Constança; Chamaillé-Jammes, Simon; Chiaradia, Andre; Davidson, Sarah C; Dennis, Todd; DeStefano, Stephen; Diefenbach, Duane; Douglas-Hamilton, Iain; Fennessy, Julian; Fichtel, Claudia; Fiedler, Wolfgang; Fischer, Christina; Fischhoff, Ilya; Fleming, Christen H; Ford, Adam T; Fritz, Susanne A; Gehr, Benedikt; Goheen, Jacob R; Gurarie, Eliezer; Hebblewhite, Mark; Heurich, Marco; Hewison, A J Mark; Hof, Christian; Hurme, Edward; Isbell, Lynne A; Janssen, René; Jeltsch, Florian; Kaczensky, Petra; Kane, Adam; Kappeler, Peter M; Kauffman, Matthew; Kays, Roland; Kimuyu, Duncan; Koch, Flavia; Kranstauber, Bart; LaPoint, Scott; Leimgruber, Peter; Linnell, John D C; López-López, Pascual; Markham, A Catherine; Mattisson, Jenny; Medici, Emilia Patricia; Mellone, Ugo; Merrill, Evelyn; de Miranda Mourão, Guilherme; Morato, Ronaldo G; Morellet, Nicolas; Morrison, Thomas A; Díaz-Muñoz, Samuel L; Mysterud, Atle; Nandintsetseg, Dejid; Nathan, Ran; Niamir, Aidin; Odden, John; O'Hara, Robert B; Oliveira-Santos, Luiz Gustavo R; Olson, Kirk A; Patterson, Bruce D; Cunha de Paula, Rogerio; Pedrotti, Luca; Reineking, Björn; Rimmler, Martin; Rogers, Tracey L; Rolandsen, Christer Moe; Rosenberry, Christopher S; Rubenstein, Daniel I; Safi, Kamran; Saïd, Sonia; Sapir, Nir; Sawyer, Hall; Schmidt, Niels Martin; Selva, Nuria; Sergiel, Agnieszka; Shiilegdamba, Enkhtuvshin; Silva, João Paulo; Singh, Navinder; Solberg, Erling J; Spiegel, Orr; Strand, Olav; Sundaresan, Siva; Ullmann, Wiebke; Voigt, Ulrich; Wall, Jake; Wattles, David; Wikelski, Martin; Wilmers, Christopher C; Wilson, John W; Wittemyer, George; Zięba, Filip; Zwijacz-Kozica, Tomasz; Mueller, Thomas

2018-01-26

Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission. Copyright © 2018, The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Eye Tracking Metrics for Workload Estimation in Flight Deck Operation

NASA Technical Reports Server (NTRS)

Ellis, Kyle; Schnell, Thomas

2010-01-01

Flight decks of the future are being enhanced through improved avionics that adapt to both aircraft and operator state. Eye tracking allows for non-invasive analysis of pilot eye movements, from which a set of metrics can be derived to effectively and reliably characterize workload. This research identifies eye tracking metrics that correlate to aircraft automation conditions, and identifies the correlation of pilot workload to the same automation conditions. Saccade length was used as an indirect index of pilot workload: Pilots in the fully automated condition were observed to have on average, larger saccadic movements in contrast to the guidance and manual flight conditions. The data set itself also provides a general model of human eye movement behavior and so ostensibly visual attention distribution in the cockpit for approach to land tasks with various levels of automation, by means of the same metrics used for workload algorithm development.

A low cost real-time motion tracking approach using webcam technology.

PubMed

Krishnan, Chandramouli; Washabaugh, Edward P; Seetharaman, Yogesh

2015-02-05

Physical therapy is an important component of gait recovery for individuals with locomotor dysfunction. There is a growing body of evidence that suggests that incorporating a motor learning task through visual feedback of movement trajectory is a useful approach to facilitate therapeutic outcomes. Visual feedback is typically provided by recording the subject's limb movement patterns using a three-dimensional motion capture system and displaying it in real-time using customized software. However, this approach can seldom be used in the clinic because of the technical expertise required to operate this device and the cost involved in procuring a three-dimensional motion capture system. In this paper, we describe a low cost two-dimensional real-time motion tracking approach using a simple webcam and an image processing algorithm in LabVIEW Vision Assistant. We also evaluated the accuracy of this approach using a high precision robotic device (Lokomat) across various walking speeds. Further, the reliability and feasibility of real-time motion-tracking were evaluated in healthy human participants. The results indicated that the measurements from the webcam tracking approach were reliable and accurate. Experiments on human subjects also showed that participants could utilize the real-time kinematic feedback generated from this device to successfully perform a motor learning task while walking on a treadmill. These findings suggest that the webcam motion tracking approach is a feasible low cost solution to perform real-time movement analysis and training. Copyright © 2014 Elsevier Ltd. All rights reserved.

A low cost real-time motion tracking approach using webcam technology

PubMed Central

Krishnan, Chandramouli; Washabaugh, Edward P.; Seetharaman, Yogesh

2014-01-01

Physical therapy is an important component of gait recovery for individuals with locomotor dysfunction. There is a growing body of evidence that suggests that incorporating a motor learning task through visual feedback of movement trajectory is a useful approach to facilitate therapeutic outcomes. Visual feedback is typically provided by recording the subject’s limb movement patterns using a three-dimensional motion capture system and displaying it in real-time using customized software. However, this approach can seldom be used in the clinic because of the technical expertise required to operate this device and the cost involved in procuring a three-dimensional motion capture system. In this paper, we describe a low cost two-dimensional real-time motion tracking approach using a simple webcam and an image processing algorithm in LabVIEW Vision Assistant. We also evaluated the accuracy of this approach using a high precision robotic device (Lokomat) across various walking speeds. Further, the reliability and feasibility of real-time motion-tracking were evaluated in healthy human participants. The results indicated that the measurements from the webcam tracking approach were reliable and accurate. Experiments on human subjects also showed that participants could utilize the real-time kinematic feedback generated from this device to successfully perform a motor learning task while walking on a treadmill. These findings suggest that the webcam motion tracking approach is a feasible low cost solution to perform real-time movement analysis and training. PMID:25555306

Impedance modulation and feedback corrections in tracking targets of variable size and frequency.

PubMed

Selen, Luc P J; van Dieën, Jaap H; Beek, Peter J

2006-11-01

Humans are able to adjust the accuracy of their movements to the demands posed by the task at hand. The variability in task execution caused by the inherent noisiness of the neuromuscular system can be tuned to task demands by both feedforward (e.g., impedance modulation) and feedback mechanisms. In this experiment, we studied both mechanisms, using mechanical perturbations to estimate stiffness and damping as indices of impedance modulation and submovement scaling as an index of feedback driven corrections. Eight subjects tracked three differently sized targets (0.0135, 0.0270, and 0.0405 rad) moving at three different frequencies (0.20, 0.25, and 0.33 Hz). Movement variability decreased with both decreasing target size and movement frequency, whereas stiffness and damping increased with decreasing target size, independent of movement frequency. These results are consistent with the theory that mechanical impedance acts as a filter of noisy neuromuscular signals but challenge stochastic theories of motor control that do not account for impedance modulation and only partially for feedback control. Submovements during unperturbed cycles were quantified in terms of their gain, i.e., the slope between their duration and amplitude in the speed profile. Submovement gain decreased with decreasing movement frequency and increasing target size. The results were interpreted to imply that submovement gain is related to observed tracking errors and that those tracking errors are expressed in units of target size. We conclude that impedance and submovement gain modulation contribute additively to tracking accuracy.

Movement Performance of Human-Robot Cooperation Control Based on EMG-Driven Hill-Type and Proportional Models for an Ankle Power-Assist Exoskeleton Robot.

PubMed

Ao, Di; Song, Rong; Gao, JinWu

2017-08-01

Although the merits of electromyography (EMG)-based control of powered assistive systems have been certified, the factors that affect the performance of EMG-based human-robot cooperation, which are very important, have received little attention. This study investigates whether a more physiologically appropriate model could improve the performance of human-robot cooperation control for an ankle power-assist exoskeleton robot. To achieve the goal, an EMG-driven Hill-type neuromusculoskeletal model (HNM) and a linear proportional model (LPM) were developed and calibrated through maximum isometric voluntary dorsiflexion (MIVD). The two control models could estimate the real-time ankle joint torque, and HNM is more accurate and can account for the change of the joint angle and muscle dynamics. Then, eight healthy volunteers were recruited to wear the ankle exoskeleton robot and complete a series of sinusoidal tracking tasks in the vertical plane. With the various levels of assist based on the two calibrated models, the subjects were instructed to track the target displayed on the screen as accurately as possible by performing ankle dorsiflexion and plantarflexion. Two measurements, the root mean square error (RMSE) and root mean square jerk (RMSJ), were derived from the assistant torque and kinematic signals to characterize the movement performances, whereas the amplitudes of the recorded EMG signals from the tibialis anterior (TA) and the gastrocnemius (GAS) were obtained to reflect the muscular efforts. The results demonstrated that the muscular effort and smoothness of tracking movements decreased with an increase in the assistant ratio. Compared with LPM, subjects made lower physical efforts and generated smoother movements when using HNM, which implied that a more physiologically appropriate model could enable more natural and human-like human-robot cooperation and has potential value for improvement of human-exoskeleton interaction in future applications.

A Bayesian Framework for Human Body Pose Tracking from Depth Image Sequences

PubMed Central

Zhu, Youding; Fujimura, Kikuo

2010-01-01

This paper addresses the problem of accurate and robust tracking of 3D human body pose from depth image sequences. Recovering the large number of degrees of freedom in human body movements from a depth image sequence is challenging due to the need to resolve the depth ambiguity caused by self-occlusions and the difficulty to recover from tracking failure. Human body poses could be estimated through model fitting using dense correspondences between depth data and an articulated human model (local optimization method). Although it usually achieves a high accuracy due to dense correspondences, it may fail to recover from tracking failure. Alternately, human pose may be reconstructed by detecting and tracking human body anatomical landmarks (key-points) based on low-level depth image analysis. While this method (key-point based method) is robust and recovers from tracking failure, its pose estimation accuracy depends solely on image-based localization accuracy of key-points. To address these limitations, we present a flexible Bayesian framework for integrating pose estimation results obtained by methods based on key-points and local optimization. Experimental results are shown and performance comparison is presented to demonstrate the effectiveness of the proposed approach. PMID:22399933

Direction of Perceived Motion and Eye Movements Show Similar Biases for Asymmetrically Windowed Moving Plaids

NASA Technical Reports Server (NTRS)

Beutter, B. R.; Mulligan, J. B.; Stone, L. S.; Hargens, Alan R. (Technical Monitor)

1995-01-01

We have shown that moving a plaid in an asymmetric window biases the perceived direction of motion (Beutter, Mulligan & Stone, ARVO 1994). We now explore whether these biased motion signals might also drive the smooth eye-movement response by comparing the perceived and tracked directions. The human smooth oculomotor response to moving plaids appears to be driven by the perceived rather than the veridical direction of motion. This suggests that human motion perception and smooth eye movements share underlying neural motion-processing substrates as has already been shown to be true for monkeys.

Home Range and Ranging Behaviour of Bornean Elephant (Elephas maximus borneensis) Females

PubMed Central

Alfred, Raymond; Ahmad, Abd Hamid; Payne, Junaidi; Williams, Christy; Ambu, Laurentius Nayan; How, Phua Mui; Goossens, Benoit

2012-01-01

Background Home range is defined as the extent and location of the area covered annually by a wild animal in its natural habitat. Studies of African and Indian elephants in landscapes of largely open habitats have indicated that the sizes of the home range are determined not only by the food supplies and seasonal changes, but also by numerous other factors including availability of water sources, habitat loss and the existence of man-made barriers. The home range size for the Bornean elephant had never been investigated before. Methodology/Principal Findings The first satellite tracking program to investigate the movement of wild Bornean elephants in Sabah was initiated in 2005. Five adult female elephants were immobilized and neck collars were fitted with tracking devices. The sizes of their home range and movement patterns were determined using location data gathered from a satellite tracking system and analyzed by using the Minimum Convex Polygon and Harmonic Mean methods. Home range size was estimated to be 250 to 400 km2 in a non-fragmented forest and 600 km2 in a fragmented forest. The ranging behavior was influenced by the size of the natural forest habitat and the availability of permanent water sources. The movement pattern was influenced by human disturbance and the need to move from one feeding site to another. Conclusions/Significance Home range and movement rate were influenced by the degree of habitat fragmentation. Once habitat was cleared or converted, the availability of food plants and water sources were reduced, forcing the elephants to travel to adjacent forest areas. Therefore movement rate in fragmented forest was higher than in the non-fragmented forest. Finally, in fragmented habitat human and elephant conflict occurrences were likely to be higher, due to increased movement bringing elephants into contact more often with humans. PMID:22347469

The environmental-data automated track annotation (Env-DATA) system: linking animal tracks with environmental data

USGS Publications Warehouse

Dodge, Somayeh; Bohrer, Gil; Weinzierl, Rolf P.; Davidson, Sarah C.; Kays, Roland; Douglas, David C.; Cruz, Sebastian; Han, J.; Brandes, David; Wikelski, Martin

2013-01-01

The movement of animals is strongly influenced by external factors in their surrounding environment such as weather, habitat types, and human land use. With advances in positioning and sensor technologies, it is now possible to capture animal locations at high spatial and temporal granularities. Likewise, scientists have an increasing access to large volumes of environmental data. Environmental data are heterogeneous in source and format, and are usually obtained at different spatiotemporal scales than movement data. Indeed, there remain scientific and technical challenges in developing linkages between the growing collections of animal movement data and the large repositories of heterogeneous remote sensing observations, as well as in the developments of new statistical and computational methods for the analysis of movement in its environmental context. These challenges include retrieval, indexing, efficient storage, data integration, and analytical techniques.

Microgravity

NASA Image and Video Library

2003-01-22

One concern about human adaptation to space is how returning from the microgravity of orbit to Earth can affect an astronaut's ability to fly safely. There are monitors and infrared video cameras to measure eye movements without having to affect the crew member. A computer screen provides moving images which the eye tracks while the brain determines what it is seeing. A video camera records movement of the subject's eyes. Researchers can then correlate perception and response. Test subjects perceive different images when a moving object is covered by a mask that is visible or invisible (above). Early results challenge the accepted theory that smooth pursuit -- the fluid eye movement that humans and primates have -- does not involve the higher brain. NASA results show that: Eye movement can predict human perceptual performance, smooth pursuit and saccadic (quick or ballistic) movement share some signal pathways, and common factors can make both smooth pursuit and visual perception produce errors in motor responses.

Understanding Visible Perception

NASA Technical Reports Server (NTRS)

2003-01-01

One concern about human adaptation to space is how returning from the microgravity of orbit to Earth can affect an astronaut's ability to fly safely. There are monitors and infrared video cameras to measure eye movements without having to affect the crew member. A computer screen provides moving images which the eye tracks while the brain determines what it is seeing. A video camera records movement of the subject's eyes. Researchers can then correlate perception and response. Test subjects perceive different images when a moving object is covered by a mask that is visible or invisible (above). Early results challenge the accepted theory that smooth pursuit -- the fluid eye movement that humans and primates have -- does not involve the higher brain. NASA results show that: Eye movement can predict human perceptual performance, smooth pursuit and saccadic (quick or ballistic) movement share some signal pathways, and common factors can make both smooth pursuit and visual perception produce errors in motor responses.

Human myosin VIIa is a very slow processive motor protein on various cellular actin structures.

PubMed

Sato, Osamu; Komatsu, Satoshi; Sakai, Tsuyoshi; Tsukasaki, Yoshikazu; Tanaka, Ryosuke; Mizutani, Takeomi; Watanabe, Tomonobu M; Ikebe, Reiko; Ikebe, Mitsuo

2017-06-30

Human myosin VIIa (MYO7A) is an actin-linked motor protein associated with human Usher syndrome (USH) type 1B, which causes human congenital hearing and visual loss. Although it has been thought that the role of human myosin VIIa is critical for USH1 protein tethering with actin and transportation along actin bundles in inner-ear hair cells, myosin VIIa's motor function remains unclear. Here, we studied the motor function of the tail-truncated human myosin VIIa dimer (HM7AΔTail/LZ) at the single-molecule level. We found that the HM7AΔTail/LZ moves processively on single actin filaments with a step size of 35 nm. Dwell-time distribution analysis indicated an average waiting time of 3.4 s, yielding ∼0.3 s -1 for the mechanical turnover rate; hence, the velocity of HM7AΔTail/LZ was extremely slow, at 11 nm·s -1 We also examined HM7AΔTail/LZ movement on various actin structures in demembranated cells. HM7AΔTail/LZ showed unidirectional movement on actin structures at cell edges, such as lamellipodia and filopodia. However, HM7AΔTail/LZ frequently missed steps on actin tracks and exhibited bidirectional movement at stress fibers, which was not observed with tail-truncated myosin Va. These results suggest that the movement of the human myosin VIIa motor protein is more efficient on lamellipodial and filopodial actin tracks than on stress fibers, which are composed of actin filaments with different polarity, and that the actin structures influence the characteristics of cargo transportation by human myosin VIIa. In conclusion, myosin VIIa movement appears to be suitable for translocating USH1 proteins on stereocilia actin bundles in inner-ear hair cells. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Comprehensive Oculomotor Behavioral Response Assessment (COBRA)

NASA Technical Reports Server (NTRS)

Stone, Leland S. (Inventor); Liston, Dorion B. (Inventor)

2017-01-01

An eye movement-based methodology and assessment tool may be used to quantify many aspects of human dynamic visual processing using a relatively simple and short oculomotor task, noninvasive video-based eye tracking, and validated oculometric analysis techniques. By examining the eye movement responses to a task including a radially-organized appropriately randomized sequence of Rashbass-like step-ramp pursuit-tracking trials, distinct performance measurements may be generated that may be associated with, for example, pursuit initiation (e.g., latency and open-loop pursuit acceleration), steady-state tracking (e.g., gain, catch-up saccade amplitude, and the proportion of the steady-state response consisting of smooth movement), direction tuning (e.g., oblique effect amplitude, horizontal-vertical asymmetry, and direction noise), and speed tuning (e.g., speed responsiveness and noise). This quantitative approach may provide fast and results (e.g., a multi-dimensional set of oculometrics and a single scalar impairment index) that can be interpreted by one without a high degree of scientific sophistication or extensive training.

Design and implementation of a MRI compatible and dynamic phantom simulating the motion of a tumor in the liver under the breathing cycle

NASA Astrophysics Data System (ADS)

Geelhand de Merxem, Arnould; Lechien, Vianney; Thibault, Tanguy; Dasnoy, Damien; Macq, Benoît

2017-11-01

In the context of cancer treatment by proton therapy, research is carried out on the use magnetic resonance imaging (MRI) to perform real-time tracking of tumors during irradiation. The purpose of this combination is to reduce the irradiation of healthy tissues surrounding the tumor, while using a non-ionizing imaging method. Therefore, it is necessary to validate the tracking algorithms on real-time MRI sequences by using physical simulators, i.e. a phantom. Our phantom is a device representing a liver with hepatocellular carcinoma, a stomach and a pancreas close to the anatomy and the magnetic properties of the human body, animated by a motion similar to the one induced by the respiration. Many anatomical or mobile phantoms already exist, but the purpose here is to combine a reliable representation of the abdominal organs with the creation and the evaluation of a programmable movement in the same device, which makes it unique. The phantom is composed of surrogate organs made of CAGN gels. These organs are placed in a transparent box filled with water and attached to an elastic membrane. A programmable electro-pneumatic system creates a movement, similarly to a human diaphragm, by inflating and deflating the membrane. The average relaxation times of the synthetic organs belongs to a range corresponding to the human organs values (T1 = [458.7-1660] ms, T2 = [39.3-89.1] ms). The displacement of the tumor is tracked in real time by a camera inside the MRI. The amplitude of the movement varies from 12.8 to 20.1 mm for a periodic and repeatable movement. Irregular breath patterns can be created with a maximum amplitude of 40 mm.

Visual Data Mining: An Exploratory Approach to Analyzing Temporal Patterns of Eye Movements

ERIC Educational Resources Information Center

Yu, Chen; Yurovsky, Daniel; Xu, Tian

2012-01-01

Infant eye movements are an important behavioral resource to understand early human development and learning. But the complexity and amount of gaze data recorded from state-of-the-art eye-tracking systems also pose a challenge: how does one make sense of such dense data? Toward this goal, this article describes an interactive approach based on…

Contrast and assimilation in motion perception and smooth pursuit eye movements.

PubMed

Spering, Miriam; Gegenfurtner, Karl R

2007-09-01

The analysis of visual motion serves many different functions ranging from object motion perception to the control of self-motion. The perception of visual motion and the oculomotor tracking of a moving object are known to be closely related and are assumed to be controlled by shared brain areas. We compared perceived velocity and the velocity of smooth pursuit eye movements in human observers in a paradigm that required the segmentation of target object motion from context motion. In each trial, a pursuit target and a visual context were independently perturbed simultaneously to briefly increase or decrease in speed. Observers had to accurately track the target and estimate target speed during the perturbation interval. Here we show that the same motion signals are processed in fundamentally different ways for perception and steady-state smooth pursuit eye movements. For the computation of perceived velocity, motion of the context was subtracted from target motion (motion contrast), whereas pursuit velocity was determined by the motion average (motion assimilation). We conclude that the human motion system uses these computations to optimally accomplish different functions: image segmentation for object motion perception and velocity estimation for the control of smooth pursuit eye movements.

Motion analysis report

NASA Technical Reports Server (NTRS)

Badler, N. I.

1985-01-01

Human motion analysis is the task of converting actual human movements into computer readable data. Such movement information may be obtained though active or passive sensing methods. Active methods include physical measuring devices such as goniometers on joints of the body, force plates, and manually operated sensors such as a Cybex dynamometer. Passive sensing de-couples the position measuring device from actual human contact. Passive sensors include Selspot scanning systems (since there is no mechanical connection between the subject's attached LEDs and the infrared sensing cameras), sonic (spark-based) three-dimensional digitizers, Polhemus six-dimensional tracking systems, and image processing systems based on multiple views and photogrammetric calculations.

Understanding Human Mobility from Twitter

PubMed Central

Jurdak, Raja; Zhao, Kun; Liu, Jiajun; AbouJaoude, Maurice; Cameron, Mark; Newth, David

2015-01-01

Understanding human mobility is crucial for a broad range of applications from disease prediction to communication networks. Most efforts on studying human mobility have so far used private and low resolution data, such as call data records. Here, we propose Twitter as a proxy for human mobility, as it relies on publicly available data and provides high resolution positioning when users opt to geotag their tweets with their current location. We analyse a Twitter dataset with more than six million geotagged tweets posted in Australia, and we demonstrate that Twitter can be a reliable source for studying human mobility patterns. Our analysis shows that geotagged tweets can capture rich features of human mobility, such as the diversity of movement orbits among individuals and of movements within and between cities. We also find that short- and long-distance movers both spend most of their time in large metropolitan areas, in contrast with intermediate-distance movers’ movements, reflecting the impact of different modes of travel. Our study provides solid evidence that Twitter can indeed be a useful proxy for tracking and predicting human movement. PMID:26154597

Using Posture Estimation to Enhance Personal Inertial Tracking

DTIC Science & Technology

2016-06-01

used to create and simulate a human avatar that mimics movement in a virtual environment. As of 2004, only the right arm had been modeled. The MARG...dissertation, Dept. of Philosophy, The University of Tennessee, Knoxville, TN, 2013. [8] F. Yildiz, “Implementation of a human avatar for the MARG

Use of a genetic algorithm for the analysis of eye movements from the linear vestibulo-ocular reflex

NASA Technical Reports Server (NTRS)

Shelhamer, M.

2001-01-01

It is common in vestibular and oculomotor testing to use a single-frequency (sine) or combination of frequencies [sum-of-sines (SOS)] stimulus for head or target motion. The resulting eye movements typically contain a smooth tracking component, which follows the stimulus, in which are interspersed rapid eye movements (saccades or fast phases). The parameters of the smooth tracking--the amplitude and phase of each component frequency--are of interest; many methods have been devised that attempt to identify and remove the fast eye movements from the smooth. We describe a new approach to this problem, tailored to both single-frequency and sum-of-sines stimulation of the human linear vestibulo-ocular reflex. An approximate derivative is used to identify fast movements, which are then omitted from further analysis. The remaining points form a series of smooth tracking segments. A genetic algorithm is used to fit these segments together to form a smooth (but disconnected) wave form, by iteratively removing biases due to the missing fast phases. A genetic algorithm is an iterative optimization procedure; it provides a basis for extending this approach to more complex stimulus-response situations. In the SOS case, the genetic algorithm estimates the amplitude and phase values of the component frequencies as well as removing biases.

Generating optimal control simulations of musculoskeletal movement using OpenSim and MATLAB.

PubMed

Lee, Leng-Feng; Umberger, Brian R

2016-01-01

Computer modeling, simulation and optimization are powerful tools that have seen increased use in biomechanics research. Dynamic optimizations can be categorized as either data-tracking or predictive problems. The data-tracking approach has been used extensively to address human movement problems of clinical relevance. The predictive approach also holds great promise, but has seen limited use in clinical applications. Enhanced software tools would facilitate the application of predictive musculoskeletal simulations to clinically-relevant research. The open-source software OpenSim provides tools for generating tracking simulations but not predictive simulations. However, OpenSim includes an extensive application programming interface that permits extending its capabilities with scripting languages such as MATLAB. In the work presented here, we combine the computational tools provided by MATLAB with the musculoskeletal modeling capabilities of OpenSim to create a framework for generating predictive simulations of musculoskeletal movement based on direct collocation optimal control techniques. In many cases, the direct collocation approach can be used to solve optimal control problems considerably faster than traditional shooting methods. Cyclical and discrete movement problems were solved using a simple 1 degree of freedom musculoskeletal model and a model of the human lower limb, respectively. The problems could be solved in reasonable amounts of time (several seconds to 1-2 hours) using the open-source IPOPT solver. The problems could also be solved using the fmincon solver that is included with MATLAB, but the computation times were excessively long for all but the smallest of problems. The performance advantage for IPOPT was derived primarily by exploiting sparsity in the constraints Jacobian. The framework presented here provides a powerful and flexible approach for generating optimal control simulations of musculoskeletal movement using OpenSim and MATLAB. This should allow researchers to more readily use predictive simulation as a tool to address clinical conditions that limit human mobility.

Generating optimal control simulations of musculoskeletal movement using OpenSim and MATLAB

PubMed Central

Lee, Leng-Feng

2016-01-01

Computer modeling, simulation and optimization are powerful tools that have seen increased use in biomechanics research. Dynamic optimizations can be categorized as either data-tracking or predictive problems. The data-tracking approach has been used extensively to address human movement problems of clinical relevance. The predictive approach also holds great promise, but has seen limited use in clinical applications. Enhanced software tools would facilitate the application of predictive musculoskeletal simulations to clinically-relevant research. The open-source software OpenSim provides tools for generating tracking simulations but not predictive simulations. However, OpenSim includes an extensive application programming interface that permits extending its capabilities with scripting languages such as MATLAB. In the work presented here, we combine the computational tools provided by MATLAB with the musculoskeletal modeling capabilities of OpenSim to create a framework for generating predictive simulations of musculoskeletal movement based on direct collocation optimal control techniques. In many cases, the direct collocation approach can be used to solve optimal control problems considerably faster than traditional shooting methods. Cyclical and discrete movement problems were solved using a simple 1 degree of freedom musculoskeletal model and a model of the human lower limb, respectively. The problems could be solved in reasonable amounts of time (several seconds to 1–2 hours) using the open-source IPOPT solver. The problems could also be solved using the fmincon solver that is included with MATLAB, but the computation times were excessively long for all but the smallest of problems. The performance advantage for IPOPT was derived primarily by exploiting sparsity in the constraints Jacobian. The framework presented here provides a powerful and flexible approach for generating optimal control simulations of musculoskeletal movement using OpenSim and MATLAB. This should allow researchers to more readily use predictive simulation as a tool to address clinical conditions that limit human mobility. PMID:26835184

Infrared dim and small target detecting and tracking method inspired by Human Visual System

NASA Astrophysics Data System (ADS)

Dong, Xiabin; Huang, Xinsheng; Zheng, Yongbin; Shen, Lurong; Bai, Shengjian

2014-01-01

Detecting and tracking dim and small target in infrared images and videos is one of the most important techniques in many computer vision applications, such as video surveillance and infrared imaging precise guidance. Recently, more and more algorithms based on Human Visual System (HVS) have been proposed to detect and track the infrared dim and small target. In general, HVS concerns at least three mechanisms including contrast mechanism, visual attention and eye movement. However, most of the existing algorithms simulate only a single one of the HVS mechanisms, resulting in many drawbacks of these algorithms. A novel method which combines the three mechanisms of HVS is proposed in this paper. First, a group of Difference of Gaussians (DOG) filters which simulate the contrast mechanism are used to filter the input image. Second, a visual attention, which is simulated by a Gaussian window, is added at a point near the target in order to further enhance the dim small target. This point is named as the attention point. Eventually, the Proportional-Integral-Derivative (PID) algorithm is first introduced to predict the attention point of the next frame of an image which simulates the eye movement of human being. Experimental results of infrared images with different types of backgrounds demonstrate the high efficiency and accuracy of the proposed method to detect and track the dim and small targets.

[A tracking function of human eye in microgravity and during readaptation to earth's gravity].

PubMed

Kornilova, L N

2001-01-01

The paper summarizes results of electro-oculography of all ways of visual tracking: fixative eye movements (saccades), smooth pursuit of linearly, pendulum-like and circularly moving point stimuli, pursuit of vertically moving foveoretinal optokinetic stimuli, and presents values of thresholds and amplification coefficients of the optokinetic nystagmus during tracking of linear movement of foveoretinal optokinetic stimuli. Investigations were performed aboard the Salyut and Mir space stations with participation of 31 cosmonauts of whom 27 made long-term (76 up to 438 day) and 4 made short-term (7 to 9 day) missions. It was shown that in space flight the saccadic structure within the tracking reaction does not change; yet, corrective movements (additional microsaccades to achieve tracking) appeared in 47% of observations at the onset and in 76% of observations on months 3 to 6 of space flight. After landing, the structure of vertical saccades was found altered in half the cosmonauts. No matter in or after flight, reverse nystagmus was present along with the gaze nystagmus during static saccades in 22% (7 cosmonauts) of the observations. Amplitude of tracking vertically, diagonally or circularly moving stimuli was significantly reduced as period on mission increased. Early in flight (40% of the cosmonauts) and shortly afterwards (21% of the cosmonauts) the structure of smooth tracking reaction was totally broken up, that is eye followed stimulus with micro- or macrosaccades. The structure of smooth eye tracking recovered on flight days 6-8 and on postflight days 3-4. However, in 46% of the cosmonauts on long-term missions the structure of smooth eye tracking was noted to be disturbed periodically, i.e. smooth tracking was replaced by saccadic.

Experimental verification of a two-dimensional respiratory motion compensation system with ultrasound tracking technique in radiation therapy.

PubMed

Ting, Lai-Lei; Chuang, Ho-Chiao; Liao, Ai-Ho; Kuo, Chia-Chun; Yu, Hsiao-Wei; Zhou, Yi-Liang; Tien, Der-Chi; Jeng, Shiu-Chen; Chiou, Jeng-Fong

2018-05-01

This study proposed respiratory motion compensation system (RMCS) combined with an ultrasound image tracking algorithm (UITA) to compensate for respiration-induced tumor motion during radiotherapy, and to address the problem of inaccurate radiation dose delivery caused by respiratory movement. This study used an ultrasound imaging system to monitor respiratory movements combined with the proposed UITA and RMCS for tracking and compensation of the respiratory motion. Respiratory motion compensation was performed using prerecorded human respiratory motion signals and also sinusoidal signals. A linear accelerator was used to deliver radiation doses to GAFchromic EBT3 dosimetry film, and the conformity index (CI), root-mean-square error, compensation rate (CR), and planning target volume (PTV) were used to evaluate the tracking and compensation performance of the proposed system. Human respiratory pattern signals were captured using the UITA and compensated by the RMCS, which yielded CR values of 34-78%. In addition, the maximum coronal area of the PTV ranged from 85.53 mm 2 to 351.11 mm 2 (uncompensated), which reduced to from 17.72 mm 2 to 66.17 mm 2 after compensation, with an area reduction ratio of up to 90%. In real-time monitoring of the respiration compensation state, the CI values for 85% and 90% isodose areas increased to 0.7 and 0.68, respectively. The proposed UITA and RMCS can reduce the movement of the tracked target relative to the LINAC in radiation therapy, thereby reducing the required size of the PTV margin and increasing the effect of the radiation dose received by the treatment target. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Spatial Updating and the Maintenance of Visual Constancy

PubMed Central

Klier, Eliana M.; Angelaki, Dora E.

2008-01-01

Spatial updating is the means by which we keep track of the locations of objects in space even as we move. Four decades of research have shown that humans and non-human primates can take the amplitude and direction of intervening movements into account, including saccades (both head-fixed and head-free), pursuit, whole-body rotations and translations. At the neuronal level, spatial updating is thought to be maintained by receptive field locations that shift with changes in gaze and evidence for such shifts have been shown in several cortical areas. These regions receive information about the intervening movement from several sources including motor efference copies when a voluntary movement is made and vestibular/somatosensory signals when the body is in motion. Many of these updating signals arise from brainstem regions that monitor our ongoing movements and subsequently transmit this information to the cortex via pathways that likely include the thalamus. Several issues of debate include (1) the relative contribution of extra-retinal sensory and efference copy signals to spatial updating, (2) the source of an updating signal for real life, three-dimensional motion that cannot arise from brain areas encoding only two-dimensional commands, and (3) the reference frames used by the brain to integrate updating signals from various sources. This review highlights the relevant spatial updating studies and provides a summary of the field today. We find that spatial constancy is maintained by a highly evolved neural mechanism that keeps track of our movements, transmits this information to relevant brain regions, and then uses this information to change the way in which single neurons respond. In this way, we are able to keep track of relevant objects in the outside world and interact with them in meaningful ways. PMID:18786618

A general-purpose framework to simulate musculoskeletal system of human body: using a motion tracking approach.

PubMed

Ehsani, Hossein; Rostami, Mostafa; Gudarzi, Mohammad

2016-02-01

Computation of muscle force patterns that produce specified movements of muscle-actuated dynamic models is an important and challenging problem. This problem is an undetermined one, and then a proper optimization is required to calculate muscle forces. The purpose of this paper is to develop a general model for calculating all muscle activation and force patterns in an arbitrary human body movement. For this aim, the equations of a multibody system forward dynamics, which is considered for skeletal system of the human body model, is derived using Lagrange-Euler formulation. Next, muscle contraction dynamics is added to this model and forward dynamics of an arbitrary musculoskeletal system is obtained. For optimization purpose, the obtained model is used in computed muscle control algorithm, and a closed-loop system for tracking desired motions is derived. Finally, a popular sport exercise, biceps curl, is simulated by using this algorithm and the validity of the obtained results is evaluated via EMG signals.

Can smartwatches replace smartphones for posture tracking?

PubMed

Mortazavi, Bobak; Nemati, Ebrahim; VanderWall, Kristina; Flores-Rodriguez, Hector G; Cai, Jun Yu Jacinta; Lucier, Jessica; Naeim, Arash; Sarrafzadeh, Majid

2015-10-22

This paper introduces a human posture tracking platform to identify the human postures of sitting, standing or lying down, based on a smartwatch. This work develops such a system as a proof-of-concept study to investigate a smartwatch's ability to be used in future remote health monitoring systems and applications. This work validates the smartwatches' ability to track the posture of users accurately in a laboratory setting while reducing the sampling rate to potentially improve battery life, the first steps in verifying that such a system would work in future clinical settings. The algorithm developed classifies the transitions between three posture states of sitting, standing and lying down, by identifying these transition movements, as well as other movements that might be mistaken for these transitions. The system is trained and developed on a Samsung Galaxy Gear smartwatch, and the algorithm was validated through a leave-one-subject-out cross-validation of 20 subjects. The system can identify the appropriate transitions at only 10 Hz with an F-score of 0.930, indicating its ability to effectively replace smart phones, if needed.

Tracking the movements of a post-nesting Southern River Terrapin (Batagur affinis edwardmolli)

NASA Astrophysics Data System (ADS)

Chen, Pelf-Nyok; Wong, Adrian

2015-09-01

A Southern River Terrapin (Batagur affinis edwardmolli) Conservation Project was initiated on one terrapin nesting bank in 2011, following the discovery of a River Terrapin population in the Kemaman River, Terengganu in 2010. Since this project was initiated, Turtle Conservation Society of Malaysia (TCS) was instrumental in the gazettement of three nesting banks along the Kemaman River, from which all River Terrapin eggs are collected for incubation. However, there are at least a dozen other "unprotected" nesting banks along the river, where all eggs were collected for human consumption. This project attempted to determine the movements of a post-nesting River Terrapin, with hopes that it would provide the preliminary baseline information on the utilization of adjacent nesting banks. The solution was a GPS tracking device that transmitted coordinates every hour over cellular networks. Location-based data was sent via Short Message Service (SMS) to our own SMS gateway running on a Raspberry Pi credit-card size computer, which was then logged in a database and presented graphically via Google Maps. It was a complete tracking and monitoring system. This solution enabled researchers to remotely track the movements of a River Terrapin, hence reducing the costs of research. The movements of a post-nesting River Terrapin were tracked for eight days before the battery was drained. On the third day, this River Terrapin ascended an adjacent riverbank and spent less than an hour on the bank, presumably to deposit her remaining eggs. This study confirmed that River Terrapins do utilize other suitable nesting banks if/whenever available. Results from such tracking studies will be used to leverage on the protection of adjacent nesting banks, thus providing greater protection for the critically endangered River Terrapins.

Does the brain use sliding variables for the control of movements?

PubMed

Hanneton, S; Berthoz, A; Droulez, J; Slotine, J J

1997-12-01

Delays in the transmission of sensory and motor information prevent errors from being instantaneously available to the central nervous system (CNS) and can reduce the stability of a closed-loop control strategy. On the other hand, the use of a pure feedforward control (inverse dynamics) requires a perfect knowledge of the dynamic behavior of the body and of manipulated objects. Sensory feedback is essential both to accommodate unexpected errors and events and to compensate for uncertainties about the dynamics of the body. Experimental observations concerning the control of posture, gaze and limbs have shown that the CNS certainly uses a combination of closed-loop and open-loop control. Feedforward components of movement, such as eye saccades, occur intermittently and present a stereotyped kinematic profile. In visuo-manual tracking tasks, hand movements exhibit velocity peaks that occur intermittently. When a delay or a slow dynamics are inserted in the visuo-manual control loop, intermittent step-and-hold movements appear clearly in the hand trajectory. In this study, we investigated strategies used by human subjects involved in the control of a particular dynamic system. We found strong evidence for substantial nonlinearities in the commands produced. The presence of step-and-hold movements seemed to be the major source of nonlinearities in the control loop. Furthermore, the stereotyped ballistic-like kinematics of these rapid and corrective movements suggests that they were produced in an open-loop way by the CNS. We analyzed the generation of ballistic movements in the light of sliding control theory assuming that they occurred when a sliding variable exceeded a constant threshold. In this framework, a sliding variable is defined as a composite variable (a combination of the instantaneous tracking error and its temporal derivatives) that fulfills a specific stability criterion. Based on this hypothesis and on the assumption of a constant reaction time, the tracking error and its derivatives should be correlated at a particular time lag before movement onset. A peak of correlation was found for a physiologically plausible reaction time, corresponding to a stable composite variable. The direction and amplitude of the ongoing stereotyped movements seemed also be adjusted in order to minimize this variable. These findings suggest that, during visually guided movements, human subjects attempt to minimize such a composite variable and not the instantaneous error. This minimization seems to be obtained by the execution of stereotyped corrective movements.

Representational Momentum for the Human Body: Awkwardness Matters, Experience Does Not

ERIC Educational Resources Information Center

Wilson, Margaret; Lancaster, Jessy; Emmorey, Karen

2010-01-01

Perception of the human body appears to involve predictive simulations that project forward to track unfolding body-motion events. Here we use representational momentum (RM) to investigate whether implicit knowledge of a learned arbitrary system of body movement such as sign language influences this prediction process, and how this compares to…

Achieving climate connectivity in a fragmented landscape

PubMed Central

Lawler, Joshua J.; McRae, Brad H.; Nuñez, Tristan A.; Theobald, David M.

2016-01-01

The contiguous United States contains a disconnected patchwork of natural lands. This fragmentation by human activities limits species’ ability to track suitable climates as they rapidly shift. However, most models that project species movement needs have not examined where fragmentation will limit those movements. Here, we quantify climate connectivity, the capacity of landscape configuration to allow species movement in the face of dynamically shifting climate. Using this metric, we assess to what extent habitat fragmentation will limit species movements in response to climate change. We then evaluate how creating corridors to promote climate connectivity could potentially mitigate these restrictions, and we assess where strategies to increase connectivity will be most beneficial. By analyzing fragmentation patterns across the contiguous United States, we demonstrate that only 41% of natural land area retains enough connectivity to allow plants and animals to maintain climatic parity as the climate warms. In the eastern United States, less than 2% of natural area is sufficiently connected. Introducing corridors to facilitate movement through human-dominated regions increases the percentage of climatically connected natural area to 65%, with the most impactful gains in low-elevation regions, particularly in the southeastern United States. These climate connectivity analyses allow ecologists and conservation practitioners to determine the most effective regions for increasing connectivity. More importantly, our findings demonstrate that increasing climate connectivity is critical for allowing species to track rapidly changing climates, reconfiguring habitats to promote access to suitable climates. PMID:27298349

Achieving climate connectivity in a fragmented landscape.

PubMed

McGuire, Jenny L; Lawler, Joshua J; McRae, Brad H; Nuñez, Tristan A; Theobald, David M

2016-06-28

The contiguous United States contains a disconnected patchwork of natural lands. This fragmentation by human activities limits species' ability to track suitable climates as they rapidly shift. However, most models that project species movement needs have not examined where fragmentation will limit those movements. Here, we quantify climate connectivity, the capacity of landscape configuration to allow species movement in the face of dynamically shifting climate. Using this metric, we assess to what extent habitat fragmentation will limit species movements in response to climate change. We then evaluate how creating corridors to promote climate connectivity could potentially mitigate these restrictions, and we assess where strategies to increase connectivity will be most beneficial. By analyzing fragmentation patterns across the contiguous United States, we demonstrate that only 41% of natural land area retains enough connectivity to allow plants and animals to maintain climatic parity as the climate warms. In the eastern United States, less than 2% of natural area is sufficiently connected. Introducing corridors to facilitate movement through human-dominated regions increases the percentage of climatically connected natural area to 65%, with the most impactful gains in low-elevation regions, particularly in the southeastern United States. These climate connectivity analyses allow ecologists and conservation practitioners to determine the most effective regions for increasing connectivity. More importantly, our findings demonstrate that increasing climate connectivity is critical for allowing species to track rapidly changing climates, reconfiguring habitats to promote access to suitable climates.

Variability of human corticospinal excitability tracks the state of action preparation.

PubMed

Klein-Flügge, Miriam C; Nobbs, David; Pitcher, Julia B; Bestmann, Sven

2013-03-27

Task-evoked trial-by-trial variability is a ubiquitous property of neural responses, yet its functional role remains largely unclear. Recent work in nonhuman primates shows that the temporal structure of neural variability in several brain regions is task-related. For example, trial-by-trial variability in premotor cortex tracks motor preparation with increasingly consistent firing rates and thus a decline in variability before movement onset. However, whether noninvasive measures of the variability of population activity available from humans can similarly track the preparation of actions remains unknown. We tested this by using single-pulse transcranial magnetic stimulation (TMS) over primary motor cortex (M1) to measure corticospinal excitability (CSE) at different times during action preparation. First, we established the basic properties of intrinsic CSE variability at rest. Then, during the task, responses (left or right button presses) were either directly instructed (forced choice) or resulted from a value decision (choice). Before movement onset, we observed a temporally specific task-related decline in CSE variability contralateral to the responding hand. This decline was stronger in fast-response compared with slow-response trials, consistent with data in nonhuman primates. For the nonresponding hand, CSE variability also decreased, but only in choice trials, and earlier compared with the responding hand, possibly reflecting choice-specific suppression of unselected actions. These findings suggest that human CSE variability measured by TMS over M1 tracks the state of motor preparation, and may reflect the optimization of preparatory population activity. This provides novel avenues in humans to assess the dynamics of action preparation but also more complex processes, such as choice-to-action transformations.

CAT & MAUS: A novel system for true dynamic motion measurement of underlying bony structures with compensation for soft tissue movement.

PubMed

Jia, Rui; Monk, Paul; Murray, David; Noble, J Alison; Mellon, Stephen

2017-09-06

Optoelectronic motion capture systems are widely employed to measure the movement of human joints. However, there can be a significant discrepancy between the data obtained by a motion capture system (MCS) and the actual movement of underlying bony structures, which is attributed to soft tissue artefact. In this paper, a computer-aided tracking and motion analysis with ultrasound (CAT & MAUS) system with an augmented globally optimal registration algorithm is presented to dynamically track the underlying bony structure during movement. The augmented registration part of CAT & MAUS was validated with a high system accuracy of 80%. The Euclidean distance between the marker-based bony landmark and the bony landmark tracked by CAT & MAUS was calculated to quantify the measurement error of an MCS caused by soft tissue artefact during movement. The average Euclidean distance between the target bony landmark measured by each of the CAT & MAUS system and the MCS alone varied from 8.32mm to 16.87mm in gait. This indicates the discrepancy between the MCS measured bony landmark and the actual underlying bony landmark. Moreover, Procrustes analysis was applied to demonstrate that CAT & MAUS reduces the deformation of the body segment shape modeled by markers during motion. The augmented CAT & MAUS system shows its potential to dynamically detect and locate actual underlying bony landmarks, which reduces the MCS measurement error caused by soft tissue artefact during movement. Copyright © 2017 Elsevier Ltd. All rights reserved.

State-Based Delay Representation and Its Transfer from a Game of Pong to Reaching and Tracking

PubMed Central

Leib, Raz; Pressman, Assaf; Simo, Lucia S.; Karniel, Amir

2017-01-01

Abstract To accurately estimate the state of the body, the nervous system needs to account for delays between signals from different sensory modalities. To investigate how such delays may be represented in the sensorimotor system, we asked human participants to play a virtual pong game in which the movement of the virtual paddle was delayed with respect to their hand movement. We tested the representation of this new mapping between the hand and the delayed paddle by examining transfer of adaptation to blind reaching and blind tracking tasks. These blind tasks enabled to capture the representation in feedforward mechanisms of movement control. A Time Representation of the delay is an estimation of the actual time lag between hand and paddle movements. A State Representation is a representation of delay using current state variables: the distance between the paddle and the ball originating from the delay may be considered as a spatial shift; the low sensitivity in the response of the paddle may be interpreted as a minifying gain; and the lag may be attributed to a mechanical resistance that influences paddle’s movement. We found that the effects of prolonged exposure to the delayed feedback transferred to blind reaching and tracking tasks and caused participants to exhibit hypermetric movements. These results, together with simulations of our representation models, suggest that delay is not represented based on time, but rather as a spatial gain change in visuomotor mapping. PMID:29379875

Which way and how far? Tracking of translation and rotation information for human path integration.

PubMed

Chrastil, Elizabeth R; Sherrill, Katherine R; Hasselmo, Michael E; Stern, Chantal E

2016-10-01

Path integration, the constant updating of the navigator's knowledge of position and orientation during movement, requires both visuospatial knowledge and memory. This study aimed to develop a systems-level understanding of human path integration by examining the basic building blocks of path integration in humans. To achieve this goal, we used functional imaging to examine the neural mechanisms that support the tracking and memory of translational and rotational components of human path integration. Critically, and in contrast to previous studies, we examined movement in translation and rotation tasks with no defined end-point or goal. Navigators accumulated translational and rotational information during virtual self-motion. Activity in hippocampus, retrosplenial cortex (RSC), and parahippocampal cortex (PHC) increased during both translation and rotation encoding, suggesting that these regions track self-motion information during path integration. These results address current questions regarding distance coding in the human brain. By implementing a modified delayed match to sample paradigm, we also examined the encoding and maintenance of path integration signals in working memory. Hippocampus, PHC, and RSC were recruited during successful encoding and maintenance of path integration information, with RSC selective for tasks that required processing heading rotation changes. These data indicate distinct working memory mechanisms for translation and rotation, which are essential for updating neural representations of current location. The results provide evidence that hippocampus, PHC, and RSC flexibly track task-relevant translation and rotation signals for path integration and could form the hub of a more distributed network supporting spatial navigation. Hum Brain Mapp 37:3636-3655, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Eye Movements During Everyday Behavior Predict Personality Traits.

PubMed

Hoppe, Sabrina; Loetscher, Tobias; Morey, Stephanie A; Bulling, Andreas

2018-01-01

Besides allowing us to perceive our surroundings, eye movements are also a window into our mind and a rich source of information on who we are, how we feel, and what we do. Here we show that eye movements during an everyday task predict aspects of our personality. We tracked eye movements of 42 participants while they ran an errand on a university campus and subsequently assessed their personality traits using well-established questionnaires. Using a state-of-the-art machine learning method and a rich set of features encoding different eye movement characteristics, we were able to reliably predict four of the Big Five personality traits (neuroticism, extraversion, agreeableness, conscientiousness) as well as perceptual curiosity only from eye movements. Further analysis revealed new relations between previously neglected eye movement characteristics and personality. Our findings demonstrate a considerable influence of personality on everyday eye movement control, thereby complementing earlier studies in laboratory settings. Improving automatic recognition and interpretation of human social signals is an important endeavor, enabling innovative design of human-computer systems capable of sensing spontaneous natural user behavior to facilitate efficient interaction and personalization.

Evaluation of an eye-pointer interaction device for human-computer interaction.

PubMed

Cáceres, Enrique; Carrasco, Miguel; Ríos, Sebastián

2018-03-01

Advances in eye-tracking technology have led to better human-computer interaction, and involve controlling a computer without any kind of physical contact. This research describes the transformation of a commercial eye-tracker for use as an alternative peripheral device in human-computer interactions, implementing a pointer that only needs the eye movements of a user facing a computer screen, thus replacing the need to control the software by hand movements. The experiment was performed with 30 test individuals who used the prototype with a set of educational videogames. The results show that, although most of the test subjects would prefer a mouse to control the pointer, the prototype tested has an empirical precision similar to that of the mouse, either when trying to control its movements or when attempting to click on a point of the screen.

Configural processing of biological motion in human superior temporal sulcus.

PubMed

Thompson, James C; Clarke, Michele; Stewart, Tennille; Puce, Aina

2005-09-28

Observers recognize subtle changes in the movements of others with relative ease. However, tracking a walking human is computationally difficult, because the degree of articulation is high and scene changes can temporarily occlude parts of the moving figure. Here, we used functional magnetic resonance imaging to test the hypothesis that the superior temporal sulcus (STS) uses form cues to aid biological movement tracking. The same 10 healthy subjects detected human gait changes in a walking mannequin in two experiments. In experiment 1, we tested the effects of configural change and occlusion. The walking mannequin was presented intact or with the limbs and torso apart in visual space and either unoccluded or occluded by a set of vertical white bars. In experiment 2, the effects of inversion and occlusion were investigated, using an intact walking mannequin. Subjects reliably detected gait changes under all stimulus conditions. The intact walker produced significantly greater activation in the STS, inferior temporal sulcus (ITS), and inferior parietal cortex relative to the apart walker, regardless of occlusion. Interestingly, STS and ITS activation to the upright versus inverted walker was not significantly different. In contrast, superior parietal lobule and parieto-occipital cortex showed greater activation to the apart relative to intact walker. In the absence of an intact body configuration, parietal cortex activity increased to the independent movements of the limbs and torso. Our data suggest that the STS may use a body configuration-based model to process biological movement, thus forming a representation that survives partial occlusion.

Recovery and positive psychology: parallel themes and potential synergies.

PubMed

Resnick, Sandra G; Rosenheck, Robert A

2006-01-01

The positive psychology movement studies the sources of human strength and the foundations of the "good life." Like the recovery movement, it focuses on personal fulfillment and well-being more than on mental illness. These movements have followed separate but parallel tracks. Positive psychology has traveled an academic and empirical path and the recovery movement has followed a grassroots advocacy model. The authors describe the successful use of the Values in Action Inventory of Strengths in a Department of Veterans Affairs psychiatric rehabilitation program. They argue for the integration of positive psychology and the recovery movement: positive psychology provides a potentially useful framework for further defining and fostering the goals of recovery, and the recovery movement can expand the hitherto limited application of positive psychology.

Associated reactions during a visual pursuit position tracking task in hemiplegic and quadriplegic cerebral palsy.

PubMed

Chiu, Hsiu-Ching; Halaki, Mark; O'Dwyer, Nicholas

2013-04-30

Most previous studies of associated reactions (ARs) in people with cerebral palsy have used observation scales, such as recording the degree of movement through observation. The sensitive quantitative method can detect ARs that are not amply visible. The aim of this study was to provide quantitative measures of ARs during a visual pursuit position tracking task. Twenty-three hemiplegia (H) (mean +/- SD: 21y 8m +/- 11y 10m), twelve quadriplegia (Q) (21y 5m +/- 10y 3m) and twenty-two subjects with normal development (N) (21y 2m +/- 10y 10m) participated in the study. An upper limb visual pursuit tracking task was used to study ARs. The participants were required to follow a moving target with a response cursor via elbow flexion and extension movements. The occurrence of ARs was quantified by the overall coherence between the movements of tracking and non-tracking limbs and the amount of movement due to ARs was quantified by the amplitude of movement the non-tracking limbs. The amplitude of movement of the non-tracking limb indicated that the amount of ARs was larger in the Q group than the H and N groups with no significant differences between the H and N groups. The amplitude of movement of the non-tracking limb was larger during non-dominant than dominant tracking in all three groups. Some movements in the non-tracking limb were correlated with the tracking limb (correlated ARs) and some movements that were not correlated with the tracking limb (uncorrelated ARs). The correlated ARs comprised less than 40% of the total ARs for all three groups. Correlated ARs were negatively associated with clinical evaluations, but not the uncorrelated ARs. The correlated and uncorrelated ARs appear to have different relationships with clinical evaluations, implying the effect of ARs on upper limb activities could be varied.

Comparison of smooth pursuit and combined eye-head tracking in human subjects with deficient labyrinthine function

NASA Technical Reports Server (NTRS)

Leigh, R. J.; Thurston, S. E.; Sharpe, J. A.; Ranalli, P. J.; Hamid, M. A.

1987-01-01

The effects of deficient labyrinthine function on smooth visual tracking with the eyes and head were investigated, using ten patients with bilateral peripheral vestibular disease and ten normal controls. Active, combined eye-head tracking (EHT) was significantly better in patients than smooth pursuit with the eyes alone, whereas normal subjects pursued equally well in both cases. Compensatory eye movements during active head rotation in darkness were always less in patients than in normal subjects. These data were used to examine current hypotheses that postulate central cancellation of the vestibulo-ocular reflex (VOR) during EHT. A model that proposes summation of an integral smooth pursuit command and VOR/compensatory eye movements is consistent with the findings. Observation of passive EHT (visual fixation of a head-fixed target during en bloc rotation) appears to indicate that in this mode parametric gain changes contribute to modulation of the VOR.

Sinusoidal visuomotor tracking: intermittent servo-control or coupled oscillations?

PubMed

Russell, D M; Sternad, D

2001-12-01

In visuomotor tasks that involve accuracy demands, small directional changes in the trajectories have been taken as evidence of feedback-based error corrections. In the present study variability, or intermittency, in visuomanual tracking of sinusoidal targets was investigated. Two lines of analyses were pursued: First, the hypothesis that humans fundamentally act as intermittent servo-controllers was re-examined, probing the question of whether discontinuities in the movement trajectory directly imply intermittent control. Second, an alternative hypothesis was evaluated: that rhythmic tracking movements are generated by entrainment between the oscillations of the target and the actor, such that intermittency expresses the degree of stability. In 2 experiments, participants (N = 6 in each experiment) swung 1 of 2 different hand-held pendulums, tracking a rhythmic target that oscillated at different frequencies with a constant amplitude. In 1 line of analyses, the authors tested the intermittency hypothesis by using the typical kinematic error measures and spectral analysis. In a 2nd line, they examined relative phase and its variability, following analyses of rhythmic interlimb coordination. The results showed that visually guided corrective processes play a role, especially for slow movements. Intermittency, assessed as frequency and power components of the movement trajectory, was found to change as a function of both target frequency and the manipulandum's inertia. Support for entrainment was found in conditions in which task frequency was identical to or higher than the effector's eigenfrequency. The results suggest that it is the symmetry between task and effector that determines which behavioral regime is dominant.

Evaluation of Real-Time Hand Motion Tracking Using a Range Camera and the Mean-Shift Algorithm

NASA Astrophysics Data System (ADS)

Lahamy, H.; Lichti, D.

2011-09-01

Several sensors have been tested for improving the interaction between humans and machines including traditional web cameras, special gloves, haptic devices, cameras providing stereo pairs of images and range cameras. Meanwhile, several methods are described in the literature for tracking hand motion: the Kalman filter, the mean-shift algorithm and the condensation algorithm. In this research, the combination of a range camera and the simple version of the mean-shift algorithm has been evaluated for its capability for hand motion tracking. The evaluation was assessed in terms of position accuracy of the tracking trajectory in x, y and z directions in the camera space and the time difference between image acquisition and image display. Three parameters have been analyzed regarding their influence on the tracking process: the speed of the hand movement, the distance between the camera and the hand and finally the integration time of the camera. Prior to the evaluation, the required warm-up time of the camera has been measured. This study has demonstrated the suitability of the range camera used in combination with the mean-shift algorithm for real-time hand motion tracking but for very high speed hand movement in the traverse plane with respect to the camera, the tracking accuracy is low and requires improvement.

Oculomatic: High speed, reliable, and accurate open-source eye tracking for humans and non-human primates.

PubMed

Zimmermann, Jan; Vazquez, Yuriria; Glimcher, Paul W; Pesaran, Bijan; Louie, Kenway

2016-09-01

Video-based noninvasive eye trackers are an extremely useful tool for many areas of research. Many open-source eye trackers are available but current open-source systems are not designed to track eye movements with the temporal resolution required to investigate the mechanisms of oculomotor behavior. Commercial systems are available but employ closed source hardware and software and are relatively expensive, limiting wide-spread use. Here we present Oculomatic, an open-source software and modular hardware solution to eye tracking for use in humans and non-human primates. Oculomatic features high temporal resolution (up to 600Hz), real-time eye tracking with high spatial accuracy (<0.5°), and low system latency (∼1.8ms, 0.32ms STD) at a relatively low-cost. Oculomatic compares favorably to our existing scleral search-coil system while being fully non invasive. We propose that Oculomatic can support a wide range of research into the properties and neural mechanisms of oculomotor behavior. Copyright © 2016 Elsevier B.V. All rights reserved.

Rhythmic neural activity indicates the contribution of attention and memory to the processing of occluded movements in 10-month-old infants.

PubMed

Bache, Cathleen; Kopp, Franziska; Springer, Anne; Stadler, Waltraud; Lindenberger, Ulman; Werkle-Bergner, Markus

2015-11-01

Infants possess the remarkable capacity to perceive occluded movements as ongoing and coherent. Little is known about the neural mechanisms that enable internal representation of conspecifics' and inanimate objects' movements during visual occlusion. In this study, 10-month-old infants watched briefly occluded human and object movements. Prior to occlusion, continuous and distorted versions of the movement were shown. EEG recordings were used to assess neural activity assumed to relate to processes of attention (occipital alpha), memory (frontal theta), and sensorimotor simulation (central alpha) before, during, and after occlusion. Oscillatory activity was analyzed using an individualized data approach taking idiosyncrasies into account. Results for occipital alpha were consistent with infants' preference for attending to social stimuli. Furthermore, frontal theta activity was more pronounced when tracking distorted as opposed to continuous movement, and when maintaining object as opposed to human movement. Central alpha did not discriminate between experimental conditions. In sum, we conclude that observing occluded movements recruits processes of attention and memory which are modulated by stimulus and movement properties. Copyright © 2015 Elsevier B.V. All rights reserved.

Action perception as hypothesis testing.

PubMed

Donnarumma, Francesco; Costantini, Marcello; Ambrosini, Ettore; Friston, Karl; Pezzulo, Giovanni

2017-04-01

We present a novel computational model that describes action perception as an active inferential process that combines motor prediction (the reuse of our own motor system to predict perceived movements) and hypothesis testing (the use of eye movements to disambiguate amongst hypotheses). The system uses a generative model of how (arm and hand) actions are performed to generate hypothesis-specific visual predictions, and directs saccades to the most informative places of the visual scene to test these predictions - and underlying hypotheses. We test the model using eye movement data from a human action observation study. In both the human study and our model, saccades are proactive whenever context affords accurate action prediction; but uncertainty induces a more reactive gaze strategy, via tracking the observed movements. Our model offers a novel perspective on action observation that highlights its active nature based on prediction dynamics and hypothesis testing. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Experimental Evaluation of an Invasive Medical Instrument Based on a Displacement Measurement System.

PubMed

Fotiadis, Dimitris A; Astaras, Alexandros; Bamidis, Panagiotis D; Papathanasiou, Kostas; Kalfas, Anestis

2015-09-01

This paper presents a novel method for tracking the position of a medical instrument's tip. The system is based on phase locking a high frequency signal transmitted from the medical instrument's tip to a reference signal. Displacement measurement is established having the loop open, in order to get a low frequency voltage representing the medical instrument's movement; therefore, positioning is established by means of conventional measuring techniques. The voltage-controlled oscillator stage of the phase-locked loop (PLL), combined to an appropriate antenna, comprises the associated transmitter located inside the medical instrument tip. All the other low frequency PLL components, low noise amplifier and mixer, are located outside the human body, forming the receiver part of the system. The operating details of the proposed system were coded in Verilog-AMS. Simulation results indicate robust medical instrument tracking in 1-D. Experimental evaluation of the proposed position tracking system is also presented. The experiments described in this paper are based on a transmitter moving opposite a stationary receiver performing either constant velocity or uniformly accelerated movement, and also together with two stationary receivers performing constant velocity movement again. This latter setup is implemented in order to demonstrate the prototype's accuracy for planar (2-D) motion measurements. Error analysis and time-domain analysis are presented for system performance characterization. Furthermore, preliminary experimental assessment using a saline solution container to more closely approximate the human body as a radio frequency wave transmission medium has proved the system's capability of operating underneath the skin.

Motion tracing system for ultrasound guided HIFU

NASA Astrophysics Data System (ADS)

Xiao, Xu; Jiang, Tingyi; Corner, George; Huang, Zhihong

2017-03-01

One main limitation in HIFU treatment is the abdominal movement in liver and kidney caused by respiration. The study has set up a tracking model which mainly compromises of a target carrying box and a motion driving balloon. A real-time B-mode ultrasound guidance method suitable for tracking of the abdominal organ motion in 2D was established and tested. For the setup, the phantoms mimicking moving organs are carefully prepared with agar surrounding round-shaped egg-white as the target of focused ultrasound ablation. Physiological phantoms and animal tissues are driven moving reciprocally along the main axial direction of the ultrasound image probe with slightly motion perpendicular to the axial direction. The moving speed and range could be adjusted by controlling the inflation and deflation speed and amount of the balloon driven by a medical ventilator. A 6-DOF robotic arm was used to position the focused ultrasound transducer. The overall system was trying to estimate to simulate the actual movement caused by human respiration. HIFU ablation experiments using phantoms and animal organs were conducted to test the tracking effect. Ultrasound strain elastography was used to post estimate the efficiency of the tracking algorithms and system. In moving state, the axial size of the lesion (perpendicular to the movement direction) are averagely 4mm, which is one third larger than the lesion got when the target was not moving. This presents the possibility of developing a low-cost real-time method of tracking organ motion during HIFU treatment in liver or kidney.

Accuracy of a Real-Time, Computerized, Binocular, Three-Dimensional Trajectory-Tracking Device for Recording Functional Mandibular Movements

PubMed Central

Zhao, Tian; Yang, Huifang; Sui, Huaxin; Salvi, Satyajeet Sudhir; Wang, Yong; Sun, Yuchun

2016-01-01

Objective Developments in digital technology have permitted researchers to study mandibular movements. Here, the accuracy of a real-time, computerized, binocular, three-dimensional (3D) trajectory-tracking device for recording functional mandibular movements was evaluated. Methods An occlusal splint without the occlusal region was created based on a plaster cast of the lower dentition. The splint was rigidly connected with a target on its labial side and seated on the cast. The cast was then rigidly attached to the stage of a high-precision triaxial electronic translator, which was used to move the target-cast-stage complex. Half-circular movements (5.00-mm radius) in three planes (XOY, XOZ, YOZ) and linear movements along the x-axis were performed at 5.00 mm/s. All trajectory points were recorded with the binocular 3D trajectory-tracking device and fitted to arcs or lines, respectively, with the Imageware software. To analyze the accuracy of the trajectory-tracking device, the mean distances between the trajectory points and the fitted arcs or lines were measured, and the mean differences between the lengths of the fitted arcs’ radii and a set value (5.00 mm) were then calculated. A one-way analysis of variance was used to evaluate the spatial consistency of the recording accuracy in three different planes. Results The mean distances between the trajectory points and fitted arcs or lines were 0.076 ± 0.033 mm or 0.089 ± 0.014 mm. The mean difference between the lengths of the fitted arcs’ radii and the set value (5.00 mm) was 0.025 ± 0.071 mm. A one-way ANOVA showed that the recording errors in three different planes were not statistically significant. Conclusion These results suggest that the device can record certain movements at 5.00 mm/s, which is similar to the speed of functional mandibular movements. In addition, the recordings had an error of <0.1 mm and good spatial consistency. Thus, the device meets some of the requirements necessary for recording human mandibular movements. PMID:27701462

Real Time 3D Facial Movement Tracking Using a Monocular Camera

PubMed Central

Dong, Yanchao; Wang, Yanming; Yue, Jiguang; Hu, Zhencheng

2016-01-01

The paper proposes a robust framework for 3D facial movement tracking in real time using a monocular camera. It is designed to estimate the 3D face pose and local facial animation such as eyelid movement and mouth movement. The framework firstly utilizes the Discriminative Shape Regression method to locate the facial feature points on the 2D image and fuses the 2D data with a 3D face model using Extended Kalman Filter to yield 3D facial movement information. An alternating optimizing strategy is adopted to fit to different persons automatically. Experiments show that the proposed framework could track the 3D facial movement across various poses and illumination conditions. Given the real face scale the framework could track the eyelid with an error of 1 mm and mouth with an error of 2 mm. The tracking result is reliable for expression analysis or mental state inference. PMID:27463714

Real Time 3D Facial Movement Tracking Using a Monocular Camera.

PubMed

Dong, Yanchao; Wang, Yanming; Yue, Jiguang; Hu, Zhencheng

2016-07-25

The paper proposes a robust framework for 3D facial movement tracking in real time using a monocular camera. It is designed to estimate the 3D face pose and local facial animation such as eyelid movement and mouth movement. The framework firstly utilizes the Discriminative Shape Regression method to locate the facial feature points on the 2D image and fuses the 2D data with a 3D face model using Extended Kalman Filter to yield 3D facial movement information. An alternating optimizing strategy is adopted to fit to different persons automatically. Experiments show that the proposed framework could track the 3D facial movement across various poses and illumination conditions. Given the real face scale the framework could track the eyelid with an error of 1 mm and mouth with an error of 2 mm. The tracking result is reliable for expression analysis or mental state inference.

Extracting information of fixational eye movements through pupil tracking

NASA Astrophysics Data System (ADS)

Xiao, JiangWei; Qiu, Jian; Luo, Kaiqin; Peng, Li; Han, Peng

2018-01-01

Human eyes are never completely static even when they are fixing a stationary point. These irregular, small movements, which consist of micro-tremors, micro-saccades and drifts, can prevent the fading of the images that enter our eyes. The importance of researching the fixational eye movements has been experimentally demonstrated recently. However, the characteristics of fixational eye movements and their roles in visual process have not been explained clearly, because these signals can hardly be completely extracted by now. In this paper, we developed a new eye movement detection device with a high-speed camera. This device includes a beam splitter mirror, an infrared light source and a high-speed digital video camera with a frame rate of 200Hz. To avoid the influence of head shaking, we made the device wearable by fixing the camera on a safety helmet. Using this device, the experiments of pupil tracking were conducted. By localizing the pupil center and spectrum analysis, the envelope frequency spectrum of micro-saccades, micro-tremors and drifts are shown obviously. The experimental results show that the device is feasible and effective, so that the device can be applied in further characteristic analysis.

Implementation of Fractal Dimension and Self-Organizing Map to Detect Toxic Effects of Toluene on Movement Tracks of Daphnia magna.

PubMed

Liu, Yuedan; Xia, Chunlei; Fan, Zhongya; Wu, Renren; Chen, Xianglin; Liu, Zuoyi

2018-01-01

Movement behaviors of an indicator species, Daphnia magna , in response to contaminants have been implemented to monitor environmental disturbances. Complexity in movement tracks of Daphnia magna was characterized by use of fractal dimension and self-organizing map. The individual movement tracks of D. magna were continuously recorded for 24 hours before and after treatments with toluene at the concentration of 10 mg/L, respectively. The general complexity in movement tracks (10 minutes) was characterized by fractal dimension. Results showed that average fractal dimension of movement tracks was decreased from 1.62 to 1.22 after treatments. The instantaneous movement parameters of movement segments in 5 s were input into the self-organizing map to investigate the swimming pattern changes under stresses of toluene. Abnormal behaviors of D. magna are more frequently observed after treatments than before treatments. Computational methods in ecological informatics could be utilized to obtain the useful information in behavioral data of D. magna and would be further applied as an in situ monitoring tool in water environment.

Whole-Body Human Inverse Dynamics with Distributed Micro-Accelerometers, Gyros and Force Sensing †

PubMed Central

Latella, Claudia; Kuppuswamy, Naveen; Romano, Francesco; Traversaro, Silvio; Nori, Francesco

2016-01-01

Human motion tracking is a powerful tool used in a large range of applications that require human movement analysis. Although it is a well-established technique, its main limitation is the lack of estimation of real-time kinetics information such as forces and torques during the motion capture. In this paper, we present a novel approach for a human soft wearable force tracking for the simultaneous estimation of whole-body forces along with the motion. The early stage of our framework encompasses traditional passive marker based methods, inertial and contact force sensor modalities and harnesses a probabilistic computational technique for estimating dynamic quantities, originally proposed in the domain of humanoid robot control. We present experimental analysis on subjects performing a two degrees-of-freedom bowing task, and we estimate the motion and kinetics quantities. The results demonstrate the validity of the proposed method. We discuss the possible use of this technique in the design of a novel soft wearable force tracking device and its potential applications. PMID:27213394

Using eye tracking to identify faking attempts during penile plethysmography assessment.

PubMed

Trottier, Dominique; Rouleau, Joanne-Lucine; Renaud, Patrice; Goyette, Mathieu

2014-01-01

Penile plethysmography (PPG) is considered the most rigorous method for sexual interest assessment. Nevertheless, it is subject to faking attempts by participants, which compromises the internal validity of the instrument. To date, various attempts have been made to limit voluntary control of sexual response during PPG assessments, without satisfactory results. This exploratory research examined eye-tracking technologies' ability to identify the presence of cognitive strategies responsible for erectile inhibition during PPG assessment. Eye movements and penile responses for 20 subjects were recorded while exploring animated human-like computer-generated stimuli in a virtual environment under three distinct viewing conditions: (a) the free visual exploration of a preferred sexual stimulus without erectile inhibition; (b) the viewing of a preferred sexual stimulus with erectile inhibition; and (c) the free visual exploration of a non-preferred sexual stimulus. Results suggest that attempts to control erectile responses generate specific eye-movement variations, characterized by a general deceleration of the exploration process and limited exploration of the erogenous zone. Findings indicate that recording eye movements can provide significant information on the presence of competing covert processes responsible for erectile inhibition. The use of eye-tracking technologies during PPG could therefore lead to improved internal validity of the plethysmographic procedure.

Quantifying gaze and mouse interactions on spatial visual interfaces with a new movement analytics methodology

PubMed Central

2017-01-01

Eye movements provide insights into what people pay attention to, and therefore are commonly included in a variety of human-computer interaction studies. Eye movement recording devices (eye trackers) produce gaze trajectories, that is, sequences of gaze location on the screen. Despite recent technological developments that enabled more affordable hardware, gaze data are still costly and time consuming to collect, therefore some propose using mouse movements instead. These are easy to collect automatically and on a large scale. If and how these two movement types are linked, however, is less clear and highly debated. We address this problem in two ways. First, we introduce a new movement analytics methodology to quantify the level of dynamic interaction between the gaze and the mouse pointer on the screen. Our method uses volumetric representation of movement, the space-time densities, which allows us to calculate interaction levels between two physically different types of movement. We describe the method and compare the results with existing dynamic interaction methods from movement ecology. The sensitivity to method parameters is evaluated on simulated trajectories where we can control interaction levels. Second, we perform an experiment with eye and mouse tracking to generate real data with real levels of interaction, to apply and test our new methodology on a real case. Further, as our experiment tasks mimics route-tracing when using a map, it is more than a data collection exercise and it simultaneously allows us to investigate the actual connection between the eye and the mouse. We find that there seem to be natural coupling when eyes are not under conscious control, but that this coupling breaks down when instructed to move them intentionally. Based on these observations, we tentatively suggest that for natural tracing tasks, mouse tracking could potentially provide similar information as eye-tracking and therefore be used as a proxy for attention. However, more research is needed to confirm this. PMID:28777822

Quantifying gaze and mouse interactions on spatial visual interfaces with a new movement analytics methodology.

PubMed

Demšar, Urška; Çöltekin, Arzu

2017-01-01

Eye movements provide insights into what people pay attention to, and therefore are commonly included in a variety of human-computer interaction studies. Eye movement recording devices (eye trackers) produce gaze trajectories, that is, sequences of gaze location on the screen. Despite recent technological developments that enabled more affordable hardware, gaze data are still costly and time consuming to collect, therefore some propose using mouse movements instead. These are easy to collect automatically and on a large scale. If and how these two movement types are linked, however, is less clear and highly debated. We address this problem in two ways. First, we introduce a new movement analytics methodology to quantify the level of dynamic interaction between the gaze and the mouse pointer on the screen. Our method uses volumetric representation of movement, the space-time densities, which allows us to calculate interaction levels between two physically different types of movement. We describe the method and compare the results with existing dynamic interaction methods from movement ecology. The sensitivity to method parameters is evaluated on simulated trajectories where we can control interaction levels. Second, we perform an experiment with eye and mouse tracking to generate real data with real levels of interaction, to apply and test our new methodology on a real case. Further, as our experiment tasks mimics route-tracing when using a map, it is more than a data collection exercise and it simultaneously allows us to investigate the actual connection between the eye and the mouse. We find that there seem to be natural coupling when eyes are not under conscious control, but that this coupling breaks down when instructed to move them intentionally. Based on these observations, we tentatively suggest that for natural tracing tasks, mouse tracking could potentially provide similar information as eye-tracking and therefore be used as a proxy for attention. However, more research is needed to confirm this.

The effect of concurrent hand movement on estimated time to contact in a prediction motion task.

PubMed

Zheng, Ran; Maraj, Brian K V

2018-04-27

In many activities, we need to predict the arrival of an occluded object. This action is called prediction motion or motion extrapolation. Previous researchers have found that both eye tracking and the internal clocking model are involved in the prediction motion task. Additionally, it is reported that concurrent hand movement facilitates the eye tracking of an externally generated target in a tracking task, even if the target is occluded. The present study examined the effect of concurrent hand movement on the estimated time to contact in a prediction motion task. We found different (accurate/inaccurate) concurrent hand movements had the opposite effect on the eye tracking accuracy and estimated TTC in the prediction motion task. That is, the accurate concurrent hand tracking enhanced eye tracking accuracy and had the trend to increase the precision of estimated TTC, but the inaccurate concurrent hand tracking decreased eye tracking accuracy and disrupted estimated TTC. However, eye tracking accuracy does not determine the precision of estimated TTC.

Research into automatic recognition of joints in human symmetrical movements

NASA Astrophysics Data System (ADS)

Fan, Yifang; Li, Zhiyu

2008-03-01

High speed photography is a major means of collecting data from human body movement. It enables the automatic identification of joints, which brings great significance to the research, treatment and recovery of injuries, the analysis to the diagnosis of sport techniques and the ergonomics. According to the features that when the adjacent joints of human body are in planetary motion, their distance remains the same, and according to the human body joint movement laws (such as the territory of the articular anatomy and the kinematic features), a new approach is introduced to process the image thresholding of joints filmed by the high speed camera, to automatically identify the joints and to automatically trace the joint points (by labeling markers at the joints). Based upon the closure of marking points, automatic identification can be achieved through thresholding treatment. Due to the screening frequency and the laws of human segment movement, when the marking points have been initialized, their automatic tracking can be achieved with the progressive sequential images.Then the testing results, the data from three-dimensional force platform and the characteristics that human body segment will only rotate around the closer ending segment when the segment has no boding force and only valid to the conservative force all tell that after being analyzed kinematically, the approach is approved to be valid.

Eye-Hand Synergy and Intermittent Behaviors during Target-Directed Tracking with Visual and Non-visual Information

PubMed Central

Huang, Chien-Ting; Hwang, Ing-Shiou

2012-01-01

Visual feedback and non-visual information play different roles in tracking of an external target. This study explored the respective roles of the visual and non-visual information in eleven healthy volunteers who coupled the manual cursor to a rhythmically moving target of 0.5 Hz under three sensorimotor conditions: eye-alone tracking (EA), eye-hand tracking with visual feedback of manual outputs (EH tracking), and the same tracking without such feedback (EHM tracking). Tracking error, kinematic variables, and movement intermittency (saccade and speed pulse) were contrasted among tracking conditions. The results showed that EHM tracking exhibited larger pursuit gain, less tracking error, and less movement intermittency for the ocular plant than EA tracking. With the vision of manual cursor, EH tracking achieved superior tracking congruency of the ocular and manual effectors with smaller movement intermittency than EHM tracking, except that the rate precision of manual action was similar for both types of tracking. The present study demonstrated that visibility of manual consequences altered mutual relationships between movement intermittency and tracking error. The speed pulse metrics of manual output were linked to ocular tracking error, and saccade events were time-locked to the positional error of manual tracking during EH tracking. In conclusion, peripheral non-visual information is critical to smooth pursuit characteristics and rate control of rhythmic manual tracking. Visual information adds to eye-hand synchrony, underlying improved amplitude control and elaborate error interpretation during oculo-manual tracking. PMID:23236498

Real Time Eye Tracking and Hand Tracking Using Regular Video Cameras for Human Computer Interaction

DTIC Science & Technology

2011-01-01

Paperwork Reduction Project (0704-0188) Washington, DC 20503. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) January...understand us. More specifically, the computer should be able to infer what we wish to see, do , and interact with through our movements, gestures, and...in depth freedom. Our system differs from the majority of other systems in that we do not use infrared, stereo-cameras, specially-constructed

Low-Cost Radar Sensors for Personnel Detection and Tracking in Urban Areas

DTIC Science & Technology

2007-01-31

progress on the reserach grant "Low-Cost Radar Sensors for Personnel Detection and Tracking in Urban Areas" during the period 1 May 2005 - 31 December...the DOA of target i with respect to the array boresight is given by: O 1sin-1 -/- fD)--F2(. )(1) where d is the spacing between the elements and A, is...wall. A large database was collected for different parameter spaces including number of humans, types of movements, wall types and radar polarization

Our self-tracking movement and health literacy: are we really making every moment count?

PubMed

Vamos, Sandra; Klein, Klaus

2016-08-03

There is a growing movement related to self-tracking in the quest for better health. Why do so many people like to use 'intelligent tools' like shiny sensors or mobile apps to keep an eye on every move? Do they really help us drive sustained healthy behavioral changes? Despite technological advances and product promises, we must remember that technology alone does not facilitate change to optimize health benefits. The purpose of the commentary is to pose the question: How 'health literate' do we have to be to reap the actionable health benefits of self-tracking? Research has revealed the prevalence of limited health literacy across the globe. Health literacy involves a complex set of inter-connected skills, including acting upon health information. This commentary puts attention on health literacy as an essential human tool to better equip people to overcome barriers and use devices to leverage their full potential. © The Author(s) 2016.

Eye Movements during Multiple Object Tracking: Where Do Participants Look?

ERIC Educational Resources Information Center

Fehd, Hilda M.; Seiffert, Adriane E.

2008-01-01

Similar to the eye movements you might make when viewing a sports game, this experiment investigated where participants tend to look while keeping track of multiple objects. While eye movements were recorded, participants tracked either 1 or 3 of 8 red dots that moved randomly within a square box on a black background. Results indicated that…

Human body motion tracking based on quantum-inspired immune cloning algorithm

NASA Astrophysics Data System (ADS)

Han, Hong; Yue, Lichuan; Jiao, Licheng; Wu, Xing

2009-10-01

In a static monocular camera system, to gain a perfect 3D human body posture is a great challenge for Computer Vision technology now. This paper presented human postures recognition from video sequences using the Quantum-Inspired Immune Cloning Algorithm (QICA). The algorithm included three parts. Firstly, prior knowledge of human beings was used, the key joint points of human could be detected automatically from the human contours and skeletons which could be thinning from the contours; And due to the complexity of human movement, a forecasting mechanism of occlusion joint points was addressed to get optimum 2D key joint points of human body; And then pose estimation recovered by optimizing between the 2D projection of 3D human key joint points and 2D detection key joint points using QICA, which recovered the movement of human body perfectly, because this algorithm could acquire not only the global optimal solution, but the local optimal solution.

Trackable life: Data, sequence, and organism in movement ecology.

PubMed

Benson, Etienne S

2016-06-01

Over the past decade an increasing number of ecologists have begun to frame their work as a contribution to the emerging research field of movement ecology. This field's primary object of research is the movement track, which is usually operationalized as a series of discrete "steps and stops" that represent a portion of an animal's "lifetime track." Its practitioners understand their field as dependent on recent technical advances in tracking organisms and analyzing their movements. By making movement their primary object of research, rather than simply an expression of deeper biological phenomena, movement ecologists are able to generalize across the movement patterns of a wide variety of species and to draw on statistical techniques developed to model the movements of non-living things. Although it can trace its roots back to a long tradition of statistical models of movement, the field relies heavily on metaphors from genomics; in particular, movement tracks have been seen as similar to DNA sequences. Though this has helped movement ecology consolidate around a shared understanding of movement, the field may need to broaden its understanding of movement beyond the sequence if it is to realize its potential to address urgent concerns such as biodiversity loss. Copyright © 2016 Elsevier Ltd. All rights reserved.

Passive acoustic tracking of singing humpback whales (Megaptera novaeangliae) on a northwest Atlantic feeding ground.

PubMed

Stanistreet, Joy E; Risch, Denise; Van Parijs, Sofie M

2013-01-01

Passive acoustic tracking provides an unobtrusive method of studying the movement of sound-producing animals in the marine environment where traditional tracking methods may be costly or infeasible. We used passive acoustic tracking to characterize the fine-scale movements of singing humpback whales (Megaptera novaeangliae) on a northwest Atlantic feeding ground. Male humpback whales produce complex songs, a phenomenon that is well documented in tropical regions during the winter breeding season, but also occurs at higher latitudes during other times of year. Acoustic recordings were made throughout 2009 using an array of autonomous recording units deployed in the Stellwagen Bank National Marine Sanctuary. Song was recorded during spring and fall, and individual singing whales were localized and tracked throughout the array using a correlation sum estimation method on the time-synchronized recordings. Tracks were constructed for forty-three song sessions, revealing a high level of variation in movement patterns in both the spring and fall seasons, ranging from slow meandering to faster directional movement. Tracks were 30 min to 8 h in duration, and singers traveled distances ranging from 0.9 to 20.1 km. Mean swimming speed was 2.06 km/h (SD 0.95). Patterns and rates of movement indicated that most singers were actively swimming. In one case, two singers were tracked simultaneously, revealing a potential acoustic interaction. Our results provide a first description of the movements of singers on a northwest Atlantic feeding ground, and demonstrate the utility of passive acoustic tracking for studying the fine-scale movements of cetaceans within the behavioral context of their calls. These methods have further applications for conservation and management purposes, particularly by enhancing our ability to estimate cetacean densities using passive acoustic monitoring.

Passive Acoustic Tracking of Singing Humpback Whales (Megaptera novaeangliae) on a Northwest Atlantic Feeding Ground

PubMed Central

Stanistreet, Joy E.; Risch, Denise; Van Parijs, Sofie M.

2013-01-01

Passive acoustic tracking provides an unobtrusive method of studying the movement of sound-producing animals in the marine environment where traditional tracking methods may be costly or infeasible. We used passive acoustic tracking to characterize the fine-scale movements of singing humpback whales (Megaptera novaeangliae) on a northwest Atlantic feeding ground. Male humpback whales produce complex songs, a phenomenon that is well documented in tropical regions during the winter breeding season, but also occurs at higher latitudes during other times of year. Acoustic recordings were made throughout 2009 using an array of autonomous recording units deployed in the Stellwagen Bank National Marine Sanctuary. Song was recorded during spring and fall, and individual singing whales were localized and tracked throughout the array using a correlation sum estimation method on the time-synchronized recordings. Tracks were constructed for forty-three song sessions, revealing a high level of variation in movement patterns in both the spring and fall seasons, ranging from slow meandering to faster directional movement. Tracks were 30 min to 8 h in duration, and singers traveled distances ranging from 0.9 to 20.1 km. Mean swimming speed was 2.06 km/h (SD 0.95). Patterns and rates of movement indicated that most singers were actively swimming. In one case, two singers were tracked simultaneously, revealing a potential acoustic interaction. Our results provide a first description of the movements of singers on a northwest Atlantic feeding ground, and demonstrate the utility of passive acoustic tracking for studying the fine-scale movements of cetaceans within the behavioral context of their calls. These methods have further applications for conservation and management purposes, particularly by enhancing our ability to estimate cetacean densities using passive acoustic monitoring. PMID:23593447

Using sutures to attach miniature tracking tags to small bats for multimonth movement and behavioral studies

Treesearch

Kevin T. Castle; Ted Weller; Paul M. Cryan; Cris D. Hein; Michael R. Schirmacher

2015-01-01

Determining the detailed movements of individual animals often requires them to carry tracking devices, but tracking broad-scale movement of small bats (<30 g) has been limited by transmitter technology and long-term attachment methods. This limitation inhibits our understanding of bat dispersal and migration, particularly in the context of emerging...

Anticipatory Eye Movements in Interleaving Templates of Human Behavior

NASA Technical Reports Server (NTRS)

Matessa, Michael

2004-01-01

Performance modeling has been made easier by architectures which package psychological theory for reuse at useful levels of abstraction. CPM-GOMS uses templates of behavior to package at a task level (e.g., mouse move-click, typing) predictions of lower-level cognitive, perceptual, and motor resource use. CPM-GOMS also has a theory for interleaving resource use between templates. One example of interleaving is anticipatory eye movements. This paper describes the use of ACT-Stitch, a framework for translating CPM-GOMS templates and interleaving theory into ACT-R, to model anticipatory eye movements in skilled behavior. The anticipatory eye movements explain performance in a well-practiced perceptual/motor task, and the interleaving theory is supported with results from an eye-tracking experiment.

Haptic communication between humans is tuned by the hard or soft mechanics of interaction

PubMed Central

Usai, Francesco; Ganesh, Gowrishankar; Sanguineti, Vittorio; Burdet, Etienne

2018-01-01

To move a hard table together, humans may coordinate by following the dominant partner’s motion [1–4], but this strategy is unsuitable for a soft mattress where the perceived forces are small. How do partners readily coordinate in such differing interaction dynamics? To address this, we investigated how pairs tracked a target using flexion-extension of their wrists, which were coupled by a hard, medium or soft virtual elastic band. Tracking performance monotonically increased with a stiffer band for the worse partner, who had higher tracking error, at the cost of the skilled partner’s muscular effort. This suggests that the worse partner followed the skilled one’s lead, but simulations show that the results are better explained by a model where partners share movement goals through the forces, whilst the coupling dynamics determine the capacity of communicable information. This model elucidates the versatile mechanism by which humans can coordinate during both hard and soft physical interactions to ensure maximum performance with minimal effort. PMID:29565966

Feature tracking for automated volume of interest stabilization on 4D-OCT images

NASA Astrophysics Data System (ADS)

Laves, Max-Heinrich; Schoob, Andreas; Kahrs, Lüder A.; Pfeiffer, Tom; Huber, Robert; Ortmaier, Tobias

2017-03-01

A common representation of volumetric medical image data is the triplanar view (TV), in which the surgeon manually selects slices showing the anatomical structure of interest. In addition to common medical imaging such as MRI or computed tomography, recent advances in the field of optical coherence tomography (OCT) have enabled live processing and volumetric rendering of four-dimensional images of the human body. Due to the region of interest undergoing motion, it is challenging for the surgeon to simultaneously keep track of an object by continuously adjusting the TV to desired slices. To select these slices in subsequent frames automatically, it is necessary to track movements of the volume of interest (VOI). This has not been addressed with respect to 4DOCT images yet. Therefore, this paper evaluates motion tracking by applying state-of-the-art tracking schemes on maximum intensity projections (MIP) of 4D-OCT images. Estimated VOI location is used to conveniently show corresponding slices and to improve the MIPs by calculating thin-slab MIPs. Tracking performances are evaluated on an in-vivo sequence of human skin, captured at 26 volumes per second. Among investigated tracking schemes, our recently presented tracking scheme for soft tissue motion provides highest accuracy with an error of under 2.2 voxels for the first 80 volumes. Object tracking on 4D-OCT images enables its use for sub-epithelial tracking of microvessels for image-guidance.

Symmetrical Location Characteristics of Corticospinal Tract Associated With Hand Movement in the Human Brain: A Probabilistic Diffusion Tensor Tractography.

PubMed

Lee, Dong-Hoon; Lee, Do-Wan; Han, Bong-Soo

2016-04-01

The purpose of this study is to elucidate the symmetrical characteristics of corticospinal tract (CST) related with hand movement in bilateral hemispheres using probabilistic fiber tracking method. Seventeen subjects were participated in this study. Fiber tracking was performed with 2 regions of interest, hand activated functional magnetic resonance imaging (fMRI) results and pontomedullary junction in each cerebral hemisphere. Each subject's extracted fiber tract was normalized with a brain template. To measure the symmetrical distributions of the CST related with hand movement, the laterality and anteriority indices were defined in upper corona radiata (CR), lower CR, and posterior limb of internal capsule. The measured laterality and anteriority indices between the hemispheres in each different brain location showed no significant differences with P < 0.05. There were significant differences in the measured indices among 3 different brain locations in each cerebral hemisphere with P < 0.001. Our results clearly showed that the hand CST had symmetric structures in bilateral hemispheres. The probabilistic fiber tracking with fMRI approach demonstrated that the hand CST can be successfully extracted regardless of crossing fiber problem. Our analytical approaches and results seem to be helpful for providing the database of CST somatotopy to neurologists and clinical researches.

Tracking, Ability Grouping and the Gifted. PAGE Bulletin.

ERIC Educational Resources Information Center

Fiedler-Brand, Ellen; Lange, Richard E.; Winebrenner, Susan

This brief bulletin addresses seven "myths" of tracking or ability grouping with gifted students in response to what is seen as a current movement against both ability grouping and tracking, which are characterized by the "anti-tracking" movement as inflexible and unaccommodating of a varied schedule. The following myths are countered: (1)…

Using movement and intentions to understand human activity.

PubMed

Zacks, Jeffrey M; Kumar, Shawn; Abrams, Richard A; Mehta, Ritesh

2009-08-01

During perception, people segment continuous activity into discrete events. They do so in part by monitoring changes in features of an ongoing activity. Characterizing these features is important for theories of event perception and may be helpful for designing information systems. The three experiments reported here asked whether the body movements of an actor predict when viewers will perceive event boundaries. Body movements were recorded using a magnetic motion tracking system and compared with viewers' segmentation of his activity into events. Changes in movement features were strongly associated with segmentation. This was more true for fine-grained than for coarse-grained boundaries, and was strengthened when the stimulus displays were reduced from live-action movies to simplified animations. These results suggest that movement variables play an important role in the process of segmenting activity into meaningful events, and that the influence of movement on segmentation depends on the availability of other information sources.

Ambulatory position and orientation tracking fusing magnetic and inertial sensing.

PubMed

Roetenberg, Daniel; Slycke, Per J; Veltink, Peter H

2007-05-01

This paper presents the design and testing of a portable magnetic system combined with miniature inertial sensors for ambulatory 6 degrees of freedom (DOF) human motion tracking. The magnetic system consists of three orthogonal coils, the source, fixed to the body and 3-D magnetic sensors, fixed to remote body segments, which measure the fields generated by the source. Based on the measured signals, a processor calculates the relative positions and orientations between source and sensor. Magnetic actuation requires a substantial amount of energy which limits the update rate with a set of batteries. Moreover, the magnetic field can easily be disturbed by ferromagnetic materials or other sources. Inertial sensors can be sampled at high rates, require only little energy and do not suffer from magnetic interferences. However, accelerometers and gyroscopes can only measure changes in position and orientation and suffer from integration drift. By combing measurements from both systems in a complementary Kalman filter structure, an optimal solution for position and orientation estimates is obtained. The magnetic system provides 6 DOF measurements at a relatively low update rate while the inertial sensors track the changes position and orientation in between the magnetic updates. The implemented system is tested against a lab-bound camera tracking system for several functional body movements. The accuracy was about 5 mm for position and 3 degrees for orientation measurements. Errors were higher during movements with high velocities due to relative movement between source and sensor within one cycle of magnetic actuation.

Gaze-contingent displays: a review.

PubMed

Duchowski, Andrew T; Cournia, Nathan; Murphy, Hunter

2004-12-01

Gaze-contingent displays (GCDs) attempt to balance the amount of information displayed against the visual information processing capacity of the observer through real-time eye movement sensing. Based on the assumed knowledge of the instantaneous location of the observer's focus of attention, GCD content can be "tuned" through several display processing means. Screen-based displays alter pixel level information generally matching the resolvability of the human retina in an effort to maximize bandwidth. Model-based displays alter geometric-level primitives along similar goals. Attentive user interfaces (AUIs) manage object- level entities (e.g., windows, applications) depending on the assumed attentive state of the observer. Such real-time display manipulation is generally achieved through non-contact, unobtrusive tracking of the observer's eye movements. This paper briefly reviews past and present display techniques as well as emerging graphics and eye tracking technology for GCD development.

Scripting human animations in a virtual environment

NASA Technical Reports Server (NTRS)

Goldsby, Michael E.; Pandya, Abhilash K.; Maida, James C.

1994-01-01

The current deficiencies of virtual environment (VE) are well known: annoying lag time in drawing the current view, drastically simplified environments to reduce that time lag, low resolution and narrow field of view. Animation scripting is an application of VE technology which can be carried out successfully despite these deficiencies. The final product is a smoothly moving high resolution animation displaying detailed models. In this system, the user is represented by a human computer model with the same body proportions. Using magnetic tracking, the motions of the model's upper torso, head and arms are controlled by the user's movements (18 degrees of freedom). The model's lower torso and global position and orientation are controlled by a spaceball and keypad (12 degrees of freedom). Using this system human motion scripts can be extracted from the user's movements while immersed in a simplified virtual environment. Recorded data is used to define key frames; motion is interpolated between them and post processing adds a more detailed environment. The result is a considerable savings in time and a much more natural-looking movement of a human figure in a smooth and seamless animation.

Tracking the Evolution of Smartphone Sensing for Monitoring Human Movement.

PubMed

del Rosario, Michael B; Redmond, Stephen J; Lovell, Nigel H

2015-07-31

Advances in mobile technology have led to the emergence of the "smartphone", a new class of device with more advanced connectivity features that have quickly made it a constant presence in our lives. Smartphones are equipped with comparatively advanced computing capabilities, a global positioning system (GPS) receivers, and sensing capabilities (i.e., an inertial measurement unit (IMU) and more recently magnetometer and barometer) which can be found in wearable ambulatory monitors (WAMs). As a result, algorithms initially developed for WAMs that "count" steps (i.e., pedometers); gauge physical activity levels; indirectly estimate energy expenditure and monitor human movement can be utilised on the smartphone. These algorithms may enable clinicians to "close the loop" by prescribing timely interventions to improve or maintain wellbeing in populations who are at risk of falling or suffer from a chronic disease whose progression is linked to a reduction in movement and mobility. The ubiquitous nature of smartphone technology makes it the ideal platform from which human movement can be remotely monitored without the expense of purchasing, and inconvenience of using, a dedicated WAM. In this paper, an overview of the sensors that can be found in the smartphone are presented, followed by a summary of the developments in this field with an emphasis on the evolution of algorithms used to classify human movement. The limitations identified in the literature will be discussed, as well as suggestions about future research directions.

Consequences of Traumatic Brain Injury for Human Vergence Dynamics

PubMed Central

Tyler, Christopher W.; Likova, Lora T.; Mineff, Kristyo N.; Elsaid, Anas M.; Nicholas, Spero C.

2015-01-01

Purpose: Traumatic brain injury involving loss of consciousness has focal effects in the human brainstem, suggesting that it may have particular consequences for eye movement control. This hypothesis was investigated by measurements of vergence eye movement parameters. Methods: Disparity vergence eye movements were measured for a population of 123 normally sighted individuals, 26 of whom had suffered diffuse traumatic brain injury (dTBI) in the past, while the remainder served as controls. Vergence tracking responses were measured to sinusoidal disparity modulation of a random-dot field. Disparity vergence step responses were characterized in terms of their dynamic parameters separately for the convergence and divergence directions. Results: The control group showed notable differences between convergence and divergence dynamics. The dTBI group showed significantly abnormal vergence behavior on many of the dynamic parameters. Conclusion: The results support the hypothesis that occult injury to the oculomotor control system is a common residual outcome of dTBI. PMID:25691880

Vestibulo-Cervico-Ocular Responses and Tracking Eye Movements after Prolonged Exposure to Microgravity

NASA Technical Reports Server (NTRS)

Kornilova, L. N.; Naumov, I. A.; Azarov, K. A.; Sagalovitch, S. V.; Reschke, Millard F.; Kozlovskaya, I. B.

2007-01-01

The vestibular function and tracking eye movements were investigated in 12 Russian crew members of ISS missions on days 1(2), 4(5-6), and 8(9-10) after prolonged exposure to microgravity (126 to 195 days). The spontaneous oculomotor activity, static torsional otolith-cervico-ocular reflex, dynamic vestibulo-cervico-ocular responses, vestibular reactivity, tracking eye movements, and gaze-holding were studied using videooculography (VOG) and electrooculography (EOG) for parallel eye movement recording. On post-flight days 1-2 (R+1-2) some cosmonauts demonstrated: - an increased spontaneous oculomotor activity (floating eye movements, spontaneous nystagmus of the typical and atypical form, square wave jerks, gaze nystagmus) with the head held in the vertical position; - suppressed otolith function (absent or reduced by one half amplitude of torsional compensatory eye counter-rolling) with the head inclined statically right- or leftward by 300; - increased vestibular reactivity (lowered threshold and increased intensity of the vestibular nystagmus) during head turns around the longitudinal body axis at 0.125 Hz; - a significant change in the accuracy, velocity, and temporal characteristics of the eye tracking. The pattern, depth, dynamics, and velocity of the vestibular function and tracking eye movements recovery varied with individual participants in the investigation. However, there were also regular responses during readaptation to the normal gravity: - suppression of the otolith function was typically accompanied by an exaggerated vestibular reactivity; - the structure of visual tracking (the accuracy of fixational eye rotations, smooth tracking, and gaze-holding) was disturbed (the appearance of correcting saccades, the transition of smooth tracking to saccadic tracking) only in those cosmonauts who, in parallel to an increased reactivity of the vestibular input, also had central changes in the oculomotor system (spontaneous nystagmus, gaze nystagmus).

Simulation of the «COSMONAUT-ROBOT» System Interaction on the Lunar Surface Based on Methods of Machine Vision and Computer Graphics

NASA Astrophysics Data System (ADS)

Kryuchkov, B. I.; Usov, V. M.; Chertopolokhov, V. A.; Ronzhin, A. L.; Karpov, A. A.

2017-05-01

Extravehicular activity (EVA) on the lunar surface, necessary for the future exploration of the Moon, involves extensive use of robots. One of the factors of safe EVA is a proper interaction between cosmonauts and robots in extreme environments. This requires a simple and natural man-machine interface, e.g. multimodal contactless interface based on recognition of gestures and cosmonaut's poses. When travelling in the "Follow Me" mode (master/slave), a robot uses onboard tools for tracking cosmonaut's position and movements, and on the basis of these data builds its itinerary. The interaction in the system "cosmonaut-robot" on the lunar surface is significantly different from that on the Earth surface. For example, a man, dressed in a space suit, has limited fine motor skills. In addition, EVA is quite tiring for the cosmonauts, and a tired human being less accurately performs movements and often makes mistakes. All this leads to new requirements for the convenient use of the man-machine interface designed for EVA. To improve the reliability and stability of human-robot communication it is necessary to provide options for duplicating commands at the task stages and gesture recognition. New tools and techniques for space missions must be examined at the first stage of works in laboratory conditions, and then in field tests (proof tests at the site of application). The article analyzes the methods of detection and tracking of movements and gesture recognition of the cosmonaut during EVA, which can be used for the design of human-machine interface. A scenario for testing these methods by constructing a virtual environment simulating EVA on the lunar surface is proposed. Simulation involves environment visualization and modeling of the use of the "vision" of the robot to track a moving cosmonaut dressed in a spacesuit.

Object motion computation for the initiation of smooth pursuit eye movements in humans.

PubMed

Wallace, Julian M; Stone, Leland S; Masson, Guillaume S

2005-04-01

Pursuing an object with smooth eye movements requires an accurate estimate of its two-dimensional (2D) trajectory. This 2D motion computation requires that different local motion measurements are extracted and combined to recover the global object-motion direction and speed. Several combination rules have been proposed such as vector averaging (VA), intersection of constraints (IOC), or 2D feature tracking (2DFT). To examine this computation, we investigated the time course of smooth pursuit eye movements driven by simple objects of different shapes. For type II diamond (where the direction of true object motion is dramatically different from the vector average of the 1-dimensional edge motions, i.e., VA not equal IOC = 2DFT), the ocular tracking is initiated in the vector average direction. Over a period of less than 300 ms, the eye-tracking direction converges on the true object motion. The reduction of the tracking error starts before the closing of the oculomotor loop. For type I diamonds (where the direction of true object motion is identical to the vector average direction, i.e., VA = IOC = 2DFT), there is no such bias. We quantified this effect by calculating the direction error between responses to types I and II and measuring its maximum value and time constant. At low contrast and high speeds, the initial bias in tracking direction is larger and takes longer to converge onto the actual object-motion direction. This effect is attenuated with the introduction of more 2D information to the extent that it was totally obliterated with a texture-filled type II diamond. These results suggest a flexible 2D computation for motion integration, which combines all available one-dimensional (edge) and 2D (feature) motion information to refine the estimate of object-motion direction over time.

Inverse Proportional Relationship Between Switching-Time Length and Fractal-Like Structure for Continuous Tracking Movement

NASA Astrophysics Data System (ADS)

Hirakawa, Takehito; Suzuki, Hiroo; Gohara, Kazutoshi; Yamamoto, Yuji

We investigate the relationship between the switching-time length T and the fractal-like feature that characterizes the behavior of dissipative dynamical systems excited by external temporal inputs for tracking movement. Seven healthy right-handed male participants were asked to continuously track light-emitting diodes that were located on the right and left sides in front of them. These movements were performed under two conditions: when the same input pattern was repeated (the periodic-input condition) and when two different input patterns were switched stochastically (the switching-input condition). The repeated time lengths of input patterns during these conditions were 2.00, 1.00, 0.75, 0.50, 0.35, and 0.25s. The movements of a lever held between a participant’s thumb and index finger were measured by a motion-capture system and were analyzed with respect to position and velocity. The condition in which the same input was repeated revealed that two different stable trajectories existed in a cylindrical state space, while the condition in which the inputs were switched induced transitions between these two trajectories. These two different trajectories were considered as excited attractors. The transitions between the two excited attractors produced eight trajectories; they were then characterized by a fractal-like feature as a third-order sequence effect. Moreover, correlation dimensions, which are typically used to evaluate fractal-like features, calculated from the set on the Poincaré section increased as the switching-time length T decreased. These results suggest that an inverse proportional relationship exists between the switching-time length T and the fractal-like feature of human movement.

Technical Report of Successful Deployment of Tandem Visual Tracking During Live Laparoscopic Cholecystectomy Between Novice and Expert Surgeon.

PubMed

Puckett, Yana; Baronia, Benedicto C

2016-09-20

With the recent advances in eye tracking technology, it is now possible to track surgeons' eye movements while engaged in a surgical task or when surgical residents practice their surgical skills. Several studies have compared eye movements of surgical experts and novices and developed techniques to assess surgical skill on the basis of eye movement utilizing simulators and live surgery. None have evaluated simultaneous visual tracking between an expert and a novice during live surgery. Here, we describe a successful simultaneous deployment of visual tracking of an expert and a novice during live laparoscopic cholecystectomy. One expert surgeon and one chief surgical resident at an accredited surgical program in Lubbock, TX, USA performed a live laparoscopic cholecystectomy while simultaneously wearing the visual tracking devices. Their visual attitudes and movements were monitored via video recordings. The recordings were then analyzed for correlation between the expert and the novice. The visual attitudes and movements correlated approximately 85% between an expert surgeon and a chief surgical resident. The surgery was carried out uneventfully, and the data was abstracted with ease. We conclude that simultaneous deployment of visual tracking during live laparoscopic surgery is a possibility. More studies and subjects are needed to verify the success of our results and obtain data analysis.

Coarse-to-fine markerless gait analysis based on PCA and Gauss-Laguerre decomposition

NASA Astrophysics Data System (ADS)

Goffredo, Michela; Schmid, Maurizio; Conforto, Silvia; Carli, Marco; Neri, Alessandro; D'Alessio, Tommaso

2005-04-01

Human movement analysis is generally performed through the utilization of marker-based systems, which allow reconstructing, with high levels of accuracy, the trajectories of markers allocated on specific points of the human body. Marker based systems, however, show some drawbacks that can be overcome by the use of video systems applying markerless techniques. In this paper, a specifically designed computer vision technique for the detection and tracking of relevant body points is presented. It is based on the Gauss-Laguerre Decomposition, and a Principal Component Analysis Technique (PCA) is used to circumscribe the region of interest. Results obtained on both synthetic and experimental tests provide significant reduction of the computational costs, with no significant reduction of the tracking accuracy.

How crawler track-mounted conveyors improve bulk handling's economics

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

Hawkins, G.P.

1984-11-01

Crawler track-mounted conveyors can be used in most applications formerly requiring stacking, reclaiming or movement from excavators to bench conveyors. The crawler track-mounted conveyor has been automated for push button operation and allows mobilization of in-pit operations for the movement of overburden, minerals and coal. In-pit mobilization of crushers, the use of mobilized steep angle conveyor for the removal of coal from the pit, and the movement of overburden from excavation to spoil can all be done more economically when a combination of a crawler track mounted conveyor is used in conjunction with a shiftable or fixed conveyor.

Predictive Simulations of Neuromuscular Coordination and Joint-Contact Loading in Human Gait.

PubMed

Lin, Yi-Chung; Walter, Jonathan P; Pandy, Marcus G

2018-04-18

We implemented direct collocation on a full-body neuromusculoskeletal model to calculate muscle forces, ground reaction forces and knee contact loading simultaneously for one cycle of human gait. A data-tracking collocation problem was solved for walking at the normal speed to establish the practicality of incorporating a 3D model of articular contact and a model of foot-ground interaction explicitly in a dynamic optimization simulation. The data-tracking solution then was used as an initial guess to solve predictive collocation problems, where novel patterns of movement were generated for walking at slow and fast speeds, independent of experimental data. The data-tracking solutions accurately reproduced joint motion, ground forces and knee contact loads measured for two total knee arthroplasty patients walking at their preferred speeds. RMS errors in joint kinematics were < 2.0° for rotations and < 0.3 cm for translations while errors in the model-computed ground-reaction and knee-contact forces were < 0.07 BW and < 0.4 BW, respectively. The predictive solutions were also consistent with joint kinematics, ground forces, knee contact loads and muscle activation patterns measured for slow and fast walking. The results demonstrate the feasibility of performing computationally-efficient, predictive, dynamic optimization simulations of movement using full-body, muscle-actuated models with realistic representations of joint function.

Affine Transform to Reform Pixel Coordinates of EOG Signals for Controlling Robot Manipulators Using Gaze Motions

PubMed Central

Rusydi, Muhammad Ilhamdi; Sasaki, Minoru; Ito, Satoshi

2014-01-01

Biosignals will play an important role in building communication between machines and humans. One of the types of biosignals that is widely used in neuroscience are electrooculography (EOG) signals. An EOG has a linear relationship with eye movement displacement. Experiments were performed to construct a gaze motion tracking method indicated by robot manipulator movements. Three operators looked at 24 target points displayed on a monitor that was 40 cm in front of them. Two channels (Ch1 and Ch2) produced EOG signals for every single eye movement. These signals were converted to pixel units by using the linear relationship between EOG signals and gaze motion distances. The conversion outcomes were actual pixel locations. An affine transform method is proposed to determine the shift of actual pixels to target pixels. This method consisted of sequences of five geometry processes, which are translation-1, rotation, translation-2, shear and dilatation. The accuracy was approximately 0.86° ± 0.67° in the horizontal direction and 0.54° ± 0.34° in the vertical. This system successfully tracked the gaze motions not only in direction, but also in distance. Using this system, three operators could operate a robot manipulator to point at some targets. This result shows that the method is reliable in building communication between humans and machines using EOGs. PMID:24919013

Hybrid markerless tracking of complex articulated motion in golf swings.

PubMed

Fung, Sim Kwoh; Sundaraj, Kenneth; Ahamed, Nizam Uddin; Kiang, Lam Chee; Nadarajah, Sivadev; Sahayadhas, Arun; Ali, Md Asraf; Islam, Md Anamul; Palaniappan, Rajkumar

2014-04-01

Sports video tracking is a research topic that has attained increasing attention due to its high commercial potential. A number of sports, including tennis, soccer, gymnastics, running, golf, badminton and cricket have been utilised to display the novel ideas in sports motion tracking. The main challenge associated with this research concerns the extraction of a highly complex articulated motion from a video scene. Our research focuses on the development of a markerless human motion tracking system that tracks the major body parts of an athlete straight from a sports broadcast video. We proposed a hybrid tracking method, which consists of a combination of three algorithms (pyramidal Lucas-Kanade optical flow (LK), normalised correlation-based template matching and background subtraction), to track the golfer's head, body, hands, shoulders, knees and feet during a full swing. We then match, track and map the results onto a 2D articulated human stick model to represent the pose of the golfer over time. Our work was tested using two video broadcasts of a golfer, and we obtained satisfactory results. The current outcomes of this research can play an important role in enhancing the performance of a golfer, provide vital information to sports medicine practitioners by providing technically sound guidance on movements and should assist to diminish the risk of golfing injuries. Copyright © 2013 Elsevier Ltd. All rights reserved.

Towards understanding addiction factors of mobile devices: An eye tracking study on effect of screen size.

PubMed

Wibirama, Sunu; Nugroho, Hanung A

2017-07-01

Mobile devices addiction has been an important research topic in cognitive science, mental health, and human-machine interaction. Previous works observed mobile device addiction by logging mobile devices activity. Although immersion has been linked as a significant predictor of video game addiction, investigation on addiction factors of mobile device with behavioral measurement has never been done before. In this research, we demonstrated the usage of eye tracking to observe effect of screen size on experience of immersion. We compared subjective judgment with eye movements analysis. Non-parametric analysis on immersion score shows that screen size affects experience of immersion (p<;0.05). Furthermore, our experimental results suggest that fixational eye movements may be used as an indicator for future investigation of mobile devices addiction. Our experimental results are also useful to develop a guideline as well as intervention strategy to deal with smartphone addiction.

Infections on the move: how transient phases of host movement influence disease spread

PubMed Central

Fenton, A.; Dell, A. I.

2017-01-01

Animal movement impacts the spread of human and wildlife diseases, and there is significant interest in understanding the role of migrations, biological invasions and other wildlife movements in spatial infection dynamics. However, the influence of processes acting on infections during transient phases of host movement is poorly understood. We propose a conceptual framework that explicitly considers infection dynamics during transient phases of host movement to better predict infection spread through spatial host networks. Accounting for host transient movement captures key processes that occur while hosts move between locations, which together determine the rate at which hosts spread infections through networks. We review theoretical and empirical studies of host movement and infection spread, highlighting the multiple factors that impact the infection status of hosts. We then outline characteristics of hosts, parasites and the environment that influence these dynamics. Recent technological advances provide disease ecologists unprecedented ability to track the fine-scale movement of organisms. These, in conjunction with experimental testing of the factors driving infection dynamics during host movement, can inform models of infection spread based on constituent biological processes. PMID:29263283

30 CFR 57.14218 - Movement of equipment on adjacent tracks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Movement of equipment on adjacent tracks. 57.14218 Section 57.14218 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... MINES Machinery and Equipment Safety Practices and Operational Procedures § 57.14218 Movement of...

30 CFR 56.14218 - Movement of equipment on adjacent tracks.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Movement of equipment on adjacent tracks. 56.14218 Section 56.14218 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... Machinery and Equipment Safety Practices and Operational Procedures § 56.14218 Movement of equipment on...

A model for combined targeting and tracking tasks in computer applications.

PubMed

Senanayake, Ransalu; Hoffmann, Errol R; Goonetilleke, Ravindra S

2013-11-01

Current models for targeted-tracking are discussed and shown to be inadequate as a means of understanding the combined task of tracking, as in the Drury's paradigm, and having a final target to be aimed at, as in the Fitts' paradigm. It is shown that the task has to be split into components that are, in general, performed sequentially and have a movement time component dependent on the difficulty of the individual component of the task. In some cases, the task time may be controlled by the Fitts' task difficulty, and in others, it may be dominated by the Drury's task difficulty. Based on an experiment carried out that captured movement time in combinations of visually controlled and ballistic movements, a model for movement time in targeted-tracking was developed.

Technical Report of Successful Deployment of Tandem Visual Tracking During Live Laparoscopic Cholecystectomy Between Novice and Expert Surgeon

PubMed Central

Baronia, Benedicto C

2016-01-01

With the recent advances in eye tracking technology, it is now possible to track surgeons’ eye movements while engaged in a surgical task or when surgical residents practice their surgical skills. Several studies have compared eye movements of surgical experts and novices and developed techniques to assess surgical skill on the basis of eye movement utilizing simulators and live surgery. None have evaluated simultaneous visual tracking between an expert and a novice during live surgery. Here, we describe a successful simultaneous deployment of visual tracking of an expert and a novice during live laparoscopic cholecystectomy. One expert surgeon and one chief surgical resident at an accredited surgical program in Lubbock, TX, USA performed a live laparoscopic cholecystectomy while simultaneously wearing the visual tracking devices. Their visual attitudes and movements were monitored via video recordings. The recordings were then analyzed for correlation between the expert and the novice. The visual attitudes and movements correlated approximately 85% between an expert surgeon and a chief surgical resident. The surgery was carried out uneventfully, and the data was abstracted with ease. We conclude that simultaneous deployment of visual tracking during live laparoscopic surgery is a possibility. More studies and subjects are needed to verify the success of our results and obtain data analysis. PMID:27774359

Tracking the Evolution of Smartphone Sensing for Monitoring Human Movement

PubMed Central

del Rosario, Michael B.; Redmond, Stephen J.; Lovell, Nigel H.

2015-01-01

Advances in mobile technology have led to the emergence of the “smartphone”, a new class of device with more advanced connectivity features that have quickly made it a constant presence in our lives. Smartphones are equipped with comparatively advanced computing capabilities, a global positioning system (GPS) receivers, and sensing capabilities (i.e., an inertial measurement unit (IMU) and more recently magnetometer and barometer) which can be found in wearable ambulatory monitors (WAMs). As a result, algorithms initially developed for WAMs that “count” steps (i.e., pedometers); gauge physical activity levels; indirectly estimate energy expenditure and monitor human movement can be utilised on the smartphone. These algorithms may enable clinicians to “close the loop” by prescribing timely interventions to improve or maintain wellbeing in populations who are at risk of falling or suffer from a chronic disease whose progression is linked to a reduction in movement and mobility. The ubiquitous nature of smartphone technology makes it the ideal platform from which human movement can be remotely monitored without the expense of purchasing, and inconvenience of using, a dedicated WAM. In this paper, an overview of the sensors that can be found in the smartphone are presented, followed by a summary of the developments in this field with an emphasis on the evolution of algorithms used to classify human movement. The limitations identified in the literature will be discussed, as well as suggestions about future research directions. PMID:26263998

What triggers catch-up saccades during visual tracking?

PubMed

de Brouwer, Sophie; Yuksel, Demet; Blohm, Gunnar; Missal, Marcus; Lefèvre, Philippe

2002-03-01

When tracking moving visual stimuli, primates orient their visual axis by combining two kinds of eye movements, smooth pursuit and saccades, that have very different dynamics. Yet, the mechanisms that govern the decision to switch from one type of eye movement to the other are still poorly understood, even though they could bring a significant contribution to the understanding of how the CNS combines different kinds of control strategies to achieve a common motor and sensory goal. In this study, we investigated the oculomotor responses to a large range of different combinations of position error and velocity error during visual tracking of moving stimuli in humans. We found that the oculomotor system uses a prediction of the time at which the eye trajectory will cross the target, defined as the "eye crossing time" (T(XE)). The eye crossing time, which depends on both position error and velocity error, is the criterion used to switch between smooth and saccadic pursuit, i.e., to trigger catch-up saccades. On average, for T(XE) between 40 and 180 ms, no saccade is triggered and target tracking remains purely smooth. Conversely, when T(XE) becomes smaller than 40 ms or larger than 180 ms, a saccade is triggered after a short latency (around 125 ms).

An integrated movement capture and control platform applied towards autonomous movements of surgical robots.

PubMed

Daluja, Sachin; Golenberg, Lavie; Cao, Alex; Pandya, Abhilash K; Auner, Gregory W; Klein, Michael D

2009-01-01

Robotic surgery has gradually gained acceptance due to its numerous advantages such as tremor filtration, increased dexterity and motion scaling. There remains, however, a significant scope for improvement, especially in the areas of surgeon-robot interface and autonomous procedures. Previous studies have attempted to identify factors affecting a surgeon's performance in a master-slave robotic system by tracking hand movements. These studies relied on conventional optical or magnetic tracking systems, making their use impracticable in the operating room. This study concentrated on building an intrinsic movement capture platform using microcontroller based hardware wired to a surgical robot. Software was developed to enable tracking and analysis of hand movements while surgical tasks were performed. Movement capture was applied towards automated movements of the robotic instruments. By emulating control signals, recorded surgical movements were replayed by the robot's end-effectors. Though this work uses a surgical robot as the platform, the ideas and concepts put forward are applicable to telerobotic systems in general.

Modeling and Identification of a Realistic Spiking Neural Network and Musculoskeletal Model of the Human Arm, and an Application to the Stretch Reflex.

PubMed

Sreenivasa, Manish; Ayusawa, Ko; Nakamura, Yoshihiko

2016-05-01

This study develops a multi-level neuromuscular model consisting of topological pools of spiking motor, sensory and interneurons controlling a bi-muscular model of the human arm. The spiking output of motor neuron pools were used to drive muscle actions and skeletal movement via neuromuscular junctions. Feedback information from muscle spindles were relayed via monosynaptic excitatory and disynaptic inhibitory connections, to simulate spinal afferent pathways. Subject-specific model parameters were identified from human experiments by using inverse dynamics computations and optimization methods. The identified neuromuscular model was used to simulate the biceps stretch reflex and the results were compared to an independent dataset. The proposed model was able to track the recorded data and produce dynamically consistent neural spiking patterns, muscle forces and movement kinematics under varying conditions of external forces and co-contraction levels. This additional layer of detail in neuromuscular models has important relevance to the research communities of rehabilitation and clinical movement analysis by providing a mathematical approach to studying neuromuscular pathology.

BORC Functions Upstream of Kinesins 1 and 3 to Coordinate Regional Movement of Lysosomes along Different Microtubule Tracks.

PubMed

Guardia, Carlos M; Farías, Ginny G; Jia, Rui; Pu, Jing; Bonifacino, Juan S

2016-11-15

The multiple functions of lysosomes are critically dependent on their ability to undergo bidirectional movement along microtubules between the center and the periphery of the cell. Centrifugal and centripetal movement of lysosomes is mediated by kinesin and dynein motors, respectively. We recently described a multi-subunit complex named BORC that recruits the small GTPase Arl8 to lysosomes to promote their kinesin-dependent movement toward the cell periphery. Here, we show that BORC and Arl8 function upstream of two structurally distinct kinesin types: kinesin-1 (KIF5B) and kinesin-3 (KIF1Bβ and KIF1A). Remarkably, KIF5B preferentially moves lysosomes on perinuclear tracks enriched in acetylated α-tubulin, whereas KIF1Bβ and KIF1A drive lysosome movement on more rectilinear, peripheral tracks enriched in tyrosinated α-tubulin. These findings establish BORC as a master regulator of lysosome positioning through coupling to different kinesins and microtubule tracks. Common regulation by BORC enables coordinate control of lysosome movement in different regions of the cell. Published by Elsevier Inc.

BORC Functions Upstream of Kinesins 1 and 3 to Coordinate Regional Movement of Lysosomes Along Different Microtubule Tracks

PubMed Central

Guardia, Carlos M.; Farías, Ginny G.; Jia, Rui; Pu, Jing; Bonifacino, Juan S.

2016-01-01

Summary The multiple functions of lysosomes are critically dependent on their ability to undergo bidirectional movement along microtubules between the center and the periphery of the cell. Centrifugal and centripetal movement of lysosomes is mediated by kinesin and dynein motors, respectively. We recently described a multisubunit complex named BORC that recruits the small GTPase Arl8 to lysosomes to promote their kinesin-dependent movement toward the cell periphery. Here we show that BORC and Arl8 function upstream of two structurally distinct kinesin types: kinesin-1 (KIF5B) and kinesin-3 (KIF1Bβ and KIF1A). Remarkably, KIF5B preferentially moves lysosomes on perinuclear tracks enriched in acetylated α-tubulin, whereas KIF1Bβ and KIF1A drive lysosome movement on more rectilinear, peripheral tracks enriched in tyrosinated α-tubulin. These findings establish BORC as a master regulator of lysosome positioning through coupling to different kinesins and microtubule tracks. Common regulation by BORC enables coordinate control of lysosome movement in different regions of the cell. PMID:27851960

Eye Movements During Everyday Behavior Predict Personality Traits

PubMed Central

Hoppe, Sabrina; Loetscher, Tobias; Morey, Stephanie A.; Bulling, Andreas

2018-01-01

Besides allowing us to perceive our surroundings, eye movements are also a window into our mind and a rich source of information on who we are, how we feel, and what we do. Here we show that eye movements during an everyday task predict aspects of our personality. We tracked eye movements of 42 participants while they ran an errand on a university campus and subsequently assessed their personality traits using well-established questionnaires. Using a state-of-the-art machine learning method and a rich set of features encoding different eye movement characteristics, we were able to reliably predict four of the Big Five personality traits (neuroticism, extraversion, agreeableness, conscientiousness) as well as perceptual curiosity only from eye movements. Further analysis revealed new relations between previously neglected eye movement characteristics and personality. Our findings demonstrate a considerable influence of personality on everyday eye movement control, thereby complementing earlier studies in laboratory settings. Improving automatic recognition and interpretation of human social signals is an important endeavor, enabling innovative design of human–computer systems capable of sensing spontaneous natural user behavior to facilitate efficient interaction and personalization. PMID:29713270

Online Learners’ Reading Ability Detection Based on Eye-Tracking Sensors

PubMed Central

Zhan, Zehui; Zhang, Lei; Mei, Hu; Fong, Patrick S. W.

2016-01-01

The detection of university online learners’ reading ability is generally problematic and time-consuming. Thus the eye-tracking sensors have been employed in this study, to record temporal and spatial human eye movements. Learners’ pupils, blinks, fixation, saccade, and regression are recognized as primary indicators for detecting reading abilities. A computational model is established according to the empirical eye-tracking data, and applying the multi-feature regularization machine learning mechanism based on a Low-rank Constraint. The model presents good generalization ability with an error of only 4.9% when randomly running 100 times. It has obvious advantages in saving time and improving precision, with only 20 min of testing required for prediction of an individual learner’s reading ability. PMID:27626418

Biases in rhythmic sensorimotor coordination: effects of modality and intentionality.

PubMed

Debats, Nienke B; Ridderikhoff, Arne; de Boer, Betteco J; Peper, C Lieke E

2013-08-01

Sensorimotor biases were examined for intentional (tracking task) and unintentional (distractor task) rhythmic coordination. The tracking task involved unimanual tracking of either an oscillating visual signal or the passive movements of the contralateral hand (proprioceptive signal). In both conditions the required coordination patterns (isodirectional and mirror-symmetric) were defined relative to the body midline and the hands were not visible. For proprioceptive tracking the two patterns did not differ in stability, whereas for visual tracking the isodirectional pattern was performed more stably than the mirror-symmetric pattern. However, when visual feedback about the unimanual hand movements was provided during visual tracking, the isodirectional pattern ceased to be dominant. Together these results indicated that the stability of the coordination patterns did not depend on the modality of the target signal per se, but on the combination of sensory signals that needed to be processed (unimodal vs. cross-modal). The distractor task entailed rhythmic unimanual movements during which a rhythmic visual or proprioceptive distractor signal had to be ignored. The observed biases were similar as for intentional coordination, suggesting that intentionality did not affect the underlying sensorimotor processes qualitatively. Intentional tracking was characterized by active sensory pursuit, through muscle activity in the passively moved arm (proprioceptive tracking task) and rhythmic eye movements (visual tracking task). Presumably this pursuit afforded predictive information serving the coordination process. Copyright © 2013 Elsevier B.V. All rights reserved.

49 CFR 236.204 - Track signaled for movements in both directions, requirements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Block Signal Systems Standards § 236.204 Track signaled for movements in both...

49 CFR 236.204 - Track signaled for movements in both directions, requirements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES Automatic Block Signal Systems Standards § 236.204 Track signaled for movements in both...

Horizontal movements of Atlantic blue marlin (Makaira nigricans) in the Gulf of Mexico

USGS Publications Warehouse

Kraus, R.T.; Wells, R.J.D.; Rooker, J.R.

2011-01-01

We examined movements of Atlantic blue marlin (Makaira nigricans) from the Gulf of Mexico based upon 42 pop-up archival transmitting (PAT) tags. Long deployments (including one 334-day track) revealed diverse movement patterns within the Gulf of Mexico. North-south seasonal changes in blue marlin distribution showed strong correspondence with established seasonal patterns of sea surface temperature and primary production. During the summer spawning season, blue marlin utilized outer shelf and shelf edge waters in the northern Gulf of Mexico, and longer duration tracks indicated overwintering habitats in the Bay of Campeche. Egress occurred throughout the year and was difficult to determine because some tracks ended in the Straits of Florida (n = 3) while other tracks recorded movement through it or the Yucatan Channel (n = 4). Our results indicate that Atlantic blue marlin have a more restricted geographic range of habitats than previously recognized and that the Gulf of Mexico provides spatially dynamic suitable habitat that is utilized year-round through seasonal movements. ?? 2011 Springer-Verlag.

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.

Tracking boundary movement and exterior shape modelling in lung EIT imaging.

PubMed

Biguri, A; Grychtol, B; Adler, A; Soleimani, M

2015-06-01

Electrical impedance tomography (EIT) has shown significant promise for lung imaging. One key challenge for EIT in this application is the movement of electrodes during breathing, which introduces artefacts in reconstructed images. Various approaches have been proposed to compensate for electrode movement, but no comparison of these approaches is available. This paper analyses boundary model mismatch and electrode movement in lung EIT. The aim is to evaluate the extent to which various algorithms tolerate movement, and to determine if a patient specific model is required for EIT lung imaging. Movement data are simulated from a CT-based model, and image analysis is performed using quantitative figures of merit. The electrode movement is modelled based on expected values of chest movement and an extended Jacobian method is proposed to make use of exterior boundary tracking. Results show that a dynamical boundary tracking is the most robust method against any movement, but is computationally more expensive. Simultaneous electrode movement and conductivity reconstruction algorithms show increased robustness compared to only conductivity reconstruction. The results of this comparative study can help develop a better understanding of the impact of shape model mismatch and electrode movement in lung EIT.

Gaze Allocation in a Dynamic Situation: Effects of Social Status and Speaking

ERIC Educational Resources Information Center

Foulsham, Tom; Cheng, Joey T.; Tracy, Jessica L.; Henrich, Joseph; Kingstone, Alan

2010-01-01

Human visual attention operates in a context that is complex, social and dynamic. To explore this, we recorded people taking part in a group decision-making task and then showed video clips of these situations to new participants while tracking their eye movements. Observers spent the majority of time looking at the people in the videos, and in…

The Face Perception System becomes Species-Specific at 3 Months: An Eye-Tracking Study

ERIC Educational Resources Information Center

Di Giorgio, Elisa; Meary, David; Pascalis, Olivier; Simion, Francesca

2013-01-01

The current study aimed at investigating own- vs. other-species preferences in 3-month-old infants. The infants' eye movements were recorded during a visual preference paradigm to assess whether they show a preference for own-species faces when contrasted with other-species faces. Human and monkey faces, equated for all low-level perceptual…

A multimodal dataset for authoring and editing multimedia content: The MAMEM project.

PubMed

Nikolopoulos, Spiros; Petrantonakis, Panagiotis C; Georgiadis, Kostas; Kalaganis, Fotis; Liaros, Georgios; Lazarou, Ioulietta; Adam, Katerina; Papazoglou-Chalikias, Anastasios; Chatzilari, Elisavet; Oikonomou, Vangelis P; Kumar, Chandan; Menges, Raphael; Staab, Steffen; Müller, Daniel; Sengupta, Korok; Bostantjopoulou, Sevasti; Katsarou, Zoe; Zeilig, Gabi; Plotnik, Meir; Gotlieb, Amihai; Kizoni, Racheli; Fountoukidou, Sofia; Ham, Jaap; Athanasiou, Dimitrios; Mariakaki, Agnes; Comanducci, Dario; Sabatini, Edoardo; Nistico, Walter; Plank, Markus; Kompatsiaris, Ioannis

2017-12-01

We present a dataset that combines multimodal biosignals and eye tracking information gathered under a human-computer interaction framework. The dataset was developed in the vein of the MAMEM project that aims to endow people with motor disabilities with the ability to edit and author multimedia content through mental commands and gaze activity. The dataset includes EEG, eye-tracking, and physiological (GSR and Heart rate) signals collected from 34 individuals (18 able-bodied and 16 motor-impaired). Data were collected during the interaction with specifically designed interface for web browsing and multimedia content manipulation and during imaginary movement tasks. The presented dataset will contribute towards the development and evaluation of modern human-computer interaction systems that would foster the integration of people with severe motor impairments back into society.

Tracking the Eye Movement of Four Years Old Children Learning Chinese Words

ERIC Educational Resources Information Center

Lin, Dan; Chen, Guangyao; Liu, Yingyi; Liu, Jiaxin; Pan, Jue; Mo, Lei

2018-01-01

Storybook reading is the major source of literacy exposure for beginning readers. The present study tracked 4-year-old Chinese children's eye movements while they were reading simulated storybook pages. Their eye-movement patterns were examined in relation to their word learning gains. The same reading list, consisting of 20 two-character Chinese…

Feasibility of real-time location systems in monitoring recovery after major abdominal surgery.

PubMed

Dorrell, Robert D; Vermillion, Sarah A; Clark, Clancy J

2017-12-01

Early mobilization after major abdominal surgery decreases postoperative complications and length of stay, and has become a key component of enhanced recovery pathways. However, objective measures of patient movement after surgery are limited. Real-time location systems (RTLS), typically used for asset tracking, provide a novel approach to monitoring in-hospital patient activity. The current study investigates the feasibility of using RTLS to objectively track postoperative patient mobilization. The real-time location system employs a meshed network of infrared and RFID sensors and detectors that sample device locations every 3 s resulting in over 1 million data points per day. RTLS tracking was evaluated systematically in three phases: (1) sensitivity and specificity of the tracking device using simulated patient scenarios, (2) retrospective passive movement analysis of patient-linked equipment, and (3) prospective observational analysis of a patient-attached tracking device. RTLS tracking detected a simulated movement out of a room with sensitivity of 91% and specificity 100%. Specificity decreased to 75% if time out of room was less than 3 min. All RTLS-tagged patient-linked equipment was identified for 18 patients, but measurable patient movement associated with equipment was detected for only 2 patients (11%) with 1-8 out-of-room walks per day. Ten patients were prospectively monitored using RTLS badges following major abdominal surgery. Patient movement was recorded using patient diaries, direct observation, and an accelerometer. Sensitivity and specificity of RTLS patient tracking were both 100% in detecting out-of-room ambulation and correlated well with direct observation and patient-reported ambulation. Real-time location systems are a novel technology capable of objectively and accurately monitoring patient movement and provide an innovative approach to promoting early mobilization after surgery.

A relationship between eye movement patterns and performance in a precognitive tracking task

NASA Technical Reports Server (NTRS)

Repperger, D. W.; Hartzell, E. J.

1977-01-01

Eye movements made by various subjects in the performance of a precognitive tracking task are studied. The tracking task persented by an antiaircraft artillery (AAA) simulator has an input forcing function represented by a deterministic aircraft fly-by. The performance of subjects is ranked by two metrics. Good, mediocre, and poor trackers are selected for analysis based on performance during the difficult segment of the tracking task and over replications. Using phase planes to characterize both the eye movement patterns and the displayed error signal, a simple metric is developed to study these patterns. Two characterizations of eye movement strategies are defined and quantified. Using these two types of eye strategies, two conclusions are obtained about good, mediocre, and poor trackers. First, the eye tracker who used a fixed strategy will consistently perform better. Secondly, the best fixed strategy is defined as a Crosshair Fixator.

Human activities recognition by head movement using partial recurrent neural network

NASA Astrophysics Data System (ADS)

Tan, Henry C. C.; Jia, Kui; De Silva, Liyanage C.

2003-06-01

Traditionally, human activities recognition has been achieved mainly by the statistical pattern recognition methods or the Hidden Markov Model (HMM). In this paper, we propose a novel use of the connectionist approach for the recognition of ten simple human activities: walking, sitting down, getting up, squatting down and standing up, in both lateral and frontal views, in an office environment. By means of tracking the head movement of the subjects over consecutive frames from a database of different color image sequences, and incorporating the Elman model of the partial recurrent neural network (RNN) that learns the sequential patterns of relative change of the head location in the images, the proposed system is able to robustly classify all the ten activities performed by unseen subjects from both sexes, of different race and physique, with a recognition rate as high as 92.5%. This demonstrates the potential of employing partial RNN to recognize complex activities in the increasingly popular human-activities-based applications.

Bivariate Gaussian bridges: directional factorization of diffusion in Brownian bridge models.

PubMed

Kranstauber, Bart; Safi, Kamran; Bartumeus, Frederic

2014-01-01

In recent years high resolution animal tracking data has become the standard in movement ecology. The Brownian Bridge Movement Model (BBMM) is a widely adopted approach to describe animal space use from such high resolution tracks. One of the underlying assumptions of the BBMM is isotropic diffusive motion between consecutive locations, i.e. invariant with respect to the direction. Here we propose to relax this often unrealistic assumption by separating the Brownian motion variance into two directional components, one parallel and one orthogonal to the direction of the motion. Our new model, the Bivariate Gaussian bridge (BGB), tracks movement heterogeneity across time. Using the BGB and identifying directed and non-directed movement within a trajectory resulted in more accurate utilisation distributions compared to dynamic Brownian bridges, especially for trajectories with a non-isotropic diffusion, such as directed movement or Lévy like movements. We evaluated our model with simulated trajectories and observed tracks, demonstrating that the improvement of our model scales with the directional correlation of a correlated random walk. We find that many of the animal trajectories do not adhere to the assumptions of the BBMM. The proposed model improves accuracy when describing the space use both in simulated correlated random walks as well as observed animal tracks. Our novel approach is implemented and available within the "move" package for R.

Interactive Sonification of Spontaneous Movement of Children—Cross-Modal Mapping and the Perception of Body Movement Qualities through Sound

PubMed Central

Frid, Emma; Bresin, Roberto; Alborno, Paolo; Elblaus, Ludvig

2016-01-01

In this paper we present three studies focusing on the effect of different sound models in interactive sonification of bodily movement. We hypothesized that a sound model characterized by continuous smooth sounds would be associated with other movement characteristics than a model characterized by abrupt variation in amplitude and that these associations could be reflected in spontaneous movement characteristics. Three subsequent studies were conducted to investigate the relationship between properties of bodily movement and sound: (1) a motion capture experiment involving interactive sonification of a group of children spontaneously moving in a room, (2) an experiment involving perceptual ratings of sonified movement data and (3) an experiment involving matching between sonified movements and their visualizations in the form of abstract drawings. In (1) we used a system constituting of 17 IR cameras tracking passive reflective markers. The head positions in the horizontal plane of 3–4 children were simultaneously tracked and sonified, producing 3–4 sound sources spatially displayed through an 8-channel loudspeaker system. We analyzed children's spontaneous movement in terms of energy-, smoothness- and directness-index. Despite large inter-participant variability and group-specific effects caused by interaction among children when engaging in the spontaneous movement task, we found a small but significant effect of sound model. Results from (2) indicate that different sound models can be rated differently on a set of motion-related perceptual scales (e.g., expressivity and fluidity). Also, results imply that audio-only stimuli can evoke stronger perceived properties of movement (e.g., energetic, impulsive) than stimuli involving both audio and video representations. Findings in (3) suggest that sounds portraying bodily movement can be represented using abstract drawings in a meaningful way. We argue that the results from these studies support the existence of a cross-modal mapping of body motion qualities from bodily movement to sounds. Sound can be translated and understood from bodily motion, conveyed through sound visualizations in the shape of drawings and translated back from sound visualizations to audio. The work underlines the potential of using interactive sonification to communicate high-level features of human movement data. PMID:27891074

Interactive Sonification of Spontaneous Movement of Children-Cross-Modal Mapping and the Perception of Body Movement Qualities through Sound.

PubMed

Frid, Emma; Bresin, Roberto; Alborno, Paolo; Elblaus, Ludvig

2016-01-01

In this paper we present three studies focusing on the effect of different sound models in interactive sonification of bodily movement. We hypothesized that a sound model characterized by continuous smooth sounds would be associated with other movement characteristics than a model characterized by abrupt variation in amplitude and that these associations could be reflected in spontaneous movement characteristics. Three subsequent studies were conducted to investigate the relationship between properties of bodily movement and sound: (1) a motion capture experiment involving interactive sonification of a group of children spontaneously moving in a room, (2) an experiment involving perceptual ratings of sonified movement data and (3) an experiment involving matching between sonified movements and their visualizations in the form of abstract drawings. In (1) we used a system constituting of 17 IR cameras tracking passive reflective markers. The head positions in the horizontal plane of 3-4 children were simultaneously tracked and sonified, producing 3-4 sound sources spatially displayed through an 8-channel loudspeaker system. We analyzed children's spontaneous movement in terms of energy-, smoothness- and directness-index. Despite large inter-participant variability and group-specific effects caused by interaction among children when engaging in the spontaneous movement task, we found a small but significant effect of sound model. Results from (2) indicate that different sound models can be rated differently on a set of motion-related perceptual scales (e.g., expressivity and fluidity). Also, results imply that audio-only stimuli can evoke stronger perceived properties of movement (e.g., energetic, impulsive) than stimuli involving both audio and video representations. Findings in (3) suggest that sounds portraying bodily movement can be represented using abstract drawings in a meaningful way. We argue that the results from these studies support the existence of a cross-modal mapping of body motion qualities from bodily movement to sounds. Sound can be translated and understood from bodily motion, conveyed through sound visualizations in the shape of drawings and translated back from sound visualizations to audio. The work underlines the potential of using interactive sonification to communicate high-level features of human movement data.

Objective measurement of head movement differences in children with and without autism spectrum disorder.

PubMed

Martin, Katherine B; Hammal, Zakia; Ren, Gang; Cohn, Jeffrey F; Cassell, Justine; Ogihara, Mitsunori; Britton, Jennifer C; Gutierrez, Anibal; Messinger, Daniel S

2018-01-01

Deficits in motor movement in children with autism spectrum disorder (ASD) have typically been characterized qualitatively by human observers. Although clinicians have noted the importance of atypical head positioning (e.g. social peering and repetitive head banging) when diagnosing children with ASD, a quantitative understanding of head movement in ASD is lacking. Here, we conduct a quantitative comparison of head movement dynamics in children with and without ASD using automated, person-independent computer-vision based head tracking (Zface). Because children with ASD often exhibit preferential attention to nonsocial versus social stimuli, we investigated whether children with and without ASD differed in their head movement dynamics depending on stimulus sociality. The current study examined differences in head movement dynamics in children with ( n  = 21) and without ASD ( n  = 21). Children were video-recorded while watching a 16-min video of social and nonsocial stimuli. Three dimensions of rigid head movement-pitch (head nods), yaw (head turns), and roll (lateral head inclinations)-were tracked using Zface. The root mean square of pitch, yaw, and roll was calculated to index the magnitude of head angular displacement (quantity of head movement) and angular velocity (speed). Compared with children without ASD, children with ASD exhibited greater yaw displacement, indicating greater head turning, and greater velocity of yaw and roll, indicating faster head turning and inclination. Follow-up analyses indicated that differences in head movement dynamics were specific to the social rather than the nonsocial stimulus condition. Head movement dynamics (displacement and velocity) were greater in children with ASD than in children without ASD, providing a quantitative foundation for previous clinical reports. Head movement differences were evident in lateral (yaw and roll) but not vertical (pitch) movement and were specific to a social rather than nonsocial condition. When presented with social stimuli, children with ASD had higher levels of head movement and moved their heads more quickly than children without ASD. Children with ASD may use head movement to modulate their perception of social scenes.

Fecal indicator organism modeling and microbial source tracking in environmental waters: Chapter 3.4.6

USGS Publications Warehouse

Nevers, Meredith; Byappanahalli, Muruleedhara; Phanikumar, Mantha S.; Whitman, Richard L.

2016-01-01

Mathematical models have been widely applied to surface waters to estimate rates of settling, resuspension, flow, dispersion, and advection in order to calculate movement of particles that influence water quality. Of particular interest are the movement, survival, and persistence of microbial pathogens or their surrogates, which may contaminate recreational water, drinking water, or shellfish. Most models devoted to microbial water quality have been focused on fecal indicator organisms (FIO), which act as a surrogate for pathogens and viruses. Process-based modeling and statistical modeling have been used to track contamination events to source and to predict future events. The use of these two types of models require different levels of expertise and input; process-based models rely on theoretical physical constructs to explain present conditions and biological distribution while data-based, statistical models use extant paired data to do the same. The selection of the appropriate model and interpretation of results is critical to proper use of these tools in microbial source tracking. Integration of the modeling approaches could provide insight for tracking and predicting contamination events in real time. A review of modeling efforts reveals that process-based modeling has great promise for microbial source tracking efforts; further, combining the understanding of physical processes influencing FIO contamination developed with process-based models and molecular characterization of the population by gene-based (i.e., biological) or chemical markers may be an effective approach for locating sources and remediating contamination in order to protect human health better.

A novel in vivo method for lung segment movement tracking

NASA Astrophysics Data System (ADS)

Leira, H. O.; Tangen, G. A.; Hofstad, E. F.; Langø, T.; Amundsen, T.

2012-02-01

Knowledge about lung movement in health and disease is sparse. Current evaluation methods, such as CT, MRI and external view have significant limitations. To study respiratory movement for image guided tumour diagnostics and respiratory physiology, we needed a method that overcomes these limitations. We fitted balloon catheters with electromagnetic sensors, and placed them in lung lobes of ventilated pigs. The sensors sensed their position at 40 Hz in an electromagnetic tracking field with a precision of ∼0.5 mm. The method was evaluated by recording sensor movement in different body positions and at different tidal volumes. No ‘gold standard’ exists for lung segment tracking, so our results were compared to ‘common knowledge’. The sensors were easily placed, showed no clinically relevant position drift and yielded sub-millimetre accuracy. Our measurements fit ‘common knowledge’, as increased ventilation volume increased respiratory movement, and the right lung moved significantly less in the right than the left lateral position. The novel method for tracking lung segment movements during respiration was easy to implement and yielded high spatial and temporal resolution, and the equipment parts are reusable. It is easy to implement as a research tool for lung physiology, navigated bronchoscopy and radiation therapy.

Catch-up saccades in head-unrestrained conditions reveal that saccade amplitude is corrected using an internal model of target movement

PubMed Central

Daye, Pierre M.; Blohm, Gunnar; Lefèvre, Phillippe

2014-01-01

This study analyzes how human participants combine saccadic and pursuit gaze movements when they track an oscillating target moving along a randomly oriented straight line with the head free to move. We found that to track the moving target appropriately, participants triggered more saccades with increasing target oscillation frequency to compensate for imperfect tracking gains. Our sinusoidal paradigm allowed us to show that saccade amplitude was better correlated with internal estimates of position and velocity error at saccade onset than with those parameters 100 ms before saccade onset as head-restrained studies have shown. An analysis of saccadic onset time revealed that most of the saccades were triggered when the target was accelerating. Finally, we found that most saccades were triggered when small position errors were combined with large velocity errors at saccade onset. This could explain why saccade amplitude was better correlated with velocity error than with position error. Therefore, our results indicate that the triggering mechanism of head-unrestrained catch-up saccades combines position and velocity error at saccade onset to program and correct saccade amplitude rather than using sensory information 100 ms before saccade onset. PMID:24424378

The effect of human image in B2C website design: an eye-tracking study

NASA Astrophysics Data System (ADS)

Wang, Qiuzhen; Yang, Yi; Wang, Qi; Ma, Qingguo

2014-09-01

On B2C shopping websites, effective visual designs can bring about consumers' positive emotional experience. From this perspective, this article developed a research model to explore the impact of human image as a visual element on consumers' online shopping emotions and subsequent attitudes towards websites. This study conducted an eye-tracking experiment to collect both eye movement data and questionnaire data to test the research model. Questionnaire data analysis showed that product pictures combined with human image induced positive emotions among participants, thus promoting their attitudes towards online shopping websites. Specifically, product pictures with human image first produced higher levels of image appeal and perceived social presence, thus stimulating higher levels of enjoyment and subsequent positive attitudes towards the websites. Moreover, a moderating effect of product type was demonstrated on the relationship between the presence of human image and the level of image appeal. Specifically, human image significantly increased the level of image appeal when integrated in entertainment product pictures while this relationship was not significant in terms of utilitarian products. Eye-tracking data analysis further supported these results and provided plausible explanations. The presence of human image significantly increased the pupil size of participants regardless of product types. For entertainment products, participants paid more attention to product pictures integrated with human image whereas for utilitarian products more attention was paid to functional information of products than to product pictures no matter whether or not integrated with human image.

Influence of social presence on eye movements in visual search tasks.

PubMed

Liu, Na; Yu, Ruifeng

2017-12-01

This study employed an eye-tracking technique to investigate the influence of social presence on eye movements in visual search tasks. A total of 20 male subjects performed visual search tasks in a 2 (target presence: present vs. absent) × 2 (task complexity: complex vs. simple) × 2 (social presence: alone vs. a human audience) within-subject experiment. Results indicated that the presence of an audience could evoke a social facilitation effect on response time in visual search tasks. Compared with working alone, the participants made fewer and shorter fixations, larger saccades and shorter scan path in simple search tasks and more and longer fixations, smaller saccades and longer scan path in complex search tasks when working with an audience. The saccade velocity and pupil diameter in the audience-present condition were larger than those in the working-alone condition. No significant change in target fixation number was observed between two social presence conditions. Practitioner Summary: This study employed an eye-tracking technique to examine the influence of social presence on eye movements in visual search tasks. Results clarified the variation mechanism and characteristics of oculomotor scanning induced by social presence in visual search.

Cue-dependent memory-based smooth-pursuit in normal human subjects: importance of extra-retinal mechanisms for initial pursuit.

PubMed

Ito, Norie; Barnes, Graham R; Fukushima, Junko; Fukushima, Kikuro; Warabi, Tateo

2013-08-01

Using a cue-dependent memory-based smooth-pursuit task previously applied to monkeys, we examined the effects of visual motion-memory on smooth-pursuit eye movements in normal human subjects and compared the results with those of the trained monkeys. These results were also compared with those during simple ramp-pursuit that did not require visual motion-memory. During memory-based pursuit, all subjects exhibited virtually no errors in either pursuit-direction or go/no-go selection. Tracking eye movements of humans and monkeys were similar in the two tasks, but tracking eye movements were different between the two tasks; latencies of the pursuit and corrective saccades were prolonged, initial pursuit eye velocity and acceleration were lower, peak velocities were lower, and time to reach peak velocities lengthened during memory-based pursuit. These characteristics were similar to anticipatory pursuit initiated by extra-retinal components during the initial extinction task of Barnes and Collins (J Neurophysiol 100:1135-1146, 2008b). We suggest that the differences between the two tasks reflect differences between the contribution of extra-retinal and retinal components. This interpretation is supported by two further studies: (1) during popping out of the correct spot to enhance retinal image-motion inputs during memory-based pursuit, pursuit eye velocities approached those during simple ramp-pursuit, and (2) during initial blanking of spot motion during memory-based pursuit, pursuit components appeared in the correct direction. Our results showed the importance of extra-retinal mechanisms for initial pursuit during memory-based pursuit, which include priming effects and extra-retinal drive components. Comparison with monkey studies on neuronal responses and model analysis suggested possible pathways for the extra-retinal mechanisms.

Design considerations for a real-time ocular counterroll instrument

NASA Technical Reports Server (NTRS)

Hatamian, M.; Anderson, D. J.

1983-01-01

A real-time algorithm for measuring three-dimensional movement of the human eye, especially torsional movement, is presented. As its input, the system uses images of the eyeball taken at video rate. The amount of horizontal and vertical movement is extracted using a pupil tracking technique. The torsional movement is then measured by computing the discrete cross-correlation function between the circular samples of successive images of the iris patterns and searching for the position of the peak of the function. A local least square interpolation around the peak of the cross-correlation function is used to produce nearly unbiased estimates of torsion angle with accuracy of about 3-4 arcmin. Accuracies of better than 0.03 deg are achievable in torsional measurement with SNR higher than 36 dB. Horizontal and vertical rotations of up to + or - 13 deg can occur simultaneously with torsion without introducing any appreciable error in the counterrolling measurement process.

Influence of salinomycin treatment on division and movement of individual cancer cells cultured in normoxia or hypoxia evaluated with time-lapse digital holographic microscopy

PubMed Central

Kamlund, Sofia; Strand, Daniel; Janicke, Birgit; Alm, Kersti; Oredsson, Stina

2017-01-01

ABSTRACT Most studies on new cancer drugs are based on population-derived data, where the absence of response of a small population may pass unnoticed. Thus, individual longitudinal tracking of cells is important for the future development of efficient cancer treatments. We have used digital holographic microscopy to track individual JIMT-1 human breast cancer cells and L929 mouse fibroblast cultivated in normoxia or hypoxia. In addition, JIMT-1 cells were treated with salinomycin, a cancer stem cell targeting compound. Three-day time-lapse movies were captured and individual cells were analysed with respect to cell division (cell cycle length) and cell movement. Comparing population-doubling time derived from population-based growth curves and individual cell cycle time data from time-lapse movies show that the former hide a sub-population of dividing cells. Salinomycin treatment increased the motility of cells, however, this motility did not result in an increased distant migration i.e. the cells increased their local movement. MCF-7 breast cancer cells showed similar motility behaviour as salinomycin-treated JIMT-1 cells. We suggest that combining features, such as motility and migration, can be used to distinguish cancer cells with mesenchymal (JIMT-1) and epithelial (MCF-7) features. The data clearly emphasize the importance of longitudinal cell tracking to understand the biology of individual cells under different conditions. PMID:28933990

Real-time subpixel-accuracy tracking of single mitochondria in neurons reveals heterogeneous mitochondrial motion.

PubMed

Alsina, Adolfo; Lai, Wu Ming; Wong, Wai Kin; Qin, Xianan; Zhang, Min; Park, Hyokeun

2017-11-04

Mitochondria are essential for cellular survival and function. In neurons, mitochondria are transported to various subcellular regions as needed. Thus, defects in the axonal transport of mitochondria are related to the pathogenesis of neurodegenerative diseases, and the movement of mitochondria has been the subject of intense research. However, the inability to accurately track mitochondria with subpixel accuracy has hindered this research. Here, we report an automated method for tracking mitochondria based on the center of fluorescence. This tracking method, which is accurate to approximately one-tenth of a pixel, uses the centroid of an individual mitochondrion and provides information regarding the distance traveled between consecutive imaging frames, instantaneous speed, net distance traveled, and average speed. Importantly, this new tracking method enables researchers to observe both directed motion and undirected movement (i.e., in which the mitochondrion moves randomly within a small region, following a sub-diffusive motion). This method significantly improves our ability to analyze the movement of mitochondria and sheds light on the dynamic features of mitochondrial movement. Copyright © 2017 Elsevier Inc. All rights reserved.

Ultrasound assessment of fascial connectivity in the lower limb during maximal cervical flexion: technical aspects and practical application of automatic tracking.

PubMed

Cruz-Montecinos, Carlos; Cerda, Mauricio; Sanzana-Cuche, Rodolfo; Martín-Martín, Jaime; Cuesta-Vargas, Antonio

2016-01-01

The fascia provides and transmits forces for connective tissues, thereby regulating human posture and movement. One way to assess the myofascial interaction is a fascia ultrasound recording. Ultrasound can follow fascial displacement either manually or automatically through two-dimensional (2D) method. One possible method is the iterated Lucas-Kanade Pyramid (LKP) algorithm, which is based on automatic pixel tracking during passive movements in 2D fascial displacement assessments. Until now, the accumulated error over time has not been considered, even though it could be crucial for detecting fascial displacement in low amplitude movements. The aim of this study was to assess displacement of the medial gastrocnemius fascia during cervical spine flexion in a kyphotic posture with the knees extended and ankles at 90°. The ultrasound transducer was placed on the extreme dominant belly of the medial gastrocnemius. Displacement was calculated from nine automatically selected tracking points. To determine cervical flexion, an established 2D marker protocol was implemented. Offline pressure sensors were used to synchronize the 2D kinematic data from cervical flexion and deep fascia displacement of the medial gastrocnemius. Fifteen participants performed the cervical flexion task. The basal tracking error was 0.0211 mm. In 66 % of the subjects, a proximal fascial tissue displacement of the fascia above the basal error (0.076 mm ± 0.006 mm) was measured. Fascia displacement onset during cervical spine flexion was detected over 70 % of the cycle; however, only when detected for more than 80 % of the cycle was displacement considered statistically significant as compared to the first 10 % of the cycle (ANOVA, p < 0.05). By using an automated tracking method, the present analyses suggest statistically significant displacement of deep fascia. Further studies are needed to corroborate and fully understand the mechanisms associated with these results.

UltraTrack: Software for semi-automated tracking of muscle fascicles in sequences of B-mode ultrasound images.

PubMed

Farris, Dominic James; Lichtwark, Glen A

2016-05-01

Dynamic measurements of human muscle fascicle length from sequences of B-mode ultrasound images have become increasingly prevalent in biomedical research. Manual digitisation of these images is time consuming and algorithms for automating the process have been developed. Here we present a freely available software implementation of a previously validated algorithm for semi-automated tracking of muscle fascicle length in dynamic ultrasound image recordings, "UltraTrack". UltraTrack implements an affine extension to an optic flow algorithm to track movement of the muscle fascicle end-points throughout dynamically recorded sequences of images. The underlying algorithm has been previously described and its reliability tested, but here we present the software implementation with features for: tracking multiple fascicles in multiple muscles simultaneously; correcting temporal drift in measurements; manually adjusting tracking results; saving and re-loading of tracking results and loading a range of file formats. Two example runs of the software are presented detailing the tracking of fascicles from several lower limb muscles during a squatting and walking activity. We have presented a software implementation of a validated fascicle-tracking algorithm and made the source code and standalone versions freely available for download. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Tracking stem cells in tissue-engineered organs using magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Hachani, Roxanne; Lowdell, Mark; Birchall, Martin; Thanh, NguyêN. Thi Kim

2013-11-01

The use of human stem cells (SCs) in tissue engineering holds promise in revolutionising the treatment of numerous diseases. There is a pressing need to comprehend the distribution, movement and role of SCs once implanted onto scaffolds. Nanotechnology has provided a platform to investigate this through the development of inorganic magnetic nanoparticles (MNPs). MNPs can be used to label and track SCs by magnetic resonance imaging (MRI) since this clinically available imaging modality has high spatial resolution. In this review, we highlight recent applications of iron oxide and gadolinium based MNPs in SC labelling and MRI; and offer novel considerations for their future development.

Security Applications Of Computer Motion Detection

NASA Astrophysics Data System (ADS)

Bernat, Andrew P.; Nelan, Joseph; Riter, Stephen; Frankel, Harry

1987-05-01

An important area of application of computer vision is the detection of human motion in security systems. This paper describes the development of a computer vision system which can detect and track human movement across the international border between the United States and Mexico. Because of the wide range of environmental conditions, this application represents a stringent test of computer vision algorithms for motion detection and object identification. The desired output of this vision system is accurate, real-time locations for individual aliens and accurate statistical data as to the frequency of illegal border crossings. Because most detection and tracking routines assume rigid body motion, which is not characteristic of humans, new algorithms capable of reliable operation in our application are required. Furthermore, most current detection and tracking algorithms assume a uniform background against which motion is viewed - the urban environment along the US-Mexican border is anything but uniform. The system works in three stages: motion detection, object tracking and object identi-fication. We have implemented motion detection using simple frame differencing, maximum likelihood estimation, mean and median tests and are evaluating them for accuracy and computational efficiency. Due to the complex nature of the urban environment (background and foreground objects consisting of buildings, vegetation, vehicles, wind-blown debris, animals, etc.), motion detection alone is not sufficiently accurate. Object tracking and identification are handled by an expert system which takes shape, location and trajectory information as input and determines if the moving object is indeed representative of an illegal border crossing.

Developing and Integrating Advanced Movement Features Improves Automated Classification of Ciliate Species

PubMed Central

Soleymani, Ali; Pennekamp, Frank; Petchey, Owen L.; Weibel, Robert

2015-01-01

Recent advances in tracking technologies such as GPS or video tracking systems describe the movement paths of individuals in unprecedented details and are increasingly used in different fields, including ecology. However, extracting information from raw movement data requires advanced analysis techniques, for instance to infer behaviors expressed during a certain period of the recorded trajectory, or gender or species identity in case data is obtained from remote tracking. In this paper, we address how different movement features affect the ability to automatically classify the species identity, using a dataset of unicellular microbes (i.e., ciliates). Previously, morphological attributes and simple movement metrics, such as speed, were used for classifying ciliate species. Here, we demonstrate that adding advanced movement features, in particular such based on discrete wavelet transform, to morphological features can improve classification. These results may have practical applications in automated monitoring of waste water facilities as well as environmental monitoring of aquatic systems. PMID:26680591

Speech Analysis Based On Image Information from Lip Movement

NASA Astrophysics Data System (ADS)

Talha, Kamil S.; Wan, Khairunizam; Za'ba, S. K.; Mohamad Razlan, Zuradzman; B, Shahriman A.

2013-12-01

Deaf and hard of hearing people often have problems being able to understand and lip read other people. Usually deaf and hard of hearing people feel left out of conversation and sometimes they are actually ignored by other people. There are a variety of ways hearing-impaired person can communicate and gain accsss to the information. Communication support includes both technical and human aids. Human aids include interpreters, lip-readers and note-takers. Interpreters translate the Sign Language and must therefore be qualified. In this paper, vision system is used to track movements of the lip. In the experiment, the proposed system succesfully can differentiate 11 type of phonemes and then classified it to the respective viseme group. By using the proposed system the hearing-impaired persons could practise pronaunciations by themselve without support from the instructor.

Choice of tracks, microtubules and/or actin filaments for chloroplast photo-movement is differentially controlled by phytochrome and a blue light receptor.

PubMed

Sato, Y; Wada, M; Kadota, A

2001-01-01

Light induced chloroplast movement has been studied as a model system for photoreception and actin microfilament (MF)-based intracellular motilities in plants. Chloroplast photo-accumulation and -avoidance movement is mediated by phytochrome as well as blue light (BL) receptor in the moss Physcomitrella patens. Here we report the discovery of an involvement of a microtubule (MT)-based system in addition to an MF-based system in photorelocation of chloroplasts in this moss. In the dark, MTs provided tracks for rapid movement of chloroplasts in a longitudinal direction and MFs contributed the tracks for slow movement in any direction. We found that phytochrome responses utilized only the MT-based system, while BL responses had an alternative way of moving, either along MTs or MFs. MT-based systems were mediated by both photoreceptors, but chloroplasts showed movements with different velocity and pattern between them. No apparent difference in the behavior of chloroplast movement between the accumulation and avoidance movement was detected in phytochrome responses or BL responses, except for the direction of the movement. The results presented here demonstrate that chloroplasts use both MTs and MFs for motility and that phytochrome and a BL receptor control directional photo-movement of chloroplasts through the differential regulation of these motile systems.

Identifying Anxiety Through Tracked Head Movements in a Virtual Classroom.

PubMed

Won, Andrea Stevenson; Perone, Brian; Friend, Michelle; Bailenson, Jeremy N

2016-06-01

Virtual reality allows the controlled simulation of complex social settings, such as classrooms, and thus provides an opportunity to test a range of theories in the social sciences in a way that is both naturalistic and controlled. Importantly, virtual environments also allow the body movements of participants in the virtual world to be tracked and recorded. In the following article, we discuss how tracked head movements were correlated with participants' reports of anxiety in a simulation of a classroom. Participants who reported a high sense of awareness of and concern about the other virtual people in the room showed different patterns of head movement (more lateral head movement, indicating scanning behavior) from those who reported a low level of concern. We discuss the implications of this research for understanding nonverbal behavior associated with anxiety and for the design of online educational systems.

Magnetic eye tracking in mice

PubMed Central

Payne, Hannah L

2017-01-01

Eye movements provide insights about a wide range of brain functions, from sensorimotor integration to cognition; hence, the measurement of eye movements is an important tool in neuroscience research. We describe a method, based on magnetic sensing, for measuring eye movements in head-fixed and freely moving mice. A small magnet was surgically implanted on the eye, and changes in the magnet angle as the eye rotated were detected by a magnetic field sensor. Systematic testing demonstrated high resolution measurements of eye position of <0.1°. Magnetic eye tracking offers several advantages over the well-established eye coil and video-oculography methods. Most notably, it provides the first method for reliable, high-resolution measurement of eye movements in freely moving mice, revealing increased eye movements and altered binocular coordination compared to head-fixed mice. Overall, magnetic eye tracking provides a lightweight, inexpensive, easily implemented, and high-resolution method suitable for a wide range of applications. PMID:28872455

Perceptual control models of pursuit manual tracking demonstrate individual specificity and parameter consistency.

PubMed

Parker, Maximilian G; Tyson, Sarah F; Weightman, Andrew P; Abbott, Bruce; Emsley, Richard; Mansell, Warren

2017-11-01

Computational models that simulate individuals' movements in pursuit-tracking tasks have been used to elucidate mechanisms of human motor control. Whilst there is evidence that individuals demonstrate idiosyncratic control-tracking strategies, it remains unclear whether models can be sensitive to these idiosyncrasies. Perceptual control theory (PCT) provides a unique model architecture with an internally set reference value parameter, and can be optimized to fit an individual's tracking behavior. The current study investigated whether PCT models could show temporal stability and individual specificity over time. Twenty adults completed three blocks of 15 1-min, pursuit-tracking trials. Two blocks (training and post-training) were completed in one session and the third was completed after 1 week (follow-up). The target moved in a one-dimensional, pseudorandom pattern. PCT models were optimized to the training data using a least-mean-squares algorithm, and validated with data from post-training and follow-up. We found significant inter-individual variability (partial η 2 : .464-.697) and intra-individual consistency (Cronbach's α: .880-.976) in parameter estimates. Polynomial regression revealed that all model parameters, including the reference value parameter, contribute to simulation accuracy. Participants' tracking performances were significantly more accurately simulated by models developed from their own tracking data than by models developed from other participants' data. We conclude that PCT models can be optimized to simulate the performance of an individual and that the test-retest reliability of individual models is a necessary criterion for evaluating computational models of human performance.

Sex differences in a virtual water maze: an eye tracking and pupillometry study.

PubMed

Mueller, Sven C; Jackson, Carl P T; Skelton, Ron W

2008-11-21

Sex differences in human spatial navigation are well known. However, the exact strategies that males and females employ in order to navigate successfully around the environment are unclear. While some researchers propose that males prefer environment-centred (allocentric) and females prefer self-centred (egocentric) navigation, these findings have proved difficult to replicate. In the present study we examined eye movements and physiological measures of memory (pupillometry) in order to compare visual scanning of spatial orientation using a human virtual analogue of the Morris Water Maze task. Twelve women and twelve men (average age=24 years) were trained on a visible platform and had to locate an invisible platform over a series of trials. On all but the first trial, participants' eye movements were recorded for 3s and they were asked to orient themselves in the environment. While the behavioural data replicated previous findings of improved spatial performance for males relative to females, distinct sex differences in eye movements were found. Males tended to explore consistently more space early on while females demonstrated initially longer fixation durations and increases in pupil diameter usually associated with memory processing. The eye movement data provides novel insight into differences in navigational strategies between the sexes.

Joint action aesthetics.

PubMed

Vicary, Staci; Sperling, Matthias; von Zimmermann, Jorina; Richardson, Daniel C; Orgs, Guido

2017-01-01

Synchronized movement is a ubiquitous feature of dance and music performance. Much research into the evolutionary origins of these cultural practices has focused on why humans perform rather than watch or listen to dance and music. In this study, we show that movement synchrony among a group of performers predicts the aesthetic appreciation of live dance performances. We developed a choreography that continuously manipulated group synchronization using a defined movement vocabulary based on arm swinging, walking and running. The choreography was performed live to four audiences, as we continuously tracked the performers' movements, and the spectators' affective responses. We computed dynamic synchrony among performers using cross recurrence analysis of data from wrist accelerometers, and implicit measures of arousal from spectators' heart rates. Additionally, a subset of spectators provided continuous ratings of enjoyment and perceived synchrony using tablet computers. Granger causality analyses demonstrate predictive relationships between synchrony, enjoyment ratings and spectator arousal, if audiences form a collectively consistent positive or negative aesthetic evaluation. Controlling for the influence of overall movement acceleration and visual change, we show that dance communicates group coordination via coupled movement dynamics among a group of performers. Our findings are in line with an evolutionary function of dance-and perhaps all performing arts-in transmitting social signals between groups of people. Human movement is the common denominator of dance, music and theatre. Acknowledging the time-sensitive and immediate nature of the performer-spectator relationship, our study makes a significant step towards an aesthetics of joint actions in the performing arts.

Joint action aesthetics

PubMed Central

Vicary, Staci; Sperling, Matthias; von Zimmermann, Jorina; Richardson, Daniel C.

2017-01-01

Synchronized movement is a ubiquitous feature of dance and music performance. Much research into the evolutionary origins of these cultural practices has focused on why humans perform rather than watch or listen to dance and music. In this study, we show that movement synchrony among a group of performers predicts the aesthetic appreciation of live dance performances. We developed a choreography that continuously manipulated group synchronization using a defined movement vocabulary based on arm swinging, walking and running. The choreography was performed live to four audiences, as we continuously tracked the performers’ movements, and the spectators’ affective responses. We computed dynamic synchrony among performers using cross recurrence analysis of data from wrist accelerometers, and implicit measures of arousal from spectators’ heart rates. Additionally, a subset of spectators provided continuous ratings of enjoyment and perceived synchrony using tablet computers. Granger causality analyses demonstrate predictive relationships between synchrony, enjoyment ratings and spectator arousal, if audiences form a collectively consistent positive or negative aesthetic evaluation. Controlling for the influence of overall movement acceleration and visual change, we show that dance communicates group coordination via coupled movement dynamics among a group of performers. Our findings are in line with an evolutionary function of dance–and perhaps all performing arts–in transmitting social signals between groups of people. Human movement is the common denominator of dance, music and theatre. Acknowledging the time-sensitive and immediate nature of the performer-spectator relationship, our study makes a significant step towards an aesthetics of joint actions in the performing arts. PMID:28742849

Sensor and tracking data integration into a common operating picture

NASA Astrophysics Data System (ADS)

Bailey, Mark E.

2003-09-01

With rapid technological developments, a new innovative range of possibilities can be actualized in mainstreaming a network with checks and balances to provide sensor and tracking data integration/information to a wider Department of Defense (DoD) audience or group of agencies. As technologies are developed, methods to display the data are required. Multiple diverse tracking devices and sensors need to be displayed on a common operating picture. Sensors and tracking devices are used to monitor an area or object for movement or boundary penetration. Tracking devices in turn determine transit patterns of humans, animals and/or vehicles. In consortium these devices can have dual applications for military requirements and for other general purposes. The DoD Counterdrug Technology Development Program Office (CDTDPO) has designed a system to distribute sensor and tracking data to multiple users in separate agencies. This information can be displayed in whole or in part as to the specific needs of the user. It is with this purpose that the Data Distribution Network (DDN) was created to disseminate information to a collective group or to a select audience.

Summer movements, predation and habitat use of wolves in human modified boreal forests.

PubMed

Gurarie, Eliezer; Suutarinen, Johanna; Kojola, Ilpo; Ovaskainen, Otso

2011-04-01

Grey wolves (Canis lupus), formerly extirpated in Finland, have recolonized a boreal forest environment that has been significantly altered by humans, becoming a patchwork of managed forests and clearcuts crisscrossed by roads, power lines, and railways. Little is known about how the wolves utilize this impacted ecosystem, especially during the pup-rearing summer months. We tracked two wolves instrumented with GPS collars transmitting at 30-min intervals during two summers in eastern Finland, visiting all locations in the field, identifying prey items and classifying movement behaviors. We analyzed preference and avoidance of habitat types, linear elements and habitat edges, and tested the generality of our results against lower resolution summer movements of 23 other collared wolves. Wolves tended to show a strong preference for transitional woodlands (mostly harvested clearcuts) and mixed forests over coniferous forests and to use forest roads and low use linear elements to facilitate movement. The high density of primary roads in one wolf's territory led to more constrained use of the home territory compared to the wolf with fewer roads, suggesting avoidance of humans; however, there did not appear to be large differences on the hunting success or the success of pup rearing for the two packs. In total, 90 kills were identified, almost entirely moose (Alces alces) and reindeer (Rangifer tarandus sspp.) calves of which a large proportion were killed in transitional woodlands. Generally, wolves displayed a high level of adaptability, successfully exploiting direct and indirect human-derived modifications to the boreal forest environment.

Robotic gaming prototype for upper limb exercise: Effects of age and embodiment on user preferences and movement.

PubMed

Eizicovits, Danny; Edan, Yael; Tabak, Iris; Levy-Tzedek, Shelly

2018-01-01

Effective human-robot interactions in rehabilitation necessitates an understanding of how these should be tailored to the needs of the human. We report on a robotic system developed as a partner on a 3-D everyday task, using a gamified approach. To: (1) design and test a prototype system, to be ultimately used for upper-limb rehabilitation; (2) evaluate how age affects the response to such a robotic system; and (3) identify whether the robot's physical embodiment is an important aspect in motivating users to complete a set of repetitive tasks. 62 healthy participants, young (<30 yo) and old (>60 yo), played a 3D tic-tac-toe game against an embodied (a robotic arm) and a non-embodied (a computer-controlled lighting system) partner. To win, participants had to place three cups in sequence on a physical 3D grid. Cup picking-and-placing was chosen as a functional task that is often practiced in post-stroke rehabilitation. Movement of the participants was recorded using a Kinect camera. The timing of the participants' movement was primed by the response time of the system: participants moved slower when playing with the slower embodied system (p = 0.006). The majority of participants preferred the robot over the computer-controlled system. Slower response time of the robot compared to the computer-controlled one only affected the young group's motivation to continue playing. We demonstrated the feasibility of the system to encourage the performance of repetitive 3D functional movements, and track these movements. Young and old participants preferred to interact with the robot, compared with the non-embodied system. We contribute to the growing knowledge concerning personalized human-robot interactions by (1) demonstrating the priming of the human movement by the robotic movement - an important design feature, and (2) identifying response-speed as a design variable, the importance of which depends on the age of the user.

Environmental drivers of variability in the movement ecology of turkey vultures (Cathartes aura) in North and South America.

PubMed

Dodge, Somayeh; Bohrer, Gil; Bildstein, Keith; Davidson, Sarah C; Weinzierl, Rolf; Bechard, Marc J; Barber, David; Kays, Roland; Brandes, David; Han, Jiawei; Wikelski, Martin

2014-01-01

Variation is key to the adaptability of species and their ability to survive changes to the Earth's climate and habitats. Plasticity in movement strategies allows a species to better track spatial dynamics of habitat quality. We describe the mechanisms that shape the movement of a long-distance migrant bird (turkey vulture, Cathartes aura) across two continents using satellite tracking coupled with remote-sensing science. Using nearly 10 years of data from 24 satellite-tracked vultures in four distinct populations, we describe an enormous amount of variation in their movement patterns. We related vulture movement to environmental conditions and found important correlations explaining how far they need to move to find food (indexed by the Normalized Difference Vegetation Index) and how fast they can move based on the prevalence of thermals and temperature. We conclude that the extensive variability in the movement ecology of turkey vultures, facilitated by their energetically efficient thermal soaring, suggests that this species is likely to do well across periods of modest climate change. The large scale and sample sizes needed for such analysis in a widespread migrant emphasizes the need for integrated and collaborative efforts to obtain tracking data and for policies, tools and open datasets to encourage such collaborations and data sharing.

A Case History of Tracking Water Movement Through Fracture Systems in the Barnett Shale, March 10-11, 2011

EPA Pesticide Factsheets

Technical Presentation Session 6: Monitoring slides to presentation by Denbury on tracking water movement through fracture systems in the Barnett shale. This includes information on micro-seismic well evaluation, well plans, and a fracture map.

Monitoring Human Performance During Suited Operations: A Technology Feasibility Study Using EMU Gloves

NASA Technical Reports Server (NTRS)

Bekdash, Omar; Norcross, Jason; McFarland, Shane

2015-01-01

Mobility tracking of human subjects while conducting suited operations still remains focused on the external movement of the suit and little is known about the human movement within it. For this study, accelerometers and bend sensitive resistors were integrated into a custom carrier glove to quantify range of motion and dexterity from within the pressurized glove environment as a first stage feasibility study of sensor hardware, integration, and reporting capabilities. Sensors were also placed on the exterior of the pressurized glove to determine if it was possible to compare a glove joint angle to the anatomical joint angle of the subject during tasks. Quantifying human movement within the suit was feasible, with accelerometers clearly detecting movements in the wrist and reporting expected joint angles at maximum flexion or extension postures with repeatability of plus or minus 5 degrees between trials. Bend sensors placed on the proximal interphalangeal and distal interphalangeal joints performed less well. It was not possible to accurately determine the actual joint angle using these bend sensors, but these sensors could be used to determine when the joint was flexed to its maximum and provide a general range of mobility needed to complete a task. Further work includes additional testing with accelerometers and the possible inclusion of hardware such as magnetometers or gyroscopes to more precisely locate the joint in 3D space. We hope to eventually expand beyond the hand and glove and develop a more comprehensive suit sensor suite to characterize motion across more joints (knee, elbow, shoulder, etc.) and fully monitor the human body operating within the suit environment.

Tracking painted pebbles: Short-term rates of sediment movement on four Mojave Desert piedmont surfaces

NASA Astrophysics Data System (ADS)

Persico, Lyman P.; Nichols, Kyle K.; Bierman, Paul R.

2005-07-01

To quantify short-term sediment movement rates across Mojave Desert piedmonts, 1600 painted and numbered pebbles were laid out in paired, orthogonal, 20 m lines at 4 sites and resurveyed five times over 2 years and revisited 2 years later. Pebble lines cross shallow (5-15 cm), ephemeral channels and adjacent unconsolidated interfluves, the latter being the dominant landform at all sites. Two sites are located on surfaces that have been or are impacted by military training activities, including the use of tracked vehicles. The two other sites have not been disturbed by human impact. Three different processes transport pebbles. Episodic streamflow in ephemeral channels transports a few pebbles long distances (decimeters to meters) down gradient. Bioturbation moves many pebbles small distances (centimeters) in any direction, and vehicular disturbance transports pebbles varying distances (centimeters to meters) in any direction. Significant down-gradient sediment movement occurred dominantly in channels where flowing water was concentrated. Interfluves were stable surfaces where little transport occurred. Off-road vehicle use is coincident with accelerated pebble movement. Pebbles moved further and faster down gradient at the disturbed Iron Mountain and East Range Road sites (mean speeds of 0.18 and 0.34 m yr-1, respectively) than at the undisturbed Chemehuevi and Goldstone sites, (mean speeds of 0.17 and 0.02 m yr-1, respectively). Mean pebble movement is highly and negatively correlated with vegetation density. Short-term pebble movement rates are several times lower than long-term (103 to 104 year) rates, suggesting the importance of rare, extreme precipitation events for sediment transport such as those of fall and winter 2004.

Robot-Assisted Proprioceptive Training with Added Vibro-Tactile Feedback Enhances Somatosensory and Motor Performance.

PubMed

Cuppone, Anna Vera; Squeri, Valentina; Semprini, Marianna; Masia, Lorenzo; Konczak, Jürgen

2016-01-01

This study examined the trainability of the proprioceptive sense and explored the relationship between proprioception and motor learning. With vision blocked, human learners had to perform goal-directed wrist movements relying solely on proprioceptive/haptic cues to reach several haptically specified targets. One group received additional somatosensory movement error feedback in form of vibro-tactile cues applied to the skin of the forearm. We used a haptic robotic device for the wrist and implemented a 3-day training regimen that required learners to make spatially precise goal-directed wrist reaching movements without vision. We assessed whether training improved the acuity of the wrist joint position sense. In addition, we checked if sensory learning generalized to the motor domain and improved spatial precision of wrist tracking movements that were not trained. The main findings of the study are: First, proprioceptive acuity of the wrist joint position sense improved after training for the group that received the combined proprioceptive/haptic and vibro-tactile feedback (VTF). Second, training had no impact on the spatial accuracy of the untrained tracking task. However, learners who had received VTF significantly reduced their reliance on haptic guidance feedback when performing the untrained motor task. That is, concurrent VTF was highly salient movement feedback and obviated the need for haptic feedback. Third, VTF can be also provided by the limb not involved in the task. Learners who received VTF to the contralateral limb equally benefitted. In conclusion, somatosensory training can significantly enhance proprioceptive acuity within days when learning is coupled with vibro-tactile sensory cues that provide feedback about movement errors. The observable sensory improvements in proprioception facilitates motor learning and such learning may generalize to the sensorimotor control of the untrained motor tasks. The implications of these findings for neurorehabilitation are discussed.

Utility of optical facial feature and arm movement tracking systems to enable text communication in critically ill patients who cannot otherwise communicate.

PubMed

Muthuswamy, M B; Thomas, B N; Williams, D; Dingley, J

2014-09-01

Patients recovering from critical illness especially those with critical illness related neuropathy, myopathy, or burns to face, arms and hands are often unable to communicate by writing, speech (due to tracheostomy) or lip reading. This may frustrate both patient and staff. Two low cost movement tracking systems based around a laptop webcam and a laser/optical gaming system sensor were utilised as control inputs for on-screen text creation software and both were evaluated as communication tools in volunteers. Two methods were used to control an on-screen cursor to create short sentences via an on-screen keyboard: (i) webcam-based facial feature tracking, (ii) arm movement tracking by laser/camera gaming sensor and modified software. 16 volunteers with simulated tracheostomy and bandaged arms to simulate communication via gross movements of a burned limb, communicated 3 standard messages using each system (total 48 per system) in random sequence. Ten and 13 minor typographical errors occurred with each system respectively, however all messages were comprehensible. Speed of sentence formation ranged from 58 to 120s with the facial feature tracking system, and 60-160s with the arm movement tracking system. The average speed of sentence formation was 81s (range 58-120) and 104s (range 60-160) for facial feature and arm tracking systems respectively, (P<0.001, 2-tailed independent sample t-test). Both devices may be potentially useful communication aids in patients in general and burns critical care units who cannot communicate by conventional means, due to the nature of their injuries. Copyright © 2014 Elsevier Ltd and ISBI. All rights reserved.

Hybrid BCI approach to control an artificial tibio-femoral joint.

PubMed

Mercado, Luis; Rodriguez-Linan, Angel; Torres-Trevino, Luis M; Quiroz, G

2016-08-01

Brain-Computer Interfaces (BCIs) for disabled people should allow them to use their remaining functionalities as control possibilities. BCIs connect the brain with external devices to perform the volition or intent of movement, regardless if that individual is unable to perform the task due to body impairments. In this work we fuse electromyographic (EMG) with electroencephalographic (EEG) activity in a framework called "Hybrid-BCI" (hBCI) approach to control the movement of a simulated tibio-femoral joint. Two mathematical models of a tibio-femoral joint are used to emulate the kinematic and dynamic behavior of the knee. The interest is to reproduce different velocities of the human gait cycle. The EEG signals are used to classify the user intent, which are the velocity changes, meanwhile the superficial EMG signals are used to estimate the amplitude of such intent. A multi-level controller is used to solve the trajectory tracking problem involved. The lower level consists of an individual controller for each model, it solves the tracking of the desired trajectory even considering different velocities of the human gait cycle. The mid-level uses a combination of a logical operator and a finite state machine for the switching between models. Finally, the highest level consists in a support vector machine to classify the desired activity.

Integrating optical finger motion tracking with surface touch events.

PubMed

MacRitchie, Jennifer; McPherson, Andrew P

2015-01-01

This paper presents a method of integrating two contrasting sensor systems for studying human interaction with a mechanical system, using piano performance as the case study. Piano technique requires both precise small-scale motion of fingers on the key surfaces and planned large-scale movement of the hands and arms. Where studies of performance often focus on one of these scales in isolation, this paper investigates the relationship between them. Two sensor systems were installed on an acoustic grand piano: a monocular high-speed camera tracking the position of painted markers on the hands, and capacitive touch sensors attach to the key surfaces which measure the location of finger-key contacts. This paper highlights a method of fusing the data from these systems, including temporal and spatial alignment, segmentation into notes and automatic fingering annotation. Three case studies demonstrate the utility of the multi-sensor data: analysis of finger flexion or extension based on touch and camera marker location, timing analysis of finger-key contact preceding and following key presses, and characterization of individual finger movements in the transitions between successive key presses. Piano performance is the focus of this paper, but the sensor method could equally apply to other fine motor control scenarios, with applications to human-computer interaction.

Integrating optical finger motion tracking with surface touch events

PubMed Central

MacRitchie, Jennifer; McPherson, Andrew P.

2015-01-01

This paper presents a method of integrating two contrasting sensor systems for studying human interaction with a mechanical system, using piano performance as the case study. Piano technique requires both precise small-scale motion of fingers on the key surfaces and planned large-scale movement of the hands and arms. Where studies of performance often focus on one of these scales in isolation, this paper investigates the relationship between them. Two sensor systems were installed on an acoustic grand piano: a monocular high-speed camera tracking the position of painted markers on the hands, and capacitive touch sensors attach to the key surfaces which measure the location of finger-key contacts. This paper highlights a method of fusing the data from these systems, including temporal and spatial alignment, segmentation into notes and automatic fingering annotation. Three case studies demonstrate the utility of the multi-sensor data: analysis of finger flexion or extension based on touch and camera marker location, timing analysis of finger-key contact preceding and following key presses, and characterization of individual finger movements in the transitions between successive key presses. Piano performance is the focus of this paper, but the sensor method could equally apply to other fine motor control scenarios, with applications to human-computer interaction. PMID:26082732

Eye Tracking of Occluded Self-Moved Targets: Role of Haptic Feedback and Hand-Target Dynamics.

PubMed

Danion, Frederic; Mathew, James; Flanagan, J Randall

2017-01-01

Previous studies on smooth pursuit eye movements have shown that humans can continue to track the position of their hand, or a target controlled by the hand, after it is occluded, thereby demonstrating that arm motor commands contribute to the prediction of target motion driving pursuit eye movements. Here, we investigated this predictive mechanism by manipulating both the complexity of the hand-target mapping and the provision of haptic feedback. Two hand-target mappings were used, either a rigid (simple) one in which hand and target motion matched perfectly or a nonrigid (complex) one in which the target behaved as a mass attached to the hand by means of a spring. Target animation was obtained by asking participants to oscillate a lightweight robotic device that provided (or not) haptic feedback consistent with the target dynamics. Results showed that as long as 7 s after target occlusion, smooth pursuit continued to be the main contributor to total eye displacement (∼60%). However, the accuracy of eye-tracking varied substantially across experimental conditions. In general, eye-tracking was less accurate under the nonrigid mapping, as reflected by higher positional and velocity errors. Interestingly, haptic feedback helped to reduce the detrimental effects of target occlusion when participants used the nonrigid mapping, but not when they used the rigid one. Overall, we conclude that the ability to maintain smooth pursuit in the absence of visual information can extend to complex hand-target mappings, but the provision of haptic feedback is critical for the maintenance of accurate eye-tracking performance.

Eye Tracking of Occluded Self-Moved Targets: Role of Haptic Feedback and Hand-Target Dynamics

PubMed Central

Mathew, James

2017-01-01

Abstract Previous studies on smooth pursuit eye movements have shown that humans can continue to track the position of their hand, or a target controlled by the hand, after it is occluded, thereby demonstrating that arm motor commands contribute to the prediction of target motion driving pursuit eye movements. Here, we investigated this predictive mechanism by manipulating both the complexity of the hand-target mapping and the provision of haptic feedback. Two hand-target mappings were used, either a rigid (simple) one in which hand and target motion matched perfectly or a nonrigid (complex) one in which the target behaved as a mass attached to the hand by means of a spring. Target animation was obtained by asking participants to oscillate a lightweight robotic device that provided (or not) haptic feedback consistent with the target dynamics. Results showed that as long as 7 s after target occlusion, smooth pursuit continued to be the main contributor to total eye displacement (∼60%). However, the accuracy of eye-tracking varied substantially across experimental conditions. In general, eye-tracking was less accurate under the nonrigid mapping, as reflected by higher positional and velocity errors. Interestingly, haptic feedback helped to reduce the detrimental effects of target occlusion when participants used the nonrigid mapping, but not when they used the rigid one. Overall, we conclude that the ability to maintain smooth pursuit in the absence of visual information can extend to complex hand-target mappings, but the provision of haptic feedback is critical for the maintenance of accurate eye-tracking performance. PMID:28680964

Eye Tracking Based Control System for Natural Human-Computer Interaction

PubMed Central

Lin, Shu-Fan

2017-01-01

Eye movement can be regarded as a pivotal real-time input medium for human-computer communication, which is especially important for people with physical disability. In order to improve the reliability, mobility, and usability of eye tracking technique in user-computer dialogue, a novel eye control system with integrating both mouse and keyboard functions is proposed in this paper. The proposed system focuses on providing a simple and convenient interactive mode by only using user's eye. The usage flow of the proposed system is designed to perfectly follow human natural habits. Additionally, a magnifier module is proposed to allow the accurate operation. In the experiment, two interactive tasks with different difficulty (searching article and browsing multimedia web) were done to compare the proposed eye control tool with an existing system. The Technology Acceptance Model (TAM) measures are used to evaluate the perceived effectiveness of our system. It is demonstrated that the proposed system is very effective with regard to usability and interface design. PMID:29403528

Eye Tracking Based Control System for Natural Human-Computer Interaction.

PubMed

Zhang, Xuebai; Liu, Xiaolong; Yuan, Shyan-Ming; Lin, Shu-Fan

2017-01-01

Eye movement can be regarded as a pivotal real-time input medium for human-computer communication, which is especially important for people with physical disability. In order to improve the reliability, mobility, and usability of eye tracking technique in user-computer dialogue, a novel eye control system with integrating both mouse and keyboard functions is proposed in this paper. The proposed system focuses on providing a simple and convenient interactive mode by only using user's eye. The usage flow of the proposed system is designed to perfectly follow human natural habits. Additionally, a magnifier module is proposed to allow the accurate operation. In the experiment, two interactive tasks with different difficulty (searching article and browsing multimedia web) were done to compare the proposed eye control tool with an existing system. The Technology Acceptance Model (TAM) measures are used to evaluate the perceived effectiveness of our system. It is demonstrated that the proposed system is very effective with regard to usability and interface design.

Position calibration of a 3-DOF hand-controller with hybrid structure

NASA Astrophysics Data System (ADS)

Zhu, Chengcheng; Song, Aiguo

2017-09-01

A hand-controller is a human-robot interactive device, which measures the 3-DOF (Degree of Freedom) position of the human hand and sends it as a command to control robot movement. The device also receives 3-DOF force feedback from the robot and applies it to the human hand. Thus, the precision of 3-DOF position measurements is a key performance factor for hand-controllers. However, when using a hybrid type 3-DOF hand controller, various errors occur and are considered originating from machining and assembly variations within the device. This paper presents a calibration method to improve the position tracking accuracy of hybrid type hand-controllers by determining the actual size of the hand-controller parts. By re-measuring and re-calibrating this kind of hand-controller, the actual size of the key parts that cause errors is determined. Modifying the formula parameters with the actual sizes, which are obtained in the calibrating process, improves the end position tracking accuracy of the device.

Using a partial sum method and GPS tracking data to identify area restricted search by artisanal fishers at moored fish aggregating devices in the Commonwealth of Dominica.

PubMed

Alvard, Michael; Carlson, David; McGaffey, Ethan

2015-01-01

Foragers must often travel from a central place to exploit aggregations of prey. These patches can be identified behaviorally when a forager shifts from travel to area restricted search, identified by a decrease in speed and an increase in sinuosity of movement. Faster, more directed movement is associated with travel. Differentiating foraging behavior at patches from travel to patches is important for a variety of research questions and has now been made easier by the advent of small, GPS devices that can track forager movement with high resolution. In the summer and fall of 2012, movement data were collected from GPS devices placed on foraging trips originating in the artisanal fishing village of Desa Ikan (pseudonym), on the east coast of the Caribbean island nation of the Commonwealth Dominica. Moored FADs are human-made structures anchored to the ocean floor with fish attraction material on or near the surface designed to effectively create a resource patch. The ultimate goal of the research is to understand how property rights are emerging after the introduction of fish aggregating device (FAD) technology at the site in 1999. This paper reports on research to identify area-restricted search foraging behavior at FAD patches. For 22 foraging trips simultaneous behavioral observations were made to ground-truth the GPS movement data. Using a cumulative sum method, area restricted search was identified as negative deviations from the mean travel speed and the method was able to correctly identify FAD patches in every case.

Using a Partial Sum Method and GPS Tracking Data to Identify Area Restricted Search by Artisanal Fishers at Moored Fish Aggregating Devices in the Commonwealth of Dominica

PubMed Central

Alvard, Michael; Carlson, David; McGaffey, Ethan

2015-01-01

Foragers must often travel from a central place to exploit aggregations of prey. These patches can be identified behaviorally when a forager shifts from travel to area restricted search, identified by a decrease in speed and an increase in sinuosity of movement. Faster, more directed movement is associated with travel. Differentiating foraging behavior at patches from travel to patches is important for a variety of research questions and has now been made easier by the advent of small, GPS devices that can track forager movement with high resolution. In the summer and fall of 2012, movement data were collected from GPS devices placed on foraging trips originating in the artisanal fishing village of Desa Ikan (pseudonym), on the east coast of the Caribbean island nation of the Commonwealth Dominica. Moored FADs are human-made structures anchored to the ocean floor with fish attraction material on or near the surface designed to effectively create a resource patch. The ultimate goal of the research is to understand how property rights are emerging after the introduction of fish aggregating device (FAD) technology at the site in 1999. This paper reports on research to identify area-restricted search foraging behavior at FAD patches. For 22 foraging trips simultaneous behavioral observations were made to ground-truth the GPS movement data. Using a cumulative sum method, area restricted search was identified as negative deviations from the mean travel speed and the method was able to correctly identify FAD patches in every case. PMID:25647288

Design and development of data glove based on printed polymeric sensors and Zigbee networks for Human-Computer Interface.

PubMed

Tongrod, Nattapong; Lokavee, Shongpun; Watthanawisuth, Natthapol; Tuantranont, Adisorn; Kerdcharoen, Teerakiat

2013-03-01

Current trends in Human-Computer Interface (HCI) have brought on a wave of new consumer devices that can track the motion of our hands. These devices have enabled more natural interfaces with computer applications. Data gloves are commonly used as input devices, equipped with sensors that detect the movements of hands and communication unit that interfaces those movements with a computer. Unfortunately, the high cost of sensor technology inevitably puts some burden to most general users. In this research, we have proposed a low-cost data glove concept based on printed polymeric sensor to make pressure and bending sensors fabricated by a consumer ink-jet printer. These sensors were realized using a conductive polymer (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) [PEDOT:PSS]) thin film printed on glossy photo paper. Performance of these sensors can be enhanced by addition of dimethyl sulfoxide (DMSO) into the aqueous dispersion of PEDOT:PSS. The concept of surface resistance was successfully adopted for the design and fabrication of sensors. To demonstrate the printed sensors, we constructed a data glove using such sensors and developed software for real time hand tracking. Wireless networks based on low-cost Zigbee technology were used to transfer data from the glove to a computer. To our knowledge, this is the first report on low cost data glove based on paper pressure sensors. This low cost implementation of both sensors and communication network as proposed in this paper should pave the way toward a widespread implementation of data glove for real-time hand tracking applications.

Ultrasonic ranging for the oculometer

NASA Technical Reports Server (NTRS)

Guy, W. J.

1981-01-01

Ultrasonic tracking techniques are investigated for an oculometer. Two methods are reported in detail. The first is based on measurements of time from the start of a transmit burst to a received echo. Knowing the sound velocity, distance can be calculated. In the second method, a continuous signal is transmitted. Target movement causes phase shifting of the echo. By accumulating these phase shifts, tracking from a set point can be achieved. Both systems have problems with contoured targets, but work well on flat plates and the back of a human head. Also briefly reported is an evaluation of an ultrasonic ranging system. Interface circuits make this system compatible with the echo time design. While the system is consistently accurate, it has a beam too narrow for oculometer use. Finally, comments are provided on a tracking system using the Doppler frequency shift to give range data.

An MR-compatible gyroscope-based arm movement tracking system.

PubMed

Shirinbayan, S Iman; Rieger, Jochem W

2017-03-15

Functional magnetic resonance imaging is well suited to link neural population activation with movement parameters of complex natural arm movements. However, currently existing MR-compatible arm tracking devices are not constructed to measure arm joint movement parameters of unrestricted movements. Therefore, to date most research focuses on simple arm movements or includes very little knowledge about the actual movement kinematics. We developed a low cost gyroscope-based arm movement tracking system (GAMTS) that features MR-compatibility. The system consists of dual-axis analogue gyroscopes that measure rotations of upper and lower arm joints. After MR artifact reduction, the rotation angles of the individual arm joints are calculated and used to animate a realistic arm model that is implemented in the OpenSim platform. The OpenSim platform can then provide the kinematics of any point on the arm model. In order to demonstrate the capabilities of the system, we first assessed the quality of reconstructed wrist movements in a low-noise environment where typical MR-related problems are absent and finally, we validated the reconstruction in the MR environment. The system provides the kinematics of the whole arm when natural unrestricted arm movements are performed inside the MR-scanner. The GAMTS is reliably capable of reconstructing the kinematics of trajectories and the reconstruction error is small in comparison with the movement induced variation of speed, displacement, and rotation. Moreover, the system can be used to probe brain areas for their correlation with movement kinematics. Copyright © 2017 Elsevier B.V. All rights reserved.

SU-E-T-603: Analysis of Optical Tracked Head Inter-Fraction Movements Within Masks to Access Intracranial Immobilization Techniques in Proton Therapy

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

Hsi, W; Zeidan, O

2014-06-01

Purpose: We present a quantitative methodology utilizing an optical tracking system for monitoring head inter-fraction movements within brain masks to assess the effectiveness of two intracranial immobilization techniques. Methods and Materials: A 3-point-tracking method was developed to measure the mask location for a treatment field at each fraction. Measured displacement of mask location to its location at first fraction is equivalent to the head movement within the mask. Head movements for each of treatment fields were measured over about 10 fractions at each patient for seven patients; five treated in supine and two treated in prone. The Q-fix Base-of-Skull headmore » frame was used in supine while the CIVCO uni-frame baseplate was used in prone. Displacements of recoded couch position of each field post imaging at each fraction were extracted for those seven patients. Standard deviation (S.D.) of head movements and couch displacements was scored for statistical analysis. Results: The accuracy of 3PtTrack method was within 1.0 mm by phantom measurements. Patterns of head movement and couch displacement were similar for patients treated in either supine or prone. In superior-inferior direction, mean value of scored standard deviations over seven patients were 1.6 mm and 3.4 mm for the head movement and the couch displacement, respectively. The result indicated that the head movement combined with a loose fixation between the mask-to-head frame results large couch displacements for each patient, and also large variation between patients. However, the head movement is the main cause for the couch displacement with similar magnitude of around 1.0 mm in anterior-posterior and lateral directions. Conclusions: Optical-tracking methodology independently quantifying head movements could improve immobilization devices by correctly acting on causes for head motions within mask. A confidence in the quality of intracranial immobilization techniques could be more efficient by eliminating the need for frequent imaging.« less

Alcohol and disorientation-responses. VI, Effects of alcohol on eye movements and tracking performance during laboratory angular accelerations about the yaw and pitch axes.

DOT National Transportation Integrated Search

1972-12-01

Alcohol ingestion interferes with visual control of vestibular eye movements and thereby produces significant decrements in performance at a compensatory tracking task during oscillation about the yaw axis; significant or consistent decrements in per...

A Method for Recognizing State of Finger Flexure and Extension

NASA Astrophysics Data System (ADS)

Terado, Toshihiko; Fujiwara, Osamu

In our country, the handicapped and the elderly people in bed increase rapidly. In the bedridden person’s daily life, there may be limitations in the physical movement and the means of mutual communication. For the support of their comfortable daily lives, therefore, the development of human interface equipment becomes an important task. The equipment of this kind is being already developed by means of laser beam, eye-tracking, breathing motion and myo-electric signals, while the attachment and handling are normally not so easy. In this study, paying attention to finger motion, we have developed human interface equipment easily attached to the body, which enables one to measure the finger flexure and extension for mutual communication. The state of finger flexure and extension is identified by a threshold level analysis from the 3D-locus data for the finger movement, which can be measured through the infrared rays from the LED markers attached to a glove with the previously developed prototype system. We then have confirmed from an experiment that nearly 100% recognition for the finger movement can be achieved.

Effectiveness of an automatic tracking software in underwater motion analysis.

PubMed

Magalhaes, Fabrício A; Sawacha, Zimi; Di Michele, Rocco; Cortesi, Matteo; Gatta, Giorgio; Fantozzi, Silvia

2013-01-01

Tracking of markers placed on anatomical landmarks is a common practice in sports science to perform the kinematic analysis that interests both athletes and coaches. Although different software programs have been developed to automatically track markers and/or features, none of them was specifically designed to analyze underwater motion. Hence, this study aimed to evaluate the effectiveness of a software developed for automatic tracking of underwater movements (DVP), based on the Kanade-Lucas-Tomasi feature tracker. Twenty-one video recordings of different aquatic exercises (n = 2940 markers' positions) were manually tracked to determine the markers' center coordinates. Then, the videos were automatically tracked using DVP and a commercially available software (COM). Since tracking techniques may produce false targets, an operator was instructed to stop the automatic procedure and to correct the position of the cursor when the distance between the calculated marker's coordinate and the reference one was higher than 4 pixels. The proportion of manual interventions required by the software was used as a measure of the degree of automation. Overall, manual interventions were 10.4% lower for DVP (7.4%) than for COM (17.8%). Moreover, when examining the different exercise modes separately, the percentage of manual interventions was 5.6% to 29.3% lower for DVP than for COM. Similar results were observed when analyzing the type of marker rather than the type of exercise, with 9.9% less manual interventions for DVP than for COM. In conclusion, based on these results, the developed automatic tracking software presented can be used as a valid and useful tool for underwater motion analysis. Key PointsThe availability of effective software for automatic tracking would represent a significant advance for the practical use of kinematic analysis in swimming and other aquatic sports.An important feature of automatic tracking software is to require limited human interventions and supervision, thus allowing short processing time.When tracking underwater movements, the degree of automation of the tracking procedure is influenced by the capability of the algorithm to overcome difficulties linked to the small target size, the low image quality and the presence of background clutters.The newly developed feature-tracking algorithm has shown a good automatic tracking effectiveness in underwater motion analysis with significantly smaller percentage of required manual interventions when compared to a commercial software.

Current transport of leatherback sea turtles (Dermochelys coriacea) in the ocean.

PubMed

Luschi, P; Sale, A; Mencacci, R; Hughes, G R; Lutjeharms, J R E; Papi, F

2003-11-07

While the long-distance movements of pelagic vertebrates are becoming known thanks to satellite telemetry, the factors determining their courses have hardly been investigated. We have analysed the effects of oceanographic factors on the post-nesting movements of three satellite-tracked leatherback turtles (Dermochelys coriacea) moving in the southwest Indian Ocean. By superimposing the turtle tracks on contemporaneous images of sea-surface temperatures and sea height anomalies, we show that currentrelated features dominate the shape of the reconstructed routes. After an initial offshore movement, turtles moved along straight routes when in the core of the current, or executed loops within eddies. Large parts of the routes were strikingly similar to those of surface drifters tracked in the same region. These findings document that long-lasting oceanic movements of marine turtles may be shaped by oceanic currents.

Current transport of leatherback sea turtles (Dermochelys coriacea) in the ocean.

PubMed Central

Luschi, P; Sale, A; Mencacci, R; Hughes, G R; Lutjeharms, J R E; Papi, F

2003-01-01

While the long-distance movements of pelagic vertebrates are becoming known thanks to satellite telemetry, the factors determining their courses have hardly been investigated. We have analysed the effects of oceanographic factors on the post-nesting movements of three satellite-tracked leatherback turtles (Dermochelys coriacea) moving in the southwest Indian Ocean. By superimposing the turtle tracks on contemporaneous images of sea-surface temperatures and sea height anomalies, we show that currentrelated features dominate the shape of the reconstructed routes. After an initial offshore movement, turtles moved along straight routes when in the core of the current, or executed loops within eddies. Large parts of the routes were strikingly similar to those of surface drifters tracked in the same region. These findings document that long-lasting oceanic movements of marine turtles may be shaped by oceanic currents. PMID:14667360

Movements of juvenile Gyrfalcons from western and interior Alaska following departure from their natal areas

USGS Publications Warehouse

McIntyre, Carol L.; Douglas, David C.; Adams, Layne G.

2009-01-01

Juvenile raptors often travel thousands of kilometers from the time they leave their natal areas to the time they enter a breeding population. Documenting movements and identifying areas used by raptors before they enter a breeding population is important for understanding the factors that influence their survival. In North America, juvenile Gyrfalcons (Falco rusticolus) are routinely observed outside the species' breeding range during the nonbreeding season, but the natal origins of these birds are rarely known. We used satellite telemetry to track the movements of juvenile Gyrfalcons during their first months of independence. We instrumented nestlings with lightweight satellite transmitters within 10 d of estimated fledging dates on the Seward Peninsula in western Alaska and in Denali National Park (Denali) in interior Alaska. Gyrfalcons spent an average of 41.4 ± 6.1 d (range  =  30–50 d) in their natal areas after fledging. The mean departure date from natal areas was 27 August ± 6.4 d. We tracked 15 individuals for an average of 70.5 ± 28.1 d post-departure; Gyrfalcons moved from 105 to 4299 km during this period and tended to move greater distances earlier in the tracking period than later in the tracking period. Gyrfalcons did not establish temporary winter ranges within the tracking period. We identified several movement patterns among Gyrfalcons, including unidirectional long-distance movements, multidirectional long- and short-distance movements, and shorter movements within a local region. Gyrfalcons from the Seward Peninsula remained in western Alaska or flew to eastern Russia with no movements into interior Alaska. In contrast, Gyrfalcons from Denali remained in interior Alaska, flew to northern and western Alaska, or flew to northern Alberta. Gyrfalcons from both study areas tended to move to coastal, riparian, and wetland areas during autumn and early winter. Because juvenile Gyrfalcons dispersed over a large geographic area and across three international boundaries, conservation efforts should focus on both regional and international scales.

Effects of reward on the accuracy and dynamics of smooth pursuit eye movements.

PubMed

Brielmann, Aenne A; Spering, Miriam

2015-08-01

Reward modulates behavioral choices and biases goal-oriented behavior, such as eye or hand movements, toward locations or stimuli associated with higher rewards. We investigated reward effects on the accuracy and timing of smooth pursuit eye movements in 4 experiments. Eye movements were recorded in participants tracking a moving visual target on a computer monitor. Before target motion onset, a monetary reward cue indicated whether participants could earn money by tracking accurately, or whether the trial was unrewarded (Experiments 1 and 2, n = 11 each). Reward significantly improved eye-movement accuracy across different levels of task difficulty. Improvements were seen even in the earliest phase of the eye movement, within 70 ms of tracking onset, indicating that reward impacts visual-motor processing at an early level. We obtained similar findings when reward was not precued but explicitly associated with the pursuit target (Experiment 3, n = 16); critically, these results were not driven by stimulus prevalence or other factors such as preparation or motivation. Numerical cues (Experiment 4, n = 9) were not effective. (c) 2015 APA, all rights reserved).

Voluntary control of arm movement in athetotic patients

PubMed Central

Neilson, Peter D.

1974-01-01

Visual tracking tests have been employed to provide a quantitative description of voluntary control of arm movement in a group of patients suffering from athetoid cerebral palsy. Voluntary control was impaired in all patients in a characteristic manner. Maximum velocity and acceleration of arm movement were reduced to about 30-50% of their values in normal subjects and the time lag of the response to a visual stimulus was two or three times greater than in normals. Tracking transmission characteristics indicated a degree of underdamping which was not presnet in normal or spastic patients. This underdamping could be responsible for a low frequency (0·3-0·6 Hz) transient oscillation in elbow-angle movements associated with sudden voluntary movement. The maximum frequency at which patients could produce a coherent tracking response was only 50% of that in normal subjects and the relationship between the electromyogram and muscle contraction indicated that the mechanical load on the biceps muscle was abnormal, possibly due to increased stiffness of joint movement caused by involuntary activity in agonist and antagonist muscles acting across the joint. Images PMID:4362243

Mapping intra-urban transmission risk of dengue fever with big hourly cellphone data.

PubMed

Mao, Liang; Yin, Ling; Song, Xiaoqing; Mei, Shujiang

2016-10-01

Cellphone tracking has been recently integrated into risk assessment of disease transmission, because travel behavior of disease carriers can be depicted in unprecedented details. Still in its infancy, such an integration has been limited to: 1) risk assessment only at national and provincial scales, where intra-urban human movements are neglected, and 2) using irregularly logged cellphone data that miss numerous user movements. Furthermore, few risk assessments have considered positional uncertainty of cellphone data. This study proposed a new framework for mapping intra-urban disease risk with regularly logged cellphone tracking data, taking the dengue fever in Shenzhen city as an example. Hourly tracking records of 5.85 million cellphone users, combined with the random forest classification and mosquito activities, were utilized to estimate the local transmission risk of dengue fever and the importation risk through travels. Stochastic simulations were further employed to quantify the uncertainty of risk. The resultant maps suggest targeted interventions to maximally reduce dengue cases exported to other places, as well as appropriate interventions to contain risk in places that import them. Given the popularity of cellphone use in urbanized areas, this framework can be adopted by other cities to design spatio-temporally resolved programs for disease control. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparing speech and nonspeech context effects across timescales in coarticulatory contexts.

PubMed

Viswanathan, Navin; Kelty-Stephen, Damian G

2018-02-01

Context effects are ubiquitous in speech perception and reflect the ability of human listeners to successfully perceive highly variable speech signals. In the study of how listeners compensate for coarticulatory variability, past studies have used similar effects speech and tone analogues of speech as strong support for speech-neutral, general auditory mechanisms for compensation for coarticulation. In this manuscript, we revisit compensation for coarticulation by replacing standard button-press responses with mouse-tracking responses and examining both standard geometric measures of uncertainty as well as newer information-theoretic measures that separate fast from slow mouse movements. We found that when our analyses were restricted to end-state responses, tones and speech contexts appeared to produce similar effects. However, a more detailed time-course analysis revealed systematic differences between speech and tone contexts such that listeners' responses to speech contexts, but not to tone contexts, changed across the experimental session. Analyses of the time course of effects within trials using mouse tracking indicated that speech contexts elicited fewer x-position flips but more area under the curve (AUC) and maximum deviation (MD), and they did so in the slower portions of mouse-tracking movements. Our results indicate critical differences between the time course of speech and nonspeech context effects and that general auditory explanations, motivated by their apparent similarity, be reexamined.

Virtual targeting in three-dimensional space with sound and light interference

NASA Astrophysics Data System (ADS)

Chua, Florence B.; DeMarco, Robert M.; Bergen, Michael T.; Short, Kenneth R.; Servatius, Richard J.

2006-05-01

Law enforcement and the military are critically concerned with the targeting and firing accuracy of opponents. Stimuli which impede opponent targeting and firing accuracy can be incorporated into defense systems. An automated virtual firing range was developed to assess human targeting accuracy under conditions of sound and light interference, while avoiding dangers associated with live fire. This system has the ability to quantify sound and light interference effects on targeting and firing accuracy in three dimensions. This was achieved by development of a hardware and software system that presents the subject with a sound or light target, preceded by a sound or light interference. SonyXplod. TM 4-way speakers present sound interference and sound targeting. The Martin ® MiniMAC TM Profile operates as a source of light interference, while a red laser light serves as a target. A tracking system was created to monitor toy gun movement and firing in three-dimensional space. Data are collected via the Ascension ® Flock of Birds TM tracking system and a custom National Instrument ® LabVIEW TM 7.0 program to monitor gun movement and firing. A test protocol examined system parameters. Results confirm that the system enables tracking of virtual shots from a fired simulation gun to determine shot accuracy and location in three dimensions.

Receptive fields for smooth pursuit eye movements and motion perception.

PubMed

Debono, Kurt; Schütz, Alexander C; Spering, Miriam; Gegenfurtner, Karl R

2010-12-01

Humans use smooth pursuit eye movements to track moving objects of interest. In order to track an object accurately, motion signals from the target have to be integrated and segmented from motion signals in the visual context. Most studies on pursuit eye movements used small visual targets against a featureless background, disregarding the requirements of our natural visual environment. Here, we tested the ability of the pursuit and the perceptual system to integrate motion signals across larger areas of the visual field. Stimuli were random-dot kinematograms containing a horizontal motion signal, which was perturbed by a spatially localized, peripheral motion signal. Perturbations appeared in a gaze-contingent coordinate system and had a different direction than the main motion including a vertical component. We measured pursuit and perceptual direction discrimination decisions and found that both steady-state pursuit and perception were influenced most by perturbation angles close to that of the main motion signal and only in regions close to the center of gaze. The narrow direction bandwidth (26 angular degrees full width at half height) and small spatial extent (8 degrees of visual angle standard deviation) correspond closely to tuning parameters of neurons in the middle temporal area (MT). Copyright © 2010 Elsevier Ltd. All rights reserved.

A helmet mounted display to adapt the telerobotic environment to human vision

NASA Technical Reports Server (NTRS)

Tharp, Gregory; Liu, Andrew; Yamashita, Hitomi; Stark, Lawrence

1990-01-01

A Helmet Mounted Display system has been developed. It provides the capability to display stereo images with the viewpoint tied to subjects' head orientation. The type of display might be useful in a telerobotic environment provided the correct operating parameters are known. The effects of update frequency were tested using a 3D tracking task. The effects of blur were tested using both tracking and pick-and-place tasks. For both, researchers found that operator performance can be degraded if the correct parameters are not used. Researchers are also using the display to explore the use of head movements as part of gaze as subjects search their visual field for target objects.

A soft biomimetic tongue: model reconstruction and motion tracking

NASA Astrophysics Data System (ADS)

Lu, Xuanming; Xu, Weiliang; Li, Xiaoning

2016-04-01

A bioinspired robotic tongue which is actuated by a network of compressed air is proposed for the purpose of mimicking the movements of human tongue. It can be applied in the fields such as medical science and food engineering. The robotic tongue is made of two kinds of silicone rubber Ecoflex 0030 and PDMS with the shape simplified from real human tongue. In order to characterize the robotic tongue, a series of experiments were carried out. Laser scan was applied to reconstruct the static model of robotic tongue when it was under pressurization. After each scan, the robotic tongue was scattered into dense points in the same 3D coordinate system and the coordinates of each point were recorded. Motion tracking system (OptiTrack) was used to track and record the whole process of deformation dynamically during the loading and unloading phase. In the experiments, five types of deformation were achieved including roll-up, roll-down, elongation, groove and twist. Utilizing the discrete points generated by laser scan, the accurate parameterized outline of robotic tongue under different pressure was obtained, which could help demonstrate the static characteristic of robotic tongue. The precise deformation process under one pressure was acquired through the OptiTrack system which contains a series of digital cameras, markers on the robotic tongue and a set of hardware and software for data processing. By means of tracking and recording different process of deformation under different pressure, the dynamic characteristic of robotic tongue could be achieved.

Effects of wrist tendon vibration on arm tracking in people poststroke.

PubMed

Conrad, Megan O; Scheidt, Robert A; Schmit, Brian D

2011-09-01

The goal of this study was to evaluate the influence of wrist tendon vibration on a multijoint elbow/shoulder tracking task. We hypothesized that tendon vibration applied at the wrist musculature would improve upper arm tracking performance in chronic stroke survivors through increased, Ia-afferent feedback to the central nervous system (CNS). To test this hypothesis, 10 chronic stroke and 5 neurologically intact subjects grasped the handle of a planar robot as they tracked a target through a horizontal figure-8 pattern. A total of 36 trials were completed by each subject. During the middle trials, 70-Hz tendon vibration was applied at the wrist flexor tendons. Position, velocity, and electromyography data were evaluated to compare the quality of arm movements before, during, and after trials with concurrent vibration. Despite tracking a target that moved at a constant velocity, hand trajectories appeared to be segmented, displaying alternating intervals of acceleration and deceleration. Segments were identifiable in tangential velocity data as single-peaked, bell-shaped speed pulses. When tendon vibration was applied at the wrist musculature, stroke subjects experienced improved tracking performance in that hand path lengths and peak speed variability decreased, whereas movement smoothness increased. These performance improvements were accompanied by decreases in the muscle activity during movement. Possible mechanisms behind improved movement control in response to tendon vibration may include improved sensorimotor integration or improved cortical modulation of spinal reflex activity.

Effects of wrist tendon vibration on arm tracking in people poststroke

PubMed Central

Conrad, Megan O.; Scheidt, Robert A.

2011-01-01

The goal of this study was to evaluate the influence of wrist tendon vibration on a multijoint elbow/shoulder tracking task. We hypothesized that tendon vibration applied at the wrist musculature would improve upper arm tracking performance in chronic stroke survivors through increased, Ia-afferent feedback to the central nervous system (CNS). To test this hypothesis, 10 chronic stroke and 5 neurologically intact subjects grasped the handle of a planar robot as they tracked a target through a horizontal figure-8 pattern. A total of 36 trials were completed by each subject. During the middle trials, 70-Hz tendon vibration was applied at the wrist flexor tendons. Position, velocity, and electromyography data were evaluated to compare the quality of arm movements before, during, and after trials with concurrent vibration. Despite tracking a target that moved at a constant velocity, hand trajectories appeared to be segmented, displaying alternating intervals of acceleration and deceleration. Segments were identifiable in tangential velocity data as single-peaked, bell-shaped speed pulses. When tendon vibration was applied at the wrist musculature, stroke subjects experienced improved tracking performance in that hand path lengths and peak speed variability decreased, whereas movement smoothness increased. These performance improvements were accompanied by decreases in the muscle activity during movement. Possible mechanisms behind improved movement control in response to tendon vibration may include improved sensorimotor integration or improved cortical modulation of spinal reflex activity. PMID:21697444

Home range and movements of American alligators (Alligator mississippiensis) in an estuary habitat

USGS Publications Warehouse

Fujisaki, Ikuko; Hart, Kristen M.; Mazzotti, Frank J.; Cherkiss, Michael S.; Sartain-Iverson, Autumn R.; Jeffery, Brian M.; Beauchamp, Jeffrey S.; Denton, Mathew J.

2014-01-01

This study reveals consistent use of estuary habitat by American alligators. The alligators showed variations in their movement pattern and seasonal habitat, with movement attributable to environmental factors. Although satellite-derived locations were more dispersed compared to locations collected using VHF radio-tags, data collected from VHF tracking omitted some habitat used for a short period of time, indicating the effectiveness of satellite telemetry to continuously track animals for ecosystem-scale studies.

Two-axis tracking using translation stages for a lens-to-channel waveguide solar concentrator.

PubMed

Liu, Yuxiao; Huang, Ran; Madsen, Christi K

2014-10-20

A two-axis tracking scheme designed for <250x concentration realized by a single-axis mechanical tracker and a translation stage is discussed. The translation stage is used for adjusting positions for seasonal sun movement. It has two-dimensional x-y tracking instead of horizontal movement x-only. This tracking method is compatible with planar waveguide solar concentrators. A prototype system with 50x concentration shows >75% optical efficiency throughout the year in simulation and >65% efficiency experimentally. This efficiency can be further improved by the use of anti-reflection layers and a larger waveguide refractive index.

Representational momentum for the human body: awkwardness matters, experience does not.

PubMed

Wilson, Margaret; Lancaster, Jessy; Emmorey, Karen

2010-08-01

Perception of the human body appears to involve predictive simulations that project forward to track unfolding body-motion events. Here we use representational momentum (RM) to investigate whether implicit knowledge of a learned arbitrary system of body movement such as sign language influences this prediction process, and how this compares to implicit knowledge of biomechanics. Experiment 1 showed greater RM for sign language stimuli in the correct direction of the sign than in the reverse direction, but unexpectedly this held true for non-signers as well as signers. Experiment 2 supported two biomechanical explanations for this result (an effect of downward movement, and an effect of the direction that the movement had actually been performed by the model), and Experiments 3 and 4 found no residual enhancement of RM in signers when these factors were controlled. In fact, surprisingly, the opposite was found: signers showed reduced RM for signs. Experiment 5 verified the effect of biomechanical knowledge by testing arm movements that are easy to perform in one direction but awkward in the reverse direction, and found greater RM for the easy direction. We conclude that while perceptual prediction is shaped by implicit knowledge of biomechanics (the awkwardness effect), it is surprisingly insensitive to expectations derived from learned movement patterns. Results are discussed in terms of recent findings on the mirror system. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Before your very eyes: the value and limitations of eye tracking in medical education.

PubMed

Kok, Ellen M; Jarodzka, Halszka

2017-01-01

Medicine is a highly visual discipline. Physicians from many specialties constantly use visual information in diagnosis and treatment. However, they are often unable to explain how they use this information. Consequently, it is unclear how to train medical students in this visual processing. Eye tracking is a research technique that may offer answers to these open questions, as it enables researchers to investigate such visual processes directly by measuring eye movements. This may help researchers understand the processes that support or hinder a particular learning outcome. In this article, we clarify the value and limitations of eye tracking for medical education researchers. For example, eye tracking can clarify how experience with medical images mediates diagnostic performance and how students engage with learning materials. Furthermore, eye tracking can also be used directly for training purposes by displaying eye movements of experts in medical images. Eye movements reflect cognitive processes, but cognitive processes cannot be directly inferred from eye-tracking data. In order to interpret eye-tracking data properly, theoretical models must always be the basis for designing experiments as well as for analysing and interpreting eye-tracking data. The interpretation of eye-tracking data is further supported by sound experimental design and methodological triangulation. © 2016 John Wiley & Sons Ltd and The Association for the Study of Medical Education.

Method of Menu Selection by Gaze Movement Using AC EOG Signals

NASA Astrophysics Data System (ADS)

Kanoh, Shin'ichiro; Futami, Ryoko; Yoshinobu, Tatsuo; Hoshimiya, Nozomu

A method to detect the direction and the distance of voluntary eye gaze movement from EOG (electrooculogram) signals was proposed and tested. In this method, AC-amplified vertical and horizontal transient EOG signals were classified into 8-class directions and 2-class distances of voluntary eye gaze movements. A horizontal and a vertical EOGs during eye gaze movement at each sampling time were treated as a two-dimensional vector, and the center of gravity of the sample vectors whose norms were more than 80% of the maximum norm was used as a feature vector to be classified. By the classification using the k-nearest neighbor algorithm, it was shown that the averaged correct detection rates on each subject were 98.9%, 98.7%, 94.4%, respectively. This method can avoid strict EOG-based eye tracking which requires DC amplification of very small signal. It would be useful to develop robust human interfacing systems based on menu selection for severely paralyzed patients.

Speech Motor Development during Acquisition of the Voicing Contrast

ERIC Educational Resources Information Center

Grigos, Maria I.; Saxman, John H.; Gordon, Andrew M.

2005-01-01

Lip and jaw movements were studied longitudinally in 19-month-old children as they acquired the voicing contrast for /p/ and /b/. A movement tracking system obtained lip and jaw kinematics as participants produced the target utterances /papa/ and /baba/. Laryngeal adjustments were also tracked through acoustically recorded voice onset time (VOT)…

Removing the Interdependency between Horizontal and Vertical Eye-Movement Components in Electrooculograms

PubMed Central

Chang, Won-Du; Cha, Ho-Seung; Im, Chang-Hwan

2016-01-01

This paper introduces a method to remove the unwanted interdependency between vertical and horizontal eye-movement components in electrooculograms (EOGs). EOGs have been widely used to estimate eye movements without a camera in a variety of human-computer interaction (HCI) applications using pairs of electrodes generally attached either above and below the eye (vertical EOG) or to the left and right of the eyes (horizontal EOG). It has been well documented that the vertical EOG component has less stability than the horizontal EOG one, making accurate estimation of the vertical location of the eyes difficult. To address this issue, an experiment was designed in which ten subjects participated. Visual inspection of the recorded EOG signals showed that the vertical EOG component is highly influenced by horizontal eye movements, whereas the horizontal EOG is rarely affected by vertical eye movements. Moreover, the results showed that this interdependency could be effectively removed by introducing an individual constant value. It is therefore expected that the proposed method can enhance the overall performance of practical EOG-based eye-tracking systems. PMID:26907271

Imaging and tracking HIV viruses in human cervical mucus

NASA Astrophysics Data System (ADS)

Boukari, Fatima; Makrogiannis, Sokratis; Nossal, Ralph; Boukari, Hacène

2016-09-01

We describe a systematic approach to image, track, and quantify the movements of HIV viruses embedded in human cervical mucus. The underlying motivation for this study is that, in HIV-infected adults, women account for more than half of all new cases and most of these women acquire the infection through heterosexual contact. The endocervix is believed to be a susceptible site for HIV entry. Cervical mucus, which coats the endocervix, should play a protective role against the viruses. Thus, we developed a methodology to apply time-resolved confocal microscopy to examine the motion of HIV viruses that were added to samples of untreated cervical mucus. From the images, we identified the viruses, tracked them over time, and calculated changes of the statistical mean-squared displacement (MSD) of each virus. Approximately half of tracked viruses appear constrained while the others show mobility with MSDs that are proportional to τα+ν2τ2, over time range τ, depicting a combination of anomalous diffusion (0<α<0.4) and flow-like behavior. The MSD data also reveal plateaus attributable to possible stalling of the viruses. Although a more extensive study is warranted, these results support the assumption of mucus being a barrier against the motion of these viruses.

Long-Distance and Frequent Movements of the Flying-Fox Pteropus poliocephalus: Implications for Management

PubMed Central

Roberts, Billie J.; Catterall, Carla P.; Eby, Peggy; Kanowski, John

2012-01-01

Flying-foxes (Pteropodidae) are large bats capable of long-distance flight. Many species are threatened; some are considered pests. Effective conservation and management of flying-foxes are constrained by lack of knowledge of their ecology, especially of movement patterns over large spatial scales. Using satellite telemetry, we quantified long-distance movements of the grey-headed flying-fox Pteropus poliocephalus among roost sites in eastern Australia. Fourteen adult males were tracked for 2–40 weeks (mean 25 weeks). Collectively, these individuals utilised 77 roost sites in an area spanning 1,075 km by 128 km. Movement patterns varied greatly between individuals, with some travelling long distances. Five individuals travelled cumulative distances >1,000 km over the study period. Five individuals showed net displacements >300 km during one month, including one movement of 500 km within 48 hours. Seasonal movements were consistent with facultative latitudinal migration in part of the population. Flying-foxes shifted roost sites frequently: 64% of roost visits lasted <5 consecutive days, although some individuals remained at one roost for several months. Modal 2-day distances between consecutive roosts were 21–50 km (mean 45 km, range 3–166 km). Of 13 individuals tracked for >12 weeks, 10 moved >100 km in one or more weeks. Median cumulative displacement distances over 1, 10 and 30 weeks were 0 km, 260 km and 821 km, respectively. On average, over increasing time-periods, one additional roost site was visited for each additional 100 km travelled. These findings explain why culling and relocation attempts have had limited success in resolving human-bat conflicts in Australia. Flying-foxes are highly mobile between camps and regularly travel long distances. Consequently, local control actions are likely to have only temporary effects on local flying-fox populations. Developing alternative methods to manage these conflicts remains an important challenge that should be informed by a better understanding of the species’ movement patterns. PMID:22880021

Measure and Analysis of a Gaze Position Using Infrared Light Technique

DTIC Science & Technology

2001-10-25

MEASURE AND ANALYSIS OF A GAZE POSITION USING INFRARED LIGHT TECHNIQUE Z. Ramdane-Cherif1,2, A. Naït-Ali2, J F. Motsch2, M. O. Krebs1 1INSERM E 01-17...also proposes a method to correct head movements. Keywords: eye movement, gaze tracking, visual scan path, spatial mapping. INTRODUCTION The eye gaze ...tracking has been used for clinical purposes to detect illnesses, such as nystagmus , unusual eye movements and many others [1][2][3]. It is also used

Covert enaction at work: Recording the continuous movements of visuospatial attention to visible or imagined targets by means of Steady-State Visual Evoked Potentials (SSVEPs).

PubMed

Gregori Grgič, Regina; Calore, Enrico; de'Sperati, Claudio

2016-01-01

Whereas overt visuospatial attention is customarily measured with eye tracking, covert attention is assessed by various methods. Here we exploited Steady-State Visual Evoked Potentials (SSVEPs) - the oscillatory responses of the visual cortex to incoming flickering stimuli - to record the movements of covert visuospatial attention in a way operatively similar to eye tracking (attention tracking), which allowed us to compare motion observation and motion extrapolation with and without eye movements. Observers fixated a central dot and covertly tracked a target oscillating horizontally and sinusoidally. In the background, the left and the right halves of the screen flickered at two different frequencies, generating two SSVEPs in occipital regions whose size varied reciprocally as observers attended to the moving target. The two signals were combined into a single quantity that was modulated at the target frequency in a quasi-sinusoidal way, often clearly visible in single trials. The modulation continued almost unchanged when the target was switched off and observers mentally extrapolated its motion in imagery, and also when observers pointed their finger at the moving target during covert tracking, or imagined doing so. The amplitude of modulation during covert tracking was ∼25-30% of that measured when observers followed the target with their eyes. We used 4 electrodes in parieto-occipital areas, but similar results were achieved with a single electrode in Oz. In a second experiment we tested ramp and step motion. During overt tracking, SSVEPs were remarkably accurate, showing both saccadic-like and smooth pursuit-like modulations of cortical responsiveness, although during covert tracking the modulation deteriorated. Covert tracking was better with sinusoidal motion than ramp motion, and better with moving targets than stationary ones. The clear modulation of cortical responsiveness recorded during both overt and covert tracking, identical for motion observation and motion extrapolation, suggests to include covert attention movements in enactive theories of mental imagery. Copyright © 2015 Elsevier Ltd. All rights reserved.

Research of maneuvering target prediction and tracking technology based on IMM algorithm

NASA Astrophysics Data System (ADS)

Cao, Zheng; Mao, Yao; Deng, Chao; Liu, Qiong; Chen, Jing

2016-09-01

Maneuvering target prediction and tracking technology is widely used in both military and civilian applications, the study of those technologies is all along the hotspot and difficulty. In the Electro-Optical acquisition-tracking-pointing system (ATP), the primary traditional maneuvering targets are ballistic target, large aircraft and other big targets. Those targets have the features of fast velocity and a strong regular trajectory and Kalman Filtering and polynomial fitting have good effects when they are used to track those targets. In recent years, the small unmanned aerial vehicles developed rapidly for they are small, nimble and simple operation. The small unmanned aerial vehicles have strong maneuverability in the observation system of ATP although they are close-in, slow and small targets. Moreover, those vehicles are under the manual operation, therefore, the acceleration of them changes greatly and they move erratically. So the prediction and tracking precision is low when traditional algorithms are used to track the maneuvering fly of those targets, such as speeding up, turning, climbing and so on. The interacting multiple model algorithm (IMM) use multiple models to match target real movement trajectory, there are interactions between each model. The IMM algorithm can switch model based on a Markov chain to adapt to the change of target movement trajectory, so it is suitable to solve the prediction and tracking problems of the small unmanned aerial vehicles because of the better adaptability of irregular movement. This paper has set up model set of constant velocity model (CV), constant acceleration model (CA), constant turning model (CT) and current statistical model. And the results of simulating and analyzing the real movement trajectory data of the small unmanned aerial vehicles show that the prediction and tracking technology based on the interacting multiple model algorithm can get relatively lower tracking error and improve tracking precision comparing with traditional algorithms.

What is the animal doing? Tools for exploring behavioural structure in animal movements.

PubMed

Gurarie, Eliezer; Bracis, Chloe; Delgado, Maria; Meckley, Trevor D; Kojola, Ilpo; Wagner, C Michael

2016-01-01

Movement data provide a window - often our only window - into the cognitive, social and biological processes that underlie the behavioural ecology of animals in the wild. Robust methods for identifying and interpreting distinct modes of movement behaviour are of great importance, but complicated by the fact that movement data are complex, multivariate and dependent. Many different approaches to exploratory analysis of movement have been developed to answer similar questions, and practitioners are often at a loss for how to choose an appropriate tool for a specific question. We apply and compare four methodological approaches: first passage time (FPT), Bayesian partitioning of Markov models (BPMM), behavioural change point analysis (BCPA) and a fitted multistate random walk (MRW) to three simulated tracks and two animal trajectories - a sea lamprey (Petromyzon marinus) tracked for 12 h and a wolf (Canis lupus) tracked for 1 year. The simulations - in which, respectively, velocity, tortuosity and spatial bias change - highlight the sensitivity of all methods to model misspecification. Methods that do not account for autocorrelation in the movement variables lead to spurious change points, while methods that do not account for spatial bias completely miss changes in orientation. When applied to the animal data, the methods broadly agree on the structure of the movement behaviours. Important discrepancies, however, reflect differences in the assumptions and nature of the outputs. Important trade-offs are between the strength of the a priori assumptions (low in BCPA, high in MRW), complexity of output (high in the BCPA, low in the BPMM and MRW) and explanatory potential (highest in the MRW). The animal track analysis suggests some general principles for the exploratory analysis of movement data, including ways to exploit the strengths of the various methods. We argue for close and detailed exploratory analysis of movement before fitting complex movement models. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

Mouse cursor movement and eye tracking data as an indicator of pathologists’ attention when viewing digital whole slide images

PubMed Central

Raghunath, Vignesh; Braxton, Melissa O.; Gagnon, Stephanie A.; Brunyé, Tad T.; Allison, Kimberly H.; Reisch, Lisa M.; Weaver, Donald L.; Elmore, Joann G.; Shapiro, Linda G.

2012-01-01

Context: Digital pathology has the potential to dramatically alter the way pathologists work, yet little is known about pathologists’ viewing behavior while interpreting digital whole slide images. While tracking pathologist eye movements when viewing digital slides may be the most direct method of capturing pathologists’ viewing strategies, this technique is cumbersome and technically challenging to use in remote settings. Tracking pathologist mouse cursor movements may serve as a practical method of studying digital slide interpretation, and mouse cursor data may illuminate pathologists’ viewing strategies and time expenditures in their interpretive workflow. Aims: To evaluate the utility of mouse cursor movement data, in addition to eye-tracking data, in studying pathologists’ attention and viewing behavior. Settings and Design: Pathologists (N = 7) viewed 10 digital whole slide images of breast tissue that were selected using a random stratified sampling technique to include a range of breast pathology diagnoses (benign/atypia, carcinoma in situ, and invasive breast cancer). A panel of three expert breast pathologists established a consensus diagnosis for each case using a modified Delphi approach. Materials and Methods: Participants’ foveal vision was tracked using SensoMotoric Instruments RED 60 Hz eye-tracking system. Mouse cursor movement was tracked using a custom MATLAB script. Statistical Analysis Used: Data on eye-gaze and mouse cursor position were gathered at fixed intervals and analyzed using distance comparisons and regression analyses by slide diagnosis and pathologist expertise. Pathologists’ accuracy (defined as percent agreement with the expert consensus diagnoses) and efficiency (accuracy and speed) were also analyzed. Results: Mean viewing time per slide was 75.2 seconds (SD = 38.42). Accuracy (percent agreement with expert consensus) by diagnosis type was: 83% (benign/atypia); 48% (carcinoma in situ); and 93% (invasive). Spatial coupling was close between eye-gaze and mouse cursor positions (highest frequency ∆x was 4.00px (SD = 16.10), and ∆y was 37.50px (SD = 28.08)). Mouse cursor position moderately predicted eye gaze patterns (Rx = 0.33 and Ry = 0.21). Conclusions: Data detailing mouse cursor movements may be a useful addition to future studies of pathologists’ accuracy and efficiency when using digital pathology. PMID:23372984

Mouse cursor movement and eye tracking data as an indicator of pathologists' attention when viewing digital whole slide images.

PubMed

Raghunath, Vignesh; Braxton, Melissa O; Gagnon, Stephanie A; Brunyé, Tad T; Allison, Kimberly H; Reisch, Lisa M; Weaver, Donald L; Elmore, Joann G; Shapiro, Linda G

2012-01-01

Digital pathology has the potential to dramatically alter the way pathologists work, yet little is known about pathologists' viewing behavior while interpreting digital whole slide images. While tracking pathologist eye movements when viewing digital slides may be the most direct method of capturing pathologists' viewing strategies, this technique is cumbersome and technically challenging to use in remote settings. Tracking pathologist mouse cursor movements may serve as a practical method of studying digital slide interpretation, and mouse cursor data may illuminate pathologists' viewing strategies and time expenditures in their interpretive workflow. To evaluate the utility of mouse cursor movement data, in addition to eye-tracking data, in studying pathologists' attention and viewing behavior. Pathologists (N = 7) viewed 10 digital whole slide images of breast tissue that were selected using a random stratified sampling technique to include a range of breast pathology diagnoses (benign/atypia, carcinoma in situ, and invasive breast cancer). A panel of three expert breast pathologists established a consensus diagnosis for each case using a modified Delphi approach. Participants' foveal vision was tracked using SensoMotoric Instruments RED 60 Hz eye-tracking system. Mouse cursor movement was tracked using a custom MATLAB script. Data on eye-gaze and mouse cursor position were gathered at fixed intervals and analyzed using distance comparisons and regression analyses by slide diagnosis and pathologist expertise. Pathologists' accuracy (defined as percent agreement with the expert consensus diagnoses) and efficiency (accuracy and speed) were also analyzed. Mean viewing time per slide was 75.2 seconds (SD = 38.42). Accuracy (percent agreement with expert consensus) by diagnosis type was: 83% (benign/atypia); 48% (carcinoma in situ); and 93% (invasive). Spatial coupling was close between eye-gaze and mouse cursor positions (highest frequency ∆x was 4.00px (SD = 16.10), and ∆y was 37.50px (SD = 28.08)). Mouse cursor position moderately predicted eye gaze patterns (Rx = 0.33 and Ry = 0.21). Data detailing mouse cursor movements may be a useful addition to future studies of pathologists' accuracy and efficiency when using digital pathology.

Directional asymmetries in human smooth pursuit eye movements.

PubMed

Ke, Sally R; Lam, Jessica; Pai, Dinesh K; Spering, Miriam

2013-06-27

Humans make smooth pursuit eye movements to bring the image of a moving object onto the fovea. Although pursuit accuracy is critical to prevent motion blur, the eye often falls behind the target. Previous studies suggest that pursuit accuracy differs between motion directions. Here, we systematically assess asymmetries in smooth pursuit. In experiment 1, binocular eye movements were recorded while observers (n = 20) tracked a small spot of light moving along one of four cardinal or diagonal axes across a featureless background. We analyzed pursuit latency, acceleration, peak velocity, gain, and catch-up saccade latency, number, and amplitude. In experiment 2 (n = 22), we examined the effects of spatial location and constrained stimulus motion within the upper or lower visual field. Pursuit was significantly faster (higher acceleration, peak velocity, and gain) and smoother (fewer and later catch-up saccades) in response to downward versus upward motion in both the upper and the lower visual fields. Pursuit was also more accurate and smoother in response to horizontal versus vertical motion. CONCLUSIONS. Our study is the first to report a consistent up-down asymmetry in human adults, regardless of visual field. Our findings suggest that pursuit asymmetries are adaptive responses to the requirements of the visual context: preferred motion directions (horizontal and downward) are more critical to our survival than nonpreferred ones.

Evolution of circadian rhythms: from bacteria to human.

PubMed

Bhadra, Utpal; Thakkar, Nirav; Das, Paromita; Pal Bhadra, Manika

2017-07-01

The human body persists in its rhythm as per its initial time zone, and transition always occur according to solar movements around the earth over 24 h. While traveling across different latitudes and longitudes, at the pace exceeding the earth's movement, the changes in the external cues exceed the level of toleration of the body's biological clock. This poses an alteration in our physiological activities of sleep-wake pattern, mental alertness, organ movement, and eating habits, causing them to temporarily lose the track of time. This is further re-synchronized with the physiological cues of the destination over time. The mechanism of resetting of the clocks with varying time zones and cues occur in organisms from bacteria to humans. It is the result of the evolution of different pathways and molecular mechanisms over the time. There has been evolution of numerous comprehensive mechanisms using various research tools to get a deeper insight into the rapid turnover of molecular mechanisms in various species. This review reports insights into the evolution of the circadian mechanism and its evolutionary shift which is vital and plays a major role in assisting different organisms to adapt in different zones and controls their internal biological clocks with changing external cues. Copyright © 2017 Elsevier B.V. All rights reserved.

Long-term GPS tracking of ocean sunfish Mola mola offers a new direction in fish monitoring.

PubMed

Sims, David W; Queiroz, Nuno; Humphries, Nicolas E; Lima, Fernando P; Hays, Graeme C

2009-10-09

Satellite tracking of large pelagic fish provides insights on free-ranging behaviour, distributions and population structuring. Up to now, such fish have been tracked remotely using two principal methods: direct positioning of transmitters by Argos polar-orbiting satellites, and satellite relay of tag-derived light-level data for post hoc track reconstruction. Error fields associated with positions determined by these methods range from hundreds of metres to hundreds of kilometres. However, low spatial accuracy of tracks masks important details, such as foraging patterns. Here we use a fast-acquisition global positioning system (Fastloc GPS) tag with remote data retrieval to track long-term movements, in near real time and position accuracy of <70 m, of the world's largest bony fish, the ocean sunfish Mola mola. Search-like movements occurred over at least three distinct spatial scales. At fine scales, sunfish spent longer in highly localised areas with faster, straighter excursions between them. These 'stopovers' during long-distance movement appear consistent with finding and exploiting food patches. This demonstrates the feasibility of GPS tagging to provide tracks of unparalleled accuracy for monitoring movements of large pelagic fish, and with nearly four times as many locations obtained by the GPS tag than by a conventional Argos transmitter. The results signal the potential of GPS-tagged pelagic fish that surface regularly to be detectors of resource 'hotspots' in the blue ocean and provides a new capability for understanding large pelagic fish behaviour and habitat use that is relevant to ocean management and species conservation.

Long-Term GPS Tracking of Ocean Sunfish Mola mola Offers a New Direction in Fish Monitoring

PubMed Central

Sims, David W.; Queiroz, Nuno; Humphries, Nicolas E.; Lima, Fernando P.; Hays, Graeme C.

2009-01-01

Satellite tracking of large pelagic fish provides insights on free-ranging behaviour, distributions and population structuring. Up to now, such fish have been tracked remotely using two principal methods: direct positioning of transmitters by Argos polar-orbiting satellites, and satellite relay of tag-derived light-level data for post hoc track reconstruction. Error fields associated with positions determined by these methods range from hundreds of metres to hundreds of kilometres. However, low spatial accuracy of tracks masks important details, such as foraging patterns. Here we use a fast-acquisition global positioning system (Fastloc GPS) tag with remote data retrieval to track long-term movements, in near real time and position accuracy of <70 m, of the world's largest bony fish, the ocean sunfish Mola mola. Search-like movements occurred over at least three distinct spatial scales. At fine scales, sunfish spent longer in highly localised areas with faster, straighter excursions between them. These ‘stopovers’ during long-distance movement appear consistent with finding and exploiting food patches. This demonstrates the feasibility of GPS tagging to provide tracks of unparalleled accuracy for monitoring movements of large pelagic fish, and with nearly four times as many locations obtained by the GPS tag than by a conventional Argos transmitter. The results signal the potential of GPS-tagged pelagic fish that surface regularly to be detectors of resource ‘hotspots’ in the blue ocean and provides a new capability for understanding large pelagic fish behaviour and habitat use that is relevant to ocean management and species conservation. PMID:19816576

Facial feature tracking: a psychophysiological measure to assess exercise intensity?

PubMed

Miles, Kathleen H; Clark, Bradley; Périard, Julien D; Goecke, Roland; Thompson, Kevin G

2018-04-01

The primary aim of this study was to determine whether facial feature tracking reliably measures changes in facial movement across varying exercise intensities. Fifteen cyclists completed three, incremental intensity, cycling trials to exhaustion while their faces were recorded with video cameras. Facial feature tracking was found to be a moderately reliable measure of facial movement during incremental intensity cycling (intra-class correlation coefficient = 0.65-0.68). Facial movement (whole face (WF), upper face (UF), lower face (LF) and head movement (HM)) increased with exercise intensity, from lactate threshold one (LT1) until attainment of maximal aerobic power (MAP) (WF 3464 ± 3364mm, P < 0.005; UF 1961 ± 1779mm, P = 0.002; LF 1608 ± 1404mm, P = 0.002; HM 849 ± 642mm, P < 0.001). UF movement was greater than LF movement at all exercise intensities (UF minus LF at: LT1, 1048 ± 383mm; LT2, 1208 ± 611mm; MAP, 1401 ± 712mm; P < 0.001). Significant medium to large non-linear relationships were found between facial movement and power output (r 2  = 0.24-0.31), HR (r 2  = 0.26-0.33), [La - ] (r 2  = 0.33-0.44) and RPE (r 2  = 0.38-0.45). The findings demonstrate the potential utility of facial feature tracking as a non-invasive, psychophysiological measure to potentially assess exercise intensity.

Roles of the Declive, Folium, and Tuber Cerebellar Vermian Lobules in Sportspeople

PubMed Central

Park, In Sung; Lee, Nam Joon

2018-01-01

The cerebellum plays vital roles in balance control and motor learning, including in saccadic adaptation and coordination. It consists of the vermis and two hemispheres and is anatomically separated into ten lobules that are designated as I–X. Although neuroimaging and clinical studies suggest that functions are compartmentalized within the cerebellum, the function of each cerebellar lobule is not fully understood. Electrophysiological and lesion studies in animals as well as neuroimaging and lesion studies in humans have revealed that vermian lobules VI and VII (declive, folium, and tuber) are critical for controlling postural balance, saccadic eye movements, and coordination. In addition, recent structural magnetic resonance imaging studies have revealed that these lobules are larger in elite basketball and short-track speed skaters. Furthermore, in female short-track speed skaters, the volume of this region is significantly correlated with static balance. This article reviews the function of vermian lobules VI and VII, focusing on the control of balance, eye movements, and coordination including coordination between the eyes and hands and bimanual coordination. PMID:29141275

Fiducial migration following small peripheral lung tumor image-guided CyberKnife stereotactic radiosurgery

NASA Astrophysics Data System (ADS)

Strulik, Konrad L.; Cho, Min H.; Collins, Brian T.; Khan, Noureen; Banovac, Filip; Slack, Rebecca; Cleary, Kevin

2008-03-01

To track respiratory motion during CyberKnife stereotactic radiosurgery in the lung, several (three to five) cylindrical gold fiducials are implanted near the planned target volume (PTV). Since these fiducials remain in the human body after treatment, we hypothesize that tracking fiducial movement over time may correlate with the tumor response to treatment and pulmonary fibrosis, thereby serving as an indicator of treatment success. In this paper, we investigate fiducial migration in 24 patients through examination of computed tomography (CT) volume images at four time points: pre-treatment, three, six, and twelve month post-treatment. We developed a MATLAB based GUI environment to display the images, identify the fiducials, and compute our performance measure. After we semi-automatically segmented and detected fiducial locations in CT images of the same patient over time, we identified them according to their configuration and introduced a relative performance measure (ACD: average center distance) to detect their migration. We found that the migration tended to result in a movement towards the fiducial center of the radiated tissue area (indicating tumor regression) and may potentially be linked to the patient prognosis.

Linear parameter varying identification of ankle joint intrinsic stiffness during imposed walking movements.

PubMed

Sobhani Tehrani, Ehsan; Jalaleddini, Kian; Kearney, Robert E

2013-01-01

This paper describes a novel model structure and identification method for the time-varying, intrinsic stiffness of human ankle joint during imposed walking (IW) movements. The model structure is based on the superposition of a large signal, linear, time-invariant (LTI) model and a small signal linear-parameter varying (LPV) model. The methodology is based on a two-step algorithm; the LTI model is first estimated using data from an unperturbed IW trial. Then, the LPV model is identified using data from a perturbed IW trial with the output predictions of the LTI model removed from the measured torque. Experimental results demonstrate that the method accurately tracks the continuous-time variation of normal ankle intrinsic stiffness when the joint position changes during the IW movement. Intrinsic stiffness gain decreases from full plantarflexion to near the mid-point of plantarflexion and then increases substantially as the ankle is dosriflexed.

Visuomotor Tracking Ability of Young Adult Speakers.

ERIC Educational Resources Information Center

Moon, Jerald B.; And Others

1993-01-01

Twenty-five normal young adult speakers tracked sinusoidal and unpredictable target signals using lower lip and jaw movement and fundamental frequency modulation. Tracking accuracy varied as a function of target frequency and articulator used to track. Results show the potential of visuomotor tracking tasks in the assessment of speech articulatory…

Target Selection by the Frontal Cortex during Coordinated Saccadic and Smooth Pursuit Eye Movements

ERIC Educational Resources Information Center

Srihasam, Krishna; Bullock, Daniel; Grossberg, Stephen

2009-01-01

Oculomotor tracking of moving objects is an important component of visually based cognition and planning. Such tracking is achieved by a combination of saccades and smooth-pursuit eye movements. In particular, the saccadic and smooth-pursuit systems interact to often choose the same target, and to maximize its visibility through time. How do…

Stable isotope analyses of feather amino acids identify penguin migration strategies at ocean basin scales.

PubMed

Polito, Michael J; Hinke, Jefferson T; Hart, Tom; Santos, Mercedes; Houghton, Leah A; Thorrold, Simon R

2017-08-01

Identifying the at-sea distribution of wide-ranging marine predators is critical to understanding their ecology. Advances in electronic tracking devices and intrinsic biogeochemical markers have greatly improved our ability to track animal movements on ocean-wide scales. Here, we show that, in combination with direct tracking, stable carbon isotope analysis of essential amino acids in tail feathers provides the ability to track the movement patterns of two, wide-ranging penguin species over ocean basin scales. In addition, we use this isotopic approach across multiple breeding colonies in the Scotia Arc to evaluate migration trends at a regional scale that would be logistically challenging using direct tracking alone. © 2017 The Author(s).

An extended Kalman filter for mouse tracking.

PubMed

Choi, Hongjun; Kim, Mingi; Lee, Onseok

2018-05-19

Animal tracking is an important tool for observing behavior, which is useful in various research areas. Animal specimens can be tracked using dynamic models and observation models that require several types of data. Tracking mouse has several barriers due to the physical characteristics of the mouse, their unpredictable movement, and cluttered environments. Therefore, we propose a reliable method that uses a detection stage and a tracking stage to successfully track mouse. The detection stage detects the surface area of the mouse skin, and the tracking stage implements an extended Kalman filter to estimate the state variables of a nonlinear model. The changes in the overall shape of the mouse are tracked using an oval-shaped tracking model to estimate the parameters for the ellipse. An experiment is conducted to demonstrate the performance of the proposed tracking algorithm using six video images showing various types of movement, and the ground truth values for synthetic images are compared to the values generated by the tracking algorithm. A conventional manual tracking method is also applied to compare across eight experimenters. Furthermore, the effectiveness of the proposed tracking method is also demonstrated by applying the tracking algorithm with actual images of mouse. Graphical abstract.

Mousetrap: An integrated, open-source mouse-tracking package.

PubMed

Kieslich, Pascal J; Henninger, Felix

2017-10-01

Mouse-tracking - the analysis of mouse movements in computerized experiments - is becoming increasingly popular in the cognitive sciences. Mouse movements are taken as an indicator of commitment to or conflict between choice options during the decision process. Using mouse-tracking, researchers have gained insight into the temporal development of cognitive processes across a growing number of psychological domains. In the current article, we present software that offers easy and convenient means of recording and analyzing mouse movements in computerized laboratory experiments. In particular, we introduce and demonstrate the mousetrap plugin that adds mouse-tracking to OpenSesame, a popular general-purpose graphical experiment builder. By integrating with this existing experimental software, mousetrap allows for the creation of mouse-tracking studies through a graphical interface, without requiring programming skills. Thus, researchers can benefit from the core features of a validated software package and the many extensions available for it (e.g., the integration with auxiliary hardware such as eye-tracking, or the support of interactive experiments). In addition, the recorded data can be imported directly into the statistical programming language R using the mousetrap package, which greatly facilitates analysis. Mousetrap is cross-platform, open-source and available free of charge from https://github.com/pascalkieslich/mousetrap-os .

A dynamic Brownian bridge movement model to estimate utilization distributions for heterogeneous animal movement.

PubMed

Kranstauber, Bart; Kays, Roland; Lapoint, Scott D; Wikelski, Martin; Safi, Kamran

2012-07-01

1. The recently developed Brownian bridge movement model (BBMM) has advantages over traditional methods because it quantifies the utilization distribution of an animal based on its movement path rather than individual points and accounts for temporal autocorrelation and high data volumes. However, the BBMM assumes unrealistic homogeneous movement behaviour across all data. 2. Accurate quantification of the utilization distribution is important for identifying the way animals use the landscape. 3. We improve the BBMM by allowing for changes in behaviour, using likelihood statistics to determine change points along the animal's movement path. 4. This novel extension, outperforms the current BBMM as indicated by simulations and examples of a territorial mammal and a migratory bird. The unique ability of our model to work with tracks that are not sampled regularly is especially important for GPS tags that have frequent failed fixes or dynamic sampling schedules. Moreover, our model extension provides a useful one-dimensional measure of behavioural change along animal tracks. 5. This new method provides a more accurate utilization distribution that better describes the space use of realistic, behaviourally heterogeneous tracks. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

The Middle East in 2015: The Impact of Regional Trends in U.S. Strategic Planning

DTIC Science & Technology

2002-07-01

longevity , the activation of a Syrian- Israeli track, or the American election cycle—will eliminate the need to provide economic assistance and investment...to do so. But the movement toward elected, albeit still largely consultative, bodies pioneered by Kuwait has been followed in more modest measure in...The trends described in these chapters reflect an appreciation of demography , the natural laws of economics, history, and the deter- mination of human

Satellite tracking of manta rays highlights challenges to their conservation.

PubMed

Graham, Rachel T; Witt, Matthew J; Castellanos, Dan W; Remolina, Francisco; Maxwell, Sara; Godley, Brendan J; Hawkes, Lucy A

2012-01-01

We describe the real-time movements of the last of the marine mega-vertebrate taxa to be satellite tracked - the giant manta ray (or devil fish, Manta birostris), the world's largest ray at over 6 m disc width. Almost nothing is known about manta ray movements and their environmental preferences, making them one of the least understood of the marine mega-vertebrates. Red listed by the International Union for the Conservation of Nature as 'Vulnerable' to extinction, manta rays are known to be subject to direct and incidental capture and some populations are declining. Satellite-tracked manta rays associated with seasonal upwelling events and thermal fronts off the Yucatan peninsula, Mexico, and made short-range shuttling movements, foraging along and between them. The majority of locations were received from waters shallower than 50 m deep, representing thermally dynamic and productive waters. Manta rays remained in the Mexican Exclusive Economic Zone for the duration of tracking but only 12% of tracking locations were received from within Marine Protected Areas (MPAs). Our results on the spatio-temporal distribution of these enigmatic rays highlight opportunities and challenges to management efforts.

Classification of Animal Movement Behavior through Residence in Space and Time.

PubMed

Torres, Leigh G; Orben, Rachael A; Tolkova, Irina; Thompson, David R

2017-01-01

Identification and classification of behavior states in animal movement data can be complex, temporally biased, time-intensive, scale-dependent, and unstandardized across studies and taxa. Large movement datasets are increasingly common and there is a need for efficient methods of data exploration that adjust to the individual variability of each track. We present the Residence in Space and Time (RST) method to classify behavior patterns in movement data based on the concept that behavior states can be partitioned by the amount of space and time occupied in an area of constant scale. Using normalized values of Residence Time and Residence Distance within a constant search radius, RST is able to differentiate behavior patterns that are time-intensive (e.g., rest), time & distance-intensive (e.g., area restricted search), and transit (short time and distance). We use grey-headed albatross (Thalassarche chrysostoma) GPS tracks to demonstrate RST's ability to classify behavior patterns and adjust to the inherent scale and individuality of each track. Next, we evaluate RST's ability to discriminate between behavior states relative to other classical movement metrics. We then temporally sub-sample albatross track data to illustrate RST's response to less resolved data. Finally, we evaluate RST's performance using datasets from four taxa with diverse ecology, functional scales, ecosystems, and data-types. We conclude that RST is a robust, rapid, and flexible method for detailed exploratory analysis and meta-analyses of behavioral states in animal movement data based on its ability to integrate distance and time measurements into one descriptive metric of behavior groupings. Given the increasing amount of animal movement data collected, it is timely and useful to implement a consistent metric of behavior classification to enable efficient and comparative analyses. Overall, the application of RST to objectively explore and compare behavior patterns in movement data can enhance our fine- and broad- scale understanding of animal movement ecology.

The Levitation Characteristics of MGB2 Plates on Tracks of Permanent Magnets

NASA Astrophysics Data System (ADS)

Perini, E.; Bassani, E.; Giunchi, G.

2010-04-01

The bulk MgB2 can be manufactured in large plates by an innovative process: the reactive liquid Mg infiltration (Mg-RLI). According to this process it is possible to produce, even at lab scale, plates of 10÷20 cm in lateral dimensions. The superconducting material resulting is very dense and, even if it is in polycrystalline form, it levitates with respect to Permanent Magnets (PM), like the textured YBCO samples, up to 35 K. In order to control the levitation forces and stiffnesses of an MgB2 plate (10×10×1 cm3) moving with respect to a track of PM's (NdFeB bars arranged in 4 lines according to an Halbach disposition and separated by Iron flux concentrators), we have used an instrumented Cryogenic Levitation Apparatus (CLA). We have studied different kind of movements of the PM's track with respect to the MgB2 plate. First, we consider the vertical movement, assumed z direction, which describes the properly levitation characteristics. Secondly, we consider two kinds of lateral movements of the track, assumed x direction, with the long size of the magnets either perpendicular or parallel to the movement direction. The resulting configurations simulate the main movements that a superconducting levitating vehicle will do in a real track, either of axial or of guidance type. The levitation axial forces, measured in Field Cooling or Zero Field Cooling conditions, indicate that at the distance between superconducting plate and PM's of 4 mm it is possible to have an overall levitating pressure of 7 N/cm2.

Effect of visual distraction and auditory feedback on patient effort during robot-assisted movement training after stroke

PubMed Central

2011-01-01

Background Practicing arm and gait movements with robotic assistance after neurologic injury can help patients improve their movement ability, but patients sometimes reduce their effort during training in response to the assistance. Reduced effort has been hypothesized to diminish clinical outcomes of robotic training. To better understand patient slacking, we studied the role of visual distraction and auditory feedback in modulating patient effort during a common robot-assisted tracking task. Methods Fourteen participants with chronic left hemiparesis from stroke, five control participants with chronic right hemiparesis and fourteen non-impaired healthy control participants, tracked a visual target with their arms while receiving adaptive assistance from a robotic arm exoskeleton. We compared four practice conditions: the baseline tracking task alone; tracking while also performing a visual distracter task; tracking with the visual distracter and sound feedback; and tracking with sound feedback. For the distracter task, symbols were randomly displayed in the corners of the computer screen, and the participants were instructed to click a mouse button when a target symbol appeared. The sound feedback consisted of a repeating beep, with the frequency of repetition made to increase with increasing tracking error. Results Participants with stroke halved their effort and doubled their tracking error when performing the visual distracter task with their left hemiparetic arm. With sound feedback, however, these participants increased their effort and decreased their tracking error close to their baseline levels, while also performing the distracter task successfully. These effects were significantly smaller for the participants who used their non-paretic arm and for the participants without stroke. Conclusions Visual distraction decreased participants effort during a standard robot-assisted movement training task. This effect was greater for the hemiparetic arm, suggesting that the increased demands associated with controlling an affected arm make the motor system more prone to slack when distracted. Providing an alternate sensory channel for feedback, i.e., auditory feedback of tracking error, enabled the participants to simultaneously perform the tracking task and distracter task effectively. Thus, incorporating real-time auditory feedback of performance errors might improve clinical outcomes of robotic therapy systems. PMID:21513561

Adaptive Control Responses to Behavioral Perturbation Based Upon the Insect

DTIC Science & Technology

2006-11-01

the legs. Visual Sensors Antennal Mechanosensors Antennal Chemosensors Descending Interneurons Controlling Yaw...animals, the antenna were moved back and forth several times with servo motors to identify units that respond to antennal movement in either direction or...role of antennal postures and movements in plume tracking behavior. To date, results have shown that male moths tracking plumes in different wind

Movement mysteries unveiled: spatial ecology of juvenile green sea turtles

USGS Publications Warehouse

Shaver, Donna J.; Hart, Kristen M.; Fujisaki, Ikuko; Rubio, Cynthia; Sartain-Iverson, Autumn R.; Lutterschmidt, William I.

2013-01-01

Locations of important foraging areas are not well defined for many marine species. Unraveling these mysteries is vital to develop conservation strategies for these species, many of which are threatened or endangered. Satellite-tracking is a tool that can reveal movement patterns at both broad and fine spatial scales, in all marine environments. This chapter presents records of the longest duration track of an individual juvenile green turtle (434 days) and highest number of tracking days in any juvenile green turtle study (5483 tracking days) published to date. In this chapter, we use spatial modeling techniques to describe movements and identify foraging areas for juvenile green turtles (Chelonia mydas) captured in a developmental habitat in south Texas, USA. Some green turtles established residency in the vicinity of their capture and release site, but most used a specific habitat feature (i.e., a jettied pass) to travel between the Gulf of Mexico and a nearby bay. Still others moved southward within the Gulf of Mexico into Mexican coastal waters, likely in response to decreasing water temperatures. These movements to waters off the coast of Mexico highlight the importance of international cooperation in restoration efforts undertaken on behalf of this imperiled species.

Potential Effects of Winter Navigation on Movements of Large Land Mammals in Eastern Lake Superior and Saint Mary’s River Area. Great Lakes-Saint Lawrence Seaway Navigation Season Extension Program

DTIC Science & Technology

1980-09-01

considered effects on deer, seasonal migrations, daily movements and direct mortality; the dispersal of wolves , bobcats, lynx, moose, coyotes and red foxes...literature and information search pertaining to movements and dispersal of wolves , coyotes, foxes, bobcats, lynx, deer, and moose, and local records of the...islands in Whitefish Bay tracks of foxes, deer and wolf were identified. The partially obliterated tracks of a pack of five wolves were observed near

M-Track: A New Software for Automated Detection of Grooming Trajectories in Mice

PubMed Central

Zhang, Lin

2016-01-01

Grooming is a complex and robust innate behavior, commonly performed by most vertebrate species. In mice, grooming consists of a series of stereotyped patterned strokes, performed along the rostro-caudal axis of the body. The frequency and duration of each grooming episode is sensitive to changes in stress levels, social interactions and pharmacological manipulations, and is therefore used in behavioral studies to gain insights into the function of brain regions that control movement execution and anxiety. Traditional approaches to analyze grooming rely on manually scoring the time of onset and duration of each grooming episode, and are often performed on grooming episodes triggered by stress exposure, which may not be entirely representative of spontaneous grooming in freely-behaving mice. This type of analysis is time-consuming and provides limited information about finer aspects of grooming behaviors, which are important to understand movement stereotypy and bilateral coordination in mice. Currently available commercial and freeware video-tracking software allow automated tracking of the whole body of a mouse or of its head and tail, not of individual forepaws. Here we describe a simple experimental set-up and a novel open-source code, named M-Track, for simultaneously tracking the movement of individual forepaws during spontaneous grooming in multiple freely-behaving mice. This toolbox provides a simple platform to perform trajectory analysis of forepaw movement during distinct grooming episodes. By using M-track we show that, in C57BL/6 wild type mice, the speed and bilateral coordination of the left and right forepaws remain unaltered during the execution of distinct grooming episodes. Stress exposure induces a profound increase in the length of the forepaw grooming trajectories. M-Track provides a valuable and user-friendly interface to streamline the analysis of spontaneous grooming in biomedical research studies. PMID:27636358

The Right Track for Vision Correction

NASA Technical Reports Server (NTRS)

2003-01-01

More and more people are putting away their eyeglasses and contact lenses as a result of laser vision correction surgery. LASIK, the most widely performed version of this surgical procedure, improves vision by reshaping the cornea, the clear front surface of the eye, using an excimer laser. One excimer laser system, Alcon s LADARVision 4000, utilizes a laser radar (LADAR) eye tracking device that gives it unmatched precision. During LASIK surgery, laser During LASIK surgery, laser pulses must be accurately placed to reshape the cornea. A challenge to this procedure is the patient s constant eye movement. A person s eyes make small, involuntary movements known as saccadic movements about 100 times per second. Since the saccadic movements will not stop during LASIK surgery, most excimer laser systems use an eye tracking device that measures the movements and guides the placement of the laser beam. LADARVision s eye tracking device stems from the LADAR technology originally developed through several Small Business Innovation Research (SBIR) contracts with NASA s Johnson Space Center and the U.S. Department of Defense s Ballistic Missile Defense Office (BMDO). In the 1980s, Johnson awarded Autonomous Technologies Corporation a Phase I SBIR contract to develop technology for autonomous rendezvous and docking of space vehicles to service satellites. During Phase II of the Johnson SBIR contract, Autonomous Technologies developed a prototype range and velocity imaging LADAR to demonstrate technology that could be used for this purpose.

The speed–curvature power law in Drosophila larval locomotion

PubMed Central

2016-01-01

We report the discovery that the locomotor trajectories of Drosophila larvae follow the power-law relationship between speed and curvature previously found in the movements of human and non-human primates. Using high-resolution behavioural tracking in controlled but naturalistic sensory environments, we tested the law in maggots tracing different trajectory types, from reaching-like movements to scribbles. For most but not all flies, we found that the law holds robustly, with an exponent close to three-quarters rather than to the usual two-thirds found in almost all human situations, suggesting dynamic effects adding on purely kinematic constraints. There are different hypotheses for the origin of the law in primates, one invoking cortical computations, another viscoelastic muscle properties coupled with central pattern generators. Our findings are consistent with the latter view and demonstrate that the law is possible in animals with nervous systems orders of magnitude simpler than in primates. Scaling laws might exist because natural selection favours processes that remain behaviourally efficient across a wide range of neural and body architectures in distantly related species. PMID:28120807

The speed-curvature power law in Drosophila larval locomotion.

PubMed

Zago, Myrka; Lacquaniti, Francesco; Gomez-Marin, Alex

2016-10-01

We report the discovery that the locomotor trajectories of Drosophila larvae follow the power-law relationship between speed and curvature previously found in the movements of human and non-human primates. Using high-resolution behavioural tracking in controlled but naturalistic sensory environments, we tested the law in maggots tracing different trajectory types, from reaching-like movements to scribbles. For most but not all flies, we found that the law holds robustly, with an exponent close to three-quarters rather than to the usual two-thirds found in almost all human situations, suggesting dynamic effects adding on purely kinematic constraints. There are different hypotheses for the origin of the law in primates, one invoking cortical computations, another viscoelastic muscle properties coupled with central pattern generators. Our findings are consistent with the latter view and demonstrate that the law is possible in animals with nervous systems orders of magnitude simpler than in primates. Scaling laws might exist because natural selection favours processes that remain behaviourally efficient across a wide range of neural and body architectures in distantly related species. © 2016 The Authors.

Attentional bias to betel quid cues: An eye tracking study.

PubMed

Shen, Bin; Chiu, Meng-Chun; Li, Shuo-Heng; Huang, Guo-Joe; Liu, Ling-Jun; Ho, Ming-Chou

2016-09-01

The World Health Organization regards betel quid as a human carcinogen, and DSM-IV and ICD-10 dependence symptoms may develop with heavy use. This study, conducted in central Taiwan, investigated whether betel quid chewers can exhibit overt orienting to selectively respond to the betel quid cues. Twenty-four male chewers' and 23 male nonchewers' eye movements to betel-quid-related pictures and matched pictures were assessed during a visual probe task. The eye movement index showed that betel quid chewers were more likely to initially direct their gaze to the betel quid cues, t(23) = 3.70, p < .01, d = .75, and spent more time, F(1, 23) = 4.58, p < .05, η₂ = .17, and were more fixated, F(1, 23) = 5.18, p < .05, η₂ = .18, on them. The visual probe index (response time) failed to detect the chewers' attentional bias. The current study provided the first eye movement evidence of betel quid chewers' attentional bias. The results demonstrated that the betel quid chewers (but not the nonchewers) were more likely to initially direct their gaze to the betel quid cues, and spent more time and were more fixated on them. These findings suggested that when attention is directly measured through the eye tracking technique, this methodology may be more sensitive to detecting attentional biases in betel quid chewers. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Method for targetless tracking subpixel in-plane movements.

PubMed

Espinosa, Julian; Perez, Jorge; Ferrer, Belen; Mas, David

2015-09-01

We present a targetless motion tracking method for detecting planar movements with subpixel accuracy. This method is based on the computation and tracking of the intersection of two nonparallel straight-line segments in the image of a moving object in a scene. The method is simple and easy to implement because no complex structures have to be detected. It has been tested and validated using a lab experiment consisting of a vibrating object that was recorded with a high-speed camera working at 1000 fps. We managed to track displacements with an accuracy of hundredths of pixel or even of thousandths of pixel in the case of tracking harmonic vibrations. The method is widely applicable because it can be used for distance measuring amplitude and frequency of vibrations with a vision system.

The Extended-Image Tracking Technique Based on the Maximum Likelihood Estimation

NASA Technical Reports Server (NTRS)

Tsou, Haiping; Yan, Tsun-Yee

2000-01-01

This paper describes an extended-image tracking technique based on the maximum likelihood estimation. The target image is assume to have a known profile covering more than one element of a focal plane detector array. It is assumed that the relative position between the imager and the target is changing with time and the received target image has each of its pixels disturbed by an independent additive white Gaussian noise. When a rotation-invariant movement between imager and target is considered, the maximum likelihood based image tracking technique described in this paper is a closed-loop structure capable of providing iterative update of the movement estimate by calculating the loop feedback signals from a weighted correlation between the currently received target image and the previously estimated reference image in the transform domain. The movement estimate is then used to direct the imager to closely follow the moving target. This image tracking technique has many potential applications, including free-space optical communications and astronomy where accurate and stabilized optical pointing is essential.

Multidirectional four-dimensional shape measurement system

NASA Astrophysics Data System (ADS)

Lenar, Janusz; Sitnik, Robert; Witkowski, Marcin

2012-03-01

Currently, a lot of different scanning techniques are used for 3D imaging of human body. Most of existing systems are based on static registration of internal structures using MRI or CT techniques as well as 3D scanning of outer surface of human body by laser triangulation or structured light methods. On the other hand there is an existing mature 4D method based on tracking in time the position of retro-reflective markers attached to human body. There are two main drawbacks of this solution: markers are attached to skin (no real skeleton movement is registered) and it gives (x, y, z, t) coordinates only in those points (not for the whole surface). In this paper we present a novel multidirectional structured light measurement system that is capable of measuring 3D shape of human body surface with frequency reaching 60Hz. The developed system consists of two spectrally separated and hardware-synchronized 4D measurement heads. The principle of the measurement is based on single frame analysis. Projected frame is composed from sine-modulated intensity pattern and a special stripe allowing absolute phase measurement. Several different geometrical set-ups will be proposed depending on type of movements that are to be registered.

A secure mobile crowdsensing (MCS) location tracker for elderly in smart city

NASA Astrophysics Data System (ADS)

Shien, Lau Khai; Singh, Manmeet Mahinderjit

2017-10-01

According to the UN's (United Nations) projection, Malaysia will achieve ageing population status by 2030. The challenge of the growing ageing population is health and social care services. As the population lives longer, the costs of institutional care rises and elderly who not able live independently in their own homes without caregivers. Moreover, it restricted their activity area, safety and freedom in their daily life. Hence, a tracking system is worthy for their caregivers to track their real-time location with efficient. Currently tracking and monitoring systems are unable to satisfy the needs of the community. Hence, Indoor-Outdoor Elderly Secure and Tracking care system (IOET) proposed to track and monitor elderly. This Mobile Crowdsensing type of system is using indoor and outdoor positioning system to locate elder which utilizes the RFID, NFC, biometric system and GPS aim to secure the safety of elderly within indoors and outdoors environment. A mobile application and web-based application to be designed for this system. This system able to real-time tracking by combining GPS and NFC for outdoor coverage where ideally in smart city. In indoor coverage, the system utilizes active RFID tracking elderly movement. The system will prompt caregiver wherever elderly movement or request by using the notification service which provided the real-time notify. Caregiver also can review the place that visited by elderly and trace back elderly movement.

A Visual Cortical Network for Deriving Phonological Information from Intelligible Lip Movements.

PubMed

Hauswald, Anne; Lithari, Chrysa; Collignon, Olivier; Leonardelli, Elisa; Weisz, Nathan

2018-05-07

Successful lip-reading requires a mapping from visual to phonological information [1]. Recently, visual and motor cortices have been implicated in tracking lip movements (e.g., [2]). It remains unclear, however, whether visuo-phonological mapping occurs already at the level of the visual cortex-that is, whether this structure tracks the acoustic signal in a functionally relevant manner. To elucidate this, we investigated how the cortex tracks (i.e., entrains to) absent acoustic speech signals carried by silent lip movements. Crucially, we contrasted the entrainment to unheard forward (intelligible) and backward (unintelligible) acoustic speech. We observed that the visual cortex exhibited stronger entrainment to the unheard forward acoustic speech envelope compared to the unheard backward acoustic speech envelope. Supporting the notion of a visuo-phonological mapping process, this forward-backward difference of occipital entrainment was not present for actually observed lip movements. Importantly, the respective occipital region received more top-down input, especially from left premotor, primary motor, and somatosensory regions and, to a lesser extent, also from posterior temporal cortex. Strikingly, across participants, the extent of top-down modulation of the visual cortex stemming from these regions partially correlated with the strength of entrainment to absent acoustic forward speech envelope, but not to present forward lip movements. Our findings demonstrate that a distributed cortical network, including key dorsal stream auditory regions [3-5], influences how the visual cortex shows sensitivity to the intelligibility of speech while tracking silent lip movements. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Characteristics of Handwriting of People With Cerebellar Ataxia: Three-Dimensional Movement Analysis of the Pen Tip, Finger, and Wrist.

PubMed

Fujisawa, Yuhki; Okajima, Yasutomo

2015-11-01

There are several functional tests for evaluating manual performance; however, quantitative manual tests for ataxia, especially those for evaluating handwriting, are limited. This study aimed to investigate the characteristics of cerebellar ataxia by analyzing handwriting, with a special emphasis on correlation between the movement of the pen tip and the movement of the finger or wrist. This was an observational study. Eleven people who were right-handed and had cerebellar ataxia and 17 people to serve as controls were recruited. The Scale for the Assessment and Rating of Ataxia was used to grade the severity of ataxia. Handwriting movements of both hands were analyzed. The time required for writing a character, the variability of individual handwriting, and the correlation between the movement of the pen tip and the movement of the finger or wrist were evaluated for participants with ataxia and control participants. The writing time was longer and the velocity profile and shape of the track of movement of the pen tip were more variable in participants with ataxia than in control participants. For participants with ataxia, the direction of movement of the pen tip deviated more from that of the finger or wrist, and the shape of the track of movement of the pen tip differed more from that of the finger or wrist. The severity of upper extremity ataxia measured with the Scale for the Assessment and Rating of Ataxia was mostly correlated with the variability parameters. Furthermore, it was correlated with the directional deviation of the trajectory of movement of the pen tip from that of the finger and with increased dissimilarity of the shapes of the tracks. The results may have been influenced by the scale and parameters used to measure movement. Ataxic handwriting with increased movement noise is characterized by irregular pen tip movements unconstrained by the finger or wrist. The severity of ataxia is correlated with these unconstrained movements. © 2015 American Physical Therapy Association.

Effects of damping head movement and facial expression in dyadic conversation using real–time facial expression tracking and synthesized avatars

PubMed Central

Boker, Steven M.; Cohn, Jeffrey F.; Theobald, Barry-John; Matthews, Iain; Brick, Timothy R.; Spies, Jeffrey R.

2009-01-01

When people speak with one another, they tend to adapt their head movements and facial expressions in response to each others' head movements and facial expressions. We present an experiment in which confederates' head movements and facial expressions were motion tracked during videoconference conversations, an avatar face was reconstructed in real time, and naive participants spoke with the avatar face. No naive participant guessed that the computer generated face was not video. Confederates' facial expressions, vocal inflections and head movements were attenuated at 1 min intervals in a fully crossed experimental design. Attenuated head movements led to increased head nods and lateral head turns, and attenuated facial expressions led to increased head nodding in both naive participants and confederates. Together, these results are consistent with a hypothesis that the dynamics of head movements in dyadicconversation include a shared equilibrium. Although both conversational partners were blind to the manipulation, when apparent head movement of one conversant was attenuated, both partners responded by increasing the velocity of their head movements. PMID:19884143

Ocean Surface Winds Drive Dynamics of Transoceanic Aerial Movements

PubMed Central

Felicísimo, Ángel M.; Muñoz, Jesús; González-Solis, Jacob

2008-01-01

Global wind patterns influence dispersal and migration processes of aerial organisms, propagules and particles, which ultimately could determine the dynamics of colonizations, invasions or spread of pathogens. However, studying how wind-mediated movements actually happen has been hampered so far by the lack of high resolution global wind data as well as the impossibility to track aerial movements. Using concurrent data on winds and actual pathways of a tracked seabird, here we show that oceanic winds define spatiotemporal pathways and barriers for large-scale aerial movements. We obtained wind data from NASA SeaWinds scatterometer to calculate wind cost (impedance) models reflecting the resistance to the aerial movement near the ocean surface. We also tracked the movements of a model organism, the Cory's shearwater (Calonectris diomedea), a pelagic bird known to perform long distance migrations. Cost models revealed that distant areas can be connected through “wind highways” that do not match the shortest great circle routes. Bird routes closely followed the low-cost “wind-highways” linking breeding and wintering areas. In addition, we found that a potential barrier, the near surface westerlies in the Atlantic sector of the Intertropical Convergence Zone (ITCZ), temporally hindered meridional trans-equatorial movements. Once the westerlies vanished, birds crossed the ITCZ to their winter quarters. This study provides a novel approach to investigate wind-mediated movements in oceanic environments and shows that large-scale migration and dispersal processes over the oceans can be largely driven by spatiotemporal wind patterns. PMID:18698354

Ocean surface winds drive dynamics of transoceanic aerial movements.

PubMed

Felicísimo, Angel M; Muñoz, Jesús; González-Solis, Jacob

2008-08-13

Global wind patterns influence dispersal and migration processes of aerial organisms, propagules and particles, which ultimately could determine the dynamics of colonizations, invasions or spread of pathogens. However, studying how wind-mediated movements actually happen has been hampered so far by the lack of high resolution global wind data as well as the impossibility to track aerial movements. Using concurrent data on winds and actual pathways of a tracked seabird, here we show that oceanic winds define spatiotemporal pathways and barriers for large-scale aerial movements. We obtained wind data from NASA SeaWinds scatterometer to calculate wind cost (impedance) models reflecting the resistance to the aerial movement near the ocean surface. We also tracked the movements of a model organism, the Cory's shearwater (Calonectris diomedea), a pelagic bird known to perform long distance migrations. Cost models revealed that distant areas can be connected through "wind highways" that do not match the shortest great circle routes. Bird routes closely followed the low-cost "wind-highways" linking breeding and wintering areas. In addition, we found that a potential barrier, the near surface westerlies in the Atlantic sector of the Intertropical Convergence Zone (ITCZ), temporally hindered meridional trans-equatorial movements. Once the westerlies vanished, birds crossed the ITCZ to their winter quarters. This study provides a novel approach to investigate wind-mediated movements in oceanic environments and shows that large-scale migration and dispersal processes over the oceans can be largely driven by spatiotemporal wind patterns.

Robot Tracer with Visual Camera

NASA Astrophysics Data System (ADS)

Jabbar Lubis, Abdul; Dwi Lestari, Yuyun; Dafitri, Haida; Azanuddin

2017-12-01

Robot is a versatile tool that can function replace human work function. The robot is a device that can be reprogrammed according to user needs. The use of wireless networks for remote monitoring needs can be utilized to build a robot that can be monitored movement and can be monitored using blueprints and he can track the path chosen robot. This process is sent using a wireless network. For visual robot using high resolution cameras to facilitate the operator to control the robot and see the surrounding circumstances.

In-vivo study of blood flow in capillaries using μPIV method

NASA Astrophysics Data System (ADS)

Kurochkin, Maxim A.; Fedosov, Ivan V.; Tuchin, Valery V.

2014-01-01

A digital optical system for intravital capillaroscopy has been developed. It implements the particle image velocimetry (PIV) based approach for measurements of red blood cells velocity in individual capillary of human nailfold. We propose to use a digital real time stabilization technique for compensation of impact of involuntary movements of a finger on results of measurements. Image stabilization algorithm is based on correlation of feature tracking. The efficiency of designed image stabilization algorithm was experimentally demonstrated.

30 CFR 56.9102 - Movement of independently operating rail equipment.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Movement of independently operating rail... MINES Loading, Hauling, and Dumping Traffic Safety § 56.9102 Movement of independently operating rail equipment. Movement of two or more pieces of rail equipment operating independently on the same track shall...

Development of real-time motion capture system for 3D on-line games linked with virtual character

NASA Astrophysics Data System (ADS)

Kim, Jong Hyeong; Ryu, Young Kee; Cho, Hyung Suck

2004-10-01

Motion tracking method is being issued as essential part of the entertainment, medical, sports, education and industry with the development of 3-D virtual reality. Virtual human character in the digital animation and game application has been controlled by interfacing devices; mouse, joysticks, midi-slider, and so on. Those devices could not enable virtual human character to move smoothly and naturally. Furthermore, high-end human motion capture systems in commercial market are expensive and complicated. In this paper, we proposed a practical and fast motion capturing system consisting of optic sensors, and linked the data with 3-D game character with real time. The prototype experiment setup is successfully applied to a boxing game which requires very fast movement of human character.

Eye movements reveal epistemic curiosity in human observers.

PubMed

Baranes, Adrien; Oudeyer, Pierre-Yves; Gottlieb, Jacqueline

2015-12-01

Saccadic (rapid) eye movements are primary means by which humans and non-human primates sample visual information. However, while saccadic decisions are intensively investigated in instrumental contexts where saccades guide subsequent actions, it is largely unknown how they may be influenced by curiosity - the intrinsic desire to learn. While saccades are sensitive to visual novelty and visual surprise, no study has examined their relation to epistemic curiosity - interest in symbolic, semantic information. To investigate this question, we tracked the eye movements of human observers while they read trivia questions and, after a brief delay, were visually given the answer. We show that higher curiosity was associated with earlier anticipatory orienting of gaze toward the answer location without changes in other metrics of saccades or fixations, and that these influences were distinct from those produced by variations in confidence and surprise. Across subjects, the enhancement of anticipatory gaze was correlated with measures of trait curiosity from personality questionnaires. Finally, a machine learning algorithm could predict curiosity in a cross-subject manner, relying primarily on statistical features of the gaze position before the answer onset and independently of covariations in confidence or surprise, suggesting potential practical applications for educational technologies, recommender systems and research in cognitive sciences. With this article, we provide full access to the annotated database allowing readers to reproduce the results. Epistemic curiosity produces specific effects on oculomotor anticipation that can be used to read out curiosity states. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Web Camera Based Eye Tracking to Assess Visual Memory on a Visual Paired Comparison Task.

PubMed

Bott, Nicholas T; Lange, Alex; Rentz, Dorene; Buffalo, Elizabeth; Clopton, Paul; Zola, Stuart

2017-01-01

Background: Web cameras are increasingly part of the standard hardware of most smart devices. Eye movements can often provide a noninvasive "window on the brain," and the recording of eye movements using web cameras is a burgeoning area of research. Objective: This study investigated a novel methodology for administering a visual paired comparison (VPC) decisional task using a web camera.To further assess this method, we examined the correlation between a standard eye-tracking camera automated scoring procedure [obtaining images at 60 frames per second (FPS)] and a manually scored procedure using a built-in laptop web camera (obtaining images at 3 FPS). Methods: This was an observational study of 54 clinically normal older adults.Subjects completed three in-clinic visits with simultaneous recording of eye movements on a VPC decision task by a standard eye tracker camera and a built-in laptop-based web camera. Inter-rater reliability was analyzed using Siegel and Castellan's kappa formula. Pearson correlations were used to investigate the correlation between VPC performance using a standard eye tracker camera and a built-in web camera. Results: Strong associations were observed on VPC mean novelty preference score between the 60 FPS eye tracker and 3 FPS built-in web camera at each of the three visits ( r = 0.88-0.92). Inter-rater agreement of web camera scoring at each time point was high (κ = 0.81-0.88). There were strong relationships on VPC mean novelty preference score between 10, 5, and 3 FPS training sets ( r = 0.88-0.94). Significantly fewer data quality issues were encountered using the built-in web camera. Conclusions: Human scoring of a VPC decisional task using a built-in laptop web camera correlated strongly with automated scoring of the same task using a standard high frame rate eye tracker camera.While this method is not suitable for eye tracking paradigms requiring the collection and analysis of fine-grained metrics, such as fixation points, built-in web cameras are a standard feature of most smart devices (e.g., laptops, tablets, smart phones) and can be effectively employed to track eye movements on decisional tasks with high accuracy and minimal cost.

Speckle tracking as a method to measure hemidiaphragm excursion.

PubMed

Goutman, Stephen A; Hamilton, James D; Swihart, Blake; Foerster, Bradley; Feldman, Eva L; Rubin, Jonathan M

2017-01-01

Diaphragm excursion measured via ultrasound may be an important imaging outcome measure of respiratory function. We developed a new method for measuring diaphragm movement and compared it to the more traditional M-mode method. Ultrasound images of the right and left hemidiaphragms were collected to compare speckle tracking and M-mode measurements of diaphragm excursion. Speckle tracking was performed using EchoInsight (Epsilon Imaging, Ann Arbor, Michigan). Six healthy subjects without a history of pulmonary diseases were included in this proof-of-concept study. Speckle tracking of the diaphragm is technically possible. Unlike M-mode, speckle tracking carries the advantage of reliable visualization and measurement of the left hemidiaphragm. Speckle tracking accounted for diaphragm movement simultaneously in the cephalocaudad and mediolateral directions, unlike M-mode, which is 1-dimensional. Diaphragm speckle tracking may represent a novel, more robust method for measuring diaphragm excursion, especially for the left hemidiaphragm. Muscle Nerve 55: 125-127, 2017. © 2016 Wiley Periodicals, Inc.

Accuracy of tracking forest machines with GPS

Treesearch

M.W. Veal; S.E. Taylor; T.P. McDonald; D.K. McLemore; M.R. Dunn

2001-01-01

This paper describes the results of a study that measured the accuracy of using GPS to track movement of forest machines. Two different commercially available GPS receivers (Trimble ProXR and GeoExplorer II) were used to track\\r\

When Art Moves the Eyes: A Behavioral and Eye-Tracking Study

PubMed Central

Massaro, Davide; Savazzi, Federica; Di Dio, Cinzia; Freedberg, David; Gallese, Vittorio; Gilli, Gabriella; Marchetti, Antonella

2012-01-01

The aim of this study was to investigate, using eye-tracking technique, the influence of bottom-up and top-down processes on visual behavior while subjects, naïve to art criticism, were presented with representational paintings. Forty-two subjects viewed color and black and white paintings (Color) categorized as dynamic or static (Dynamism) (bottom-up processes). Half of the images represented natural environments and half human subjects (Content); all stimuli were displayed under aesthetic and movement judgment conditions (Task) (top-down processes). Results on gazing behavior showed that content-related top-down processes prevailed over low-level visually-driven bottom-up processes when a human subject is represented in the painting. On the contrary, bottom-up processes, mediated by low-level visual features, particularly affected gazing behavior when looking at nature-content images. We discuss our results proposing a reconsideration of the definition of content-related top-down processes in accordance with the concept of embodied simulation in art perception. PMID:22624007

Eye tracking uncovered great apes' ability to anticipate that other individuals will act according to false beliefs.

PubMed

Kano, Fumihiro; Krupenye, Christopher; Hirata, Satoshi; Call, Josep

2017-01-01

Using a novel eye-tracking test, we recently showed that great apes anticipate that other individuals will act according to false beliefs. This finding suggests that, like humans, great apes understand others' false beliefs, at least in an implicit way. One key question raised by our study is why apes have passed our tests but not previous ones. In this article, we consider this question by detailing the development of our task. We considered 3 major differences in our task compared with the previous ones. First, we monitored apes' eye movements, and specifically their anticipatory looks, to measure their predictions about how agents will behave. Second, we adapted our design from an anticipatory-looking false belief test originally developed for human infants. Third, we developed novel test scenarios that were specifically designed to capture the attention of our ape participants. We then discuss how each difference may help explain differences in performance on our task and previous ones, and finally propose some directions for future studies.

Wireless physiological monitoring and ocular tracking: 3D calibration in a fully-immersive virtual health care environment.

PubMed

Zhang, Lelin; Chi, Yu Mike; Edelstein, Eve; Schulze, Jurgen; Gramann, Klaus; Velasquez, Alvaro; Cauwenberghs, Gert; Macagno, Eduardo

2010-01-01

Wireless physiological/neurological monitoring in virtual reality (VR) offers a unique opportunity for unobtrusively quantifying human responses to precisely controlled and readily modulated VR representations of health care environments. Here we present such a wireless, light-weight head-mounted system for measuring electrooculogram (EOG) and electroencephalogram (EEG) activity in human subjects interacting with and navigating in the Calit2 StarCAVE, a five-sided immersive 3-D visualization VR environment. The system can be easily expanded to include other measurements, such as cardiac activity and galvanic skin responses. We demonstrate the capacity of the system to track focus of gaze in 3-D and report a novel calibration procedure for estimating eye movements from responses to the presentation of a set of dynamic visual cues in the StarCAVE. We discuss cyber and clinical applications that include a 3-D cursor for visual navigation in VR interactive environments, and the monitoring of neurological and ocular dysfunction in vision/attention disorders.

When art moves the eyes: a behavioral and eye-tracking study.

PubMed

Massaro, Davide; Savazzi, Federica; Di Dio, Cinzia; Freedberg, David; Gallese, Vittorio; Gilli, Gabriella; Marchetti, Antonella

2012-01-01

The aim of this study was to investigate, using eye-tracking technique, the influence of bottom-up and top-down processes on visual behavior while subjects, naïve to art criticism, were presented with representational paintings. Forty-two subjects viewed color and black and white paintings (Color) categorized as dynamic or static (Dynamism) (bottom-up processes). Half of the images represented natural environments and half human subjects (Content); all stimuli were displayed under aesthetic and movement judgment conditions (Task) (top-down processes). Results on gazing behavior showed that content-related top-down processes prevailed over low-level visually-driven bottom-up processes when a human subject is represented in the painting. On the contrary, bottom-up processes, mediated by low-level visual features, particularly affected gazing behavior when looking at nature-content images. We discuss our results proposing a reconsideration of the definition of content-related top-down processes in accordance with the concept of embodied simulation in art perception.

Thermal activation energy for bidirectional movement of actin along bipolar tracks of myosin filaments.

PubMed

Okubo, Hiroyuki; Iwai, Masanori; Iwai, Sosuke; Chaen, Shigeru

2010-05-28

Previous in vitro motility assays using bipolar myosin thick filaments demonstrated that actin filaments were capable of moving in both directions along the myosin filament tracks. The movements; however, were slower in the direction leading away from the central bare zone than towards it. To understand the mechanism underlying these different direction-dependent motilities, we have examined the effects of temperature on the velocities of the bidirectional movements along reconstituted myosin filaments. Activation energies of the movements were determined by Arrhenius plots at high and low concentrations of ATP. As a result, the thermal activation energy of the movement away from the central bare zone was significantly higher than that of the movement toward the zone. Given that the backward movement away from the central bare zone would cause the myosin heads to be constrained and the stiffness of the cross-bridges to increase, these results suggest that elastic energy required for the cross-bridge transition is supplied by thermal fluctuations. Copyright (c) 2010 Elsevier Inc. All rights reserved.

Temporal eye movement strategies during naturalistic viewing

PubMed Central

Wang, Helena X.; Freeman, Jeremy; Merriam, Elisha P.; Hasson, Uri; Heeger, David J.

2011-01-01

The deployment of eye movements to complex spatiotemporal stimuli likely involves a variety of cognitive factors. However, eye movements to movies are surprisingly reliable both within and across observers. We exploited and manipulated that reliability to characterize observers’ temporal viewing strategies. Introducing cuts and scrambling the temporal order of the resulting clips systematically changed eye movement reliability. We developed a computational model that exhibited this behavior and provided an excellent fit to the measured eye movement reliability. The model assumed that observers searched for, found, and tracked a point-of-interest, and that this process reset when there was a cut. The model did not require that eye movements depend on temporal context in any other way, and it managed to describe eye movements consistently across different observers and two movie sequences. Thus, we found no evidence for the integration of information over long time scales (greater than a second). The results are consistent with the idea that observers employ a simple tracking strategy even while viewing complex, engaging naturalistic stimuli. PMID:22262911

A Novel Wearable Forehead EOG Measurement System for Human Computer Interfaces

PubMed Central

Heo, Jeong; Yoon, Heenam; Park, Kwang Suk

2017-01-01

Amyotrophic lateral sclerosis (ALS) patients whose voluntary muscles are paralyzed commonly communicate with the outside world using eye movement. There have been many efforts to support this method of communication by tracking or detecting eye movement. An electrooculogram (EOG), an electro-physiological signal, is generated by eye movements and can be measured with electrodes placed around the eye. In this study, we proposed a new practical electrode position on the forehead to measure EOG signals, and we developed a wearable forehead EOG measurement system for use in Human Computer/Machine interfaces (HCIs/HMIs). Four electrodes, including the ground electrode, were placed on the forehead. The two channels were arranged vertically and horizontally, sharing a positive electrode. Additionally, a real-time eye movement classification algorithm was developed based on the characteristics of the forehead EOG. Three applications were employed to evaluate the proposed system: a virtual keyboard using a modified Bremen BCI speller and an automatic sequential row-column scanner, and a drivable power wheelchair. The mean typing speeds of the modified Bremen brain–computer interface (BCI) speller and automatic row-column scanner were 10.81 and 7.74 letters per minute, and the mean classification accuracies were 91.25% and 95.12%, respectively. In the power wheelchair demonstration, the user drove the wheelchair through an 8-shape course without collision with obstacles. PMID:28644398

A Novel Wearable Forehead EOG Measurement System for Human Computer Interfaces.

PubMed

Heo, Jeong; Yoon, Heenam; Park, Kwang Suk

2017-06-23

Amyotrophic lateral sclerosis (ALS) patients whose voluntary muscles are paralyzed commonly communicate with the outside world using eye movement. There have been many efforts to support this method of communication by tracking or detecting eye movement. An electrooculogram (EOG), an electro-physiological signal, is generated by eye movements and can be measured with electrodes placed around the eye. In this study, we proposed a new practical electrode position on the forehead to measure EOG signals, and we developed a wearable forehead EOG measurement system for use in Human Computer/Machine interfaces (HCIs/HMIs). Four electrodes, including the ground electrode, were placed on the forehead. The two channels were arranged vertically and horizontally, sharing a positive electrode. Additionally, a real-time eye movement classification algorithm was developed based on the characteristics of the forehead EOG. Three applications were employed to evaluate the proposed system: a virtual keyboard using a modified Bremen BCI speller and an automatic sequential row-column scanner, and a drivable power wheelchair. The mean typing speeds of the modified Bremen brain-computer interface (BCI) speller and automatic row-column scanner were 10.81 and 7.74 letters per minute, and the mean classification accuracies were 91.25% and 95.12%, respectively. In the power wheelchair demonstration, the user drove the wheelchair through an 8-shape course without collision with obstacles.

Molecular motors that digest their track to rectify Brownian motion: processive movement of exonuclease enzymes.

PubMed

Xie, Ping

2009-09-16

A general model is presented for the processive movement of molecular motors such as λ-exonuclease, RecJ and exonuclease I that use digestion of a DNA track to rectify Brownian motion along this track. Using this model, the translocation dynamics of these molecular motors is studied. The sequence-dependent pausing of λ-exonuclease, which results from a site-specific high affinity DNA interaction, is also studied. The theoretical results are consistent with available experimental data. Moreover, the model is used to predict the lifetime distribution and force dependence of these paused states.

Satellite Tracking of Manta Rays Highlights Challenges to Their Conservation

PubMed Central

Graham, Rachel T.; Witt, Matthew J.; Castellanos, Dan W.; Remolina, Francisco; Maxwell, Sara; Godley, Brendan J.; Hawkes, Lucy A.

2012-01-01

We describe the real-time movements of the last of the marine mega-vertebrate taxa to be satellite tracked – the giant manta ray (or devil fish, Manta birostris), the world's largest ray at over 6 m disc width. Almost nothing is known about manta ray movements and their environmental preferences, making them one of the least understood of the marine mega-vertebrates. Red listed by the International Union for the Conservation of Nature as ‘Vulnerable’ to extinction, manta rays are known to be subject to direct and incidental capture and some populations are declining. Satellite-tracked manta rays associated with seasonal upwelling events and thermal fronts off the Yucatan peninsula, Mexico, and made short-range shuttling movements, foraging along and between them. The majority of locations were received from waters shallower than 50 m deep, representing thermally dynamic and productive waters. Manta rays remained in the Mexican Exclusive Economic Zone for the duration of tracking but only 12% of tracking locations were received from within Marine Protected Areas (MPAs). Our results on the spatio-temporal distribution of these enigmatic rays highlight opportunities and challenges to management efforts. PMID:22590622

A laser-based eye-tracking system.

PubMed

Irie, Kenji; Wilson, Bruce A; Jones, Richard D; Bones, Philip J; Anderson, Tim J

2002-11-01

This paper reports on the development of a new eye-tracking system for noninvasive recording of eye movements. The eye tracker uses a flying-spot laser to selectively image landmarks on the eye and, subsequently, measure horizontal, vertical, and torsional eye movements. Considerable work was required to overcome the adverse effects of specular reflection of the flying-spot from the surface of the eye onto the sensing elements of the eye tracker. These effects have been largely overcome, and the eye-tracker has been used to document eye movement abnormalities, such as abnormal torsional pulsion of saccades, in the clinical setting.

Intelligent Paging Based Mobile User Tracking Using Fuzzy Logic

NASA Astrophysics Data System (ADS)

Saha, Sajal; Dutta, Raju; Debnath, Soumen; Mukhopadhyay, Asish K.

2010-11-01

In general, a mobile user travels in a predefined path that depends mostly on the user's characteristics. Thus, tracking the locations of a mobile user is one of the challenges for location management. In this paper, we introduce a movement pattern learning strategy system to track the user's movements using adaptive fuzzy logic. Our fuzzy inference system extracts patterns from the historical data record of the cell numbers along with the date and time stamp of the users occupying the cell. Implementation of this strategy has been evaluated with the real time user data which proves the efficiency and accuracy of the model. This mechanism not only reduces user location tracking costs, but also significantly decreases the call-loss rates and average paging delays.

RATT: RFID Assisted Tracking Tile. Preliminary results.

PubMed

Quinones, Dario R; Cuevas, Aaron; Cambra, Javier; Canals, Santiago; Moratal, David

2017-07-01

Behavior is one of the most important aspects of animal life. This behavior depends on the link between animals, their nervous systems and their environment. In order to study the behavior of laboratory animals several tools are needed, but a tracking tool is essential to perform a thorough behavioral study. Currently, several visual tracking tools are available. However, they have some drawbacks. For instance, when an animal is inside a cave, or is close to other animals, the tracking cameras cannot always detect the location or movement of this animal. This paper presents RFID Assisted Tracking Tile (RATT), a tracking system based on passive Radio Frequency Identification (RFID) technology in high frequency band according to ISO/IEC 15693. The RATT system is composed of electronic tiles that have nine active RFID antennas attached; in addition, it contains several overlapping passive coils to improve the magnetic field characteristics. Using several tiles, a large surface can be built on which the animals can move, allowing identification and tracking of their movements. This system, that could also be combined with a visual tracking system, paves the way for complete behavioral studies.

Resource tracking within and across continents in long-distance bird migrants.

PubMed

Thorup, Kasper; Tøttrup, Anders P; Willemoes, Mikkel; Klaassen, Raymond H G; Strandberg, Roine; Vega, Marta Lomas; Dasari, Hari P; Araújo, Miguel B; Wikelski, Martin; Rahbek, Carsten

2017-01-01

Migratory birds track seasonal resources across and between continents. We propose a general strategy of tracking the broad seasonal abundance of resources throughout the annual cycle in the longest-distance migrating land birds as an alternative to tracking a certain climatic niche or shorter-term resource surplus occurring, for example, during spring foliation. Whether and how this is possible for complex annual spatiotemporal schedules is not known. New tracking technology enables unprecedented spatial and temporal mapping of long-distance movement of birds. We show that three Palearctic-African species track vegetation greenness throughout their annual cycle, adjusting the timing and direction of migratory movements with seasonal changes in resource availability over Europe and Africa. Common cuckoos maximize the vegetation greenness, whereas red-backed shrikes and thrush nightingales track seasonal surplus in greenness. Our results demonstrate that the longest-distance migrants move between consecutive staging areas even within the wintering region in Africa to match seasonal variation in regional climate. End-of-century climate projections indicate that optimizing greenness would be possible but that vegetation surplus might be more difficult to track in the future.

Resource tracking within and across continents in long-distance bird migrants

PubMed Central

Thorup, Kasper; Tøttrup, Anders P.; Willemoes, Mikkel; Klaassen, Raymond H. G.; Strandberg, Roine; Vega, Marta Lomas; Dasari, Hari P.; Araújo, Miguel B.; Wikelski, Martin; Rahbek, Carsten

2017-01-01

Migratory birds track seasonal resources across and between continents. We propose a general strategy of tracking the broad seasonal abundance of resources throughout the annual cycle in the longest-distance migrating land birds as an alternative to tracking a certain climatic niche or shorter-term resource surplus occurring, for example, during spring foliation. Whether and how this is possible for complex annual spatiotemporal schedules is not known. New tracking technology enables unprecedented spatial and temporal mapping of long-distance movement of birds. We show that three Palearctic-African species track vegetation greenness throughout their annual cycle, adjusting the timing and direction of migratory movements with seasonal changes in resource availability over Europe and Africa. Common cuckoos maximize the vegetation greenness, whereas red-backed shrikes and thrush nightingales track seasonal surplus in greenness. Our results demonstrate that the longest-distance migrants move between consecutive staging areas even within the wintering region in Africa to match seasonal variation in regional climate. End-of-century climate projections indicate that optimizing greenness would be possible but that vegetation surplus might be more difficult to track in the future. PMID:28070557

Using sutures to attach miniature tracking tags to small bats for multimonth movement and behavioral studies

USGS Publications Warehouse

Castle, Kevin T.; Weller, Theodore J.; Cryan, Paul M.; Hein, Cris D.; Schirmacher, Michael R.

2015-01-01

1. Determining the detailed movements of individual animals often requires them to carry tracking devices, but tracking broad-scale movement of small bats (< 30g) has been limited by transmitter technology and long-term attachment methods. This limitation inhibits our understanding of bat dispersal and migration, particularly in the context of emerging conservation issues like fatalities at wind turbines and diseases. 2. We tested a novel method of attaching lightweight global positioning system (GPS) tags and geolocating data loggers to small bats. We used monofilament, synthetic, absorbable sutures to secure GPS tags and data loggers to the skin of anesthetized big brown bats (Eptesicus fuscus) in Colorado and hoary bats (Lasiurus cinereus) in California. 3. GPS tags and data loggers were sutured to 17 bats in this study. Three tagged bats were recaptured seven months after initial deployment, with tags still attached; none of these bats showed ill effects from the tag. No severe injuries were apparent upon recapture of 6 additional bats that carried tags up to 26 days after attachment, however one of the bats exhibited skin chafing. 4. Use of absorbable sutures to affix small tracking devices seems to be a safe, effective method for studying movements of bats over multiple months, although additional testing is warranted. This new attachment method has the potential to quickly advance our understanding of small bats, particularly as more-sophisticated miniature tracking devices (e.g., satellite tags) become available.

Using sutures to attach miniature tracking tags to small bats for multimonth movement and behavioral studies.

PubMed

Castle, Kevin T; Weller, Theodore J; Cryan, Paul M; Hein, Cris D; Schirmacher, Michael R

2015-07-01

Determining the detailed movements of individual animals often requires them to carry tracking devices, but tracking broad-scale movement of small bats (<30 g) has been limited by transmitter technology and long-term attachment methods. This limitation inhibits our understanding of bat dispersal and migration, particularly in the context of emerging conservation issues such as fatalities at wind turbines and diseases. We tested a novel method of attaching lightweight global positioning system (GPS) tags and geolocating data loggers to small bats. We used monofilament, synthetic, absorbable sutures to secure GPS tags and data loggers to the skin of anesthetized big brown bats (Eptesicus fuscus) in Colorado and hoary bats (Lasiurus cinereus) in California. GPS tags and data loggers were sutured to 17 bats in this study. Three tagged bats were recaptured 7 months after initial deployment, with tags still attached; none of these bats showed ill effects from the tag. No severe injuries were apparent upon recapture of 6 additional bats that carried tags up to 26 days after attachment; however, one of the bats exhibited skin chafing. Use of absorbable sutures to affix small tracking devices seems to be a safe, effective method for studying movements of bats over multiple months, although additional testing is warranted. This new attachment method has the potential to quickly advance our understanding of small bats, particularly as more sophisticated miniature tracking devices (e.g., satellite tags) become available.

Sustained disruption of narwhal habitat use and behavior in the presence of Arctic killer whales

PubMed Central

Breed, Greg A.; Matthews, Cory J. D.; Marcoux, Marianne; Higdon, Jeff W.; LeBlanc, Bernard; Petersen, Stephen D.; Orr, Jack; Reinhart, Natalie R.; Ferguson, Steven H.

2017-01-01

Although predators influence behavior of prey, analyses of electronic tracking data in marine environments rarely consider how predators affect the behavior of tracked animals. We collected an unprecedented dataset by synchronously tracking predator (killer whales, N = 1; representing a family group) and prey (narwhal, N = 7) via satellite telemetry in Admiralty Inlet, a large fjord in the Eastern Canadian Arctic. Analyzing the movement data with a switching-state space model and a series of mixed effects models, we show that the presence of killer whales strongly alters the behavior and distribution of narwhal. When killer whales were present (within about 100 km), narwhal moved closer to shore, where they were presumably less vulnerable. Under predation threat, narwhal movement patterns were more likely to be transiting, whereas in the absence of threat, more likely resident. Effects extended beyond discrete predatory events and persisted steadily for 10 d, the duration that killer whales remained in Admiralty Inlet. Our findings have two key consequences. First, given current reductions in sea ice and increases in Arctic killer whale sightings, killer whales have the potential to reshape Arctic marine mammal distributions and behavior. Second and of more general importance, predators have the potential to strongly affect movement behavior of tracked marine animals. Understanding predator effects may be as or more important than relating movement behavior to resource distribution or bottom-up drivers traditionally included in analyses of marine animal tracking data. PMID:28223481

Sustained disruption of narwhal habitat use and behavior in the presence of Arctic killer whales.

PubMed

Breed, Greg A; Matthews, Cory J D; Marcoux, Marianne; Higdon, Jeff W; LeBlanc, Bernard; Petersen, Stephen D; Orr, Jack; Reinhart, Natalie R; Ferguson, Steven H

2017-03-07

Although predators influence behavior of prey, analyses of electronic tracking data in marine environments rarely consider how predators affect the behavior of tracked animals. We collected an unprecedented dataset by synchronously tracking predator (killer whales, [Formula: see text] = 1; representing a family group) and prey (narwhal, [Formula: see text] = 7) via satellite telemetry in Admiralty Inlet, a large fjord in the Eastern Canadian Arctic. Analyzing the movement data with a switching-state space model and a series of mixed effects models, we show that the presence of killer whales strongly alters the behavior and distribution of narwhal. When killer whales were present (within about 100 km), narwhal moved closer to shore, where they were presumably less vulnerable. Under predation threat, narwhal movement patterns were more likely to be transiting, whereas in the absence of threat, more likely resident. Effects extended beyond discrete predatory events and persisted steadily for 10 d, the duration that killer whales remained in Admiralty Inlet. Our findings have two key consequences. First, given current reductions in sea ice and increases in Arctic killer whale sightings, killer whales have the potential to reshape Arctic marine mammal distributions and behavior. Second and of more general importance, predators have the potential to strongly affect movement behavior of tracked marine animals. Understanding predator effects may be as or more important than relating movement behavior to resource distribution or bottom-up drivers traditionally included in analyses of marine animal tracking data.

A Model of Loggerhead Sea Turtle (Caretta caretta) Habitat and Movement in the Oceanic North Pacific

PubMed Central

Abecassis, Melanie; Senina, Inna; Lehodey, Patrick; Gaspar, Philippe; Parker, Denise; Balazs, George; Polovina, Jeffrey

2013-01-01

Habitat preferences for juvenile loggerhead turtles in the North Pacific were investigated with data from two several-year long tagging programs, using 224 satellite transmitters deployed on wild and captive-reared turtles. Animals ranged between 23 and 81 cm in straight carapace length. Tracks were used to investigate changes in temperature preferences and speed of the animals with size. Average sea surface temperatures along the tracks ranged from 18 to 23 °C. Bigger turtles generally experienced larger temperature ranges and were encountered in warmer surface waters. Seasonal differences between small and big turtles suggest that the larger ones dive deeper than the mixed layer and subsequently target warmer surface waters to rewarm. Average swimming speeds were under 1 km/h and increased with size for turtles bigger than 30 cm. However, when expressed in body lengths per second (bl s−1), smaller turtles showed much higher swimming speeds (>1 bl s −1) than bigger ones (0.5 bl s−1). Temperature and speed values at size estimated from the tracks were used to parameterize a habitat-based Eulerian model to predict areas of highest probability of presence in the North Pacific. The model-generated habitat index generally matched the tracks closely, capturing the north-south movements of tracked animals, but the model failed to replicate observed east-west movements, suggesting temperature and foraging preferences are not the only factors driving large-scale loggerhead movements. Model outputs could inform potential bycatch reduction strategies. PMID:24039901

Underwater behavior of sperm whales off Kaikoura, New Zealand, as revealed by a three-dimensional hydrophone array.

PubMed

Miller, Brian; Dawson, Stephen; Vennell, Ross

2013-10-01

Observations are presented of the vocal behavior and three dimensional (3D) underwater movements of sperm whales measured with a passive acoustic array off the coast of Kaikoura, New Zealand. Visual observations and vocal behaviors of whales were used to divide dive tracks into different phases, and depths and movements of whales are reported for each of these phases. Diving depths and movement information from 75 3D tracks of whales in Kaikoura are compared to one and two dimensional tracks of whales studied in other oceans. While diving, whales in Kaikoura had a mean swimming speed of 1.57 m/s, and, on average, dived to a depth of 427 m (SD = 117 m), spending most of their time at depths between 300 and 600 m. Creak vocalizations, assumed to be the prey capture phase of echolocation, occurred throughout the water column from sea surface to sea floor, but most occurred at depths of 400-550 m. Three dimensional measurement of tracking revealed several different "foraging" strategies, including active chasing of prey, lining up slow-moving or unsuspecting prey, and foraging on demersal or benthic prey. These movements provide the first 3D descriptions underwater behavior of whales at Kaikoura.

Eye-movements and Voice as Interface Modalities to Computer Systems

NASA Astrophysics Data System (ADS)

Farid, Mohsen M.; Murtagh, Fionn D.

2003-03-01

We investigate the visual and vocal modalities of interaction with computer systems. We focus our attention on the integration of visual and vocal interface as possible replacement and/or additional modalities to enhance human-computer interaction. We present a new framework for employing eye gaze as a modality of interface. While voice commands, as means of interaction with computers, have been around for a number of years, integration of both the vocal interface and the visual interface, in terms of detecting user's eye movements through an eye-tracking device, is novel and promises to open the horizons for new applications where a hand-mouse interface provides little or no apparent support to the task to be accomplished. We present an array of applications to illustrate the new framework and eye-voice integration.

Quantitative evaluation of age-related decline in control of preprogramed movement

PubMed Central

Lee, Jongho; Kodama, Mitsuhiko; Kakei, Shinji; Masakado, Yoshihisa

2017-01-01

In this paper, we examined the age-related changes in control of preprogramed movement, with emphasis on its accuracy. Forty-nine healthy subjects participated in this study, and were divided into three groups depending on their ages: the young group (20–39 years) (n = 16), the middle-age group (40–59 years) (n = 16), and the elderly group (60–79 years) (n = 17). We asked the subjects to perform step-tracking movements of the wrist joint with a manipulandum, and recorded the movements. We evaluated the accuracy of control of preprogramed movement in the three groups in terms of the primary submovement, which was identified as the first segment of the step-tracking movement based on the bell-shaped velocity profile, and calculated the distance between the end position of the primary submovement and the target (i.e. error). The error in the young group was found to be significantly smaller than that in the middle-age and elderly groups, i.e., the error was larger for the higher age groups. These results suggest that young subjects have better control of preprogramed movement than middle-age or elderly subjects. Finally, we examined the temporal property of the primary submovement and its age-related changes. The duration of the primary submovement tended to be longer for the aged groups, although significance was reached only for the elderly group. In particular, the ratio of the duration of the primary submovement to total movement time tended to be lower for the aged groups, suggesting that the proportion of additional movements that are required to compensate for the incomplete control in the preprogramed movement, which are under feedback control, was higher for the aged groups. Consequently, our results indicate that the distance between the end point of the primary submovement and the target center (i.e. error) in the step-tracking movement is a useful parameter to evaluate the age-related changes in control of preprogramed movement. PMID:29186168

Quantitative evaluation of age-related decline in control of preprogramed movement.

PubMed

Shimoda, Naoshi; Lee, Jongho; Kodama, Mitsuhiko; Kakei, Shinji; Masakado, Yoshihisa

2017-01-01

In this paper, we examined the age-related changes in control of preprogramed movement, with emphasis on its accuracy. Forty-nine healthy subjects participated in this study, and were divided into three groups depending on their ages: the young group (20-39 years) (n = 16), the middle-age group (40-59 years) (n = 16), and the elderly group (60-79 years) (n = 17). We asked the subjects to perform step-tracking movements of the wrist joint with a manipulandum, and recorded the movements. We evaluated the accuracy of control of preprogramed movement in the three groups in terms of the primary submovement, which was identified as the first segment of the step-tracking movement based on the bell-shaped velocity profile, and calculated the distance between the end position of the primary submovement and the target (i.e. error). The error in the young group was found to be significantly smaller than that in the middle-age and elderly groups, i.e., the error was larger for the higher age groups. These results suggest that young subjects have better control of preprogramed movement than middle-age or elderly subjects. Finally, we examined the temporal property of the primary submovement and its age-related changes. The duration of the primary submovement tended to be longer for the aged groups, although significance was reached only for the elderly group. In particular, the ratio of the duration of the primary submovement to total movement time tended to be lower for the aged groups, suggesting that the proportion of additional movements that are required to compensate for the incomplete control in the preprogramed movement, which are under feedback control, was higher for the aged groups. Consequently, our results indicate that the distance between the end point of the primary submovement and the target center (i.e. error) in the step-tracking movement is a useful parameter to evaluate the age-related changes in control of preprogramed movement.

Analysis for lateral deflection of railroad track under quasi-static loading

DOT National Transportation Integrated Search

2013-10-15

This paper describes analyses to examine the lateral : deflection of railroad track subjected to quasi-static loading. : Rails are assumed to behave as beams in bending. Movement : of the track in the lateral plane is constrained by idealized : resis...

Integrating Terrestrial Time-Lapse Photography with Laser Scanning to Distinguish the Drivers of Movement at Sólheimajökull, Iceland

NASA Astrophysics Data System (ADS)

How, P.; James, M. R.; Wynn, P.

2014-12-01

Glacier movement is attributed to a sensitive configuration of driving forces. Here, we present an approach designed to evaluate the drivers of movement at Sólheimajökull, an outlet glacier from the Myrdalsjökull ice cap, Iceland, through combining terrestrial time-lapse photography and laser scanning (TLS). A time-lapse camera (a dSLR with intervalometer and solar-recharged battery power supply) collected hourly data over the summer of 2013. The data are subject to all the difficulties that are usually present in long time-lapse sequences, such as highly variable illumination and visibility conditions, evolving surfaces, and camera instabilities. Feature-tracking software [1] was used to: 1) track regions of static topography (e.g. the skyline) from which camera alignment could be continuously updated throughout the sequence; and 2) track glacial surface features for velocity estimation. Absolute georeferencing of the image sequence was carried out by registering the camera to a TLS survey acquired at the beginning of the monitoring period. A second TLS survey (July 2013) provided an additional 3D surface. By assuming glacial features moved in approximately planimetrically straight lines between the two survey dates, combining the two TLS surfaces with the monoscopic feature tracking allows 3D feature tracks to be derived. Such tracks will enable contributions from different drivers (e.g. surface melting) to be extracted, even in imagery that is acquired not perpendicular to glacier motion. At Sólheimajökull, our aim is to elucidate any volcanic contribution to the observed movement.[1] http://www.lancaster.ac.uk/staff/jamesm/software/pointcatcher.htm

Ecological scale and seasonal heterogeneity in the spatial behaviors of giant pandas.

PubMed

Zhang, Zejun; Sheppard, James K; Swaisgood, Ronald R; Wang, Guan; Nie, Yonggang; Wei, Wei; Zhao, Naxun; Wei, Fuwen

2014-01-01

We report on the first study to track the spatial behaviors of wild giant pandas (Ailuropoda melanoleuca) using high-resolution global positioning system (GPS) telemetry. Between 2008 and 2009, 4 pandas (2 male and 2 female) were tracked in Foping Reserve, China for an average of 305 days (± 54.8 SE). Panda home ranges were larger than those of previous very high frequency tracking studies, with a bimodal distribution of space-use and distinct winter and summer centers of activity. Home range sizes were larger in winter than in summer, although there was considerable individual variability. All tracked pandas exhibited individualistic, unoriented and multiphasic movement paths, with a high level of tortuosity within seasonal core habitats and directed, linear, large-scale movements between habitats. Pandas moved from low elevation winter habitats to high elevation (>2000 m) summer habitats in May, when temperatures averaged 17.5 °C (± 0.3 SE), and these large-scale movements took <1 month to complete. The peak in panda mean elevation occurred in Jul, after which they began slow, large-scale movements back to winter habitats that were completed in Nov. An adult female panda made 2 longdistance movements during the mating season. Pandas remain close to rivers and streams during winter, possibly reflecting the elevated water requirements to digest their high-fiber food. Panda movement path tortuosity and first-passage-time as a function of spatial scale indicated a mean peak in habitat search effort and patch use of approximately 700 m. Despite a high degree of spatial overlap between panda home ranges, particularly in winter, we detected neither avoidance nor attraction behavior between conspecifics. © 2012 Wiley Publishing Asia Pty Ltd, ISZS and IOZ/CAS.

Can low-cost motion-tracking systems substitute a Polhemus system when researching social motor coordination in children?

PubMed

Romero, Veronica; Amaral, Joseph; Fitzpatrick, Paula; Schmidt, R C; Duncan, Amie W; Richardson, Michael J

2017-04-01

Functionally stable and robust interpersonal motor coordination has been found to play an integral role in the effectiveness of social interactions. However, the motion-tracking equipment required to record and objectively measure the dynamic limb and body movements during social interaction has been very costly, cumbersome, and impractical within a non-clinical or non-laboratory setting. Here we examined whether three low-cost motion-tracking options (Microsoft Kinect skeletal tracking of either one limb or whole body and a video-based pixel change method) can be employed to investigate social motor coordination. Of particular interest was the degree to which these low-cost methods of motion tracking could be used to capture and index the coordination dynamics that occurred between a child and an experimenter for three simple social motor coordination tasks in comparison to a more expensive, laboratory-grade motion-tracking system (i.e., a Polhemus Latus system). Overall, the results demonstrated that these low-cost systems cannot substitute the Polhemus system in some tasks. However, the lower-cost Microsoft Kinect skeletal tracking and video pixel change methods were successfully able to index differences in social motor coordination in tasks that involved larger-scale, naturalistic whole body movements, which can be cumbersome and expensive to record with a Polhemus. However, we found the Kinect to be particularly vulnerable to occlusion and the pixel change method to movements that cross the video frame midline. Therefore, particular care needs to be taken in choosing the motion-tracking system that is best suited for the particular research.

Automated regional analysis of B-mode ultrasound images of skeletal muscle movement

PubMed Central

Darby, John; Costen, Nicholas; Loram, Ian D.

2012-01-01

To understand the functional significance of skeletal muscle anatomy, a method of quantifying local shape changes in different tissue structures during dynamic tasks is required. Taking advantage of the good spatial and temporal resolution of B-mode ultrasound imaging, we describe a method of automatically segmenting images into fascicle and aponeurosis regions and tracking movement of features, independently, in localized portions of each tissue. Ultrasound images (25 Hz) of the medial gastrocnemius muscle were collected from eight participants during ankle joint rotation (2° and 20°), isometric contractions (1, 5, and 50 Nm), and deep knee bends. A Kanade-Lucas-Tomasi feature tracker was used to identify and track any distinctive and persistent features within the image sequences. A velocity field representation of local movement was then found and subdivided between fascicle and aponeurosis regions using segmentations from a multiresolution active shape model (ASM). Movement in each region was quantified by interpolating the effect of the fields on a set of probes. ASM segmentation results were compared with hand-labeled data, while aponeurosis and fascicle movement were compared with results from a previously documented cross-correlation approach. ASM provided good image segmentations (<1 mm average error), with fully automatic initialization possible in sequences from seven participants. Feature tracking provided similar length change results to the cross-correlation approach for small movements, while outperforming it in larger movements. The proposed method provides the potential to distinguish between active and passive changes in muscle shape and model strain distributions during different movements/conditions and quantify nonhomogeneous strain along aponeuroses. PMID:22033532

Implicit prosody mining based on the human eye image capture technology

NASA Astrophysics Data System (ADS)

Gao, Pei-pei; Liu, Feng

2013-08-01

The technology of eye tracker has become the main methods of analyzing the recognition issues in human-computer interaction. Human eye image capture is the key problem of the eye tracking. Based on further research, a new human-computer interaction method introduced to enrich the form of speech synthetic. We propose a method of Implicit Prosody mining based on the human eye image capture technology to extract the parameters from the image of human eyes when reading, control and drive prosody generation in speech synthesis, and establish prosodic model with high simulation accuracy. Duration model is key issues for prosody generation. For the duration model, this paper put forward a new idea for obtaining gaze duration of eyes when reading based on the eye image capture technology, and synchronous controlling this duration and pronunciation duration in speech synthesis. The movement of human eyes during reading is a comprehensive multi-factor interactive process, such as gaze, twitching and backsight. Therefore, how to extract the appropriate information from the image of human eyes need to be considered and the gaze regularity of eyes need to be obtained as references of modeling. Based on the analysis of current three kinds of eye movement control model and the characteristics of the Implicit Prosody reading, relative independence between speech processing system of text and eye movement control system was discussed. It was proved that under the same text familiarity condition, gaze duration of eyes when reading and internal voice pronunciation duration are synchronous. The eye gaze duration model based on the Chinese language level prosodic structure was presented to change previous methods of machine learning and probability forecasting, obtain readers' real internal reading rhythm and to synthesize voice with personalized rhythm. This research will enrich human-computer interactive form, and will be practical significance and application prospect in terms of disabled assisted speech interaction. Experiments show that Implicit Prosody mining based on the human eye image capture technology makes the synthesized speech has more flexible expressions.

Adaptive optics scanning laser ophthalmoscope using liquid crystal on silicon spatial light modulator: Performance study with involuntary eye movement

NASA Astrophysics Data System (ADS)

Huang, Hongxin; Toyoda, Haruyoshi; Inoue, Takashi

2017-09-01

The performance of an adaptive optics scanning laser ophthalmoscope (AO-SLO) using a liquid crystal on silicon spatial light modulator and Shack-Hartmann wavefront sensor was investigated. The system achieved high-resolution and high-contrast images of human retinas by dynamic compensation for the aberrations in the eyes. Retinal structures such as photoreceptor cells, blood vessels, and nerve fiber bundles, as well as blood flow, could be observed in vivo. We also investigated involuntary eye movements and ascertained microsaccades and drifts using both the retinal images and the aberrations recorded simultaneously. Furthermore, we measured the interframe displacement of retinal images and found that during eye drift, the displacement has a linear relationship with the residual low-order aberration. The estimated duration and cumulative displacement of the drift were within the ranges estimated by a video tracking technique. The AO-SLO would not only be used for the early detection of eye diseases, but would also offer a new approach for involuntary eye movement research.

Empirical Study on Designing of Gaze Tracking Camera Based on the Information of User's Head Movement.

PubMed

Pan, Weiyuan; Jung, Dongwook; Yoon, Hyo Sik; Lee, Dong Eun; Naqvi, Rizwan Ali; Lee, Kwan Woo; Park, Kang Ryoung

2016-08-31

Gaze tracking is the technology that identifies a region in space that a user is looking at. Most previous non-wearable gaze tracking systems use a near-infrared (NIR) light camera with an NIR illuminator. Based on the kind of camera lens used, the viewing angle and depth-of-field (DOF) of a gaze tracking camera can be different, which affects the performance of the gaze tracking system. Nevertheless, to our best knowledge, most previous researches implemented gaze tracking cameras without ground truth information for determining the optimal viewing angle and DOF of the camera lens. Eye-tracker manufacturers might also use ground truth information, but they do not provide this in public. Therefore, researchers and developers of gaze tracking systems cannot refer to such information for implementing gaze tracking system. We address this problem providing an empirical study in which we design an optimal gaze tracking camera based on experimental measurements of the amount and velocity of user's head movements. Based on our results and analyses, researchers and developers might be able to more easily implement an optimal gaze tracking system. Experimental results show that our gaze tracking system shows high performance in terms of accuracy, user convenience and interest.

Empirical Study on Designing of Gaze Tracking Camera Based on the Information of User’s Head Movement

PubMed Central

Pan, Weiyuan; Jung, Dongwook; Yoon, Hyo Sik; Lee, Dong Eun; Naqvi, Rizwan Ali; Lee, Kwan Woo; Park, Kang Ryoung

2016-01-01

Gaze tracking is the technology that identifies a region in space that a user is looking at. Most previous non-wearable gaze tracking systems use a near-infrared (NIR) light camera with an NIR illuminator. Based on the kind of camera lens used, the viewing angle and depth-of-field (DOF) of a gaze tracking camera can be different, which affects the performance of the gaze tracking system. Nevertheless, to our best knowledge, most previous researches implemented gaze tracking cameras without ground truth information for determining the optimal viewing angle and DOF of the camera lens. Eye-tracker manufacturers might also use ground truth information, but they do not provide this in public. Therefore, researchers and developers of gaze tracking systems cannot refer to such information for implementing gaze tracking system. We address this problem providing an empirical study in which we design an optimal gaze tracking camera based on experimental measurements of the amount and velocity of user’s head movements. Based on our results and analyses, researchers and developers might be able to more easily implement an optimal gaze tracking system. Experimental results show that our gaze tracking system shows high performance in terms of accuracy, user convenience and interest. PMID:27589768

Apparatus and method for tracking a molecule or particle in three dimensions

DOEpatents

Werner, James H [Los Alamos, NM; Goodwin, Peter M [Los Alamos, NM; Lessard, Guillaume [Santa Fe, NM

2009-03-03

An apparatus and method were used to track the movement of fluorescent particles in three dimensions. Control software was used with the apparatus to implement a tracking algorithm for tracking the motion of the individual particles in glycerol/water mixtures. Monte Carlo simulations suggest that the tracking algorithms in combination with the apparatus may be used for tracking the motion of single fluorescent or fluorescently labeled biomolecules in three dimensions.

Acoustic tracking of woodhead seabed drifters

NASA Technical Reports Server (NTRS)

Mayhue, R. J.; Lovelady, R. W.

1977-01-01

An investigation was conducted to determine the feasibility of tracking Woodhead seabed drifters that were instrumented with miniature acoustic transmitters having a range in water in excess of 1.0 n.mi. A trial cruise at the entrance of Delaware Bay, with the R.V. Annandale as the sonar-tracking vessel, verified acoustic communications and positioning of the bottom drifters. A demonstration cruise with the R.V. Annandale was also performed in the New York Bight to attempt to collect information on bottom water movement near the sewage-sluge dump site. Results from the tracking mission in the New York Bight suggested that bottom water currents were negligible near the dump site during the time interval from November 7-12, 1975, and that shipboard sonar tracking of acoustic Woodhead seabed drifters could provide useful Lagragian information on bottom water movement caused by tidal and other nonstorm effects.

Multiple particle tracking in 3-D+t microscopy: method and application to the tracking of endocytosed quantum dots.

PubMed

Genovesio, Auguste; Liedl, Tim; Emiliani, Valentina; Parak, Wolfgang J; Coppey-Moisan, Maité; Olivo-Marin, Jean-Christophe

2006-05-01

We propose a method to detect and track multiple moving biological spot-like particles showing different kinds of dynamics in image sequences acquired through multidimensional fluorescence microscopy. It enables the extraction and analysis of information such as number, position, speed, movement, and diffusion phases of, e.g., endosomal particles. The method consists of several stages. After a detection stage performed by a three-dimensional (3-D) undecimated wavelet transform, we compute, for each detected spot, several predictions of its future state in the next frame. This is accomplished thanks to an interacting multiple model (IMM) algorithm which includes several models corresponding to different biologically realistic movement types. Tracks are constructed, thereafter, by a data association algorithm based on the maximization of the likelihood of each IMM. The last stage consists of updating the IMM filters in order to compute final estimations for the present image and to improve predictions for the next image. The performances of the method are validated on synthetic image data and used to characterize the 3-D movement of endocytic vesicles containing quantum dots.

Interjoint coordination of the lower extremities in short-track speed skating.

PubMed

Khuyagbaatar, Batbayar; Purevsuren, Tserenchimed; Park, Won Man; Kim, Kyungsoo; Kim, Yoon Hyuk

2017-10-01

In short-track speed skating, the three-dimensional kinematics of the lower extremities during the whole skating cycle have not been studied. Kinematic parameters of the lower extremities during skating are presented as joint angles versus time. However, the angle-time presentation is not sufficient to describe the relationship between multi-joint movement patterns. Thus, angle-angle presentations were developed and used to describe interjoint coordination in sport activities. In this study, 15 professional male skaters' full body motion data were recorded using a wearable motion capture system during short-track speed skating. We investigated the three-dimensional kinematics of the lower extremities and then established the interjoint coordination between hip-knee and knee-ankle for both legs during the whole skating cycle. The results demonstrate the relationship between multi-joint movements during different phases of short-track speed skating. This study provides fundamentals of the movement mechanism of the lower extremities that can be integrated with physiotherapy to improve skating posture and prevent injuries from repetitive stress since physiological characteristics play an important role in skating performance.

Morphogenesis and three-dimensional movement of the stomach during the human embryonic period.

PubMed

Kaigai, N; Nako, A; Yamada, S; Uwabe, C; Kose, K; Takakuwa, T

2014-05-01

The stomach develops as the local widening of the foregut after Carnegie stage (CS) 13 that moves in a dramatic and dynamic manner during the embryonic period. Using the magnetic resonance images of 377 human embryos, we present the morphology, morphometry, and three-dimensional movement of the stomach during CS16 and CS23. The stomach morphology revealed stage-specific features. The angular incisura and the cardia were formed at CS18. The change in the angular incisura angle was approximately 90° during CS19 and CS20, and was <90° after CS 21. The prominent formations of the fundus and the pylorus differentiate at around CS20. Morphometry of the stomach revealed that the stomach gradually becomes "deflected" during development. The stomach may appear to move to the left laterally and caudally due to its deflection and differential growth. The track of the reference points in the stomach may reflect the visual three-dimensional movement. The movement of point M, representing the movement of the greater curvature, was different from that of points C (cardia) and P (pyloric antrum). The P and C were located just around the midsagittal plane in all the stages observed. Point M moved in the caudal-left lateral direction until CS22. Moreover, the vector CP does not rotate around the dorsoventral axis, as widely believed, but around the transverse axis. The plane CPM rotated mainly around the longitudinal axis. The data obtained will be useful for prenatal diagnosis in the near future. Copyright © 2013 Wiley Periodicals, Inc.

Satellite animal tracking feasibility studies

NASA Technical Reports Server (NTRS)

Buechner, H. K.

1975-01-01

A study was initiated in Tsavo National Park to determine movements and home ranges of individual elephants and their relations to overall distribution patterns and environmental factors such as rainfall. Methods used were radio tracking and observations of visually identifiable individuals. Aerial counts provided data on overall distribution. Two bulls and two cows were radio-tagged in Tsavo West and two bulls and four cows in Tsavo East, providing home range and movement data. The movements of individuals were useful in interpreting relatively major shifts in elephant distribution. Results point to the following preliminary conclusions: (1) elephants in the Tsavo area undertook long distance movements in fairly direct response to localized rainfall; (2) a subdivision of the overall population into locally distinct units may exist during the dry season but did not occur after significant rainfall; and (3) food appears to be the primary factor governing movements and distribution of elephants in the area.

Exploring patterns of movement suspension in pedestrian mobility.

PubMed

Orellana, Daniel; Wachowicz, Monica

2011-01-01

One of the main tasks in analyzing pedestrian movement is to detect places where pedestrians stop, as those places usually are associated with specific human activities, and they can allow us to understand pedestrian movement behavior. Very few approaches have been proposed to detect the locations of stops in positioning data sets, and they often are based on selecting the location of candidate stops as well as potential spatial and temporal thresholds according to different application requirements. However, these approaches are not suitable for analyzing the slow movement of pedestrians where the inaccuracy of a nondifferential global positioning system commonly used for movement tracking is so significant that it can hinder the selection of adequate thresholds. In this article, we propose an exploratory statistical approach to detect patterns of movement suspension using a local indicator of spatial association (LISA) in a vector space representation. Two different positioning data sets are used to evaluate our approach in terms of exploring movement suspension patterns that can be related to different landscapes: players of an urban outdoor mobile game and visitors of a natural park. The results of both experiments show that patterns of movement suspension were located at places such as checkpoints in the game and different attractions and facilities in the park. Based on these results, we conclude that using LISA is a reliable approach for exploring movement suspension patterns that represent the places where the movement of pedestrians is temporally suspended by physical restrictions (e.g., checkpoints of a mobile game and the route choosing points of a park).

Real-Time External Respiratory Motion Measuring Technique Using an RGB-D Camera and Principal Component Analysis †

PubMed Central

Wijenayake, Udaya; Park, Soon-Yong

2017-01-01

Accurate tracking and modeling of internal and external respiratory motion in the thoracic and abdominal regions of a human body is a highly discussed topic in external beam radiotherapy treatment. Errors in target/normal tissue delineation and dose calculation and the increment of the healthy tissues being exposed to high radiation doses are some of the unsolicited problems caused due to inaccurate tracking of the respiratory motion. Many related works have been introduced for respiratory motion modeling, but a majority of them highly depend on radiography/fluoroscopy imaging, wearable markers or surgical node implanting techniques. We, in this article, propose a new respiratory motion tracking approach by exploiting the advantages of an RGB-D camera. First, we create a patient-specific respiratory motion model using principal component analysis (PCA) removing the spatial and temporal noise of the input depth data. Then, this model is utilized for real-time external respiratory motion measurement with high accuracy. Additionally, we introduce a marker-based depth frame registration technique to limit the measuring area into an anatomically consistent region that helps to handle the patient movements during the treatment. We achieved a 0.97 correlation comparing to a spirometer and 0.53 mm average error considering a laser line scanning result as the ground truth. As future work, we will use this accurate measurement of external respiratory motion to generate a correlated motion model that describes the movements of internal tumors. PMID:28792468

Player Monitoring in Indoor Team Sports: Concurrent Validity of Inertial Measurement Units to Quantify Average and Peak Acceleration Values

PubMed Central

Roell, Mareike; Roecker, Kai; Gehring, Dominic; Mahler, Hubert; Gollhofer, Albert

2018-01-01

The increasing interest in assessing physical demands in team sports has led to the development of multiple sports related monitoring systems. Due to technical limitations, these systems primarily could be applied to outdoor sports, whereas an equivalent indoor locomotion analysis is not established yet. Technological development of inertial measurement units (IMU) broadens the possibilities for player monitoring and enables the quantification of locomotor movements in indoor environments. The aim of the current study was to validate an IMU measuring by determining average and peak human acceleration under indoor conditions in team sport specific movements. Data of a single wearable tracking device including an IMU (Optimeye S5, Catapult Sports, Melbourne, Australia) were compared to the results of a 3D motion analysis (MA) system (Vicon Motion Systems, Oxford, UK) during selected standardized movement simulations in an indoor laboratory (n = 56). A low-pass filtering method for gravity correction (LF) and two sensor fusion algorithms for orientation estimation [Complementary Filter (CF), Kalman-Filter (KF)] were implemented and compared with MA system data. Significant differences (p < 0.05) were found between LF and MA data but not between sensor fusion algorithms and MA. Higher precision and lower relative errors were found for CF (RMSE = 0.05; CV = 2.6%) and KF (RMSE = 0.15; CV = 3.8%) both compared to the LF method (RMSE = 1.14; CV = 47.6%) regarding the magnitude of the resulting vector and strongly emphasize the implementation of orientation estimation to accurately describe human acceleration. Comparing both sensor fusion algorithms, CF revealed slightly lower errors than KF and additionally provided valuable information about positive and negative acceleration values in all three movement planes with moderate to good validity (CV = 3.9 – 17.8%). Compared to x- and y-axis superior results were found for the z-axis. These findings demonstrate that IMU-based wearable tracking devices can successfully be applied for athlete monitoring in indoor team sports and provide potential to accurately quantify accelerations and decelerations in all three orthogonal axes with acceptable validity. An increase in accuracy taking magnetometers in account should be specifically pursued by future research. PMID:29535641

Finger tracking for hand-held device interface using profile-matching stereo vision

NASA Astrophysics Data System (ADS)

Chang, Yung-Ping; Lee, Dah-Jye; Moore, Jason; Desai, Alok; Tippetts, Beau

2013-01-01

Hundreds of millions of people use hand-held devices frequently and control them by touching the screen with their fingers. If this method of operation is being used by people who are driving, the probability of deaths and accidents occurring substantially increases. With a non-contact control interface, people do not need to touch the screen. As a result, people will not need to pay as much attention to their phones and thus drive more safely than they would otherwise. This interface can be achieved with real-time stereovision. A novel Intensity Profile Shape-Matching Algorithm is able to obtain 3-D information from a pair of stereo images in real time. While this algorithm does have a trade-off between accuracy and processing speed, the result of this algorithm proves the accuracy is sufficient for the practical use of recognizing human poses and finger movement tracking. By choosing an interval of disparity, an object at a certain distance range can be segmented. In other words, we detect the object by its distance to the cameras. The advantage of this profile shape-matching algorithm is that detection of correspondences relies on the shape of profile and not on intensity values, which are subjected to lighting variations. Based on the resulting 3-D information, the movement of fingers in space from a specific distance can be determined. Finger location and movement can then be analyzed for non-contact control of hand-held devices.

Arduino based radioactive tracking system

NASA Astrophysics Data System (ADS)

Rahman, Nur Aira Abd; Rashid, Mohd Fazlie Bin Abdul; Rahman, Anwar Bin Abdul; Ramlan, Atikah

2017-01-01

There is a clear need to strengthen security measures to prevent any malevolent use or accidental misuse of radioactive sources. Some of these radioactive sources are regularly transported outside of office or laboratory premises for work and consultation purposes. This paper present the initial development of radioactive source tracking system, which combined Arduino microcontroller, Global Positioning System (GPS) and Global System for Mobile communication (GSM) technologies. The tracking system will help the owner to monitor the movement of the radioactive sources. Currently, the system is capable of tracking the movement of radioactive source through the GPS satellite signals. The GPS co-ordinate could either be transmitted to headquarters at fixed interval via Short Messaging Service (SMS) to enable real time monitoring, or stored in a memory card for offline monitoring and data logging.

Transfer of Learning between Hemifields in Multiple Object Tracking: Memory Reduces Constraints of Attention

PubMed Central

Lapierre, Mark; Howe, Piers D. L.; Cropper, Simon J.

2013-01-01

Many tasks involve tracking multiple moving objects, or stimuli. Some require that individuals adapt to changing or unfamiliar conditions to be able to track well. This study explores processes involved in such adaptation through an investigation of the interaction of attention and memory during tracking. Previous research has shown that during tracking, attention operates independently to some degree in the left and right visual hemifields, due to putative anatomical constraints. It has been suggested that the degree of independence is related to the relative dominance of processes of attention versus processes of memory. Here we show that when individuals are trained to track a unique pattern of movement in one hemifield, that learning can be transferred to the opposite hemifield, without any evidence of hemifield independence. However, learning is not influenced by an explicit strategy of memorisation of brief periods of recognisable movement. The findings lend support to a role for implicit memory in overcoming putative anatomical constraints on the dynamic, distributed spatial allocation of attention involved in tracking multiple objects. PMID:24349555

Adaptive control based on an on-line parameter estimation of an upper limb exoskeleton.

PubMed

Riani, Akram; Madani, Tarek; Hadri, Abdelhafid El; Benallegue, Abdelaziz

2017-07-01

This paper presents an adaptive control strategy for an upper-limb exoskeleton based on an on-line dynamic parameter estimator. The objective is to improve the control performance of this system that plays a critical role in assisting patients for shoulder, elbow and wrist joint movements. In general, the dynamic parameters of the human limb are unknown and differ from a person to another, which degrade the performances of the exoskeleton-human control system. For this reason, the proposed control scheme contains a supplementary loop based on a new efficient on-line estimator of the dynamic parameters. Indeed, the latter is acting upon the parameter adaptation of the controller to ensure the performances of the system in the presence of parameter uncertainties and perturbations. The exoskeleton used in this work is presented and a physical model of the exoskeleton interacting with a 7 Degree of Freedom (DoF) upper limb model is generated using the SimMechanics library of MatLab/Simulink. To illustrate the effectiveness of the proposed approach, an example of passive rehabilitation movements is performed using multi-body dynamic simulation. The aims is to maneuver the exoskeleton that drive the upper limb to track desired trajectories in the case of the passive arm movements.

Multiple objects tracking in fluorescence microscopy.

PubMed

Kalaidzidis, Yannis

2009-01-01

Many processes in cell biology are connected to the movement of compact entities: intracellular vesicles and even single molecules. The tracking of individual objects is important for understanding cellular dynamics. Here we describe the tracking algorithms which have been developed in the non-biological fields and successfully applied to object detection and tracking in biological applications. The characteristics features of the different algorithms are compared.

Facial recognition in education system

NASA Astrophysics Data System (ADS)

Krithika, L. B.; Venkatesh, K.; Rathore, S.; Kumar, M. Harish

2017-11-01

Human beings exploit emotions comprehensively for conveying messages and their resolution. Emotion detection and face recognition can provide an interface between the individuals and technologies. The most successful applications of recognition analysis are recognition of faces. Many different techniques have been used to recognize the facial expressions and emotion detection handle varying poses. In this paper, we approach an efficient method to recognize the facial expressions to track face points and distances. This can automatically identify observer face movements and face expression in image. This can capture different aspects of emotion and facial expressions.

A path reconstruction method integrating dead-reckoning and position fixes applied to humpback whales.

PubMed

Wensveen, Paul J; Thomas, Len; Miller, Patrick J O

2015-01-01

Detailed information about animal location and movement is often crucial in studies of natural behaviour and how animals respond to anthropogenic activities. Dead-reckoning can be used to infer such detailed information, but without additional positional data this method results in uncertainty that grows with time. Combining dead-reckoning with new Fastloc-GPS technology should provide good opportunities for reconstructing georeferenced fine-scale tracks, and should be particularly useful for marine animals that spend most of their time under water. We developed a computationally efficient, Bayesian state-space modelling technique to estimate humpback whale locations through time, integrating dead-reckoning using on-animal sensors with measurements of whale locations using on-animal Fastloc-GPS and visual observations. Positional observation models were based upon error measurements made during calibrations. High-resolution 3-dimensional movement tracks were produced for 13 whales using a simple process model in which errors caused by water current movements, non-location sensor errors, and other dead-reckoning errors were accumulated into a combined error term. Positional uncertainty quantified by the track reconstruction model was much greater for tracks with visual positions and few or no GPS positions, indicating a strong benefit to using Fastloc-GPS for track reconstruction. Compared to tracks derived only from position fixes, the inclusion of dead-reckoning data greatly improved the level of detail in the reconstructed tracks of humpback whales. Using cross-validation, a clear improvement in the predictability of out-of-set Fastloc-GPS data was observed compared to more conventional track reconstruction methods. Fastloc-GPS observation errors during calibrations were found to vary by number of GPS satellites received and by orthogonal dimension analysed; visual observation errors varied most by distance to the whale. By systematically accounting for the observation errors in the position fixes, our model provides a quantitative estimate of location uncertainty that can be appropriately incorporated into analyses of animal movement. This generic method has potential application for a wide range of marine animal species and data recording systems.

The effect of image sharpness on quantitative eye movement data and on image quality evaluation while viewing natural images

NASA Astrophysics Data System (ADS)

Vuori, Tero; Olkkonen, Maria

2006-01-01

The aim of the study is to test both customer image quality rating (subjective image quality) and physical measurement of user behavior (eye movements tracking) to find customer satisfaction differences in imaging technologies. Methodological aim is to find out whether eye movements could be quantitatively used in image quality preference studies. In general, we want to map objective or physically measurable image quality to subjective evaluations and eye movement data. We conducted a series of image quality tests, in which the test subjects evaluated image quality while we recorded their eye movements. Results show that eye movement parameters consistently change according to the instructions given to the user, and according to physical image quality, e.g. saccade duration increased with increasing blur. Results indicate that eye movement tracking could be used to differentiate image quality evaluation strategies that the users have. Results also show that eye movements would help mapping between technological and subjective image quality. Furthermore, these results give some empirical emphasis to top-down perception processes in image quality perception and evaluation by showing differences between perceptual processes in situations when cognitive task varies.

Combining Recurrence Analysis and Automatic Movement Extraction from Video Recordings to Study Behavioral Coupling in Face-to-Face Parent-Child Interactions.

PubMed

López Pérez, David; Leonardi, Giuseppe; Niedźwiecka, Alicja; Radkowska, Alicja; Rączaszek-Leonardi, Joanna; Tomalski, Przemysław

2017-01-01

The analysis of parent-child interactions is crucial for the understanding of early human development. Manual coding of interactions is a time-consuming task, which is a limitation in many projects. This becomes especially demanding if a frame-by-frame categorization of movement needs to be achieved. To overcome this, we present a computational approach for studying movement coupling in natural settings, which is a combination of a state-of-the-art automatic tracker, Tracking-Learning-Detection (TLD), and nonlinear time-series analysis, Cross-Recurrence Quantification Analysis (CRQA). We investigated the use of TLD to extract and automatically classify movement of each partner from 21 video recordings of interactions, where 5.5-month-old infants and mothers engaged in free play in laboratory settings. As a proof of concept, we focused on those face-to-face episodes, where the mother animated an object in front of the infant, in order to measure the coordination between the infants' head movement and the mothers' hand movement. We also tested the feasibility of using such movement data to study behavioral coupling between partners with CRQA. We demonstrate that movement can be extracted automatically from standard definition video recordings and used in subsequent CRQA to quantify the coupling between movement of the parent and the infant. Finally, we assess the quality of this coupling using an extension of CRQA called anisotropic CRQA and show asymmetric dynamics between the movement of the parent and the infant. When combined these methods allow automatic coding and classification of behaviors, which results in a more efficient manner of analyzing movements than manual coding.

Combining Recurrence Analysis and Automatic Movement Extraction from Video Recordings to Study Behavioral Coupling in Face-to-Face Parent-Child Interactions

PubMed Central

López Pérez, David; Leonardi, Giuseppe; Niedźwiecka, Alicja; Radkowska, Alicja; Rączaszek-Leonardi, Joanna; Tomalski, Przemysław

2017-01-01

The analysis of parent-child interactions is crucial for the understanding of early human development. Manual coding of interactions is a time-consuming task, which is a limitation in many projects. This becomes especially demanding if a frame-by-frame categorization of movement needs to be achieved. To overcome this, we present a computational approach for studying movement coupling in natural settings, which is a combination of a state-of-the-art automatic tracker, Tracking-Learning-Detection (TLD), and nonlinear time-series analysis, Cross-Recurrence Quantification Analysis (CRQA). We investigated the use of TLD to extract and automatically classify movement of each partner from 21 video recordings of interactions, where 5.5-month-old infants and mothers engaged in free play in laboratory settings. As a proof of concept, we focused on those face-to-face episodes, where the mother animated an object in front of the infant, in order to measure the coordination between the infants' head movement and the mothers' hand movement. We also tested the feasibility of using such movement data to study behavioral coupling between partners with CRQA. We demonstrate that movement can be extracted automatically from standard definition video recordings and used in subsequent CRQA to quantify the coupling between movement of the parent and the infant. Finally, we assess the quality of this coupling using an extension of CRQA called anisotropic CRQA and show asymmetric dynamics between the movement of the parent and the infant. When combined these methods allow automatic coding and classification of behaviors, which results in a more efficient manner of analyzing movements than manual coding. PMID:29312075

CUE: counterfeit-resistant usable eye movement-based authentication via oculomotor plant characteristics and complex eye movement patterns

NASA Astrophysics Data System (ADS)

Komogortsev, Oleg V.; Karpov, Alexey; Holland, Corey D.

2012-06-01

The widespread use of computers throughout modern society introduces the necessity for usable and counterfeit-resistant authentication methods to ensure secure access to personal resources such as bank accounts, e-mail, and social media. Current authentication methods require tedious memorization of lengthy pass phrases, are often prone to shouldersurfing, and may be easily replicated (either by counterfeiting parts of the human body or by guessing an authentication token based on readily available information). This paper describes preliminary work toward a counterfeit-resistant usable eye movement-based (CUE) authentication method. CUE does not require any passwords (improving the memorability aspect of the authentication system), and aims to provide high resistance to spoofing and shoulder-surfing by employing the combined biometric capabilities of two behavioral biometric traits: 1) oculomotor plant characteristics (OPC) which represent the internal, non-visible, anatomical structure of the eye; 2) complex eye movement patterns (CEM) which represent the strategies employed by the brain to guide visual attention. Both OPC and CEM are extracted from the eye movement signal provided by an eye tracking system. Preliminary results indicate that the fusion of OPC and CEM traits is capable of providing a 30% reduction in authentication error when compared to the authentication accuracy of individual traits.

Sensor-based animal tracking

NASA Astrophysics Data System (ADS)

Hunter, Andrew

The advent of Global Positioning System (GPS) technologies has provided wildlife researchers with new insights into the movement and habitat utilization patterns of wildlife species by being able to provide vast quantities of detailed location data. However, current wildlife tracking techniques have numerous limitations, as GPS locations can be biased to an unknown extent because animals move through habitats that are often denied GPS signals. This can result in some habitat types being under sampled or not sampled at all. Additionally, researchers using GPS tracking systems cannot understand what behaviour an animal is exhibiting at each GPS position without either relying on extensive field data or statistical techniques that may infer behaviour. Overall these issues, and others, limit the knowledge that can be derived from the data currently being collected by GPS collars alone. To address these limitations, a dead reckoning solution (called the NavAid) has been developed to augment GPS tracking collars, which enables both the acquisition of continuous movement trajectories for animals under study, and the collection of digital images on a user-defined schedule along travel routes. Analysis of an animal's velocity allows one to identify different types of movement behaviours that can be associated with foraging, searching for food, and locomotion between patches. In addition, the ability to capture continuous paths allows researchers to identify habitat that is important to a species, and habitat that is not---something that is not possible when relying solely on GPS. This new system weighs approximately 220 g and can be deployed on most conventional collar systems for a wide range of species. This thesis presents the research and development of this new system over the past four years, along with preliminary findings from field work carried out on grizzly bears (Ursus arctos) in the foothills of the Canadian Rocky Mountains. Analysis of tracking data suggests that animals select different types of habitat for different purposes, that foraging occurs at movement rates of less than 52m/minute, searching for food between movement rates of 52 m/minute and 223 m/minute and locomotion, or active walking between foraging sites at movement rates greater than 223 m/minute.

Online Variational Bayesian Filtering-Based Mobile Target Tracking in Wireless Sensor Networks

PubMed Central

Zhou, Bingpeng; Chen, Qingchun; Li, Tiffany Jing; Xiao, Pei

2014-01-01

The received signal strength (RSS)-based online tracking for a mobile node in wireless sensor networks (WSNs) is investigated in this paper. Firstly, a multi-layer dynamic Bayesian network (MDBN) is introduced to characterize the target mobility with either directional or undirected movement. In particular, it is proposed to employ the Wishart distribution to approximate the time-varying RSS measurement precision's randomness due to the target movement. It is shown that the proposed MDBN offers a more general analysis model via incorporating the underlying statistical information of both the target movement and observations, which can be utilized to improve the online tracking capability by exploiting the Bayesian statistics. Secondly, based on the MDBN model, a mean-field variational Bayesian filtering (VBF) algorithm is developed to realize the online tracking of a mobile target in the presence of nonlinear observations and time-varying RSS precision, wherein the traditional Bayesian filtering scheme cannot be directly employed. Thirdly, a joint optimization between the real-time velocity and its prior expectation is proposed to enable online velocity tracking in the proposed online tacking scheme. Finally, the associated Bayesian Cramer–Rao Lower Bound (BCRLB) analysis and numerical simulations are conducted. Our analysis unveils that, by exploiting the potential state information via the general MDBN model, the proposed VBF algorithm provides a promising solution to the online tracking of a mobile node in WSNs. In addition, it is shown that the final tracking accuracy linearly scales with its expectation when the RSS measurement precision is time-varying. PMID:25393784

Memory Accumulation Mechanisms in Human Cortex Are Independent of Motor Intentions

PubMed Central

Tosoni, Annalisa; Mignogna, Valeria; McAvoy, Mark P.; Shulman, Gordon L.; Corbetta, Maurizio; Romani, Gian Luca

2014-01-01

Previous studies on perceptual decision-making have often emphasized a tight link between decisions and motor intentions. Human decisions, however, also depend on memories or experiences that are not closely tied to specific motor responses. Recent neuroimaging findings have suggested that, during episodic retrieval, parietal activity reflects the accumulation of evidence for memory decisions. It is currently unknown, however, whether these evidence accumulation signals are functionally linked to signals for motor intentions coded in frontoparietal regions and whether activity in the putative memory accumulator tracks the amount of evidence for only previous experience, as reflected in “old” reports, or for both old and new decisions, as reflected in the accuracy of memory judgments. Here, human participants used saccadic-eye and hand-pointing movements to report recognition judgments on pictures defined by different degrees of evidence for old or new decisions. A set of cortical regions, including the middle intraparietal sulcus, showed a monotonic variation of the fMRI BOLD signal that scaled with perceived memory strength (older > newer), compatible with an asymmetrical memory accumulator. Another set, including the hippocampus and the angular gyrus, showed a nonmonotonic response profile tracking memory accuracy (higher > lower evidence), compatible with a symmetrical accumulator. In contrast, eye and hand effector-specific regions in frontoparietal cortex tracked motor intentions but were not modulated by the amount of evidence for the effector outcome. We conclude that item recognition decisions are supported by a combination of symmetrical and asymmetrical accumulation signals largely segregated from motor intentions. PMID:24828652

Recognizing Induced Emotions of Happiness and Sadness from Dance Movement

PubMed Central

Van Dyck, Edith; Vansteenkiste, Pieter; Lenoir, Matthieu; Lesaffre, Micheline; Leman, Marc

2014-01-01

Recent research revealed that emotional content can be successfully decoded from human dance movement. Most previous studies made use of videos of actors or dancers portraying emotions through choreography. The current study applies emotion induction techniques and free movement in order to examine the recognition of emotional content from dance. Observers (N = 30) watched a set of silent videos showing depersonalized avatars of dancers moving to an emotionally neutral musical stimulus after emotions of either sadness or happiness had been induced. Each of the video clips consisted of two dance performances which were presented side-by-side and were played simultaneously; one of a dancer in the happy condition and one of the same individual in the sad condition. After every film clip, the observers were asked to make forced-choices concerning the emotional state of the dancer. Results revealed that observers were able to identify the emotional state of the dancers with a high degree of accuracy. Moreover, emotions were more often recognized for female dancers than for their male counterparts. In addition, the results of eye tracking measurements unveiled that observers primarily focus on movements of the chest when decoding emotional information from dance movement. The findings of our study show that not merely portrayed emotions, but also induced emotions can be successfully recognized from free dance movement. PMID:24587026

Linear array of photodiodes to track a human speaker for video recording

NASA Astrophysics Data System (ADS)

DeTone, D.; Neal, H.; Lougheed, R.

2012-12-01

Communication and collaboration using stored digital media has garnered more interest by many areas of business, government and education in recent years. This is due primarily to improvements in the quality of cameras and speed of computers. An advantage of digital media is that it can serve as an effective alternative when physical interaction is not possible. Video recordings that allow for viewers to discern a presenter's facial features, lips and hand motions are more effective than videos that do not. To attain this, one must maintain a video capture in which the speaker occupies a significant portion of the captured pixels. However, camera operators are costly, and often do an imperfect job of tracking presenters in unrehearsed situations. This creates motivation for a robust, automated system that directs a video camera to follow a presenter as he or she walks anywhere in the front of a lecture hall or large conference room. Such a system is presented. The system consists of a commercial, off-the-shelf pan/tilt/zoom (PTZ) color video camera, a necklace of infrared LEDs and a linear photodiode array detector. Electronic output from the photodiode array is processed to generate the location of the LED necklace, which is worn by a human speaker. The computer controls the video camera movements to record video of the speaker. The speaker's vertical position and depth are assumed to remain relatively constant- the video camera is sent only panning (horizontal) movement commands. The LED necklace is flashed at 70Hz at a 50% duty cycle to provide noise-filtering capability. The benefit to using a photodiode array versus a standard video camera is its higher frame rate (4kHz vs. 60Hz). The higher frame rate allows for the filtering of infrared noise such as sunlight and indoor lighting-a capability absent from other tracking technologies. The system has been tested in a large lecture hall and is shown to be effective.

The perception of heading during eye movements

NASA Technical Reports Server (NTRS)

Royden, Constance S.; Banks, Martin S.; Crowell, James A.

1992-01-01

Warren and Hannon (1988, 1990), while studying the perception of heading during eye movements, concluded that people do not require extraretinal information to judge heading with eye/head movements present. Here, heading judgments are examined at higher, more typical eye movement velocities than the extremely slow tracking eye movements used by Warren and Hannon. It is found that people require extraretinal information about eye position to perceive heading accurately under many viewing conditions.

Soft Smart Garments for Lower Limb Joint Position Analysis.

PubMed

Totaro, Massimo; Poliero, Tommaso; Mondini, Alessio; Lucarotti, Chiara; Cairoli, Giovanni; Ortiz, Jesùs; Beccai, Lucia

2017-10-12

Revealing human movement requires lightweight, flexible systems capable of detecting mechanical parameters (like strain and pressure) while being worn comfortably by the user, and not interfering with his/her activity. In this work we address such multifaceted challenge with the development of smart garments for lower limb motion detection, like a textile kneepad and anklet in which soft sensors and readout electronics are embedded for retrieving movement of the specific joint. Stretchable capacitive sensors with a three-electrode configuration are built combining conductive textiles and elastomeric layers, and distributed around knee and ankle. Results show an excellent behavior in the ~30% strain range, hence the correlation between sensors' responses and the optically tracked Euler angles is allowed for basic lower limb movements. Bending during knee flexion/extension is detected, and it is discriminated from any external contact by implementing in real time a low computational algorithm. The smart anklet is designed to address joint motion detection in and off the sagittal plane. Ankle dorsi/plantar flexion, adduction/abduction, and rotation are retrieved. Both knee and ankle smart garments show a high accuracy in movement detection, with a RMSE less than 4° in the worst case.

Soft Smart Garments for Lower Limb Joint Position Analysis

PubMed Central

Totaro, Massimo; Poliero, Tommaso; Mondini, Alessio; Lucarotti, Chiara; Cairoli, Giovanni; Ortiz, Jesùs; Beccai, Lucia

2017-01-01

Revealing human movement requires lightweight, flexible systems capable of detecting mechanical parameters (like strain and pressure) while being worn comfortably by the user, and not interfering with his/her activity. In this work we address such multifaceted challenge with the development of smart garments for lower limb motion detection, like a textile kneepad and anklet in which soft sensors and readout electronics are embedded for retrieving movement of the specific joint. Stretchable capacitive sensors with a three-electrode configuration are built combining conductive textiles and elastomeric layers, and distributed around knee and ankle. Results show an excellent behavior in the ~30% strain range, hence the correlation between sensors’ responses and the optically tracked Euler angles is allowed for basic lower limb movements. Bending during knee flexion/extension is detected, and it is discriminated from any external contact by implementing in real time a low computational algorithm. The smart anklet is designed to address joint motion detection in and off the sagittal plane. Ankle dorsi/plantar flexion, adduction/abduction, and rotation are retrieved. Both knee and ankle smart garments show a high accuracy in movement detection, with a RMSE less than 4° in the worst case. PMID:29023365

Tracking without perceiving: a dissociation between eye movements and motion perception.

PubMed

Spering, Miriam; Pomplun, Marc; Carrasco, Marisa

2011-02-01

Can people react to objects in their visual field that they do not consciously perceive? We investigated how visual perception and motor action respond to moving objects whose visibility is reduced, and we found a dissociation between motion processing for perception and for action. We compared motion perception and eye movements evoked by two orthogonally drifting gratings, each presented separately to a different eye. The strength of each monocular grating was manipulated by inducing adaptation to one grating prior to the presentation of both gratings. Reflexive eye movements tracked the vector average of both gratings (pattern motion) even though perceptual responses followed one motion direction exclusively (component motion). Observers almost never perceived pattern motion. This dissociation implies the existence of visual-motion signals that guide eye movements in the absence of a corresponding conscious percept.

Tracking Without Perceiving: A Dissociation Between Eye Movements and Motion Perception

PubMed Central

Spering, Miriam; Pomplun, Marc; Carrasco, Marisa

2011-01-01

Can people react to objects in their visual field that they do not consciously perceive? We investigated how visual perception and motor action respond to moving objects whose visibility is reduced, and we found a dissociation between motion processing for perception and for action. We compared motion perception and eye movements evoked by two orthogonally drifting gratings, each presented separately to a different eye. The strength of each monocular grating was manipulated by inducing adaptation to one grating prior to the presentation of both gratings. Reflexive eye movements tracked the vector average of both gratings (pattern motion) even though perceptual responses followed one motion direction exclusively (component motion). Observers almost never perceived pattern motion. This dissociation implies the existence of visual-motion signals that guide eye movements in the absence of a corresponding conscious percept. PMID:21189353

Seasonal movements and environmental triggers to fall migration of Sage Sparrows

USGS Publications Warehouse

Fesenmyer, K.A.; Knick, S.T.

2011-01-01

Post-breeding ecology of shrubland passerines prior to onset of migration is unknown relative to dynamics of breeding areas. We radiomarked and monitored 38 Sage Sparrows (Amphispiza belli ssp. nevadensis) at one site in Oregon and two in Nevada from September to mid-November 2007 to track local movements, estimate seasonal range sizes, and characterize weather patterns triggering onset of migration. Median area used by Sage Sparrows monitored between 3 and 18 days during or prior to migration was 14 ha; maximum daily movement was 15 km. Radio-marked Sage Sparrows at each location departed individually, rather than en masse, corresponding with passage of cold front weather systems. Conventional telemetry techniques limited our ability to monitor Sage Sparrows beyond pre-migratory periods and precluded detecting and tracking actual movements during migration. ?? 2011 by the Wilson Ornithological Society.

Geometry and Gesture-Based Features from Saccadic Eye-Movement as a Biometric in Radiology

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

Hammond, Tracy; Tourassi, Georgia; Yoon, Hong-Jun

In this study, we present a novel application of sketch gesture recognition on eye-movement for biometric identification and estimating task expertise. The study was performed for the task of mammographic screening with simultaneous viewing of four coordinated breast views as typically done in clinical practice. Eye-tracking data and diagnostic decisions collected for 100 mammographic cases (25 normal, 25 benign, 50 malignant) and 10 readers (three board certified radiologists and seven radiology residents), formed the corpus for this study. Sketch gesture recognition techniques were employed to extract geometric and gesture-based features from saccadic eye-movements. Our results show that saccadic eye-movement, characterizedmore » using sketch-based features, result in more accurate models for predicting individual identity and level of expertise than more traditional eye-tracking features.« less

Simultaneous nano-tracking of multiple motor proteins via spectral discrimination of quantum dots.

PubMed

Kakizuka, Taishi; Ikezaki, Keigo; Kaneshiro, Junichi; Fujita, Hideaki; Watanabe, Tomonobu M; Ichimura, Taro

2016-07-01

Simultaneous nanometric tracking of multiple motor proteins was achieved by combining multicolor fluorescent labeling of target proteins and imaging spectroscopy, revealing dynamic behaviors of multiple motor proteins at the sub-diffraction-limit scale. Using quantum dot probes of distinct colors, we experimentally verified the localization precision to be a few nanometers at temporal resolution of 30 ms or faster. One-dimensional processive movement of two heads of a single myosin molecule and multiple myosin molecules was successfully traced. Furthermore, the system was modified for two-dimensional measurement and applied to tracking of multiple myosin molecules. Our approach is useful for investigating cooperative movement of proteins in supramolecular nanomachinery.

Simultaneous nano-tracking of multiple motor proteins via spectral discrimination of quantum dots

PubMed Central

Kakizuka, Taishi; Ikezaki, Keigo; Kaneshiro, Junichi; Fujita, Hideaki; Watanabe, Tomonobu M.; Ichimura, Taro

2016-01-01

Simultaneous nanometric tracking of multiple motor proteins was achieved by combining multicolor fluorescent labeling of target proteins and imaging spectroscopy, revealing dynamic behaviors of multiple motor proteins at the sub-diffraction-limit scale. Using quantum dot probes of distinct colors, we experimentally verified the localization precision to be a few nanometers at temporal resolution of 30 ms or faster. One-dimensional processive movement of two heads of a single myosin molecule and multiple myosin molecules was successfully traced. Furthermore, the system was modified for two-dimensional measurement and applied to tracking of multiple myosin molecules. Our approach is useful for investigating cooperative movement of proteins in supramolecular nanomachinery. PMID:27446684

Gaze Estimation Method Using Analysis of Electrooculogram Signals and Kinect Sensor

PubMed Central

Tanno, Koichi

2017-01-01

A gaze estimation system is one of the communication methods for severely disabled people who cannot perform gestures and speech. We previously developed an eye tracking method using a compact and light electrooculogram (EOG) signal, but its accuracy is not very high. In the present study, we conducted experiments to investigate the EOG component strongly correlated with the change of eye movements. The experiments in this study are of two types: experiments to see objects only by eye movements and experiments to see objects by face and eye movements. The experimental results show the possibility of an eye tracking method using EOG signals and a Kinect sensor. PMID:28912800

Migrations of California gray whales tracked by oxygen-18 variations in their epizoic barnacles

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

Killingley, J.S.

1980-02-15

Barnacles attached to the California gray whale have oxygen isotope compositions that serve as a record of changing ocean temperatures as the whale migrates between arctic and subtropical waters. The isotopic values for the barnacles can be used to track whale migrations and to reconstruct the recent movements of beached whales. The method may be useful for tracing the movements of other animals, living or fossil, and for reconstructing the voyages of ancient ships.

Assessing senescence in Drosophila using video tracking.

PubMed

Ardekani, Reza; Tavaré, Simon; Tower, John

2013-01-01

Senescence is associated with changes in gene expression, including the upregulation of stress response- and innate immune response-related genes. In addition, aging animals exhibit characteristic changes in movement behaviors including decreased gait speed and a deterioration in sleep/wake rhythms. Here, we describe methods for tracking Drosophila melanogaster movements in 3D with simultaneous quantification of fluorescent transgenic reporters. This approach allows for the assessment of correlations between behavior, aging, and gene expression as well as for the quantification of biomarkers of aging.

Spring hunting changes the regional movements of migrating greater snow geese

USGS Publications Warehouse

Bechet, A.; Giroux, J.-F.; Gauthier, G.; Nichols, J.D.; Hines, J.E.

2003-01-01

1. Human-induced disturbance such as hunting may influence the migratory behaviour of long-distance migrants. In 1999 and 2000 a spring hunt of greater snow geese Anser caerulescens atlanticus occurred for the first time in North America since 1916, aimed at stopping population growth to protect natural habitats. 2. We evaluated the impact of this hunt on the staging movements of geese along a 600-km stretch of the St. Lawrence River in southern Quebec, Canada. 3. We tracked radio-tagged female geese in three contiguous regions of the staging area from the south-west to the north-east: Lake St Pierre, Upper Estuary and Lower Estuary, in spring 1997 (n = 37) and 1998 (n = 70) before the establishment of hunting, and in 1999 (n = 60) and 2000 (n = 59) during hunting. 4. We used multi-state capture-recapture models to estimate the movement probabilities of radio-tagged females among these regions. To assess disturbance level, we tracked geese during their feeding trips and estimated the probability of completing a foraging bout without being disturbed. 5. In the 2 years without hunting, migration was strongly unidirectional from the south-west to the north-east, with very low westward movement probabilities. Geese gradually moved from Lake St Pierre to Upper Estuary and then from Upper Estuary to Lower Estuary. 6. In contrast, during the 2 years with hunting westward movement was more than four times more likely than in preceding years. Most of these backward movements occurred shortly after the beginning of the hunt, indicating that geese moved back to regions where they had not previously experienced hunting. 7. Overall disturbance level increased in all regions in years with hunting relative to years without hunting. 8. Synthesis and applications. We conclude that spring hunting changed the stopover scheduling of this long-distance migrant and might further impact population dynamics by reducing prenuptial fattening. The spring hunt may also have increased crop damage. We propose that staggered hunt opening dates could attenuate secondary effects of such management actions.

Lissencephaly-1 is a context-dependent regulator of the human dynein complex

PubMed Central

Baumbach, Janina; Murthy, Andal; McClintock, Mark A; Dix, Carly I; Zalyte, Ruta; Hoang, Ha Thi; Bullock, Simon L

2017-01-01

The cytoplasmic dynein-1 (dynein) motor plays a central role in microtubule organisation and cargo transport. These functions are spatially regulated by association of dynein and its accessory complex dynactin with dynamic microtubule plus ends. Here, we elucidate in vitro the roles of dynactin, end-binding protein-1 (EB1) and Lissencephaly-1 (LIS1) in the interaction of end tracking and minus end-directed human dynein complexes with these sites. LIS1 promotes dynactin-dependent tracking of dynein on both growing and shrinking plus ends. LIS1 also increases the frequency and velocity of processive dynein movements that are activated by complex formation with dynactin and a cargo adaptor. This stimulatory effect of LIS1 contrasts sharply with its documented ability to inhibit the activity of isolated dyneins. Collectively, our findings shed light on how mammalian dynein complexes associate with dynamic microtubules and help clarify how LIS1 promotes the plus-end localisation and cargo transport functions of dynein in vivo. DOI: http://dx.doi.org/10.7554/eLife.21768.001 PMID:28406398

The IBM HeadTracking Pointer: improvements in vision-based pointer control.

PubMed

Kjeldsen, Rick

2008-07-01

Vision-based head trackers have been around for some years and are even beginning to be commercialized, but problems remain with respect to usability. Users without the ability to use traditional pointing devices--the intended audience of such systems--have no alternative if the automatic bootstrapping process fails. There is room for improvement in face tracking, and the pointer movement dynamics do not support accurate and efficient pointing. This paper describes the IBM HeadTracking Pointer, a system which attempts to directly address some of these issues. Head gestures are used to provide the end user a greater level of autonomous control over the system. A novel face-tracking algorithm reduces drift under variable lighting conditions, allowing the use of absolute, rather than relative, pointer positioning. Most importantly, the pointer dynamics have been designed to take into account the constraints of head-based pointing, with a non-linear gain which allows stability in fine pointer movement, high speed on long transitions and adjustability to support users with different movement dynamics. User studies have identified some difficulties with training the system and some characteristics of the pointer motion that take time to get used to, but also good user feedback and very promising performance results.

What do eye movements tell us about patients with neurological disorders? — An introduction to saccade recording in the clinical setting —

PubMed Central

TERAO, Yasuo; FUKUDA, Hideki; HIKOSAKA, Okihide

2017-01-01

Non-invasive and readily implemented in the clinical setting, eye movement studies have been conducted extensively not only in healthy human subjects but also in patients with neurological disorders. The purpose of saccade studies is to “read out” the pathophysiology underlying neurological disorders from the saccade records, referring to known primate physiology. In the current review, we provide an overview of studies in which we attempted to elucidate the patterns of saccade abnormalities in over 250 patients with neurological disorders, including cerebellar ataxia and brainstem pathology due to neurodegenerative disorders, and what they tell about the pathophysiology of patients with neurological disorders. We also discuss how interventions, such as deep brain stimulation, affect saccade performance and provide further insights into the workings of the oculomotor system in humans. Finally, we argue that it is important to understand the functional significance and behavioral correlate of saccade abnormalities in daily life, which could require eye tracking methodologies to be performed in settings similar to daily life. PMID:29225306

Enabling Disabled Persons to Gain Access to Digital Media

NASA Technical Reports Server (NTRS)

Beach, Glenn; OGrady, Ryan

2011-01-01

A report describes the first phase in an effort to enhance the NaviGaze software to enable profoundly disabled persons to operate computers. (Running on a Windows-based computer equipped with a video camera aimed at the user s head, the original NaviGaze software processes the user's head movements and eye blinks into cursor movements and mouse clicks to enable hands-free control of the computer.) To accommodate large variations in movement capabilities among disabled individuals, one of the enhancements was the addition of a graphical user interface for selection of parameters that affect the way the software interacts with the computer and tracks the user s movements. Tracking algorithms were improved to reduce sensitivity to rotations and reduce the likelihood of tracking the wrong features. Visual feedback to the user was improved to provide an indication of the state of the computer system. It was found that users can quickly learn to use the enhanced software, performing single clicks, double clicks, and drags within minutes of first use. Available programs that could increase the usability of NaviGaze were identified. One of these enables entry of text by using NaviGaze as a mouse to select keys on a virtual keyboard.

A software-based tool for video motion tracking in the surgical skills assessment landscape.

PubMed

Ganni, Sandeep; Botden, Sanne M B I; Chmarra, Magdalena; Goossens, Richard H M; Jakimowicz, Jack J

2018-01-16

The use of motion tracking has been proved to provide an objective assessment in surgical skills training. Current systems, however, require the use of additional equipment or specialised laparoscopic instruments and cameras to extract the data. The aim of this study was to determine the possibility of using a software-based solution to extract the data. 6 expert and 23 novice participants performed a basic laparoscopic cholecystectomy procedure in the operating room. The recorded videos were analysed using Kinovea 0.8.15 and the following parameters calculated the path length, average instrument movement and number of sudden or extreme movements. The analysed data showed that experts had significantly shorter path length (median 127 cm vs. 187 cm, p = 0.01), smaller average movements (median 0.40 cm vs. 0.32 cm, p = 0.002) and fewer sudden movements (median 14.00 vs. 21.61, p = 0.001) than their novice counterparts. The use of software-based video motion tracking of laparoscopic cholecystectomy is a simple and viable method enabling objective assessment of surgical performance. It provides clear discrimination between expert and novice performance.

Tracking butterfly movements with harmonic radar reveals an effect of population age on movement distance

PubMed Central

Ovaskainen, Otso; Smith, Alan D.; Osborne, Juliet L.; Reynolds, Don R.; Carreck, Norman L.; Martin, Andrew P.; Niitepõld, Kristjan; Hanski, Ilkka

2008-01-01

We used harmonic radar to track freely flying Glanville fritillary butterfly (Melitaea cinxia) females within an area of 30 ha. Butterflies originated from large and continuous populations in China and Estonia, and from newly established or old (> 5 years) small local populations in a highly fragmented landscape in Finland. Caterpillars were raised under common garden conditions and unmated females were tested soon after eclosion. The reconstructed flight paths for 66 individuals comprised a total distance of 51 km with high spatial resolution. Butterflies originating from large continuous populations and from old local populations in Finland exhibited similar movement behaviors, whereas butterflies originating from newly established local populations in the fragmented landscape in Finland moved significantly more than the others. There was no difference in the lengths of individual flight bouts, but the new-population females flew more frequently, resulting in longer daily movement tracks. The flight activity of all individuals was affected by environmental conditions, peaking at 19–23°C (depending on population type), in the early afternoon, and during calm weather. Butterflies from all population types showed a strong tendency to follow habitat edges between the open study area and the neighboring woodlands. PMID:19060191

Collective movement in ecology: from emerging technologies to conservation and management.

PubMed

Westley, Peter A H; Berdahl, Andrew M; Torney, Colin J; Biro, Dora

2018-05-19

Recent advances in technology and quantitative methods have led to the emergence of a new field of study that stands to link insights of researchers from two closely related, but often disconnected disciplines: movement ecology and collective animal behaviour. To date, the field of movement ecology has focused on elucidating the internal and external drivers of animal movement and the influence of movement on broader ecological processes. Typically, tracking and/or remote sensing technology is employed to study individual animals in natural conditions. By contrast, the field of collective behaviour has quantified the significant role social interactions play in the decision-making of animals within groups and, to date, has predominantly relied on controlled laboratory-based studies and theoretical models owing to the constraints of studying interacting animals in the field. This themed issue is intended to formalize the burgeoning field of collective movement ecology which integrates research from both movement ecology and collective behaviour. In this introductory paper, we set the stage for the issue by briefly examining the approaches and current status of research in these areas. Next, we outline the structure of the theme issue and describe the obstacles collective movement researchers face, from data acquisition in the field to analysis and problems of scale, and highlight the key contributions of the assembled papers. We finish by presenting research that links individual and broad-scale ecological and evolutionary processes to collective movement, and finally relate these concepts to emerging challenges for the management and conservation of animals on the move in a world that is increasingly impacted by human activity.This article is part of the theme issue 'Collective movement ecology'. © 2018 The Author(s).

Eye Tracking: A Brief Guide for Developmental Researchers

ERIC Educational Resources Information Center

Feng, Gary

2011-01-01

Eye tracking offers a powerful research tool for developmental scientists. In this brief article, the author introduces the methodology and issues associated with its applications in developmental research, beginning with an overview of eye movements and eye-tracking technologies, followed by examples of how it is used to study the developing mind…

Eye-Tracking Study of Complexity in Gas Law Problems

ERIC Educational Resources Information Center

Tang, Hui; Pienta, Norbert

2012-01-01

This study, part of a series investigating students' use of online tools to assess problem solving, uses eye-tracking hardware and software to explore the effect of problem difficulty and cognitive processes when students solve gas law word problems. Eye movements are indices of cognition; eye-tracking data typically include the location,…

Use of Cognitive and Metacognitive Strategies in Online Search: An Eye-Tracking Study

ERIC Educational Resources Information Center

Zhou, Mingming; Ren, Jing

2016-01-01

This study used eye-tracking technology to track students' eye movements while searching information on the web. The research question guiding this study was "Do students with different search performance levels have different visual attention distributions while searching information online? If yes, what are the patterns for high and low…

A marker-free system for the analysis of movement disabilities.

PubMed

Legrand, L; Marzani, F; Dusserre, L

1998-01-01

A major step toward improving the treatments of disabled persons may be achieved by using motion analysis equipment. We are developing such a system. It allows the analysis of plane human motion (e.g. gait) without using the tracking of markers. The system is composed of one fixed camera which acquires an image sequence of a human in motion. Then the treatment is divided into two steps: first, a large number of pixels belonging to the boundaries of the human body are extracted at each acquisition time. Secondly, a two-dimensional model of the human body, based on tapered superquadrics, is successively matched with the sets of pixels previously extracted; a specific fuzzy clustering process is used for this purpose. Moreover, an optical flow procedure gives a prediction of the model location at each acquisition time from its location at the previous time. Finally we present some results of this process applied to a leg in motion.

Do Curved Reaching Movements Emerge from Competing Perceptions? A Reply to van der Wel et al. (2009)

ERIC Educational Resources Information Center

Spivey, Michael J.; Dale, Rick; Knoblich, Guenther; Grosjean, Marc

2010-01-01

Spivey, Grosjean, and Knoblich (2005) reported smoothly curved reaching movements, via computer-mouse tracking, which suggested a continuously evolving flow of distributed lexical activation patterns into motor movement during a phonological competitor task. For example, when instructed to click the "candy," participants' mouse-cursor trajectories…

Low-cost solar tracking system

NASA Technical Reports Server (NTRS)

Miller, C. G.; Stephens, J. B.

1975-01-01

Smaller heat-collector is moved to stay in focus with the sun, instead of moving reflector. Tracking can be controlled by storing data of predicted solar positions or by applying conventional sun-sensing devices to follow solar movement.

Video-based eye tracking for neuropsychiatric assessment.

PubMed

Adhikari, Sam; Stark, David E

2017-01-01

This paper presents a video-based eye-tracking method, ideally deployed via a mobile device or laptop-based webcam, as a tool for measuring brain function. Eye movements and pupillary motility are tightly regulated by brain circuits, are subtly perturbed by many disease states, and are measurable using video-based methods. Quantitative measurement of eye movement by readily available webcams may enable early detection and diagnosis, as well as remote/serial monitoring, of neurological and neuropsychiatric disorders. We successfully extracted computational and semantic features for 14 testing sessions, comprising 42 individual video blocks and approximately 17,000 image frames generated across several days of testing. Here, we demonstrate the feasibility of collecting video-based eye-tracking data from a standard webcam in order to assess psychomotor function. Furthermore, we were able to demonstrate through systematic analysis of this data set that eye-tracking features (in particular, radial and tangential variance on a circular visual-tracking paradigm) predict performance on well-validated psychomotor tests. © 2017 New York Academy of Sciences.

A hidden Markov model for reconstructing animal paths from solar geolocation loggers using templates for light intensity.

PubMed

Rakhimberdiev, Eldar; Winkler, David W; Bridge, Eli; Seavy, Nathaniel E; Sheldon, Daniel; Piersma, Theunis; Saveliev, Anatoly

2015-01-01

Solar archival tags (henceforth called geolocators) are tracking devices deployed on animals to reconstruct their long-distance movements on the basis of locations inferred post hoc with reference to the geographical and seasonal variations in the timing and speeds of sunrise and sunset. The increased use of geolocators has created a need for analytical tools to produce accurate and objective estimates of migration routes that are explicit in their uncertainty about the position estimates. We developed a hidden Markov chain model for the analysis of geolocator data. This model estimates tracks for animals with complex migratory behaviour by combining: (1) a shading-insensitive, template-fit physical model, (2) an uncorrelated random walk movement model that includes migratory and sedentary behavioural states, and (3) spatially explicit behavioural masks. The model is implemented in a specially developed open source R package FLightR. We used the particle filter (PF) algorithm to provide relatively fast model posterior computation. We illustrate our modelling approach with analysis of simulated data for stationary tags and of real tracks of both a tree swallow Tachycineta bicolor migrating along the east and a golden-crowned sparrow Zonotrichia atricapilla migrating along the west coast of North America. We provide a model that increases accuracy in analyses of noisy data and movements of animals with complicated migration behaviour. It provides posterior distributions for the positions of animals, their behavioural states (e.g., migrating or sedentary), and distance and direction of movement. Our approach allows biologists to estimate locations of animals with complex migratory behaviour based on raw light data. This model advances the current methods for estimating migration tracks from solar geolocation, and will benefit a fast-growing number of tracking studies with this technology.

Three-dimensional displacements of a large volcano flank movement during the May 2010 eruptions at Pacaya Volcano, Guatemala

NASA Astrophysics Data System (ADS)

Schaefer, L. N.; Wang, T.; Escobar-Wolf, R.; Oommen, T.; Lu, Z.; Kim, J.; Lundgren, P. R.; Waite, G. P.

2017-01-01

Although massive flank failure is fairly common in the evolution of volcanoes, measurements of flank movement indicative of instability are rare. Here 3-D displacements from airborne radar amplitude images derived using an amplitude image pixel offset tracking technique show that the west and southwest flanks of Pacaya Volcano in Guatemala experienced large ( 4 m), discrete landsliding that was ultimately aborted. Pixel offset tracking improved measurement recovery by nearly 50% over classic interferometric synthetic aperture radar techniques, providing unique measurements at the event. The 3-D displacement field shows that the flank moved coherently downslope along a complex failure surface involving both rotational and along-slope movement. Notably, the lack of continuous movement of the slide in the years leading up to the event emphasizes that active movement should not always be expected at volcanoes for which triggering factors (e.g., magmatic intrusions and eruptions) could precipitate sudden major flank instability.

Incorporating temporal variation in seabird telemetry data: time variant kernel density models

USGS Publications Warehouse

Gilbert, Andrew; Adams, Evan M.; Anderson, Carl; Berlin, Alicia; Bowman, Timothy D.; Connelly, Emily; Gilliland, Scott; Gray, Carrie E.; Lepage, Christine; Meattey, Dustin; Montevecchi, William; Osenkowski, Jason; Savoy, Lucas; Stenhouse, Iain; Williams, Kathryn

2015-01-01

A key component of the Mid-Atlantic Baseline Studies project was tracking the individual movements of focal marine bird species (Red-throated Loon [Gavia stellata], Northern Gannet [Morus bassanus], and Surf Scoter [Melanitta perspicillata]) through the use of satellite telemetry. This element of the project was a collaborative effort with the Department of Energy (DOE), Bureau of Ocean Energy Management (BOEM), the U.S. Fish and Wildlife Service (USFWS), and Sea Duck Joint Venture (SDJV), among other organizations. Satellite telemetry is an effective and informative tool for understanding individual animal movement patterns, allowing researchers to mark an individual once, and thereafter follow the movements of the animal in space and time. Aggregating telemetry data from multiple individuals can provide information about the spatial use and temporal movements of populations. Tracking data is three dimensional, with the first two dimensions, X and Y, ordered along the third dimension, time. GIS software has many capabilities to store, analyze and visualize the location information, but little or no support for visualizing the temporal data, and tools for processing temporal data are lacking. We explored several ways of analyzing the movement patterns using the spatiotemporal data provided by satellite tags. Here, we present the results of one promising method: time-variant kernel density analysis (Keating and Cherry, 2009). The goal of this chapter is to demonstrate new methods in spatial analysis to visualize and interpret tracking data for a large number of individual birds across time in the mid-Atlantic study area and beyond. In this chapter, we placed greater emphasis on analytical methods than on the behavior and ecology of the animals tracked. For more detailed examinations of the ecology and wintering habitat use of the focal species in the midAtlantic, see Chapters 20-22.

Do Activity Level Outcome Measures Commonly Used in Neurological Practice Assess Upper-Limb Movement Quality?

PubMed

Demers, Marika; Levin, Mindy F

2017-07-01

Movement is described in terms of task-related end point characteristics in external space and movement quality (joint rotations in body space). Assessment of upper-limb (UL) movement quality can assist therapists in designing effective treatment approaches for retraining lost motor elements and provide more detailed measurements of UL motor improvements over time. To determine the extent to which current activity level outcome measures used in neurological practice assess UL movement quality. Outcome measures assessing arm/hand function at the International Classification of Function activity level recommended by neurological clinical practice guidelines were reviewed. Measures assessing the UL as part of a general mobility assessment, those strictly evaluating body function/structure or participation, and paediatric measures were excluded. In all, 15 activity level outcome measures were identified; 9 measures assess how movement is performed by measuring either end point characteristics or movement quality. However, except for the Reaching Performance Scale for Stroke and the Motor Evaluation Scale for Upper Extremity in Stroke Patients, these measures only account for deficits indirectly by giving a partial score if movements are slower or if the person experiences difficulties. Six outcome measures neither assess any parameters related to movement quality, nor distinguish between improvements resulting from motor compensation or recovery of desired movement strategies. Current activity measures may not distinguish recovery from compensation and adequately track changes in movement quality over time. Movement quality may be incorporated into clinical assessment using observational kinematics with or without low-cost motion tracking technology.

A Herbivore Knows Its Patch: Luderick, Girella tricuspidata, Exhibit Strong Site Fidelity on Shallow Subtidal Reefs in a Temperate Marine Park

PubMed Central

Ferguson, Adrian M.; Harvey, Euan S.; Taylor, Matthew D.; Knott, Nathan A.

2013-01-01

Understanding movement patterns, habitat use and behaviour of fish is critical to determining how targeted species may respond to protection provided by “no-take” sanctuary zones within marine parks. We assessed the fine and broad scale movement patterns of an exploited herbivore, luderick (Girella tricuspidata), using acoustic telemetry to evaluate how this species may respond to protection within Jervis Bay (New South Wales, Australia). We surgically implanted fourteen fish with acoustic transmitters and actively and passively tracked individuals to determine fine and broad scale movement patterns respectively. Eight fish were actively tracked for 24 h d¯1 for 6 d (May 2011), and then intermittently over the following 30 d. Six fish were passively tracked from December 2011 to March 2012, using a fixed array of receivers deployed across rocky reefs around the perimeter of the bay. Luderick exhibited strong site fidelity on shallow subtidal reefs, tending to remain on or return consistently to the reef where they were caught and released. All eight fish actively tracked used core areas solely on their release reef, with the exception of one fish that used multiple core areas, and four of the six fish passively tracked spent between 75 to 96% of days on release reefs over the entire tracking period. Luderick did move frequently to adjacent reefs, and occasionally to more distant reefs, however consistently returned to their release reef. Luderick also exhibited predictable patterns in movement between spatially distinct daytime and night-time core use areas. Night-time core use areas were generally located in sheltered areas behind the edge of reefs. Overall, our data indicate luderick exhibit strong site fidelity on shallow subtidal reefs in Jervis Bay and suggests that this important herbivore may be likely to show a positive response to protection within the marine park. PMID:23741515

A herbivore knows its patch: luderick, Girella tricuspidata, exhibit strong site fidelity on shallow subtidal reefs in a temperate marine park.

PubMed

Ferguson, Adrian M; Harvey, Euan S; Taylor, Matthew D; Knott, Nathan A

2013-01-01

Understanding movement patterns, habitat use and behaviour of fish is critical to determining how targeted species may respond to protection provided by "no-take" sanctuary zones within marine parks. We assessed the fine and broad scale movement patterns of an exploited herbivore, luderick (Girella tricuspidata), using acoustic telemetry to evaluate how this species may respond to protection within Jervis Bay (New South Wales, Australia). We surgically implanted fourteen fish with acoustic transmitters and actively and passively tracked individuals to determine fine and broad scale movement patterns respectively. Eight fish were actively tracked for 24 h d¯(1) for 6 d (May 2011), and then intermittently over the following 30 d. Six fish were passively tracked from December 2011 to March 2012, using a fixed array of receivers deployed across rocky reefs around the perimeter of the bay. Luderick exhibited strong site fidelity on shallow subtidal reefs, tending to remain on or return consistently to the reef where they were caught and released. All eight fish actively tracked used core areas solely on their release reef, with the exception of one fish that used multiple core areas, and four of the six fish passively tracked spent between 75 to 96% of days on release reefs over the entire tracking period. Luderick did move frequently to adjacent reefs, and occasionally to more distant reefs, however consistently returned to their release reef. Luderick also exhibited predictable patterns in movement between spatially distinct daytime and night-time core use areas. Night-time core use areas were generally located in sheltered areas behind the edge of reefs. Overall, our data indicate luderick exhibit strong site fidelity on shallow subtidal reefs in Jervis Bay and suggests that this important herbivore may be likely to show a positive response to protection within the marine park.

A geometric method for computing ocular kinematics and classifying gaze events using monocular remote eye tracking in a robotic environment.

PubMed

Singh, Tarkeshwar; Perry, Christopher M; Herter, Troy M

2016-01-26

Robotic and virtual-reality systems offer tremendous potential for improving assessment and rehabilitation of neurological disorders affecting the upper extremity. A key feature of these systems is that visual stimuli are often presented within the same workspace as the hands (i.e., peripersonal space). Integrating video-based remote eye tracking with robotic and virtual-reality systems can provide an additional tool for investigating how cognitive processes influence visuomotor learning and rehabilitation of the upper extremity. However, remote eye tracking systems typically compute ocular kinematics by assuming eye movements are made in a plane with constant depth (e.g. frontal plane). When visual stimuli are presented at variable depths (e.g. transverse plane), eye movements have a vergence component that may influence reliable detection of gaze events (fixations, smooth pursuits and saccades). To our knowledge, there are no available methods to classify gaze events in the transverse plane for monocular remote eye tracking systems. Here we present a geometrical method to compute ocular kinematics from a monocular remote eye tracking system when visual stimuli are presented in the transverse plane. We then use the obtained kinematics to compute velocity-based thresholds that allow us to accurately identify onsets and offsets of fixations, saccades and smooth pursuits. Finally, we validate our algorithm by comparing the gaze events computed by the algorithm with those obtained from the eye-tracking software and manual digitization. Within the transverse plane, our algorithm reliably differentiates saccades from fixations (static visual stimuli) and smooth pursuits from saccades and fixations when visual stimuli are dynamic. The proposed methods provide advancements for examining eye movements in robotic and virtual-reality systems. Our methods can also be used with other video-based or tablet-based systems in which eye movements are performed in a peripersonal plane with variable depth.

Studying the movement behavior of benthic macroinvertebrates with automated video tracking.

PubMed

Augusiak, Jacqueline; Van den Brink, Paul J

2015-04-01

Quantifying and understanding movement is critical for a wide range of questions in basic and applied ecology. Movement ecology is also fostered by technological advances that allow automated tracking for a wide range of animal species. However, for aquatic macroinvertebrates, such detailed methods do not yet exist. We developed a video tracking method for two different species of benthic macroinvertebrates, the crawling isopod Asellus aquaticus and the swimming fresh water amphipod Gammarus pulex. We tested the effects of different light sources and marking techniques on their movement behavior to establish the possibilities and limitations of the experimental protocol and to ensure that the basic handling of test specimens would not bias conclusions drawn from movement path analyses. To demonstrate the versatility of our method, we studied the influence of varying population densities on different movement parameters related to resting behavior, directionality, and step lengths. We found that our method allows studying species with different modes of dispersal and under different conditions. For example, we found that gammarids spend more time moving at higher population densities, while asellids rest more under similar conditions. At the same time, in response to higher densities, gammarids mostly decreased average step lengths, whereas asellids did not. Gammarids, however, were also more sensitive to general handling and marking than asellids. Our protocol for marking and video tracking can be easily adopted for other species of aquatic macroinvertebrates or testing conditions, for example, presence or absence of food sources, shelter, or predator cues. Nevertheless, limitations with regard to the marking protocol, material, and a species' physical build need to be considered and tested before a wider application, particularly for swimming species. Data obtained with this approach can deepen the understanding of population dynamics on larger spatial scales and of the effects of different management strategies on a species' dispersal potential.

Studying the movement behavior of benthic macroinvertebrates with automated video tracking

PubMed Central

Augusiak, Jacqueline; Van den Brink, Paul J

2015-01-01

Quantifying and understanding movement is critical for a wide range of questions in basic and applied ecology. Movement ecology is also fostered by technological advances that allow automated tracking for a wide range of animal species. However, for aquatic macroinvertebrates, such detailed methods do not yet exist. We developed a video tracking method for two different species of benthic macroinvertebrates, the crawling isopod Asellus aquaticus and the swimming fresh water amphipod Gammarus pulex. We tested the effects of different light sources and marking techniques on their movement behavior to establish the possibilities and limitations of the experimental protocol and to ensure that the basic handling of test specimens would not bias conclusions drawn from movement path analyses. To demonstrate the versatility of our method, we studied the influence of varying population densities on different movement parameters related to resting behavior, directionality, and step lengths. We found that our method allows studying species with different modes of dispersal and under different conditions. For example, we found that gammarids spend more time moving at higher population densities, while asellids rest more under similar conditions. At the same time, in response to higher densities, gammarids mostly decreased average step lengths, whereas asellids did not. Gammarids, however, were also more sensitive to general handling and marking than asellids. Our protocol for marking and video tracking can be easily adopted for other species of aquatic macroinvertebrates or testing conditions, for example, presence or absence of food sources, shelter, or predator cues. Nevertheless, limitations with regard to the marking protocol, material, and a species’ physical build need to be considered and tested before a wider application, particularly for swimming species. Data obtained with this approach can deepen the understanding of population dynamics on larger spatial scales and of the effects of different management strategies on a species’ dispersal potential. PMID:25937901

Investigating three types of continuous auditory feedback in visuo-manual tracking.

PubMed

Boyer, Éric O; Bevilacqua, Frédéric; Susini, Patrick; Hanneton, Sylvain

2017-03-01

The use of continuous auditory feedback for motor control and learning is still understudied and deserves more attention regarding fundamental mechanisms and applications. This paper presents the results of three experiments studying the contribution of task-, error-, and user-related sonification to visuo-manual tracking and assessing its benefits on sensorimotor learning. First results show that sonification can help decreasing the tracking error, as well as increasing the energy in participant's movement. In the second experiment, when alternating feedback presence, the user-related sonification did not show feedback dependency effects, contrary to the error and task-related feedback. In the third experiment, a reduced exposure of 50% diminished the positive effect of sonification on performance, whereas the increase of the average energy with sound was still significant. In a retention test performed on the next day without auditory feedback, movement energy was still superior for the groups previously trained with the feedback. Although performance was not affected by sound, a learning effect was measurable in both sessions and the user-related group improved its performance also in the retention test. These results confirm that a continuous auditory feedback can be beneficial for movement training and also show an interesting effect of sonification on movement energy. User-related sonification can prevent feedback dependency and increase retention. Consequently, sonification of the user's own motion appears as a promising solution to support movement learning with interactive feedback.

Tracking the Eye Movement of Four Years Old Children Learning Chinese Words.

PubMed

Lin, Dan; Chen, Guangyao; Liu, Yingyi; Liu, Jiaxin; Pan, Jue; Mo, Lei

2018-02-01

Storybook reading is the major source of literacy exposure for beginning readers. The present study tracked 4-year-old Chinese children's eye movements while they were reading simulated storybook pages. Their eye-movement patterns were examined in relation to their word learning gains. The same reading list, consisting of 20 two-character Chinese words, was used in the pretest, 5-min eye-tracking learning session, and posttest. Additionally, visual spatial skill and phonological awareness were assessed in the pretest as cognitive controls. The results showed that the children's attention was attracted quickly by pictures, on which their attention was focused most, with only 13% of the time looking at words. Moreover, significant learning gains in word reading were observed, from the pretest to posttest, from 5-min exposure to simulated storybook pages with words, picture and pronunciation of two-character words present. Furthermore, the children's attention to words significantly predicted posttest reading beyond socioeconomic status, age, visual spatial skill, phonological awareness and pretest reading performance. This eye-movement evidence of storybook reading by children as young as four years, reading a non-alphabetic script (i.e., Chinese), has demonstrated exciting findings that children can learn words effectively with minimal exposure and little instruction; these findings suggest that learning to read requires attention to the basic words itself. The study contributes to our understanding of early reading acquisition with eye-movement evidence from beginning readers.

The Head Tracks and Gaze Predicts: How the World’s Best Batters Hit a Ball

PubMed Central

Mann, David L.; Spratford, Wayne; Abernethy, Bruce

2013-01-01

Hitters in fast ball-sports do not align their gaze with the ball throughout ball-flight; rather, they use predictive eye movement strategies that contribute towards their level of interceptive skill. Existing studies claim that (i) baseball and cricket batters cannot track the ball because it moves too quickly to be tracked by the eyes, and that consequently (ii) batters do not – and possibly cannot – watch the ball at the moment they hit it. However, to date no studies have examined the gaze of truly elite batters. We examined the eye and head movements of two of the world’s best cricket batters and found both claims do not apply to these batters. Remarkably, the batters coupled the rotation of their head to the movement of the ball, ensuring the ball remained in a consistent direction relative to their head. To this end, the ball could be followed if the batters simply moved their head and kept their eyes still. Instead of doing so, we show the elite batters used distinctive eye movement strategies, usually relying on two predictive saccades to anticipate (i) the location of ball-bounce, and (ii) the location of bat-ball contact, ensuring they could direct their gaze towards the ball as they hit it. These specific head and eye movement strategies play important functional roles in contributing towards interceptive expertise. PMID:23516460

Movement trajectories and habitat partitioning of small mammals in logged and unlogged rain forests on Borneo.

PubMed

Wells, Konstans; Pfeiffer, Martin; Lakim, Maklarin B; Kalko, Elisabeth K V

2006-09-01

1. Non-volant animals in tropical rain forests differ in their ability to exploit the habitat above the forest floor and also in their response to habitat variability. It is predicted that specific movement trajectories are determined both by intrinsic factors such as ecological specialization, morphology and body size and by structural features of the surrounding habitat such as undergrowth and availability of supportive structures. 2. We applied spool-and-line tracking in order to describe movement trajectories and habitat segregation of eight species of small mammals from an assemblage of Muridae, Tupaiidae and Sciuridae in the rain forest of Borneo where we followed a total of 13,525 m path. We also analysed specific changes in the movement patterns of the small mammals in relation to habitat stratification between logged and unlogged forests. Variables related to climbing activity of the tracked species as well as the supportive structures of the vegetation and undergrowth density were measured along their tracks. 3. Movement patterns of the small mammals differed significantly between species. Most similarities were found in congeneric species that converged strongly in body size and morphology. All species were affected in their movement patterns by the altered forest structure in logged forests with most differences found in Leopoldamys sabanus. However, the large proportions of short step lengths found in all species for both forest types and similar path tortuosity suggest that the main movement strategies of the small mammals were not influenced by logging but comprised generally a response to the heterogeneous habitat as opposed to random movement strategies predicted for homogeneous environments. 4. Overall shifts in microhabitat use showed no coherent trend among species. Multivariate (principal component) analysis revealed contrasting trends for convergent species, in particular for Maxomys rajah and M. surifer as well as for Tupaia longipes and T. tana, suggesting that each species was uniquely affected in its movement trajectories by a multiple set of environmental and intrinsic features.

Motion correction for improved estimation of heart rate using a visual spectrum camera

NASA Astrophysics Data System (ADS)

Tarbox, Elizabeth A.; Rios, Christian; Kaur, Balvinder; Meyer, Shaun; Hirt, Lauren; Tran, Vy; Scott, Kaitlyn; Ikonomidou, Vasiliki

2017-05-01

Heart rate measurement using a visual spectrum recording of the face has drawn interest over the last few years as a technology that can have various health and security applications. In our previous work, we have shown that it is possible to estimate the heart beat timing accurately enough to perform heart rate variability analysis for contactless stress detection. However, a major confounding factor in this approach is the presence of movement, which can interfere with the measurements. To mitigate the effects of movement, in this work we propose the use of face detection and tracking based on the Karhunen-Loewe algorithm in order to counteract measurement errors introduced by normal subject motion, as expected during a common seated conversation setting. We analyze the requirements on image acquisition for the algorithm to work, and its performance under different ranges of motion, changes of distance to the camera, as well and the effect of illumination changes due to different positioning with respect to light sources on the acquired signal. Our results suggest that the effect of face tracking on visual-spectrum based cardiac signal estimation depends on the amplitude of the motion. While for larger-scale conversation-induced motion it can significantly improve estimation accuracy, with smaller-scale movements, such as the ones caused by breathing or talking without major movement errors in facial tracking may interfere with signal estimation. Overall, employing facial tracking is a crucial step in adapting this technology to real-life situations with satisfactory results.

A new method for discovering behavior patterns among animal movements

USGS Publications Warehouse

Wang, Y.; Luo, Ze; Takekawa, John Y.; Prosser, Diann J.; Xiong, Y.; Newman, S.; Xiao, X.; Batbayar, N.; Spragens, Kyle A.; Balachandran, S.; Yan, B.

2016-01-01

Advanced satellite tracking technologies enable biologists to track animal movements at fine spatial and temporal scales. The resultant data present opportunities and challenges for understanding animal behavioral mechanisms. In this paper, we develop a new method to elucidate animal movement patterns from tracking data. Here, we propose the notion of continuous behavior patterns as a concise representation of popular migration routes and underlying sequential behaviors during migration. Each stage in the pattern is characterized in terms of space (i.e., the places traversed during movements) and time (i.e. the time spent in those places); that is, the behavioral state corresponding to a stage is inferred according to the spatiotemporal and sequential context. Hence, the pattern may be interpreted predictably. We develop a candidate generation and refinement framework to derive all continuous behavior patterns from raw trajectories. In the framework, we first define the representative spots to denote the underlying potential behavioral states that are extracted from individual trajectories according to the similarity of relaxed continuous locations in certain distinct time intervals. We determine the common behaviors of multiple individuals according to the spatiotemporal proximity of representative spots and apply a projection-based extension approach to generate candidate sequential behavior sequences as candidate patterns. Finally, the candidate generation procedure is combined with a refinement procedure to derive continuous behavior patterns. We apply an ordered processing strategy to accelerate candidate refinement. The proposed patterns and discovery framework are evaluated through conceptual experiments on both real GPS-tracking and large synthetic datasets.

A new method for discovering behavior patterns among animal movements.

PubMed

Wang, Yuwei; Luo, Ze; Takekawa, John; Prosser, Diann; Xiong, Yan; Newman, Scott; Xiao, Xiangming; Batbayar, Nyambayar; Spragens, Kyle; Balachandran, Sivananinthaperumal; Yan, Baoping

Advanced satellite tracking technologies enable biologists to track animal movements at fine spatial and temporal scales. The resultant data present opportunities and challenges for understanding animal behavioral mechanisms. In this paper, we develop a new method to elucidate animal movement patterns from tracking data. Here, we propose the notion of continuous behavior patterns as a concise representation of popular migration routes and underlying sequential behaviors during migration. Each stage in the pattern is characterized in terms of space (i.e., the places traversed during movements) and time (i.e. the time spent in those places); that is, the behavioral state corresponding to a stage is inferred according to the spatiotemporal and sequential context. Hence, the pattern may be interpreted predictably. We develop a candidate generation and refinement framework to derive all continuous behavior patterns from raw trajectories. In the framework, we first define the representative spots to denote the underlying potential behavioral states that are extracted from individual trajectories according to the similarity of relaxed continuous locations in certain distinct time intervals. We determine the common behaviors of multiple individuals according to the spatiotemporal proximity of representative spots and apply a projection-based extension approach to generate candidate sequential behavior sequences as candidate patterns. Finally, the candidate generation procedure is combined with a refinement procedure to derive continuous behavior patterns. We apply an ordered processing strategy to accelerate candidate refinement. The proposed patterns and discovery framework are evaluated through conceptual experiments on both real GPS-tracking and large synthetic datasets.

A new method for discovering behavior patterns among animal movements

PubMed Central

Wang, Yuwei; Luo, Ze; Takekawa, John; Prosser, Diann; Xiong, Yan; Newman, Scott; Xiao, Xiangming; Batbayar, Nyambayar; Spragens, Kyle; Balachandran, Sivananinthaperumal; Yan, Baoping

2016-01-01

Advanced satellite tracking technologies enable biologists to track animal movements at fine spatial and temporal scales. The resultant data present opportunities and challenges for understanding animal behavioral mechanisms. In this paper, we develop a new method to elucidate animal movement patterns from tracking data. Here, we propose the notion of continuous behavior patterns as a concise representation of popular migration routes and underlying sequential behaviors during migration. Each stage in the pattern is characterized in terms of space (i.e., the places traversed during movements) and time (i.e. the time spent in those places); that is, the behavioral state corresponding to a stage is inferred according to the spatiotemporal and sequential context. Hence, the pattern may be interpreted predictably. We develop a candidate generation and refinement framework to derive all continuous behavior patterns from raw trajectories. In the framework, we first define the representative spots to denote the underlying potential behavioral states that are extracted from individual trajectories according to the similarity of relaxed continuous locations in certain distinct time intervals. We determine the common behaviors of multiple individuals according to the spatiotemporal proximity of representative spots and apply a projection-based extension approach to generate candidate sequential behavior sequences as candidate patterns. Finally, the candidate generation procedure is combined with a refinement procedure to derive continuous behavior patterns. We apply an ordered processing strategy to accelerate candidate refinement. The proposed patterns and discovery framework are evaluated through conceptual experiments on both real GPS-tracking and large synthetic datasets. PMID:27217810

The virtual craniofacial patient: 3D jaw modeling and animation.

PubMed

Enciso, Reyes; Memon, Ahmed; Fidaleo, Douglas A; Neumann, Ulrich; Mah, James

2003-01-01

In this paper, we present new developments in the area of 3D human jaw modeling and animation. CT (Computed Tomography) scans have traditionally been used to evaluate patients with dental implants, assess tumors, cysts, fractures and surgical procedures. More recently this data has been utilized to generate models. Researchers have reported semi-automatic techniques to segment and model the human jaw from CT images and manually segment the jaw from MRI images. Recently opto-electronic and ultrasonic-based systems (JMA from Zebris) have been developed to record mandibular position and movement. In this research project we introduce: (1) automatic patient-specific three-dimensional jaw modeling from CT data and (2) three-dimensional jaw motion simulation using jaw tracking data from the JMA system (Zebris).

Inferring animal densities from tracking data using Markov chains.

PubMed

Whitehead, Hal; Jonsen, Ian D

2013-01-01

The distributions and relative densities of species are keys to ecology. Large amounts of tracking data are being collected on a wide variety of animal species using several methods, especially electronic tags that record location. These tracking data are effectively used for many purposes, but generally provide biased measures of distribution, because the starts of the tracks are not randomly distributed among the locations used by the animals. We introduce a simple Markov-chain method that produces unbiased measures of relative density from tracking data. The density estimates can be over a geographical grid, and/or relative to environmental measures. The method assumes that the tracked animals are a random subset of the population in respect to how they move through the habitat cells, and that the movements of the animals among the habitat cells form a time-homogenous Markov chain. We illustrate the method using simulated data as well as real data on the movements of sperm whales. The simulations illustrate the bias introduced when the initial tracking locations are not randomly distributed, as well as the lack of bias when the Markov method is used. We believe that this method will be important in giving unbiased estimates of density from the growing corpus of animal tracking data.

THE KINEMATICS OF PRIMATE MIDFOOT FLEXIBILITY

PubMed Central

Greiner, Thomas M.; Ball, Kevin A.

2015-01-01

This study describes a unique assessment of primate intrinsic foot joint kinematics based upon bone pin rigid cluster tracking. It challenges the assumption that human evolution resulted in a reduction of midfoot flexibility, which has been identified in other primates as the “midtarsal break.” Rigid cluster pins were inserted into the foot bones of human, chimpanzee, baboon and macaque cadavers. The positions of these bone pins were monitored during a plantarflexion-dorsiflexion movement cycle. Analysis resolved flexion-extension movement patterns and the associated orientation of rotational axes for the talonavicular, calcaneocuboid and lateral cubometatarsal joints. Results show that midfoot flexibility occurs primarily at the talonavicular and cubometatarsal joints. The rotational magnitudes are roughly similar between humans and chimps. There is also a similarity among evaluated primates in the observed rotations of the lateral cubometatarsal joint, but there was much greater rotation observed for the talonavicular joint, which may serve to differentiate monkeys from the hominines. It appears that the capability for a midtarsal break is present within the human foot. A consideration of the joint axes shows that the medial and lateral joints have opposing orientations, which has been associated with a rigid locking mechanism in the human foot. However, the potential for this same mechanism also appears in the chimpanzee foot. These findings demonstrate a functional similarity within the midfoot of the hominines. Therefore, the kinematic capabilities and restrictions for the skeletal linkages of the human foot may not be as unique as has been previously suggested. PMID:25234343

Low relative error in consumer-grade GPS units make them ideal for measuring small-scale animal movement patterns

PubMed Central

Severns, Paul M.

2015-01-01

Consumer-grade GPS units are a staple of modern field ecology, but the relatively large error radii reported by manufacturers (up to 10 m) ostensibly precludes their utility in measuring fine-scale movement of small animals such as insects. Here we demonstrate that for data collected at fine spatio-temporal scales, these devices can produce exceptionally accurate data on step-length and movement patterns of small animals. With an understanding of the properties of GPS error and how it arises, it is possible, using a simple field protocol, to use consumer grade GPS units to collect step-length data for the movement of small animals that introduces a median error as small as 11 cm. These small error rates were measured in controlled observations of real butterfly movement. Similar conclusions were reached using a ground-truth test track prepared with a field tape and compass and subsequently measured 20 times using the same methodology as the butterfly tracking. Median error in the ground-truth track was slightly higher than the field data, mostly between 20 and 30 cm, but even for the smallest ground-truth step (70 cm), this is still a signal-to-noise ratio of 3:1, and for steps of 3 m or more, the ratio is greater than 10:1. Such small errors relative to the movements being measured make these inexpensive units useful for measuring insect and other small animal movements on small to intermediate scales with budgets orders of magnitude lower than survey-grade units used in past studies. As an additional advantage, these units are simpler to operate, and insect or other small animal trackways can be collected more quickly than either survey-grade units or more traditional ruler/gird approaches. PMID:26312190

Low relative error in consumer-grade GPS units make them ideal for measuring small-scale animal movement patterns.

PubMed

Breed, Greg A; Severns, Paul M

2015-01-01

Consumer-grade GPS units are a staple of modern field ecology, but the relatively large error radii reported by manufacturers (up to 10 m) ostensibly precludes their utility in measuring fine-scale movement of small animals such as insects. Here we demonstrate that for data collected at fine spatio-temporal scales, these devices can produce exceptionally accurate data on step-length and movement patterns of small animals. With an understanding of the properties of GPS error and how it arises, it is possible, using a simple field protocol, to use consumer grade GPS units to collect step-length data for the movement of small animals that introduces a median error as small as 11 cm. These small error rates were measured in controlled observations of real butterfly movement. Similar conclusions were reached using a ground-truth test track prepared with a field tape and compass and subsequently measured 20 times using the same methodology as the butterfly tracking. Median error in the ground-truth track was slightly higher than the field data, mostly between 20 and 30 cm, but even for the smallest ground-truth step (70 cm), this is still a signal-to-noise ratio of 3:1, and for steps of 3 m or more, the ratio is greater than 10:1. Such small errors relative to the movements being measured make these inexpensive units useful for measuring insect and other small animal movements on small to intermediate scales with budgets orders of magnitude lower than survey-grade units used in past studies. As an additional advantage, these units are simpler to operate, and insect or other small animal trackways can be collected more quickly than either survey-grade units or more traditional ruler/gird approaches.

Tracking Movements of Individual Anoplophora glabripennis (Coleoptera: Cerambycidae) Adults: Application of Harmonic Radar

Treesearch

David W. Williams; Guohong Li; Ruitong Gao

2004-01-01

Movements of 55 Anoplophora glabripennis (Motschulsky) adults were monitored on 200 willow trees, Salix babylonica L., at a site appx. 80 km southeast of Beijing, China, for 9-14 d in an individual mark-recapture study using harmonic radar. The average movement distance was appx. 14 m, with many beetles not moving at all and others moving >90 m. The rate of movement...

Single-organelle tracking by two-photon conversion

NASA Astrophysics Data System (ADS)

Watanabe, Wataru; Shimada, Tomoko; Matsunaga, Sachihiro; Kurihara, Daisuke; Fukui, Kiichi; Shin-Ichi Arimura, Shin-Ichi; Tsutsumi, Nobuhiro; Isobe, Keisuke; Itoh, Kazuyoshi

2007-03-01

Spatial and temporal information about intracellular objects and their dynamics within a living cell are essential for dynamic analysis of such objects in cell biology. A specific intracellular object can be discriminated by photoactivatable fluorescent proteins that exhibit pronounced light-induced spectral changes. Here, we report on selective labeling and tracking of a single organelle by using two-photon conversion of a photoconvertible fluorescent protein with near-infrared femtosecond laser pulses. We performed selective labeling of a single mitochondrion in a living tobacco BY-2 cell using two-photon photoconversion of Kaede. Using this technique, we demonstrated that, in plants, the directed movement of individual mitochondria along the cytoskeletons was mediated by actin filaments, whereas microtubules were not required for the movement of mitochondria. This single-organelle labeling technique enabled us to track the dynamics of a single organelle, revealing the mechanisms involved in organelle dynamics. The technique has potential application in direct tracking of selective cellular and intracellular structures.

Genetics Home Reference: horizontal gaze palsy with progressive scoliosis

MedlinePlus

... to track moving objects. Up-and-down (vertical) eye movements are typically normal. In people with HGPPS , an ... the brainstem is the underlying cause of the eye movement abnormalities associated with the disorder. The cause of ...

Experimental Evaluation of UWB Indoor Positioning for Sport Postures

PubMed Central

Defraye, Jense; Steendam, Heidi; Gerlo, Joeri; De Clercq, Dirk; De Poorter, Eli

2018-01-01

Radio frequency (RF)-based indoor positioning systems (IPSs) use wireless technologies (including Wi-Fi, Zigbee, Bluetooth, and ultra-wide band (UWB)) to estimate the location of persons in areas where no Global Positioning System (GPS) reception is available, for example in indoor stadiums or sports halls. Of the above-mentioned forms of radio frequency (RF) technology, UWB is considered one of the most accurate approaches because it can provide positioning estimates with centimeter-level accuracy. However, it is not yet known whether UWB can also offer such accurate position estimates during strenuous dynamic activities in which moves are characterized by fast changes in direction and velocity. To answer this question, this paper investigates the capabilities of UWB indoor localization systems for tracking athletes during their complex (and most of the time unpredictable) movements. To this end, we analyze the impact of on-body tag placement locations and human movement patterns on localization accuracy and communication reliability. Moreover, two localization algorithms (particle filter and Kalman filter) with different optimizations (bias removal, non-line-of-sight (NLoS) detection, and path determination) are implemented. It is shown that although the optimal choice of optimization depends on the type of movement patterns, some of the improvements can reduce the localization error by up to 31%. Overall, depending on the selected optimization and on-body tag placement, our algorithms show good results in terms of positioning accuracy, with average errors in position estimates of 20 cm. This makes UWB a suitable approach for tracking dynamic athletic activities. PMID:29315267

A portable multi-channel recording system for analysis of acceleration and angular velocity in six dimension.

PubMed

Yamashita, M; Yamashita, A; Ishii, T; Naruo, Y; Nagatomo, M

1998-11-01

A portable recording system was developed for analysis of more than three analog signals collected in field works. Stereo audio recorder, available as consumer products, was made use for a core cornponent of the system. For the two tracks of recording, a multiplexed analog signal is stored on one track, and reference code on the other track. The reference code indicates the start of one cycle for multiplexing and swiching point of each channel. Multiplexed signal is playbacked and decoded with a reference of the code to reconstruct original profiles of the signal. Since commercial stereo recorders have cut DC component off, a fixed reference voltage is inserted in the sequence of multiplexing. Change of voltage at switching from the reference to the data channel is measured from playbacked signal to get the original data with its DC component. Movement of vehicles and human head were analyzed by the system. It was verified to be capable to record and analyze multi-channel signal at a sampling rate more than 10Hz.

Gaussian mixture model based identification of arterial wall movement for computation of distension waveform.

PubMed

Patil, Ravindra B; Krishnamoorthy, P; Sethuraman, Shriram

2015-01-01

This work proposes a novel Gaussian Mixture Model (GMM) based approach for accurate tracking of the arterial wall and subsequent computation of the distension waveform using Radio Frequency (RF) ultrasound signal. The approach was evaluated on ultrasound RF data acquired using a prototype ultrasound system from an artery mimicking flow phantom. The effectiveness of the proposed algorithm is demonstrated by comparing with existing wall tracking algorithms. The experimental results show that the proposed method provides 20% reduction in the error margin compared to the existing approaches in tracking the arterial wall movement. This approach coupled with ultrasound system can be used to estimate the arterial compliance parameters required for screening of cardiovascular related disorders.

Accuracy of Tracking Forest Machines with GPS

Treesearch

M.W. Veal; S.E. Taylor; T.P. McDonald; D.K. McLemore; M.R. Dunn

2001-01-01

This paper describes the results of a study that measured the accuracy of using GPS to track movement offorest machines. Two different commercially available GPS receivers (Trimble ProXR and GeoExplorer II) were used to track wheeled skidders under three different canopy conditions at two different vehicle speeds. Dynamic GPS data were compared to position data...

Human tracking over camera networks: a review

NASA Astrophysics Data System (ADS)

Hou, Li; Wan, Wanggen; Hwang, Jenq-Neng; Muhammad, Rizwan; Yang, Mingyang; Han, Kang

2017-12-01

In recent years, automated human tracking over camera networks is getting essential for video surveillance. The tasks of tracking human over camera networks are not only inherently challenging due to changing human appearance, but also have enormous potentials for a wide range of practical applications, ranging from security surveillance to retail and health care. This review paper surveys the most widely used techniques and recent advances for human tracking over camera networks. Two important functional modules for the human tracking over camera networks are addressed, including human tracking within a camera and human tracking across non-overlapping cameras. The core techniques of human tracking within a camera are discussed based on two aspects, i.e., generative trackers and discriminative trackers. The core techniques of human tracking across non-overlapping cameras are then discussed based on the aspects of human re-identification, camera-link model-based tracking and graph model-based tracking. Our survey aims to address existing problems, challenges, and future research directions based on the analyses of the current progress made toward human tracking techniques over camera networks.

Directional errors of movements and their correction in a discrete tracking task. [pilot reaction time and sensorimotor performance

NASA Technical Reports Server (NTRS)

Jaeger, R. J.; Agarwal, G. C.; Gottlieb, G. L.

1978-01-01

Subjects can correct their own errors of movement more quickly than they can react to external stimuli by using three general categories of feedback: (1) knowledge of results, primarily visually mediated; (2) proprioceptive or kinaesthetic such as from muscle spindles and joint receptors, and (3) corollary discharge or efference copy within the central nervous system. The effects of these feedbacks on simple reaction time, choice reaction time, and error correction time were studied in four normal human subjects. The movement used was plantarflexion and dorsiflexion of the ankle joint. The feedback loops were modified, by changing the sign of the visual display to alter the subject's perception of results, and by applying vibration at 100 Hz simultaneously to both the agonist and antagonist muscles of the ankle joint. The central processing was interfered with when the subjects were given moderate doses of alcohol (blood alcohol concentration levels of up to 0.07%). Vibration and alcohol increase both the simple and choice reaction times but not the error correction time.

Evaluation of a video-based head motion tracking system for dedicated brain PET

NASA Astrophysics Data System (ADS)

Anishchenko, S.; Beylin, D.; Stepanov, P.; Stepanov, A.; Weinberg, I. N.; Schaeffer, S.; Zavarzin, V.; Shaposhnikov, D.; Smith, M. F.

2015-03-01

Unintentional head motion during Positron Emission Tomography (PET) data acquisition can degrade PET image quality and lead to artifacts. Poor patient compliance, head tremor, and coughing are examples of movement sources. Head motion due to patient non-compliance can be an issue with the rise of amyloid brain PET in dementia patients. To preserve PET image resolution and quantitative accuracy, head motion can be tracked and corrected in the image reconstruction algorithm. While fiducial markers can be used, a contactless approach is preferable. A video-based head motion tracking system for a dedicated portable brain PET scanner was developed. Four wide-angle cameras organized in two stereo pairs are used for capturing video of the patient's head during the PET data acquisition. Facial points are automatically tracked and used to determine the six degree of freedom head pose as a function of time. The presented work evaluated the newly designed tracking system using a head phantom and a moving American College of Radiology (ACR) phantom. The mean video-tracking error was 0.99±0.90 mm relative to the magnetic tracking device used as ground truth. Qualitative evaluation with the ACR phantom shows the advantage of the motion tracking application. The developed system is able to perform tracking with accuracy close to millimeter and can help to preserve resolution of brain PET images in presence of movements.

Dissociable Frontal Controls during Visible and Memory-guided Eye-Tracking of Moving Targets

PubMed Central

Ding, Jinhong; Powell, David; Jiang, Yang

2009-01-01

When tracking visible or occluded moving targets, several frontal regions including the frontal eye fields (FEF), dorsal-lateral prefrontal cortex (DLPFC), and Anterior Cingulate Cortex (ACC) are involved in smooth pursuit eye movements (SPEM). To investigate how these areas play different roles in predicting future locations of moving targets, twelve healthy college students participated in a smooth pursuit task of visual and occluded targets. Their eye movements and brain responses measured by event-related functional MRI were simultaneously recorded. Our results show that different visual cues resulted in time discrepancies between physical and estimated pursuit time only when the moving dot was occluded. Visible phase velocity gain was higher than that of occlusion phase. We found bilateral FEF association with eye-movement whether moving targets are visible or occluded. However, the DLPFC and ACC showed increased activity when tracking and predicting locations of occluded moving targets, and were suppressed during smooth pursuit of visible targets. When visual cues were increasingly available, less activation in the DLPFC and the ACC was observed. Additionally, there was a significant hemisphere effect in DLPFC, where right DLPFC showed significantly increased responses over left when pursuing occluded moving targets. Correlation results revealed that DLPFC, the right DLPFC in particular, communicates more with FEF during tracking of occluded moving targets (from memory). The ACC modulates FEF more during tracking of visible targets (likely related to visual attention). Our results suggest that DLPFC and ACC modulate FEF and cortical networks differentially during visible and memory-guided eye tracking of moving targets. PMID:19434603

Inertial Movements of the Iris as the Origin of Postsaccadic Oscillations.

PubMed

Bouzat, S; Freije, M L; Frapiccini, A L; Gasaneo, G

2018-04-27

Recent studies on the human eye indicate that the pupil moves inside the eyeball due to deformations of the iris. Here we show that this phenomenon can be originated by inertial forces undergone by the iris during the rotation of the eyeball. Moreover, these forces affect the iris in such a way that the pupil behaves effectively as a massive particle. To show this, we develop a model based on the Newton equation on the noninertial reference frame of the eyeball. The model allows us to reproduce and interpret several important findings of recent eye-tracking experiments on saccadic movements. In particular, we get correct results for the dependence of the amplitude and period of the postsaccadic oscillations on the saccade size and also for the peak velocity. The model developed may serve as a tool for characterizing eye properties of individuals.

3D for the people: multi-camera motion capture in the field with consumer-grade cameras and open source software

PubMed Central

Evangelista, Dennis J.; Ray, Dylan D.; Hedrick, Tyson L.

2016-01-01

ABSTRACT Ecological, behavioral and biomechanical studies often need to quantify animal movement and behavior in three dimensions. In laboratory studies, a common tool to accomplish these measurements is the use of multiple, calibrated high-speed cameras. Until very recently, the complexity, weight and cost of such cameras have made their deployment in field situations risky; furthermore, such cameras are not affordable to many researchers. Here, we show how inexpensive, consumer-grade cameras can adequately accomplish these measurements both within the laboratory and in the field. Combined with our methods and open source software, the availability of inexpensive, portable and rugged cameras will open up new areas of biological study by providing precise 3D tracking and quantification of animal and human movement to researchers in a wide variety of field and laboratory contexts. PMID:27444791

Inertial Movements of the Iris as the Origin of Postsaccadic Oscillations

NASA Astrophysics Data System (ADS)

Bouzat, S.; Freije, M. L.; Frapiccini, A. L.; Gasaneo, G.

2018-04-01

Recent studies on the human eye indicate that the pupil moves inside the eyeball due to deformations of the iris. Here we show that this phenomenon can be originated by inertial forces undergone by the iris during the rotation of the eyeball. Moreover, these forces affect the iris in such a way that the pupil behaves effectively as a massive particle. To show this, we develop a model based on the Newton equation on the noninertial reference frame of the eyeball. The model allows us to reproduce and interpret several important findings of recent eye-tracking experiments on saccadic movements. In particular, we get correct results for the dependence of the amplitude and period of the postsaccadic oscillations on the saccade size and also for the peak velocity. The model developed may serve as a tool for characterizing eye properties of individuals.

Factors influencing young chimpanzees' (Pan troglodytes) recognition of attention.

PubMed

Povinelli, D J; Eddy, T J

1996-12-01

By 2 1/2 years of age, human infants appear to understand how others are connected to the external world through the mental state of attention and also appear to understand the specific role that the eyes play in deploying this attention. Previous research with chimpanzees suggests that, although they track the gaze of others, they may simultaneously be unaware of the underlying state of attention behind gaze. In a series of 3 experiments, the investigators systematically explored how the presence of eyes, direct eye contact, and head orientation and movement affected young chimpanzees' choice of 2 experimenters from whom to request food. The results indicate that young chimpanzees may be selectively attached to other organisms making direct eye contact with them or engaged in postures or movements that indicate attention, even though they may not appreciate the underlying mentalistic significance of these behaviors.

Learning gestures for customizable human-computer interaction in the operating room.

PubMed

Schwarz, Loren Arthur; Bigdelou, Ali; Navab, Nassir

2011-01-01

Interaction with computer-based medical devices in the operating room is often challenging for surgeons due to sterility requirements and the complexity of interventional procedures. Typical solutions, such as delegating the interaction task to an assistant, can be inefficient. We propose a method for gesture-based interaction in the operating room that surgeons can customize to personal requirements and interventional workflow. Given training examples for each desired gesture, our system learns low-dimensional manifold models that enable recognizing gestures and tracking particular poses for fine-grained control. By capturing the surgeon's movements with a few wireless body-worn inertial sensors, we avoid issues of camera-based systems, such as sensitivity to illumination and occlusions. Using a component-based framework implementation, our method can easily be connected to different medical devices. Our experiments show that the approach is able to robustly recognize learned gestures and to distinguish these from other movements.

Assessing delay and lag in sagittal trunk control using a tracking task.

PubMed

Reeves, N Peter; Luis, Abraham; Chan, Elizabeth C; Sal Y Rosas, Victor G; Tanaka, Martin L

2018-05-17

Slower trunk muscle responses are linked to back pain and injury. Unfortunately, clinical assessments of spine function do not objectively evaluate this important attribute, which reflects speed of trunk control. Speed of trunk control can be parsed into two components: (1) delay, the time it takes to initiate a movement, and (2) lag, the time it takes to execute a movement once initiated. The goal of this study is to demonstrate a new approach to assess delay and lag in trunk control using a simple tracking task. Ten healthy subjects performed four blocks of six trials of trunk tracking in the sagittal plane. Delay and lag were estimated by modeling trunk control for predictable and unpredictable (control mode) trunk movements in flexion and extension (control direction) at movement amplitudes of 2°, 4°, and 6° (control amplitude). The main effect of control mode, direction, and amplitude of movement were compared between trial blocks to assess secondary influencers (e.g., fatigue). Only control mode was consistent across trial blocks with predictable movements being faster than unpredictable for both delay and lag. Control direction and amplitude effects on delay and lag were consistent across the first two trial blocks and less consistent in later blocks. Given the heterogeneity in the presentation of back pain, clinical assessment of trunk control should include different control modes, directions, and amplitudes. To reduce testing time and the influence of fatigue, we recommend six trials to assess trunk control. Copyright © 2018 Elsevier Ltd. All rights reserved.

Spatial and temporal movement dynamics of brook Salvelinus fontinalis and brown trout Salmo trutta

USGS Publications Warehouse

Davis, L.A.; Wagner, Tyler; Barton, Meredith L.

2015-01-01

Native eastern brook trout Salvelinus fontinalis and naturalized brown trout Salmo trutta occur sympatrically in many streams across the brook trout’s native range in the eastern United States. Understanding within- among-species variability in movement, including correlates of movement, has implications for management and conservation. We radio tracked 55 brook trout and 45 brown trout in five streams in a north-central Pennsylvania, USA watershed to quantify the movement of brook trout and brown trout during the fall and early winter to (1) evaluate the late-summer, early winter movement patterns of brook trout and brown trout, (2) determine correlates of movement and if movement patterns varied between brook trout and brown trout, and (3) evaluate genetic diversity of brook trout within and among study streams, and relate findings to telemetry-based observations of movement. Average total movement was greater for brown trout (mean ± SD = 2,924 ± 4,187 m) than for brook trout (mean ± SD = 1,769 ± 2,194 m). Although there was a large amount of among-fish variability in the movement of both species, the majority of movement coincided with the onset of the spawning season, and a threshold effect was detected between stream flow and movement: where movement increased abruptly for both species during positive flow events. Microsatellite analysis of brook trout revealed consistent findings to those found using radio-tracking, indicating a moderate to high degree of gene flow among brook trout populations. Seasonal movement patterns and the potential for relatively large movements of brook and brown trout highlight the importance of considering stream connectivity when restoring and protecting fish populations and their habitats.

A minimum attention control law for ball catching.

PubMed

Jang, Cheongjae; Lee, Jee-eun; Lee, Sohee; Park, F C

2015-10-06

Digital implementations of control laws typically involve discretization with respect to both time and space, and a control law that can achieve a task at coarser levels of discretization can be said to require less control attention, and also reduced implementation costs. One means of quantitatively capturing the attention of a control law is to measure the rate of change of the control with respect to changes in state and time. In this paper we present an attention-minimizing control law for ball catching and other target tracking tasks based on Brockett's attention criterion. We first highlight the connections between this attention criterion and some well-known principles from human motor control. Under the assumption that the optimal control law is the sum of a linear time-varying feedback term and a time-varying feedforward term, we derive an LQR-based minimum attention tracking control law that is stable, and obtained efficiently via a finite-dimensional optimization over the symmetric positive-definite matrices. Taking ball catching as our primary task, we perform numerical experiments comparing the performance of the various control strategies examined in the paper. Consistent with prevailing theories about human ball catching, our results exhibit several familiar features, e.g., the transition from open-loop to closed-loop control during the catching movement, and improved robustness to spatiotemporal discretization. The presented control laws are applicable to more general tracking problems that are subject to limited communication resources.

Accounting for direction and speed of eye motion in planning visually guided manual tracking.

PubMed

Leclercq, Guillaume; Blohm, Gunnar; Lefèvre, Philippe

2013-10-01

Accurate motor planning in a dynamic environment is a critical skill for humans because we are often required to react quickly and adequately to the visual motion of objects. Moreover, we are often in motion ourselves, and this complicates motor planning. Indeed, the retinal and spatial motions of an object are different because of the retinal motion component induced by self-motion. Many studies have investigated motion perception during smooth pursuit and concluded that eye velocity is partially taken into account by the brain. Here we investigate whether the eye velocity during ongoing smooth pursuit is taken into account for the planning of visually guided manual tracking. We had 10 human participants manually track a target while in steady-state smooth pursuit toward another target such that the difference between the retinal and spatial target motion directions could be large, depending on both the direction and the speed of the eye. We used a measure of initial arm movement direction to quantify whether motor planning occurred in retinal coordinates (not accounting for eye motion) or was spatially correct (incorporating eye velocity). Results showed that the eye velocity was nearly fully taken into account by the neuronal areas involved in the visuomotor velocity transformation (between 75% and 102%). In particular, these neuronal pathways accounted for the nonlinear effects due to the relative velocity between the target and the eye. In conclusion, the brain network transforming visual motion into a motor plan for manual tracking adequately uses extraretinal signals about eye velocity.

Abnormalities in whisking behaviour are associated with lesions in brain stem nuclei in a mouse model of amyotrophic lateral sclerosis.

PubMed

Grant, Robyn A; Sharp, Paul S; Kennerley, Aneurin J; Berwick, Jason; Grierson, Andrew; Ramesh, Tennore; Prescott, Tony J

2014-02-01

The transgenic SOD1(G93A) mouse is a model of human amyotrophic lateral sclerosis (ALS) and recapitulates many of the pathological hallmarks observed in humans, including motor neuron degeneration in the brain and the spinal cord. In mice, neurodegeneration particularly impacts on the facial nuclei in the brainstem. Motor neurons innervating the whisker pad muscles originate in the facial nucleus of the brain stem, with contractions of these muscles giving rise to "whisking" one of the fastest movements performed by mammals. A longitudinal study was conducted on SOD1(G93A) mice and wild-type litter mate controls, comparing: (i) whisker movements using high-speed video recordings and automated whisker tracking, and (ii) facial nucleus degeneration using MRI. Results indicate that while whisking still occurs in SOD1(G93A) mice and is relatively resistant to neurodegeneration, there are significant disruptions to certain whisking behaviours, which correlate with facial nuclei lesions, and may be as a result of specific facial muscle degeneration. We propose that measures of mouse whisker movement could potentially be used in tandem with measures of limb dysfunction as biomarkers of disease onset and progression in ALS mice and offers a novel method for testing the efficacy of novel therapeutic compounds. Copyright © 2013 Elsevier B.V. All rights reserved.

Automatic prediction of tongue muscle activations using a finite element model.

PubMed

Stavness, Ian; Lloyd, John E; Fels, Sidney

2012-11-15

Computational modeling has improved our understanding of how muscle forces are coordinated to generate movement in musculoskeletal systems. Muscular-hydrostat systems, such as the human tongue, involve very different biomechanics than musculoskeletal systems, and modeling efforts to date have been limited by the high computational complexity of representing continuum-mechanics. In this study, we developed a computationally efficient tracking-based algorithm for prediction of muscle activations during dynamic 3D finite element simulations. The formulation uses a local quadratic-programming problem at each simulation time-step to find a set of muscle activations that generated target deformations and movements in finite element muscular-hydrostat models. We applied the technique to a 3D finite element tongue model for protrusive and bending movements. Predicted muscle activations were consistent with experimental recordings of tongue strain and electromyography. Upward tongue bending was achieved by recruitment of the superior longitudinal sheath muscle, which is consistent with muscular-hydrostat theory. Lateral tongue bending, however, required recruitment of contralateral transverse and vertical muscles in addition to the ipsilateral margins of the superior longitudinal muscle, which is a new proposition for tongue muscle coordination. Our simulation framework provides a new computational tool for systematic analysis of muscle forces in continuum-mechanics models that is complementary to experimental data and shows promise for eliciting a deeper understanding of human tongue function. Copyright © 2012 Elsevier Ltd. All rights reserved.

Connectivity planning to address climate change.

PubMed

Nuñez, Tristan A; Lawler, Joshua J; McRae, Brad H; Pierce, D John; Krosby, Meade B; Kavanagh, Darren M; Singleton, Peter H; Tewksbury, Joshua J

2013-04-01

As the climate changes, human land use may impede species from tracking areas with suitable climates. Maintaining connectivity between areas of different temperatures could allow organisms to move along temperature gradients and allow species to continue to occupy the same temperature space as the climate warms. We used a coarse-filter approach to identify broad corridors for movement between areas where human influence is low while simultaneously routing the corridors along present-day spatial gradients of temperature. We modified a cost-distance algorithm to model these corridors and tested the model with data on current land-use and climate patterns in the Pacific Northwest of the United States. The resulting maps identified a network of patches and corridors across which species may move as climates change. The corridors are likely to be robust to uncertainty in the magnitude and direction of future climate change because they are derived from gradients and land-use patterns. The assumptions we applied in our model simplified the stability of temperature gradients and species responses to climate change and land use, but the model is flexible enough to be tailored to specific regions by incorporating other climate variables or movement costs. When used at appropriate resolutions, our approach may be of value to local, regional, and continental conservation initiatives seeking to promote species movements in a changing climate. Planificación de Conectividad para Atender el Cambio Climático. © 2013 Society for Conservation Biology.

An eye tracking study of bloodstain pattern analysts during pattern classification.

PubMed

Arthur, R M; Hoogenboom, J; Green, R D; Taylor, M C; de Bruin, K G

2018-05-01

Bloodstain pattern analysis (BPA) is the forensic discipline concerned with the classification and interpretation of bloodstains and bloodstain patterns at the crime scene. At present, it is unclear exactly which stain or pattern properties and their associated values are most relevant to analysts when classifying a bloodstain pattern. Eye tracking technology has been widely used to investigate human perception and cognition. Its application to forensics, however, is limited. This is the first study to use eye tracking as a tool for gaining access to the mindset of the bloodstain pattern expert. An eye tracking method was used to follow the gaze of 24 bloodstain pattern analysts during an assigned task of classifying a laboratory-generated test bloodstain pattern. With the aid of an automated image-processing methodology, the properties of selected features of the pattern were quantified leading to the delineation of areas of interest (AOIs). Eye tracking data were collected for each AOI and combined with verbal statements made by analysts after the classification task to determine the critical range of values for relevant diagnostic features. Eye-tracking data indicated that there were four main regions of the pattern that analysts were most interested in. Within each region, individual elements or groups of elements that exhibited features associated with directionality, size, colour and shape appeared to capture the most interest of analysts during the classification task. The study showed that the eye movements of trained bloodstain pattern experts and their verbal descriptions of a pattern were well correlated.

Ocular tracking responses to background motion gated by feature-based attention.

PubMed

Souto, David; Kerzel, Dirk

2014-09-01

Involuntary ocular tracking responses to background motion offer a window on the dynamics of motion computations. In contrast to spatial attention, we know little about the role of feature-based attention in determining this ocular response. To probe feature-based effects of background motion on involuntary eye movements, we presented human observers with a balanced background perturbation. Two clouds of dots moved in opposite vertical directions while observers tracked a target moving in horizontal direction. Additionally, they had to discriminate a change in the direction of motion (±10° from vertical) of one of the clouds. A vertical ocular following response occurred in response to the motion of the attended cloud. When motion selection was based on motion direction and color of the dots, the peak velocity of the tracking response was 30% of the tracking response elicited in a single task with only one direction of background motion. In two other experiments, we tested the effect of the perturbation when motion selection was based on color, by having motion direction vary unpredictably, or on motion direction alone. Although the gain of pursuit in the horizontal direction was significantly reduced in all experiments, indicating a trade-off between perceptual and oculomotor tasks, ocular responses to perturbations were only observed when selection was based on both motion direction and color. It appears that selection by motion direction can only be effective for driving ocular tracking when the relevant elements can be segregated before motion onset. Copyright © 2014 the American Physiological Society.

Applying acoustic telemetry to understand contaminant exposure and bioaccumulation patterns in mobile fishes.

PubMed

Taylor, Matthew D; van der Meulen, Dylan E; Brodie, Stephanie; Cadiou, Gwenaël; Knott, Nathan A

2018-06-01

Contamination in urbanised estuaries presents a risk to human health, and to the viability of populations of exploited species. Assessing animal movements in relation to contaminated areas may help to explain patterns in bioaccumulation, and assist in the effective management of health risks associated with consumption of exploited species. Using polychlorinated dibenzodioxin and polychlorinated dibenzofuran (PCDD/Fs) contamination in Sydney Harbour estuary as a case study, we present a study that links movement patterns resolved using acoustic telemetry to the accumulation of contaminants in mobile fish on a multi-species basis. Fifty-four individuals across six exploited species (Sea Mullet Mugil cephalus; Luderick Girella tricuspidata; Yellowfin Bream Acanthopagrus australis; Silver Trevally Pseudocaranx georgianus; Mulloway Argyrosomus japonicus; Yellowtail Kingfish Seriola lalandi) were tagged with acoustic transmitters, and their movements tracked for up to 3years. There was substantial inter-specific variation in fish distribution along the estuary. The proportion of distribution that overlapped with contaminated areas explained 84-98% of the inter-specific variation in lipid-standardised biota PCDD/F concentration. There was some seasonal variation in distribution along the estuary, but movement patterns indicated that Sea Mullet, Yellowfin Bream, Silver Trevally, and Mulloway were likely to be exposed to contaminated areas during the period of gonadal maturation. Acoustic telemetry allows examination of spatial and temporal patterns in exposure to contamination. When used alongside biota sampling and testing, this offers a powerful approach to assess exposure, bioaccumulation, and potential risks faced by different species, as well as human health risks associated with their consumption. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Trajectory Adjustments Underlying Task-Specific Intermittent Force Behaviors and Muscular Rhythms

PubMed Central

Chen, Yi-Ching; Lin, Yen-Ting; Huang, Chien-Ting; Shih, Chia-Li; Yang, Zong-Ru; Hwang, Ing-Shiou

2013-01-01

Force intermittency is one of the major causes of motor variability. Focusing on the dynamics of force intermittency, this study was undertaken to investigate how force trajectory is fine-tuned for static and dynamic force-tracking of a comparable physical load. Twenty-two healthy adults performed two unilateral resistance protocols (static force-tracking at 75% maximal effort and dynamic force-tracking in the range of 50%–100% maximal effort) using the left hand. The electromyographic activity and force profile of the designated hand were monitored. Gripping force was off-line decomposed into a primary movement spectrally identical to the target motion and a force intermittency profile containing numerous force pulses. The results showed that dynamic force-tracking exhibited greater intermittency amplitude and force pulse but a smaller amplitude ratio of primary movement to force intermittency than static force-tracking. Multi-scale entropy analysis revealed that force intermittency during dynamic force-tracking was more complex on a low time scale but more regular on a high time scale than that of static force-tracking. Together with task-dependent force intermittency properties, dynamic force-tracking exhibited a smaller 8–12 Hz muscular oscillation but a more potentiated muscular oscillation at 35–50 Hz than static force-tracking. In conclusion, force intermittency reflects differing trajectory controls for static and dynamic force-tracking. The target goal of dynamic tracking is achieved through trajectory adjustments that are more intricate and more frequent than those of static tracking, pertaining to differing organizations and functioning of muscular oscillations in the alpha and gamma bands. PMID:24098640

Tracking control of time-varying knee exoskeleton disturbed by interaction torque.

PubMed

Li, Zhan; Ma, Wenhao; Yin, Ziguang; Guo, Hongliang

2017-11-01

Knee exoskeletons have been increasingly applied as assistive devices to help lower-extremity impaired people to make their knee joints move through providing external movement compensation. Tracking control of knee exoskeletons guided by human intentions often encounters time-varying (time-dependent) issues and the disturbance interaction torque, which may dramatically put an influence up on their dynamic behaviors. Inertial and viscous parameters of knee exoskeletons can be estimated to be time-varying due to unexpected mechanical vibrations and contact interactions. Moreover, the interaction torque produced from knee joint of wearers has an evident disturbance effect on regular motions of knee exoskeleton. All of these points can increase difficultly of accurate control of knee exoskeletons to follow desired joint angle trajectories. This paper proposes a novel control strategy for controlling knee exoskeleton with time-varying inertial and viscous coefficients disturbed by interaction torque. Such designed controller is able to make the tracking error of joint angle of knee exoskeletons exponentially converge to zero. Meanwhile, the proposed approach is robust to guarantee the tracking error bounded when the interaction torque exists. Illustrative simulation and experiment results are presented to show efficiency of the proposed controller. Additionally, comparisons with gradient dynamic (GD) approach and other methods are also presented to demonstrate efficiency and superiority of the proposed control strategy for tracking joint angle of knee exoskeleton. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

When self-tracking enters physical rehabilitation: From ‘pushed’ self-tracking to ongoing affective encounters in arrangements of care

PubMed Central

Schwennesen, Nete

2017-01-01

In this paper, I explore what happens when self-tracking technologies and devices travel into the context of physical rehabilitation and come to constitute what Lupton has called ‘pushed’ self-tracking. By unpacking the processes through which a self-tracking technology is put to use in physical rehabilitation in Denmark, and the kind of relationships patients and healthcare providers establish with and through this technology, I illustrate how a new geography of responsibility is constituted, where responsibility for professional guidance is delegated to the technology and patients are expected to produce and engage in movement data. In contrast to the image of ‘pushing’ as a single activity where one part (technology) has the authority to push the other (patient) to act in certain ways, I argue that ‘the push’ is better described as an ongoing and contingent process that evolves through affective and affecting encounters between human (patients, healthcare providers) and nonhuman (technology, algorithms, software) actors. I illustrate that even though responsibility is delegated to the technology, it is unable to make bodies move by itself. Rather, what determines what ‘it’ becomes and how ‘it’ comes to act is enabled by the constitution of a wider arrangement of care and the arrangements’ ability to affect and respond to particular bodies.

Sand dune tracking from satellite laser altimetry

NASA Astrophysics Data System (ADS)

Dabboor, Mohammed

Substantial problems arise from sand movement in arid and semi-arid countries. Sand poses a threat to infrastructure, agricultural and urban areas. These issues are caused by the encroachment of sand on roads and railway tracks, farmland, towns and villages, and airports, to name a few. Sand movement highly depends on geomorphology including vegetation cover, shape and height of the terrain, and grain size of the sand. However, wind direction and speed are the most important factors that affect efficient sand movement. The direction of the movement depends on the main direction of the wind, but it has been shown that a minimum wind speed is required, e.g. wind gusts, to initiate sand transport. This fact prevents a simple calculation of sand transport from conventional wind data as wind records rarely contain sub-minute intervals masking out any wind gusts. An alternative of predicting sand transport is the direct observation of sand advance by in situ measurements or via satellite. Until recently, satellite imagery was the only means to compare dune shape and position for predicting dune migration over several years. In 2003, the NASA laser altimetry mission ICESat became operational and monitors elevations over all surface types including sand dunes with an accuracy of about 10-20 cm. In this study, ICESat observations from repeat tracks (tracks overlapping eachother within 50 m) are used to derive sand dune advance and direction. The method employs a correlation of the elevation profiles over several dunes and was sucessfully validated with synthetic data. The accuracy of this method is 5 meters of dune advance. One of the most active areas exhibiting sand and dune movement is the area of the Arabian Peninsula. Approximately one-third of the Arabian Peninsula is covered by sand dunes. Different wind regimes (Shamal, Kaus) cause sand dune movement in the selected study area in the eastern part of the Arabian Peninsula between 20-25 degrees North and 45-55 degrees East. Two different dune types can be distinguised which exhibit a 6 m and 26 m average dune advance over a 6 months time period. Wind speed/direction data and the observed dune advance agree well and indicate that dune tracking from space is a viable alternative to in situ or model data.

Analysis of temporal variation in human masticatory cycles during gum chewing.

PubMed

Crane, Elizabeth A; Rothman, Edward D; Childers, David; Gerstner, Geoffrey E

2013-10-01

The study investigated modulation of fast and slow opening (FO, SO) and closing (FC, SC) chewing cycle phases using gum-chewing sequences in humans. Twenty-two healthy adult subjects participated by chewing gum for at least 20s on the right side and at least 20s on the left side while jaw movements were tracked with a 3D motion analysis system. Jaw movement data were digitized, and chewing cycle phases were identified and analysed for all chewing cycles in a complete sequence. All four chewing cycle phase durations were more variant than total cycle durations, a result found in other non-human primates. Significant negative correlations existed between the opening phases, SO and FO, and between the closing phases, SC and FC; however, there was less consistency in terms of which phases were negatively correlated both between subjects, and between chewing sides within subjects, compared with results reported in other species. The coordination of intra-cycle phases appears to be flexible and to follow complex rules during gum-chewing in humans. Alternatively, the observed intra-cycle phase relationships could simply reflect: (1) variation in jaw kinematics due to variation in how gum was handled by the tongue on a chew-by-chew basis in our experimental design or (2) by variation due to data sampling noise and/or how phases were defined and identified. Copyright © 2013 Elsevier Ltd. All rights reserved.

Extracting motor synergies from random movements for low-dimensional task-space control of musculoskeletal robots.

PubMed

Fu, Kin Chung Denny; Dalla Libera, Fabio; Ishiguro, Hiroshi

2015-10-08

In the field of human motor control, the motor synergy hypothesis explains how humans simplify body control dimensionality by coordinating groups of muscles, called motor synergies, instead of controlling muscles independently. In most applications of motor synergies to low-dimensional control in robotics, motor synergies are extracted from given optimal control signals. In this paper, we address the problems of how to extract motor synergies without optimal data given, and how to apply motor synergies to achieve low-dimensional task-space tracking control of a human-like robotic arm actuated by redundant muscles, without prior knowledge of the robot. We propose to extract motor synergies from a subset of randomly generated reaching-like movement data. The essence is to first approximate the corresponding optimal control signals, using estimations of the robot's forward dynamics, and to extract the motor synergies subsequently. In order to avoid modeling difficulties, a learning-based control approach is adopted such that control is accomplished via estimations of the robot's inverse dynamics. We present a kernel-based regression formulation to estimate the forward and the inverse dynamics, and a sliding controller in order to cope with estimation error. Numerical evaluations show that the proposed method enables extraction of motor synergies for low-dimensional task-space control.

Tracker Toolkit

NASA Technical Reports Server (NTRS)

Lewis, Steven J.; Palacios, David M.

2013-01-01

This software can track multiple moving objects within a video stream simultaneously, use visual features to aid in the tracking, and initiate tracks based on object detection in a subregion. A simple programmatic interface allows plugging into larger image chain modeling suites. It extracts unique visual features for aid in tracking and later analysis, and includes sub-functionality for extracting visual features about an object identified within an image frame. Tracker Toolkit utilizes a feature extraction algorithm to tag each object with metadata features about its size, shape, color, and movement. Its functionality is independent of the scale of objects within a scene. The only assumption made on the tracked objects is that they move. There are no constraints on size within the scene, shape, or type of movement. The Tracker Toolkit is also capable of following an arbitrary number of objects in the same scene, identifying and propagating the track of each object from frame to frame. Target objects may be specified for tracking beforehand, or may be dynamically discovered within a tripwire region. Initialization of the Tracker Toolkit algorithm includes two steps: Initializing the data structures for tracked target objects, including targets preselected for tracking; and initializing the tripwire region. If no tripwire region is desired, this step is skipped. The tripwire region is an area within the frames that is always checked for new objects, and all new objects discovered within the region will be tracked until lost (by leaving the frame, stopping, or blending in to the background).

Real-time eye tracking for the assessment of driver fatigue.

PubMed

Xu, Junli; Min, Jianliang; Hu, Jianfeng

2018-04-01

Eye-tracking is an important approach to collect evidence regarding some participants' driving fatigue. In this contribution, the authors present a non-intrusive system for evaluating driver fatigue by tracking eye movement behaviours. A real-time eye-tracker was used to monitor participants' eye state for collecting eye-movement data. These data are useful to get insights into assessing participants' fatigue state during monotonous driving. Ten healthy subjects performed continuous simulated driving for 1-2 h with eye state monitoring on a driving simulator in this study, and these measured features of the fixation time and the pupil area were recorded via using eye movement tracking device. For achieving a good cost-performance ratio and fast computation time, the fuzzy K -nearest neighbour was employed to evaluate and analyse the influence of different participants on the variations in the fixation duration and pupil area of drivers. The findings of this study indicated that there are significant differences in domain value distribution of the pupil area under the condition with normal and fatigue driving state. Result also suggests that the recognition accuracy by jackknife validation reaches to about 89% in average, implying that show a significant potential of real-time applicability of the proposed approach and is capable of detecting driver fatigue.

Real-time eye tracking for the assessment of driver fatigue

PubMed Central

Xu, Junli; Min, Jianliang

2018-01-01

Eye-tracking is an important approach to collect evidence regarding some participants’ driving fatigue. In this contribution, the authors present a non-intrusive system for evaluating driver fatigue by tracking eye movement behaviours. A real-time eye-tracker was used to monitor participants’ eye state for collecting eye-movement data. These data are useful to get insights into assessing participants’ fatigue state during monotonous driving. Ten healthy subjects performed continuous simulated driving for 1–2 h with eye state monitoring on a driving simulator in this study, and these measured features of the fixation time and the pupil area were recorded via using eye movement tracking device. For achieving a good cost-performance ratio and fast computation time, the fuzzy K-nearest neighbour was employed to evaluate and analyse the influence of different participants on the variations in the fixation duration and pupil area of drivers. The findings of this study indicated that there are significant differences in domain value distribution of the pupil area under the condition with normal and fatigue driving state. Result also suggests that the recognition accuracy by jackknife validation reaches to about 89% in average, implying that show a significant potential of real-time applicability of the proposed approach and is capable of detecting driver fatigue. PMID:29750113

Tracking hand movements captures the response dynamics of the evaluative priming effect.

PubMed

Kawakami, Naoaki; Miura, Emi

2018-06-08

We tested the response dynamics of the evaluative priming effect (i.e. facilitation of target responses following evaluatively congruent compared with evaluatively incongruent primes) using a mouse tracking procedure that records hand movements during the execution of categorisation tasks. In Experiment 1, when participants performed the evaluative categorisation task but not the non-evaluative semantic categorisation task, their mouse trajectories for evaluatively incongruent trials curved more toward the opposite response than those for evaluatively congruent trials, indicating the emergence of evaluative priming effects based on response competition. In Experiment 2, implementing a task-switching procedure in which evaluative and non-evaluative categorisation tasks were intermixed, we obtained reliable evaluative priming effects in the non-evaluative semantic categorisation task as well as in the evaluative categorisation task when participants assigned attention to the evaluative stimulus dimension. Analyses of hand movements revealed that the evaluative priming effects in the evaluative categorisation task were reflected in the mouse trajectories, while evaluative priming effects in the non-evaluative categorisation tasks were reflected in initiation times (i.e. the time elapsed between target onset and first mouse movement). Based on these findings, we discuss the methodological benefits of the mouse tracking procedure and the underlying processes of evaluative priming effects.

The reliability and validity of subjective notational analysis in comparison to global positioning system tracking to assess athlete movement patterns.

PubMed

Doğramac, Sera N; Watsford, Mark L; Murphy, Aron J

2011-03-01

Subjective notational analysis can be used to track players and analyse movement patterns during match-play of team sports such as futsal. The purpose of this study was to establish the validity and reliability of the Event Recorder for subjective notational analysis. A course was designed, replicating ten minutes of futsal match-play movement patterns, where ten participants undertook the course. The course allowed a comparison of data derived from subjective notational analysis, to the known distances of the course, and to GPS data. The study analysed six locomotor activity categories, focusing on total distance covered, total duration of activities and total frequency of activities. The values between the known measurements and the Event Recorder were similar, whereas the majority of significant differences were found between the Event Recorder and GPS values. The reliability of subjective notational analysis was established with all ten participants being analysed on two occasions, as well as analysing five random futsal players twice during match-play. Subjective notational analysis is a valid and reliable method of tracking player movements, and may be a preferred and more effective method than GPS, particularly for indoor sports such as futsal, and field sports where short distances and changes in direction are observed.

From forager tracks to prey distributions: an application to tuna vessel monitoring systems (VMS).

PubMed

Walker, Emily; Rivoirard, Jacques; Gaspar, Philippe; Bez, Nicolas

2015-04-01

In the open ocean, movements of migratory fish populations are typically surveyed using tagging methods that are subject to low sample sizes for archive tags, except for a few notable examples, and poor temporal resolution for conventional tags. Alternatively, one can infer patterns of movement of migratory fish by tracking movements of their predators, i.e., fishing vessels, whose navigational systems (e.g., GPS) provide accurate and frequent VMS (vessel monitoring system) records of movement in pursuit of prey. In this paper, we develop a state-space model that infers the foraging activities of fishing vessels from their tracks. Second, we link foraging activities to probabilities of tuna presence. Finally, using multivariate geostatistical interpolation (cokriging) we map the probability of tuna presence together with their estimation variances and produce a time series of indices of abundance. While the segmentation of the trajectories is validated by observers' data, the present VMS-index is compared to catch rate and proved to be useful for management perspectives. The approach reported in this manuscript extends beyond the case study considered. It can be applied to any foragers that engage in an attempt of capture when they see prey and for whom this attempt is linked to a tractable change in behavior.

Airborne sensors for detecting large marine debris at sea.

PubMed

Veenstra, Timothy S; Churnside, James H

2012-01-01

The human eye is an excellent, general-purpose airborne sensor for detecting marine debris larger than 10 cm on or near the surface of the water. Coupled with the human brain, it can adjust for light conditions and sea-surface roughness, track persistence, differentiate color and texture, detect change in movement, and combine all of the available information to detect and identify marine debris. Matching this performance with computers and sensors is difficult at best. However, there are distinct advantages over the human eye and brain that sensors and computers can offer such as the ability to use finer spectral resolution, to work outside the spectral range of human vision, to control the illumination, to process the information in ways unavailable to the human vision system, to provide a more objective and reproducible result, to operate from unmanned aircraft, and to provide a permanent record that can be used for later analysis. Copyright © 2010 Elsevier Ltd. All rights reserved.

Wearable Tracking Tags Test Privacy Boundaries at the U. of Washington

ERIC Educational Resources Information Center

Dotinga, Randy

2008-01-01

Tags such as the radio-frequency identifications or RFIDs are devices that make it possible for individuals to be tracked and their location reported back to a database. The devices--chips with radio antennas--emit signals, and tracking them reveals the movement of people or things. Many stores use the technology to catch shoplifters at exits. To…

TrackPlot Enhancements: Support for Multiple Animal Tracks and Gyros

DTIC Science & Technology

2015-09-30

visualization and kinematic analysis of marine animal movements derived from archival tag data. Tags are supported that have sensors for pressure, acceleration...1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. TrackPlot Enhancements: Support for Multiple Animal ...in combination with accelerometer and magnetometer data. 2) the extraction and frequency analysis of accelerations and rotation in animal

CEFR and Eye Movement Characteristics during EFL Reading: The Case of Intermediate Readers

ERIC Educational Resources Information Center

Dolgunsöz, Emrah; Sariçoban, Arif

2016-01-01

This study primarily aims to (1) examine the relationship between foreign language reading proficiency and eye movements during reading, and (2) to describe eye movement differences between two CEFR proficiency groups (B1 and B2) by using eye tracking technique. 57 learners of EFL were tested under two experimental conditions: Natural L2 reading…

Comparison of global positioning and computer-based tracking systems for measuring player movement distance during Australian football.

PubMed

Edgecomb, S J; Norton, K I

2006-05-01

Sports scientists require a thorough understanding of the energy demands of sports and physical activities so that optimal training strategies and game simulations can be constructed. A range of techniques has been used to both directly assess and estimate the physiological and biochemical changes during competition. A fundamental approach to understanding the contribution of the energy systems in physical activity has involved the use of time-motion studies. A number of tools have been used from simple pen and paper methods, the use of video recordings, to sophisticated electronic tracking devices. Depending on the sport, there may be difficulties in using electronic tracking devices because of concerns of player safety. This paper assesses two methods currently used to measure player movement patterns during competition: (1) global positioning technology (GPS) and (2) a computer-based tracking (CBT) system that relies on a calibrated miniaturised playing field and mechanical movements of the tracker. A range of ways was used to determine the validity and reliability of these methods for tracking Australian footballers for distance covered during games. Comparisons were also made between these methods. The results indicate distances measured using CBT overestimated the actual values (measured with a calibrated trundle wheel) by an average of about 5.8%. The GPS system overestimated the actual values by about 4.8%. Distances measured using CBT in experienced hands were as accurate as the GPS technology. Both systems showed relatively small errors in true distances.

10-Month-Old Infants Are Sensitive to the Time Course of Perceived Actions: Eye-Tracking and EEG Evidence.

PubMed

Bache, Cathleen; Springer, Anne; Noack, Hannes; Stadler, Waltraud; Kopp, Franziska; Lindenberger, Ulman; Werkle-Bergner, Markus

2017-01-01

Research has shown that infants are able to track a moving target efficiently - even if it is transiently occluded from sight. This basic ability allows prediction of when and where events happen in everyday life. Yet, it is unclear whether, and how, infants internally represent the time course of ongoing movements to derive predictions. In this study, 10-month-old crawlers observed the video of a same-aged crawling baby that was transiently occluded and reappeared in either a temporally continuous or non-continuous manner (i.e., delayed by 500 ms vs. forwarded by 500 ms relative to the real-time movement). Eye movement and rhythmic neural brain activity (EEG) were measured simultaneously. Eye movement analyses showed that infants were sensitive to slight temporal shifts in movement continuation after occlusion. Furthermore, brain activity associated with sensorimotor processing differed between observation of continuous and non-continuous movements. Early sensitivity to an action's timing may hence be explained within the internal real-time simulation account of action observation. Overall, the results support the hypothesis that 10-month-old infants are well prepared for internal representation of the time course of observed movements that are within the infants' current motor repertoire.

10-Month-Old Infants Are Sensitive to the Time Course of Perceived Actions: Eye-Tracking and EEG Evidence

PubMed Central

Bache, Cathleen; Springer, Anne; Noack, Hannes; Stadler, Waltraud; Kopp, Franziska; Lindenberger, Ulman; Werkle-Bergner, Markus

2017-01-01

Research has shown that infants are able to track a moving target efficiently – even if it is transiently occluded from sight. This basic ability allows prediction of when and where events happen in everyday life. Yet, it is unclear whether, and how, infants internally represent the time course of ongoing movements to derive predictions. In this study, 10-month-old crawlers observed the video of a same-aged crawling baby that was transiently occluded and reappeared in either a temporally continuous or non-continuous manner (i.e., delayed by 500 ms vs. forwarded by 500 ms relative to the real-time movement). Eye movement and rhythmic neural brain activity (EEG) were measured simultaneously. Eye movement analyses showed that infants were sensitive to slight temporal shifts in movement continuation after occlusion. Furthermore, brain activity associated with sensorimotor processing differed between observation of continuous and non-continuous movements. Early sensitivity to an action’s timing may hence be explained within the internal real-time simulation account of action observation. Overall, the results support the hypothesis that 10-month-old infants are well prepared for internal representation of the time course of observed movements that are within the infants’ current motor repertoire. PMID:28769831

Kinect based real-time position calibration for nasal endoscopic surgical navigation system

NASA Astrophysics Data System (ADS)

Fan, Jingfan; Yang, Jian; Chu, Yakui; Ma, Shaodong; Wang, Yongtian

2016-03-01

Unanticipated, reactive motion of the patient during skull based tumor resective surgery is the source of the consequence that the nasal endoscopic tracking system is compelled to be recalibrated. To accommodate the calibration process with patient's movement, this paper developed a Kinect based Real-time positional calibration method for nasal endoscopic surgical navigation system. In this method, a Kinect scanner was employed as the acquisition part of the point cloud volumetric reconstruction of the patient's head during surgery. Then, a convex hull based registration algorithm aligned the real-time image of the patient head with a model built upon the CT scans performed in the preoperative preparation to dynamically calibrate the tracking system if a movement was detected. Experimental results confirmed the robustness of the proposed method, presenting a total tracking error within 1 mm under the circumstance of relatively violent motions. These results point out the tracking accuracy can be retained stably and the potential to expedite the calibration of the tracking system against strong interfering conditions, demonstrating high suitability for a wide range of surgical applications.

History of Illicit Stimulant Use Is Not Associated with Long-Lasting Changes in Learning of Fine Motor Skills in Humans

PubMed Central

Todd, Gabrielle; Pearson-Dennett, Verity; Flavel, Stanley C.; Haberfield, Miranda; Edwards, Hannah; White, Jason M.

2016-01-01

Little is known about the long-lasting effect of use of illicit stimulant drugs on learning of new motor skills. We hypothesised that abstinent individuals with a history of primarily methamphetamine and ecstasy use would exhibit normal learning of a visuomotor tracking task compared to controls. The study involved three groups: abstinent stimulant users (n = 21; 27 ± 6 yrs) and two gender-matched control groups comprising nondrug users (n = 16; 22 ± 4 yrs) and cannabis users (n = 16; 23 ± 5 yrs). Motor learning was assessed with a three-minute visuomotor tracking task. Subjects were instructed to follow a moving target on a computer screen with movement of the index finger. Metacarpophalangeal joint angle and first dorsal interosseous electromyographic activity were recorded. Pattern matching was assessed by cross-correlation of the joint angle and target traces. Distance from the target (tracking error) was also calculated. Motor learning was evident in the visuomotor task. Pattern matching improved over time (cross-correlation coefficient) and tracking error decreased. However, task performance did not differ between the groups. The results suggest that learning of a new fine visuomotor skill is unchanged in individuals with a history of illicit stimulant use. PMID:26819778

History of Illicit Stimulant Use Is Not Associated with Long-Lasting Changes in Learning of Fine Motor Skills in Humans.

PubMed

Todd, Gabrielle; Pearson-Dennett, Verity; Flavel, Stanley C; Haberfield, Miranda; Edwards, Hannah; White, Jason M

2016-01-01

Little is known about the long-lasting effect of use of illicit stimulant drugs on learning of new motor skills. We hypothesised that abstinent individuals with a history of primarily methamphetamine and ecstasy use would exhibit normal learning of a visuomotor tracking task compared to controls. The study involved three groups: abstinent stimulant users (n = 21; 27 ± 6 yrs) and two gender-matched control groups comprising nondrug users (n = 16; 22 ± 4 yrs) and cannabis users (n = 16; 23 ± 5 yrs). Motor learning was assessed with a three-minute visuomotor tracking task. Subjects were instructed to follow a moving target on a computer screen with movement of the index finger. Metacarpophalangeal joint angle and first dorsal interosseous electromyographic activity were recorded. Pattern matching was assessed by cross-correlation of the joint angle and target traces. Distance from the target (tracking error) was also calculated. Motor learning was evident in the visuomotor task. Pattern matching improved over time (cross-correlation coefficient) and tracking error decreased. However, task performance did not differ between the groups. The results suggest that learning of a new fine visuomotor skill is unchanged in individuals with a history of illicit stimulant use.

Anatomical Calibration through Post-Processing of Standard Motion Tests Data.

PubMed

Kong, Weisheng; Sessa, Salvatore; Zecca, Massimiliano; Takanishi, Atsuo

2016-11-28

The inertial measurement unit is popularly used as a wearable and flexible tool for human motion tracking. Sensor-to-body alignment, or anatomical calibration (AC), is fundamental to improve accuracy and reliability. Current AC methods either require extra movements or are limited to specific joints. In this research, the authors propose a novel method to achieve AC from standard motion tests (such as walking, or sit-to-stand), and compare the results with the AC obtained from specially designed movements. The proposed method uses the limited acceleration range on medial-lateral direction, and applies principal component analysis to estimate the sagittal plane, while the vertical direction is estimated from acceleration during quiet stance. The results show a good correlation between the two sets of IMUs placed on frontal/back and lateral sides of head, trunk and lower limbs. Moreover, repeatability and convergence were verified. The AC obtained from sit-to-stand and walking achieved similar results as the movements specifically designed for upper and lower body AC, respectively, except for the feet. Therefore, the experiments without AC performed can be recovered through post-processing on the walking and sit-to-stand data. Moreover, extra movements for AC can be avoided during the experiment and instead achieved through the proposed method.

49 CFR 236.203 - Hand operated crossover between main tracks; protection.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) Electric locking of the switches of the crossover. Signals governing movements over either switch shall... crossover is occupied by a train, locomotive or car in such a manner as to foul the main track. It shall not... electric locking releases. ...

49 CFR 236.203 - Hand operated crossover between main tracks; protection.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) Electric locking of the switches of the crossover. Signals governing movements over either switch shall... crossover is occupied by a train, locomotive or car in such a manner as to foul the main track. It shall not... electric locking releases. ...

49 CFR 236.203 - Hand operated crossover between main tracks; protection.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) Electric locking of the switches of the crossover. Signals governing movements over either switch shall... crossover is occupied by a train, locomotive or car in such a manner as to foul the main track. It shall not... electric locking releases. ...

49 CFR 236.203 - Hand operated crossover between main tracks; protection.

Code of Federal Regulations, 2011 CFR

2011-10-01

...) Electric locking of the switches of the crossover. Signals governing movements over either switch shall... crossover is occupied by a train, locomotive or car in such a manner as to foul the main track. It shall not... electric locking releases. ...

49 CFR 236.203 - Hand operated crossover between main tracks; protection.

Code of Federal Regulations, 2010 CFR

2010-10-01

...) Electric locking of the switches of the crossover. Signals governing movements over either switch shall... crossover is occupied by a train, locomotive or car in such a manner as to foul the main track. It shall not... electric locking releases. ...

Time-location analysis for exposure assessment studies of children using a novel global positioning system instrument.

PubMed Central

Elgethun, Kai; Fenske, Richard A; Yost, Michael G; Palcisko, Gary J

2003-01-01

Global positioning system (GPS) technology is used widely for business and leisure activities and offers promise for human time-location studies to evaluate potential exposure to environmental contaminants. In this article we describe the development of a novel GPS instrument suitable for tracking the movements of young children. Eleven children in the Seattle area (2-8 years old) wore custom-designed data-logging GPS units integrated into clothing. Location data were transferred into geographic information systems software for map overlay, visualization, and tabular analysis. Data were grouped into five location categories (in vehicle, inside house, inside school, inside business, and outside) to determine time spent and percentage reception in each location. Additional experiments focused on spatial resolution, reception efficiency in typical environments, and sources of signal interference. Significant signal interference occurred only inside concrete/steel-frame buildings and inside a power substation. The GPS instruments provided adequate spatial resolution (typically about 2-3 m outdoors and 4-5 m indoors) to locate subjects within distinct microenvironments and distinguish a variety of human activities. Reception experiments showed that location could be tracked outside, proximal to buildings, and inside some buildings. Specific location information could identify movement in a single room inside a home, on a playground, or along a fence line. The instrument, worn in a vest or in bib overalls, was accepted by children and parents. Durability of the wiring was improved early in the study to correct breakage problems. The use of GPS technology offers a new level of accuracy for direct quantification of time-location activity patterns in exposure assessment studies. PMID:12515689

Robotic lower limb prosthesis design through simultaneous computer optimizations of human and prosthesis costs

NASA Astrophysics Data System (ADS)

Handford, Matthew L.; Srinivasan, Manoj

2016-02-01

Robotic lower limb prostheses can improve the quality of life for amputees. Development of such devices, currently dominated by long prototyping periods, could be sped up by predictive simulations. In contrast to some amputee simulations which track experimentally determined non-amputee walking kinematics, here, we explicitly model the human-prosthesis interaction to produce a prediction of the user’s walking kinematics. We obtain simulations of an amputee using an ankle-foot prosthesis by simultaneously optimizing human movements and prosthesis actuation, minimizing a weighted sum of human metabolic and prosthesis costs. The resulting Pareto optimal solutions predict that increasing prosthesis energy cost, decreasing prosthesis mass, and allowing asymmetric gaits all decrease human metabolic rate for a given speed and alter human kinematics. The metabolic rates increase monotonically with speed. Remarkably, by performing an analogous optimization for a non-amputee human, we predict that an amputee walking with an appropriately optimized robotic prosthesis can have a lower metabolic cost - even lower than assuming that the non-amputee’s ankle torques are cost-free.

Movement and habitat use of Chinook salmon smolts, northern pikeminnow, and smallmouth bass near the SR 520 bridge, 2007 acoustic tracking study, annual report.

DOT National Transportation Integrated Search

2008-10-01

We used a fine-scale acoustic tracking system to track tagged fish in a 17.2 ha area along a 560 m stretch of the SR : 520 bridge from late May through early August 2007. The study site was the west end of the bridge in Lake : Washington, Washington ...

JPL-20180522-GRACFOf-0001-Twin Spacecraft Launch to Track Earth's Water Movement

NASA Image and Video Library

2018-05-22

A U.S./German space mission to track the continuous movement of water and other changes in Earth's mass on and beneath the planet's surface successfully launched at 12:47 p.m. PDT, May 22, 2018, from the California coast. The twin spacecraft of the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO), a joint NASA/German Research Centre for Geosciences (GFZ) mission, lifted off on a SpaceX Falcon 9 rocket from Space Launch Complex-4E at Vandenberg Air Force Base in California, sharing their ride into space with five Iridium NEXT communications satellites.

Oculomotor Behavior Metrics Change According to Circadian Phase and Time Awake

NASA Technical Reports Server (NTRS)

Flynn-Evans, Erin E.; Tyson, Terence L.; Cravalho, Patrick; Feick, Nathan; Stone, Leland S.

2017-01-01

There is a need for non-invasive, objective measures to forecast performance impairment arising from sleep loss and circadian misalignment, particularly in safety-sensitive occupations. Eye-tracking devices have been used in some operational scenarios, but such devices typically focus on eyelid closures and slow rolling eye movements and are susceptible to the intrusion of head movement artifacts. We hypothesized that an expanded suite of oculomotor behavior metrics, collected during a visual tracking task, would change according to circadian phase and time awake, and could be used as a marker of performance impairment.

Respiration-induced movement correlation for synchronous noninvasive renal cancer surgery.

PubMed

Abhilash, Rakkunedeth H; Chauhan, Sunita

2012-07-01

Noninvasive surgery (NIS), such as high-intensity focused ultrasound (HIFU)-based ablation or radiosurgery, is used for treating tumors and cancers in various parts of the body. The soft tissue targets (usually organs) deform and move as a result of physiological processes such as respiration. Moreover, other deformations induced during surgery by changes in patient position, changes in physical properties caused by repeated exposures and uncertainties resulting from cavitation also occur. In this paper, we present a correlation-based movement prediction technique to address respiration-induced movement of the urological organs while targeting through extracorporeal trans-abdominal route access. Among other organs, kidneys are worst affected during respiratory cycles, with significant three-dimensional displacements observed on the order of 20 mm. Remote access to renal targets such as renal carcinomas and cysts during noninvasive surgery, therefore, requires a tightly controlled real-time motion tracking and quantitative estimate for compensation routine to synchronize the energy source(s) for precise energy delivery to the intended regions. The correlation model finds a mapping between the movement patterns of external skin markers placed on the abdominal access window and the internal movement of the targeted kidney. The coarse estimate of position is then fine-tuned using the Adaptive Neuro-Fuzzy Inference System (ANFIS), thereby achieving a nonlinear mapping. The technical issues involved in this tracking scheme are threefold: the model must have sufficient accuracy in mapping the movement pattern; there must be an image-based tracking scheme to provide the organ position within allowable system latency; and the processing delay resulting from modeling and tracking must be within the achievable prediction horizon to accommodate the latency in the therapeutic delivery system. The concept was tested on ultrasound image sequences collected from 20 healthy volunteers. The results indicate that the modeling technique can be practically integrated into an image-guided noninvasive robotic surgical system with an indicative targeting accuracy of more than 94%. A comparative analysis showed the superiority of this technique over conventional linear mapping and modelfree blind search techniques.

3-D model-based vehicle tracking.

PubMed

Lou, Jianguang; Tan, Tieniu; Hu, Weiming; Yang, Hao; Maybank, Steven J

2005-10-01

This paper aims at tracking vehicles from monocular intensity image sequences and presents an efficient and robust approach to three-dimensional (3-D) model-based vehicle tracking. Under the weak perspective assumption and the ground-plane constraint, the movements of model projection in the two-dimensional image plane can be decomposed into two motions: translation and rotation. They are the results of the corresponding movements of 3-D translation on the ground plane (GP) and rotation around the normal of the GP, which can be determined separately. A new metric based on point-to-line segment distance is proposed to evaluate the similarity between an image region and an instantiation of a 3-D vehicle model under a given pose. Based on this, we provide an efficient pose refinement method to refine the vehicle's pose parameters. An improved EKF is also proposed to track and to predict vehicle motion with a precise kinematics model. Experimental results with both indoor and outdoor data show that the algorithm obtains desirable performance even under severe occlusion and clutter.

Video tracking analysis of behavioral patterns during estrus in goats

PubMed Central

ENDO, Natsumi; RAHAYU, Larasati Puji; ARAKAWA, Toshiya; TANAKA, Tomomi

2015-01-01

Here, we report a new method for measuring behavioral patterns during estrus in goats based on video tracking analysis. Data were collected from cycling goats, which were in estrus (n = 8) or not in estrus (n = 8). An observation pen (2.5 m × 2.5 m) was set up in the corner of the female paddock with one side adjacent to a male paddock. The positions and movements of goats were tracked every 0.5 sec for 10 min by using a video tracking software, and the trajectory data were used for the analysis. There were no significant differences in the durations of standing and walking or the total length of movement. However, the number of approaches to a male and the duration of staying near the male were higher in goats in estrus than in goats not in estrus. The proposed evaluation method may be suitable for detailed monitoring of behavioral changes during estrus in goats. PMID:26560676

Ocean Heat Content Reveals Secrets of Fish Migrations

PubMed Central

Luo, Jiangang; Ault, Jerald S.; Shay, Lynn K.; Hoolihan, John P.; Prince, Eric D.; Brown, Craig A.; Rooker, Jay R.

2015-01-01

For centuries, the mechanisms surrounding spatially complex animal migrations have intrigued scientists and the public. We present a new methodology using ocean heat content (OHC), a habitat metric that is normally a fundamental part of hurricane intensity forecasting, to estimate movements and migration of satellite-tagged marine fishes. Previous satellite-tagging research of fishes using archival depth, temperature and light data for geolocations have been too coarse to resolve detailed ocean habitat utilization. We combined tag data with OHC estimated from ocean circulation and transport models in an optimization framework that substantially improved geolocation accuracy over SST-based tracks. The OHC-based movement track provided the first quantitative evidence that many of the tagged highly migratory fishes displayed affinities for ocean fronts and eddies. The OHC method provides a new quantitative tool for studying dynamic use of ocean habitats, migration processes and responses to environmental changes by fishes, and further, improves ocean animal tracking and extends satellite-based animal tracking data for other potential physical, ecological, and fisheries applications. PMID:26484541

Tracking Three-Dimensional Fish Behavior with a New Marine Acoustic Telemetry System

NASA Technical Reports Server (NTRS)

Brosnan, Ian G.; McGarry, Louise P.; Greene, Charles H.; Steig, Tracey W.; Johnston, Samuel V.; Ehrenberg, John E.

2015-01-01

The persistent monitoring capability provided by acoustic telemetry systems allows us to study behavior, movement, and resource selection of mobile marine animals. Current marine acoustic telemetry systems are challenged by localization errors and limits in the number of animals that can be tracked simultaneously. We designed a new system to provide detection ranges of up to 1 km, to reduce localization errors to less than 1 m, and to increase to 500 the number of unique tags simultaneously tracked. The design builds on HTIs experience of more than a decade developing acoustic telemetry systems for freshwater environments. A field trial of the prototype system was conducted at the University of Washingtons Friday Harbor Marine Laboratory (Friday Harbor, WA). Copper rockfish (Sebastes caurinus) were selected for field trials of this new system because their high site-fidelity and small home ranges provide ample opportunity to track individual fish behavior while testing our ability to characterize the movements of a species of interest to management authorities.

Eye Tracking Dysfunction in Schizophrenia: Characterization and Pathophysiology

PubMed Central

Sereno, Anne B.; Gooding, Diane C.; O’Driscoll, Gilllian A.

2011-01-01

Eye tracking dysfunction (ETD) is one of the most widely replicated behavioral deficits in schizophrenia and is over-represented in clinically unaffected first-degree relatives of schizophrenia patients. Here, we provide an overview of research relevant to the characterization and pathophysiology of this impairment. Deficits are most robust in the maintenance phase of pursuit, particularly during the tracking of predictable target movement. Impairments are also found in pursuit initiation and correlate with performance on tests of motion processing, implicating early sensory processing of motion signals. Taken together, the evidence suggests that ETD involves higher-order structures, including the frontal eye fields, which adjust the gain of the pursuit response to visual and anticipated target movement, as well as early parts of the pursuit pathway, including motion areas (the middle temporal area and the adjacent medial superior temporal area). Broader application of localizing behavioral paradigms in patient and family studies would be advantageous for refining the eye tracking phenotype for genetic studies. PMID:21312405

Tracking Organs Composed of One or Multiple Regions Using Geodesic Active Region Models

NASA Astrophysics Data System (ADS)

Martínez, A.; Jiménez, J. J.

In radiotherapy treatment it is very important to find out the target organs on the medical image sequence in order to determine and apply the proper dose. The techniques to achieve this goal can be classified into extrinsic and intrinsic. Intrinsic techniques only use image processing with medical images associated to the radiotherapy treatment, as we deal in this chapter. To accurately perform this organ tracking it is necessary to find out segmentation and tracking models that were able to be applied to several image modalities involved on a radiotherapy session (CT See Modality , MRI , etc.). The movements of the organs are mainly affected by two factors: breathing and involuntary movements associated with the internal organs or patient positioning. Among the several alternatives to track the organs of interest, a model based on geodesic active regions is proposed. This model has been tested over CT images from the pelvic, cardiac, and thoracic area. A new model for the segmentation of organs composed by more than one region is proposed.

Adaptive optics optical coherence tomography with dynamic retinal tracking

PubMed Central

Kocaoglu, Omer P.; Ferguson, R. Daniel; Jonnal, Ravi S.; Liu, Zhuolin; Wang, Qiang; Hammer, Daniel X.; Miller, Donald T.

2014-01-01

Adaptive optics optical coherence tomography (AO-OCT) is a highly sensitive and noninvasive method for three dimensional imaging of the microscopic retina. Like all in vivo retinal imaging techniques, however, it suffers the effects of involuntary eye movements that occur even under normal fixation. In this study we investigated dynamic retinal tracking to measure and correct eye motion at KHz rates for AO-OCT imaging. A customized retina tracking module was integrated into the sample arm of the 2nd-generation Indiana AO-OCT system and images were acquired on three subjects. Analyses were developed based on temporal amplitude and spatial power spectra in conjunction with strip-wise registration to independently measure AO-OCT tracking performance. After optimization of the tracker parameters, the system was found to correct eye movements up to 100 Hz and reduce residual motion to 10 µm root mean square. Between session precision was 33 µm. Performance was limited by tracker-generated noise at high temporal frequencies. PMID:25071963

Following the movement of Earth’s water on This Week @NASA – May 25, 2018

NASA Image and Video Library

2018-05-25

Tracking the movement of Earth’s water, resupplying the International Space Station, and our Administrator testifies about the agency’s proposed budget – a few of the stories to tell you about – This Week at NASA!

Evaluation of distribution and trans-highway movement of desert bighorn sheep : Arizona Highway 68, final report 588.

DOT National Transportation Integrated Search

2008-08-01

The authors monitored desert bighorn sheep via satellite telemetry, remote cameras, and track beds between 2006 and 2007 to evaluate the effectiveness of the three design features (underpasses) incorporated to facilitate wildlife movement under State...

High-Accuracy Measurement of Small Movement of an Object behind Cloth Using Airborne Ultrasound

NASA Astrophysics Data System (ADS)

Hoshiba, Kotaro; Hirata, Shinnosuke; Hachiya, Hiroyuki

2013-07-01

The acoustic measurement of vital information such as breathing and heartbeat in the standing position whilst the subject is wearing clothes is a difficult problem. In this paper, we present the basic experimental results to measure small movement of an object behind cloth. We measured acoustic characteristics of various types of cloth to obtain the transmission loss through cloth. To observe the relationship between measurement error and target speed under a low signal-to-noise ratio (SNR), we tried to measure the movement of an object behind cloth. The target was placed apart from the cloth to separate the target reflection from the cloth reflection. We found that a small movement of less than 6 mm/s could be observed using the M-sequence, moving target indicator (MTI) filter, and tracking phase difference, when the SNR was less than 0 dB. We also present the results of theoretical error analysis in the MTI filter and phase tracking for high-accuracy measurement. Characteristics of the systematic error were clarified.

Active and reactive behaviour in human mobility: the influence of attraction points on pedestrians

NASA Astrophysics Data System (ADS)

Gutiérrez-Roig, M.; Sagarra, O.; Oltra, A.; Palmer, J. R. B.; Bartumeus, F.; Díaz-Guilera, A.; Perelló, J.

2016-07-01

Human mobility is becoming an accessible field of study, thanks to the progress and availability of tracking technologies as a common feature of smart phones. We describe an example of a scalable experiment exploiting these circumstances at a public, outdoor fair in Barcelona (Spain). Participants were tracked while wandering through an open space with activity stands attracting their attention. We develop a general modelling framework based on Langevin dynamics, which allows us to test the influence of two distinct types of ingredients on mobility: reactive or context-dependent factors, modelled by means of a force field generated by attraction points in a given spatial configuration and active or inherent factors, modelled from intrinsic movement patterns of the subjects. The additive and constructive framework model accounts for some observed features. Starting with the simplest model (purely random walkers) as a reference, we progressively introduce different ingredients such as persistence, memory and perceptual landscape, aiming to untangle active and reactive contributions and quantify their respective relevance. The proposed approach may help in anticipating the spatial distribution of citizens in alternative scenarios and in improving the design of public events based on a facts-based approach.

Active and reactive behaviour in human mobility: the influence of attraction points on pedestrians

PubMed Central

Sagarra, O.; Oltra, A.; Palmer, J. R. B.; Bartumeus, F.; Díaz-Guilera, A.; Perelló, J.

2016-01-01

Human mobility is becoming an accessible field of study, thanks to the progress and availability of tracking technologies as a common feature of smart phones. We describe an example of a scalable experiment exploiting these circumstances at a public, outdoor fair in Barcelona (Spain). Participants were tracked while wandering through an open space with activity stands attracting their attention. We develop a general modelling framework based on Langevin dynamics, which allows us to test the influence of two distinct types of ingredients on mobility: reactive or context-dependent factors, modelled by means of a force field generated by attraction points in a given spatial configuration and active or inherent factors, modelled from intrinsic movement patterns of the subjects. The additive and constructive framework model accounts for some observed features. Starting with the simplest model (purely random walkers) as a reference, we progressively introduce different ingredients such as persistence, memory and perceptual landscape, aiming to untangle active and reactive contributions and quantify their respective relevance. The proposed approach may help in anticipating the spatial distribution of citizens in alternative scenarios and in improving the design of public events based on a facts-based approach. PMID:27493774

Accessible laparoscopic instrument tracking ("InsTrac"): construct validity in a take-home box simulator.

PubMed

Partridge, Roland W; Hughes, Mark A; Brennan, Paul M; Hennessey, Iain A M

2014-08-01

Objective performance feedback has potential to maximize the training benefit of laparoscopic simulators. Instrument movement metrics are, however, currently the preserve of complex and expensive systems. We aimed to develop and validate affordable, user-ready software that provides objective feedback by tracking instrument movement in a "take-home" laparoscopic simulator. Computer-vision processing tracks the movement of colored bands placed around the distal instrument shafts. The position of each instrument is logged from the simulator camera feed and movement metrics calculated in real time. Ten novices (junior doctors) and 13 general surgery trainees (StR) (training years 3-7) performed a standardized task (threading string through hoops) on the eoSim (eoSurgical™ Ltd., Edinburgh, Scotland, United Kingdom) take-home laparoscopic simulator. Statistical analysis was performed using unpaired t tests with Welch's correction. The software was able to track the instrument tips reliably and effectively. Significant differences between the two groups were observed in time to complete task (StR versus novice, 2 minutes 33 seconds versus 9 minutes 53 seconds; P=.01), total distance traveled by instruments (3.29 m versus 11.38 m, respectively; P=.01), average instrument motion smoothness (0.15 mm/second(3) versus 0.06 mm/second(3), respectively; P<.01), and handedness (mean difference between dominant and nondominant hand) (0.55 m versus 2.43 m, respectively; P=.03). There was no significant difference seen in the distance between instrument tips, acceleration, speed of instruments, or time off-screen. We have developed software that brings objective performance feedback to the portable laparoscopic box simulator. Construct validity has been demonstrated. Removing the need for additional motion-tracking hardware makes it affordable and accessible. It is user-ready and has the potential to enhance the training benefit of portable simulators both in the workplace and at home.

Temporal and spatial patterns of habitat use by juveniles of a small coastal shark (Mustelus lenticulatus) in an estuarine nursery.

PubMed

Francis, Malcolm P

2013-01-01

Juvenile rig (Mustelus lenticulatus) were internally tagged with acoustic transmitters and tracked with acoustic receivers deployed throughout two arms of Porirua Harbour, a small (7 km(2)) estuary in New Zealand. Ten rig were tracked for up to four months during summer-autumn to determine their spatial and temporal use of the habitat. The overall goal was to estimate the size of Marine Protected Areas required to protect rig nursery areas from direct human impacts. Rig showed clear site preferences, but those preferences varied among rig and over time. They spent most of their time in large basins and on shallow sand and mud flats around the margins, and avoided deep channels. Habitat range increased during autumn for many of the rig. Only one shark spent time in both harbour arms, indicating that there was little movement between the two. Rig home ranges were 2-7 km(2), suggesting that an effective MPA would need to cover the entire Porirua Harbour. They moved to outer harbour sites following some high river flow rates, and most left the harbour permanently during or soon after a river spike, suggesting that they were avoiding low salinity water. Rig showed strong diel movements during summer, although the diel pattern weakened in autumn. Persistent use of the same day and night sites indicates that diel movements are directed rather than random. Further research is required to determine the sizes of rig home ranges in larger harbours where nursery habitat is more extensive. Marine Protected Areas do not control land-based impacts such as accelerated sedimentation and heavy metal pollution, so integration of marine and terrestrial management tools across a range of government agencies is essential to fully protect nursery areas.

Temporal and Spatial Patterns of Habitat Use by Juveniles of a Small Coastal Shark (Mustelus lenticulatus) in an Estuarine Nursery

PubMed Central

Francis, Malcolm P.

2013-01-01

Juvenile rig (Mustelus lenticulatus) were internally tagged with acoustic transmitters and tracked with acoustic receivers deployed throughout two arms of Porirua Harbour, a small (7 km2) estuary in New Zealand. Ten rig were tracked for up to four months during summer–autumn to determine their spatial and temporal use of the habitat. The overall goal was to estimate the size of Marine Protected Areas required to protect rig nursery areas from direct human impacts. Rig showed clear site preferences, but those preferences varied among rig and over time. They spent most of their time in large basins and on shallow sand and mud flats around the margins, and avoided deep channels. Habitat range increased during autumn for many of the rig. Only one shark spent time in both harbour arms, indicating that there was little movement between the two. Rig home ranges were 2–7 km2, suggesting that an effective MPA would need to cover the entire Porirua Harbour. They moved to outer harbour sites following some high river flow rates, and most left the harbour permanently during or soon after a river spike, suggesting that they were avoiding low salinity water. Rig showed strong diel movements during summer, although the diel pattern weakened in autumn. Persistent use of the same day and night sites indicates that diel movements are directed rather than random. Further research is required to determine the sizes of rig home ranges in larger harbours where nursery habitat is more extensive. Marine Protected Areas do not control land-based impacts such as accelerated sedimentation and heavy metal pollution, so integration of marine and terrestrial management tools across a range of government agencies is essential to fully protect nursery areas. PMID:23437298

Multivariate information-theoretic measures reveal directed information structure and task relevant changes in fMRI connectivity.

PubMed

Lizier, Joseph T; Heinzle, Jakob; Horstmann, Annette; Haynes, John-Dylan; Prokopenko, Mikhail

2011-02-01

The human brain undertakes highly sophisticated information processing facilitated by the interaction between its sub-regions. We present a novel method for interregional connectivity analysis, using multivariate extensions to the mutual information and transfer entropy. The method allows us to identify the underlying directed information structure between brain regions, and how that structure changes according to behavioral conditions. This method is distinguished in using asymmetric, multivariate, information-theoretical analysis, which captures not only directional and non-linear relationships, but also collective interactions. Importantly, the method is able to estimate multivariate information measures with only relatively little data. We demonstrate the method to analyze functional magnetic resonance imaging time series to establish the directed information structure between brain regions involved in a visuo-motor tracking task. Importantly, this results in a tiered structure, with known movement planning regions driving visual and motor control regions. Also, we examine the changes in this structure as the difficulty of the tracking task is increased. We find that task difficulty modulates the coupling strength between regions of a cortical network involved in movement planning and between motor cortex and the cerebellum which is involved in the fine-tuning of motor control. It is likely these methods will find utility in identifying interregional structure (and experimentally induced changes in this structure) in other cognitive tasks and data modalities.

Handheld lasers allow efficient detection of fluorescent marked organisms in the field.

PubMed

Rice, Kevin B; Fleischer, Shelby J; De Moraes, Consuelo M; Mescher, Mark C; Tooker, John F; Gish, Moshe

2015-01-01

Marking organisms with fluorescent dyes and powders is a common technique used in ecological field studies that monitor movement of organisms to examine life history traits, behaviors, and population dynamics. External fluorescent marking is relatively inexpensive and can be readily employed to quickly mark large numbers of individuals; however, the ability to detect marked organisms in the field at night has been hampered by the limited detection distances provided by portable fluorescent ultraviolet lamps. In recent years, significant advances in LED lamp and laser technology have led to development of powerful, low-cost ultraviolet light sources. In this study, we evaluate the potential of these new technologies to improve detection of fluorescent-marked organisms in the field and to create new possibilities for tracking marked organisms in visually challenging environments such as tree canopies and aquatic habitats. Using handheld lasers, we document a method that provides a fivefold increase in detection distance over previously available technologies. This method allows easy scouting of tree canopies (from the ground), as well as shallow aquatic systems. This novel detection method for fluorescent-marked organisms thus promises to significantly enhance the use of fluorescent marking as a non-destructive technique for tracking organisms in natural environments, facilitating field studies that aim to document otherwise inaccessible aspects of the movement, behavior, and population dynamics of study organisms, including species with significant economic impacts or relevance for ecology and human health.

Decoding of human hand actions to handle missing limbs in neuroprosthetics.

PubMed

Belić, Jovana J; Faisal, A Aldo

2015-01-01

The only way we can interact with the world is through movements, and our primary interactions are via the hands, thus any loss of hand function has immediate impact on our quality of life. However, to date it has not been systematically assessed how coordination in the hand's joints affects every day actions. This is important for two fundamental reasons. Firstly, to understand the representations and computations underlying motor control "in-the-wild" situations, and secondly to develop smarter controllers for prosthetic hands that have the same functionality as natural limbs. In this work we exploit the correlation structure of our hand and finger movements in daily-life. The novelty of our idea is that instead of averaging variability out, we take the view that the structure of variability may contain valuable information about the task being performed. We asked seven subjects to interact in 17 daily-life situations, and quantified behavior in a principled manner using CyberGlove body sensor networks that, after accurate calibration, track all major joints of the hand. Our key findings are: (1) We confirmed that hand control in daily-life tasks is very low-dimensional, with four to five dimensions being sufficient to explain 80-90% of the variability in the natural movement data. (2) We established a universally applicable measure of manipulative complexity that allowed us to measure and compare limb movements across tasks. We used Bayesian latent variable models to model the low-dimensional structure of finger joint angles in natural actions. (3) This allowed us to build a naïve classifier that within the first 1000 ms of action initiation (from a flat hand start configuration) predicted which of the 17 actions was going to be executed-enabling us to reliably predict the action intention from very short-time-scale initial data, further revealing the foreseeable nature of hand movements for control of neuroprosthetics and tele operation purposes. (4) Using the Expectation-Maximization algorithm on our latent variable model permitted us to reconstruct with high accuracy (<5-6° MAE) the movement trajectory of missing fingers by simply tracking the remaining fingers. Overall, our results suggest the hypothesis that specific hand actions are orchestrated by the brain in such a way that in the natural tasks of daily-life there is sufficient redundancy and predictability to be directly exploitable for neuroprosthetics.

Performance adaptive training control strategy for recovering wrist movements in stroke patients: a preliminary, feasibility study

PubMed Central

2009-01-01

Background In the last two decades robot training in neuromotor rehabilitation was mainly focused on shoulder-elbow movements. Few devices were designed and clinically tested for training coordinated movements of the wrist, which are crucial for achieving even the basic level of motor competence that is necessary for carrying out ADLs (activities of daily life). Moreover, most systems of robot therapy use point-to-point reaching movements which tend to emphasize the pathological tendency of stroke patients to break down goal-directed movements into a number of jerky sub-movements. For this reason we designed a wrist robot with a range of motion comparable to that of normal subjects and implemented a self-adapting training protocol for tracking smoothly moving targets in order to facilitate the emergence of smoothness in the motor control patterns and maximize the recovery of the normal RoM (range of motion) of the different DoFs (degrees of Freedom). Methods The IIT-wrist robot is a 3 DoFs light exoskeleton device, with direct-drive of each DoF and a human-like range of motion for Flexion/Extension (FE), Abduction/Adduction (AA) and Pronation/Supination (PS). Subjects were asked to track a variable-frequency oscillating target using only one wrist DoF at time, in such a way to carry out a progressive splinting therapy. The RoM of each DoF was angularly scanned in a staircase-like fashion, from the "easier" to the "more difficult" angular position. An Adaptive Controller evaluated online performance parameters and modulated both the assistance and the difficulty of the task in order to facilitate smoother and more precise motor command patterns. Results Three stroke subjects volunteered to participate in a preliminary test session aimed at verify the acceptability of the device and the feasibility of the designed protocol. All of them were able to perform the required task. The wrist active RoM of motion was evaluated for each patient at the beginning and at the end of the test therapy session and the results suggest a positive trend. Conclusion The positive outcomes of the preliminary tests motivate the planning of a clinical trial and provide experimental evidence for defining appropriate inclusion/exclusion criteria. PMID:19968873

Electromyography and the study of sports movements: a review.

PubMed

Clarys, J P; Cabri, J

1993-10-01

Within electromyography (EMG), a particular specialty has been developed wherein the aim is to use EMG for the study of muscular function and co-ordination. This area of research is usually called kinesiological EMG. The general aims of kinesiological EMG are to analyse the function and co-ordination of muscles in different movements and postures, in healthy subjects as well as in the disabled, in skilled actions as well as during training, in humans as well as in animals, under laboratory conditions as well as during daily or vocational activities. This is often done by a combination of electromyographical and kinesiological or biomechanical measurement techniques. Because there are over 400 skeletal muscles in the human body and both irregular and complex involvement of the muscles may occur in neuromuscular diseases and in voluntary occupational or sports movements, it is impossible to sample all of the muscles of the entire body during the performance of complex motor skills. In addition, the measurement of kinesiological EMG in sport and specific field circumstances, such as the track and/or soccer field, the alpine ski slope, the swimming pool and the ice rink, demands a specific technological and methodological approach, adaptable to both the field and the sport circumstances. Sport movement techniques and skills, training approaches and methods, ergonomic verification of the human-machine interaction have, amongst others, a highly specialized muscular activity in common. The knowledge of such muscular action in all its aspects, its evaluation and its feedback should allow for the optimization of movement, of sports materials, of training possibilities and, in the end, of sports performance. Drawing conclusions from a review of the EMG research of 32 sports, covering over 100 different complex skills, including methodological approaches, is an impossible task. We have attempted to set standards concerning the EMG methodology at the beginning of this review. Electromyography and sports is a vast area and a complete review is impossible, as information will be found scattered in many different journals, including those on the sports sciences, ergonomics, biomechanics, applied physiology, in different congress proceedings, and so on. Consequently, many important aspects and possibly important publications may have been omitted from this review.

Robust control of dielectric elastomer diaphragm actuator for human pulse signal tracking

NASA Astrophysics Data System (ADS)

Ye, Zhihang; Chen, Zheng; Asmatulu, Ramazan; Chan, Hoyin

2017-08-01

Human pulse signal tracking is an emerging technology that is needed in traditional Chinese medicine. However, soft actuation with multi-frequency tracking capability is needed for tracking human pulse signal. Dielectric elastomer (DE) is one type of soft actuating that has great potential in human pulse signal tracking. In this paper, a DE diaphragm actuator was designed and fabricated to track human pulse pressure signal. A physics-based and control-oriented model has been developed to capture the dynamic behavior of DE diaphragm actuator. Using the physical model, an H-infinity robust control was designed for the actuator to reject high-frequency sensing noises and disturbances. The robust control was then implemented in real-time to track a multi-frequency signal, which verified the tracking capability and robustness of the control system. In the human pulse signal tracking test, a human pulse signal was measured at the City University of Hong Kong and then was tracked using DE actuator at Wichita State University in the US. Experimental results have verified that the DE actuator with its robust control is capable of tracking human pulse signal.

Accuracy and Reliability of the Kinect Version 2 for Clinical Measurement of Motor Function

PubMed Central

Kayser, Bastian; Mansow-Model, Sebastian; Verrel, Julius; Paul, Friedemann; Brandt, Alexander U.; Schmitz-Hübsch, Tanja

2016-01-01

Background The introduction of low cost optical 3D motion tracking sensors provides new options for effective quantification of motor dysfunction. Objective The present study aimed to evaluate the Kinect V2 sensor against a gold standard motion capture system with respect to accuracy of tracked landmark movements and accuracy and repeatability of derived clinical parameters. Methods Nineteen healthy subjects were concurrently recorded with a Kinect V2 sensor and an optical motion tracking system (Vicon). Six different movement tasks were recorded with 3D full-body kinematics from both systems. Tasks included walking in different conditions, balance and adaptive postural control. After temporal and spatial alignment, agreement of movements signals was described by Pearson’s correlation coefficient and signal to noise ratios per dimension. From these movement signals, 45 clinical parameters were calculated, including ranges of motions, torso sway, movement velocities and cadence. Accuracy of parameters was described as absolute agreement, consistency agreement and limits of agreement. Intra-session reliability of 3 to 5 measurement repetitions was described as repeatability coefficient and standard error of measurement for each system. Results Accuracy of Kinect V2 landmark movements was moderate to excellent and depended on movement dimension, landmark location and performed task. Signal to noise ratio provided information about Kinect V2 landmark stability and indicated larger noise behaviour in feet and ankles. Most of the derived clinical parameters showed good to excellent absolute agreement (30 parameters showed ICC(3,1) > 0.7) and consistency (38 parameters showed r > 0.7) between both systems. Conclusion Given that this system is low-cost, portable and does not require any sensors to be attached to the body, it could provide numerous advantages when compared to established marker- or wearable sensor based system. The Kinect V2 has the potential to be used as a reliable and valid clinical measurement tool. PMID:27861541

Preliminary Study of Ground Movement in Prone Landslide Area by Means of MAI InSAR A Case Study: Ciloto, West Java, Indonesia

NASA Astrophysics Data System (ADS)

Hayati, Noorlaila; Riedel, Björn; Niemeier, Wolfgang

2016-04-01

Ciloto is one of the most prone landslide hazard areas in Indonesia. Several landslides in 2012 and 2013 had been recorded in Ciloto and damaged infrastructure around the area. Investigating the history of ground movement along slope area before the landslide happened could support the hazard mitigation in the future. Considering to an efficient surveying method, space-borne SAR processing is the one appropriate way to monitor the phenomenon in past years. The purpose of this study is detecting ground movement using multi-temporal synthetic aperture radar images. We use 13 ALOS PALSAR images from 2007 to 2009 with combination Fine Beam Single (FBS) and Fine Beam Double (FBD) polarization to investigate the slow movement on slope topography. MAI (Multiple Aperture Interferometry) InSAR method is used to analyze the ground movement from both line-of-sight and along-track direction. We split the synthetic aperture into two-looking aperture so that along-track displacement could be created by the difference of forward-backward looking interferograms. With integration of both methods, we could more precisely detect the movement in prone landslide area and achieve two measurements produced by the same interferogram. However, InSAR requires smaller baseline and good temporal baseline between master and slave images to avoid decorellation. There are only several pairs that meet the condition of proper length and temporal baseline indeed the location is also on the agriculture area where is mostly covered by vegetation. The result for two years observation shows that there is insignificant slow movement along slope surface in Ciloto with -2 - -7 cm in range looks or line of sight and 9-40 cm in along track direction. Based on geometry SAR , the most visible detecting of displacement is on the north-west area due to utilization of ascending SAR images.

A review of vision-based motion analysis in sport.

PubMed

Barris, Sian; Button, Chris

2008-01-01

Efforts at player motion tracking have traditionally involved a range of data collection techniques from live observation to post-event video analysis where player movement patterns are manually recorded and categorized to determine performance effectiveness. Due to the considerable time required to manually collect and analyse such data, research has tended to focus only on small numbers of players within predefined playing areas. Whilst notational analysis is a convenient, practical and typically inexpensive technique, the validity and reliability of the process can vary depending on a number of factors, including how many observers are used, their experience, and the quality of their viewing perspective. Undoubtedly the application of automated tracking technology to team sports has been hampered because of inadequate video and computational facilities available at sports venues. However, the complex nature of movement inherent to many physical activities also represents a significant hurdle to overcome. Athletes tend to exhibit quick and agile movements, with many unpredictable changes in direction and also frequent collisions with other players. Each of these characteristics of player behaviour violate the assumptions of smooth movement on which computer tracking algorithms are typically based. Systems such as TRAKUS, SoccerMan, TRAKPERFORMANCE, Pfinder and Prozone all provide extrinsic feedback information to coaches and athletes. However, commercial tracking systems still require a fair amount of operator intervention to process the data after capture and are often limited by the restricted capture environments that can be used and the necessity for individuals to wear tracking devices. Whilst some online tracking systems alleviate the requirements of manual tracking, to our knowledge a completely automated system suitable for sports performance is not yet commercially available. Automatic motion tracking has been used successfully in other domains outside of elite sport performance, notably for surveillance in the military and security industry where automatic recognition of moving objects is achievable because identification of the objects is not necessary. The current challenge is to obtain appropriate video sequences that can robustly identify and label people over time, in a cluttered environment containing multiple interacting people. This problem is often compounded by the quality of video capture, the relative size and occlusion frequency of people, and also changes in illumination. Potential applications of an automated motion detection system are offered, such as: planning tactics and strategies; measuring team organisation; providing meaningful kinematic feedback; and objective measures of intervention effectiveness in team sports, which could benefit coaches, players, and sports scientists.

Quantitative evaluation of 3D mouse behaviors and motor function in the open-field after spinal cord injury using markerless motion tracking.

PubMed

Sheets, Alison L; Lai, Po-Lun; Fisher, Lesley C; Basso, D Michele

2013-01-01

Thousands of scientists strive to identify cellular mechanisms that could lead to breakthroughs in developing ameliorative treatments for debilitating neural and muscular conditions such as spinal cord injury (SCI). Most studies use rodent models to test hypotheses, and these are all limited by the methods available to evaluate animal motor function. This study's goal was to develop a behavioral and locomotor assessment system in a murine model of SCI that enables quantitative kinematic measurements to be made automatically in the open-field by applying markerless motion tracking approaches. Three-dimensional movements of eight naïve, five mild, five moderate, and four severe SCI mice were recorded using 10 cameras (100 Hz). Background subtraction was used in each video frame to identify the animal's silhouette, and the 3D shape at each time was reconstructed using shape-from-silhouette. The reconstructed volume was divided into front and back halves using k-means clustering. The animal's front Center of Volume (CoV) height and whole-body CoV speed were calculated and used to automatically classify animal behaviors including directed locomotion, exploratory locomotion, meandering, standing, and rearing. More detailed analyses of CoV height, speed, and lateral deviation during directed locomotion revealed behavioral differences and functional impairments in animals with mild, moderate, and severe SCI when compared with naïve animals. Naïve animals displayed the widest variety of behaviors including rearing and crossing the center of the open-field, the fastest speeds, and tallest rear CoV heights. SCI reduced the range of behaviors, and decreased speed (r = .70 p<.005) and rear CoV height (r = .65 p<.01) were significantly correlated with greater lesion size. This markerless tracking approach is a first step toward fundamentally changing how rodent movement studies are conducted. By providing scientists with sensitive, quantitative measurement methods, subjectivity and human error is reduced, potentially providing insights leading to breakthroughs in treating human disease.

Quantitative Evaluation of 3D Mouse Behaviors and Motor Function in the Open-Field after Spinal Cord Injury Using Markerless Motion Tracking

PubMed Central

Sheets, Alison L.; Lai, Po-Lun; Fisher, Lesley C.; Basso, D. Michele

2013-01-01

Thousands of scientists strive to identify cellular mechanisms that could lead to breakthroughs in developing ameliorative treatments for debilitating neural and muscular conditions such as spinal cord injury (SCI). Most studies use rodent models to test hypotheses, and these are all limited by the methods available to evaluate animal motor function. This study’s goal was to develop a behavioral and locomotor assessment system in a murine model of SCI that enables quantitative kinematic measurements to be made automatically in the open-field by applying markerless motion tracking approaches. Three-dimensional movements of eight naïve, five mild, five moderate, and four severe SCI mice were recorded using 10 cameras (100 Hz). Background subtraction was used in each video frame to identify the animal’s silhouette, and the 3D shape at each time was reconstructed using shape-from-silhouette. The reconstructed volume was divided into front and back halves using k-means clustering. The animal’s front Center of Volume (CoV) height and whole-body CoV speed were calculated and used to automatically classify animal behaviors including directed locomotion, exploratory locomotion, meandering, standing, and rearing. More detailed analyses of CoV height, speed, and lateral deviation during directed locomotion revealed behavioral differences and functional impairments in animals with mild, moderate, and severe SCI when compared with naïve animals. Naïve animals displayed the widest variety of behaviors including rearing and crossing the center of the open-field, the fastest speeds, and tallest rear CoV heights. SCI reduced the range of behaviors, and decreased speed (r = .70 p<.005) and rear CoV height (r = .65 p<.01) were significantly correlated with greater lesion size. This markerless tracking approach is a first step toward fundamentally changing how rodent movement studies are conducted. By providing scientists with sensitive, quantitative measurement methods, subjectivity and human error is reduced, potentially providing insights leading to breakthroughs in treating human disease. PMID:24058586

Eye tracking reveals a crucial role for facial motion in recognition of faces by infants

PubMed Central

Xiao, Naiqi G.; Quinn, Paul C.; Liu, Shaoying; Ge, Liezhong; Pascalis, Olivier; Lee, Kang

2015-01-01

Current knowledge about face processing in infancy comes largely from studies using static face stimuli, but faces that infants see in the real world are mostly moving ones. To bridge this gap, 3-, 6-, and 9-month-old Asian infants (N = 118) were familiarized with either moving or static Asian female faces and then their face recognition was tested with static face images. Eye tracking methodology was used to record eye movements during familiarization and test phases. The results showed a developmental change in eye movement patterns, but only for the moving faces. In addition, the more infants shifted their fixations across facial regions, the better was their face recognition, but only for the moving faces. The results suggest that facial movement influences the way faces are encoded from early in development. PMID:26010387

Measuring Memory and Attention to Preview in Motion.

PubMed

Jagacinski, Richard J; Hammond, Gordon M; Rizzi, Emanuele

2017-08-01

Objective Use perceptual-motor responses to perturbations to reveal the spatio-temporal detail of memory for the recent past and attention to preview when participants track a winding roadway. Background Memory of the recently passed roadway can be inferred from feedback control models of the participants' manual movement patterns. Similarly, attention to preview of the upcoming roadway can be inferred from feedforward control models of manual movement patterns. Method Perturbation techniques were used to measure these memory and attention functions. Results In a laboratory tracking task, the bandwidth of lateral roadway deviations was found to primarily influence memory for the past roadway rather than attention to preview. A secondary auditory/verbal/vocal memory task resulted in higher velocity error and acceleration error in the tracking task but did not affect attention to preview. Attention to preview was affected by the frequency pattern of sinusoidal perturbations of the roadway. Conclusion Perturbation techniques permit measurement of the spatio-temporal span of memory and attention to preview that affect tracking a winding roadway. They also provide new ways to explore goal-directed forgetting and spatially distributed attention in the context of movement. More generally, these techniques provide sensitive measures of individual differences in cognitive aspects of action. Application Models of driving behavior and assessment of driving skill may benefit from more detailed spatio-temporal measurement of attention to preview.

A unified dynamic neural field model of goal directed eye movements

NASA Astrophysics Data System (ADS)

Quinton, J. C.; Goffart, L.

2018-01-01

Primates heavily rely on their visual system, which exploits signals of graded precision based on the eccentricity of the target in the visual field. The interactions with the environment involve actively selecting and focusing on visual targets or regions of interest, instead of contemplating an omnidirectional visual flow. Eye-movements specifically allow foveating targets and track their motion. Once a target is brought within the central visual field, eye-movements are usually classified into catch-up saccades (jumping from one orientation or fixation to another) and smooth pursuit (continuously tracking a target with low velocity). Building on existing dynamic neural field equations, we introduce a novel model that incorporates internal projections to better estimate the current target location (associated to a peak of activity). Such estimate is then used to trigger an eye movement, leading to qualitatively different behaviours depending on the dynamics of the whole oculomotor system: (1) fixational eye-movements due to small variations in the weights of projections when the target is stationary, (2) interceptive and catch-up saccades when peaks build and relax on the neural field, (3) smooth pursuit when the peak stabilises near the centre of the field, the system reaching a fixed point attractor. Learning is nevertheless required for tracking a rapidly moving target, and the proposed model thus replicates recent results in the monkey, in which repeated exercise permits the maintenance of the target within in the central visual field at its current (here-and-now) location, despite the delays involved in transmitting retinal signals to the oculomotor neurons.

Using NextRAD sequencing to infer movement of herbivores among host plants.

PubMed

Fu, Zhen; Epstein, Brendan; Kelley, Joanna L; Zheng, Qi; Bergland, Alan O; Castillo Carrillo, Carmen I; Jensen, Andrew S; Dahan, Jennifer; Karasev, Alexander V; Snyder, William E

2017-01-01

Herbivores often move among spatially interspersed host plants, tracking high-quality resources through space and time. This dispersal is of particular interest for vectors of plant pathogens. Existing molecular tools to track such movement have yielded important insights, but often provide insufficient genetic resolution to infer spread at finer spatiotemporal scales. Here, we explore the use of Nextera-tagmented reductively-amplified DNA (NextRAD) sequencing to infer movement of a highly-mobile winged insect, the potato psyllid (Bactericera cockerelli), among host plants. The psyllid vectors the pathogen that causes zebra chip disease in potato (Solanum tuberosum), but understanding and managing the spread of this pathogen is limited by uncertainty about the insect's host plant(s) outside of the growing season. We identified 1,978 polymorphic loci among psyllids separated spatiotemporally on potato or in patches of bittersweet nightshade (S. dulcumara), a weedy plant proposed to be the source of potato-colonizing psyllids. A subset of the psyllids on potato exhibited genetic similarity to insects on nightshade, consistent with regular movement between these two host plants. However, a second subset of potato-collected psyllids was genetically distinct from those collected on bittersweet nightshade; this suggests that a currently unrecognized source, i.e., other nightshade patches or a third host-plant species, could be contributing to psyllid populations in potato. Oftentimes, dispersal of vectors of pathogens must be tracked at a fine scale in order to understand, predict, and manage disease spread. We demonstrate that emerging sequencing technologies that detect genome-wide SNPs of a vector can be used to infer such localized movement.

Phototropic solar tracking in sunflower plants: an integrative perspective

PubMed Central

Kutschera, Ulrich; Briggs, Winslow R.

2016-01-01

Background One of the best-known plant movements, phototropic solar tracking in sunflower (Helianthus annuus), has not yet been fully characterized. Two questions are still a matter of debate. (1) Is the adaptive significance solely an optimization of photosynthesis via the exposure of the leaves to the sun? (2) Is shade avoidance involved in this process? In this study, these concepts are discussed from a historical perspective and novel insights are provided. Scope and Methods Results from the primary literature on heliotropic growth movements led to the conclusion that these responses cease before anthesis, so that the flowering heads point to the East. Based on observations on 10-week-old plants, the diurnal East–West oscillations of the upper fifth of the growing stem and leaves in relation to the position of the sun (inclusive of nocturnal re-orientation) were documented, and photon fluence rates on the leaf surfaces on clear, cloudy and rainy days were determined. In addition, the light–response curve of net CO2 assimilation was determined on the upper leaves of the same batch of plants, and evidence for the occurrence of shade-avoidance responses in growing sunflower plants is summarized. Conclusions. Only elongating, vegetative sunflower shoots and the upper leaves perform phototropic solar tracking. Photon fluence response and CO2 assimilation measurements cast doubt on the ‘photosynthesis-optimization hypothesis’ as the sole explanation for the evolution of these plant movements. We suggest that the shade-avoidance response, which maximizes light-driven CO2 assimilation, plays a major role in solar tracking populations of competing sunflower plants, and an integrative scheme of these growth movements is provided. PMID:26420201

Complex versus simple ankle movement training in stroke using telerehabilitation: a randomized controlled trial.

PubMed

Deng, Huiqiong; Durfee, William K; Nuckley, David J; Rheude, Brandon S; Severson, Amy E; Skluzacek, Katie M; Spindler, Kristen K; Davey, Cynthia S; Carey, James R

2012-02-01

Telerehabilitation allows rehabilitative training to continue remotely after discharge from acute care and can include complex tasks known to create rich conditions for neural change. The purposes of this study were: (1) to explore the feasibility of using telerehabilitation to improve ankle dorsiflexion during the swing phase of gait in people with stroke and (2) to compare complex versus simple movements of the ankle in promoting behavioral change and brain reorganization. This study was a pilot randomized controlled trial. Training was done in the participant's home. Testing was done in separate research labs involving functional magnetic resonance imaging (fMRI) and multi-camera gait analysis. Sixteen participants with chronic stroke and impaired ankle dorsiflexion were assigned randomly to receive 4 weeks of telerehabilitation of the paretic ankle. Participants received either computerized complex movement training (track group) or simple movement training (move group). Behavioral changes were measured with the 10-m walk test and gait analysis using a motion capture system. Brain reorganization was measured with ankle tracking during fMRI. Dorsiflexion during gait was significantly larger in the track group compared with the move group. For fMRI, although the volume, percent volume, and intensity of cortical activation failed to show significant changes, the frequency count of the number of participants showing an increase versus a decrease in these values from pretest to posttest measurements was significantly different between the 2 groups, with the track group decreasing and the move group increasing. Limitations of this study were that no follow-up test was conducted and that a small sample size was used. The results suggest that telerehabilitation, emphasizing complex task training with the paretic limb, is feasible and can be effective in promoting further dorsiflexion in people with chronic stroke.

Phototropic solar tracking in sunflower plants: an integrative perspective.

PubMed

Kutschera, Ulrich; Briggs, Winslow R

2016-01-01

One of the best-known plant movements, phototropic solar tracking in sunflower (Helianthus annuus), has not yet been fully characterized. Two questions are still a matter of debate. (1) Is the adaptive significance solely an optimization of photosynthesis via the exposure of the leaves to the sun? (2) Is shade avoidance involved in this process? In this study, these concepts are discussed from a historical perspective and novel insights are provided. Results from the primary literature on heliotropic growth movements led to the conclusion that these responses cease before anthesis, so that the flowering heads point to the East. Based on observations on 10-week-old plants, the diurnal East-West oscillations of the upper fifth of the growing stem and leaves in relation to the position of the sun (inclusive of nocturnal re-orientation) were documented, and photon fluence rates on the leaf surfaces on clear, cloudy and rainy days were determined. In addition, the light-response curve of net CO2 assimilation was determined on the upper leaves of the same batch of plants, and evidence for the occurrence of shade-avoidance responses in growing sunflower plants is summarized. Only elongating, vegetative sunflower shoots and the upper leaves perform phototropic solar tracking. Photon fluence response and CO2 assimilation measurements cast doubt on the 'photosynthesis-optimization hypothesis' as the sole explanation for the evolution of these plant movements. We suggest that the shade-avoidance response, which maximizes light-driven CO2 assimilation, plays a major role in solar tracking populations of competing sunflower plants, and an integrative scheme of these growth movements is provided. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Human-like object tracking and gaze estimation with PKD android

PubMed Central

Wijayasinghe, Indika B.; Miller, Haylie L.; Das, Sumit K; Bugnariu, Nicoleta L.; Popa, Dan O.

2018-01-01

As the use of robots increases for tasks that require human-robot interactions, it is vital that robots exhibit and understand human-like cues for effective communication. In this paper, we describe the implementation of object tracking capability on Philip K. Dick (PKD) android and a gaze tracking algorithm, both of which further robot capabilities with regard to human communication. PKD's ability to track objects with human-like head postures is achieved with visual feedback from a Kinect system and an eye camera. The goal of object tracking with human-like gestures is twofold : to facilitate better human-robot interactions and to enable PKD as a human gaze emulator for future studies. The gaze tracking system employs a mobile eye tracking system (ETG; SensoMotoric Instruments) and a motion capture system (Cortex; Motion Analysis Corp.) for tracking the head orientations. Objects to be tracked are displayed by a virtual reality system, the Computer Assisted Rehabilitation Environment (CAREN; MotekForce Link). The gaze tracking algorithm converts eye tracking data and head orientations to gaze information facilitating two objectives: to evaluate the performance of the object tracking system for PKD and to use the gaze information to predict the intentions of the user, enabling the robot to understand physical cues by humans. PMID:29416193

Human-like object tracking and gaze estimation with PKD android

NASA Astrophysics Data System (ADS)

Wijayasinghe, Indika B.; Miller, Haylie L.; Das, Sumit K.; Bugnariu, Nicoleta L.; Popa, Dan O.

2016-05-01

As the use of robots increases for tasks that require human-robot interactions, it is vital that robots exhibit and understand human-like cues for effective communication. In this paper, we describe the implementation of object tracking capability on Philip K. Dick (PKD) android and a gaze tracking algorithm, both of which further robot capabilities with regard to human communication. PKD's ability to track objects with human-like head postures is achieved with visual feedback from a Kinect system and an eye camera. The goal of object tracking with human-like gestures is twofold: to facilitate better human-robot interactions and to enable PKD as a human gaze emulator for future studies. The gaze tracking system employs a mobile eye tracking system (ETG; SensoMotoric Instruments) and a motion capture system (Cortex; Motion Analysis Corp.) for tracking the head orientations. Objects to be tracked are displayed by a virtual reality system, the Computer Assisted Rehabilitation Environment (CAREN; MotekForce Link). The gaze tracking algorithm converts eye tracking data and head orientations to gaze information facilitating two objectives: to evaluate the performance of the object tracking system for PKD and to use the gaze information to predict the intentions of the user, enabling the robot to understand physical cues by humans.

Response of African Elephants (Loxodonta africana) to Seasonal Changes in Rainfall

PubMed Central

Garstang, Michael; Davis, Robert E.; Leggett, Keith; Frauenfeld, Oliver W.; Greco, Steven; Zipser, Edward; Peterson, Michael

2014-01-01

The factors that trigger sudden, seasonal movements of elephants are uncertain. We hypothesized that savannah elephant movements at the end of the dry season may be a response to their detection of distant thunderstorms. Nine elephants carrying Global Positioning System (GPS) receivers were tracked over seven years in the extremely dry and rugged region of northwestern Namibia. The transition date from dry to wet season conditions was determined annually from surface- and satellite-derived rainfall. The distance, location, and timing of rain events relative to the elephants were determined using the Tropical Rainfall Measurement Mission (TRMM) satellite precipitation observations. Behavioral Change Point Analysis (BCPA) was applied to four of these seven years demonstrating a response in movement of these elephants to intra- and inter-seasonal occurrences of rainfall. Statistically significant changes in movement were found prior to or near the time of onset of the wet season and before the occurrence of wet episodes within the dry season, although the characteristics of the movement changes are not consistent between elephants and years. Elephants in overlapping ranges, but following separate tracks, exhibited statistically valid non-random near-simultaneous changes in movements when rainfall was occurring more than 100 km from their location. While the environmental trigger that causes these excursions remains uncertain, rain-system generated infrasound, which can travel such distances and be detected by elephants, is a possible trigger for such changes in movement. PMID:25299514

Response of African elephants (Loxodonta africana) to seasonal changes in rainfall.

PubMed

Garstang, Michael; Davis, Robert E; Leggett, Keith; Frauenfeld, Oliver W; Greco, Steven; Zipser, Edward; Peterson, Michael

2014-01-01

The factors that trigger sudden, seasonal movements of elephants are uncertain. We hypothesized that savannah elephant movements at the end of the dry season may be a response to their detection of distant thunderstorms. Nine elephants carrying Global Positioning System (GPS) receivers were tracked over seven years in the extremely dry and rugged region of northwestern Namibia. The transition date from dry to wet season conditions was determined annually from surface- and satellite-derived rainfall. The distance, location, and timing of rain events relative to the elephants were determined using the Tropical Rainfall Measurement Mission (TRMM) satellite precipitation observations. Behavioral Change Point Analysis (BCPA) was applied to four of these seven years demonstrating a response in movement of these elephants to intra- and inter-seasonal occurrences of rainfall. Statistically significant changes in movement were found prior to or near the time of onset of the wet season and before the occurrence of wet episodes within the dry season, although the characteristics of the movement changes are not consistent between elephants and years. Elephants in overlapping ranges, but following separate tracks, exhibited statistically valid non-random near-simultaneous changes in movements when rainfall was occurring more than 100 km from their location. While the environmental trigger that causes these excursions remains uncertain, rain-system generated infrasound, which can travel such distances and be detected by elephants, is a possible trigger for such changes in movement.

Chemokinetic behavior of the infective third-stage larvae of Strongyloides ratti on a sodium chloride gradient.

PubMed

Tobata-Kudo, H; Higo, H; Koga, M; Tada, I

2000-09-01

The movements of the infective third-stage larvae (L3) of a rodent parasitic nematode Strongyloides ratti were examined on a sodium chloride (NaCl) gradient set up on agarose plates. The movements of larvae were followed by observing their tracks on the surface of the agarose. The direction of movement depended on the NaCl concentration at the point of their initial placement on the gradient. Larvae placed at between 230 and 370 mM NaCl tended to migrate towards areas of lower concentration. On the other hand, when placed at concentrations less than 20 mM NaCl, larvae tended to migrate initially towards higher concentrations but did not linger in areas where the concentration was over approximately 80 mM NaCl. It seems that S. ratti L3, tested in vitro, prefer regions with a concentration of NaCl below 80 mM NaCl. Two typical chemokinetic behaviors are seen; a unidirectional avoidance movement when initially placed in unfavorable environmental conditions and a random dispersal movement when placed within an area of favorable conditions. Track patterns were straight in the avoidance movement but included multiple changes of direction and loops in the dispersal movement. This study introduces an assay system suitable for studying chemokinetic behavior of larvae of Strongyloides ratti.

Computer-based analysis of general movements reveals stereotypies predicting cerebral palsy.

PubMed

Philippi, Heike; Karch, Dominik; Kang, Keun-Sun; Wochner, Katarzyna; Pietz, Joachim; Dickhaus, Hartmut; Hadders-Algra, Mijna

2014-10-01

To evaluate a kinematic paradigm of automatic general movements analysis in comparison to clinical assessment in 3-month-old infants and its prediction for neurodevelopmental outcome. Preterm infants at high risk (n=49; 26 males, 23 females) and term infants at low risk (n=18; eight males, 10 females) of developmental impairment were recruited from hospitals around Heidelberg, Germany. Kinematic analysis of general movements by magnet tracking and clinical video-based assessment of general movements were performed at 3 months of age. Neurodevelopmental outcome was evaluated at 2 years. By comparing the general movements of small samples of children with and without cerebral palsy (CP), we developed a kinematic paradigm typical for infants at risk of developing CP. We tested the validity of this paradigm as a tool to predict CP and neurodevelopmental impairment. Clinical assessment correctly identified almost all infants with neurodevelopmental impairment including CP, but did not predict if the infant would be affected by CP or not. The kinematic analysis, in particular the stereotypy score of arm movements, was an excellent predictor of CP, whereas stereotyped repetitive movements of the legs predicted any neurodevelopmental impairment. The automatic assessment of the stereotypy score by magnet tracking in 3-month-old spontaneously moving infants at high risk of developmental abnormalities allowed a valid detection of infants affected and unaffected by CP. © 2014 Mac Keith Press.

How young adults with autism spectrum disorder watch and interpret pragmatically complex scenes.

PubMed

Lönnqvist, Linda; Loukusa, Soile; Hurtig, Tuula; Mäkinen, Leena; Siipo, Antti; Väyrynen, Eero; Palo, Pertti; Laukka, Seppo; Mämmelä, Laura; Mattila, Marja-Leena; Ebeling, Hanna

2017-11-01

The aim of the current study was to investigate subtle characteristics of social perception and interpretation in high-functioning individuals with autism spectrum disorders (ASDs), and to study the relation between watching and interpreting. As a novelty, we used an approach that combined moment-by-moment eye tracking and verbal assessment. Sixteen young adults with ASD and 16 neurotypical control participants watched a video depicting a complex communication situation while their eye movements were tracked. The participants also completed a verbal task with questions related to the pragmatic content of the video. We compared verbal task scores and eye movements between groups, and assessed correlations between task performance and eye movements. Individuals with ASD had more difficulty than the controls in interpreting the video, and during two short moments there were significant group differences in eye movements. Additionally, we found significant correlations between verbal task scores and moment-level eye movement in the ASD group, but not among the controls. We concluded that participants with ASD had slight difficulties in understanding the pragmatic content of the video stimulus and attending to social cues, and that the connection between pragmatic understanding and eye movements was more pronounced for participants with ASD than for neurotypical participants.

Human-tracking strategies for a six-legged rescue robot based on distance and view

NASA Astrophysics Data System (ADS)

Pan, Yang; Gao, Feng; Qi, Chenkun; Chai, Xun

2016-03-01

Human tracking is an important issue for intelligent robotic control and can be used in many scenarios, such as robotic services and human-robot cooperation. Most of current human-tracking methods are targeted for mobile/tracked robots, but few of them can be used for legged robots. Two novel human-tracking strategies, view priority strategy and distance priority strategy, are proposed specially for legged robots, which enable them to track humans in various complex terrains. View priority strategy focuses on keeping humans in its view angle arrange with priority, while its counterpart, distance priority strategy, focuses on keeping human at a reasonable distance with priority. To evaluate these strategies, two indexes(average and minimum tracking capability) are defined. With the help of these indexes, the view priority strategy shows advantages compared with distance priority strategy. The optimization is done in terms of these indexes, which let the robot has maximum tracking capability. The simulation results show that the robot can track humans with different curves like square, circular, sine and screw paths. Two novel control strategies are proposed which specially concerning legged robot characteristics to solve human tracking problems more efficiently in rescue circumstances.

A MATLAB-based eye tracking control system using non-invasive helmet head restraint in the macaque.

PubMed

De Luna, Paolo; Mohamed Mustafar, Mohamed Faiz Bin; Rainer, Gregor

2014-09-30

Tracking eye position is vital for behavioral and neurophysiological investigations in systems and cognitive neuroscience. Infrared camera systems which are now available can be used for eye tracking without the need to surgically implant magnetic search coils. These systems are generally employed using rigid head fixation in monkeys, which maintains the eye in a constant position and facilitates eye tracking. We investigate the use of non-rigid head fixation using a helmet that constrains only general head orientation and allows some freedom of movement. We present a MATLAB software solution to gather and process eye position data, present visual stimuli, interact with various devices, provide experimenter feedback and store data for offline analysis. Our software solution achieves excellent timing performance due to the use of data streaming, instead of the traditionally employed data storage mode for processing analog eye position data. We present behavioral data from two monkeys, demonstrating that adequate performance levels can be achieved on a simple fixation paradigm and show how performance depends on parameters such as fixation window size. Our findings suggest that non-rigid head restraint can be employed for behavioral training and testing on a variety of gaze-dependent visual paradigms, reducing the need for rigid head restraint systems for some applications. While developed for macaque monkey, our system of course can work equally well for applications in human eye tracking where head constraint is undesirable. Copyright © 2014. Published by Elsevier B.V.

Connecting today's climates to future climate analogs to facilitate movement of species under climate change.

PubMed

Littlefield, Caitlin E; McRae, Brad H; Michalak, Julia L; Lawler, Joshua J; Carroll, Carlos

2017-12-01

Increasing connectivity is an important strategy for facilitating species range shifts and maintaining biodiversity in the face of climate change. To date, however, few researchers have included future climate projections in efforts to prioritize areas for increasing connectivity. We identified key areas likely to facilitate climate-induced species' movement across western North America. Using historical climate data sets and future climate projections, we mapped potential species' movement routes that link current climate conditions to analogous climate conditions in the future (i.e., future climate analogs) with a novel moving-window analysis based on electrical circuit theory. In addition to tracing shifting climates, the approach accounted for landscape permeability and empirically derived species' dispersal capabilities. We compared connectivity maps generated with our climate-change-informed approach with maps of connectivity based solely on the degree of human modification of the landscape. Including future climate projections in connectivity models substantially shifted and constrained priority areas for movement to a smaller proportion of the landscape than when climate projections were not considered. Potential movement, measured as current flow, decreased in all ecoregions when climate projections were included, particularly when dispersal was limited, which made climate analogs inaccessible. Many areas emerged as important for connectivity only when climate change was modeled in 2 time steps rather than in a single time step. Our results illustrate that movement routes needed to track changing climatic conditions may differ from those that connect present-day landscapes. Incorporating future climate projections into connectivity modeling is an important step toward facilitating successful species movement and population persistence in a changing climate. © 2017 Society for Conservation Biology.

Nonhuman Primate Studies to Advance Vision Science and Prevent Blindness.

PubMed

Mustari, Michael J

2017-12-01

Most primate behavior is dependent on high acuity vision. Optimal visual performance in primates depends heavily upon frontally placed eyes, retinal specializations, and binocular vision. To see an object clearly its image must be placed on or near the fovea of each eye. The oculomotor system is responsible for maintaining precise eye alignment during fixation and generating eye movements to track moving targets. The visual system of nonhuman primates has a similar anatomical organization and functional capability to that of humans. This allows results obtained in nonhuman primates to be applied to humans. The visual and oculomotor systems of primates are immature at birth and sensitive to the quality of binocular visual and eye movement experience during the first months of life. Disruption of postnatal experience can lead to problems in eye alignment (strabismus), amblyopia, unsteady gaze (nystagmus), and defective eye movements. Recent studies in nonhuman primates have begun to discover the neural mechanisms associated with these conditions. In addition, genetic defects that target the retina can lead to blindness. A variety of approaches including gene therapy, stem cell treatment, neuroprosthetics, and optogenetics are currently being used to restore function associated with retinal diseases. Nonhuman primates often provide the best animal model for advancing fundamental knowledge and developing new treatments and cures for blinding diseases. © The Author(s) 2017. Published by Oxford University Press on behalf of the National Academy of Sciences. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Three-dimensional data-tracking dynamic optimization simulations of human locomotion generated by direct collocation.

PubMed

Lin, Yi-Chung; Pandy, Marcus G

2017-07-05

The aim of this study was to perform full-body three-dimensional (3D) dynamic optimization simulations of human locomotion by driving a neuromusculoskeletal model toward in vivo measurements of body-segmental kinematics and ground reaction forces. Gait data were recorded from 5 healthy participants who walked at their preferred speeds and ran at 2m/s. Participant-specific data-tracking dynamic optimization solutions were generated for one stride cycle using direct collocation in tandem with an OpenSim-MATLAB interface. The body was represented as a 12-segment, 21-degree-of-freedom skeleton actuated by 66 muscle-tendon units. Foot-ground interaction was simulated using six contact spheres under each foot. The dynamic optimization problem was to find the set of muscle excitations needed to reproduce 3D measurements of body-segmental motions and ground reaction forces while minimizing the time integral of muscle activations squared. Direct collocation took on average 2.7±1.0h and 2.2±1.6h of CPU time, respectively, to solve the optimization problems for walking and running. Model-computed kinematics and foot-ground forces were in good agreement with corresponding experimental data while the calculated muscle excitation patterns were consistent with measured EMG activity. The results demonstrate the feasibility of implementing direct collocation on a detailed neuromusculoskeletal model with foot-ground contact to accurately and efficiently generate 3D data-tracking dynamic optimization simulations of human locomotion. The proposed method offers a viable tool for creating feasible initial guesses needed to perform predictive simulations of movement using dynamic optimization theory. The source code for implementing the model and computational algorithm may be downloaded at http://simtk.org/home/datatracking. Copyright © 2017 Elsevier Ltd. All rights reserved.

Real-time movement detection and analysis for video surveillance applications

NASA Astrophysics Data System (ADS)

Hueber, Nicolas; Hennequin, Christophe; Raymond, Pierre; Moeglin, Jean-Pierre

2014-06-01

Pedestrian movement along critical infrastructures like pipes, railways or highways, is of major interest in surveillance applications as well as its behavior in urban environment. The goal is to anticipate illicit or dangerous human activities. For this purpose, we propose an all-in-one small autonomous system which delivers high level statistics and reports alerts in specific cases. This situational awareness project leads us to manage efficiently the scene by performing movement analysis. A dynamic background extraction algorithm is developed to reach the degree of robustness against natural and urban environment perturbations and also to match the embedded implementation constraints. When changes are detected in the scene, specific patterns are applied to detect and highlight relevant movements. Depending on the applications, specific descriptors can be extracted and fused in order to reach a high level of interpretation. In this paper, our approach is applied to two operational use cases: pedestrian urban statistics and railway surveillance. In the first case, a grid of prototypes is deployed over a city centre to collect pedestrian movement statistics up to a macroscopic level of analysis. The results demonstrate the relevance of the delivered information; in particular, the flow density map highlights pedestrian preferential paths along the streets. In the second case, one prototype is set next to high speed train tracks to secure the area. The results exhibit a low false alarm rate and assess our approach of a large sensor network for delivering a precise operational picture without overwhelming a supervisor.

The effect of changes in habitat conditions on the movement of juvenile Snail Kites Rostrhamus sociabilis

USGS Publications Warehouse

Bowling, Andrea C.; Martin, Julien; Kitchens, Wiley M.

2012-01-01

The degradation of habitats due to human activities is a major topic of interest for the conservation and management of wild populations. There is growing evidence that the Florida Everglades ecosystem continues to suffer from habitat degradation. After a period of recovery in the 1990s, the Snail Kite Rostrhamus sociabilis population suffered a substantial decline in 2001 and has not recovered since. Habitat degradation has been suggested as one of the primary reasons for this lack of recovery. As a consequence of the continued degradation of the Everglades, we hypothesized that this would have led to increased movement of juvenile Kites over time, as a consequence of the need to find more favourable habitat. We used multistate mark-recapture models to compare between-site movement probabilities of juvenile Snail Kites in the 1990s (1992–95; which corresponds to the period before the decline) and 2000s (2003–06; after the decline). Our analyses were based on an extensive radiotelemetry study (266 birds tracked monthly over the entire state of Florida for a total period of 6 years) and considered factors such as sex and age of marked individuals. There was evidence of increased movement of juvenile Snail Kites during the post-decline period from most of the wetland regions used historically by Kites. Higher movement rates may contribute to an increase in the probability of mortality of young individuals and could contribute to the observed declines.

Functional and Structural Correlates of Motor Speed in the Cerebellar Anterior Lobe

PubMed Central

Wenzel, Uwe; Taubert, Marco; Ragert, Patrick; Krug, Jürgen; Villringer, Arno

2014-01-01

In athletics, motor performance is determined by different abilities such as technique, endurance, strength and speed. Based on animal studies, motor speed is thought to be encoded in the basal ganglia, sensorimotor cortex and the cerebellum. The question arises whether there is a unique structural feature in the human brain, which allows “power athletes” to perform a simple foot movement significantly faster than “endurance athletes”. We acquired structural and functional brain imaging data from 32 track-and-field athletes. The study comprised of 16 “power athletes” requiring high speed foot movements (sprinters, jumpers, throwers) and 16 endurance athletes (distance runners) which in contrast do not require as high speed foot movements. Functional magnetic resonance imaging (fMRI) was used to identify speed specific regions of interest in the brain during fast and slow foot movements. Anatomical MRI scans were performed to assess structural grey matter volume differences between athletes groups (voxel based morphometry). We tested maximum movement velocity of plantarflexion (PF-Vmax) and acquired electromyographical activity of the lateral and medial gastrocnemius muscle. Behaviourally, a significant difference between the two groups of athletes was noted in PF-Vmax and fMRI indicates that fast plantarflexions are accompanied by increased activity in the cerebellar anterior lobe. The same region indicates increased grey matter volume for the power athletes compared to the endurance counterparts. Our results suggest that speed-specific neuro-functional and -structural differences exist between power and endurance athletes in the peripheral and central nervous system. PMID:24800742

US93 bighorn sheep study : distribution and trans-highway movements of desert bighorn sheep in northwestern Arizona.

DOT National Transportation Integrated Search

2007-01-01

Desert bighorn sheep were monitored via satellite telemetry, ground observations, and : track beds between 2004 and 2006, primarily to determine distribution and movements : relative to mileposts (MP) 3 to 17 of U.S. Highway 93 in the Black Mountains...

The LEAP™ Gesture Interface Device and Take-Home Laparoscopic Simulators: A Study of Construct and Concurrent Validity.

PubMed

Partridge, Roland W; Brown, Fraser S; Brennan, Paul M; Hennessey, Iain A M; Hughes, Mark A

2016-02-01

To assess the potential of the LEAP™ infrared motion tracking device to map laparoscopic instrument movement in a simulated environment. Simulator training is optimized when augmented by objective performance feedback. We explore the potential LEAP has to provide this in a way compatible with affordable take-home simulators. LEAP and the previously validated InsTrac visual tracking tool mapped expert and novice performances of a standardized simulated laparoscopic task. Ability to distinguish between the 2 groups (construct validity) and correlation between techniques (concurrent validity) were the primary outcome measures. Forty-three expert and 38 novice performances demonstrated significant differences in LEAP-derived metrics for instrument path distance (P < .001), speed (P = .002), acceleration (P < .001), motion smoothness (P < .001), and distance between the instruments (P = .019). Only instrument path distance demonstrated a correlation between LEAP and InsTrac tracking methods (novices: r = .663, P < .001; experts: r = .536, P < .001). Consistency of LEAP tracking was poor (average % time hands not tracked: 31.9%). The LEAP motion device is able to track the movement of hands using instruments in a laparoscopic box simulator. Construct validity is demonstrated by its ability to distinguish novice from expert performances. Only time and instrument path distance demonstrated concurrent validity with an existing tracking method however. A number of limitations to the tracking method used by LEAP have been identified. These need to be addressed before it can be considered an alternative to visual tracking for the delivery of objective performance metrics in take-home laparoscopic simulators. © The Author(s) 2015.

Seasonal movements, migratory behavior, and site fidelity of West Indian manatees along the Atlantic coast of the United States

USGS Publications Warehouse

Deutsch, C.J.; Reid, J.P.; Bonde, R.K.; Easton, Dean E.; Kochman, H.I.; O'Shea, T.J.

2003-01-01

The West Indian manatee (Trichechus manatus) is endangered by human activities throughout its range, including the U.S. Atlantic coast where habitat degradation from coastal development and manatee deaths from watercraft collisions have been particularly severe. We radio-tagged and tracked 78 manatees along the east coast of Florida and Georgia over a 12-year period (1986-1998). Our goals were to characterize the seasonal movements, migratory behavior, and site fidelity of manatees in this region in order to provide information for the development of effective conservation strategies. Most study animals were tracked remotely with the Argos satellite system, which yielded a mean (SD) of 3.7 (1.6) locations per day; all were regularly tracked in the field using conventional radiotelemetry methods. The combined data collection effort yielded >93,000 locations over nearly 32,000 tag-days. The median duration of tracking was 8.3 months per individual, but numerous manatees were tracked over multiple years (max = 6.8 years). Most manatees migrated seasonally over large distances between a northerly warm-season range and a southerly winter range (median one-way distance = 280 km, max = 830 km), but 12% of individuals were resident in a relatively small area (2,300 km of coastline between southeastern Florida and Rhode Island. No study animals journeyed to the Gulf coast of Florida. Regions heavily utilized by tagged manatees included: Fernandina Beach, FL to Brunswick, GA in the warm season; northern Biscayne Bay to Port Everglades, FL in the winter; and central coastal Florida, especially the Banana River and northern Indian River lagoons, in all seasons. Daily travel rate, defined as the distance between successive mean daily locations, averaged 2.5 km (SD = 1.7), but this varied with season, migratory pattern, and sex. Adult males traveled a significantly greater distance per day than did adult females for most of the warm season, which corresponded closely with the principal period of breeding activity, but there was no difference between the sexes in daily travel rate during the winter. The timing of seasonal migrations differed markedly between geographic regions. Most long-distance movements in the southern half of the study area occurred between November and March in response to changing temperatures, whereas most migrations in the northern region took place during the warmer, non-winter months. Manatees left their warm-season range in central Florida in response to cold fronts that dropped water temperatures by an average of 2.0??C over the 24-hr period preceding departure. Water temperature at departure from the warm-season range averaged 19??C, but varied among individuals (16-22??C) and was not related to body size or female reproductive status. The presence of industrial warm-water effluents permitted many manatees to overwinter north of their historic winter range, and for some migrants this delayed autumn migrations and facilitated earlier spring migrations. Southward autumn and northward spring migrations lasted an average of 10 and 15 days at mean rates of 33.5 (SD = 7.6) and 27.3 (SD = 10.5) km/day, respectively. The highest rate of travel during migration was 87 km/day (3.6 km/hr) during winter. Manatees overwintering in southeastern Florida often traveled north during mild weather - sometimes reaching their warm-season range - only to return south again with the next major cold front. Manatees were consistent in their seasonal movement patterns across years and showed strong fidelity, to warm-season and winter ranges. Within a season, individuals usually occupied only 1 or 2 core use areas that encompassed about 90% of daily locations. Most manatees returned faithfully to the same seasonal ranges year after year (median distance between range centers was <5 km between years). Seasonal movements of 4 immature manatees tracked as calves with their mothers

Comparison of Urban Human Movements Inferring from Multi-Source Spatial-Temporal Data

NASA Astrophysics Data System (ADS)

Cao, Rui; Tu, Wei; Cao, Jinzhou; Li, Qingquan

2016-06-01

The quantification of human movements is very hard because of the sparsity of traditional data and the labour intensive of the data collecting process. Recently, much spatial-temporal data give us an opportunity to observe human movement. This research investigates the relationship of city-wide human movements inferring from two types of spatial-temporal data at traffic analysis zone (TAZ) level. The first type of human movement is inferred from long-time smart card transaction data recording the boarding actions. The second type of human movement is extracted from citywide time sequenced mobile phone data with 30 minutes interval. Travel volume, travel distance and travel time are used to measure aggregated human movements in the city. To further examine the relationship between the two types of inferred movements, the linear correlation analysis is conducted on the hourly travel volume. The obtained results show that human movements inferred from smart card data and mobile phone data have a correlation of 0.635. However, there are still some non-ignorable differences in some special areas. This research not only reveals the citywide spatial-temporal human dynamic but also benefits the understanding of the reliability of the inference of human movements with big spatial-temporal data.

APM_GUI: analyzing particle movement on the cell membrane and determining confinement.

PubMed

Menchón, Silvia A; Martín, Mauricio G; Dotti, Carlos G

2012-02-20

Single-particle tracking is a powerful tool for tracking individual particles with high precision. It provides useful information that allows the study of diffusion properties as well as the dynamics of movement. Changes in particle movement behavior, such as transitions between Brownian motion and temporary confinement, can reveal interesting biophysical interactions. Although useful applications exist to determine the paths of individual particles, only a few software implementations are available to analyze these data, and these implementations are generally not user-friendly and do not have a graphical interface,. Here, we present APM_GUI (Analyzing Particle Movement), which is a MatLab-implemented application with a Graphical User Interface. This user-friendly application detects confined movement considering non-random confinement when a particle remains in a region longer than a Brownian diffusant would remain. In addition, APM_GUI exports the results, which allows users to analyze this information using software that they are familiar with. APM_GUI provides an open-source tool that quantifies diffusion coefficients and determines whether trajectories have non-random confinements. It also offers a simple and user-friendly tool that can be used by individuals without programming skills.

Wearable kinesthetic system for capturing and classifying upper limb gesture in post-stroke rehabilitation.

PubMed

Tognetti, Alessandro; Lorussi, Federico; Bartalesi, Raphael; Quaglini, Silvana; Tesconi, Mario; Zupone, Giuseppe; De Rossi, Danilo

2005-03-02

BACKGROUND: Monitoring body kinematics has fundamental relevance in several biological and technical disciplines. In particular the possibility to exactly know the posture may furnish a main aid in rehabilitation topics. In the present work an innovative and unobtrusive garment able to detect the posture and the movement of the upper limb has been introduced, with particular care to its application in post stroke rehabilitation field by describing the integration of the prototype in a healthcare service. METHODS: This paper deals with the design, the development and implementation of a sensing garment, from the characterization of innovative comfortable and diffuse sensors we used to the methodologies employed to gather information on the posture and movement which derive from the entire garments. Several new algorithms devoted to the signal acquisition, the treatment and posture and gesture reconstruction are introduced and tested. RESULTS: Data obtained by means of the sensing garment are analyzed and compared with the ones recorded using a traditional movement tracking system. CONCLUSION: The main results treated in this work are summarized and remarked. The system was compared with a commercial movement tracking system (a set of electrogoniometers) and it performed the same accuracy in detecting upper limb postures and movements.

The fabrication of a customized occlusal splint based on the merging of dynamic jaw tracking records, cone beam computed tomography, and CAD-CAM digital impression.

PubMed

Aslanidou, Katerina; Kau, Chung How; Vlachos, Christos; Saleh, Tayem Abou

2017-01-01

The aim of this case report was to present the procedure of fabricating a customized occlusal splint, through a revolutionary software that combines cone beam computed tomography (CBCT) with jaw motion tracking (JMT) data and superimposes a digital impression. The case report was conducted on a 46-year-old female patient diagnosed with the temporomandibular disorder. A CBCT scan and an optical impression were obtained. The range of the patient's mandibular movements was captured with a JMT device. The data were combined in the SICAT software (SICAT, Sirona, Bonn, Germany). The software enabled the visualization of patient-specific mandibular movements and provided a real dynamic anatomical evaluation of the condylar position in the glenoid fossa. After the assessment of the range of movements during opening, protrusion, and lateral movements all the data were sent to SICAT and a customized occlusal splint was manufactured. The SICAT software provides a three-dimensional real-dynamic simulation of mandibular movements relative to the patient-specific anatomy of the jaw; thus, it opens new possibilities and potentials for the management of temporomandibular disorders.

A Statistical Physics Perspective to Understand Social Visual Attention in Autism Spectrum Disorder.

PubMed

Liberati, Alessio; Fadda, Roberta; Doneddu, Giuseppe; Congiu, Sara; Javarone, Marco A; Striano, Tricia; Chessa, Alessandro

2017-08-01

This study investigated social visual attention in children with Autism Spectrum Disorder (ASD) and with typical development (TD) in the light of Brockmann and Geisel's model of visual attention. The probability distribution of gaze movements and clustering of gaze points, registered with eye-tracking technology, was studied during a free visual exploration of a gaze stimulus. A data-driven analysis of the distribution of eye movements was chosen to overcome any possible methodological problems related to the subjective expectations of the experimenters about the informative contents of the image in addition to a computational model to simulate group differences. Analysis of the eye-tracking data indicated that the scanpaths of children with TD and ASD were characterized by eye movements geometrically equivalent to Lévy flights. Children with ASD showed a higher frequency of long saccadic amplitudes compared with controls. A clustering analysis revealed a greater dispersion of eye movements for these children. Modeling of the results indicated higher values of the model parameter modulating the dispersion of eye movements for children with ASD. Together, the experimental results and the model point to a greater dispersion of gaze points in ASD.

Implicit false-belief processing in the human brain.

PubMed

Schneider, Dana; Slaughter, Virginia P; Becker, Stefanie I; Dux, Paul E

2014-11-01

Eye-movement patterns in 'Sally-Anne' tasks reflect humans' ability to implicitly process the mental states of others, particularly false-beliefs - a key theory of mind (ToM) operation. It has recently been proposed that an efficient ToM system, which operates in the absence of awareness (implicit ToM, iToM), subserves the analysis of belief-like states. This contrasts to consciously available belief processing, performed by the explicit ToM system (eToM). The frontal, temporal and parietal cortices are engaged when humans explicitly 'mentalize' about others' beliefs. However, the neural underpinnings of implicit false-belief processing and the extent to which they draw on networks involved in explicit general-belief processing are unknown. Here, participants watched 'Sally-Anne' movies while fMRI and eye-tracking measures were acquired simultaneously. Participants displayed eye-movements consistent with implicit false-belief processing. After independently localizing the brain areas involved in explicit general-belief processing, only the left anterior superior temporal sulcus and precuneus revealed greater blood-oxygen-level-dependent activity for false- relative to true-belief trials in our iToM paradigm. No such difference was found for the right temporal-parietal junction despite significant activity in this area. These findings fractionate brain regions that are associated with explicit general ToM reasoning and false-belief processing in the absence of awareness. Copyright © 2014 Elsevier Inc. All rights reserved.

Straight as an arrow: humpback whales swim constant course tracks during long-distance migration

PubMed Central

Horton, Travis W.; Holdaway, Richard N.; Zerbini, Alexandre N.; Hauser, Nan; Garrigue, Claire; Andriolo, Artur; Clapham, Phillip J.

2011-01-01

Humpback whale seasonal migrations, spanning greater than 6500 km of open ocean, demonstrate remarkable navigational precision despite following spatially and temporally distinct migration routes. Satellite-monitored radio tag-derived humpback whale migration tracks in both the South Atlantic and South Pacific include constant course segments of greater than 200 km, each spanning several days of continuous movement. The whales studied here maintain these directed movements, often with better than 1° precision, despite the effects of variable sea-surface currents. Such remarkable directional precision is difficult to explain by established models of directional orientation, suggesting that alternative compass mechanisms should be explored. PMID:21508023

Straight as an arrow: humpback whales swim constant course tracks during long-distance migration.

PubMed

Horton, Travis W; Holdaway, Richard N; Zerbini, Alexandre N; Hauser, Nan; Garrigue, Claire; Andriolo, Artur; Clapham, Phillip J

2011-10-23

Humpback whale seasonal migrations, spanning greater than 6500 km of open ocean, demonstrate remarkable navigational precision despite following spatially and temporally distinct migration routes. Satellite-monitored radio tag-derived humpback whale migration tracks in both the South Atlantic and South Pacific include constant course segments of greater than 200 km, each spanning several days of continuous movement. The whales studied here maintain these directed movements, often with better than 1° precision, despite the effects of variable sea-surface currents. Such remarkable directional precision is difficult to explain by established models of directional orientation, suggesting that alternative compass mechanisms should be explored.

A deterministic mathematical model for bidirectional excluded flow with Langmuir kinetics.

PubMed

Zarai, Yoram; Margaliot, Michael; Tuller, Tamir

2017-01-01

In many important cellular processes, including mRNA translation, gene transcription, phosphotransfer, and intracellular transport, biological "particles" move along some kind of "tracks". The motion of these particles can be modeled as a one-dimensional movement along an ordered sequence of sites. The biological particles (e.g., ribosomes or RNAPs) have volume and cannot surpass one another. In some cases, there is a preferred direction of movement along the track, but in general the movement may be bidirectional, and furthermore the particles may attach or detach from various regions along the tracks. We derive a new deterministic mathematical model for such transport phenomena that may be interpreted as a dynamic mean-field approximation of an important model from mechanical statistics called the asymmetric simple exclusion process (ASEP) with Langmuir kinetics. Using tools from the theory of monotone dynamical systems and contraction theory we show that the model admits a unique steady-state, and that every solution converges to this steady-state. Furthermore, we show that the model entrains (or phase locks) to periodic excitations in any of its forward, backward, attachment, or detachment rates. We demonstrate an application of this phenomenological transport model for analyzing ribosome drop off in mRNA translation.

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

Lyn, Rodney K.; Department of Chemistry, University of Ottawa, Ottawa; Kennedy, David C.

Research highlights: {yields} Hepatitis C virus uses lipid droplets (LD) onto which HCV core proteins bind. {yields} HCV core proteins on LDs facilitate viral particle assembly. {yields} We used a novel combination of CARS, two-photon fluorescence, and DIC microscopies. {yields} Particle tracking experiments show that core slowly affects LD localization. {yields} Particle tracking measured the change in speed and directionality of LD movement. -- Abstract: The hepatitis C virus (HCV) is a global health problem, with limited treatment options and no vaccine available. HCV uses components of the host cell to proliferate, including lipid droplets (LD) onto which HCV coremore » proteins bind and facilitate viral particle assembly. We have measured the dynamics of HCV core protein-mediated changes in LDs and rates of LD movement on microtubules using a combination of coherent anti-Stokes Raman scattering (CARS), two-photon fluorescence (TPF), and differential interference contrast (DIC) microscopies. Results show that the HCV core protein induces rapid increases in LD size. Particle tracking experiments show that HCV core protein slowly affects LD localization by controlling the directionality of LD movement on microtubules. These dynamic processes ultimately aid HCV in propagating and the molecules and interactions involved represent novel targets for potential therapeutic intervention.« less

Momentum Biased Performance of LAPAN-A3 Satellite for Multispectral Pushbroom Imager Operation

NASA Astrophysics Data System (ADS)

Utama, S.; Saifudin, M. A.; Mukhayadi, M.

2018-05-01

One of LAPAN-A3 satellite’s missions is for earth observation using multispectral pushbroom imager. This mission needs a stable and accurate attitude to capture any area of interest. To accomplish the mission LAPAN-A3 satellite use momentum biased attitude control. The satellite use magnetic torquers to control the angular momentum vector and a reaction wheel to spin the satellite to remain nadir pointing. When the satellite spinning there are nutation and precession occurred. This paper observes attitude accuracy and stability due to nutation and precession of the satellite’s momentum and the effect to pushbroom imager operation. Nutation observed with 0.28° amplitude and 73 seconds period, and precession observed with 1° amplitude and 92 minutes period. This nutation and precession profile will lead to 2.6° attitude accuracy and maximum movement on ground track 0.055 km/s in along track direction and 0.259 km/s (0.026°/s) in cross track direction. Both of attitude accuracy and movement are outperformed the limitation. However due to satellite movement in orbit there is still blurring effect on the imager.