Evaluating Suit Fit Using Performance Degradation

NASA Technical Reports Server (NTRS)

Margerum, Sarah E.; Cowley, Matthew; Harvill, Lauren; Benson, Elizabeth; Rajulu, Sudhakar

2011-01-01

The Mark III suit has multiple sizes of suit components (arm, leg, and gloves) as well as sizing inserts to tailor the fit of the suit to an individual. This study sought to determine a way to identify the point an ideal suit fit transforms into a bad fit and how to quantify this breakdown using mobility-based physical performance data. This study examined the changes in human physical performance via degradation of the elbow and wrist range of motion of the planetary suit prototype (Mark III) with respect to changes in sizing and as well as how to apply that knowledge to suit sizing options and improvements in suit fit. The methods implemented in this study focused on changes in elbow and wrist mobility due to incremental suit sizing modifications. This incremental sizing was within a range that included both optimum and poor fit. Suited range of motion data was collected using a motion analysis system for nine isolated and functional tasks encompassing the elbow and wrist joints. A total of four subjects were tested with motions involving both arms simultaneously as well as the right arm only. The results were then compared across sizing configurations. The results of this study indicate that range of motion may be used as a viable parameter to quantify at what stage suit sizing causes a detriment in performance; however the human performance decrement appeared to be based on the interaction of multiple joints along a limb, not a single joint angle. The study was able to identify a preliminary method to quantify the impact of size on performance and to develop a means to gauge tolerances around optimal size. More work is needed to improve the assessment of optimal fit and to compensate for multiple joint interactions.

Adaptive vehicle motion estimation and prediction

NASA Astrophysics Data System (ADS)

Zhao, Liang; Thorpe, Chuck E.

1999-01-01

Accurate motion estimation and reliable maneuver prediction enable an automated car to react quickly and correctly to the rapid maneuvers of the other vehicles, and so allow safe and efficient navigation. In this paper, we present a car tracking system which provides motion estimation, maneuver prediction and detection of the tracked car. The three strategies employed - adaptive motion modeling, adaptive data sampling, and adaptive model switching probabilities - result in an adaptive interacting multiple model algorithm (AIMM). The experimental results on simulated and real data demonstrate that our tracking system is reliable, flexible, and robust. The adaptive tracking makes the system intelligent and useful in various autonomous driving tasks.

Naturalistic FMRI mapping reveals superior temporal sulcus as the hub for the distributed brain network for social perception.

PubMed

Lahnakoski, Juha M; Glerean, Enrico; Salmi, Juha; Jääskeläinen, Iiro P; Sams, Mikko; Hari, Riitta; Nummenmaa, Lauri

2012-01-01

Despite the abundant data on brain networks processing static social signals, such as pictures of faces, the neural systems supporting social perception in naturalistic conditions are still poorly understood. Here we delineated brain networks subserving social perception under naturalistic conditions in 19 healthy humans who watched, during 3-T functional magnetic resonance imaging (fMRI), a set of 137 short (approximately 16 s each, total 27 min) audiovisual movie clips depicting pre-selected social signals. Two independent raters estimated how well each clip represented eight social features (faces, human bodies, biological motion, goal-oriented actions, emotion, social interaction, pain, and speech) and six filler features (places, objects, rigid motion, people not in social interaction, non-goal-oriented action, and non-human sounds) lacking social content. These ratings were used as predictors in the fMRI analysis. The posterior superior temporal sulcus (STS) responded to all social features but not to any non-social features, and the anterior STS responded to all social features except bodies and biological motion. We also found four partially segregated, extended networks for processing of specific social signals: (1) a fronto-temporal network responding to multiple social categories, (2) a fronto-parietal network preferentially activated to bodies, motion, and pain, (3) a temporo-amygdalar network responding to faces, social interaction, and speech, and (4) a fronto-insular network responding to pain, emotions, social interactions, and speech. Our results highlight the role of the pSTS in processing multiple aspects of social information, as well as the feasibility and efficiency of fMRI mapping under conditions that resemble the complexity of real life.

DEM study on the interaction between wet cohesive granular materials and tools

NASA Astrophysics Data System (ADS)

Tsuji, Takuya; Matsui, Yu; Nakagawa, Yuta; Kadono, Yuuichi; Tanaka, Toshitsugu

2013-06-01

A model based on discrete element method has been developed for the interaction between wet cohesive granular materials and mechanical tools with complex geometry. To obtain realistic results, the motion of 52.5 million particles has been simulated and the formation of multiple shear bands during an excavation process by a bulldozer blade was observed.

Multisensory processing of naturalistic objects in motion: a high-density electrical mapping and source estimation study.

PubMed

Senkowski, Daniel; Saint-Amour, Dave; Kelly, Simon P; Foxe, John J

2007-07-01

In everyday life, we continuously and effortlessly integrate the multiple sensory inputs from objects in motion. For instance, the sound and the visual percept of vehicles in traffic provide us with complementary information about the location and motion of vehicles. Here, we used high-density electrical mapping and local auto-regressive average (LAURA) source estimation to study the integration of multisensory objects in motion as reflected in event-related potentials (ERPs). A randomized stream of naturalistic multisensory-audiovisual (AV), unisensory-auditory (A), and unisensory-visual (V) "splash" clips (i.e., a drop falling and hitting a water surface) was presented among non-naturalistic abstract motion stimuli. The visual clip onset preceded the "splash" onset by 100 ms for multisensory stimuli. For naturalistic objects early multisensory integration effects beginning 120-140 ms after sound onset were observed over posterior scalp, with distributed sources localized to occipital cortex, temporal lobule, insular, and medial frontal gyrus (MFG). These effects, together with longer latency interactions (210-250 and 300-350 ms) found in a widespread network of occipital, temporal, and frontal areas, suggest that naturalistic objects in motion are processed at multiple stages of multisensory integration. The pattern of integration effects differed considerably for non-naturalistic stimuli. Unlike naturalistic objects, no early interactions were found for non-naturalistic objects. The earliest integration effects for non-naturalistic stimuli were observed 210-250 ms after sound onset including large portions of the inferior parietal cortex (IPC). As such, there were clear differences in the cortical networks activated by multisensory motion stimuli as a consequence of the semantic relatedness (or lack thereof) of the constituent sensory elements.

Human detection and motion analysis at security points

NASA Astrophysics Data System (ADS)

Ozer, I. Burak; Lv, Tiehan; Wolf, Wayne H.

2003-08-01

This paper presents a real-time video surveillance system for the recognition of specific human activities. Specifically, the proposed automatic motion analysis is used as an on-line alarm system to detect abnormal situations in a campus environment. A smart multi-camera system developed at Princeton University is extended for use in smart environments in which the camera detects the presence of multiple persons as well as their gestures and their interaction in real-time.

Robust, Flexible Motion Control for the Mars Explorer Rovers

NASA Technical Reports Server (NTRS)

Maimone, Mark; Biesiadecki, Jeffrey

2007-01-01

The Mobility Flight Software, running on computers aboard the Mars Explorer Rover (MER) robotic vehicles Spirit and Opportunity, affords the robustness and flexibility of control to enable safe and effective operation of these vehicles in traversing natural terrain. It can make the vehicles perform specific maneuvers commanded from Earth, and/or can autonomously administer multiple aspects of mobility, including choice of motion, measurement of actual motion, and even selection of targets to be approached. Motion of a vehicle can be commanded by use of multiple layers of control, ranging from motor control at a low level, direct drive operations (e.g., motion along a circular arc, motion along a straight line, or turn in place) at an intermediate level to goal-position driving (that is, driving to a specified location) at a high level. The software can also perform high-level assessment of terrain and selection of safe paths across the terrain: this involves processing of the digital equivalent of a local traversability map generated from images acquired by stereoscopic pairs of cameras aboard the vehicles. Other functions of the software include interacting with the rest of the MER flight software and performing safety checks.

Analysis of multiple instructional techniques on the understanding and retention of select mechanical topics

NASA Astrophysics Data System (ADS)

Fetsco, Sara Elizabeth

There are several topics that introductory physics students typically have difficulty understanding. The purpose of this thesis is to investigate if multiple instructional techniques will help students to better understand and retain the material. The three units analyzed in this study are graphing motion, projectile motion, and conservation of momentum. For each unit students were taught using new or altered instructional methods including online laboratory simulations, inquiry labs, and interactive demonstrations. Additionally, traditional instructional methods such as lecture and problem sets were retained. Effectiveness was measured through pre- and post-tests and student opinion surveys. Results suggest that incorporating multiple instructional techniques into teaching will improve student understanding and retention. Students stated that they learned well from all of the instructional methods used except the online simulations.

Approximation of super-ions for single-file diffusion of multiple ions through narrow pores.

PubMed

Kharkyanen, Valery N; Yesylevskyy, Semen O; Berezetskaya, Natalia M

2010-11-01

The general theory of the single-file multiparticle diffusion in the narrow pores could be greatly simplified in the case of inverted bell-like shape of the single-particle energy profile, which is often observed in biological ion channels. There is a narrow and deep groove in the energy landscape of multiple interacting ions in such profiles, which corresponds to the pre-defined optimal conduction pathway in the configurational space. If such groove exists, the motion of multiple ions can be reduced to the motion of single quasiparticle, called the superion, which moves in one-dimensional effective potential. The concept of the superions dramatically reduces the computational complexity of the problem and provides very clear physical interpretation of conduction phenomena in the narrow pores.

Enhancing a slow and weak optomechanical nonlinearity with delayed quantum feedback

PubMed Central

Wang, Zhaoyou; Safavi-Naeini, Amir H.

2017-01-01

A central goal of quantum optics is to generate large interactions between single photons so that one photon can strongly modify the state of another one. In cavity optomechanics, photons interact with the motional degrees of freedom of an optical resonator, for example, by imparting radiation pressure forces on a movable mirror or sensing minute fluctuations in the position of the mirror. Here, we show that the optical nonlinearity arising from these effects, typically too small to operate on single photons, can be sufficiently enhanced with feedback to generate large interactions between single photons. We propose a protocol that allows photons propagating in a waveguide to interact with each other through multiple bounces off an optomechanical system. The protocol is analysed by evolving the full many-body quantum state of the waveguide-coupled system, illustrating that large photon–photon interactions mediated by mechanical motion may be within experimental reach. PMID:28677674

Enhancing a slow and weak optomechanical nonlinearity with delayed quantum feedback

NASA Astrophysics Data System (ADS)

Wang, Zhaoyou; Safavi-Naeini, Amir H.

2017-07-01

A central goal of quantum optics is to generate large interactions between single photons so that one photon can strongly modify the state of another one. In cavity optomechanics, photons interact with the motional degrees of freedom of an optical resonator, for example, by imparting radiation pressure forces on a movable mirror or sensing minute fluctuations in the position of the mirror. Here, we show that the optical nonlinearity arising from these effects, typically too small to operate on single photons, can be sufficiently enhanced with feedback to generate large interactions between single photons. We propose a protocol that allows photons propagating in a waveguide to interact with each other through multiple bounces off an optomechanical system. The protocol is analysed by evolving the full many-body quantum state of the waveguide-coupled system, illustrating that large photon-photon interactions mediated by mechanical motion may be within experimental reach.

Model for the computation of self-motion in biological systems

NASA Technical Reports Server (NTRS)

Perrone, John A.

1992-01-01

A technique is presented by which direction- and speed-tuned cells, such as those commonly found in the middle temporal region of the primate brain, can be utilized to analyze the patterns of retinal image motion that are generated during observer movement through the environment. The developed model determines heading by finding the peak response in a population of detectors or neurons each tuned to a particular heading direction. It is suggested that a complex interaction of multiple cell networks is required for the solution of the self-motion problem in the primate brain.

Field driven magnetic racetrack memory accompanied with the interfacial Dzyaloshinskii-Moriya interaction

NASA Astrophysics Data System (ADS)

Kim, June-Seo; Lee, Hyeon-Jun; Hong, Jung-Il; You, Chun-Yeol

2018-06-01

The in-plane magnetic field pulse driven domain wall motion on a perpendicularly magnetized nanowire is numerically investigated by performing micromagnetic simulations and magnetic domain wall dynamics are evaluated analytically with one-dimensional collective coordinate models including the interfacial Dzyaloshinskii-Moriya interaction. With the action of the precession torque, the chirality and the magnetic field direction dependent displacements of the magnetic domain walls are clearly observed. In order to move Bloch type and Neel type domain walls, a longitudinal and a transverse in-plane magnetic field pulse are required, respectively. The domain wall type (Bloch or Neel) can easily be determined by the dynamic motion of the domain walls under the applied pulse fields. By applying a temporally asymmetric in-plane field pulse and successive notches in the perpendicularly magnetized nanowire strip line with a proper interval, the concept of racetrack memory based on the synchronous displacements of the chirality dependent multiple domain walls is verified to be feasible. Requirement of multiple domain walls with homogeneous chirality is achieved with the help of Dzyaloshinskii-Moriya interaction.

Diffusion of multiple species with excluded-volume effects.

PubMed

Bruna, Maria; Chapman, S Jonathan

2012-11-28

Stochastic models of diffusion with excluded-volume effects are used to model many biological and physical systems at a discrete level. The average properties of the population may be described by a continuum model based on partial differential equations. In this paper we consider multiple interacting subpopulations/species and study how the inter-species competition emerges at the population level. Each individual is described as a finite-size hard core interacting particle undergoing brownian motion. The link between the discrete stochastic equations of motion and the continuum model is considered systematically using the method of matched asymptotic expansions. The system for two species leads to a nonlinear cross-diffusion system for each subpopulation, which captures the enhancement of the effective diffusion rate due to excluded-volume interactions between particles of the same species, and the diminishment due to particles of the other species. This model can explain two alternative notions of the diffusion coefficient that are often confounded, namely collective diffusion and self-diffusion. Simulations of the discrete system show good agreement with the analytic results.

The forward rainbow scattering of low energy protons by a graphene sheet

NASA Astrophysics Data System (ADS)

Ćosić, M.; Petrović, S.; Nešković, N.

2018-05-01

This article studies the rainbow scattering of 5-keV protons by the single sheet of free-standing graphene and its possible use as a tool for investigation of the ion-graphene interaction. The proton-graphene interaction potential was constructed by using the Doyle-Turner, ZBL, and Molière proton-carbon interaction potentials. The thermal motion of carbon atoms was included by averaging the potentials according to the Debye model. Proton trajectories were obtained by numerical solution of the corresponding Newton equations of motion. They were used to obtain the mapping of the proton initial positions to their scattering angles. Morphological properties of the introduced mapping including its multiplicity and the rainbow singularities were used to explain important features of the obtained angular distributions of transmitted protons.

Patterns of fMRI activity dissociate overlapping functional brain areas that respond to biological motion.

PubMed

Peelen, Marius V; Wiggett, Alison J; Downing, Paul E

2006-03-16

Accurate perception of the actions and intentions of other people is essential for successful interactions in a social environment. Several cortical areas that support this process respond selectively in fMRI to static and dynamic displays of human bodies and faces. Here we apply pattern-analysis techniques to arrive at a new understanding of the neural response to biological motion. Functionally defined body-, face-, and motion-selective visual areas all responded significantly to "point-light" human motion. Strikingly, however, only body selectivity was correlated, on a voxel-by-voxel basis, with biological motion selectivity. We conclude that (1) biological motion, through the process of structure-from-motion, engages areas involved in the analysis of the static human form; (2) body-selective regions in posterior fusiform gyrus and posterior inferior temporal sulcus overlap with, but are distinct from, face- and motion-selective regions; (3) the interpretation of region-of-interest findings may be substantially altered when multiple patterns of selectivity are considered.

Body motion and physics: How elementary school students use gesture and action to make sense of the physical world

NASA Astrophysics Data System (ADS)

Noble, Tracy

This study is an exploration of the role of physical activity in making sense of the physical world. Recent work on embodied cognition has helped to break down the barrier between the body and cognition, providing the inspiration for this work. In this study, I asked ten elementary-school students to explain to me how a toy parachute works. The methods used were adapted from those used to study the role of the body in cognition in science education, child development, and psychology. This study focused on the processes of learning rather than on measuring learning outcomes. Multiple levels of analysis were pursued in a mixed-method research design. The first level was individual analyses of two students' utterances and body motions. These analyses provided initial hypotheses about the interaction of speech and body motion in students' developing understandings. The second level was group analyses of all ten students' data, in search of patterns and relationships between body motion and speech production across all the student-participants. Finally, a third level of analysis was used to explore all cases in which students produced analogies while they discussed how the parachute works. The multiple levels of analysis used in this study allowed for raising and answering some questions, and allowed for the characterization of both individual differences and group commonalities. The findings of this study show that there are several significant patterns of interaction between body motion and speech that demonstrate a role for the body in cognition. The use of sensory feedback from physical interactions with objects to create new explanations, and the use of interactions with objects to create blended spaces to support the construction of analogies are two of these patterns. Future work is needed to determine the generalizability of these patterns to other individuals and other learning contexts. However, the existence of these patterns lends concrete support to the ideas of embodied cognition and demonstrates how students can use their own embodied experience to understand the world.

Systems of Multiple Planets

NASA Astrophysics Data System (ADS)

Marcy, G. W.; Fischer, D. A.; Butler, R. P.; Vogt, S. S.

To date, 10 stars are known which harbor two or three planets. These systems reveal secular and mean motion resonances in some systems and consist of widely separated, eccentric orbits in others. Both of the triple planet systems, namely Upsilon And and 55 Cancri, exhibit evidence of resonances. The two planets orbiting GJ 876 exhibit both mean-motion and secular resonances and they perturb each other so strongly that the evolution of the orbits is revealed in the Doppler measurements. The common occurrence of resonances suggests that delicate dynamical processes often shape the architecture of planetary systems. Likely processes include planet migration in a viscous disk, eccentricity pumping by the planet-disk interaction, and resonance capture of two planets. We find a class of "hierarchical" double-planet systems characterized by two planets in widely separated orbits, defined to have orbital period ratios greater than 5 to 1. In such systems, resonant interactions are weak, leaving high-order interactions and Kozai resonances plausibly important. We compare the planets that are single with those in multiple systems. We find that neither the two mass distributions nor the two eccentricity distributions are significantly different. This similarity in single and multiple systems suggests that similar dynamical processes may operate in both. The origin of eccentricities may stem from a multi-planet past or from interactions between planets and disk. Multiple planets in resonances can pump their eccentricities pumping resulting in one planet being ejected from the system or sent into the star, leaving a (more massive) single planet in an eccentric orbit. The distribution of semimajor axes of all known extrasolar planets shows a rise toward larger orbits, portending a population of gas-giant planets that reside beyond 3 AU, arguably in less perturbed, more circular orbits.

Automatic acquisition of motion trajectories: tracking hockey players

NASA Astrophysics Data System (ADS)

Okuma, Kenji; Little, James J.; Lowe, David

2003-12-01

Computer systems that have the capability of analyzing complex and dynamic scenes play an essential role in video annotation. Scenes can be complex in such a way that there are many cluttered objects with different colors, shapes and sizes, and can be dynamic with multiple interacting moving objects and a constantly changing background. In reality, there are many scenes that are complex, dynamic, and challenging enough for computers to describe. These scenes include games of sports, air traffic, car traffic, street intersections, and cloud transformations. Our research is about the challenge of inventing a descriptive computer system that analyzes scenes of hockey games where multiple moving players interact with each other on a constantly moving background due to camera motions. Ultimately, such a computer system should be able to acquire reliable data by extracting the players" motion as their trajectories, querying them by analyzing the descriptive information of data, and predict the motions of some hockey players based on the result of the query. Among these three major aspects of the system, we primarily focus on visual information of the scenes, that is, how to automatically acquire motion trajectories of hockey players from video. More accurately, we automatically analyze the hockey scenes by estimating parameters (i.e., pan, tilt, and zoom) of the broadcast cameras, tracking hockey players in those scenes, and constructing a visual description of the data by displaying trajectories of those players. Many technical problems in vision such as fast and unpredictable players' motions and rapid camera motions make our challenge worth tackling. To the best of our knowledge, there have not been any automatic video annotation systems for hockey developed in the past. Although there are many obstacles to overcome, our efforts and accomplishments would hopefully establish the infrastructure of the automatic hockey annotation system and become a milestone for research in automatic video annotation in this domain.

Acoustoelasticity. [sound-structure interaction

NASA Technical Reports Server (NTRS)

Dowell, E. H.

1977-01-01

Sound or pressure variations inside bounded enclosures are investigated. Mathematical models are given for determining: (1) the interaction between the sound pressure field and the flexible wall of a Helmholtz resonator; (2) coupled fluid-structural motion of an acoustic cavity with a flexible and/or absorbing wall; (3) acoustic natural modes in multiple connected cavities; and (4) the forced response of a cavity with a flexible and/or absorbing wall. Numerical results are discussed.

Development of a body motion interactive system with a weight voting mechanism and computer vision technology

NASA Astrophysics Data System (ADS)

Lin, Chern-Sheng; Chen, Chia-Tse; Shei, Hung-Jung; Lay, Yun-Long; Chiu, Chuang-Chien

2012-09-01

This study develops a body motion interactive system with computer vision technology. This application combines interactive games, art performing, and exercise training system. Multiple image processing and computer vision technologies are used in this study. The system can calculate the characteristics of an object color, and then perform color segmentation. When there is a wrong action judgment, the system will avoid the error with a weight voting mechanism, which can set the condition score and weight value for the action judgment, and choose the best action judgment from the weight voting mechanism. Finally, this study estimated the reliability of the system in order to make improvements. The results showed that, this method has good effect on accuracy and stability during operations of the human-machine interface of the sports training system.

Optimized "detectors" for dynamics analysis in solid-state NMR

NASA Astrophysics Data System (ADS)

Smith, Albert A.; Ernst, Matthias; Meier, Beat H.

2018-01-01

Relaxation in nuclear magnetic resonance (NMR) results from stochastic motions that modulate anisotropic NMR interactions. Therefore, measurement of relaxation-rate constants can be used to characterize molecular-dynamic processes. The motion is often characterized by Markov processes using an auto-correlation function, which is assumed to be a sum of multiple decaying exponentials. We have recently shown that such a model can lead to severe misrepresentation of the real motion, when the real correlation function is more complex than the model. Furthermore, multiple distributions of motion may yield the same set of dynamics data. Therefore, we introduce optimized dynamics "detectors" to characterize motions which are linear combinations of relaxation-rate constants. A detector estimates the average or total amplitude of motion for a range of motional correlation times. The information obtained through the detectors is less specific than information obtained using an explicit model, but this is necessary because the information contained in the relaxation data is ambiguous, if one does not know the correct motional model. On the other hand, if one has a molecular dynamics trajectory, one may calculate the corresponding detector responses, allowing direct comparison to experimental NMR dynamics analysis. We describe how to construct a set of optimized detectors for a given set of relaxation measurements. We then investigate the properties of detectors for a number of different data sets, thus gaining an insight into the actual information content of the NMR data. Finally, we show an example analysis of ubiquitin dynamics data using detectors, using the DIFRATE software.

Exploring direct 3D interaction for full horizontal parallax light field displays using leap motion controller.

PubMed

Adhikarla, Vamsi Kiran; Sodnik, Jaka; Szolgay, Peter; Jakus, Grega

2015-04-14

This paper reports on the design and evaluation of direct 3D gesture interaction with a full horizontal parallax light field display. A light field display defines a visual scene using directional light beams emitted from multiple light sources as if they are emitted from scene points. Each scene point is rendered individually resulting in more realistic and accurate 3D visualization compared to other 3D displaying technologies. We propose an interaction setup combining the visualization of objects within the Field Of View (FOV) of a light field display and their selection through freehand gesture tracked by the Leap Motion Controller. The accuracy and usefulness of the proposed interaction setup was also evaluated in a user study with test subjects. The results of the study revealed high user preference for free hand interaction with light field display as well as relatively low cognitive demand of this technique. Further, our results also revealed some limitations and adjustments of the proposed setup to be addressed in future work.

Adaptive walking of a quadrupedal robot based on layered biological reflexes

NASA Astrophysics Data System (ADS)

Zhang, Xiuli; Mingcheng, E.; Zeng, Xiangyu; Zheng, Haojun

2012-07-01

A multiple-legged robot is traditionally controlled by using its dynamic model. But the dynamic-model-based approach fails to acquire satisfactory performances when the robot faces rough terrains and unknown environments. Referring animals' neural control mechanisms, a control model is built for a quadruped robot walking adaptively. The basic rhythmic motion of the robot is controlled by a well-designed rhythmic motion controller(RMC) comprising a central pattern generator(CPG) for hip joints and a rhythmic coupler (RC) for knee joints. CPG and RC have relationships of motion-mapping and rhythmic couple. Multiple sensory-motor models, abstracted from the neural reflexes of a cat, are employed. These reflex models are organized and thus interact with the CPG in three layers, to meet different requirements of complexity and response time to the tasks. On the basis of the RMC and layered biological reflexes, a quadruped robot is constructed, which can clear obstacles and walk uphill and downhill autonomously, and make a turn voluntarily in uncertain environments, interacting with the environment in a way similar to that of an animal. The paper provides a biologically inspired architecture, with which a robot can walk adaptively in uncertain environments in a simple and effective way, and achieve better performances.

Traffic and Driving Simulator Based on Architecture of Interactive Motion.

PubMed

Paz, Alexander; Veeramisti, Naveen; Khaddar, Romesh; de la Fuente-Mella, Hanns; Modorcea, Luiza

2015-01-01

This study proposes an architecture for an interactive motion-based traffic simulation environment. In order to enhance modeling realism involving actual human beings, the proposed architecture integrates multiple types of simulation, including: (i) motion-based driving simulation, (ii) pedestrian simulation, (iii) motorcycling and bicycling simulation, and (iv) traffic flow simulation. The architecture has been designed to enable the simulation of the entire network; as a result, the actual driver, pedestrian, and bike rider can navigate anywhere in the system. In addition, the background traffic interacts with the actual human beings. This is accomplished by using a hybrid mesomicroscopic traffic flow simulation modeling approach. The mesoscopic traffic flow simulation model loads the results of a user equilibrium traffic assignment solution and propagates the corresponding traffic through the entire system. The microscopic traffic flow simulation model provides background traffic around the vicinities where actual human beings are navigating the system. The two traffic flow simulation models interact continuously to update system conditions based on the interactions between actual humans and the fully simulated entities. Implementation efforts are currently in progress and some preliminary tests of individual components have been conducted. The implementation of the proposed architecture faces significant challenges ranging from multiplatform and multilanguage integration to multievent communication and coordination.

Traffic and Driving Simulator Based on Architecture of Interactive Motion

PubMed Central

Paz, Alexander; Veeramisti, Naveen; Khaddar, Romesh; de la Fuente-Mella, Hanns; Modorcea, Luiza

2015-01-01

This study proposes an architecture for an interactive motion-based traffic simulation environment. In order to enhance modeling realism involving actual human beings, the proposed architecture integrates multiple types of simulation, including: (i) motion-based driving simulation, (ii) pedestrian simulation, (iii) motorcycling and bicycling simulation, and (iv) traffic flow simulation. The architecture has been designed to enable the simulation of the entire network; as a result, the actual driver, pedestrian, and bike rider can navigate anywhere in the system. In addition, the background traffic interacts with the actual human beings. This is accomplished by using a hybrid mesomicroscopic traffic flow simulation modeling approach. The mesoscopic traffic flow simulation model loads the results of a user equilibrium traffic assignment solution and propagates the corresponding traffic through the entire system. The microscopic traffic flow simulation model provides background traffic around the vicinities where actual human beings are navigating the system. The two traffic flow simulation models interact continuously to update system conditions based on the interactions between actual humans and the fully simulated entities. Implementation efforts are currently in progress and some preliminary tests of individual components have been conducted. The implementation of the proposed architecture faces significant challenges ranging from multiplatform and multilanguage integration to multievent communication and coordination. PMID:26491711

Shader Lamps Virtual Patients: the physical manifestation of virtual patients.

PubMed

Rivera-Gutierrez, Diego; Welch, Greg; Lincoln, Peter; Whitton, Mary; Cendan, Juan; Chesnutt, David A; Fuchs, Henry; Lok, Benjamin

2012-01-01

We introduce the notion of Shader Lamps Virtual Patients (SLVP) - the combination of projector-based Shader Lamps Avatars and interactive virtual humans. This paradigm uses Shader Lamps Avatars technology to give a 3D physical presence to conversational virtual humans, improving their social interactivity and enabling them to share the physical space with the user. The paradigm scales naturally to multiple viewers, allowing for scenarios where an instructor and multiple students are involved in the training. We have developed a physical-virtual patient for medical students to conduct ophthalmic exams, in an interactive training experience. In this experience, the trainee practices multiple skills simultaneously, including using a surrogate optical instrument in front of a physical head, conversing with the patient about his fears, observing realistic head motion, and practicing patient safety. Here we present a prototype system and results from a preliminary formative evaluation of the system.

Computational design of microscopic swimmers and capsules: From directed motion to collective behavior

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

Nikolov, Svetoslav V.; Shum, Henry; Balazs, Anna C.

Systems of motile microscopic particles can exhibit behaviors that resemble those of living microorganisms, including cooperative motion, self-organization, and adaptability to changing environments. Using mesoscale computational modeling, we design synthetic microswimmers and microcapsules that undergo controllable, self-propelled motion in solution. Stimuli-responsive hydrogels are used to actuate the microswimmers and to enable their navigation and chemotaxing behavior. The self-propelled motion of microcapsules on solid surfaces is achieved by the release of encapsulated solutes that alter the surface adhesiveness. These signaling solutes also enable interactions among multiple microcapsules that lead to complex, cooperative behavior. Our findings provide guidelines for creating microscopic devicesmore » and machines able to autonomously move and mimic the communication and chemotaxis of biological microorganisms.« less

Flow visualization and modeling for education and outreach in low-income countries

NASA Astrophysics Data System (ADS)

Motanated, K.

2016-12-01

Being able to visualize the dynamic interaction between the movement of water and sediment flux is undeniably a profound tool for students and novices to understand complicated earth surface processes. In a laser-sheet flow visualization technique, a light source that is thin and monochromatic is required to illuminate sediments or tracers in the flow. However, an ideal laser sheet generator is rather expensive, especially for schools and universities residing in low-income countries. This project is proposing less-expensive options for a laser-sheet source and flow visualization experiment configuration for qualitative observation and quantitative analysis of the interaction between fluid media and sediments. Here, Fresnel lens is used to convert from point laser into sheet laser. Multiple combinations of laser diodes of various wavelength (nanometer) and power (milliwatt) and Fresnel lenses of various dimensions are analyzed. The pair that is able to produce the thinnest and brightest light sheet is not only effective but also affordable. The motion of sediments in a flow can be observed by illuminating the laser-sheet in an interested flow region. The particle motion is recorded by a video camera that is capable of taking multiple frames per second and having a narrow depth of view. The recorded video file can be played in a slow-motion mode so students can visually observe and qualitatively analyze the particle motion. An open source software package for Particle Imaging Velocimetry (PIV) can calculate the local velocity of particles from still images extracted from the video and create a vector map depicting particle motion. This flow visualization experiment is inexpensive and the configuration is simple to setup. Most importantly, this flow visualization technique serves as a fundamental tool for earth surface process education and can further be applied to sedimentary process modeling.

Modelling vortex-induced fluid-structure interaction.

PubMed

Benaroya, Haym; Gabbai, Rene D

2008-04-13

The principal goal of this research is developing physics-based, reduced-order, analytical models of nonlinear fluid-structure interactions associated with offshore structures. Our primary focus is to generalize the Hamilton's variational framework so that systems of flow-oscillator equations can be derived from first principles. This is an extension of earlier work that led to a single energy equation describing the fluid-structure interaction. It is demonstrated here that flow-oscillator models are a subclass of the general, physical-based framework. A flow-oscillator model is a reduced-order mechanical model, generally comprising two mechanical oscillators, one modelling the structural oscillation and the other a nonlinear oscillator representing the fluid behaviour coupled to the structural motion.Reduced-order analytical model development continues to be carried out using a Hamilton's principle-based variational approach. This provides flexibility in the long run for generalizing the modelling paradigm to complex, three-dimensional problems with multiple degrees of freedom, although such extension is very difficult. As both experimental and analytical capabilities advance, the critical research path to developing and implementing fluid-structure interaction models entails-formulating generalized equations of motion, as a superset of the flow-oscillator models; and-developing experimentally derived, semi-analytical functions to describe key terms in the governing equations of motion. The developed variational approach yields a system of governing equations. This will allow modelling of multiple d.f. systems. The extensions derived generalize the Hamilton's variational formulation for such problems. The Navier-Stokes equations are derived and coupled to the structural oscillator. This general model has been shown to be a superset of the flow-oscillator model. Based on different assumptions, one can derive a variety of flow-oscillator models.

Yang Monopoles and Emergent Three-Dimensional Topological Defects in Interacting Bosons

NASA Astrophysics Data System (ADS)

Yan, Yangqian; Zhou, Qi

2018-06-01

The Yang monopole as a zero-dimensional topological defect has been well established in multiple fields in physics. However, it remains an intriguing question to understand the interaction effects on Yang monopoles. Here, we show that the collective motion of many interacting bosons gives rise to exotic topological defects that are distinct from Yang monopoles seen by a single particle. Whereas interactions may distribute Yang monopoles in the parameter space or glue them to a single giant one of multiple charges, three-dimensional topological defects also arise from continuous manifolds of degenerate many-body eigenstates. Their projections in lower dimensions lead to knotted nodal lines and nodal rings. Our results suggest that ultracold bosonic atoms can be used to create emergent topological defects and directly measure topological invariants that are not easy to access in solids.

Bilinear modeling of EMG signals to extract user-independent features for multiuser myoelectric interface.

PubMed

Matsubara, Takamitsu; Morimoto, Jun

2013-08-01

In this study, we propose a multiuser myoelectric interface that can easily adapt to novel users. When a user performs different motions (e.g., grasping and pinching), different electromyography (EMG) signals are measured. When different users perform the same motion (e.g., grasping), different EMG signals are also measured. Therefore, designing a myoelectric interface that can be used by multiple users to perform multiple motions is difficult. To cope with this problem, we propose for EMG signals a bilinear model that is composed of two linear factors: 1) user dependent and 2) motion dependent. By decomposing the EMG signals into these two factors, the extracted motion-dependent factors can be used as user-independent features. We can construct a motion classifier on the extracted feature space to develop the multiuser interface. For novel users, the proposed adaptation method estimates the user-dependent factor through only a few interactions. The bilinear EMG model with the estimated user-dependent factor can extract the user-independent features from the novel user data. We applied our proposed method to a recognition task of five hand gestures for robotic hand control using four-channel EMG signals measured from subject forearms. Our method resulted in 73% accuracy, which was statistically significantly different from the accuracy of standard nonmultiuser interfaces, as the result of a two-sample t -test at a significance level of 1%.

FuryExplorer: visual-interactive exploration of horse motion capture data

NASA Astrophysics Data System (ADS)

Wilhelm, Nils; Vögele, Anna; Zsoldos, Rebeka; Licka, Theresia; Krüger, Björn; Bernard, Jürgen

2015-01-01

The analysis of equine motion has a long tradition in the past of mankind. Equine biomechanics aims at detecting characteristics of horses indicative of good performance. Especially, veterinary medicine gait analysis plays an important role in diagnostics and in the emerging research of long-term effects of athletic exercises. More recently, the incorporation of motion capture technology contributed to an easier and faster analysis, with a trend from mere observation of horses towards the analysis of multivariate time-oriented data. However, due to the novelty of this topic being raised within an interdisciplinary context, there is yet a lack of visual-interactive interfaces to facilitate time series data analysis and information discourse for the veterinary and biomechanics communities. In this design study, we bring visual analytics technology into the respective domains, which, to our best knowledge, was never approached before. Based on requirements developed in the domain characterization phase, we present a visual-interactive system for the exploration of horse motion data. The system provides multiple views which enable domain experts to explore frequent poses and motions, but also to drill down to interesting subsets, possibly containing unexpected patterns. We show the applicability of the system in two exploratory use cases, one on the comparison of different gait motions, and one on the analysis of lameness recovery. Finally, we present the results of a summative user study conducted in the environment of the domain experts. The overall outcome was a significant improvement in effectiveness and efficiency in the analytical workflow of the domain experts.

Computer-assisted time-averaged holograms of the motion of the surface of the mammalian tympanic membrane with sound stimuli of 0.4 to 25 kHz

PubMed Central

Rosowski, John J.; Cheng, Jeffrey Tao; Ravicz, Michael E.; Hulli, Nesim; Hernandez-Montes, Maria; Harrington, Ellery; Furlong, Cosme

2009-01-01

Time-averaged holograms describing the sound-induced motion of the tympanic membrane (TM) in cadaveric preparations from three mammalian species and one live ear were measured using opto-electronic holography. This technique allows rapid measurements of the magnitude of motion of the tympanic membrane surface at frequencies as high as 25 kHz. The holograms measured in response to low and middle-frequency sound stimuli are similar to previously reported time-averaged holograms. However, at higher frequencies (f > 4 kHz), our holograms reveal unique TM surface displacement patterns that consist of highly-ordered arrangements of multiple local displacement magnitude maxima, each of which is surrounded by nodal areas of low displacement magnitude. These patterns are similar to modal patterns (two-dimensional standing waves) produced by either the interaction of surface waves traveling in multiple directions or the uniform stimulation of modes of motion that are determined by the structural properties and boundary conditions of the TM. From the ratio of the displacement magnitude peaks to nodal valleys in these apparent surface waves, we estimate a Standing Wave Ratio of at least 4 that is consistent with energy reflection coefficients at the TM boundaries of at least 0.35. It is also consistent with small losses within the uniformly stimulated modal surface waves. We also estimate possible TM surface wave speeds that vary with frequency and species from 20 to 65 m/s, consistent with other estimates in the literature. The presence of standing wave or modal phenomena has previously been intuited from measurements of TM function, but is ignored in some models of tympanic membrane function. Whether these standing waves result either from the interactions of multiple surface waves that travel along the membrane, or by uniformly excited modal displacement patterns of the entire TM surface is still to be determined. PMID:19328841

Computer-assisted time-averaged holograms of the motion of the surface of the mammalian tympanic membrane with sound stimuli of 0.4-25 kHz.

PubMed

Rosowski, John J; Cheng, Jeffrey Tao; Ravicz, Michael E; Hulli, Nesim; Hernandez-Montes, Maria; Harrington, Ellery; Furlong, Cosme

2009-07-01

Time-averaged holograms describing the sound-induced motion of the tympanic membrane (TM) in cadaveric preparations from three mammalian species and one live ear were measured using opto-electronic holography. This technique allows rapid measurements of the magnitude of motion of the tympanic membrane surface at frequencies as high as 25 kHz. The holograms measured in response to low and middle-frequency sound stimuli are similar to previously reported time-averaged holograms. However, at higher frequencies (f>4 kHz), our holograms reveal unique TM surface displacement patterns that consist of highly-ordered arrangements of multiple local displacement magnitude maxima, each of which is surrounded by nodal areas of low displacement magnitude. These patterns are similar to modal patterns (two-dimensional standing waves) produced by either the interaction of surface waves traveling in multiple directions or the uniform stimulation of modes of motion that are determined by the structural properties and boundary conditions of the TM. From the ratio of the displacement magnitude peaks to nodal valleys in these apparent surface waves, we estimate a Standing Wave Ratio of at least 4 that is consistent with energy reflection coefficients at the TM boundaries of at least 0.35. It is also consistent with small losses within the uniformly stimulated modal surface waves. We also estimate possible TM surface wave speeds that vary with frequency and species from 20 to 65 m/s, consistent with other estimates in the literature. The presence of standing wave or modal phenomena has previously been intuited from measurements of TM function, but is ignored in some models of tympanic membrane function. Whether these standing waves result either from the interactions of multiple surface waves that travel along the membrane, or by uniformly excited modal displacement patterns of the entire TM surface is still to be determined.

Ubiquitous human upper-limb motion estimation using wearable sensors.

PubMed

Zhang, Zhi-Qiang; Wong, Wai-Choong; Wu, Jian-Kang

2011-07-01

Human motion capture technologies have been widely used in a wide spectrum of applications, including interactive game and learning, animation, film special effects, health care, navigation, and so on. The existing human motion capture techniques, which use structured multiple high-resolution cameras in a dedicated studio, are complicated and expensive. With the rapid development of microsensors-on-chip, human motion capture using wearable microsensors has become an active research topic. Because of the agility in movement, upper-limb motion estimation has been regarded as the most difficult problem in human motion capture. In this paper, we take the upper limb as our research subject and propose a novel ubiquitous upper-limb motion estimation algorithm, which concentrates on modeling the relationship between upper-arm movement and forearm movement. A link structure with 5 degrees of freedom (DOF) is proposed to model the human upper-limb skeleton structure. Parameters are defined according to Denavit-Hartenberg convention, forward kinematics equations are derived, and an unscented Kalman filter is deployed to estimate the defined parameters. The experimental results have shown that the proposed upper-limb motion capture and analysis algorithm outperforms other fusion methods and provides accurate results in comparison to the BTS optical motion tracker.

Exploring Direct 3D Interaction for Full Horizontal Parallax Light Field Displays Using Leap Motion Controller

PubMed Central

Adhikarla, Vamsi Kiran; Sodnik, Jaka; Szolgay, Peter; Jakus, Grega

2015-01-01

This paper reports on the design and evaluation of direct 3D gesture interaction with a full horizontal parallax light field display. A light field display defines a visual scene using directional light beams emitted from multiple light sources as if they are emitted from scene points. Each scene point is rendered individually resulting in more realistic and accurate 3D visualization compared to other 3D displaying technologies. We propose an interaction setup combining the visualization of objects within the Field Of View (FOV) of a light field display and their selection through freehand gesture tracked by the Leap Motion Controller. The accuracy and usefulness of the proposed interaction setup was also evaluated in a user study with test subjects. The results of the study revealed high user preference for free hand interaction with light field display as well as relatively low cognitive demand of this technique. Further, our results also revealed some limitations and adjustments of the proposed setup to be addressed in future work. PMID:25875189

Fluid-driven origami-inspired artificial muscles.

PubMed

Li, Shuguang; Vogt, Daniel M; Rus, Daniela; Wood, Robert J

2017-12-12

Artificial muscles hold promise for safe and powerful actuation for myriad common machines and robots. However, the design, fabrication, and implementation of artificial muscles are often limited by their material costs, operating principle, scalability, and single-degree-of-freedom contractile actuation motions. Here we propose an architecture for fluid-driven origami-inspired artificial muscles. This concept requires only a compressible skeleton, a flexible skin, and a fluid medium. A mechanical model is developed to explain the interaction of the three components. A fabrication method is introduced to rapidly manufacture low-cost artificial muscles using various materials and at multiple scales. The artificial muscles can be programed to achieve multiaxial motions including contraction, bending, and torsion. These motions can be aggregated into systems with multiple degrees of freedom, which are able to produce controllable motions at different rates. Our artificial muscles can be driven by fluids at negative pressures (relative to ambient). This feature makes actuation safer than most other fluidic artificial muscles that operate with positive pressures. Experiments reveal that these muscles can contract over 90% of their initial lengths, generate stresses of ∼600 kPa, and produce peak power densities over 2 kW/kg-all equal to, or in excess of, natural muscle. This architecture for artificial muscles opens the door to rapid design and low-cost fabrication of actuation systems for numerous applications at multiple scales, ranging from miniature medical devices to wearable robotic exoskeletons to large deployable structures for space exploration. Copyright © 2017 the Author(s). Published by PNAS.

Fluid-driven origami-inspired artificial muscles

PubMed Central

Li, Shuguang; Vogt, Daniel M.; Rus, Daniela; Wood, Robert J.

2017-01-01

Artificial muscles hold promise for safe and powerful actuation for myriad common machines and robots. However, the design, fabrication, and implementation of artificial muscles are often limited by their material costs, operating principle, scalability, and single-degree-of-freedom contractile actuation motions. Here we propose an architecture for fluid-driven origami-inspired artificial muscles. This concept requires only a compressible skeleton, a flexible skin, and a fluid medium. A mechanical model is developed to explain the interaction of the three components. A fabrication method is introduced to rapidly manufacture low-cost artificial muscles using various materials and at multiple scales. The artificial muscles can be programed to achieve multiaxial motions including contraction, bending, and torsion. These motions can be aggregated into systems with multiple degrees of freedom, which are able to produce controllable motions at different rates. Our artificial muscles can be driven by fluids at negative pressures (relative to ambient). This feature makes actuation safer than most other fluidic artificial muscles that operate with positive pressures. Experiments reveal that these muscles can contract over 90% of their initial lengths, generate stresses of ∼600 kPa, and produce peak power densities over 2 kW/kg—all equal to, or in excess of, natural muscle. This architecture for artificial muscles opens the door to rapid design and low-cost fabrication of actuation systems for numerous applications at multiple scales, ranging from miniature medical devices to wearable robotic exoskeletons to large deployable structures for space exploration. PMID:29180416

Fluid-driven origami-inspired artificial muscles

NASA Astrophysics Data System (ADS)

Li, Shuguang; Vogt, Daniel M.; Rus, Daniela; Wood, Robert J.

2017-12-01

Artificial muscles hold promise for safe and powerful actuation for myriad common machines and robots. However, the design, fabrication, and implementation of artificial muscles are often limited by their material costs, operating principle, scalability, and single-degree-of-freedom contractile actuation motions. Here we propose an architecture for fluid-driven origami-inspired artificial muscles. This concept requires only a compressible skeleton, a flexible skin, and a fluid medium. A mechanical model is developed to explain the interaction of the three components. A fabrication method is introduced to rapidly manufacture low-cost artificial muscles using various materials and at multiple scales. The artificial muscles can be programed to achieve multiaxial motions including contraction, bending, and torsion. These motions can be aggregated into systems with multiple degrees of freedom, which are able to produce controllable motions at different rates. Our artificial muscles can be driven by fluids at negative pressures (relative to ambient). This feature makes actuation safer than most other fluidic artificial muscles that operate with positive pressures. Experiments reveal that these muscles can contract over 90% of their initial lengths, generate stresses of ˜600 kPa, and produce peak power densities over 2 kW/kg—all equal to, or in excess of, natural muscle. This architecture for artificial muscles opens the door to rapid design and low-cost fabrication of actuation systems for numerous applications at multiple scales, ranging from miniature medical devices to wearable robotic exoskeletons to large deployable structures for space exploration.

Inchworm movement of two rings switching onto a thread by biased Brownian diffusion represent a three-body problem.

PubMed

Benson, Christopher R; Maffeo, Christopher; Fatila, Elisabeth M; Liu, Yun; Sheetz, Edward G; Aksimentiev, Aleksei; Singharoy, Abhishek; Flood, Amar H

2018-05-07

The coordinated motion of many individual components underpins the operation of all machines. However, despite generations of experience in engineering, understanding the motion of three or more coupled components remains a challenge, known since the time of Newton as the "three-body problem." Here, we describe, quantify, and simulate a molecular three-body problem of threading two molecular rings onto a linear molecular thread. Specifically, we use voltage-triggered reduction of a tetrazine-based thread to capture two cyanostar macrocycles and form a [3]pseudorotaxane product. As a consequence of the noncovalent coupling between the cyanostar rings, we find the threading occurs by an unexpected and rare inchworm-like motion where one ring follows the other. The mechanism was derived from controls, analysis of cyclic voltammetry (CV) traces, and Brownian dynamics simulations. CVs from two noncovalently interacting rings match that of two covalently linked rings designed to thread via the inchworm pathway, and they deviate considerably from the CV of a macrocycle designed to thread via a stepwise pathway. Time-dependent electrochemistry provides estimates of rate constants for threading. Experimentally derived parameters (energy wells, barriers, diffusion coefficients) helped determine likely pathways of motion with rate-kinetics and Brownian dynamics simulations. Simulations verified intercomponent coupling could be separated into ring-thread interactions for kinetics, and ring-ring interactions for thermodynamics to reduce the three-body problem to a two-body one. Our findings provide a basis for high-throughput design of molecular machinery with multiple components undergoing coupled motion.

Mapping cardiogenic oscillations using synchrotron-based phase contrast CT imaging

NASA Astrophysics Data System (ADS)

Thurgood, Jordan; Dubsky, Stephen; Siu, Karen K. W.; Wallace, Megan; Siew, Melissa; Hooper, Stuart; Fouras, Andreas

2012-10-01

In many animals, including humans, the lungs encase the majority of the heart thus the motion of each organ affects the other. The effects of the motion of the heart on the lungs potentially provides information with regards to both lung and heart health. We present a novel technique that is capable of measuring the effect of the heart on the surrounding lung tissue through the use of advanced synchrotron imaging techniques and recently developed X-ray velocimetry methods. This technique generates 2D frequency response maps of the lung tissue motion at multiple projection angles from projection X-ray images. These frequency response maps are subsequently used to generate 3D reconstructions of the lung tissue exhibiting motion at the frequency of ventilation and the lung tissue exhibiting motion at the frequency of the heart. This technique has a combined spatial and temporal resolution sufficient to observe the dynamic and complex 3D nature of lung-heart interactions.

Simulation of cooperating robot manipulators on a mobile platform

NASA Technical Reports Server (NTRS)

Murphy, Stephen H.; Wen, John Ting-Yung; Saridis, George N.

1991-01-01

The dynamic equations of motion are presented for two or more cooperating manipulators on a freely moving mobile platform. The system of cooperating robot manipulators forms a closed kinematic chain where the force of interaction must be included in the formulation of robot and platform dynamics. The formulation includes the full dynamic interactions from arms to platform and arm tip to arm tip, and the possible translation and rotation of the platform. The equations of motion are shown to be identical in structure to the fixed-platform cooperative manipulator dynamics. The number of DOFs of the system is sufficiently large to make recursive dynamic calculation methods potentially more efficient than closed-form solutions. A complete simulation with two 6-DOF manipulators of a free-floating platform is presented along a with a multiple-arm controller to position the common load.

Novel method of extracting motion from natural movies.

PubMed

Suzuki, Wataru; Ichinohe, Noritaka; Tani, Toshiki; Hayami, Taku; Miyakawa, Naohisa; Watanabe, Satoshi; Takeichi, Hiroshige

2017-11-01

The visual system in primates can be segregated into motion and shape pathways. Interaction occurs at multiple stages along these pathways. Processing of shape-from-motion and biological motion is considered to be a higher-order integration process involving motion and shape information. However, relatively limited types of stimuli have been used in previous studies on these integration processes. We propose a new algorithm to extract object motion information from natural movies and to move random dots in accordance with the information. The object motion information is extracted by estimating the dynamics of local normal vectors of the image intensity projected onto the x-y plane of the movie. An electrophysiological experiment on two adult common marmoset monkeys (Callithrix jacchus) showed that the natural and random dot movies generated with this new algorithm yielded comparable neural responses in the middle temporal visual area. In principle, this algorithm provided random dot motion stimuli containing shape information for arbitrary natural movies. This new method is expected to expand the neurophysiological and psychophysical experimental protocols to elucidate the integration processing of motion and shape information in biological systems. The novel algorithm proposed here was effective in extracting object motion information from natural movies and provided new motion stimuli to investigate higher-order motion information processing. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Relations between Automatically Extracted Motion Features and the Quality of Mother-Infant Interactions at 4 and 13 Months

PubMed Central

Egmose, Ida; Varni, Giovanna; Cordes, Katharina; Smith-Nielsen, Johanne; Væver, Mette S.; Køppe, Simo; Cohen, David; Chetouani, Mohamed

2017-01-01

Bodily movements are an essential component of social interactions. However, the role of movement in early mother-infant interaction has received little attention in the research literature. The aim of the present study was to investigate the relationship between automatically extracted motion features and interaction quality in mother-infant interactions at 4 and 13 months. The sample consisted of 19 mother-infant dyads at 4 months and 33 mother-infant dyads at 13 months. The coding system Coding Interactive Behavior (CIB) was used for rating the quality of the interactions. Kinetic energy of upper-body, arms and head motion was calculated and used as segmentation in order to extract coarse- and fine-grained motion features. Spearman correlations were conducted between the composites derived from the CIB and the coarse- and fine-grained motion features. At both 4 and 13 months, longer durations of maternal arm motion and infant upper-body motion were associated with more aversive interactions, i.e., more parent-led interactions and more infant negativity. Further, at 4 months, the amount of motion silence was related to more adaptive interactions, i.e., more sensitive and child-led interactions. Analyses of the fine-grained motion features showed that if the mother coordinates her head movements with her infant's head movements, the interaction is rated as more adaptive in terms of less infant negativity and less dyadic negative states. We found more and stronger correlations between the motion features and the interaction qualities at 4 compared to 13 months. These results highlight that motion features are related to the quality of mother-infant interactions. Factors such as infant age and interaction set-up are likely to modify the meaning and importance of different motion features. PMID:29326626

Relations between Automatically Extracted Motion Features and the Quality of Mother-Infant Interactions at 4 and 13 Months.

PubMed

Egmose, Ida; Varni, Giovanna; Cordes, Katharina; Smith-Nielsen, Johanne; Væver, Mette S; Køppe, Simo; Cohen, David; Chetouani, Mohamed

2017-01-01

Bodily movements are an essential component of social interactions. However, the role of movement in early mother-infant interaction has received little attention in the research literature. The aim of the present study was to investigate the relationship between automatically extracted motion features and interaction quality in mother-infant interactions at 4 and 13 months. The sample consisted of 19 mother-infant dyads at 4 months and 33 mother-infant dyads at 13 months. The coding system Coding Interactive Behavior (CIB) was used for rating the quality of the interactions. Kinetic energy of upper-body, arms and head motion was calculated and used as segmentation in order to extract coarse- and fine-grained motion features. Spearman correlations were conducted between the composites derived from the CIB and the coarse- and fine-grained motion features. At both 4 and 13 months, longer durations of maternal arm motion and infant upper-body motion were associated with more aversive interactions, i.e., more parent-led interactions and more infant negativity. Further, at 4 months, the amount of motion silence was related to more adaptive interactions, i.e., more sensitive and child-led interactions. Analyses of the fine-grained motion features showed that if the mother coordinates her head movements with her infant's head movements, the interaction is rated as more adaptive in terms of less infant negativity and less dyadic negative states. We found more and stronger correlations between the motion features and the interaction qualities at 4 compared to 13 months. These results highlight that motion features are related to the quality of mother-infant interactions. Factors such as infant age and interaction set-up are likely to modify the meaning and importance of different motion features.

Multi-scale dynamics and relaxation of a tethered membrane in a solvent by Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Pandey, Ras; Anderson, Kelly; Farmer, Barry

2006-03-01

A tethered membrane modeled by a flexible sheet dissipates entropy as it wrinkles and crumples. Nodes of a coarse grained membrane are connected via multiple pathways for dynamical modes to propagate. We consider a sheet with nodes connected by fluctuating bonds on a cubic lattice. The empty lattice sites constitute an effective solvent medium via node-solvent interaction. Each node execute its stochastic motion with the Metropolis algorithm subject to bond fluctuations, excluded volume constraints, and interaction energy. Dynamics and conformation of the sheet are examined at a low and a high temperature with attractive and repulsive node-node interactions for the contrast in an attractive solvent medium. Variations of the mean square displacement of the center node of the sheet and that of its center of mass with the time steps are examined in detail which show different power-law motion from short to long time regimes. Relaxation of the gyration radius and scaling of its asymptotic value with the molecular weight are examined.

Generation of animation sequences of three dimensional models

NASA Technical Reports Server (NTRS)

Poi, Sharon (Inventor); Bell, Brad N. (Inventor)

1990-01-01

The invention is directed toward a method and apparatus for generating an animated sequence through the movement of three-dimensional graphical models. A plurality of pre-defined graphical models are stored and manipulated in response to interactive commands or by means of a pre-defined command file. The models may be combined as part of a hierarchical structure to represent physical systems without need to create a separate model which represents the combined system. System motion is simulated through the introduction of translation, rotation and scaling parameters upon a model within the system. The motion is then transmitted down through the system hierarchy of models in accordance with hierarchical definitions and joint movement limitations. The present invention also calls for a method of editing hierarchical structure in response to interactive commands or a command file such that a model may be included, deleted, copied or moved within multiple system model hierarchies. The present invention also calls for the definition of multiple viewpoints or cameras which may exist as part of a system hierarchy or as an independent camera. The simulated movement of the models and systems is graphically displayed on a monitor and a frame is recorded by means of a video controller. Multiple movement and hierarchy manipulations are then recorded as a sequence of frames which may be played back as an animation sequence on a video cassette recorder.

Three-Dimensional Motion Estimation Using Shading Information in Multiple Frames

DTIC Science & Technology

1989-09-01

j. Threle-D.imensionai GO Motion Estimation U sing, Shadin g Ilnformation in Multiple Frames- IJean-Pierre Schotf MIT Artifi -cial intelligence...vision 3-D structure 3-D vision- shape from shading multiple frames 20. ABSTRACT (Cofrn11,00 an reysrf* OWd Of Rssss00n7 Ad 4111111& F~ block f)nseq See...motion and shading have been treated as two disjoint problems. On the one hand, researchers studying motion or structure from motion often assume

The Effects of System and Environmental Factors Upon Experienced Pilot Performance in the Advanced Simulator for Pilot Training

DTIC Science & Technology

1977-04-01

System by System Variable Interactions Across All Maneuvers ... .......... 23 11 Field of View by Motion Interaction Cell Means for Takeoff...23 12 Motion by Field :f View Interaction Cell Means for GCA ..... ................. 24 13 Motion by FOV Interaction Mc--n Ratings for the...GCA and Takeoff Maneuvers ... ....... 24 14 Motion by G.Seat Interaction Cell Means for Takeoff ...... ................... 25 15 Motion by G.Seat

A Real-Time High Performance Computation Architecture for Multiple Moving Target Tracking Based on Wide-Area Motion Imagery via Cloud and Graphic Processing Units

PubMed Central

Liu, Kui; Wei, Sixiao; Chen, Zhijiang; Jia, Bin; Chen, Genshe; Ling, Haibin; Sheaff, Carolyn; Blasch, Erik

2017-01-01

This paper presents the first attempt at combining Cloud with Graphic Processing Units (GPUs) in a complementary manner within the framework of a real-time high performance computation architecture for the application of detecting and tracking multiple moving targets based on Wide Area Motion Imagery (WAMI). More specifically, the GPU and Cloud Moving Target Tracking (GC-MTT) system applied a front-end web based server to perform the interaction with Hadoop and highly parallelized computation functions based on the Compute Unified Device Architecture (CUDA©). The introduced multiple moving target detection and tracking method can be extended to other applications such as pedestrian tracking, group tracking, and Patterns of Life (PoL) analysis. The cloud and GPUs based computing provides an efficient real-time target recognition and tracking approach as compared to methods when the work flow is applied using only central processing units (CPUs). The simultaneous tracking and recognition results demonstrate that a GC-MTT based approach provides drastically improved tracking with low frame rates over realistic conditions. PMID:28208684

A Real-Time High Performance Computation Architecture for Multiple Moving Target Tracking Based on Wide-Area Motion Imagery via Cloud and Graphic Processing Units.

PubMed

Liu, Kui; Wei, Sixiao; Chen, Zhijiang; Jia, Bin; Chen, Genshe; Ling, Haibin; Sheaff, Carolyn; Blasch, Erik

2017-02-12

This paper presents the first attempt at combining Cloud with Graphic Processing Units (GPUs) in a complementary manner within the framework of a real-time high performance computation architecture for the application of detecting and tracking multiple moving targets based on Wide Area Motion Imagery (WAMI). More specifically, the GPU and Cloud Moving Target Tracking (GC-MTT) system applied a front-end web based server to perform the interaction with Hadoop and highly parallelized computation functions based on the Compute Unified Device Architecture (CUDA©). The introduced multiple moving target detection and tracking method can be extended to other applications such as pedestrian tracking, group tracking, and Patterns of Life (PoL) analysis. The cloud and GPUs based computing provides an efficient real-time target recognition and tracking approach as compared to methods when the work flow is applied using only central processing units (CPUs). The simultaneous tracking and recognition results demonstrate that a GC-MTT based approach provides drastically improved tracking with low frame rates over realistic conditions.

Learning to represent spatial transformations with factored higher-order Boltzmann machines.

PubMed

Memisevic, Roland; Hinton, Geoffrey E

2010-06-01

To allow the hidden units of a restricted Boltzmann machine to model the transformation between two successive images, Memisevic and Hinton (2007) introduced three-way multiplicative interactions that use the intensity of a pixel in the first image as a multiplicative gain on a learned, symmetric weight between a pixel in the second image and a hidden unit. This creates cubically many parameters, which form a three-dimensional interaction tensor. We describe a low-rank approximation to this interaction tensor that uses a sum of factors, each of which is a three-way outer product. This approximation allows efficient learning of transformations between larger image patches. Since each factor can be viewed as an image filter, the model as a whole learns optimal filter pairs for efficiently representing transformations. We demonstrate the learning of optimal filter pairs from various synthetic and real image sequences. We also show how learning about image transformations allows the model to perform a simple visual analogy task, and we show how a completely unsupervised network trained on transformations perceives multiple motions of transparent dot patterns in the same way as humans.

The Complex Structure of Receptive Fields in the Middle Temporal Area

PubMed Central

Richert, Micah; Albright, Thomas D.; Krekelberg, Bart

2012-01-01

Neurons in the middle temporal area (MT) are often viewed as motion detectors that prefer a single direction of motion in a single region of space. This assumption plays an important role in our understanding of visual processing, and models of motion processing in particular. We used extracellular recordings in area MT of awake, behaving monkeys (M. mulatta) to test this assumption with a novel reverse correlation approach. Nearly half of the MT neurons in our sample deviated significantly from the classical view. First, in many cells, direction preference changed with the location of the stimulus within the receptive field. Second, the spatial response profile often had multiple peaks with apparent gaps in between. This shows that visual motion analysis in MT has access to motion detectors that are more complex than commonly thought. This complexity could be a mere byproduct of imperfect development, but can also be understood as the natural consequence of the non-linear, recurrent interactions among laterally connected MT neurons. An important direction for future research is to investigate whether these in homogeneities are advantageous, how they can be incorporated into models of motion detection, and whether they can provide quantitative insight into the underlying effective connectivity. PMID:23508640

Contrast, contours and the confusion effect in dazzle camouflage.

PubMed

Hogan, Benedict G; Scott-Samuel, Nicholas E; Cuthill, Innes C

2016-07-01

'Motion dazzle camouflage' is the name for the putative effects of highly conspicuous, often repetitive or complex, patterns on parameters important in prey capture, such as the perception of speed, direction and identity. Research into motion dazzle camouflage is increasing our understanding of the interactions between visual tracking, the confusion effect and defensive coloration. However, there is a paucity of research into the effects of contrast on motion dazzle camouflage: is maximal contrast a prerequisite for effectiveness? If not, this has important implications for our recognition of the phenotype and understanding of the function and mechanisms of potential motion dazzle camouflage patterns. Here we tested human participants' ability to track one moving target among many identical distractors with surface patterns designed to test the influence of these factors. In line with previous evidence, we found that targets with stripes parallel to the object direction of motion were hardest to track. However, reduction in contrast did not significantly influence this result. This finding may bring into question the utility of current definitions of motion dazzle camouflage, and means that some animal patterns, such as aposematic or mimetic stripes, may have previously unrecognized multiple functions.

Recurrent network dynamics reconciles visual motion segmentation and integration.

PubMed

Medathati, N V Kartheek; Rankin, James; Meso, Andrew I; Kornprobst, Pierre; Masson, Guillaume S

2017-09-12

In sensory systems, a range of computational rules are presumed to be implemented by neuronal subpopulations with different tuning functions. For instance, in primate cortical area MT, different classes of direction-selective cells have been identified and related either to motion integration, segmentation or transparency. Still, how such different tuning properties are constructed is unclear. The dominant theoretical viewpoint based on a linear-nonlinear feed-forward cascade does not account for their complex temporal dynamics and their versatility when facing different input statistics. Here, we demonstrate that a recurrent network model of visual motion processing can reconcile these different properties. Using a ring network, we show how excitatory and inhibitory interactions can implement different computational rules such as vector averaging, winner-take-all or superposition. The model also captures ordered temporal transitions between these behaviors. In particular, depending on the inhibition regime the network can switch from motion integration to segmentation, thus being able to compute either a single pattern motion or to superpose multiple inputs as in motion transparency. We thus demonstrate that recurrent architectures can adaptively give rise to different cortical computational regimes depending upon the input statistics, from sensory flow integration to segmentation.

On the formation modes in vortex interaction for multiple co-axial co-rotating vortex rings

NASA Astrophysics Data System (ADS)

Qin, Suyang; Liu, Hong; Xiang, Yang

2018-01-01

Interaction among multiple vortices is of particular importance to biological locomotion. It plays an essential role in the force and energy capture. This study examines the motion and dynamics of multiple co-axial co-rotating vortex rings. The vortex rings, which have the same formation time, are successively generated in a piston-cylinder apparatus by accurately controlling the interval time. The flow fields are visualized by the finite-time Lyapunov exponent and then repelling Lagrangian coherent structures (r-LCSs) are determined. Two types of vortex interactions ("strong" and "weak") are defined by investigating the r-LCSs: a strong interaction is indicated by connected r-LCSs showing a channel for fluid transport (termed as a "flux window"); a weak interaction is indicated by disconnected r-LCSs between the vortex rings. For strong interaction, leapfrogging and merger of vortex rings can happen in the later stage of the evolution process; however, the rings are separated for weak interaction. Two distinct formation modes, the formation enhancement mode (FEM) and formation restraint mode (FRM), refer to the effect of one or multiple vortex ring(s) on the initial circulation of the subsequently formed vortex ring. In the FEM, the circulation of a vortex ring is larger than that of an isolated (without interaction) vortex ring. On the other hand, the situation is opposite in the FRM. A dimensionless number reflecting the interaction mechanism, "structure stretching number" S*, is proposed, which evaluates the induced effect of the wake vortices on the formation of a vortex ring. A limiting S* (SL*=(2 ±0.4 ) ×1 0-4) is the bifurcation point of the two formation modes. The augmentation of circulation reaches up to 10% for the FEM when S*SL*), the circulation decreases for at most 20%. The newly defined formation modes and number could shed light on the understanding of the dynamics of multiple vortex ring flows.

Data fusion of multiple kinect sensors for a rehabilitation system.

PubMed

Huibin Du; Yiwen Zhao; Jianda Han; Zheng Wang; Guoli Song

2016-08-01

Kinect-like depth sensors have been widely used in rehabilitation systems. However, single depth sensor processes limb-blocking, data loss or data error poorly, making it less reliable. This paper focus on using two Kinect sensors and data fusion method to solve these problems. First, two Kinect sensors capture the motion data of the healthy arm of the hemiplegic patient; Second, merge the data using the method of Set-Membership-Filter (SMF); Then, mirror this motion data by the Middle-Plane; In the end, control the wearable robotic arm driving the patient's paralytic arm so that the patient can interactively and initiatively complete a variety of recovery actions prompted by computer with 3D animation games.

Three-Dimensional Tracking of Interfacial Hopping Diffusion

NASA Astrophysics Data System (ADS)

Wang, Dapeng; Wu, Haichao; Schwartz, Daniel K.

2017-12-01

Theoretical predictions have suggested that molecular motion at interfaces—which influences processes including heterogeneous catalysis, (bio)chemical sensing, lubrication and adhesion, and nanomaterial self-assembly—may be dominated by hypothetical "hops" through the adjacent liquid phase, where a diffusing molecule readsorbs after a given hop according to a probabilistic "sticking coefficient." Here, we use three-dimensional (3D) single-molecule tracking to explicitly visualize this process for human serum albumin at solid-liquid interfaces that exert varying electrostatic interactions on the biomacromolecule. Following desorption from the interface, a molecule experiences multiple unproductive surface encounters before readsorption. An average of approximately seven surface collisions is required for the repulsive surfaces, decreasing to approximately two and a half for surfaces that are more attractive. The hops themselves are also influenced by long-range interactions, with increased electrostatic repulsion causing hops of longer duration and distance. These findings explicitly demonstrate that interfacial diffusion is dominated by biased 3D Brownian motion involving bulk-surface coupling and that it can be controlled by influencing short- and long-range adsorbate-surface interactions.

Estimation of multiple accelerated motions using chirp-Fourier transform and clustering.

PubMed

Alexiadis, Dimitrios S; Sergiadis, George D

2007-01-01

Motion estimation in the spatiotemporal domain has been extensively studied and many methodologies have been proposed, which, however, cannot handle both time-varying and multiple motions. Extending previously published ideas, we present an efficient method for estimating multiple, linearly time-varying motions. It is shown that the estimation of accelerated motions is equivalent to the parameter estimation of superpositioned chirp signals. From this viewpoint, one can exploit established signal processing tools such as the chirp-Fourier transform. It is shown that accelerated motion results in energy concentration along planes in the 4-D space: spatial frequencies-temporal frequency-chirp rate. Using fuzzy c-planes clustering, we estimate the plane/motion parameters. The effectiveness of our method is verified on both synthetic as well as real sequences and its advantages are highlighted.

Case report: paradoxical ventricular septal motion in the setting of primary right ventricular myocardial failure.

PubMed

Maslow, Andrew; Schwartz, Carl; Mahmood, Feroze; Singh, Arun; Heerdt, Paul M

2009-07-01

In this report, a case of right ventricular (RV) failure, hemodynamic instability, and systemic organ failure is described to highlight how paradoxical ventricular systolic septal motion (PVSM), or a rightward systolic displacement of the interventricular septum, may contribute to RV ejection. Multiple inotropic medications and vasopressors were administered to treat right heart failure and systemic hypotension in a patient following combined aortic and mitral valve replacement. In the early postoperative period, echocardiographic evaluation revealed adequate left ventricular systolic function, akinesis of the RV myocardial tissues, and PVSM. In the presence of PVSM, RV fractional area of contraction was > or =35% despite akinesis of the primary RV myocardial walls. The PVSM appeared to contribute toward RV ejection. As a result, the need for multiple inotropes was re-evaluated, in considering that end-organ dysfunction was the result of systemic hypotension and prolonged vasopressor administration. After discontinuation of phosphodiesterase inhibitors, native vascular tone returned and the need for vasopressors declined. This was followed by recovery of systemic organ function. Echocardiographic re-evaluation two years later, revealed persistent akinesis of the RV myocardial tissues and PVSM, the latter appearing to contribute toward RV ejection. This case highlights the importance of left to RV interactions, and how PVSM may mediate these hemodynamic interactions.

Activity loss by H46A mutation in Mycobacterium tuberculosis isocitrate lyase is due to decrease in structural plasticity and collective motions of the active site.

PubMed

Shukla, Rohit; Shukla, Harish; Tripathi, Timir

2018-01-01

Mycobacterium tuberculosis isocitrate lyase (MtbICL) is a crucial enzyme of the glyoxylate cycle and is a validated anti-tuberculosis drug target. Structurally distant, non-active site mutation (H46A) in MtbICL has been found to cause loss of enzyme activity. The aim of the present work was to explore the structural alterations induced by H46A mutation that caused the loss of enzyme activity. The structural and dynamic consequences of H46A mutation were studied using multiple computational methods such as docking, molecular dynamics simulation and residue interaction network analysis (RIN). Principal component analysis and cross correlation analysis revealed the difference in conformational flexibility and collective modes of motions between the wild-type and mutant enzyme, particularly in the active site region. RIN analysis revealed that the active site geometry was disturbed in the mutant enzyme. Thus, the dynamic perturbation of the active site led to enzyme transition from its active form to inactive form upon mutation. The computational analyses elucidated the mutant-specific conformational alterations, differential dominant motions, and anomalous residue level interactions that contributed to the abrogated function of mutant MtbICL. An understanding of interactions of mutant enzymes may help in modifying the existing drugs and designing improved drugs for successful control of tuberculosis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Portable color multimedia training systems based on monochrome laptop computers (CBT-in-a-briefcase), with spinoff implications for video uplink and downlink in spaceflight operations

NASA Technical Reports Server (NTRS)

Scott, D. W.

1994-01-01

This report describes efforts to use digital motion video compression technology to develop a highly portable device that would convert 1990-91 era IBM-compatible and/or MacIntosh notebook computers into full-color, motion-video capable multimedia training systems. An architecture was conceived that would permit direct conversion of existing laser-disk-based multimedia courses with little or no reauthoring. The project did not physically demonstrate certain critical video keying techniques, but their implementation should be feasible. This investigation of digital motion video has spawned two significant spaceflight projects at MSFC: one to downlink multiple high-quality video signals from Spacelab, and the other to uplink videoconference-quality video in realtime and high quality video off-line, plus investigate interactive, multimedia-based techniques for enhancing onboard science operations. Other airborne or spaceborne spinoffs are possible.

Current induced domain wall motion and tilting in Pt/Co/Ta structures with perpendicular magnetic anisotropy in the presence of the Dyzaloshinskii–Moriya interaction

NASA Astrophysics Data System (ADS)

Yun, Jijun; Li, Dong; Cui, Baoshan; Guo, Xiaobin; Wu, Kai; Zhang, Xu; Wang, Yupei; Mao, Jian; Zuo, Yalu; Xi, Li

2018-04-01

Current induced domain wall motion (CIDWM) was studied in Pt/Co/Ta structures with perpendicular magnetic anisotropy and the Dyzaloshinskii–Moriya interaction (DMI) by the spin-orbit torque (SOT). We measured the strength of DMI and SOT efficiency in Pt/Co/Ta with the variation of the thickness of Ta using a current induced hysteresis loop shift method. The results indicate that the DMI stabilizes a chiral Néel-type domain wall (DW), and the DW motion can be driven by the enhanced large SOT generated from Pt and Ta with opposite signs of spin Hall angle in Pt/Co/Ta stacks. The CIDWM velocity, which is 104 times larger than the field driven DW velocity, obeys a creep law, and reaches around tens of meters per second with current density of ~106 A cm‑2. We also found that the Joule heating accompanied with current also accelerates the DW motion. Meanwhile, a domain wall tilting was observed, which increases with current density increasing. These results can be explained by the spin Hall effect generated from both heavy metals Pt and Ta, inherent DMI, and the current accompanying Joule heating effect. Our results could provide some new designing prospects to move multiple DWs by SOT for achieving racetrack memories.

Filling-in visual motion with sounds.

PubMed

Väljamäe, A; Soto-Faraco, S

2008-10-01

Information about the motion of objects can be extracted by multiple sensory modalities, and, as a consequence, object motion perception typically involves the integration of multi-sensory information. Often, in naturalistic settings, the flow of such information can be rather discontinuous (e.g. a cat racing through the furniture in a cluttered room is partly seen and partly heard). This study addressed audio-visual interactions in the perception of time-sampled object motion by measuring adaptation after-effects. We found significant auditory after-effects following adaptation to unisensory auditory and visual motion in depth, sampled at 12.5 Hz. The visually induced (cross-modal) auditory motion after-effect was eliminated if visual adaptors flashed at half of the rate (6.25 Hz). Remarkably, the addition of the high-rate acoustic flutter (12.5 Hz) to this ineffective, sparsely time-sampled, visual adaptor restored the auditory after-effect to a level comparable to what was seen with high-rate bimodal adaptors (flashes and beeps). Our results suggest that this auditory-induced reinstatement of the motion after-effect from the poor visual signals resulted from the occurrence of sound-induced illusory flashes. This effect was found to be dependent both on the directional congruency between modalities and on the rate of auditory flutter. The auditory filling-in of time-sampled visual motion supports the feasibility of using reduced frame rate visual content in multisensory broadcasting and virtual reality applications.

Superfluid Boson-Fermion Mixture: Structure Formation and Collective Periodic Motion

NASA Astrophysics Data System (ADS)

Mitra, A.

2018-01-01

Multiple periodic domain formation due to a modulation instability in a boson-fermion mixture superfluid in the unitary regime has been studied. The periodicity of the structure evolves with time. At the early stage of evolution, bosonic domains show the periodic nature, whereas the periodicity in the fermionic (Cooper pair) domains appears at the late stage of evolution. The nature of interatomic interspecies interactions affects the domain formation. In a harmonic trap, the mixture executes an undamped oscillation. The frequency of the oscillation depends on the relative coupling strength between boson-fermion and fermion-fermion. The repulsive boson-fermion interaction reduces the oscillation frequency, whereas the attractive interaction enhances the frequency significantly.

Results of a multi-media multiple behavior obesity prevention program for adolescents.

PubMed

Mauriello, Leanne M; Ciavatta, Mary Margaret H; Paiva, Andrea L; Sherman, Karen J; Castle, Patricia H; Johnson, Janet L; Prochaska, Janice M

2010-12-01

This study reports on effectiveness trial outcomes of Health in Motion, a computer tailored multiple behavior intervention for adolescents. Using school as level of assignment, students (n=1800) from eight high schools in four states (RI, TN, MA, and NY) were stratified and randomly assigned to no treatment or a multi-media intervention for physical activity, fruit and vegetable consumption, and limited TV viewing between 2006 and 2007. Intervention effects on continuous outcomes, on movement to action and maintenance stages, and on stability within action and maintenance stages were evaluated using random effects modeling. Effects were most pronounced for fruit and vegetable consumption and for total risks across all time points and for each behavior immediately post intervention. Co-variation of behavior change occurred within the treatment group, where individuals progressing to action or maintenance for one behavior were 1.4-4.2 times more likely to make similar progress on another behavior. Health in Motion is an innovative, multiple behavior obesity prevention intervention relevant for all adolescents that relies solely on interactive technology to deliver tailored feedback. The outcomes of the effectiveness trial demonstrate both an ability to initiate behavior change across multiple energy balance behaviors simultaneously and feasibility for ease of dissemination. Copyright © 2010 The Institute For Cancer Prevention. Published by Elsevier Inc. All rights reserved.

A 23Na Multiple-Quantum-Filtered NMR Study of the Effect of the Cytoskeleton Conformation on the Anisotropic Motion of Sodium Ions in Red Blood Cells

NASA Astrophysics Data System (ADS)

Knubovets, Tatyana; Shinar, Hadassah; Eliav, Uzi; Navon, Gil

1996-01-01

Recently, it has been shown that23Na double-quantum-filtered NMR spectroscopy can be used to detect anisotropic motion of bound sodium ions in biological systems. The technique is based on the formation of the second-rank tensor when the quadrupolar interaction is not averaged to zero. Using this method, anisotropic motion of bound sodium in human and dog red blood cells was detected, and the effect was shown to depend on the integrity of the membrane cytoskeleton. In the present study, multiple-quantum-filtered techniques were applied in combination with a quadrupolar echo to measure the transverse-relaxation times,T2fandT2s. Line fitting was performed to obtain the values of the residual quadrupolar interaction, which was measured for sodium in a variety of mammalian erythrocytes of different size, shape, rheological properties, and sodium concentrations. Human unsealed white ghosts were used to study sodium bound at the anisotropic sites on the inner side of the RBC membrane. Modulations of the conformation of the cytoskeleton by the variation of either the ionic strength or pH of the suspending medium caused drastic changes in both the residual quadrupolar interaction andT2fdue to changes in the fraction of bound sodium ions as well as changes in the structure of the binding sites. By combining the two spectroscopic parameters, structural change can be followed. The changes in the structure of the sodium anisotropic binding sites deduced by this method were found to correlate with known conformational changes of the membrane cytoskeleton. Variations of the medium pH affected both the fraction of bound sodium ions and the structure of the anisotropic binding sites. Sodium and potassium were shown to bind to the anisotropic binding sites with the same affinity.

Estimation of Finger Joint Angles Based on Electromechanical Sensing of Wrist Shape.

PubMed

Kawaguchi, Junki; Yoshimoto, Shunsuke; Kuroda, Yoshihiro; Oshiro, Osamu

2017-09-01

An approach to finger motion capture that places fewer restrictions on the usage environment and actions of the user is an important research topic in biomechanics and human-computer interaction. We proposed a system that electrically detects finger motion from the associated deformation of the wrist and estimates the finger joint angles using multiple regression models. A wrist-mounted sensing device with 16 electrodes detects deformation of the wrist from changes in electrical contact resistance at the skin. In this study, we experimentally investigated the accuracy of finger joint angle estimation, the adequacy of two multiple regression models, and the resolution of the estimation of total finger joint angles. In experiments, both the finger joint angles and the system output voltage were recorded as subjects performed flexion/extension of the fingers. These data were used for calibration using the least-squares method. The system was found to be capable of estimating the total finger joint angle with a root-mean-square error of 29-34 degrees. A multiple regression model with a second-order polynomial basis function was shown to be suitable for the estimation of all total finger joint angles, but not those of the thumb.

How visual illusions illuminate complementary brain processes: illusory depth from brightness and apparent motion of illusory contours

PubMed Central

Grossberg, Stephen

2014-01-01

Neural models of perception clarify how visual illusions arise from adaptive neural processes. Illusions also provide important insights into how adaptive neural processes work. This article focuses on two illusions that illustrate a fundamental property of global brain organization; namely, that advanced brains are organized into parallel cortical processing streams with computationally complementary properties. That is, in order to process certain combinations of properties, each cortical stream cannot process complementary properties. Interactions between these streams, across multiple processing stages, overcome their complementary deficiencies to compute effective representations of the world, and to thereby achieve the property of complementary consistency. The two illusions concern how illusory depth can vary with brightness, and how apparent motion of illusory contours can occur. Illusory depth from brightness arises from the complementary properties of boundary and surface processes, notably boundary completion and surface-filling in, within the parvocellular form processing cortical stream. This illusion depends upon how surface contour signals from the V2 thin stripes to the V2 interstripes ensure complementary consistency of a unified boundary/surface percept. Apparent motion of illusory contours arises from the complementary properties of form and motion processes across the parvocellular and magnocellular cortical processing streams. This illusion depends upon how illusory contours help to complete boundary representations for object recognition, how apparent motion signals can help to form continuous trajectories for target tracking and prediction, and how formotion interactions from V2-to-MT enable completed object representations to be continuously tracked even when they move behind intermittently occluding objects through time. PMID:25389399

An Experimental Investigation of Intermittent Flow and Strain Burst Scaling Behavior in LiF Crystals During Microcompression Testing (Preprint)

DTIC Science & Technology

2010-01-01

or in more general terms, as a result of dislocation nucleation, motion, multiplication, and interaction). Nonetheless, state-of-the-art simulation ...computational power, together with under-developed physics within the simulation codes (i.e. cross-slip, climb, crystal rotations and patterning to...name a few), prevent realistic dislocation simulations over temporal and spatial domains that are readily accessible by experimental methods [9, 10

Interscale energy transfer in the merger of wakes of a multiscale array of rectangular cylinders

NASA Astrophysics Data System (ADS)

Baj, Pawel; Buxton, Oliver R. H.

2017-11-01

The near wake of a flow past a multiscale array of bars is studied by means of particle image velocimetry (PIV). The aim of this research is to understand the nature of multiscale flows, where multiple coherent motions of nonuniform sizes and characteristic frequencies (i.e., sheddings of particular bars in our considered case) interact with each other. The velocity fields acquired from the experiments are triple decomposed into their mean, a number of coherent fluctuations, and their stochastic part according to a triple decomposition technique introduced recently by Baj et al., Phys. Fluids 27, 075104 (2015), 10.1063/1.4923744. This nonstandard approach allows us to monitor the interactions between different coherent fluctuations representative of sheddings of the particular bars. Further, additional equations governing the kinetic energy of the recognized velocity components are derived to provide better insight into the dynamics of these interactions. Interestingly, apart from the coherent fluctuations associated with sheddings, some additional, secondary coherent fluctuations are also recognized. These seem to appear as a result of nonlinear triadic interactions between the primary shedding modes when the two shedding structures of different characteristic frequencies are in close proximity to one another. The secondary coherent motions are almost exclusively supplied with energy by the primary coherent motions, whereas the latter are driven by the mean flow. It is also found that the coherent fluctuations play an important role in exciting the stochastic fluctuations, as the energy is not fed to the stochastic fluctuations directly from the mean flow but rather through the coherent modes.

Integrated fMRI Preprocessing Framework Using Extended Kalman Filter for Estimation of Slice-Wise Motion

PubMed Central

Pinsard, Basile; Boutin, Arnaud; Doyon, Julien; Benali, Habib

2018-01-01

Functional MRI acquisition is sensitive to subjects' motion that cannot be fully constrained. Therefore, signal corrections have to be applied a posteriori in order to mitigate the complex interactions between changing tissue localization and magnetic fields, gradients and readouts. To circumvent current preprocessing strategies limitations, we developed an integrated method that correct motion and spatial low-frequency intensity fluctuations at the level of each slice in order to better fit the acquisition processes. The registration of single or multiple simultaneously acquired slices is achieved online by an Iterated Extended Kalman Filter, favoring the robust estimation of continuous motion, while an intensity bias field is non-parametrically fitted. The proposed extraction of gray-matter BOLD activity from the acquisition space to an anatomical group template space, taking into account distortions, better preserves fine-scale patterns of activity. Importantly, the proposed unified framework generalizes to high-resolution multi-slice techniques. When tested on simulated and real data the latter shows a reduction of motion explained variance and signal variability when compared to the conventional preprocessing approach. These improvements provide more stable patterns of activity, facilitating investigation of cerebral information representation in healthy and/or clinical populations where motion is known to impact fine-scale data. PMID:29755312

Integrated fMRI Preprocessing Framework Using Extended Kalman Filter for Estimation of Slice-Wise Motion.

PubMed

Pinsard, Basile; Boutin, Arnaud; Doyon, Julien; Benali, Habib

2018-01-01

Functional MRI acquisition is sensitive to subjects' motion that cannot be fully constrained. Therefore, signal corrections have to be applied a posteriori in order to mitigate the complex interactions between changing tissue localization and magnetic fields, gradients and readouts. To circumvent current preprocessing strategies limitations, we developed an integrated method that correct motion and spatial low-frequency intensity fluctuations at the level of each slice in order to better fit the acquisition processes. The registration of single or multiple simultaneously acquired slices is achieved online by an Iterated Extended Kalman Filter, favoring the robust estimation of continuous motion, while an intensity bias field is non-parametrically fitted. The proposed extraction of gray-matter BOLD activity from the acquisition space to an anatomical group template space, taking into account distortions, better preserves fine-scale patterns of activity. Importantly, the proposed unified framework generalizes to high-resolution multi-slice techniques. When tested on simulated and real data the latter shows a reduction of motion explained variance and signal variability when compared to the conventional preprocessing approach. These improvements provide more stable patterns of activity, facilitating investigation of cerebral information representation in healthy and/or clinical populations where motion is known to impact fine-scale data.

Superdiffusion, large-scale synchronization, and topological defects

NASA Astrophysics Data System (ADS)

Großmann, Robert; Peruani, Fernando; Bär, Markus

2016-04-01

We study an ensemble of random walkers carrying internal noisy phase oscillators which are synchronized among the walkers by local interactions. Due to individual mobility, the interaction partners of every walker change randomly, hereby introducing an additional, independent source of fluctuations, thus constituting the intrinsic nonequilibrium nature of the temporal dynamics. We employ this paradigmatic model system to discuss how the emergence of order is affected by the motion of individual entities. In particular, we consider both normal diffusive motion and superdiffusion. A non-Hamiltonian field theory including multiplicative noise terms is derived which describes the nonequilibrium dynamics at the macroscale. This theory reveals a defect-mediated transition from incoherence to quasi-long-range order for normal diffusion of oscillators in two dimensions, implying a power-law dependence of all synchronization properties on system size. In contrast, superdiffusive transport suppresses the emergence of topological defects, thereby inducing a continuous synchronization transition to long-range order in two dimensions. These results are consistent with particle-based simulations.

Perceptual interaction of local motion signals

PubMed Central

Nitzany, Eyal I.; Loe, Maren E.; Palmer, Stephanie E.; Victor, Jonathan D.

2016-01-01

Motion signals are a rich source of information used in many everyday tasks, such as segregation of objects from background and navigation. Motion analysis by biological systems is generally considered to consist of two stages: extraction of local motion signals followed by spatial integration. Studies using synthetic stimuli show that there are many kinds and subtypes of local motion signals. When presented in isolation, these stimuli elicit behavioral and neurophysiological responses in a wide range of species, from insects to mammals. However, these mathematically-distinct varieties of local motion signals typically co-exist in natural scenes. This study focuses on interactions between two kinds of local motion signals: Fourier and glider. Fourier signals are typically associated with translation, while glider signals occur when an object approaches or recedes. Here, using a novel class of synthetic stimuli, we ask how distinct kinds of local motion signals interact and whether context influences sensitivity to Fourier motion. We report that local motion signals of different types interact at the perceptual level, and that this interaction can include subthreshold summation and, in some subjects, subtle context-dependent changes in sensitivity. We discuss the implications of these observations, and the factors that may underlie them. PMID:27902829

Perceptual interaction of local motion signals.

PubMed

Nitzany, Eyal I; Loe, Maren E; Palmer, Stephanie E; Victor, Jonathan D

2016-11-01

Motion signals are a rich source of information used in many everyday tasks, such as segregation of objects from background and navigation. Motion analysis by biological systems is generally considered to consist of two stages: extraction of local motion signals followed by spatial integration. Studies using synthetic stimuli show that there are many kinds and subtypes of local motion signals. When presented in isolation, these stimuli elicit behavioral and neurophysiological responses in a wide range of species, from insects to mammals. However, these mathematically-distinct varieties of local motion signals typically co-exist in natural scenes. This study focuses on interactions between two kinds of local motion signals: Fourier and glider. Fourier signals are typically associated with translation, while glider signals occur when an object approaches or recedes. Here, using a novel class of synthetic stimuli, we ask how distinct kinds of local motion signals interact and whether context influences sensitivity to Fourier motion. We report that local motion signals of different types interact at the perceptual level, and that this interaction can include subthreshold summation and, in some subjects, subtle context-dependent changes in sensitivity. We discuss the implications of these observations, and the factors that may underlie them.

An inventory on rotational kinematics of a particle: unravelling misconceptions and pitfalls in reasoning

NASA Astrophysics Data System (ADS)

Mashood, K. K.; Singh, Vijay A.

2012-09-01

Student difficulties regarding the angular velocity (\\vec{\\omega }) and angular acceleration (\\vec{\\alpha }) of a particle have remained relatively unexplored in contrast to their linear counterparts. We present an inventory comprising multiple choice questions aimed at probing misconceptions and eliciting ill-suited reasoning patterns. The development of the inventory was based on interactions with students, teachers and experts. We report misconceptions, some of which are parallel to those found earlier in linear kinematics. Fixations with inappropriate prototypes were uncovered. Many students and even teachers mistakenly assume that all rotational motion is necessarily circular. A persistent notion that the direction of \\vec{\\omega } and \\vec{\\alpha } should be ‘along’ the motion exists. Instances of indiscriminate usage of equations were identified.

Techniques for efficient, real-time, 3D visualization of multi-modality cardiac data using consumer graphics hardware.

PubMed

Levin, David; Aladl, Usaf; Germano, Guido; Slomka, Piotr

2005-09-01

We exploit consumer graphics hardware to perform real-time processing and visualization of high-resolution, 4D cardiac data. We have implemented real-time, realistic volume rendering, interactive 4D motion segmentation of cardiac data, visualization of multi-modality cardiac data and 3D display of multiple series cardiac MRI. We show that an ATI Radeon 9700 Pro can render a 512x512x128 cardiac Computed Tomography (CT) study at 0.9 to 60 frames per second (fps) depending on rendering parameters and that 4D motion based segmentation can be performed in real-time. We conclude that real-time rendering and processing of cardiac data can be implemented on consumer graphics cards.

Multiple effects of S13 in modulating the strength of intersubunit interactions in the ribosome during translation.

PubMed

Cukras, Anthony R; Green, Rachel

2005-05-27

The ribosomal protein S13 is found in the head region of the small subunit, where it interacts with the central protuberance of the large ribosomal subunit and with the P site-bound tRNA through its extended C terminus. The bridging interactions between the large and small subunits are dynamic, and are thought to be critical in orchestrating the molecular motions of the translation cycle. S13 provides a direct link between the tRNA-binding site and the movements in the head of the small subunit seen during translocation, thereby providing a possible pathway of signal transduction. We have created and characterized an rpsM(S13)-deficient strain of Escherichia coli and have found significant defects in subunit association, initiation and translocation through in vitro assays of S13-deficient ribosomes. Targeted mutagenesis of specific bridge and tRNA contact elements in S13 provides evidence that these two interaction domains play critical roles in maintaining the fidelity of translation. This ribosomal protein thus appears to play a non-essential, yet important role by modulating subunit interactions in multiple steps of the translation cycle.

Bottom boundary layer forced by finite amplitude long and short surface waves motions

NASA Astrophysics Data System (ADS)

Elsafty, H.; Lynett, P.

2018-04-01

A multiple-scale perturbation approach is implemented to solve the Navier-Stokes equations while including bottom boundary layer effects under a single wave and under two interacting waves. In this approach, fluid velocities and the pressure field are decomposed into two components: a potential component and a rotational component. In this study, the two components are exist throughout the entire water column and each is scaled with appropriate length and time scales. A one-way coupling between the two components is implemented. The potential component is assumed to be known analytically or numerically a prior, and the rotational component is forced by the potential component. Through order of magnitude analysis, it is found that the leading-order coupling between the two components occurs through the vertical convective acceleration. It is shown that this coupling plays an important role in the bottom boundary layer behavior. Its effect on the results is discussed for different wave-forcing conditions: purely harmonic forcing and impurely harmonic forcing. The approach is then applied to derive the governing equations for the bottom boundary layer developed under two interacting wave motions. Both motions-the shorter and the longer wave-are decomposed into two components, potential and rotational, as it is done in the single wave. Test cases are presented wherein two different wave forcings are simulated: (1) two periodic oscillatory motions and (2) short waves interacting with a solitary wave. The analysis of the two periodic motions indicates that nonlinear effects in the rotational solution may be significant even though nonlinear effects are negligible in the potential forcing. The local differences in the rotational velocity due to the nonlinear vertical convection coupling term are found to be on the order of 30% of the maximum boundary layer velocity for the cases simulated in this paper. This difference is expected to increase with the increase in wave nonlinearity.

Constraints from Seamounts on Pacific Plate or Plume Motion Prior to 80 Ma.

NASA Astrophysics Data System (ADS)

Konter, J. G.; Koppers, A. A. P.; Jackson, M. G.; Finlayson, V.; Konrad, K.

2015-12-01

The Hawaii-Emperor and Louisville hotspot tracks have long dominated the data set constraining absolute plate motion models. However, prior to ~80 Ma, multiple shorter, discontinuous hotspot trails and oceanic plateaus have been used to constrain absolute plate motion. Based on this earlier work, a clear Hawaii-Emperor style bend seems apparent around 100 Ma in the West Pacific Seamount Province (WPSP). More importantly, the ongoing debate on a plate versus plume motion origin for the Hawaii-Emperor Bend is applicable here, as the ~100 Ma bend may correspond to a global plate reorganization (Matthews et al., EPSL, 2012). Data for a comparison of bends comes from three groups with similar geographic patterns: 1) Mid-Pacific Mountains, Line Islands; 2) Shatsky Rise, Hess Rise, Musician and Wentworth Seamounts; and 3) Wake Seamounts, Marshall Islands, Magellan Seamounts. Both groups 1 and 2 feature a large igneous province (LIP) at their oldest end: Shatsky Rise and the Mid-Pacific Mountains. According to plate reconstructions these LIPs were constructed near all-ridge triple junctions, thus potential plume-ridge interactions need to be clarified before these LIPs can be used to define an absolute mantle reference frame. In contrast, the volcanoes of the third group (Wake, Marshall, Magellan) did erupt truly intra-plate and we therefore argue that this group provides a constraint on plate motion beyond 80 Ma that is independent of plume-ridge interactions. Since the volcanoes in this group are part of the WPSP, which is densely populated with seamounts, a combination of 40Ar/39Ar ages and Sr-Nd-Pb-Hf isotopes is needed to distinguish different hotspot tracks in this region. Backtracking each volcano through its age to its original eruptive location and using compositional color-coding, reveals groupings and patterns that vary by plate motion model, while the temporal patterns of backtracked locations inform us about potential plume motions.

A Mechanistic Model for Cooperative Behavior of Co-transcribing RNA Polymerases

PubMed Central

Heberling, Tamra; Davis, Lisa; Gedeon, Jakub; Morgan, Charles; Gedeon, Tomáš

2016-01-01

In fast-transcribing prokaryotic genes, such as an rrn gene in Escherichia coli, many RNA polymerases (RNAPs) transcribe the DNA simultaneously. Active elongation of RNAPs is often interrupted by pauses, which has been observed to cause RNAP traffic jams; yet some studies indicate that elongation seems to be faster in the presence of multiple RNAPs than elongation by a single RNAP. We propose that an interaction between RNAPs via the torque produced by RNAP motion on helically twisted DNA can explain this apparent paradox. We have incorporated the torque mechanism into a stochastic model and simulated transcription both with and without torque. Simulation results illustrate that the torque causes shorter pause durations and fewer collisions between polymerases. Our results suggest that the torsional interaction of RNAPs is an important mechanism in maintaining fast transcription times, and that transcription should be viewed as a cooperative group effort by multiple polymerases. PMID:27517607

Vestibular system: the many facets of a multimodal sense.

PubMed

Angelaki, Dora E; Cullen, Kathleen E

2008-01-01

Elegant sensory structures in the inner ear have evolved to measure head motion. These vestibular receptors consist of highly conserved semicircular canals and otolith organs. Unlike other senses, vestibular information in the central nervous system becomes immediately multisensory and multimodal. There is no overt, readily recognizable conscious sensation from these organs, yet vestibular signals contribute to a surprising range of brain functions, from the most automatic reflexes to spatial perception and motor coordination. Critical to these diverse, multimodal functions are multiple computationally intriguing levels of processing. For example, the need for multisensory integration necessitates vestibular representations in multiple reference frames. Proprioceptive-vestibular interactions, coupled with corollary discharge of a motor plan, allow the brain to distinguish actively generated from passive head movements. Finally, nonlinear interactions between otolith and canal signals allow the vestibular system to function as an inertial sensor and contribute critically to both navigation and spatial orientation.

Reconstruction of Northeast Asian Deformation Integrated with Western Pacific Plate Subduction since 200 Ma

NASA Astrophysics Data System (ADS)

Liu, S.; Gurnis, M.; Ma, P.; Zhang, B.

2017-12-01

The configuration and kinematics of continental deformation and its marginal plate tectonics on the Earth's surface are intrinsic manifestations of plate-mantle coupling. The complex interactions of plate boundary forces result in plate motions that are dominated by slab pull and ridge push forces and the effects of mantle drag; these interactions also result in continental deformation with a complex basin-mountain architecture and evolution. The kinematics and evolution of the western Pacific subduction and northeast Asian continental-margin deformation are a first-order tectonic process whose nature and chronology remains controversial. This paper implements a "deep-time" reconstruction of the western Pacific subduction, continental accretion or collision and basin-mountain deformation in northeast Asia since 200 Ma based on a newly revised global plate model. The results demonstrate a NW-SE-oriented shortening from 200-137 Ma, a NWW-SEE-oriented extension from 136-101 Ma, a nearly N-S-oriented extension and uplift with a short-term NWW-SEE-oriented compressional inversion in northeast China from 100-67 Ma, and a NW-SE- and nearly N-S-oriented extension from 66 Ma to the present day. The western Pacific oceanic plate subducted forward under East Asia along Mudanjiang-Honshu Island during the Jurassic, and the trenches retreated to the Sikhote-Alin, North Shimanto, and South Shimanto zones from ca. 137-128 Ma, ca. 130-90 Ma, and in ca. 60 Ma, respectively. Our time-dependent analysis of plate motion and continental deformation coupling suggests that the multi-plate convergent motion and ocean-continent convergent orogeny were induced by advance subduction during the Jurassic and earliest Cretaceous. Our analysis also indicates that the intra-continent rifting and back-arc extension were triggered by trench retreat during the Cretaceous and that the subduction of oceanic ridge and arc were triggered by trench retreat during the Cenozoic. Therefore, reconstructing the history of plate motion and subduction and tracing the geological and deformation records in continents play a significant role in revealing the effects of complex plate motions and the interactions of plate boundary forces on plate-mantle coupling and plate motion-intracontinental deformation coupling.

Hydrodynamic interactions in metachronal paddling: effects of varying stroke kinematics

NASA Astrophysics Data System (ADS)

Samaee, Milad; Kasoju, Vishwa; Lai, Hong Kuan; Santhanakrishnan, Arvind

2017-11-01

Crustaceans such as shrimp and krill use a drag-based technique for propulsion, in which multiple pairs of limbs are paddled rhythmically from the tail to the head. Each limb is phase-shifted in time relative to its neighbor. Most studies of this type of metachronal swimming have focused on the jet formed in the animal's wake. However, synergistic hydrodynamic interactions between adjacent limbs in metachrony have received minimal attention. We used a dynamically scaled robotic model to experimentally investigate how variations in stroke kinematics impact inter-paddle hydrodynamic interactions and thrust generation. Physical models of limbs were fitted to the robot and paddled with two different motion profiles (MPs)-1) MP1: metachronal power stroke (PS) and metachronal recovery stroke (RS); and 2) MP2: metachronal PS and synchronous RS. Stroke frequency and amplitude were maintained constant across both MPs. Our results show that MP2 produced faster jets in the thrust-generating direction as compared to MP1. The necessity for a pause in MP2 after completion of PS by the paddles leading the motion, prior to executing the synchronous RS, aided in further downstream flow propagation. The effect of using asymmetric stroke kinematics on thrust generated will be discussed.

State Derivation of a 12-Axis Gyroscope-Free Inertial Measurement Unit

PubMed Central

Lu, Jau-Ching; Lin, Pei-Chun

2011-01-01

The derivation of linear acceleration, angular acceleration, and angular velocity states from a 12-axis gyroscope-free inertial measurement unit that utilizes four 3-axis accelerometer measurements at four distinct locations is reported. Particularly, a new algorithm which derives the angular velocity from its quadratic form and derivative form based on the context-based interacting multiple model is demonstrated. The performance of the system was evaluated under arbitrary 3-dimensional motion. PMID:22163791

Cooling and heating of the quantum motion of trapped cadmium(+) ions

NASA Astrophysics Data System (ADS)

Deslauriers, Louis

The quest for a quantum system best satisfying the stringent requirements of a quantum information processor has made tremendous progress in many fields of physics. In the last decade, trapped ions have been established as one of the most promising architectures to accomplish the task. Internal states of an ion which can have extremely long coherence time can be used to store a quantum bit, and therefore allow many gate operations before the coherence is lost. Entanglement between multiple ions can be established via Coulomb interactions mediated by appropriate laser fields. Entangling schemes usually require the ions to be initialized to near their motional ground state. The interaction of fluctuating electric fields with the motional state of the ion leads to heating and thus to decoherence for entanglement generation limiting the fidelity of quantum logic gates. Effective ground state cooling of trapped ion motion and suppression of motional heating are thus crucial to many applications of trapped ions in quantum information science. In this thesis, I describe the implementation and study of several components of a Cadmium-ion-based quantum information processor, with special emphasis on the control and decoherence of trapped ion motion. I first discuss the building and design of various ion traps that were used in this work. I also report on the use of ultrafast laser pulses to photoionize and load cadmium ions in a variety of rf Paul trap geometries. A detailed analysis of the photoionization scheme is presented, along with its dependence on controlled experimental parameters. I then describe the implementation of Raman sideband cooling on a single trapped 111Cd+ ion to the ground state of motion, where a ground state population of 97% was achieved. The efficacy of this cooling technique is discussed with respect to different initial motional state distributions and its sensitivity to the presence of motional heating. I also present an experiment where the motion of a single trapped 112Cd+ ion is sympathetically cooled by directly Doppler cooling a 114Cd+ ion in the same trap. The implications of this result are relevant to the scaling of a trapped ion quantum computer, where the unwanted motion of an ion crystal can be quenched while not affecting the internal states of the qubit ions. (Abstract shortened by UMI.)

Gravitational Grating

NASA Astrophysics Data System (ADS)

Rahvar, Sohrab

2018-05-01

In this work, we study the interaction of the electromagnetic wave (EW) from a distant quasar with the gravitational wave (GW) sourced by the binary stars. While in the regime of geometric optics, the light bending due to this interaction is negligible, we show that the phase shifting on the wavefront of an EW can produce the diffraction pattern on the observer plane. The diffraction of the light (with the wavelength of λe) by the gravitational wave playing the role of gravitational grating (with the wavelength of λg) has the diffraction angle of Δβ ˜ λe/λg. The relative motion of the observer, the source of gravitational wave and the quasar results in a relative motion of the observer through the interference pattern on the observer plane. The consequence of this fringe crossing is the modulation in the light curve of a quasar with the period of few hours in the microwave wavelength. The optical depth for the observation of this phenomenon for a Quasar with the multiple images strongly lensed by a galaxy where the light trajectory of some of the images crosses the lensing galaxy is τ ≃ 0.2. By shifting the time-delay of the light curves of the multiple images in a strong lensed quasar and removing the intrinsic variations of a quasar, our desired signals, as a new method for detection of GWs can be detected.

The Development of Children's Understanding of Speed Change: A Contributing Factor towards Commonsense Theories of Motion

ERIC Educational Resources Information Center

Hast, Michael; Howe, Christine

2013-01-01

Previous research indicates children reason in different ways about horizontal motion and motion in fall. At the same time, their understanding of motion down inclines appears to result from an interaction between horizontal and vertical motion understanding. However, this interaction is still poorly understood. Understanding of speed change may…

Modeling Local Interactions during the Motion of Cyanobacteria

PubMed Central

Galante, Amanda; Wisen, Susanne; Bhaya, Devaki; Levy, Doron

2012-01-01

Synechocystis sp., a common unicellular freshwater cyanobacterium, has been used as a model organism to study phototaxis, an ability to move in the direction of a light source. This microorganism displays a number of additional characteristics such as delayed motion, surface dependence, and a quasi-random motion, where cells move in a seemingly disordered fashion instead of in the direction of the light source, a global force on the system. These unexplained motions are thought to be modulated by local interactions between cells such as intercellular communication. In this paper, we consider only local interactions of these phototactic cells in order to mathematically model this quasi-random motion. We analyze an experimental data set to illustrate the presence of quasi-random motion and then derive a stochastic dynamic particle system modeling interacting phototactic cells. The simulations of our model are consistent with experimentally observed phototactic motion. PMID:22713858

Two-character motion analysis and synthesis.

PubMed

Kwon, Taesoo; Cho, Young-Sang; Park, Sang Il; Shin, Sung Yong

2008-01-01

In this paper, we deal with the problem of synthesizing novel motions of standing-up martial arts such as Kickboxing, Karate, and Taekwondo performed by a pair of human-like characters while reflecting their interactions. Adopting an example-based paradigm, we address three non-trivial issues embedded in this problem: motion modeling, interaction modeling, and motion synthesis. For the first issue, we present a semi-automatic motion labeling scheme based on force-based motion segmentation and learning-based action classification. We also construct a pair of motion transition graphs each of which represents an individual motion stream. For the second issue, we propose a scheme for capturing the interactions between two players. A dynamic Bayesian network is adopted to build a motion transition model on top of the coupled motion transition graph that is constructed from an example motion stream. For the last issue, we provide a scheme for synthesizing a novel sequence of coupled motions, guided by the motion transition model. Although the focus of the present work is on martial arts, we believe that the framework of the proposed approach can be conveyed to other two-player motions as well.

Charged particle dynamics in multiple colliding electromagnetic waves. Survey of random walk, Lévy flights, limit circles, attractors and structurally determinate patterns

NASA Astrophysics Data System (ADS)

Bulanov, S. V.; Esirkepov, T. Zh.; Koga, J. K.; Bulanov, S. S.; Gong, Z.; Yan, X. Q.; Kando, M.

2017-04-01

The multiple colliding laser pulse concept formulated by Bulanov et al. (Phys. Rev. Lett., vol. 104, 2010b, 220404) is beneficial for achieving an extremely high amplitude of coherent electromagnetic field. Since the topology of electric and magnetic fields of multiple colliding laser pulses oscillating in time is far from trivial and the radiation friction effects are significant in the high field limit, the dynamics of charged particles interacting with the multiple colliding laser pulses demonstrates remarkable features corresponding to random walk trajectories, limit circles, attractors, regular patterns and Lévy flights. Under extremely high intensity conditions the nonlinear dissipation mechanism stabilizes the particle motion resulting in the charged particle trajectory being located within narrow regions and in the occurrence of a new class of regular patterns made by the particle ensembles.

Design of a knee joint mechanism that adapts to individual physiology.

PubMed

Jiun-Yih Kuan; Pasch, Kenneth A; Herr, Hugh M

2014-01-01

This paper describes the design of a new knee joint mechanism, called the Adaptive Coupling Joint (ACJ). The new mechanism has an adaptive trajectory of the center of rotations (COR) that automatically matches those of the attached biological joint. The detailed design is presented as well as characterization results of the ACJ. Conventional exoskeleton and assistive devices usually consider limb joints as a one to three degrees of freedom (DOFs) joint synthesized by multiple one-DOF hinge joints in a single plane. However, the biological joints are complex and usually rotate with respect to a changing COR. As a result, the mismatch between limb joint motion and mechanical interface motion can lead to forces that cause undesired ligament and muscle length changes and internal mechanical changes. These undesired changes contribute to discomfort, as well as to the slippage and sluggish interaction between humans and devices. It is shown that the ACJ can transmit planetary torques from either active or passive devices to the limbs without altering the normal biological joint motion.

Laser light scattering review

NASA Technical Reports Server (NTRS)

Schaetzel, Klaus

1989-01-01

Since the development of laser light sources and fast digital electronics for signal processing, the classical discipline of light scattering on liquid systems experienced a strong revival plus an enormous expansion, mainly due to new dynamic light scattering techniques. While a large number of liquid systems can be investigated, ranging from pure liquids to multicomponent microemulsions, this review is largely restricted to applications on Brownian particles, typically in the submicron range. Static light scattering, the careful recording of the angular dependence of scattered light, is a valuable tool for the analysis of particle size and shape, or of their spatial ordering due to mutual interactions. Dynamic techniques, most notably photon correlation spectroscopy, give direct access to particle motion. This may be Brownian motion, which allows the determination of particle size, or some collective motion, e.g., electrophoresis, which yields particle mobility data. Suitable optical systems as well as the necessary data processing schemes are presented in some detail. Special attention is devoted to topics of current interest, like correlation over very large lag time ranges or multiple scattering.

Impaired heel to toe progression during gait is related to reduced ankle range of motion in people with Multiple Sclerosis.

PubMed

Psarakis, Michael; Greene, David; Moresi, Mark; Baker, Michael; Stubbs, Peter; Brodie, Matthew; Lord, Stephen; Hoang, Phu

2017-11-01

Gait impairment in people with Multiple Sclerosis results from neurological impairment, muscle weakness and reduced range of motion. Restrictions in passive ankle range of motion can result in abnormal heel-to-toe progression (weight transfer) and inefficient gait patterns in people with Multiple Sclerosis. The purpose of this study was to determine the associations between gait impairment, heel-to-toe progression and ankle range of motion in people with Multiple Sclerosis. Twelve participants with Multiple Sclerosis and twelve healthy age-matched participants were assessed. Spatiotemporal parameters of gait and individual footprint data were used to investigate group differences. A pressure sensitive walkway was used to divide each footprint into three phases (contact, mid-stance, propulsive) and calculate the heel-to-toe progression during the stance phase of gait. Compared to healthy controls, people with Multiple Sclerosis spent relatively less time in contact phase (7.8% vs 25.1%) and more time in the mid stance phase of gait (57.3% vs 33.7%). Inter-limb differences were observed in people with Multiple Sclerosis between the affected and non-affected sides for contact (7.8% vs 15.3%) and mid stance (57.3% and 47.1%) phases. Differences in heel-to-toe progression remained significant after adjusting for walking speed and were correlated with walking distance and ankle range of motion. Impaired heel-to-toe progression was related to poor ankle range of motion in people with Multiple Sclerosis. Heel-to-toe progression provided a sensitive measure for assessing gait impairments that were not detectable using standard spatiotemporal gait parameters. Copyright © 2017 Elsevier Ltd. All rights reserved.

Compensating for intersegmental dynamics across the shoulder, elbow, and wrist joints during feedforward and feedback control.

PubMed

Maeda, Rodrigo S; Cluff, Tyler; Gribble, Paul L; Pruszynski, J Andrew

2017-10-01

Moving the arm is complicated by mechanical interactions that arise between limb segments. Such intersegmental dynamics cause torques applied at one joint to produce movement at multiple joints, and in turn, the only way to create single joint movement is by applying torques at multiple joints. We investigated whether the nervous system accounts for intersegmental limb dynamics across the shoulder, elbow, and wrist joints during self-initiated planar reaching and when countering external mechanical perturbations. Our first experiment tested whether the timing and amplitude of shoulder muscle activity account for interaction torques produced during single-joint elbow movements from different elbow initial orientations and over a range of movement speeds. We found that shoulder muscle activity reliably preceded movement onset and elbow agonist activity, and was scaled to compensate for the magnitude of interaction torques arising because of forearm rotation. Our second experiment tested whether elbow muscles compensate for interaction torques introduced by single-joint wrist movements. We found that elbow muscle activity preceded movement onset and wrist agonist muscle activity, and thus the nervous system predicted interaction torques arising because of hand rotation. Our third and fourth experiments tested whether shoulder muscles compensate for interaction torques introduced by different hand orientations during self-initiated elbow movements and to counter mechanical perturbations that caused pure elbow motion. We found that the nervous system predicted the amplitude and direction of interaction torques, appropriately scaling the amplitude of shoulder muscle activity during self-initiated elbow movements and rapid feedback control. Taken together, our results demonstrate that the nervous system robustly accounts for intersegmental dynamics and that the process is similar across the proximal to distal musculature of the arm as well as between feedforward (i.e., self-initiated) and feedback (i.e., reflexive) control. NEW & NOTEWORTHY Intersegmental dynamics complicate the mapping between applied joint torques and the resulting joint motions. We provide evidence that the nervous system robustly predicts these intersegmental limb dynamics across the shoulder, elbow, and wrist joints during reaching and when countering external perturbations. Copyright © 2017 the American Physiological Society.

Motion-form interactions beyond the motion integration level: evidence for interactions between orientation and optic flow signals.

PubMed

Pavan, Andrea; Marotti, Rosilari Bellacosa; Mather, George

2013-05-31

Motion and form encoding are closely coupled in the visual system. A number of physiological studies have shown that neurons in the striate and extrastriate cortex (e.g., V1 and MT) are selective for motion direction parallel to their preferred orientation, but some neurons also respond to motion orthogonal to their preferred spatial orientation. Recent psychophysical research (Mather, Pavan, Bellacosa, & Casco, 2012) has demonstrated that the strength of adaptation to two fields of transparently moving dots is modulated by simultaneously presented orientation signals, suggesting that the interaction occurs at the level of motion integrating receptive fields in the extrastriate cortex. In the present psychophysical study, we investigated whether motion-form interactions take place at a higher level of neural processing where optic flow components are extracted. In Experiment 1, we measured the duration of the motion aftereffect (MAE) generated by contracting or expanding dot fields in the presence of either radial (parallel) or concentric (orthogonal) counterphase pedestal gratings. To tap the stage at which optic flow is extracted, we measured the duration of the phantom MAE (Weisstein, Maguire, & Berbaum, 1977) in which we adapted and tested different parts of the visual field, with orientation signals presented either in the adapting (Experiment 2) or nonadapting (Experiments 3 and 4) sectors. Overall, the results showed that motion adaptation is suppressed most by orientation signals orthogonal to optic flow direction, suggesting that motion-form interactions also take place at the global motion level where optic flow is extracted.

Teaching Newton's Third Law of Motion in the Presence of Student Preconception

ERIC Educational Resources Information Center

Poon, C. H.

2006-01-01

The concept of interaction that underlies Newton's Laws of Motion is compared with the students' commonsense ideas of force and motion. An approach to teaching Newton's Third Law of Motion is suggested that focuses on refining the student's intuitive thinking on the nature of interaction.

Study of Wave-Particle Interactions for Whistler Mode Waves at Oblique Angles by Utilizing the Gyroaveraging Method

NASA Astrophysics Data System (ADS)

Hsieh, Yi-Kai; Omura, Yoshiharu

2017-10-01

We investigate the properties of whistler mode wave-particle interactions at oblique wave normal angles to the background magnetic field. We find that electromagnetic energy of waves at frequencies below half the electron cyclotron frequency can flow nearly parallel to the ambient magnetic field. We thereby confirm that the gyroaveraging method, which averages the cyclotron motion to the gyrocenter and reduces the simulation from two-dimensional to one-dimensional, is valid for oblique wave-particle interaction. Multiple resonances appear for oblique propagation but not for parallel propagation. We calculate the possible range of resonances with the first-order resonance condition as a function of electron kinetic energy and equatorial pitch angle. To reveal the physical process and the efficiency of electron acceleration by multiple resonances, we assume a simple uniform wave model with constant amplitude and frequency in space and time. We perform test particle simulations with electrons starting at specific equatorial pitch angles and kinetic energies. The simulation results show that multiple resonances contribute to acceleration and pitch angle scattering of energetic electrons. Especially, we find that electrons with energies of a few hundred keV can be accelerated efficiently to a few MeV through the n = 0 Landau resonance.

Trend-Centric Motion Visualization: Designing and Applying a New Strategy for Analyzing Scientific Motion Collections.

PubMed

Schroeder, David; Korsakov, Fedor; Knipe, Carissa Mai-Ping; Thorson, Lauren; Ellingson, Arin M; Nuckley, David; Carlis, John; Keefe, Daniel F

2014-12-01

In biomechanics studies, researchers collect, via experiments or simulations, datasets with hundreds or thousands of trials, each describing the same type of motion (e.g., a neck flexion-extension exercise) but under different conditions (e.g., different patients, different disease states, pre- and post-treatment). Analyzing similarities and differences across all of the trials in these collections is a major challenge. Visualizing a single trial at a time does not work, and the typical alternative of juxtaposing multiple trials in a single visual display leads to complex, difficult-to-interpret visualizations. We address this problem via a new strategy that organizes the analysis around motion trends rather than trials. This new strategy matches the cognitive approach that scientists would like to take when analyzing motion collections. We introduce several technical innovations making trend-centric motion visualization possible. First, an algorithm detects a motion collection's trends via time-dependent clustering. Second, a 2D graphical technique visualizes how trials leave and join trends. Third, a 3D graphical technique, using a median 3D motion plus a visual variance indicator, visualizes the biomechanics of the set of trials within each trend. These innovations are combined to create an interactive exploratory visualization tool, which we designed through an iterative process in collaboration with both domain scientists and a traditionally-trained graphic designer. We report on insights generated during this design process and demonstrate the tool's effectiveness via a validation study with synthetic data and feedback from expert musculoskeletal biomechanics researchers who used the tool to analyze the effects of disc degeneration on human spinal kinematics.

Bimorphic polymeric photomechanical actuator

NASA Technical Reports Server (NTRS)

Sarkisov, Sergey S. (Inventor); Curley, Michael J. (Inventor); Adamovsky, Grigory (Inventor); Sarkisov, Jr., Sergey S. (Inventor); Fields, Aisha B. (Inventor)

2006-01-01

A bimorphic polymeric photomechanical actuator, in one embodiment using polyvinylidene fluoride (PVDF) as a photosensitive body, transmitting light over fiber optic cables, and controlling the shape and pulse duration of the light pulse to control movement of the actuator. Multiple light beams are utilized to generate different ranges of motion for the actuator from a single photomechanical body and alternative designs use multiple light beams and multiple photomechanical bodies to provide controlled movement. Actuator movement using one or more ranges of motion is utilized to control motion to position an actuating element in three dimensional space.

Impaired global, and compensatory local, biological motion processing in people with high levels of autistic traits.

PubMed

van Boxtel, Jeroen J A; Lu, Hongjing

2013-01-01

People with Autism Spectrum Disorder (ASD) are hypothesized to have poor high-level processing but superior low-level processing, causing impaired social recognition, and a focus on non-social stimulus contingencies. Biological motion perception provides an ideal domain to investigate exactly how ASD modulates the interaction between low and high-level processing, because it involves multiple processing stages, and carries many important social cues. We investigated individual differences among typically developing observers in biological motion processing, and whether such individual differences associate with the number of autistic traits. In Experiment 1, we found that individuals with fewer autistic traits were automatically and involuntarily attracted to global biological motion information, whereas individuals with more autistic traits did not show this pre-attentional distraction. We employed an action adaptation paradigm in the second study to show that individuals with more autistic traits were able to compensate for deficits in global processing with an increased involvement in local processing. Our findings can be interpreted within a predictive coding framework, which characterizes the functional relationship between local and global processing stages, and explains how these stages contribute to the perceptual difficulties associated with ASD.

Impaired Global, and Compensatory Local, Biological Motion Processing in People with High Levels of Autistic Traits

PubMed Central

van Boxtel, Jeroen J. A.; Lu, Hongjing

2013-01-01

People with Autism Spectrum Disorder (ASD) are hypothesized to have poor high-level processing but superior low-level processing, causing impaired social recognition, and a focus on non-social stimulus contingencies. Biological motion perception provides an ideal domain to investigate exactly how ASD modulates the interaction between low and high-level processing, because it involves multiple processing stages, and carries many important social cues. We investigated individual differences among typically developing observers in biological motion processing, and whether such individual differences associate with the number of autistic traits. In Experiment 1, we found that individuals with fewer autistic traits were automatically and involuntarily attracted to global biological motion information, whereas individuals with more autistic traits did not show this pre-attentional distraction. We employed an action adaptation paradigm in the second study to show that individuals with more autistic traits were able to compensate for deficits in global processing with an increased involvement in local processing. Our findings can be interpreted within a predictive coding framework, which characterizes the functional relationship between local and global processing stages, and explains how these stages contribute to the perceptual difficulties associated with ASD. PMID:23630514

Motion-form interactions beyond the motion integration level: Evidence for interactions between orientation and optic flow signals

PubMed Central

Pavan, Andrea; Marotti, Rosilari Bellacosa; Mather, George

2013-01-01

Motion and form encoding are closely coupled in the visual system. A number of physiological studies have shown that neurons in the striate and extrastriate cortex (e.g., V1 and MT) are selective for motion direction parallel to their preferred orientation, but some neurons also respond to motion orthogonal to their preferred spatial orientation. Recent psychophysical research (Mather, Pavan, Bellacosa, & Casco, 2012) has demonstrated that the strength of adaptation to two fields of transparently moving dots is modulated by simultaneously presented orientation signals, suggesting that the interaction occurs at the level of motion integrating receptive fields in the extrastriate cortex. In the present psychophysical study, we investigated whether motion-form interactions take place at a higher level of neural processing where optic flow components are extracted. In Experiment 1, we measured the duration of the motion aftereffect (MAE) generated by contracting or expanding dot fields in the presence of either radial (parallel) or concentric (orthogonal) counterphase pedestal gratings. To tap the stage at which optic flow is extracted, we measured the duration of the phantom MAE (Weisstein, Maguire, & Berbaum, 1977) in which we adapted and tested different parts of the visual field, with orientation signals presented either in the adapting (Experiment 2) or nonadapting (Experiments 3 and 4) sectors. Overall, the results showed that motion adaptation is suppressed most by orientation signals orthogonal to optic flow direction, suggesting that motion-form interactions also take place at the global motion level where optic flow is extracted. PMID:23729767

Evaluating Remapped Physical Reach for Hand Interactions with Passive Haptics in Virtual Reality.

PubMed

Han, Dustin T; Suhail, Mohamed; Ragan, Eric D

2018-04-01

Virtual reality often uses motion tracking to incorporate physical hand movements into interaction techniques for selection and manipulation of virtual objects. To increase realism and allow direct hand interaction, real-world physical objects can be aligned with virtual objects to provide tactile feedback and physical grasping. However, unless a physical space is custom configured to match a specific virtual reality experience, the ability to perfectly match the physical and virtual objects is limited. Our research addresses this challenge by studying methods that allow one physical object to be mapped to multiple virtual objects that can exist at different virtual locations in an egocentric reference frame. We study two such techniques: one that introduces a static translational offset between the virtual and physical hand before a reaching action, and one that dynamically interpolates the position of the virtual hand during a reaching motion. We conducted two experiments to assess how the two methods affect reaching effectiveness, comfort, and ability to adapt to the remapping techniques when reaching for objects with different types of mismatches between physical and virtual locations. We also present a case study to demonstrate how the hand remapping techniques could be used in an immersive game application to support realistic hand interaction while optimizing usability. Overall, the translational technique performed better than the interpolated reach technique and was more robust for situations with larger mismatches between virtual and physical objects.

Dynamics, Conformational Entropy, and Frustration in Protein-Protein Interactions Involving an Intrinsically Disordered Protein Domain.

PubMed

Lindström, Ida; Dogan, Jakob

2018-05-18

Intrinsically disordered proteins (IDPs) are abundant in the eukaryotic proteome. However, little is known about the role of subnanosecond dynamics and the conformational entropy that it represents in protein-protein interactions involving IDPs. Using nuclear magnetic resonance side chain and backbone relaxation, stopped-flow kinetics, isothermal titration calorimetry, and computational studies, we have characterized the interaction between the globular TAZ1 domain of the CREB binding protein and the intrinsically disordered transactivation domain of STAT2 (TAD-STAT2). We show that the TAZ1/TAD-STAT2 complex retains considerable subnanosecond motions, with TAD-STAT2 undergoing only a partial disorder-to-order transition. We report here the first experimental determination of the conformational entropy change for both binding partners in an IDP binding interaction and find that the total change even exceeds in magnitude the binding enthalpy and is comparable to the contribution from the hydrophobic effect, demonstrating its importance in the binding energetics. Furthermore, we show that the conformational entropy change for TAZ1 is also instrumental in maintaining a biologically meaningful binding affinity. Strikingly, a spatial clustering of very high amplitude motions and a cluster of more rigid sites in the complex exist, which through computational studies we found to overlap with regions that experience energetic frustration and are less frustrated, respectively. Thus, the residual dynamics in the bound state could be necessary for faster dissociation, which is important for proteins that interact with multiple binding partners.

Elastic Cheerios effect: Self-assembly of cylinders on a soft solid

NASA Astrophysics Data System (ADS)

Chakrabarti, Aditi; Ryan, Louis; Chaudhury, Manoj K.; Mahadevan, L.

2015-12-01

A rigid cylinder placed on a soft gel deforms its surface. When multiple cylinders are placed on the surface, they interact with each other via the topography of the deformed gel which serves as an energy landscape; as they move, the landscape changes which in turn changes their interaction. We use a combination of experiments, simple scaling estimates and numerical simulations to study the self-assembly of cylinders in this elastic analog of the "Cheerios Effect", which describes capillary interactions on a fluid interface. Our results show that the effective two-body interaction can be well described by an exponential attraction potential as a result of which the dynamics also show an exponential behavior with respect to the separation distance. When many cylinders are placed on the gel, the cylinders cluster together if they are not too far apart; otherwise their motion gets elastically arrested.

Hybrid Co-Evolutionary Motion Planning via Visibility-Based Repair

NASA Technical Reports Server (NTRS)

Dozier, Gerry; McCullough, Shaun; Brown, Edward, Jr.; Homaifar, Abdollah; Bikdash, Mar-wan

1997-01-01

This paper introduces a hybrid co-evolutionary system for global motion planning within unstructured environments. This system combines the concept of co-evolutionary search along with a concept that we refer to as the visibility-based repair to form a hybrid which quickly transforms infeasible motions into feasible ones. Also, this system makes use of a novel representation scheme for the obstacles within an environment. Our hybrid evolutionary system differs from other evolutionary motion planners in that (1) more emphasis is placed on repairing infeasible motions to develop feasible motions rather than using simulated evolution exclusively as a means of discovering feasible motions, (2) a continuous map of the environment is used rather than a discretized map, and (3) it develops global motion plans for multiple mobile destinations by co-evolving populations of sub-global motion plans. In this paper, we demonstrate the effectiveness of this system by using it to solve two challenging motion planning problems where multiple targets try to move away from a point robot.

Motion interactive video games in home training for children with cerebral palsy: parents' perceptions.

PubMed

Sandlund, Marlene; Dock, Katarina; Häger, Charlotte K; Waterworth, Eva Lindh

2012-01-01

To explore parents' perceptions of using low-cost motion interactive video games as home training for their children with mild/moderate cerebral palsy. Semi-structured interviews were carried out with parents from 15 families after participation in an intervention where motion interactive games were used daily in home training for their child. A qualitative content analysis approach was applied. The parents' perception of the training was very positive. They expressed the view that motion interactive video games may promote positive experiences of physical training in rehabilitation, where the social aspects of gaming were especially valued. Further, the parents experienced less need to take on coaching while gaming stimulated independent training. However, there was a desire for more controlled and individualized games to better challenge the specific rehabilitative need of each child. Low-cost motion interactive games may provide increased motivation and social interaction to home training and promote independent training with reduced coaching efforts for the parents. In future designs of interactive games for rehabilitation purposes, it is important to preserve the motivational and social features of games while optimizing the individualized physical exercise.

Multimodal interaction for human-robot teams

NASA Astrophysics Data System (ADS)

Burke, Dustin; Schurr, Nathan; Ayers, Jeanine; Rousseau, Jeff; Fertitta, John; Carlin, Alan; Dumond, Danielle

2013-05-01

Unmanned ground vehicles have the potential for supporting small dismounted teams in mapping facilities, maintaining security in cleared buildings, and extending the team's reconnaissance and persistent surveillance capability. In order for such autonomous systems to integrate with the team, we must move beyond current interaction methods using heads-down teleoperation which require intensive human attention and affect the human operator's ability to maintain local situational awareness and ensure their own safety. This paper focuses on the design, development and demonstration of a multimodal interaction system that incorporates naturalistic human gestures, voice commands, and a tablet interface. By providing multiple, partially redundant interaction modes, our system degrades gracefully in complex environments and enables the human operator to robustly select the most suitable interaction method given the situational demands. For instance, the human can silently use arm and hand gestures for commanding a team of robots when it is important to maintain stealth. The tablet interface provides an overhead situational map allowing waypoint-based navigation for multiple ground robots in beyond-line-of-sight conditions. Using lightweight, wearable motion sensing hardware either worn comfortably beneath the operator's clothing or integrated within their uniform, our non-vision-based approach enables an accurate, continuous gesture recognition capability without line-of-sight constraints. To reduce the training necessary to operate the system, we designed the interactions around familiar arm and hand gestures.

Head Motion Modeling for Human Behavior Analysis in Dyadic Interaction

PubMed Central

Xiao, Bo; Georgiou, Panayiotis; Baucom, Brian; Narayanan, Shrikanth S.

2015-01-01

This paper presents a computational study of head motion in human interaction, notably of its role in conveying interlocutors’ behavioral characteristics. Head motion is physically complex and carries rich information; current modeling approaches based on visual signals, however, are still limited in their ability to adequately capture these important properties. Guided by the methodology of kinesics, we propose a data driven approach to identify typical head motion patterns. The approach follows the steps of first segmenting motion events, then parametrically representing the motion by linear predictive features, and finally generalizing the motion types using Gaussian mixture models. The proposed approach is experimentally validated using video recordings of communication sessions from real couples involved in a couples therapy study. In particular we use the head motion model to classify binarized expert judgments of the interactants’ specific behavioral characteristics where entrainment in head motion is hypothesized to play a role: Acceptance, Blame, Positive, and Negative behavior. We achieve accuracies in the range of 60% to 70% for the various experimental settings and conditions. In addition, we describe a measure of motion similarity between the interaction partners based on the proposed model. We show that the relative change of head motion similarity during the interaction significantly correlates with the expert judgments of the interactants’ behavioral characteristics. These findings demonstrate the effectiveness of the proposed head motion model, and underscore the promise of analyzing human behavioral characteristics through signal processing methods. PMID:26557047

Ubiquitin immobilized on mesoporous MCM41 silica surfaces - Analysis by solid-state NMR with biophysical and surface characterization.

PubMed

Adiram-Filiba, Nurit; Schremer, Avital; Ohaion, Eli; Nadav-Tsubery, Merav; Lublin-Tennenbaum, Tammi; Keinan-Adamsky, Keren; Goobes, Gil

2017-05-31

Deriving the conformation of adsorbed proteins is important in the assessment of their functional activity when immobilized. This has particularly important bearings on the design of contemporary and new encapsulated enzyme-based drugs, biosensors, and other bioanalytical devices. Solid-state nuclear magnetic resonance (NMR) measurements can expand our molecular view of proteins in this state and of the molecular interactions governing protein immobilization on popular biocompatible surfaces such as silica. Here, the authors study the immobilization of ubiquitin on the mesoporous silica MCM41 by NMR and other techniques. Protein molecules are shown to bind efficiently at pH 5 through electrostatic interactions to individual MCM41 particles, causing their agglutination. The strong attraction of ubiquitin to MCM41 surface is given molecular context through evidence of proximity of basic, carbonyl and polar groups on the protein to groups on the silica surface using NMR measurements. The immobilized protein exhibits broad peaks in two-dimensional 13 C dipolar-assisted rotational resonance spectra, an indication of structural multiplicity. At the same time, cross-peaks related to Tyr and Phe sidechains are missing due to motional averaging. Overall, the favorable adsorption of ubiquitin to MCM41 is accompanied by conformational heterogeneity and by a major loss of motional degrees of freedom as inferred from the marked entropy decrease. Nevertheless, local motions of the aromatic rings are retained in the immobilized state.

KALI - An environment for the programming and control of cooperative manipulators

NASA Technical Reports Server (NTRS)

Hayward, Vincent; Hayati, Samad

1988-01-01

A design description is given of a controller for cooperative robots. The background and motivation for multiple arm control are discussed. A set of programming primitives which permit a programmer to specify cooperative tasks are described. Motion primitives specify asynchronous motions, master/slave motions, and cooperative motions. In the context of cooperative robots, trajectory generation issues are discussed and the authors' implementation briefly described. The relations between programming and control in the case of multiple robots are examined. The allocation of various tasks among a multiprocessor computer is described.

MotionFlow: Visual Abstraction and Aggregation of Sequential Patterns in Human Motion Tracking Data.

PubMed

Jang, Sujin; Elmqvist, Niklas; Ramani, Karthik

2016-01-01

Pattern analysis of human motions, which is useful in many research areas, requires understanding and comparison of different styles of motion patterns. However, working with human motion tracking data to support such analysis poses great challenges. In this paper, we propose MotionFlow, a visual analytics system that provides an effective overview of various motion patterns based on an interactive flow visualization. This visualization formulates a motion sequence as transitions between static poses, and aggregates these sequences into a tree diagram to construct a set of motion patterns. The system also allows the users to directly reflect the context of data and their perception of pose similarities in generating representative pose states. We provide local and global controls over the partition-based clustering process. To support the users in organizing unstructured motion data into pattern groups, we designed a set of interactions that enables searching for similar motion sequences from the data, detailed exploration of data subsets, and creating and modifying the group of motion patterns. To evaluate the usability of MotionFlow, we conducted a user study with six researchers with expertise in gesture-based interaction design. They used MotionFlow to explore and organize unstructured motion tracking data. Results show that the researchers were able to easily learn how to use MotionFlow, and the system effectively supported their pattern analysis activities, including leveraging their perception and domain knowledge.

A linear complementarity method for the solution of vertical vehicle-track interaction

NASA Astrophysics Data System (ADS)

Zhang, Jian; Gao, Qiang; Wu, Feng; Zhong, Wan-Xie

2018-02-01

A new method is proposed for the solution of the vertical vehicle-track interaction including a separation between wheel and rail. The vehicle is modelled as a multi-body system using rigid bodies, and the track is treated as a three-layer beam model in which the rail is considered as an Euler-Bernoulli beam and both the sleepers and the ballast are represented by lumped masses. A linear complementarity formulation is directly established using a combination of the wheel-rail normal contact condition and the generalised-α method. This linear complementarity problem is solved using the Lemke algorithm, and the wheel-rail contact force can be obtained. Then the dynamic responses of the vehicle and the track are solved without iteration based on the generalised-α method. The same equations of motion for the vehicle and track are adopted at the different wheel-rail contact situations. This method can remove some restrictions, that is, time-dependent mass, damping and stiffness matrices of the coupled system, multiple equations of motion for the different contact situations and the effect of the contact stiffness. Numerical results demonstrate that the proposed method is effective for simulating the vehicle-track interaction including a separation between wheel and rail.

Information Transfer Capacity of Articulators in American Sign Language.

PubMed

Malaia, Evie; Borneman, Joshua D; Wilbur, Ronnie B

2018-03-01

The ability to convey information is a fundamental property of communicative signals. For sign languages, which are overtly produced with multiple, completely visible articulators, the question arises as to how the various channels co-ordinate and interact with each other. We analyze motion capture data of American Sign Language (ASL) narratives, and show that the capacity of information throughput, mathematically defined, is highest on the dominant hand (DH). We further demonstrate that information transfer capacity is also significant for the non-dominant hand (NDH), and the head channel too, as compared to control channels (ankles). We discuss both redundancy and independence in articulator motion in sign language, and argue that the NDH and the head articulators contribute to the overall information transfer capacity, indicating that they are neither completely redundant to, nor completely independent of, the DH.

Sensor fusion IV: Control paradigms and data structures; Proceedings of the Meeting, Boston, MA, Nov. 12-15, 1991

NASA Technical Reports Server (NTRS)

Schenker, Paul S. (Editor)

1992-01-01

Various papers on control paradigms and data structures in sensor fusion are presented. The general topics addressed include: decision models and computational methods, sensor modeling and data representation, active sensing strategies, geometric planning and visualization, task-driven sensing, motion analysis, models motivated biology and psychology, decentralized detection and distributed decision, data fusion architectures, robust estimation of shapes and features, application and implementation. Some of the individual subjects considered are: the Firefly experiment on neural networks for distributed sensor data fusion, manifold traversing as a model for learning control of autonomous robots, choice of coordinate systems for multiple sensor fusion, continuous motion using task-directed stereo vision, interactive and cooperative sensing and control for advanced teleoperation, knowledge-based imaging for terrain analysis, physical and digital simulations for IVA robotics.

Vibration control of a cluster of buildings through the Vibrating Barrier

NASA Astrophysics Data System (ADS)

Tombari, A.; Garcia Espinosa, M.; Alexander, N. A.; Cacciola, P.

2018-02-01

A novel device, called Vibrating Barrier (ViBa), that aims to reduce the vibrations of adjacent structures subjected to ground motion waves has been recently proposed. The ViBa is a structure buried in the soil and detached from surrounding buildings that is able to absorb a significant portion of the dynamic energy arising from the ground motion. The working principle exploits the dynamic interaction among vibrating structures due to the propagation of waves through the soil, namely the structure-soil-structure interaction. In this paper the efficiency of the ViBa is investigated to control the vibrations of a cluster of buildings. To this aim, a discrete model of structures-site interaction involving multiple buildings and the ViBa is developed where the effects of the soil on the structures, i.e. the soil-structure interaction (SSI), the structure-soil-structure interaction (SSSI) as well as the ViBa-soil-structures interaction are taken into account by means of linear elastic springs. Closed-form solutions are derived to design the ViBa in the case of harmonic excitation from the analysis of the discrete model. Advanced finite element numerical simulations are performed in order to assess the efficiency of the ViBa for protecting more than a single building. Parametric studies are also conducted to identify beneficial/adverse effects in the use of the proposed vibration control strategy to protect cluster of buildings. Finally, experimental shake table tests are performed to a prototype of a cluster of two buildings protected by the ViBa device for validating the proposed numerical models.

A video, text, and speech-driven realistic 3-d virtual head for human-machine interface.

PubMed

Yu, Jun; Wang, Zeng-Fu

2015-05-01

A multiple inputs-driven realistic facial animation system based on 3-D virtual head for human-machine interface is proposed. The system can be driven independently by video, text, and speech, thus can interact with humans through diverse interfaces. The combination of parameterized model and muscular model is used to obtain a tradeoff between computational efficiency and high realism of 3-D facial animation. The online appearance model is used to track 3-D facial motion from video in the framework of particle filtering, and multiple measurements, i.e., pixel color value of input image and Gabor wavelet coefficient of illumination ratio image, are infused to reduce the influence of lighting and person dependence for the construction of online appearance model. The tri-phone model is used to reduce the computational consumption of visual co-articulation in speech synchronized viseme synthesis without sacrificing any performance. The objective and subjective experiments show that the system is suitable for human-machine interaction.

Detecting abandoned objects using interacting multiple models

NASA Astrophysics Data System (ADS)

Becker, Stefan; Münch, David; Kieritz, Hilke; Hübner, Wolfgang; Arens, Michael

2015-10-01

In recent years, the wide use of video surveillance systems has caused an enormous increase in the amount of data that has to be stored, monitored, and processed. As a consequence, it is crucial to support human operators with automated surveillance applications. Towards this end an intelligent video analysis module for real-time alerting in case of abandoned objects in public spaces is proposed. The overall processing pipeline consists of two major parts. First, person motion is modeled using an Interacting Multiple Model (IMM) filter. The IMM filter estimates the state of a person according to a finite-state, discrete-time Markov chain. Second, the location of persons that stay at a fixed position defines a region of interest, in which a nonparametric background model with dynamic per-pixel state variables identifies abandoned objects. In case of a detected abandoned object, an alarm event is triggered. The effectiveness of the proposed system is evaluated on the PETS 2006 dataset and the i-Lids dataset, both reflecting prototypical surveillance scenarios.

Multiradar tracking for theater missile defense

NASA Astrophysics Data System (ADS)

Sviestins, Egils

1995-09-01

A prototype system for tracking tactical ballistic missiles using multiple radars has been developed. The tracking is based on measurement level fusion (`true' multi-radar) tracking. Strobes from passive sensors can also be used. We describe various features of the system with some emphasis on the filtering technique. This is based on the Interacting Multiple Model framework where the states are Free Flight, Drag, Boost, and Auxiliary. Measurement error modeling includes the signal to noise ratio dependence; outliers and miscorrelations are handled in the same way. The launch point is calculated within one minute from the detection of the missile. The impact point, and its uncertainty region, is calculated continually by extrapolating the track state vector using the equations of planetary motion.

Cognitive Rehabilitation in Bilateral Vestibular Patients: A Computational Perspective.

PubMed

Ellis, Andrew W; Schöne, Corina G; Vibert, Dominique; Caversaccio, Marco D; Mast, Fred W

2018-01-01

There is evidence that vestibular sensory processing affects, and is affected by, higher cognitive processes. This is highly relevant from a clinical perspective, where there is evidence for cognitive impairments in patients with peripheral vestibular deficits. The vestibular system performs complex probabilistic computations, and we claim that understanding these is important for investigating interactions between vestibular processing and cognition. Furthermore, this will aid our understanding of patients' self-motion perception and will provide useful information for clinical interventions. We propose that cognitive training is a promising way to alleviate the debilitating symptoms of patients with complete bilateral vestibular loss (BVP), who often fail to show improvement when relying solely on conventional treatment methods. We present a probabilistic model capable of processing vestibular sensory data during both passive and active self-motion. Crucially, in our model, knowledge from multiple sources, including higher-level cognition, can be used to predict head motion. This is the entry point for cognitive interventions. Despite the loss of sensory input, the processing circuitry in BVP patients is still intact, and they can still perceive self-motion when the movement is self-generated. We provide computer simulations illustrating self-motion perception of BVP patients. Cognitive training may lead to more accurate and confident predictions, which result in decreased weighting of sensory input, and thus improved self-motion perception. Using our model, we show the possible impact of cognitive interventions to help vestibular rehabilitation in patients with BVP.

Emergence of collective motion in bacterial suspensions

NASA Astrophysics Data System (ADS)

Liu, Song

It is well known that bacterial suspensions will exhibit collective motion at high concentrations, in which both steric and hydrodynamic interactions play important roles. We aim to investigate whether steric and hydrodynamic interactions are of equal importance to the emergence of collective motion. Here we will present our efforts to experimentally tune the relative strength of these interactions in bacterial suspensions. Our preliminary results suggest that the transition to collective motion may depend on the interplay between steric and hydrodynamic interactions. Mailing address: Room 306 Science Centre North Block, The Chinese University of Hong Kong, Shatin, N.T. Hong Kong SAR. Phone: +852-3943-6354. Fax: +852-2603-5204. E-mail: songliuphy@gmail.com.

How Many Objects are You Worth? Quantification of the Self-Motion Load on Multiple Object Tracking

PubMed Central

Thomas, Laura E.; Seiffert, Adriane E.

2011-01-01

Perhaps walking and chewing gum is effortless, but walking and tracking moving objects is not. Multiple object tracking is impaired by walking from one location to another, suggesting that updating location of the self puts demands on object tracking processes. Here, we quantified the cost of self-motion in terms of the tracking load. Participants in a virtual environment tracked a variable number of targets (1–5) among distractors while either staying in one place or moving along a path that was similar to the objects’ motion. At the end of each trial, participants decided whether a probed dot was a target or distractor. As in our previous work, self-motion significantly impaired performance in tracking multiple targets. Quantifying tracking capacity for each individual under move versus stay conditions further revealed that self-motion during tracking produced a cost to capacity of about 0.8 (±0.2) objects. Tracking your own motion is worth about one object, suggesting that updating the location of the self is similar, but perhaps slightly easier, than updating locations of objects. PMID:21991259

Trend-Centric Motion Visualization: Designing and Applying a new Strategy for Analyzing Scientific Motion Collections

PubMed Central

Schroeder, David; Korsakov, Fedor; Knipe, Carissa Mai-Ping; Thorson, Lauren; Ellingson, Arin M.; Nuckley, David; Carlis, John; Keefe, Daniel F

2017-01-01

In biomechanics studies, researchers collect, via experiments or simulations, datasets with hundreds or thousands of trials, each describing the same type of motion (e.g., a neck flexion-extension exercise) but under different conditions (e.g., different patients, different disease states, pre- and post-treatment). Analyzing similarities and differences across all of the trials in these collections is a major challenge. Visualizing a single trial at a time does not work, and the typical alternative of juxtaposing multiple trials in a single visual display leads to complex, difficult-to-interpret visualizations. We address this problem via a new strategy that organizes the analysis around motion trends rather than trials. This new strategy matches the cognitive approach that scientists would like to take when analyzing motion collections. We introduce several technical innovations making trend-centric motion visualization possible. First, an algorithm detects a motion collection’s trends via time-dependent clustering. Second, a 2D graphical technique visualizes how trials leave and join trends. Third, a 3D graphical technique, using a median 3D motion plus a visual variance indicator, visualizes the biomechanics of the set of trials within each trend. These innovations are combined to create an interactive exploratory visualization tool, which we designed through an iterative process in collaboration with both domain scientists and a traditionally-trained graphic designer. We report on insights generated during this design process and demonstrate the tool’s effectiveness via a validation study with synthetic data and feedback from expert musculoskeletal biomechanics researchers who used the tool to analyze the effects of disc degeneration on human spinal kinematics. PMID:26356978

Scientific Visualization of Radio Astronomy Data using Gesture Interaction

NASA Astrophysics Data System (ADS)

Mulumba, P.; Gain, J.; Marais, P.; Woudt, P.

2015-09-01

MeerKAT in South Africa (Meer = More Karoo Array Telescope) will require software to help visualize, interpret and interact with multidimensional data. While visualization of multi-dimensional data is a well explored topic, little work has been published on the design of intuitive interfaces to such systems. More specifically, the use of non-traditional interfaces (such as motion tracking and multi-touch) has not been widely investigated within the context of visualizing astronomy data. We hypothesize that a natural user interface would allow for easier data exploration which would in turn lead to certain kinds of visualizations (volumetric, multidimensional). To this end, we have developed a multi-platform scientific visualization system for FITS spectral data cubes using VTK (Visualization Toolkit) and a natural user interface to explore the interaction between a gesture input device and multidimensional data space. Our system supports visual transformations (translation, rotation and scaling) as well as sub-volume extraction and arbitrary slicing of 3D volumetric data. These tasks were implemented across three prototypes aimed at exploring different interaction strategies: standard (mouse/keyboard) interaction, volumetric gesture tracking (Leap Motion controller) and multi-touch interaction (multi-touch monitor). A Heuristic Evaluation revealed that the volumetric gesture tracking prototype shows great promise for interfacing with the depth component (z-axis) of 3D volumetric space across multiple transformations. However, this is limited by users needing to remember the required gestures. In comparison, the touch-based gesture navigation is typically more familiar to users as these gestures were engineered from standard multi-touch actions. Future work will address a complete usability test to evaluate and compare the different interaction modalities against the different visualization tasks.

A many-body states picture of electronic friction: The case of multiple orbitals and multiple electronic states

NASA Astrophysics Data System (ADS)

Dou, Wenjie; Subotnik, Joseph E.

2016-08-01

We present a very general form of electronic friction as present when a molecule with multiple orbitals hybridizes with a metal electrode. To develop this picture of friction, we embed the quantum-classical Liouville equation (QCLE) within a classical master equation (CME). Thus, this article extends our previous work analyzing the case of one electronic level, as we may now treat the case of multiple levels and many electronic molecular states. We show that, in the adiabatic limit, where electron transitions are much faster than nuclear motion, the QCLE-CME reduces to a Fokker-Planck equation, such that nuclei feel an average force as well as friction and a random force—as caused by their interaction with the metallic electrons. Finally, we show numerically and analytically that our frictional results agree with other published results calculated using non-equilibrium Green's functions. Numerical recipes for solving this QCLE-CME will be provided in a subsequent paper.

A many-body states picture of electronic friction: The case of multiple orbitals and multiple electronic states

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

Dou, Wenjie; Subotnik, Joseph E.

We present a very general form of electronic friction as present when a molecule with multiple orbitals hybridizes with a metal electrode. To develop this picture of friction, we embed the quantum-classical Liouville equation (QCLE) within a classical master equation (CME). Thus, this article extends our previous work analyzing the case of one electronic level, as we may now treat the case of multiple levels and many electronic molecular states. We show that, in the adiabatic limit, where electron transitions are much faster than nuclear motion, the QCLE-CME reduces to a Fokker-Planck equation, such that nuclei feel an average forcemore » as well as friction and a random force—as caused by their interaction with the metallic electrons. Finally, we show numerically and analytically that our frictional results agree with other published results calculated using non-equilibrium Green’s functions. Numerical recipes for solving this QCLE-CME will be provided in a subsequent paper.« less

iMODS: internal coordinates normal mode analysis server.

PubMed

López-Blanco, José Ramón; Aliaga, José I; Quintana-Ortí, Enrique S; Chacón, Pablo

2014-07-01

Normal mode analysis (NMA) in internal (dihedral) coordinates naturally reproduces the collective functional motions of biological macromolecules. iMODS facilitates the exploration of such modes and generates feasible transition pathways between two homologous structures, even with large macromolecules. The distinctive internal coordinate formulation improves the efficiency of NMA and extends its applicability while implicitly maintaining stereochemistry. Vibrational analysis, motion animations and morphing trajectories can be easily carried out at different resolution scales almost interactively. The server is versatile; non-specialists can rapidly characterize potential conformational changes, whereas advanced users can customize the model resolution with multiple coarse-grained atomic representations and elastic network potentials. iMODS supports advanced visualization capabilities for illustrating collective motions, including an improved affine-model-based arrow representation of domain dynamics. The generated all-heavy-atoms conformations can be used to introduce flexibility for more advanced modeling or sampling strategies. The server is free and open to all users with no login requirement at http://imods.chaconlab.org. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

ATHLETE's Feet: Mu1ti-Resolution Planning for a Hexapod Robot

NASA Technical Reports Server (NTRS)

Smith, Tristan B.; Barreiro, Javier; Smith, David E.; SunSpiral, Vytas; Chavez-Clemente, Daniel

2008-01-01

ATHLETE is a large six-legged tele-operated robot. Each foot is a wheel; travel can be achieved by walking, rolling, or some combination of the two. Operators control ATHLETE by selecting parameterized commands from a command dictionary. While rolling can be done efficiently with a single command, any motion involving steps is cumbersome - walking a few meters through difficult terrain can take hours. Our goal is to improve operator efficiency by automatically generating sequences of motion commands. There is increasing uncertainty regarding ATHLETE s actual configuration over time and decreasing quality of terrain data farther away from the current position. This, combined with the complexity that results from 36 degrees of kinematic freedom, led to an architecture that interleaves planning and execution at multiple levels, ranging from traditional configuration space motion planning algorithms for immediate moves to higher level task and path planning algorithms for overall travel. The modularity of the architecture also simplifies the development process and allows the operator to interact with and control the system at varying levels of autonomy depending on terrain and need.

Control strategies for robots in contact

NASA Astrophysics Data System (ADS)

Park, Jaeheung

In the field of robotics, there is a growing need to provide robots with the ability to interact with complex and unstructured environments. Operations in such environments pose significant challenges in terms of sensing, planning, and control. In particular, it is critical to design control algorithms that account for the dynamics of the robot and environment at multiple contacts. The work in this thesis focuses on the development of a control framework that addresses these issues. The approaches are based on the operational space control framework and estimation methods. By accounting for the dynamics of the robot and environment, modular and systematic methods are developed for robots interacting with the environment at multiple locations. The proposed force control approach demonstrates high performance in the presence of uncertainties. Building on this basic capability, new control algorithms have been developed for haptic teleoperation, multi-contact interaction with the environment, and whole body motion of non-fixed based robots. These control strategies have been experimentally validated through simulations and implementations on physical robots. The results demonstrate the effectiveness of the new control structure and its robustness to uncertainties. The contact control strategies presented in this thesis are expected to contribute to the needs in advanced controller design for humanoid and other complex robots interacting with their environments.

Sub-block motion derivation for merge mode in HEVC

NASA Astrophysics Data System (ADS)

Chien, Wei-Jung; Chen, Ying; Chen, Jianle; Zhang, Li; Karczewicz, Marta; Li, Xiang

2016-09-01

The new state-of-the-art video coding standard, H.265/HEVC, has been finalized in 2013 and it achieves roughly 50% bit rate saving compared to its predecessor, H.264/MPEG-4 AVC. In this paper, two additional merge candidates, advanced temporal motion vector predictor and spatial-temporal motion vector predictor, are developed to improve motion information prediction scheme under the HEVC structure. The proposed method allows each Prediction Unit (PU) to fetch multiple sets of motion information from multiple blocks smaller than the current PU. By splitting a large PU into sub-PUs and filling motion information for all the sub-PUs of the large PU, signaling cost of motion information could be reduced. This paper describes above-mentioned techniques in detail and evaluates their coding performance benefits based on the common test condition during HEVC development. Simulation results show that 2.4% performance improvement over HEVC can be achieved.

FlyCap: Markerless Motion Capture Using Multiple Autonomous Flying Cameras.

PubMed

Xu, Lan; Liu, Yebin; Cheng, Wei; Guo, Kaiwen; Zhou, Guyue; Dai, Qionghai; Fang, Lu

2017-07-18

Aiming at automatic, convenient and non-instrusive motion capture, this paper presents a new generation markerless motion capture technique, the FlyCap system, to capture surface motions of moving characters using multiple autonomous flying cameras (autonomous unmanned aerial vehicles(UAVs) each integrated with an RGBD video camera). During data capture, three cooperative flying cameras automatically track and follow the moving target who performs large-scale motions in a wide space. We propose a novel non-rigid surface registration method to track and fuse the depth of the three flying cameras for surface motion tracking of the moving target, and simultaneously calculate the pose of each flying camera. We leverage the using of visual-odometry information provided by the UAV platform, and formulate the surface tracking problem in a non-linear objective function that can be linearized and effectively minimized through a Gaussian-Newton method. Quantitative and qualitative experimental results demonstrate the plausible surface and motion reconstruction results.

Jumbo tornado outbreak of 3 April 1974

NASA Technical Reports Server (NTRS)

Fujita, T. T.

1974-01-01

General meteorological data concerning the Jumbo tornado outbreak are presented. In terms of tornado number and total path mileage, it was more extensive than all known outbreaks. Most of the intense tornadoes avoided the large cities, however. Turn information is analyzed in detail. Left-turn tornadoes were more intense than right-turn tornadoes. Many important phenomena were observed, such as multiple suction vortices, family tornadoes, and cousin tornadoes spawned from interacting tornado cyclones. Aerial survey data will aid greatly in the solution of various scales of rotating motions, leading to improved prediction and warning of tornadoes.

Plasticity of ductile metallic glasses: a self-organized critical state.

PubMed

Sun, B A; Yu, H B; Jiao, W; Bai, H Y; Zhao, D Q; Wang, W H

2010-07-16

We report a close correlation between the dynamic behavior of serrated flow and the plasticity in metallic glasses (MGs) and show that the plastic deformation of ductile MGs can evolve into a self-organized critical state characterized by the power-law distribution of shear avalanches. A stick-slip model considering the interaction of multiple shear bands is presented to reveal complex scale-free intermittent shear-band motions in ductile MGs and quantitatively reproduce the experimental observations. Our studies have implications for understanding the precise plastic deformation mechanism of MGs.

Biomechanical Constraints Underlying Motor Primitives Derived from the Musculoskeletal Anatomy of the Human Arm.

PubMed

Gritsenko, Valeriya; Hardesty, Russell L; Boots, Mathew T; Yakovenko, Sergiy

2016-01-01

Neural control of movement can only be realized though the interaction between the mechanical properties of the limb and the environment. Thus, a fundamental question is whether anatomy has evolved to simplify neural control by shaping these interactions in a beneficial way. This inductive data-driven study analyzed the patterns of muscle actions across multiple joints using the musculoskeletal model of the human upper limb. This model was used to calculate muscle lengths across the full range of motion of the arm and examined the correlations between these values between all pairs of muscles. Musculoskeletal coupling was quantified using hierarchical clustering analysis. Muscle lengths between multiple pairs of muscles across multiple postures were highly correlated. These correlations broadly formed two proximal and distal groups, where proximal muscles of the arm were correlated with each other and distal muscles of the arm and hand were correlated with each other, but not between groups. Using hierarchical clustering, between 11 and 14 reliable muscle groups were identified. This shows that musculoskeletal anatomy does indeed shape the mechanical interactions by grouping muscles into functional clusters that generally match the functional repertoire of the human arm. Together, these results support the idea that the structure of the musculoskeletal system is tuned to solve movement complexity problem by reducing the dimensionality of available solutions.

Assessing the Validity of Multiple-Choice Questions in Measuring Fourth Graders' Ability to Interpret Graphs about Motion and Temperature

ERIC Educational Resources Information Center

Dulger, Mehmet; Deniz, Hasan

2017-01-01

The purpose of this paper is to assess the validity of multiple-choice questions in measuring fourth grade students' ability to interpret graphs related to physical science topics such as motion and temperature. We administered a test including 6 multiple-choice questions to 28 fourth grade students. Students were asked to explain their thinking…

An integrated framework for detecting suspicious behaviors in video surveillance

NASA Astrophysics Data System (ADS)

Zin, Thi Thi; Tin, Pyke; Hama, Hiromitsu; Toriu, Takashi

2014-03-01

In this paper, we propose an integrated framework for detecting suspicious behaviors in video surveillance systems which are established in public places such as railway stations, airports, shopping malls and etc. Especially, people loitering in suspicion, unattended objects left behind and exchanging suspicious objects between persons are common security concerns in airports and other transit scenarios. These involve understanding scene/event, analyzing human movements, recognizing controllable objects, and observing the effect of the human movement on those objects. In the proposed framework, multiple background modeling technique, high level motion feature extraction method and embedded Markov chain models are integrated for detecting suspicious behaviors in real time video surveillance systems. Specifically, the proposed framework employs probability based multiple backgrounds modeling technique to detect moving objects. Then the velocity and distance measures are computed as the high level motion features of the interests. By using an integration of the computed features and the first passage time probabilities of the embedded Markov chain, the suspicious behaviors in video surveillance are analyzed for detecting loitering persons, objects left behind and human interactions such as fighting. The proposed framework has been tested by using standard public datasets and our own video surveillance scenarios.

Multisensory effects on somatosensation: a trimodal visuo-vestibular-tactile interaction

PubMed Central

Kaliuzhna, Mariia; Ferrè, Elisa Raffaella; Herbelin, Bruno; Blanke, Olaf; Haggard, Patrick

2016-01-01

Vestibular information about self-motion is combined with other sensory signals. Previous research described both visuo-vestibular and vestibular-tactile bilateral interactions, but the simultaneous interaction between all three sensory modalities has not been explored. Here we exploit a previously reported visuo-vestibular integration to investigate multisensory effects on tactile sensitivity in humans. Tactile sensitivity was measured during passive whole body rotations alone or in conjunction with optic flow, creating either purely vestibular or visuo-vestibular sensations of self-motion. Our results demonstrate that tactile sensitivity is modulated by perceived self-motion, as provided by a combined visuo-vestibular percept, and not by the visual and vestibular cues independently. We propose a hierarchical multisensory interaction that underpins somatosensory modulation: visual and vestibular cues are first combined to produce a multisensory self-motion percept. Somatosensory processing is then enhanced according to the degree of perceived self-motion. PMID:27198907

A multiple fault rupture model of the November 13 2016, M 7.8 Kaikoura earthquake, New Zealand

NASA Astrophysics Data System (ADS)

Benites, R. A.; Francois-Holden, C.; Langridge, R. M.; Kaneko, Y.; Fry, B.; Kaiser, A. E.; Caldwell, T. G.

2017-12-01

The rupture-history of the November 13 2016 MW7.8 Kaikoura earthquake recorded by near- and intermediate-field strong-motion seismometers and 2 high-rate GPS stations reveals a complex cascade of multiple crustal fault rupture. In spite of such complexity, we show that the rupture history of each fault is well approximated by simple kinematic model with uniform slip and rupture velocity. Using 9 faults embedded in a crustal layer 19 km thick, each with a prescribed slip vector and rupture velocity, this model accurately reproduces the displacement waveforms recorded at the near-field strong-motion and GPS stations. This model includes the `Papatea Fault' with a mixed thrust and strike-slip mechanism based on in-situ geological observations with up to 8 m of uplift observed. Although the kinematic model fits the ground-motion at the nearest strong station, it doesn not reproduce the one sided nature of the static deformation field observed geodetically. This suggests a dislocation based approach does not completely capture the mechanical response of the Papatea Fault. The fault system as a whole extends for approximately 150 km along the eastern side of the Marlborough fault system in the South Island of New Zealand. The total duration of the rupture was 74 seconds. The timing and location of each fault's rupture suggests fault interaction and triggering resulting in a northward cascade crustal ruptures. Our model does not require rupture of the underlying subduction interface to explain the data.

Precision manipulation with a dextrous robot hand

NASA Astrophysics Data System (ADS)

Michelman, Paul

1994-01-01

In this thesis, we discuss a framework for describing and synthesizing precision manipulation tasks with a robot hand. Precision manipulations are those in which the motions of grasped objects are caused by finger motions alone (as distinct from arm or wrist motion). Experiments demonstrating the capabilities of the Utah-MIT hand are presented. This work begins by examining current research on biological motor control to raise a number of questions. For example, is the control centralized and organized by a central processor? Or is the control distributed throughout the nervous system? Motor control research on manipulation has focused on developing classifications of hand motions, concentrating solely on finger motions, while neglecting grasp stability and interaction forces that occur in manipulation. In addition, these taxonomies have not been explicitly functional. This thesis defines and analyzes a basic set of manipulation strategies that includes both position and force trajectories. The fundamental purposes of the manipulations are: (1) rectilinear and rotational motion of grasped objects of different geometries; and (2) the application of forces and moments against the environment by the grasped objects. First, task partitioning is described to allocate the fingers their roles in the task. Second, for each strategy, the mechanics and workspace of the tasks are analyzed geometrically to determine the gross finger trajectories required to achieve the tasks. Techniques illustrating the combination of simple manipulations into complex, multiple degree-of-freedom tasks are presented. There is a discussion of several tasks that use multiple elementary strategies. The tasks described are removing the top of a childproof medicine bottle, putting the top back on, rotating and regrasping a block and a cylinder within the grasp. Finally, experimental results are presented. The experimental setup at Columbia University's Center for Research in Intelligent Systems and experiments with a Utah-MIT hand is discussed. First, the overall system design is described. Two hybrid position/force controllers were designed and built. After a discussion of the entire system, experimental results are presented describing each of the basic manipulation and complex manipulation strategies.

The Lattice Dynamics of Colloidal Crystals.

NASA Astrophysics Data System (ADS)

Hurd, Alan James

Colloidal crystals are ordered arrays of highly charged microspheres in water that exhibit spectacular optical diffraction effects by virtue of a large lattice parameter. The microspheres perform Brownian motion that is influenced by the interparticle and fluid forces. The purpose of this study was to understand the nature of the collective motions in colloidal crystals in terms of classical lattice dynamics. In the theoretical analysis, the particle displacements due to Brownian motion were formally decomposed into phonon -like lattice disturbances analogous to the phonons in atomic and molecular solids except that they are heavily damped. The analysis was based on a harmonic solid model with special attention paid to the hydrodynamic interaction between particles. A hydrodynamic model using the Oseen interaction was worked for a three-dimensional lattice but it failed in two important respects: it overestimated the friction factor for long wavelength modes and did not predict a previously observed propagating transverse mode. Both of these failures were corrected by a hydrodynamic model based on periodic solutions to the Stokes equation. In addition, the effects of fluid inertia and constraining walls were considered. Intensity autocorrelation spectroscopy was used to probe the lattice dynamics by measuring the phonon dispersion curves. A thin-film cell was used to reduce multiple scattering to acceptable levels. An experiment to measure wall effects on Brownian motion was necessary to determine the decrease in diffusion rate inherent in the thin-film geometry. The wall effects were found to agree with macroscopic hydrodynamics. An additional experiment measured the elastic anisotropy of the crystal lattice from the thermal diffuse scattering. The theoretical dispersion curves were found to agree well with the measured curves.

Robust Models for Optic Flow Coding in Natural Scenes Inspired by Insect Biology

PubMed Central

Brinkworth, Russell S. A.; O'Carroll, David C.

2009-01-01

The extraction of accurate self-motion information from the visual world is a difficult problem that has been solved very efficiently by biological organisms utilizing non-linear processing. Previous bio-inspired models for motion detection based on a correlation mechanism have been dogged by issues that arise from their sensitivity to undesired properties of the image, such as contrast, which vary widely between images. Here we present a model with multiple levels of non-linear dynamic adaptive components based directly on the known or suspected responses of neurons within the visual motion pathway of the fly brain. By testing the model under realistic high-dynamic range conditions we show that the addition of these elements makes the motion detection model robust across a large variety of images, velocities and accelerations. Furthermore the performance of the entire system is more than the incremental improvements offered by the individual components, indicating beneficial non-linear interactions between processing stages. The algorithms underlying the model can be implemented in either digital or analog hardware, including neuromorphic analog VLSI, but defy an analytical solution due to their dynamic non-linear operation. The successful application of this algorithm has applications in the development of miniature autonomous systems in defense and civilian roles, including robotics, miniature unmanned aerial vehicles and collision avoidance sensors. PMID:19893631

Motion and properties of nuclear radio components in Seyfert galaxies seen with VLBI

NASA Astrophysics Data System (ADS)

Middelberg, E.; Roy, A. L.; Nagar, N. M.; Krichbaum, T. P.; Norris, R. P.; Wilson, A. S.; Falcke, H.; Colbert, E. J. M.; Witzel, A.; Fricke, K. J.

2004-04-01

We report EVN, MERLIN and VLBA observations at 18 cm, 6 cm and 3.6 cm of the Seyfert galaxies NGC 7674, NGC 5506, NGC 2110 and Mrk 1210 to study their structure and proper motions on pc scales and to add some constraints on the many possible causes of the radio-quietness of Seyferts. The component configurations in NGC 7674 and NGC 2110 are simple, linear structures, whereas the configurations in NGC 5506 and Mrk 1210 have multiple components with no clear axis of symmetry. We suggest that NGC 7674 is a low-luminosity compact symmetric object. Comparing the images at different epochs, we find a proper motion in NGC 7674 of (0.92±0.07) c between the two central components separated by 282 pc and, in NGC 5506, we find a 3 σ upper limit of 0.50 c for the components separated by 3.8 pc. Our results confirm and extend earlier work showing that the outward motion of radio components in Seyfert galaxies is non-relativistic on pc scales. We briefly discuss whether this non-relativistic motion is intrinsic to the jet-formation process or results from deceleration of an initially relativistic jet by interaction with the pc or sub-pc scale interstellar medium. We combined our sample with a list compiled from the literature of VLBI observations made of Seyfert galaxies, and found that most Seyfert nuclei have at least one flat-spectrum component on the VLBI scale, which was not seen in the spectral indices measured at arcsec resolution. We found also that the bimodal alignment of pc and kpc radio structures displayed by radio galaxies and quasars is not displayed by this sample of Seyferts, which shows a uniform distribution of misalignment between 0° and 90°. The frequent misalignment could result from jet precession or from deflection of the jet by interaction with gas in the interstellar medium.

Analysis in Motion Initiative – Summarization Capability

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

Arendt, Dustin; Pirrung, Meg; Jasper, Rob

2017-06-22

Analysts are tasked with integrating information from multiple data sources for important and timely decision making. What if sense making and overall situation awareness could be improved through visualization techniques? The Analysis in Motion initiative is advancing the ability to summarize and abstract multiple streams and static data sources over time.

Self-Motion Impairs Multiple-Object Tracking

ERIC Educational Resources Information Center

Thomas, Laura E.; Seiffert, Adriane E.

2010-01-01

Investigations of multiple-object tracking aim to further our understanding of how people perform common activities such as driving in traffic. However, tracking tasks in the laboratory have overlooked a crucial component of much real-world object tracking: self-motion. We investigated the hypothesis that keeping track of one's own movement…

Method to Reduce Target Motion Through Needle-Tissue Interactions.

PubMed

Oldfield, Matthew J; Leibinger, Alexander; Seah, Tian En Timothy; Rodriguez Y Baena, Ferdinando

2015-11-01

During minimally invasive surgical procedures, it is often important to deliver needles to particular tissue volumes. Needles, when interacting with a substrate, cause deformation and target motion. To reduce reliance on compensatory intra-operative imaging, a needle design and novel delivery mechanism is proposed. Three-dimensional finite element simulations of a multi-segment needle inserted into a pre-existing crack are presented. The motion profiles of the needle segments are varied to identify methods that reduce target motion. Experiments are then performed by inserting a needle into a gelatine tissue phantom and measuring the internal target motion using digital image correlation. Simulations indicate that target motion is reduced when needle segments are stroked cyclically and utilise a small amount of retraction instead of being held stationary. Results are confirmed experimentally by statistically significant target motion reductions of more than 8% during cyclic strokes and 29% when also incorporating retraction, with the same net insertion speed. By using a multi-segment needle and taking advantage of frictional interactions on the needle surface, it is demonstrated that target motion ahead of an advancing needle can be substantially reduced.

Three scales of motions associated with tornadoes. [Cyclones, tornadoes, and suction vortexs

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

Forbes, G.S.

1978-03-01

This dissertation explores three scales of motion commonly associated with tornadoes, and the interaction of these scales: the tornado cyclone, the tornado, and the suction vortex. The goal of the research is to specify in detail the character and interaction of these scales of motion to explain tornadic phenomena.

Active Joint Mechanism Driven by Multiple Actuators Made of Flexible Bags: A Proposal of Dual Structural Actuator

PubMed Central

Inou, Norio

2013-01-01

An actuator is required to change its speed and force depending on the situation. Using multiple actuators for one driving axis is one of the possible solutions; however, there is an associated problem of output power matching. This study proposes a new active joint mechanism using multiple actuators. Because the actuator is made of a flexible bag, it does not interfere with other actuators when it is depressurized. The proposed joint achieved coordinated motion of multiple actuators. This report also discusses a new actuator which has dual cylindrical structure. The cylinders are composed of flexible bags with different diameters. The joint torque is estimated based on the following factors: empirical formula for the flexible actuator torque, geometric relationship between the joint and the actuator, and the principle of virtual work. The prototype joint mechanism achieves coordinated motion of multiple actuators for one axis. With this motion, small inner actuator contributes high speed motion, whereas large outer actuator generates high torque. The performance of the prototype joint is examined by speed and torque measurements. The joint showed about 30% efficiency at 2.0 Nm load torque under 0.15 MPa air input. PMID:24385868

Active joint mechanism driven by multiple actuators made of flexible bags: a proposal of dual structural actuator.

PubMed

Kimura, Hitoshi; Matsuzaki, Takuya; Kataoka, Mokutaro; Inou, Norio

2013-01-01

An actuator is required to change its speed and force depending on the situation. Using multiple actuators for one driving axis is one of the possible solutions; however, there is an associated problem of output power matching. This study proposes a new active joint mechanism using multiple actuators. Because the actuator is made of a flexible bag, it does not interfere with other actuators when it is depressurized. The proposed joint achieved coordinated motion of multiple actuators. This report also discusses a new actuator which has dual cylindrical structure. The cylinders are composed of flexible bags with different diameters. The joint torque is estimated based on the following factors: empirical formula for the flexible actuator torque, geometric relationship between the joint and the actuator, and the principle of virtual work. The prototype joint mechanism achieves coordinated motion of multiple actuators for one axis. With this motion, small inner actuator contributes high speed motion, whereas large outer actuator generates high torque. The performance of the prototype joint is examined by speed and torque measurements. The joint showed about 30% efficiency at 2.0 Nm load torque under 0.15 MPa air input.

Response analysis of a nuclear containment structure with nonlinear soil-structure interaction under bi-directional ground motion

NASA Astrophysics Data System (ADS)

Kumar, Santosh; Raychowdhury, Prishati; Gundlapalli, Prabhakar

2015-06-01

Design of critical facilities such as nuclear power plant requires an accurate and precise evaluation of seismic demands, as any failure of these facilities poses immense threat to the community. Design complexity of these structures reinforces the necessity of a robust 3D modeling and analysis of the structure and the soil-foundation interface. Moreover, it is important to consider the multiple components of ground motion during time history analysis for a realistic simulation. Present study is focused on investigating the seismic response of a nuclear containment structure considering nonlinear Winkler-based approach to model the soil-foundation interface using a distributed array of inelastic springs, dashpots and gap elements. It is observed from this study that the natural period of the structure increases about 10 %, whereas the force demands decreases up to 24 % by considering the soil-structure interaction. Further, it is observed that foundation deformations, such as rotation and sliding are affected by the embedment ratio, indicating an increase of up to 56 % in these responses for a reduction of embedment from 0.5 to 0.05× the width of the footing.

Spinal circuits can accommodate interaction torques during multijoint limb movements.

PubMed

Buhrmann, Thomas; Di Paolo, Ezequiel A

2014-01-01

The dynamic interaction of limb segments during movements that involve multiple joints creates torques in one joint due to motion about another. Evidence shows that such interaction torques are taken into account during the planning or control of movement in humans. Two alternative hypotheses could explain the compensation of these dynamic torques. One involves the use of internal models to centrally compute predicted interaction torques and their explicit compensation through anticipatory adjustment of descending motor commands. The alternative, based on the equilibrium-point hypothesis, claims that descending signals can be simple and related to the desired movement kinematics only, while spinal feedback mechanisms are responsible for the appropriate creation and coordination of dynamic muscle forces. Partial supporting evidence exists in each case. However, until now no model has explicitly shown, in the case of the second hypothesis, whether peripheral feedback is really sufficient on its own for coordinating the motion of several joints while at the same time accommodating intersegmental interaction torques. Here we propose a minimal computational model to examine this question. Using a biomechanics simulation of a two-joint arm controlled by spinal neural circuitry, we show for the first time that it is indeed possible for the neuromusculoskeletal system to transform simple descending control signals into muscle activation patterns that accommodate interaction forces depending on their direction and magnitude. This is achieved without the aid of any central predictive signal. Even though the model makes various simplifications and abstractions compared to the complexities involved in the control of human arm movements, the finding lends plausibility to the hypothesis that some multijoint movements can in principle be controlled even in the absence of internal models of intersegmental dynamics or learned compensatory motor signals.

Hydrodynamic interaction of two deformable drops in confined shear flow.

PubMed

Chen, Yongping; Wang, Chengyao

2014-09-01

We investigate hydrodynamic interaction between two neutrally buoyant circular drops in a confined shear flow based on a computational fluid dynamics simulation using the volume-of-fluid method. The rheological behaviors of interactive drops and the flow regimes are explored with a focus on elucidation of underlying physical mechanisms. We find that two types of drop behaviors during interaction occur, including passing-over motion and reversing motion, which are governed by the competition between the drag of passing flow and the entrainment of reversing flow in matrix fluid. With the increasing confinement, the drop behavior transits from the passing-over motion to reversing motion, because the entrainment of the reversing-flow matrix fluid turns to play the dominant role. The drag of the ambient passing flow is increased by enlarging the initial lateral separation due to the departure of the drop from the reversing flow in matrix fluid, resulting in the emergence of passing-over motion. In particular, a corresponding phase diagram is plotted to quantitatively illustrate the dependence of drop morphologies during interaction on confinement and initial lateral separation.

Exploring the bases for a mixed reality stroke rehabilitation system, Part II: design of interactive feedback for upper limb rehabilitation.

PubMed

Lehrer, Nicole; Chen, Yinpeng; Duff, Margaret; L Wolf, Steven; Rikakis, Thanassis

2011-09-08

Few existing interactive rehabilitation systems can effectively communicate multiple aspects of movement performance simultaneously, in a manner that appropriately adapts across various training scenarios. In order to address the need for such systems within stroke rehabilitation training, a unified approach for designing interactive systems for upper limb rehabilitation of stroke survivors has been developed and applied for the implementation of an Adaptive Mixed Reality Rehabilitation (AMRR) System. The AMRR system provides computational evaluation and multimedia feedback for the upper limb rehabilitation of stroke survivors. A participant's movements are tracked by motion capture technology and evaluated by computational means. The resulting data are used to generate interactive media-based feedback that communicates to the participant detailed, intuitive evaluations of his performance. This article describes how the AMRR system's interactive feedback is designed to address specific movement challenges faced by stroke survivors. Multimedia examples are provided to illustrate each feedback component. Supportive data are provided for three participants of varying impairment levels to demonstrate the system's ability to train both targeted and integrated aspects of movement. The AMRR system supports training of multiple movement aspects together or in isolation, within adaptable sequences, through cohesive feedback that is based on formalized compositional design principles. From preliminary analysis of the data, we infer that the system's ability to train multiple foci together or in isolation in adaptable sequences, utilizing appropriately designed feedback, can lead to functional improvement. The evaluation and feedback frameworks established within the AMRR system will be applied to the development of a novel home-based system to provide an engaging yet low-cost extension of training for longer periods of time.

Exploring the bases for a mixed reality stroke rehabilitation system, Part II: Design of Interactive Feedback for upper limb rehabilitation

PubMed Central

2011-01-01

Background Few existing interactive rehabilitation systems can effectively communicate multiple aspects of movement performance simultaneously, in a manner that appropriately adapts across various training scenarios. In order to address the need for such systems within stroke rehabilitation training, a unified approach for designing interactive systems for upper limb rehabilitation of stroke survivors has been developed and applied for the implementation of an Adaptive Mixed Reality Rehabilitation (AMRR) System. Results The AMRR system provides computational evaluation and multimedia feedback for the upper limb rehabilitation of stroke survivors. A participant's movements are tracked by motion capture technology and evaluated by computational means. The resulting data are used to generate interactive media-based feedback that communicates to the participant detailed, intuitive evaluations of his performance. This article describes how the AMRR system's interactive feedback is designed to address specific movement challenges faced by stroke survivors. Multimedia examples are provided to illustrate each feedback component. Supportive data are provided for three participants of varying impairment levels to demonstrate the system's ability to train both targeted and integrated aspects of movement. Conclusions The AMRR system supports training of multiple movement aspects together or in isolation, within adaptable sequences, through cohesive feedback that is based on formalized compositional design principles. From preliminary analysis of the data, we infer that the system's ability to train multiple foci together or in isolation in adaptable sequences, utilizing appropriately designed feedback, can lead to functional improvement. The evaluation and feedback frameworks established within the AMRR system will be applied to the development of a novel home-based system to provide an engaging yet low-cost extension of training for longer periods of time. PMID:21899779

Long-latency reflexes of elbow and shoulder muscles suggest reciprocal excitation of flexors, reciprocal excitation of extensors, and reciprocal inhibition between flexors and extensors

PubMed Central

Meriggi, Jenna; Parikh, Nidhi; Saad, Kenneth

2016-01-01

Postural corrections of the upper limb are required in tasks ranging from handling an umbrella in the changing wind to securing a wriggling baby. One complication in this process is the mechanical interaction between the different segments of the arm where torque applied at one joint induces motion at multiple joints. Previous studies have shown the long-latency reflexes of shoulder muscles (50–100 ms after a limb perturbation) account for these mechanical interactions by integrating information about motion of both the shoulder and elbow. It is less clear whether long-latency reflexes of elbow muscles exhibit a similar capability and what is the relation between the responses of shoulder and elbow muscles. The present study utilized joint-based loads tailored to the subjects' arm dynamics to induce well-controlled displacements of their shoulder and elbow. Our results demonstrate that the long-latency reflexes of shoulder and elbow muscles integrate motion from both joints: the shoulder and elbow flexors respond to extension at both joints, whereas the shoulder and elbow extensors respond to flexion at both joints. This general pattern accounts for the inherent flexion-extension coupling of the two joints arising from the arm's intersegmental dynamics and is consistent with spindle-based reciprocal excitation of shoulder and elbow flexors, reciprocal excitation of shoulder and elbow extensors, and across-joint inhibition between the flexors and extensors. PMID:26864766

Collective motion of groups of self-propelled particles following interacting leaders

NASA Astrophysics Data System (ADS)

Ferdinandy, B.; Ozogány, K.; Vicsek, T.

2017-08-01

In order to keep their cohesiveness during locomotion gregarious animals must make collective decisions. Many species boast complex societies with multiple levels of communities. A common case is when two dominant levels exist, one corresponding to leaders and the other consisting of followers. In this paper we study the collective motion of such two-level assemblies of self-propelled particles. We present a model adapted from one originally proposed to describe the movement of cells resulting in a smoothly varying coherent motion. We shall use the terminology corresponding to large groups of some mammals where leaders and followers form a group called a harem. We study the emergence (self-organization) of sub-groups within a herd during locomotion by computer simulations. The resulting processes are compared with our prior observations of a Przewalski horse herd (Hortobágy, Hungary) which we use as results from a published case study. We find that the model reproduces key features of a herd composed of harems moving on open ground, including fights for followers between leaders and bachelor groups (group of leaders without followers). One of our findings, however, does not agree with the observations. While in our model the emerging group size distribution is normal, the group size distribution of the observed herd based on historical data have been found to follow lognormal distribution. We argue that this indicates that the formation (and the size) of the harems must involve a more complex social topology than simple spatial-distance based interactions.

A slowly moving foreground can capture an observer's self-motion--a report of a new motion illusion: inverted vection.

PubMed

Nakamura, S; Shimojo, S

2000-01-01

We investigated interactions between foreground and background stimuli during visually induced perception of self-motion (vection) by using a stimulus composed of orthogonally moving random-dot patterns. The results indicated that, when the foreground moves with a slower speed, a self-motion sensation with a component in the same direction as the foreground is induced. We named this novel component of self-motion perception 'inverted vection'. The robustness of inverted vection was confirmed using various measures of self-motion sensation and under different stimulus conditions. The mechanism underlying inverted vection is discussed with regard to potentially relevant factors, such as relative motion between the foreground and background, and the interaction between the mis-registration of eye-movement information and self-motion perception.

Multidimensional joint coupling: a case study visualisation approach to movement coordination and variability.

PubMed

Irwin, Gareth; Kerwin, David G; Williams, Genevieve; Van Emmerik, Richard E A; Newell, Karl M; Hamill, Joseph

2018-06-18

A case study visualisation approach to examining the coordination and variability of multiple interacting segments is presented using a whole-body gymnastic skill as the task example. One elite male gymnast performed 10 trials of 10 longswings whilst three-dimensional locations of joint centres were tracked using a motion analysis system. Segment angles were used to define coupling between the arms and trunk, trunk and thighs and thighs and shanks. Rectified continuous relative phase profiles for each interacting couple for 80 longswings were produced. Graphical representations of coordination couplings are presented that include the traditional single coupling, followed by the relational dynamics of two couplings and finally three couplings simultaneously plotted. This method highlights the power of visualisation of movement dynamics and identifies properties of the global interacting segmental couplings that a more formal analysis may not reveal. Visualisation precedes and informs the appropriate qualitative and quantitative analysis of the dynamics.

The effect of side motion in the dynamics of interacting molecular motors

NASA Astrophysics Data System (ADS)

Midha, Tripti; Gupta, Arvind Kumar; Kolomeisky, Anatoly B.

2017-07-01

To mimic the collective motion of interacting molecular motors, we propose and discuss an open two-lane symmetrically coupled interactive TASEP model that incorporates interaction in the thermodynamically consistent fashion. We study the effect of both repulsive and attractive interaction on the system’s dynamical properties using various cluster mean field analysis and extensive Monte Carlo simulations. The interactions bring correlations into the system, which were found to be reduced due to the side motion of particles. We produce the steady-state phase diagrams for symmetrically split interaction strength. The behavior of the maximal particle current with respect to the interaction energy E is analyzed for different coupling rates and interaction splittings. The results suggest that for strong coupling and large splittings, the maximal flow of the motors occurs at a weak attractive interaction strength which matches with the known experimental results on kinesin motor protein.

A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation

NASA Astrophysics Data System (ADS)

Shen, Qi; Trabia, Sarah; Stalbaum, Tyler; Palmre, Viljar; Kim, Kwang; Oh, Il-Kwon

2016-04-01

Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors’ knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability.

A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation

PubMed Central

Shen, Qi; Trabia, Sarah; Stalbaum, Tyler; Palmre, Viljar; Kim, Kwang; Oh, Il-Kwon

2016-01-01

Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors’ knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability. PMID:27080134

A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation.

PubMed

Shen, Qi; Trabia, Sarah; Stalbaum, Tyler; Palmre, Viljar; Kim, Kwang; Oh, Il-Kwon

2016-04-15

Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors' knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability.

KOLAM: a cross-platform architecture for scalable visualization and tracking in wide-area imagery

NASA Astrophysics Data System (ADS)

Fraser, Joshua; Haridas, Anoop; Seetharaman, Guna; Rao, Raghuveer M.; Palaniappan, Kannappan

2013-05-01

KOLAM is an open, cross-platform, interoperable, scalable and extensible framework supporting a novel multi- scale spatiotemporal dual-cache data structure for big data visualization and visual analytics. This paper focuses on the use of KOLAM for target tracking in high-resolution, high throughput wide format video also known as wide-area motion imagery (WAMI). It was originally developed for the interactive visualization of extremely large geospatial imagery of high spatial and spectral resolution. KOLAM is platform, operating system and (graphics) hardware independent, and supports embedded datasets scalable from hundreds of gigabytes to feasibly petabytes in size on clusters, workstations, desktops and mobile computers. In addition to rapid roam, zoom and hyper- jump spatial operations, a large number of simultaneously viewable embedded pyramid layers (also referred to as multiscale or sparse imagery), interactive colormap and histogram enhancement, spherical projection and terrain maps are supported. The KOLAM software architecture was extended to support airborne wide-area motion imagery by organizing spatiotemporal tiles in very large format video frames using a temporal cache of tiled pyramid cached data structures. The current version supports WAMI animation, fast intelligent inspection, trajectory visualization and target tracking (digital tagging); the latter by interfacing with external automatic tracking software. One of the critical needs for working with WAMI is a supervised tracking and visualization tool that allows analysts to digitally tag multiple targets, quickly review and correct tracking results and apply geospatial visual analytic tools on the generated trajectories. One-click manual tracking combined with multiple automated tracking algorithms are available to assist the analyst and increase human effectiveness.

Statistical prediction of space motion sickness

NASA Technical Reports Server (NTRS)

Reschke, Millard F.

1990-01-01

Studies designed to empirically examine the etiology of motion sickness to develop a foundation for enhancing its prediction are discussed. Topics addressed include early attempts to predict space motion sickness, multiple test data base that uses provocative and vestibular function tests, and data base subjects; reliability of provocative tests of motion sickness susceptibility; prediction of space motion sickness using linear discriminate analysis; and prediction of space motion sickness susceptibility using the logistic model.

Commercial Motion Sensor Based Low-Cost and Convenient Interactive Treadmill.

PubMed

Kim, Jonghyun; Gravunder, Andrew; Park, Hyung-Soon

2015-09-17

Interactive treadmills were developed to improve the simulation of overground walking when compared to conventional treadmills. However, currently available interactive treadmills are expensive and inconvenient, which limits their use. We propose a low-cost and convenient version of the interactive treadmill that does not require expensive equipment and a complicated setup. As a substitute for high-cost sensors, such as motion capture systems, a low-cost motion sensor was used to recognize the subject's intention for speed changing. Moreover, the sensor enables the subject to make a convenient and safe stop using gesture recognition. For further cost reduction, the novel interactive treadmill was based on an inexpensive treadmill platform and a novel high-level speed control scheme was applied to maximize performance for simulating overground walking. Pilot tests with ten healthy subjects were conducted and results demonstrated that the proposed treadmill achieves similar performance to a typical, costly, interactive treadmill that contains a motion capture system and an instrumented treadmill, while providing a convenient and safe method for stopping.

Motion compensation via redundant-wavelet multihypothesis.

PubMed

Fowler, James E; Cui, Suxia; Wang, Yonghui

2006-10-01

Multihypothesis motion compensation has been widely used in video coding with previous attention focused on techniques employing predictions that are diverse spatially or temporally. In this paper, the multihypothesis concept is extended into the transform domain by using a redundant wavelet transform to produce multiple predictions that are diverse in transform phase. The corresponding multiple-phase inverse transform implicitly combines the phase-diverse predictions into a single spatial-domain prediction for motion compensation. The performance advantage of this redundant-wavelet-multihypothesis approach is investigated analytically, invoking the fact that the multiple-phase inverse involves a projection that significantly reduces the power of a dense-motion residual modeled as additive noise. The analysis shows that redundant-wavelet multihypothesis is capable of up to a 7-dB reduction in prediction-residual variance over an equivalent single-phase, single-hypothesis approach. Experimental results substantiate the performance advantage for a block-based implementation.

Controlling the motion of multiple objects on a Chladni plate

NASA Astrophysics Data System (ADS)

Zhou, Quan; Sariola, Veikko; Latifi, Kourosh; Liimatainen, Ville

2016-09-01

The origin of the idea of moving objects by acoustic vibration can be traced back to 1787, when Ernst Chladni reported the first detailed studies on the aggregation of sand onto nodal lines of a vibrating plate. Since then and to this date, the prevailing view has been that the particle motion out of nodal lines is random, implying uncontrollability. But how random really is the out-of-nodal-lines motion on a Chladni plate? Here we show that the motion is sufficiently regular to be statistically modelled, predicted and controlled. By playing carefully selected musical notes, we can control the position of multiple objects simultaneously and independently using a single acoustic actuator. Our method allows independent trajectory following, pattern transformation and sorting of multiple miniature objects in a wide range of materials, including electronic components, water droplets loaded on solid carriers, plant seeds, candy balls and metal parts.

Motion Field Estimation for a Dynamic Scene Using a 3D LiDAR

PubMed Central

Li, Qingquan; Zhang, Liang; Mao, Qingzhou; Zou, Qin; Zhang, Pin; Feng, Shaojun; Ochieng, Washington

2014-01-01

This paper proposes a novel motion field estimation method based on a 3D light detection and ranging (LiDAR) sensor for motion sensing for intelligent driverless vehicles and active collision avoidance systems. Unlike multiple target tracking methods, which estimate the motion state of detected targets, such as cars and pedestrians, motion field estimation regards the whole scene as a motion field in which each little element has its own motion state. Compared to multiple target tracking, segmentation errors and data association errors have much less significance in motion field estimation, making it more accurate and robust. This paper presents an intact 3D LiDAR-based motion field estimation method, including pre-processing, a theoretical framework for the motion field estimation problem and practical solutions. The 3D LiDAR measurements are first projected to small-scale polar grids, and then, after data association and Kalman filtering, the motion state of every moving grid is estimated. To reduce computing time, a fast data association algorithm is proposed. Furthermore, considering the spatial correlation of motion among neighboring grids, a novel spatial-smoothing algorithm is also presented to optimize the motion field. The experimental results using several data sets captured in different cities indicate that the proposed motion field estimation is able to run in real-time and performs robustly and effectively. PMID:25207868

Motion field estimation for a dynamic scene using a 3D LiDAR.

PubMed

Li, Qingquan; Zhang, Liang; Mao, Qingzhou; Zou, Qin; Zhang, Pin; Feng, Shaojun; Ochieng, Washington

2014-09-09

This paper proposes a novel motion field estimation method based on a 3D light detection and ranging (LiDAR) sensor for motion sensing for intelligent driverless vehicles and active collision avoidance systems. Unlike multiple target tracking methods, which estimate the motion state of detected targets, such as cars and pedestrians, motion field estimation regards the whole scene as a motion field in which each little element has its own motion state. Compared to multiple target tracking, segmentation errors and data association errors have much less significance in motion field estimation, making it more accurate and robust. This paper presents an intact 3D LiDAR-based motion field estimation method, including pre-processing, a theoretical framework for the motion field estimation problem and practical solutions. The 3D LiDAR measurements are first projected to small-scale polar grids, and then, after data association and Kalman filtering, the motion state of every moving grid is estimated. To reduce computing time, a fast data association algorithm is proposed. Furthermore, considering the spatial correlation of motion among neighboring grids, a novel spatial-smoothing algorithm is also presented to optimize the motion field. The experimental results using several data sets captured in different cities indicate that the proposed motion field estimation is able to run in real-time and performs robustly and effectively.

Main Cause of the Poloidal Plasma Motion Inside a Magnetic Cloud Inferred from Multiple-Spacecraft Observations

NASA Astrophysics Data System (ADS)

Zhao, Ake; Wang, Yuming; Chi, Yutian; Liu, Jiajia; Shen, Chenglong; Liu, Rui

2017-04-01

Although the dynamical evolution of magnetic clouds (MCs) has been one of the foci of interplanetary physics for decades, only few studies focus on the internal properties of large-scale MCs. Recent work by Wang et al. ( J. Geophys. Res. 120, 1543, 2015) suggested the existence of the poloidal plasma motion in MCs. However, the main cause of this motion is not clear. In order to find it, we identify and reconstruct the MC observed by the Solar Terrestrial Relations Observatory (STEREO)-A, Wind, and STEREO-B spacecraft during 19 - 20 November 2007 with the aid of the velocity-modified cylindrical force-free flux-rope model. We analyze the plasma velocity in the plane perpendicular to the MC axis. It is found that there was evident poloidal motion at Wind and STEREO-B, but this was not clear at STEREO-A, which suggests a local cause rather than a global cause for the poloidal plasma motion inside the MC. The rotational directions of the solar wind and MC plasma at the two sides of the MC boundary are found to be consistent, and the values of the rotational speeds of the solar wind and MC plasma at the three spacecraft show a rough correlation. All of these results illustrate that the interaction with ambient solar wind through viscosity might be one of the local causes of the poloidal motion. Additionally, we propose another possible local cause: the existence of a pressure gradient in the MC. The significant difference in the total pressure at the three spacecraft suggests that this speculation is perhaps correct.

Probing Motion of Fast Radio Burst Sources by Timing Strongly Lensed Repeaters

NASA Astrophysics Data System (ADS)

Dai, Liang; Lu, Wenbin

2017-09-01

Given the possible repetitive nature of fast radio bursts (FRBs), their cosmological origin, and their high occurrence, detection of strongly lensed sources due to intervening galaxy lenses is possible with forthcoming radio surveys. We show that if multiple images of a repeating source are resolved with VLBI, using a method independent of lens modeling, accurate timing could reveal non-uniform motion, either physical or apparent, of the emission spot. This can probe the physical nature of FRBs and their surrounding environments, constraining scenarios including orbital motion around a stellar companion if FRBs require a compact star in a special system, and jet-medium interactions for which the location of the emission spot may randomly vary. The high timing precision possible for FRBs (˜ms) compared with the typical time delays between images in galaxy lensing (≳10 days) enables the measurement of tiny fractional changes in the delays (˜ {10}-9) and hence the detection of time-delay variations induced by relative motions between the source, the lens, and the Earth. We show that uniform cosmic peculiar velocities only cause the delay time to drift linearly, and that the effect from the Earth’s orbital motion can be accurately subtracted, thus enabling a search for non-trivial source motion. For a timing accuracy of ˜1 ms and a repetition rate (of detected bursts) of ˜0.05 per day of a single FRB source, non-uniform displacement ≳0.1-1 au of the emission spot perpendicular to the line of sight is detectable if repetitions are seen over a period of hundreds of days.

Multi-modal gesture recognition using integrated model of motion, audio and video

NASA Astrophysics Data System (ADS)

Goutsu, Yusuke; Kobayashi, Takaki; Obara, Junya; Kusajima, Ikuo; Takeichi, Kazunari; Takano, Wataru; Nakamura, Yoshihiko

2015-07-01

Gesture recognition is used in many practical applications such as human-robot interaction, medical rehabilitation and sign language. With increasing motion sensor development, multiple data sources have become available, which leads to the rise of multi-modal gesture recognition. Since our previous approach to gesture recognition depends on a unimodal system, it is difficult to classify similar motion patterns. In order to solve this problem, a novel approach which integrates motion, audio and video models is proposed by using dataset captured by Kinect. The proposed system can recognize observed gestures by using three models. Recognition results of three models are integrated by using the proposed framework and the output becomes the final result. The motion and audio models are learned by using Hidden Markov Model. Random Forest which is the video classifier is used to learn the video model. In the experiments to test the performances of the proposed system, the motion and audio models most suitable for gesture recognition are chosen by varying feature vectors and learning methods. Additionally, the unimodal and multi-modal models are compared with respect to recognition accuracy. All the experiments are conducted on dataset provided by the competition organizer of MMGRC, which is a workshop for Multi-Modal Gesture Recognition Challenge. The comparison results show that the multi-modal model composed of three models scores the highest recognition rate. This improvement of recognition accuracy means that the complementary relationship among three models improves the accuracy of gesture recognition. The proposed system provides the application technology to understand human actions of daily life more precisely.

Interaction of non-radially symmetric camphor particles

NASA Astrophysics Data System (ADS)

Ei, Shin-Ichiro; Kitahata, Hiroyuki; Koyano, Yuki; Nagayama, Masaharu

2018-03-01

In this study, the interaction between two non-radially symmetric camphor particles is theoretically investigated and the equation describing the motion is derived as an ordinary differential system for the locations and the rotations. In particular, slightly modified non-radially symmetric cases from radial symmetry are extensively investigated and explicit motions are obtained. For example, it is theoretically shown that elliptically deformed camphor particles interact so as to be parallel with major axes. Such predicted motions are also checked by real experiments and numerical simulations.

Modeling microcapsules that communicate through nanoparticles to undergo self-propelled motion.

PubMed

Usta, O Berk; Alexeev, Alexander; Zhu, Guangdong; Balazs, Anna C

2008-03-01

Using simulation and theory, we demonstrate how nanoparticles can be harnessed to regulate the interaction between two initially stationary microcapsules on a surface and promote the self-propelled motion of these capsules along the substrate. The first microcapsule, the "signaling" capsule, encases nanoparticles, which diffuse from the interior of this carrier and into the surrounding solution; the second capsule is the "target" capsule, which is initially devoid of particles. Nanoparticles released from the signaling capsule modify the underlying substrate and thereby initiate the motion of the target capsule. The latter motion activates hydrodynamic interactions, which trigger the signaling capsule to follow the target. The continued release of the nanoparticles sustains the motion of both capsules. In effect, the system constitutes a synthetic analogue of biological cell signaling and our findings can shed light on fundamental physical forces that control interactions between cells. Our findings can also yield guidelines for manipulating the interactions of synthetic microcapsules in microfluidic devices.

A Regulatory Switch Alters Chromosome Motions at the Metaphase to Anaphase Transition

PubMed Central

Su, Kuan-Chung; Barry, Zachary; Schweizer, Nina; Maiato, Helder; Bathe, Mark; Cheeseman, Iain McPherson

2016-01-01

Summary To achieve chromosome segregation during mitosis, sister chromatids must undergo a dramatic change in their behavior to switch from balanced oscillations at the metaphase plate to directed poleward motion during anaphase. However, the factors that alter chromosome behavior at the metaphase-to-anaphase transition remain incompletely understood. Here, we perform time-lapse imaging to analyze anaphase chromosome dynamics in human cells. Using multiple directed biochemical, genetic, and physical perturbations, our results demonstrate that differences in the global phosphorylation states between metaphase and anaphase are the major determinant of chromosome motion dynamics. Indeed, causing a mitotic phosphorylation state to persist into anaphase produces dramatic metaphase-like oscillations. These induced oscillations depend on both kinetochore-derived and polar ejection forces that oppose poleward motion. Thus, our analysis of anaphase chromosome motion reveals that dephosphorylation of multiple mitotic substrates is required to suppress metaphase chromosome oscillatory motions and achieve directed poleward motion for successful chromosome segregation. PMID:27829144

Towards Gesture-Based Multi-User Interactions in Collaborative Virtual Environments

NASA Astrophysics Data System (ADS)

Pretto, N.; Poiesi, F.

2017-11-01

We present a virtual reality (VR) setup that enables multiple users to participate in collaborative virtual environments and interact via gestures. A collaborative VR session is established through a network of users that is composed of a server and a set of clients. The server manages the communication amongst clients and is created by one of the users. Each user's VR setup consists of a Head Mounted Display (HMD) for immersive visualisation, a hand tracking system to interact with virtual objects and a single-hand joypad to move in the virtual environment. We use Google Cardboard as a HMD for the VR experience and a Leap Motion for hand tracking, thus making our solution low cost. We evaluate our VR setup though a forensics use case, where real-world objects pertaining to a simulated crime scene are included in a VR environment, acquired using a smartphone-based 3D reconstruction pipeline. Users can interact using virtual gesture-based tools such as pointers and rulers.

The molecular mechanism of nuclear transport revealed by atomic-scale measurements

PubMed Central

Hough, Loren E; Dutta, Kaushik; Sparks, Samuel; Temel, Deniz B; Kamal, Alia; Tetenbaum-Novatt, Jaclyn; Rout, Michael P; Cowburn, David

2015-01-01

Nuclear pore complexes (NPCs) form a selective filter that allows the rapid passage of transport factors (TFs) and their cargoes across the nuclear envelope, while blocking the passage of other macromolecules. Intrinsically disordered proteins (IDPs) containing phenylalanyl-glycyl (FG)-rich repeats line the pore and interact with TFs. However, the reason that transport can be both fast and specific remains undetermined, through lack of atomic-scale information on the behavior of FGs and their interaction with TFs. We used nuclear magnetic resonance spectroscopy to address these issues. We show that FG repeats are highly dynamic IDPs, stabilized by the cellular environment. Fast transport of TFs is supported because the rapid motion of FG motifs allows them to exchange on and off TFs extremely quickly through transient interactions. Because TFs uniquely carry multiple pockets for FG repeats, only they can form the many frequent interactions needed for specific passage between FG repeats to cross the NPC. DOI: http://dx.doi.org/10.7554/eLife.10027.001 PMID:26371551

Optical Trapping of Ion Coulomb Crystals

NASA Astrophysics Data System (ADS)

Schmidt, Julian; Lambrecht, Alexander; Weckesser, Pascal; Debatin, Markus; Karpa, Leon; Schaetz, Tobias

2018-04-01

The electronic and motional degrees of freedom of trapped ions can be controlled and coherently coupled on the level of individual quanta. Assembling complex quantum systems ion by ion while keeping this unique level of control remains a challenging task. For many applications, linear chains of ions in conventional traps are ideally suited to address this problem. However, driven motion due to the magnetic or radio-frequency electric trapping fields sometimes limits the performance in one dimension and severely affects the extension to higher-dimensional systems. Here, we report on the trapping of multiple barium ions in a single-beam optical dipole trap without radio-frequency or additional magnetic fields. We study the persistence of order in ensembles of up to six ions within the optical trap, measure their temperature, and conclude that the ions form a linear chain, commonly called a one-dimensional Coulomb crystal. As a proof-of-concept demonstration, we access the collective motion and perform spectrometry of the normal modes in the optical trap. Our system provides a platform that is free of driven motion and combines advantages of optical trapping, such as state-dependent confinement and nanoscale potentials, with the desirable properties of crystals of trapped ions, such as long-range interactions featuring collective motion. Starting with small numbers of ions, it has been proposed that these properties would allow the experimental study of many-body physics and the onset of structural quantum phase transitions between one- and two-dimensional crystals.

Minimal energy configurations of gravitationally interacting rigid bodies

NASA Astrophysics Data System (ADS)

Moeckel, Richard

2017-05-01

Consider a collection of n rigid, massive bodies interacting according to their mutual gravitational attraction. A relative equilibrium motion is one where the entire configuration rotates rigidly and uniformly about a fixed axis in R^3. Such a motion is possible only for special positions and orientations of the bodies. A minimal energy motion is one which has the minimum possible energy in its fixed angular momentum level. While every minimal energy motion is a relative equilibrium motion, the main result here is that a relative equilibrium motion of n≥3 disjoint rigid bodies is never an energy minimizer. This generalizes a known result about point masses to the case of rigid bodies.

Spatiotemporal Processing in Crossmodal Interactions for Perception of the External World: A Review

PubMed Central

Hidaka, Souta; Teramoto, Wataru; Sugita, Yoichi

2015-01-01

Research regarding crossmodal interactions has garnered much interest in the last few decades. A variety of studies have demonstrated that multisensory information (vision, audition, tactile sensation, and so on) can perceptually interact with each other in the spatial and temporal domains. Findings regarding crossmodal interactions in the spatiotemporal domain (i.e., motion processing) have also been reported, with updates in the last few years. In this review, we summarize past and recent findings on spatiotemporal processing in crossmodal interactions regarding perception of the external world. A traditional view regarding crossmodal interactions holds that vision is superior to audition in spatial processing, but audition is dominant over vision in temporal processing. Similarly, vision is considered to have dominant effects over the other sensory modalities (i.e., visual capture) in spatiotemporal processing. However, recent findings demonstrate that sound could have a driving effect on visual motion perception. Moreover, studies regarding perceptual associative learning reported that, after association is established between a sound sequence without spatial information and visual motion information, the sound sequence could trigger visual motion perception. Other sensory information, such as motor action or smell, has also exhibited similar driving effects on visual motion perception. Additionally, recent brain imaging studies demonstrate that similar activation patterns could be observed in several brain areas, including the motion processing areas, between spatiotemporal information from different sensory modalities. Based on these findings, we suggest that multimodal information could mutually interact in spatiotemporal processing in the percept of the external world and that common perceptual and neural underlying mechanisms would exist for spatiotemporal processing. PMID:26733827

Loop-loop interactions govern multiple steps in indole-3-glycerol phosphate synthase catalysis

PubMed Central

Zaccardi, Margot J; O'Rourke, Kathleen F; Yezdimer, Eric M; Loggia, Laura J; Woldt, Svenja; Boehr, David D

2014-01-01

Substrate binding, product release, and likely chemical catalysis in the tryptophan biosynthetic enzyme indole-3-glycerol phosphate synthase (IGPS) are dependent on the structural dynamics of the β1α1 active-site loop. Statistical coupling analysis and molecular dynamic simulations had previously indicated that covarying residues in the β1α1 and β2α2 loops, corresponding to Arg54 and Asn90, respectively, in the Sulfolobus sulfataricus enzyme (ssIGPS), are likely important for coordinating functional motions of these loops. To test this hypothesis, we characterized site mutants at these positions for changes in catalytic function, protein stability and structural dynamics for the thermophilic ssIGPS enzyme. Although there were only modest changes in the overall steady-state kinetic parameters, solvent viscosity and solvent deuterium kinetic isotope effects indicated that these amino acid substitutions change the identity of the rate-determining step across multiple temperatures. Surprisingly, the N90A substitution had a dramatic effect on the general acid/base catalysis of the dehydration step, as indicated by the loss of the descending limb in the pH rate profile, which we had previously assigned to Lys53 on the β1α1 loop. These changes in enzyme function are accompanied with a quenching of ps-ns and µs-ms timescale motions in the β1α1 loop as measured by nuclear magnetic resonance studies. Altogether, our studies provide structural, dynamic and functional rationales for the coevolution of residues on the β1α1 and β2α2 loops, and highlight the multiple roles that the β1α1 loop plays in IGPS catalysis. Thus, substitution of covarying residues in the active-site β1α1 and β2α2 loops of indole-3-glycerol phosphate synthase results in functional, structural, and dynamic changes, highlighting the multiple roles that the β1α1 loop plays in enzyme catalysis and the importance of regulating the structural dynamics of this loop through noncovalent interactions with nearby structural elements. PMID:24403092

Unlocking higher harmonics in atomic force microscopy with gentle interactions.

PubMed

Santos, Sergio; Barcons, Victor; Font, Josep; Verdaguer, Albert

2014-01-01

In dynamic atomic force microscopy, nanoscale properties are encoded in the higher harmonics. Nevertheless, when gentle interactions and minimal invasiveness are required, these harmonics are typically undetectable. Here, we propose to externally drive an arbitrary number of exact higher harmonics above the noise level. In this way, multiple contrast channels that are sensitive to compositional variations are made accessible. Numerical integration of the equation of motion shows that the external introduction of exact harmonic frequencies does not compromise the fundamental frequency. Thermal fluctuations are also considered within the detection bandwidth of interest and discussed in terms of higher-harmonic phase contrast in the presence and absence of an external excitation of higher harmonics. Higher harmonic phase shifts further provide the means to directly decouple the true topography from that induced by compositional heterogeneity.

Unsteady Cascade Aerodynamic Response Using a Multiphysics Simulation Code

NASA Technical Reports Server (NTRS)

Lawrence, C.; Reddy, T. S. R.; Spyropoulos, E.

2000-01-01

The multiphysics code Spectrum(TM) is applied to calculate the unsteady aerodynamic pressures of oscillating cascade of airfoils representing a blade row of a turbomachinery component. Multiphysics simulation is based on a single computational framework for the modeling of multiple interacting physical phenomena, in the present case being between fluids and structures. Interaction constraints are enforced in a fully coupled manner using the augmented-Lagrangian method. The arbitrary Lagrangian-Eulerian method is utilized to account for deformable fluid domains resulting from blade motions. Unsteady pressures are calculated for a cascade designated as the tenth standard, and undergoing plunging and pitching oscillations. The predicted unsteady pressures are compared with those obtained from an unsteady Euler co-de refer-red in the literature. The Spectrum(TM) code predictions showed good correlation for the cases considered.

Harnessing wake vortices for efficient collective swimming via deep reinfrcement learning

NASA Astrophysics Data System (ADS)

Verma, Siddartha; Novati, Guido; Koumoutsakos, Petros; ChairComputing Science Team

2017-11-01

Collective motion may bestow evolutionary advantages to a number of animal species. Soaring flocks of birds, teeming swarms of insects, and swirling masses of schooling fish, all to some extent enjoy anti-predator benefits, increased foraging success, and enhanced problem-solving abilities. Coordinated activity may also provide energetic benefits, as in the case of large groups of fish where swimmers exploit unsteady flow-patterns generated in the wake. Both experimental and computational investigations of such scenarios are hampered by difficulties associated with studying multiple swimmers. Consequentially, the precise energy-saving mechanisms at play remain largely unknown. We combine high-fidelity numerical simulations of multiple, self propelled swimmers with novel deep reinforcement learning algorithms to discover optimal ways for swimmers to interact with unsteady wakes, in a fully unsupervised manner. We identify optimal flow-interaction strategies devised by the resulting autonomous swimmers, and use it to formulate an effective control-logic. We demonstrate, via 3D simulations of controlled groups that swimmers exploiting the learned strategy exhibit a significant reduction in energy-expenditure. ERC Advanced Investigator Award 341117.

Magnetic Shocks and Substructures Excited by Torsional Alfvén Wave Interactions in Merging Expanding Flux Tubes

NASA Astrophysics Data System (ADS)

Snow, B.; Fedun, V.; Gent, F. A.; Verth, G.; Erdélyi, R.

2018-04-01

Vortex motions are frequently observed on the solar photosphere. These motions may play a key role in the transport of energy and momentum from the lower atmosphere into the upper solar atmosphere, contributing to coronal heating. The lower solar atmosphere also consists of complex networks of flux tubes that expand and merge throughout the chromosphere and upper atmosphere. We perform numerical simulations to investigate the behavior of vortex-driven waves propagating in a pair of such flux tubes in a non-force-free equilibrium with a realistically modeled solar atmosphere. The two flux tubes are independently perturbed at their footpoints by counter-rotating vortex motions. When the flux tubes merge, the vortex motions interact both linearly and nonlinearly. The linear interactions generate many small-scale transient magnetic substructures due to the magnetic stress imposed by the vortex motions. Thus, an initially monolithic tube is separated into a complex multithreaded tube due to the photospheric vortex motions. The wave interactions also drive a superposition that increases in amplitude until it exceeds the local Mach number and produces shocks that propagate upward with speeds of approximately 50 km s‑1. The shocks act as conduits transporting momentum and energy upward, and heating the local plasma by more than an order of magnitude, with a peak temperature of approximately 60,000 K. Therefore, we present a new mechanism for the generation of magnetic waveguides from the lower solar atmosphere to the solar corona. This wave guide appears as the result of interacting perturbations in neighboring flux tubes. Thus, the interactions of photospheric vortex motions is a potentially significant mechanism for energy transfer from the lower to upper solar atmosphere.

Discriminating Rigid from Nonrigid Motion

DTIC Science & Technology

1989-07-31

motion can be given a three-dimensional interpretation using a constraint of rigidity. Kruppa’s result and others (Faugeras & Maybank , 1989; Huang...Experimental Psychology: Human Perception and Performance, 10, 1-11. Faugeras, 0., & Maybank , S. (1989). Motion from point matches: multiplicity of

Multiple components in narrow planetary rings.

PubMed

Benet, L; Merlo, O

2008-01-11

The phase-space volume of regions of regular or trapped motion, for bounded or scattering systems with 2 degrees of freedom, respectively, displays universal properties. In particular, drastic reductions in the volume (gaps) are observed at specific values of a control parameter. Using the stability resonances we show that they, and not the mean-motion resonances, account for the position of these gaps. For more degrees of freedom, exciting these resonances divides the regions of trapped motion. For planetary rings, we demonstrate that this mechanism yields rings with multiple components.

Dynamic shared state maintenance in distributed virtual environments

NASA Astrophysics Data System (ADS)

Hamza-Lup, Felix George

Advances in computer networks and rendering systems facilitate the creation of distributed collaborative environments in which the distribution of information at remote locations allows efficient communication. Particularly challenging are distributed interactive Virtual Environments (VE) that allow knowledge sharing through 3D information. The purpose of this work is to address the problem of latency in distributed interactive VE and to develop a conceptual model for consistency maintenance in these environments based on the participant interaction model. An area that needs to be explored is the relationship between the dynamic shared state and the interaction with the virtual entities present in the shared scene. Mixed Reality (MR) and VR environments must bring the human participant interaction into the loop through a wide range of electronic motion sensors, and haptic devices. Part of the work presented here defines a novel criterion for categorization of distributed interactive VE and introduces, as well as analyzes, an adaptive synchronization algorithm for consistency maintenance in such environments. As part of the work, a distributed interactive Augmented Reality (AR) testbed and the algorithm implementation details are presented. Currently the testbed is part of several research efforts at the Optical Diagnostics and Applications Laboratory including 3D visualization applications using custom built head-mounted displays (HMDs) with optical motion tracking and a medical training prototype for endotracheal intubation and medical prognostics. An objective method using quaternion calculus is applied for the algorithm assessment. In spite of significant network latency, results show that the dynamic shared state can be maintained consistent at multiple remotely located sites. In further consideration of the latency problems and in the light of the current trends in interactive distributed VE applications, we propose a hybrid distributed system architecture for sensor-based distributed VE that has the potential to improve the system real-time behavior and scalability. (Abstract shortened by UMI.)

Non-Additive Increases in Sediment Stability Are Generated by Macroinvertebrate Species Interactions in Laboratory Streams

PubMed Central

Albertson, Lindsey K.; Cardinale, Bradley J.; Sklar, Leonard S.

2014-01-01

Previous studies have shown that biological structures such as plant roots can have large impacts on landscape morphodynamics, and that physical models that do not incorporate biology can generate qualitatively incorrect predictions of sediment transport. However, work to date has focused almost entirely on the impacts of single, usually dominant, species. Here we ask whether multiple, coexisting species of hydropsychid caddisfly larvae have different impacts on sediment mobility compared to single-species systems due to competitive interactions and niche differences. We manipulated the presence of two common species of net-spinning caddisfly (Ceratopsyche oslari, Arctopsyche californica) in laboratory mesocosms and measured how their silk filtration nets influence the critical shear stress required to initiate sediment grain motion when they were in monoculture versus polyculture. We found that critical shear stress increases non-additively in polycultures where species were allowed to interact. Critical shear stress was 26% higher in multi-species assemblages compared to the average single-species monoculture, and 21% greater than levels of stability achieved by the species having the largest impact on sediment motion in monoculture. Supplementary behavioral experiments suggest the non-additive increase in critical shear stress may have occurred as competition among species led to shifts in the spatial distribution of the two populations and complementary habitat use. To explore the implications of these results for field conditions, we used results from the laboratory study to parameterize a common model of sediment transport. We then used this model to estimate potential bed movement in a natural stream for which we had measurements of channel geometry, grain size, and daily discharge. Although this extrapolation is speculative, it illustrates that multi-species impacts could be sufficiently large to reduce bedload sediment flux over annual time scales in streams where multiple species of caddisfly are present. PMID:25101964

Dynamical simulation priors for human motion tracking.

PubMed

Vondrak, Marek; Sigal, Leonid; Jenkins, Odest Chadwicke

2013-01-01

We propose a simulation-based dynamical motion prior for tracking human motion from video in presence of physical ground-person interactions. Most tracking approaches to date have focused on efficient inference algorithms and/or learning of prior kinematic motion models; however, few can explicitly account for the physical plausibility of recovered motion. Here, we aim to recover physically plausible motion of a single articulated human subject. Toward this end, we propose a full-body 3D physical simulation-based prior that explicitly incorporates a model of human dynamics into the Bayesian filtering framework. We consider the motion of the subject to be generated by a feedback “control loop” in which Newtonian physics approximates the rigid-body motion dynamics of the human and the environment through the application and integration of interaction forces, motor forces, and gravity. Interaction forces prevent physically impossible hypotheses, enable more appropriate reactions to the environment (e.g., ground contacts), and are produced from detected human-environment collisions. Motor forces actuate the body, ensure that proposed pose transitions are physically feasible, and are generated using a motion controller. For efficient inference in the resulting high-dimensional state space, we utilize an exemplar-based control strategy that reduces the effective search space of motor forces. As a result, we are able to recover physically plausible motion of human subjects from monocular and multiview video. We show, both quantitatively and qualitatively, that our approach performs favorably with respect to Bayesian filtering methods with standard motion priors.

Parent-Child Talk about Motion: Links to Children's Development of Motion Event Language

ERIC Educational Resources Information Center

Hohenstein, Jill

2013-01-01

This study investigated the motion event language children and their parents engaged in while playing a board game. Children are sensitive to differences in manner and path at infancy, yet adult-like motion event expression appears relatively late in development. While multiple studies have examined how exposure to parent speech generally relates…

Micromagnetic analysis of current-induced domain wall motion in a bilayer nanowire with synthetic antiferromagnetic coupling

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

Komine, Takashi, E-mail: komine@mx.ibaraki.ac.jp; Aono, Tomosuke

We demonstrate current-induced domain wall motion in bilayer nanowire with synthetic antiferromagnetic (SAF) coupling by modeling two body problems for motion equations of domain wall. The influence of interlayer exchange coupling and magnetostatic interactions on current-induced domain wall motion in SAF nanowires was also investigated. By assuming the rigid wall model for translational motion, the interlayer exchange coupling and the magnetostatic interaction between walls and domains in SAF nanowires enhances domain wall speed without any spin-orbit-torque. The enhancement of domain wall speed was discussed by energy distribution as a function of wall angle configuration in bilayer nanowires.

Using Tracker to understand ‘toss up’ and free fall motion: a case study

NASA Astrophysics Data System (ADS)

Wee, Loo Kang; Kia Tan, Kim; Leong, Tze Kwang; Tan, Ching

2015-07-01

This paper reports the use of Tracker as a computer-based learning tool to support effective learning and teaching of ‘toss up’ and free fall motion for beginning secondary three (15 year-old) students. The case study involved (N = 123) students from express pure physics classes at a mainstream school in Singapore. We used eight multiple-choice questions pre- and post-test to gauge the impact on learning. The experimental group showed learning gains of d = 0.79  ±  0.23 (large effect) for Cohen’s d effect size analysis, and gains with a gradient of  total = 0.42  ±  0.08 (medium gain) above the traditional baseline value of  non interactive = 0.23 for Hake’s normalized gain regression analysis. This applied to all of the teachers and students who participated in this study. Our initial research findings suggest that allowing learners to relate abstract physics concepts to real life through coupling traditional video analysis with video modelling might be an innovative and effective method for teaching and learning about free fall motion.

Perception of Social Interactions for Spatially Scrambled Biological Motion

PubMed Central

Thurman, Steven M.; Lu, Hongjing

2014-01-01

It is vitally important for humans to detect living creatures in the environment and to analyze their behavior to facilitate action understanding and high-level social inference. The current study employed naturalistic point-light animations to examine the ability of human observers to spontaneously identify and discriminate socially interactive behaviors between two human agents. Specifically, we investigated the importance of global body form, intrinsic joint movements, extrinsic whole-body movements, and critically, the congruency between intrinsic and extrinsic motions. Motion congruency is hypothesized to be particularly important because of the constraint it imposes on naturalistic action due to the inherent causal relationship between limb movements and whole body motion. Using a free response paradigm in Experiment 1, we discovered that many naïve observers (55%) spontaneously attributed animate and/or social traits to spatially-scrambled displays of interpersonal interaction. Total stimulus motion energy was strongly correlated with the likelihood that an observer would attribute animate/social traits, as opposed to physical/mechanical traits, to the scrambled dot stimuli. In Experiment 2, we found that participants could identify interactions between spatially-scrambled displays of human dance as long as congruency was maintained between intrinsic/extrinsic movements. Violating the motion congruency constraint resulted in chance discrimination performance for the spatially-scrambled displays. Finally, Experiment 3 showed that scrambled point-light dancing animations violating this constraint were also rated as significantly less interactive than animations with congruent intrinsic/extrinsic motion. These results demonstrate the importance of intrinsic/extrinsic motion congruency for biological motion analysis, and support a theoretical framework in which early visual filters help to detect animate agents in the environment based on several fundamental constraints. Only after satisfying these basic constraints could stimuli be evaluated for high-level social content. In this way, we posit that perceptual animacy may serve as a gateway to higher-level processes that support action understanding and social inference. PMID:25406075

The SCEC Unified Community Velocity Model (UCVM) Software Framework for Distributing and Querying Seismic Velocity Models

NASA Astrophysics Data System (ADS)

Maechling, P. J.; Taborda, R.; Callaghan, S.; Shaw, J. H.; Plesch, A.; Olsen, K. B.; Jordan, T. H.; Goulet, C. A.

2017-12-01

Crustal seismic velocity models and datasets play a key role in regional three-dimensional numerical earthquake ground-motion simulation, full waveform tomography, modern physics-based probabilistic earthquake hazard analysis, as well as in other related fields including geophysics, seismology, and earthquake engineering. The standard material properties provided by a seismic velocity model are P- and S-wave velocities and density for any arbitrary point within the geographic volume for which the model is defined. Many seismic velocity models and datasets are constructed by synthesizing information from multiple sources and the resulting models are delivered to users in multiple file formats, such as text files, binary files, HDF-5 files, structured and unstructured grids, and through computer applications that allow for interactive querying of material properties. The Southern California Earthquake Center (SCEC) has developed the Unified Community Velocity Model (UCVM) software framework to facilitate the registration and distribution of existing and future seismic velocity models to the SCEC community. The UCVM software framework is designed to provide a standard query interface to multiple, alternative velocity models, even if the underlying velocity models are defined in different formats or use different geographic projections. The UCVM framework provides a comprehensive set of open-source tools for querying seismic velocity model properties, combining regional 3D models and 1D background models, visualizing 3D models, and generating computational models in the form of regular grids or unstructured meshes that can be used as inputs for ground-motion simulations. The UCVM framework helps researchers compare seismic velocity models and build equivalent simulation meshes from alternative velocity models. These capabilities enable researchers to evaluate the impact of alternative velocity models in ground-motion simulations and seismic hazard analysis applications. In this poster, we summarize the key components of the UCVM framework and describe the impact it has had in various computational geoscientific applications.

Self-evaluation on Motion Adaptation for Service Robots

NASA Astrophysics Data System (ADS)

Funabora, Yuki; Yano, Yoshikazu; Doki, Shinji; Okuma, Shigeru

We suggest self motion evaluation method to adapt to environmental changes for service robots. Several motions such as walking, dancing, demonstration and so on are described with time series patterns. These motions are optimized with the architecture of the robot and under certain surrounding environment. Under unknown operating environment, robots cannot accomplish their tasks. We propose autonomous motion generation techniques based on heuristic search with histories of internal sensor values. New motion patterns are explored under unknown operating environment based on self-evaluation. Robot has some prepared motions which realize the tasks under the designed environment. Internal sensor values observed under the designed environment with prepared motions show the interaction results with the environment. Self-evaluation is composed of difference of internal sensor values between designed environment and unknown operating environment. Proposed method modifies the motions to synchronize the interaction results on both environment. New motion patterns are generated to maximize self-evaluation function without external information, such as run length, global position of robot, human observation and so on. Experimental results show that the possibility to adapt autonomously patterned motions to environmental changes.

In-vehicle group activity modeling and simulation in sensor-based virtual environment

NASA Astrophysics Data System (ADS)

Shirkhodaie, Amir; Telagamsetti, Durga; Poshtyar, Azin; Chan, Alex; Hu, Shuowen

2016-05-01

Human group activity recognition is a very complex and challenging task, especially for Partially Observable Group Activities (POGA) that occur in confined spaces with limited visual observability and often under severe occultation. In this paper, we present IRIS Virtual Environment Simulation Model (VESM) for the modeling and simulation of dynamic POGA. More specifically, we address sensor-based modeling and simulation of a specific category of POGA, called In-Vehicle Group Activities (IVGA). In VESM, human-alike animated characters, called humanoids, are employed to simulate complex in-vehicle group activities within the confined space of a modeled vehicle. Each articulated humanoid is kinematically modeled with comparable physical attributes and appearances that are linkable to its human counterpart. Each humanoid exhibits harmonious full-body motion - simulating human-like gestures and postures, facial impressions, and hands motions for coordinated dexterity. VESM facilitates the creation of interactive scenarios consisting of multiple humanoids with different personalities and intentions, which are capable of performing complicated human activities within the confined space inside a typical vehicle. In this paper, we demonstrate the efficiency and effectiveness of VESM in terms of its capabilities to seamlessly generate time-synchronized, multi-source, and correlated imagery datasets of IVGA, which are useful for the training and testing of multi-source full-motion video processing and annotation. Furthermore, we demonstrate full-motion video processing of such simulated scenarios under different operational contextual constraints.

Interactive-rate Motion Planning for Concentric Tube Robots.

PubMed

Torres, Luis G; Baykal, Cenk; Alterovitz, Ron

2014-05-01

Concentric tube robots may enable new, safer minimally invasive surgical procedures by moving along curved paths to reach difficult-to-reach sites in a patient's anatomy. Operating these devices is challenging due to their complex, unintuitive kinematics and the need to avoid sensitive structures in the anatomy. In this paper, we present a motion planning method that computes collision-free motion plans for concentric tube robots at interactive rates. Our method's high speed enables a user to continuously and freely move the robot's tip while the motion planner ensures that the robot's shaft does not collide with any anatomical obstacles. Our approach uses a highly accurate mechanical model of tube interactions, which is important since small movements of the tip position may require large changes in the shape of the device's shaft. Our motion planner achieves its high speed and accuracy by combining offline precomputation of a collision-free roadmap with online position control. We demonstrate our interactive planner in a simulated neurosurgical scenario where a user guides the robot's tip through the environment while the robot automatically avoids collisions with the anatomical obstacles.

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

PubMed

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

2016-12-01

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

Motion control of the rabbit ankle joint with a flat interface nerve electrode.

PubMed

Park, Hyun-Joo; Durand, Dominique M

2015-12-01

A flat interface nerve electrode (FINE) has been shown to improve fascicular and subfascicular selectivity. A recently developed novel control algorithm for FINE was applied to motion control of the rabbit ankle. A 14-contact FINE was placed on the rabbit sciatic nerve (n = 8), and ankle joint motion was controlled for sinusoidal trajectories and filtered random trajectories. To this end, a real-time controller was implemented with a multiple-channel current stimulus isolator. The performance test results showed good tracking performance of rabbit ankle joint motion for filtered random trajectories and sinusoidal trajectories (0.5 Hz and 1.0 Hz) with <10% average root-mean-square (RMS) tracking error, whereas the average range of ankle joint motion was between -20.0 ± 9.3° and 18.1 ± 8.8°. The proposed control algorithm enables the use of a multiple-contact nerve electrode for motion trajectory tracking control of musculoskeletal systems. © 2015 Wiley Periodicals, Inc.

Scalable sensing electronics towards a motion capture suit

NASA Astrophysics Data System (ADS)

Xu, Daniel; Gisby, Todd A.; Xie, Shane; Anderson, Iain A.

2013-04-01

Being able to accurately record body motion allows complex movements to be characterised and studied. This is especially important in the film or sport coaching industry. Unfortunately, the human body has over 600 skeletal muscles, giving rise to multiple degrees of freedom. In order to accurately capture motion such as hand gestures, elbow or knee flexion and extension, vast numbers of sensors are required. Dielectric elastomer (DE) sensors are an emerging class of electroactive polymer (EAP) that is soft, lightweight and compliant. These characteristics are ideal for a motion capture suit. One challenge is to design sensing electronics that can simultaneously measure multiple sensors. This paper describes a scalable capacitive sensing device that can measure up to 8 different sensors with an update rate of 20Hz.

Motion and force control of multiple robotic manipulators

NASA Technical Reports Server (NTRS)

Wen, John T.; Kreutz-Delgado, Kenneth

1992-01-01

This paper addresses the motion and force control problem of multiple robot arms manipulating a cooperatively held object. A general control paradigm is introduced which decouples the motion and force control problems. For motion control, different control strategies are constructed based on the variables used as the control input in the controller design. There are three natural choices; acceleration of a generalized coordinate, arm tip force vectors, and the joint torques. The first two choices require full model information but produce simple models for the control design problem. The last choice results in a class of relatively model independent control laws by exploiting the Hamiltonian structure of the open loop system. The motion control only determines the joint torque to within a manifold, due to the multiple-arm kinematic constraint. To resolve the nonuniqueness of the joint torques, two methods are introduced. If the arm and object models are available, an optimization can be performed to best allocate the desired and effector control force to the joint actuators. The other possibility is to control the internal force about some set point. It is shown that effective force regulation can be achieved even if little model information is available.

The Effects of Using the Kinect Motion-Sensing Interactive System to Enhance English Learning for Elementary Students

ERIC Educational Resources Information Center

Pan, Wen Fu

2017-01-01

The objective of this study was to test whether the Kinect motion-sensing interactive system (KMIS) enhanced students' English vocabulary learning, while also comparing the system's effectiveness against a traditional computer-mouse interface. Both interfaces utilized an interactive game with a questioning strategy. One-hundred and twenty…

An involuntary stereotypical grasp tendency pervades voluntary dynamic multifinger manipulation

PubMed Central

Rácz, Kornelius; Brown, Daniel

2012-01-01

We used a novel apparatus with three hinged finger pads to characterize collaborative multifinger interactions during dynamic manipulation requiring individuated control of fingertip motions and forces. Subjects placed the thumb, index, and middle fingertips on each hinged finger pad and held it—unsupported—with constant total grasp force while voluntarily oscillating the thumb's pad. This task combines the need to 1) hold the object against gravity while 2) dynamically reconfiguring the grasp. Fingertip force variability in this combined motion and force task exhibited strong synchrony among normal (i.e., grasp) forces. Mechanical analysis and simulation show that such synchronous variability is unnecessary and cannot be explained solely by signal-dependent noise. Surprisingly, such variability also pervaded control tasks requiring different individuated fingertip motions and forces, but not tasks without finger individuation such as static grasp. These results critically extend notions of finger force variability by exposing and quantifying a pervasive challenge to dynamic multifinger manipulation: the need for the neural controller to carefully and continuously overlay individuated finger actions over mechanically unnecessary synchronous interactions. This is compatible with—and may explain—the phenomenology of strong coupling of hand muscles when this delicate balance is not yet developed, as in early childhood, or when disrupted, as in brain injury. We conclude that the control of healthy multifinger dynamic manipulation has barely enough neuromechanical degrees of freedom to meet the multiple demands of ecological tasks and critically depends on the continuous inhibition of synchronous grasp tendencies, which we speculate may be of vestigial evolutionary origin. PMID:22956798

Space adaptation syndrome: multiple etiological factors and individual differences

NASA Technical Reports Server (NTRS)

Lackner, J. R.; DiZio, P.

1991-01-01

Space motion sickness is a significant operational concern in the American and Soviet space programs. Nearly 70% of all astronauts and cosmonauts are affected to some degree during their first several days of flight. It is now beginning to appear that space motion sickness like terrestrial motion sickness is the consequence of multiple etiological factors. As we come to understand basic mechanisms of spatial orientation and sensory-motor adaptation we can begin to predict etiological factors in different motion environments. Individuals vary greatly in the extent to which they are susceptible to these different factors. However, individuals seem to be relatively self-consistent in terms of their rates of adaptation to provocative stimulation and their retention of adaptation. Attempts to relate susceptibility to motion sickness during the microgravity phases of parabolic flight maneuvers to vestibular function under 1G and 0G test conditions are described.

Self-Paced Physics, Segment 18.

ERIC Educational Resources Information Center

New York Inst. of Tech., Old Westbury.

Eighty-seven problems are included in this volume which is arranged to match study segments 2 through 14. The subject matter is related to projectiles, simple harmonic motion, kinetic friction, multiple pulley arrangements, motion on inclined planes, circular motion, potential energy, kinetic energy, center of mass, Newton's laws, elastic and…

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

Kennedy, R.P.; Kincaid, R.H.; Short, S.A.

This report presents the results of part of a two-task study on the engineering characterization of earthquake ground motion for nuclear power plant design. Task I of the study, which is presented in NUREG/CR-3805, Vol. 1, developed a basis for selecting design response spectra taking into account the characteristics of free-field ground motion found to be significant in causing structural damage. Task II incorporates additional considerations of effects of spatial variations of ground motions and soil-structure interaction on foundation motions and structural response. The results of Task II are presented in four parts: (1) effects of ground motion characteristics onmore » structural response of a typical PWR reactor building with localized nonlinearities and soil-structure interaction effects; (2) empirical data on spatial variations of earthquake ground motion; (3) soil-structure interaction effects on structural response; and (4) summary of conclusions and recommendations based on Tasks I and II studies. This report presents the results of the first part of Task II. The results of the other parts will be presented in NUREG/CR-3805, Vols. 3 to 5.« less

Two motion systems with common and separate pathways for color and luminance.

PubMed Central

Gorea, A; Papathomas, T V; Kovacs, I

1993-01-01

We present psychological experiments that reveal two motion systems, a specific and an unspecific one. The specific system prevails at medium to high temporal frequencies. It comprises at least two separate motion pathways that are selective for color and for luminance and that do not interact until after the motion signal is extracted separately in each. By contrast, the unspecific system prevails at low temporal frequencies and it combines color and luminance signals at an earlier stage, before motion extraction. The successful implementation of an efficient and accurate technique for assessing equiluminance corroborates further the main findings. These results offer a general framework for understanding the nature of interactions between color and luminance signals in motion perception and suggest that previously proposed dichotomies in motion processing may be encompassed by the specific/unspecific dichotomy proposed here. Images Fig. 2 Fig. 4 PMID:8248227

Spontaneous oscillation and fluid-structure interaction of cilia.

PubMed

Han, Jihun; Peskin, Charles S

2018-04-24

The exact mechanism to orchestrate the action of hundreds of dynein motor proteins to generate wave-like ciliary beating remains puzzling and has fascinated many scientists. We present a 3D model of a cilium and the simulation of its beating in a fluid environment. The model cilium obeys a simple geometric constraint that arises naturally from the microscopic structure of a real cilium. This constraint allows us to determine the whole 3D structure at any instant in terms of the configuration of a single space curve. The tensions of active links, which model the dynein motor proteins, follow a postulated dynamical law, and together with the passive elasticity of microtubules, this dynamical law is responsible for the ciliary motions. In particular, our postulated tension dynamics lead to the instability of a symmetrical steady state, in which the cilium is straight and its active links are under equal tensions. The result of this instability is a stable, wave-like, limit cycle oscillation. We have also investigated the fluid-structure interaction of cilia using the immersed boundary (IB) method. In this setting, we see not only coordination within a single cilium but also, coordinated motion, in which multiple cilia in an array organize their beating to pump fluid, in particular by breaking phase synchronization.

Manual therapy in osteoarthritis of the hip: outcome in subgroups of patients.

PubMed

Hoeksma, H L; Dekker, J; Ronday, H K; Breedveld, F C; Van den Ende, C H M

2005-04-01

To investigate whether manual therapy has particular benefit in subgroups of patients defined on the basis of hip function, range of joint motion, pain and radiological deterioration. The study was performed in the out-patient clinic of physical therapy of a large hospital. Data on 109 patients with OA of the hip (clinical ACR criteria) participating in a randomized clinical trial on the effects of manual therapy were used. The outcomes for hip function (Harris hip score), range of joint motion (ROM) and pain (VAS) were compared for specific subgroups. Subgroups were assigned by the median split method. The interaction effect between subgroup and treatment was tested using multiple regression analysis. No differences were observed in the effect of manual therapy in specific subgroups of patients defined on the basis of baseline levels of hip function, pain and ROM. On the basis of radiological grading of osteoarthritis (OA), we found that patients with severe radiological grading of OA had significantly worse outcome on ROM as a result of manual therapy than patients with mild or moderate radiological grading of OA. A significant interaction effect was found for only 1 out of 12 hypotheses investigated. Therefore, we conclude that there is no evidence for the particular benefit of manual therapy in subgroups of patients.

Metabolic networks in motion: 13C-based flux analysis

PubMed Central

Sauer, Uwe

2006-01-01

Many properties of complex networks cannot be understood from monitoring the components—not even when comprehensively monitoring all protein or metabolite concentrations—unless such information is connected and integrated through mathematical models. The reason is that static component concentrations, albeit extremely informative, do not contain functional information per se. The functional behavior of a network emerges only through the nonlinear gene, protein, and metabolite interactions across multiple metabolic and regulatory layers. I argue here that intracellular reaction rates are the functional end points of these interactions in metabolic networks, hence are highly relevant for systems biology. Methods for experimental determination of metabolic fluxes differ fundamentally from component concentration measurements; that is, intracellular reaction rates cannot be detected directly, but must be estimated through computer model-based interpretation of stable isotope patterns in products of metabolism. PMID:17102807

Project Physics Tests 1, Concepts of Motion.

ERIC Educational Resources Information Center

Harvard Univ., Cambridge, MA. Harvard Project Physics.

Test items relating to Project Physics Unit 1 are presented in this booklet, consisting of 70 multiple-choice and 20 problem-and-essay questions. Concepts of motion are examined with respect to velocities, acceleration, forces, vectors, Newton's laws, and circular motion. Suggestions are made for time consumption in answering some items. Besides…

Discovery Learning, Representation, and Explanation within a Computer-Based Simulation: Finding the Right Mix

ERIC Educational Resources Information Center

Rieber, Lloyd P.; Tzeng, Shyh-Chii; Tribble, Kelly

2004-01-01

The purpose of this research was to explore how adult users interact and learn during an interactive computer-based simulation supplemented with brief multimedia explanations of the content. A total of 52 college students interacted with a computer-based simulation of Newton's laws of motion in which they had control over the motion of a simple…

The Effectiveness of Using Interactive Multimedia in Improving the Concept of Fashion Design and Its Application in The Making of Digital Fashion Design

NASA Astrophysics Data System (ADS)

Wiana, W.

2018-02-01

This research is related to the effort to design a more representative learning system to improve the learning result of digital fashion design, through the development of interactive multimedia based on motion graphic. This research is aimed to know the effect of interactive multimedia application based on motion graphic to increase the mastery of the concept and skill of the students to making fashion designing in digital format. The research method used is quasi experiment with research design of Non-equivalent Control Group Design. The lectures are conducted in two different classes, namely class A as the Experimental Class and class B as the Control Class. From the calculation result after interpreted using Normalize Gain, there is an increase of higher learning result in student with interactive learning based on motion graphic, compared with student achievement on conventional learning. In this research, interactive multimedia learning based on motion graphic is effective toward the improvement of student learning in concept mastering indicator and on the aspect of making fashion design in digital format.

Analysis of the Multiple-Solution Response of a Flexible Rotor Supported on Non-Linear Squeeze Film Dampers

NASA Astrophysics Data System (ADS)

ZHU, C. S.; ROBB, D. A.; EWINS, D. J.

2002-05-01

The multiple-solution response of rotors supported on squeeze film dampers is a typical non-linear phenomenon. The behaviour of the multiple-solution response in a flexible rotor supported on two identical squeeze film dampers with centralizing springs is studied by three methods: synchronous circular centred-orbit motion solution, numerical integration method and slow acceleration method using the assumption of a short bearing and cavitated oil film; the differences of computational results obtained by the three different methods are compared in this paper. It is shown that there are three basic forms for the multiple-solution response in the flexible rotor system supported on the squeeze film dampers, which are the resonant, isolated bifurcation and swallowtail bifurcation multiple solutions. In the multiple-solution speed regions, the rotor motion may be subsynchronous, super-subsynchronous, almost-periodic and even chaotic, besides synchronous circular centred, even if the gravity effect is not considered. The assumption of synchronous circular centred-orbit motion for the journal and rotor around the static deflection line can be used only in some special cases; the steady state numerical integration method is very useful, but time consuming. Using the slow acceleration method, not only can the multiple-solution speed regions be detected, but also the non-synchronous response regions.

The Motion and Control of a Chaplygin Sleigh with Internal Shape in an Ideal Fluid

NASA Astrophysics Data System (ADS)

Barot, Christopher

In this dissertation we will examine a nonholonomic system with Lie group symmetry: the Chaplygin sleigh coupled to an oscillator moving through a potential fluid in two dimensions. This example is chosen to illustrate several general features. The sleigh system in the plane has SE(2) symmetry. This group symmetry will be used to separate the dynamics of the system into those along the group directions and those not. The oscillator motion is not along the group and so acts as an additional configuration space coordinate that plays the role of internal "shape". The potential fluid serves as an interactive environment for the sleigh. The interaction between the fluid and sleigh depends not only on the sleigh body shape and size but also on its motion. The motion of the sleigh causes motion in the surrounding fluid and vice-versa. Since the sleigh body is coupled to the oscillator, the oscillator will have indirect interaction with the fluid. This oscillator serves as internal shape and interacts with the external environment of the sleigh through its coupling to the sleigh body and the nonholonomic constraint; it will be shown that this interaction can produce a variety of types of motion depending on the sleigh geometry. In particular, when the internal shape of the system is actively controlled, it will be proven that the sleigh can be steered through the plane towards any desired position. In this way the sleigh-fluid-oscillator system will demonstrate how a rigid body can be steered through an interactive environment by controlling things wholly within the body itself and without use of external thrust.

Validity of an ankle joint motion and position sense measurement system and its application in healthy subjects and patients with ankle sprain.

PubMed

Lin, Chueh-Ho; Chiang, Shang-Lin; Lu, Liang-Hsuan; Wei, Shun-Hwa; Sung, Wen-Hsu

2016-07-01

Ankle motion and proprioception in multiple axis movements are crucial for daily activities. However, few studies have developed and used a multiple axis system for measuring ankle motion and proprioception. This study was designed to validate a novel ankle haptic interface system that measures the ankle range of motion (ROM) and joint position sense in multiple plane movements, investigating the proprioception deficits during joint position sense tasks for patients with ankle instability. Eleven healthy adults (mean ± standard deviation; age, 24.7 ± 1.9 years) and thirteen patients with ankle instability were recruited in this study. All subjects were asked to perform tests to evaluate the validity of the ankle ROM measurements and underwent tests for validating the joint position sense measurements conducted during multiple axis movements of the ankle joint. Pearson correlation was used for validating the angular position measurements obtained using the developed system; the independent t test was used to investigate the differences in joint position sense task performance for people with or without ankle instability. The ROM measurements of the device were linearly correlated with the criterion standards (r = 0.99). The ankle instability and healthy groups were significantly different in direction, absolute, and variable errors of plantar flexion, dorsiflexion, inversion, and eversion (p < 0.05). The results demonstrate that the novel ankle joint motion and position sense measurement system is valid and can be used for measuring the ankle ROM and joint position sense in multiple planes and indicate proprioception deficits for people with ankle instability. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Self-motion impairs multiple-object tracking.

PubMed

Thomas, Laura E; Seiffert, Adriane E

2010-10-01

Investigations of multiple-object tracking aim to further our understanding of how people perform common activities such as driving in traffic. However, tracking tasks in the laboratory have overlooked a crucial component of much real-world object tracking: self-motion. We investigated the hypothesis that keeping track of one's own movement impairs the ability to keep track of other moving objects. Participants attempted to track multiple targets while either moving around the tracking area or remaining in a fixed location. Participants' tracking performance was impaired when they moved to a new location during tracking, even when they were passively moved and when they did not see a shift in viewpoint. Self-motion impaired multiple-object tracking in both an immersive virtual environment and a real-world analog, but did not interfere with a difficult non-spatial tracking task. These results suggest that people use a common mechanism to track changes both to the location of moving objects around them and to keep track of their own location. Copyright 2010 Elsevier B.V. All rights reserved.

Free Surface Wave Interaction with a Horizontal Cylinder

NASA Astrophysics Data System (ADS)

Oshkai, P.; Rockwell, D.

1999-10-01

Classes of vortex formation from a horizontal cylinder adjacent to an undulating free-surface wave are characterized using high-image-density particle image velocimetry. Instantaneous representations of the velocity field, streamline topology and vorticity patterns yield insight into the origin of unsteady loading of the cylinder. For sufficiently deep submergence of the cylinder, the orbital nature of the wave motion results in multiple sites of vortex development, i.e., onset of vorticity concentrations, along the surface of the cylinder, followed by distinctive types of shedding from the cylinder. All of these concentrations of vorticity then exhibit orbital motion about the cylinder. Their contributions to the instantaneous values of the force coefficients are assessed by calculating moments of vorticity. It is shown that large contributions to the moments and their rate of change with time can occur for those vorticity concentrations having relatively small amplitude orbital trajectories. In a limiting case, collision with the surface of the cylinder can occur. Such vortex-cylinder interactions exhibit abrupt changes in the streamline topology during the wave cycle, including abrupt switching of the location of saddle points in the wave. The effect of nominal depth of submergence of the cylinder is characterized in terms of the time history of patterns of vorticity generated from the cylinder and the free surface. Generally speaking, generic types of vorticity concentrations are formed from the cylinder during the cycle of the wave motion for all values of submergence. The proximity of the free surface, however, can exert a remarkable influence on the initial formation, the eventual strength, and the subsequent motion of concentrations of vorticity. For sufficiently shallow submergence, large-scale vortex formation from the upper surface of the cylinder is inhibited and, in contrast, that from the lower surface of the cylinder is intensified. Moreover, decreasing the depth of submergence retards the orbital migration of previously shed concentrations of vorticity about the cylinder.

Reconstructing Plate Motions on Europa with GPlates

NASA Astrophysics Data System (ADS)

Cutler, B. B.; Collins, G. C.; Prockter, L. M.; Patterson, G.; Kattenhorn, S. A.; Rhoden, A.; Cooper, C. M.

2015-12-01

Observations of past plate tectonic - like motions in Europa's icy lithosphere have been reported in previous studies. Quantifying the nature, age, and amount of plate motion is important for geophysical models of Europa's ice shell and for astrobiology, since subsumed pates could drive the flow of nutrients into the subsurface ocean. We have used GPlates software (Williams et al., GSA Today 2012) and a mosaic of regional-resolution Galileo SSI data from orbits E11, E15, E17, and E19 to make interactive reconstructions of both the Northern Falga region (60N, 220W) and the Castalia Macula region (0N, 225W). The advantage of this method is that plate motions are calculated on a sphere, while still maintaining the original Galileo image pieces in their proper geographic locations. Previous work on the Castalia Macula region (Patterson et al. J.Struct.Geol. 2006) and the adjacent Phaidra Linea region (Patterson and Ernst, LPSC 2011) found offsets along spreading boundaries, and then calculated the best fit finite rotations to close those offsets. Though this method is mathematically rigorous and gives a statistical goodness of fit, it is not easy to test multiple hypotheses for candidate piercing points or divisions of candidate plate boundaries. Through the interactive environment, we found that we could better account for observed offsets in this region by breaking it into 32 different plates. Patterson and Ernst broke the Phaidra region into 6 plates which exhibited nonrigid behavior, where our study breaks it into 16 rigid plates. The Northern Falga Regio area is interesting due to the potential for large amounts of subsumption of Europa's icy crust in this location. The previous reconstruction (Kattenhorn and Prockter, Nat.Geosci. 2014) was based on planar geometry, and we have replicated these results using a spherically-based reconstruction. We will present the plate maps and reconstructions for both of these regions, along with the best fit rotation poles.

Second-chance signal transduction explains cooperative flagellar switching.

PubMed

Zot, Henry G; Hasbun, Javier E; Minh, Nguyen Van

2012-01-01

The reversal of flagellar motion (switching) results from the interaction between a switch complex of the flagellar rotor and a torque-generating stationary unit, or stator (motor unit). To explain the steeply cooperative ligand-induced switching, present models propose allosteric interactions between subunits of the rotor, but do not address the possibility of a reaction that stimulates a bidirectional motor unit to reverse direction of torque. During flagellar motion, the binding of a ligand-bound switch complex at the dwell site could excite a motor unit. The probability that another switch complex of the rotor, moving according to steady-state rotation, will reach the same dwell site before that motor unit returns to ground state will be determined by the independent decay rate of the excited-state motor unit. Here, we derive an analytical expression for the energy coupling between a switch complex and a motor unit of the stator complex of a flagellum, and demonstrate that this model accounts for the cooperative switching response without the need for allosteric interactions. The analytical result can be reproduced by simulation when (1) the motion of the rotor delivers a subsequent ligand-bound switch to the excited motor unit, thereby providing the excited motor unit with a second chance to remain excited, and (2) the outputs from multiple independent motor units are constrained to a single all-or-none event. In this proposed model, a motor unit and switch complex represent the components of a mathematically defined signal transduction mechanism in which energy coupling is driven by steady-state and is regulated by stochastic ligand binding. Mathematical derivation of the model shows the analytical function to be a general form of the Hill equation (Hill AV (1910) The possible effects of the aggregation of the molecules of haemoglobin on its dissociation curves. J Physiol 40: iv-vii).

Interactive-rate Motion Planning for Concentric Tube Robots

PubMed Central

Torres, Luis G.; Baykal, Cenk; Alterovitz, Ron

2014-01-01

Concentric tube robots may enable new, safer minimally invasive surgical procedures by moving along curved paths to reach difficult-to-reach sites in a patient’s anatomy. Operating these devices is challenging due to their complex, unintuitive kinematics and the need to avoid sensitive structures in the anatomy. In this paper, we present a motion planning method that computes collision-free motion plans for concentric tube robots at interactive rates. Our method’s high speed enables a user to continuously and freely move the robot’s tip while the motion planner ensures that the robot’s shaft does not collide with any anatomical obstacles. Our approach uses a highly accurate mechanical model of tube interactions, which is important since small movements of the tip position may require large changes in the shape of the device’s shaft. Our motion planner achieves its high speed and accuracy by combining offline precomputation of a collision-free roadmap with online position control. We demonstrate our interactive planner in a simulated neurosurgical scenario where a user guides the robot’s tip through the environment while the robot automatically avoids collisions with the anatomical obstacles. PMID:25436176

Stepwise Adaptations to Low Temperature as Revealed by Multiple Mutants of Psychrophilic α-Amylase from Antarctic Bacterium*

PubMed Central

Cipolla, Alexandre; D'Amico, Salvino; Barumandzadeh, Roya; Matagne, André; Feller, Georges

2011-01-01

The mutants Mut5 and Mut5CC from a psychrophilic α-amylase bear representative stabilizing interactions found in the heat-stable porcine pancreatic α-amylase but lacking in the cold-active enzyme from an Antarctic bacterium. From an evolutionary perspective, these mutants can be regarded as structural intermediates between the psychrophilic and the mesophilic enzymes. We found that these engineered interactions improve all the investigated parameters related to protein stability as follows: compactness; kinetically driven stability; thermodynamic stability; resistance toward chemical denaturation, and the kinetics of unfolding/refolding. Concomitantly to this improved stability, both mutants have lost the kinetic optimization to low temperature activity displayed by the parent psychrophilic enzyme. These results provide strong experimental support to the hypothesis assuming that the disappearance of stabilizing interactions in psychrophilic enzymes increases the amplitude of concerted motions required by catalysis and the dynamics of active site residues at low temperature, leading to a higher activity. PMID:21900238

Multiple Near Wake Patterns Behind Annular Rings

NASA Astrophysics Data System (ADS)

Zhang, Jinzhong; Higuchi, Hiroshi; Muzas, Brian K.; Furuya, Shojiro

1996-11-01

Wake interactions behind concentric annular rings at different spacing ratios were experimentally investigated. The flow visualization, laser Doppler velocimetry data and results from the particle tracking velocimetry are presented and discussed. Jets through individual slots merged in multiply-stable, axisymmetric manners. Most flow patterns were persistent unless the flow was strongly disturbed. The vortex interactions from individual annular elements were also axisymmetric in the near wake. This is in contrast to the asymmetric flows observed earlier behind two-dimensional slotted plates (Higuchi et al. J. Aircraft 26 1989, Phys. Fluids 6(1), 1994). The intermediate wake, however, was dominated by large scale, three-dimensional wake motions even at moderate porosity. Onset of the specific flow patterns was associated with the interactions among start-up vortices. Given model geometry, different turbulent structures and mean velocity profiles were observed in the intermediate wake depending on the near wake pattern. *BKM was a NSF-REU Program undergrad. from Princeton U. and SF was from Mitsubishi Heavy Industries. This work was suppoted in part by the Naval Air Warfare Center.

Local discretization method for overdamped Brownian motion on a potential with multiple deep wells.

PubMed

Nguyen, P T T; Challis, K J; Jack, M W

2016-11-01

We present a general method for transforming the continuous diffusion equation describing overdamped Brownian motion on a time-independent potential with multiple deep wells to a discrete master equation. The method is based on an expansion in localized basis states of local metastable potentials that match the full potential in the region of each potential well. Unlike previous basis methods for discretizing Brownian motion on a potential, this approach is valid for periodic potentials with varying multiple deep wells per period and can also be applied to nonperiodic systems. We apply the method to a range of potentials and find that potential wells that are deep compared to five times the thermal energy can be associated with a discrete localized state while shallower wells are better incorporated into the local metastable potentials of neighboring deep potential wells.

Local discretization method for overdamped Brownian motion on a potential with multiple deep wells

NASA Astrophysics Data System (ADS)

Nguyen, P. T. T.; Challis, K. J.; Jack, M. W.

2016-11-01

We present a general method for transforming the continuous diffusion equation describing overdamped Brownian motion on a time-independent potential with multiple deep wells to a discrete master equation. The method is based on an expansion in localized basis states of local metastable potentials that match the full potential in the region of each potential well. Unlike previous basis methods for discretizing Brownian motion on a potential, this approach is valid for periodic potentials with varying multiple deep wells per period and can also be applied to nonperiodic systems. We apply the method to a range of potentials and find that potential wells that are deep compared to five times the thermal energy can be associated with a discrete localized state while shallower wells are better incorporated into the local metastable potentials of neighboring deep potential wells.

Freestanding Triboelectric Nanogenerator Enables Noncontact Motion-Tracking and Positioning.

PubMed

Guo, Huijuan; Jia, Xueting; Liu, Lue; Cao, Xia; Wang, Ning; Wang, Zhong Lin

2018-04-24

Recent development of interactive motion-tracking and positioning technologies is attracting increasing interests in many areas, such as wearable electronics, intelligent electronics, and the internet of things. For example, the so-called somatosensory technology can afford users strong empathy of immersion and realism due to their consistent interaction with the game. Here, we report a noncontact self-powered positioning and motion-tracking system based on a freestanding triboelectric nanogenerator (TENG). The TENG was fabricated by a nanoengineered surface in the contact-separation mode with the use of a free moving human body (hands or feet) as the trigger. The poly(tetrafluoroethylene) (PTFE) arrays based interactive interface can give an output of 222 V from casual human motions. Different from previous works, this device also responses to a small action at certain heights of 0.01-0.11 m from the device with a sensitivity of about 315 V·m -1 , so that the mechanical sensing is possible. Such a distinctive noncontact sensing feature promotes a wide range of potential applications in smart interaction systems.

Contact angle hysteresis and motion behaviors of a water nano-droplet on suspended graphene under temperature gradient

NASA Astrophysics Data System (ADS)

Foroutan, Masumeh; Fatemi, S. Mahmood; Esmaeilian, Farshad; Fadaei Naeini, Vahid; Baniassadi, Majid

2018-05-01

In the present work, the effect of temperature gradient on the behavior of a water nano-droplet resting on a suspended graphene was studied based on a non-equilibrium molecular dynamics simulation. The acquired results indicate that the applied temperature gradient to the suspended graphene drives the water nano-droplet to the colder region. The droplet accelerates its motion toward the cold reservoir as the temperature gradient is increased. In addition to the translational motion of the nano-droplet, the vortical motion of the water molecules was also observed. Contact angle analysis was also utilized to describe the directional motion of the nano-droplet. The translational motion of the droplet leads to the estimation of contact angle hysteresis through advancing and receding contact angles while the rotational motion resulted in the advancing and receding fronts being switched with one another through the simulation. The average displacement vector of the water molecules shows that parts of the droplet seem to stagnate while other parts rotate around them. The reason behind this particular behavior was studied based on interaction energy contours between a water molecule and the suspended graphene. The obtained data indicate that the rotational motion is in agreement with the migration of the water molecules to low interaction energy regions in order to avoid high interaction energy areas.

Ligand Binding: Molecular Mechanics Calculation of the Streptavidin-Biotin Rupture Force

NASA Astrophysics Data System (ADS)

Grubmuller, Helmut; Heymann, Berthold; Tavan, Paul

1996-02-01

The force required to rupture the streptavidin-biotin complex was calculated here by computer simulations. The computed force agrees well with that obtained by recent single molecule atomic force microscope experiments. These simulations suggest a detailed multiple-pathway rupture mechanism involving five major unbinding steps. Binding forces and specificity are attributed to a hydrogen bond network between the biotin ligand and residues within the binding pocket of streptavidin. During rupture, additional water bridges substantially enhance the stability of the complex and even dominate the binding inter-actions. In contrast, steric restraints do not appear to contribute to the binding forces, although conformational motions were observed.

Brownian motion of classical spins: Anomalous dissipation and generalized Langevin equation

NASA Astrophysics Data System (ADS)

Bandyopadhyay, Malay; Jayannavar, A. M.

2017-10-01

In this work, we derive the Langevin equation (LE) of a classical spin interacting with a heat bath through momentum variables, starting from the fully dynamical Hamiltonian description. The derived LE with anomalous dissipation is analyzed in detail. The obtained LE is non-Markovian with multiplicative noise terms. The concomitant dissipative terms obey the fluctuation-dissipation theorem. The Markovian limit correctly produces the Kubo and Hashitsume equation. The perturbative treatment of our equations produces the Landau-Lifshitz equation and the Seshadri-Lindenberg equation. Then we derive the Fokker-Planck equation corresponding to LE and the concept of equilibrium probability distribution is analyzed.

Jet Stability and the Generation of Superluminal and Stationary Components

NASA Technical Reports Server (NTRS)

Agudo, Ivan; Gomez, Jose-Luis; Marti, Jose-Maria; Ibanez, Jose-Maria; Marscher, Alan P.; Alberdi, Antonio; Aloy, Miguel-Angel; Hardee, Philip E.

2001-01-01

We present a numerical simulation of the response of an expanding relativistic jet to the ejection of a superluminal component. The simulation has been performed with a relativistic time-dependent hydrodynamical code from which simulated radio maps are computed by integrating the transfer equations for synchrotron radiation. The interaction of the superluminal component with the underlying jet results in the formation of multiple conical shocks behind the main perturbation. These trailing components can be easily distinguished because they appear to be released from the primary superluminal component instead of being ejected from the core. Their oblique nature should also result in distinct polarization properties. Those appearing closer to the core show small apparent motions and a very slow secular decrease in brightness and could be identified as stationary components. Those appearing farther downstream are weaker and can reach superluminal apparent motions. The existence of these trailing components indicates that not all observed components necessarily represent major perturbations at the jet inlet; rather, multiple emission components can be generated by a single disturbance in the jet. While the superluminal component associated with the primary perturbation exhibits a rather stable pattern speed, trailing components have velocities that increase with distance from the core but move at less than the jet speed. The trailing components exhibit motion and structure consistent with the triggering of pinch modes by the superluminal component. The increase in velocity of the trailing components is an indirect consequence of the acceleration of the expanding fluid, which is assumed to be relativistically hot; if observed, such accelerations would therefore favor an electron-positron (as opposed to proton rest mass) dominated jet.

The Bagnold Dunes in Southern Summer: Active Sediment Transport on Mars Observed by the Curiosity rover

NASA Astrophysics Data System (ADS)

Baker, M. M.; Lapotre, M. G. A.; Bridges, N. T.; Minitti, M. E.; Newman, C. E.; Ehlmann, B. L.; Vasavada, A. R.; Edgett, K. S.; Lewis, K. W.

2017-12-01

Since its landing at Gale crater five years ago, the Curiosity rover has provided us with unparalleled data to study active surface processes on Mars. Repeat imaging campaigns (i.e. "change-detection campaigns") conducted with the rover's cameras have allowed us to study Martian atmosphere-surface interactions and characterize wind-driven sediment transport from ground-truth observations. Utilizing the rover's periodic stops to image identical patches of ground over multiple sols, these change-detection campaigns have revealed sediment motion over a wide range of grain sizes. These results have been corroborated in images taken by the rover's hand lens imager (MAHLI), which have captured sand transport occurring on the scale of minutes. Of particular interest are images collected during Curiosity's traverse across the Bagnold Dune Field, the first dune field observed to be active in situ on another planet. Curiosity carried out the first phase of the Bagnold Dunes campaign (between Ls 72º and 109º) along the northern edge of the dune field at the base of Aeolis Mons, where change-detection images showed very limited sediment motion. More recently, a second phase of the campaign was conducted along the southern edge of the dune field between Ls 312º to 345º; here, images captured extensive wind-driven sand motion. Observations from multiple cameras show ripples migrating to the southwest, in agreement with predicted net transport within the dune field. Together with change-detection observations conducted outside of the dune field, the data show that ubiquitous Martian landscapes are seasonally active within Gale crater, with the bulk of the sediment flux occurring during southern summer.

Emergence of macroscopic directed motion in populations of motile colloids

NASA Astrophysics Data System (ADS)

Bricard, Antoine; Caussin, Jean-Baptiste; Desreumaux, Nicolas; Dauchot, Olivier; Bartolo, Denis

2013-11-01

From the formation of animal flocks to the emergence of coordinated motion in bacterial swarms, populations of motile organisms at all scales display coherent collective motion. This consistent behaviour strongly contrasts with the difference in communication abilities between the individuals. On the basis of this universal feature, it has been proposed that alignment rules at the individual level could solely account for the emergence of unidirectional motion at the group level. This hypothesis has been supported by agent-based simulations. However, more complex collective behaviours have been systematically found in experiments, including the formation of vortices, fluctuating swarms, clustering and swirling. All these (living and man-made) model systems (bacteria, biofilaments and molecular motors, shaken grains and reactive colloids) predominantly rely on actual collisions to generate collective motion. As a result, the potential local alignment rules are entangled with more complex, and often unknown, interactions. The large-scale behaviour of the populations therefore strongly depends on these uncontrolled microscopic couplings, which are extremely challenging to measure and describe theoretically. Here we report that dilute populations of millions of colloidal rolling particles self-organize to achieve coherent motion in a unique direction, with very few density and velocity fluctuations. Quantitatively identifying the microscopic interactions between the rollers allows a theoretical description of this polar-liquid state. Comparison of the theory with experiment suggests that hydrodynamic interactions promote the emergence of collective motion either in the form of a single macroscopic `flock', at low densities, or in that of a homogenous polar phase, at higher densities. Furthermore, hydrodynamics protects the polar-liquid state from the giant density fluctuations that were hitherto considered the hallmark of populations of self-propelled particles. Our experiments demonstrate that genuine physical interactions at the individual level are sufficient to set homogeneous active populations into stable directed motion.

Perceptual and categorical decision making: goal-relevant representation of two domains at different levels of abstraction.

PubMed

Shankar, Swetha; Kayser, Andrew S

2017-06-01

To date it has been unclear whether perceptual decision making and rule-based categorization reflect activation of similar cognitive processes and brain regions. On one hand, both map potentially ambiguous stimuli to a smaller set of motor responses. On the other hand, decisions about perceptual salience typically concern concrete sensory representations derived from a noisy stimulus, while categorization is typically conceptualized as an abstract decision about membership in a potentially arbitrary set. Previous work has primarily examined these types of decisions in isolation. Here we independently varied salience in both the perceptual and categorical domains in a random dot-motion framework by manipulating dot-motion coherence and motion direction relative to a category boundary, respectively. Behavioral and modeling results suggest that categorical (more abstract) information, which is more relevant to subjects' decisions, is weighted more strongly than perceptual (more concrete) information, although they also have significant interactive effects on choice. Within the brain, BOLD activity within frontal regions strongly differentiated categorical salience and weakly differentiated perceptual salience; however, the interaction between these two factors activated similar frontoparietal brain networks. Notably, explicitly evaluating feature interactions revealed a frontal-parietal dissociation: parietal activity varied strongly with both features, but frontal activity varied with the combined strength of the information that defined the motor response. Together, these data demonstrate that frontal regions are driven by decision-relevant features and argue that perceptual decisions and rule-based categorization reflect similar cognitive processes and activate similar brain networks to the extent that they define decision-relevant stimulus-response mappings. NEW & NOTEWORTHY Here we study the behavioral and neural dynamics of perceptual categorization when decision information varies in multiple domains at different levels of abstraction. Behavioral and modeling results suggest that categorical (more abstract) information is weighted more strongly than perceptual (more concrete) information but that perceptual and categorical domains interact to influence decisions. Frontoparietal brain activity during categorization flexibly represents decision-relevant features and highlights significant dissociations in frontal and parietal activity during decision making. Copyright © 2017 the American Physiological Society.

Perceptual and categorical decision making: goal-relevant representation of two domains at different levels of abstraction

PubMed Central

Kayser, Andrew S.

2017-01-01

To date it has been unclear whether perceptual decision making and rule-based categorization reflect activation of similar cognitive processes and brain regions. On one hand, both map potentially ambiguous stimuli to a smaller set of motor responses. On the other hand, decisions about perceptual salience typically concern concrete sensory representations derived from a noisy stimulus, while categorization is typically conceptualized as an abstract decision about membership in a potentially arbitrary set. Previous work has primarily examined these types of decisions in isolation. Here we independently varied salience in both the perceptual and categorical domains in a random dot-motion framework by manipulating dot-motion coherence and motion direction relative to a category boundary, respectively. Behavioral and modeling results suggest that categorical (more abstract) information, which is more relevant to subjects’ decisions, is weighted more strongly than perceptual (more concrete) information, although they also have significant interactive effects on choice. Within the brain, BOLD activity within frontal regions strongly differentiated categorical salience and weakly differentiated perceptual salience; however, the interaction between these two factors activated similar frontoparietal brain networks. Notably, explicitly evaluating feature interactions revealed a frontal-parietal dissociation: parietal activity varied strongly with both features, but frontal activity varied with the combined strength of the information that defined the motor response. Together, these data demonstrate that frontal regions are driven by decision-relevant features and argue that perceptual decisions and rule-based categorization reflect similar cognitive processes and activate similar brain networks to the extent that they define decision-relevant stimulus-response mappings. NEW & NOTEWORTHY Here we study the behavioral and neural dynamics of perceptual categorization when decision information varies in multiple domains at different levels of abstraction. Behavioral and modeling results suggest that categorical (more abstract) information is weighted more strongly than perceptual (more concrete) information but that perceptual and categorical domains interact to influence decisions. Frontoparietal brain activity during categorization flexibly represents decision-relevant features and highlights significant dissociations in frontal and parietal activity during decision making. PMID:28250149

WORM - WINDOWED OBSERVATION OF RELATIVE MOTION

NASA Technical Reports Server (NTRS)

Bauer, F.

1994-01-01

The Windowed Observation of Relative Motion, WORM, program is primarily intended for the generation of simple X-Y plots from data created by other programs. It allows the user to label, zoom, and change the scale of various plots. Three dimensional contour and line plots are provided, although with more limited capabilities. The input data can be in binary or ASCII format, although all data must be in the same format. A great deal of control over the details of the plot is provided, such as gridding, size of tick marks, colors, log/semilog capability, time tagging, and multiple and phase plane plots. Many color and monochrome graphics terminals and hard copy printer/plotters are supported. The WORM executive commands, menu selections and macro files can be used to develop plots and tabular data, query the WORM Help library, retrieve data from input files, and invoke VAX DCL commands. WORM generated plots are displayed on local graphics terminals and can be copied using standard hard copy capabilities. Some of the graphics features of WORM include: zooming and dezooming various portions of the plot; plot documentation including curve labeling and function listing; multiple curves on the same plot; windowing of multiple plots and insets of the same plot; displaying a specific on a curve; and spinning the curve left, right, up, and down. WORM is written in PASCAL for interactive execution and has been implemented on a DEC VAX computer operating under VMS 4.7 with a virtual memory requirement of approximately 392K of 8 bit bytes. It uses the QPLOT device independent graphics library included with WORM. It was developed in 1988.

Changes in Upper Extremity Range of Motion and Efficiency in Multiple Sclerosis Patients Due to Water Activity.

ERIC Educational Resources Information Center

Duthie, Pamela Rae

To determine the effects of water exercise on the movements of multiple sclerosis patients, this study utilized tests to determine changes in the linear range of motion of the shoulder, elbow, and wrist after a 45-minute period of water activities and to determine if the movement became more effective. The test used was an overhead throw with a…

Inhomogeneity of PAGs in resist film studied by molecular-dynamics simulations for EUV lithography

NASA Astrophysics Data System (ADS)

Toriumi, Minoru; Itani, Toshiro

2014-03-01

EUV resist materials are requested simultaneously to improve the resolution, line-edge roughness (LER), and sensitivity (RLS). In a resist film inhomogeneous structures in nanometer region may have large effects on directly the resolution and LER and indirectly on sensitivity. Inhomogeneity of PAGs in a hybrid resist for EUV lithography was investigated using molecular dynamics simulations. The hybrid resist film showed the inhomogeneous positions and motions of PAG cations and anions. Free volumes in resist matrix influence the motions of PAGs. Molecular structure such as bulky phenyl groups of a PAG cation localize the positions and reduce the motion of a cation. Chemical properties such as ionic interactions and lone-pair interaction also play an important role to determine the inhomogeneity of PAGs. Fluorine interaction enables active motions of PAG anions.

Coupling of Lever Arm Swing and Biased Brownian Motion in Actomyosin

PubMed Central

Nie, Qing-Miao; Togashi, Akio; Sasaki, Takeshi N.; Takano, Mitsunori; Sasai, Masaki; Terada, Tomoki P.

2014-01-01

An important unresolved problem associated with actomyosin motors is the role of Brownian motion in the process of force generation. On the basis of structural observations of myosins and actins, the widely held lever-arm hypothesis has been proposed, in which proteins are assumed to show sequential structural changes among observed and hypothesized structures to exert mechanical force. An alternative hypothesis, the Brownian motion hypothesis, has been supported by single-molecule experiments and emphasizes more on the roles of fluctuating protein movement. In this study, we address the long-standing controversy between the lever-arm hypothesis and the Brownian motion hypothesis through in silico observations of an actomyosin system. We study a system composed of myosin II and actin filament by calculating free-energy landscapes of actin-myosin interactions using the molecular dynamics method and by simulating transitions among dynamically changing free-energy landscapes using the Monte Carlo method. The results obtained by this combined multi-scale calculation show that myosin with inorganic phosphate (Pi) and ADP weakly binds to actin and that after releasing Pi and ADP, myosin moves along the actin filament toward the strong-binding site by exhibiting the biased Brownian motion, a behavior consistent with the observed single-molecular behavior of myosin. Conformational flexibility of loops at the actin-interface of myosin and the N-terminus of actin subunit is necessary for the distinct bias in the Brownian motion. Both the 5.5–11 nm displacement due to the biased Brownian motion and the 3–5 nm displacement due to lever-arm swing contribute to the net displacement of myosin. The calculated results further suggest that the recovery stroke of the lever arm plays an important role in enhancing the displacement of myosin through multiple cycles of ATP hydrolysis, suggesting a unified movement mechanism for various members of the myosin family. PMID:24762409

Coupling of lever arm swing and biased Brownian motion in actomyosin.

PubMed

Nie, Qing-Miao; Togashi, Akio; Sasaki, Takeshi N; Takano, Mitsunori; Sasai, Masaki; Terada, Tomoki P

2014-04-01

An important unresolved problem associated with actomyosin motors is the role of Brownian motion in the process of force generation. On the basis of structural observations of myosins and actins, the widely held lever-arm hypothesis has been proposed, in which proteins are assumed to show sequential structural changes among observed and hypothesized structures to exert mechanical force. An alternative hypothesis, the Brownian motion hypothesis, has been supported by single-molecule experiments and emphasizes more on the roles of fluctuating protein movement. In this study, we address the long-standing controversy between the lever-arm hypothesis and the Brownian motion hypothesis through in silico observations of an actomyosin system. We study a system composed of myosin II and actin filament by calculating free-energy landscapes of actin-myosin interactions using the molecular dynamics method and by simulating transitions among dynamically changing free-energy landscapes using the Monte Carlo method. The results obtained by this combined multi-scale calculation show that myosin with inorganic phosphate (Pi) and ADP weakly binds to actin and that after releasing Pi and ADP, myosin moves along the actin filament toward the strong-binding site by exhibiting the biased Brownian motion, a behavior consistent with the observed single-molecular behavior of myosin. Conformational flexibility of loops at the actin-interface of myosin and the N-terminus of actin subunit is necessary for the distinct bias in the Brownian motion. Both the 5.5-11 nm displacement due to the biased Brownian motion and the 3-5 nm displacement due to lever-arm swing contribute to the net displacement of myosin. The calculated results further suggest that the recovery stroke of the lever arm plays an important role in enhancing the displacement of myosin through multiple cycles of ATP hydrolysis, suggesting a unified movement mechanism for various members of the myosin family.

Project Physics Tests 2, Motion in the Heavens.

ERIC Educational Resources Information Center

Harvard Univ., Cambridge, MA. Harvard Project Physics.

Test items relating to Project Physics Unit 2 are presented in this booklet. Included are 70 multiple-choice and 22 problem-and-essay questions. Concepts of motion in the heavens are examined for planetary motions, heliocentric theory, forces exerted on the planets, Kepler's laws, gravitational force, Galileo's work, satellite orbits, Jupiter's…

NMR dipolar constants of motion in liquid crystals: Jeener-Broekaert, double quantum coherence experiments and numerical calculation on a 10-spin cluster.

PubMed

Segnorile, H H; Bonin, C J; González, C E; Acosta, R H; Zamar, R C

2009-10-01

Two proton quasi-equilibrium states were previously observed in nematic liquid crystals, namely the S and W quasi-invariants. Even though the experimental evidence suggested that they originate in a partition of the spin dipolar energy into a strong and a weak part, respectively, from a theoretical viewpoint, the existence of an appropriate energy scale which allows such energy separation remains to be confirmed and a representation of the quasi-invariants is still to be given. We compare the dipolar NMR signals yielded both by the Jeener-Broekaert (JB) experiment as a function of the preparation time and the free evolution of the double quantum coherence (DQC) spectra excited from the S state, with numerical calculations carried out from first principles under different models for the dipolar quasi-invariants, in a 10-spin cluster which represents the 5CB (4(')-pentyl-4-biphenyl-carbonitrile) molecule. The calculated signals qualitatively agree with the experiments and the DQC spectra as a function of the single-quantum detection time are sensible enough to the different models to allow both to probe the physical nature of the initial dipolar-ordered state and to assign a subset of dipolar interactions to each constant of motion, which are compatible with the experiments. As a criterion for selecting a suitable quasi-equilibrium model of the 5CB molecule, we impose on the time evolution operator consistency with the occurrence of two dipolar quasi-invariants, that is, the calculated spectra must be unaffected by truncation of non-secular terms of the weaker dipolar energy. We find that defining the S quasi-invariant as the subset of the dipolar interactions of each proton with its two nearest neighbours yields a realistic characterization of the dipolar constants of motion in 5CB. We conclude that the proton-spin system of the 5CB molecule admits a partition of the dipolar energy into a bilinear strong and a multiple-spin weak contributions therefore providing two orthogonal constants of motion, which can be prepared and observed by means of the JB experiment. This feature, which implies the existence of two timescales of very different nature in the proton-spin dynamics, is ultimately dictated by the topology of the spin distribution in the dipole network and can be expected in other liquid crystals. Knowledge of the nature of the dipolar quasi-invariants will be useful in studies of dipolar-order relaxation, decoherence and multiple quantum NMR experiments where the initial state is a dipolar-ordered one.

Subject-Specific Carpal Ligament Elongation in Extreme Positions, Grip, and the Dart Thrower's Motion

PubMed Central

Rainbow, Michael J.; Kamal, Robin N.; Moore, Douglas C.; Akelman, Edward; Wolfe, Scott W.; Crisco, Joseph J.

2015-01-01

This study examined whether the radiocarpal and dorsal capsular ligaments limit end-range wrist motion or remain strained during midrange wrist motion. Fibers of these ligaments were modeled in the wrists of 12 subjects over multiple wrist positions that reflect high demand tasks and the dart thrower's motion. We found that many of the volar and dorsal ligaments were within 5% of their maximum length throughout the range of wrist motion. Our finding of wrist ligament recruitment during midrange and end-range wrist motion helps to explain the complex but remarkably similar intersubject patterns of carpal motion. PMID:26367853

Effective seat-to-head transmissibility in whole-body vibration: Effects of posture and arm position

NASA Astrophysics Data System (ADS)

Rahmatalla, Salam; DeShaw, Jonathan

2011-12-01

Seat-to-head transmissibility is a biomechanical measure that has been widely used for many decades to evaluate seat dynamics and human response to vibration. Traditionally, transmissibility has been used to correlate single-input or multiple-input with single-output motion; it has not been effectively used for multiple-input and multiple-output scenarios due to the complexity of dealing with the coupled motions caused by the cross-axis effect. This work presents a novel approach to use transmissibility effectively for single- and multiple-input and multiple-output whole-body vibrations. In this regard, the full transmissibility matrix is transformed into a single graph, such as those for single-input and single-output motions. Singular value decomposition and maximum distortion energy theory were used to achieve the latter goal. Seat-to-head transmissibility matrices for single-input/multiple-output in the fore-aft direction, single-input/multiple-output in the vertical direction, and multiple-input/multiple-output directions are investigated in this work. A total of ten subjects participated in this study. Discrete frequencies of 0.5-16 Hz were used for the fore-aft direction using supported and unsupported back postures. Random ride files from a dozer machine were used for the vertical and multiple-axis scenarios considering two arm postures: using the armrests or grasping the steering wheel. For single-input/multiple-output, the results showed that the proposed method was very effective in showing the frequencies where the transmissibility is mostly sensitive for the two sitting postures and two arm positions. For multiple-input/multiple-output, the results showed that the proposed effective transmissibility indicated higher values for the armrest-supported posture than for the steering-wheel-supported posture.

Direction selectivity of blowfly motion-sensitive neurons is computed in a two-stage process.

PubMed Central

Borst, A; Egelhaaf, M

1990-01-01

Direction selectivity of motion-sensitive neurons is generally thought to result from the nonlinear interaction between the signals derived from adjacent image points. Modeling of motion-sensitive networks, however, reveals that such elements may still respond to motion in a rather poor directionally selective way. Direction selectivity can be significantly enhanced if the nonlinear interaction is followed by another processing stage in which the signals of elements with opposite preferred directions are subtracted from each other. Our electrophysiological experiments in the fly visual system suggest that here direction selectivity is acquired in such a two-stage process. Images PMID:2251278

Design principles of a cooperative robot controller

NASA Technical Reports Server (NTRS)

Hayward, Vincent; Hayati, Samad

1987-01-01

The paper describes the design of a controller for cooperative robots being designed at McGill University in a collaborative effort with the Jet Propulsion Laboratory. The first part of the paper discusses the background and motivation for multiple arm control. Then, a set of programming primitives, which are based on the RCCL system and which permit a programmer to specify cooperative tasks are described. The first group of primitives are motion primitives which specify asynchronous motions, master/slave motions, and cooperative motions. In the context of cooperative robots, trajectory generation issues will be discussed and the implementation described. A second set of primitives provides for the specification of spatial relationships. The relations between programming and control in the case of multiple robot are examined. Finally, the paper describes the allocation of various tasks among a set of microprocessors sharing a common bus.

Reliability of psychophysiological responses across multiple motion sickness stimulation tests

NASA Technical Reports Server (NTRS)

Stout, C. S.; Toscano, W. B.; Cowings, P. S.

1995-01-01

Although there is general agreement that a high degree of variability exists between subjects in their autonomic nervous system responses to motion sickness stimulation, very little evidence exists that examines the reproducibility of autonomic responses within subjects during motion sickness stimulation. Our objectives were to examine the reliability of autonomic responses and symptom levels across five testing occasions using the (1) final minute of testing, (2) change in autonomic response and the change in symptom level, and (3) strength of the relationship between the change in symptom level and the change in autonomic responses across the entire motion sickness test. The results indicate that, based on the final minute of testing, the autonomic responses of heart rate, blood volume pulse, and respiration rate are moderately stable across multiple tests. Changes in heart rate, blood volume pulse, respiration rate, and symptoms throughout the test duration are less stable across the tests. Finally, autonomic responses and symptom levels are significantly related across the entire motion sickness test.

Spatial Attention and Audiovisual Interactions in Apparent Motion

ERIC Educational Resources Information Center

Sanabria, Daniel; Soto-Faraco, Salvador; Spence, Charles

2007-01-01

In this study, the authors combined the cross-modal dynamic capture task (involving the horizontal apparent movement of visual and auditory stimuli) with spatial cuing in the vertical dimension to investigate the role of spatial attention in cross-modal interactions during motion perception. Spatial attention was manipulated endogenously, either…

CD-I and Full Motion Video.

ERIC Educational Resources Information Center

Chen, Ching-chih

1991-01-01

Describes compact disc interactive (CD-I) as a multimedia home entertainment system that combines audio, visual, text, graphic, and interactive capabilities. Full-screen video and full-motion video (FMV) are explained, hardware for FMV decoding is described, software is briefly discussed, and CD-I titles planned for future production are listed.…

MOCAD: A Tool for Graphical and Interactive Calculation and Optimization of Cam Mechanisms and Motion Control Systems

NASA Astrophysics Data System (ADS)

Heine, A.; Berger, M.

The classical meaning of motion design is the usage of laws of motion with convenient characteristic values. Whereas the software MOCAD supports a graphical and interactive mode of operation, among others by using an automatic polynomial interpolation. Besides a direct coupling for motion control systems, different file formats for data export are offered. The calculation of plane and spatial cam mechanisms is also based on the data, generated in the motion design module. Drawing on an example of an intermittent cam mechanism with an inside cam profile used as a new drive concept for indexing tables, the influence of motion design on the transmission properties is shown. Another example gives an insight into the calculation and export of envelope curves for cylindrical cam mechanisms. The gained geometry data can be used for generating realistic 3D-models in the CAD-system Pro/ENGINEER, using a special data exchange format.

Smelling directions: Olfaction modulates ambiguous visual motion perception

PubMed Central

Kuang, Shenbing; Zhang, Tao

2014-01-01

Senses of smells are often accompanied by simultaneous visual sensations. Previous studies have documented enhanced olfactory performance with concurrent presence of congruent color- or shape- related visual cues, and facilitated visual object perception when congruent smells are simultaneously present. These visual object-olfaction interactions suggest the existences of couplings between the olfactory pathway and the visual ventral processing stream. However, it is not known if olfaction can modulate visual motion perception, a function that is related to the visual dorsal stream. We tested this possibility by examining the influence of olfactory cues on the perceptions of ambiguous visual motion signals. We showed that, after introducing an association between motion directions and olfactory cues, olfaction could indeed bias ambiguous visual motion perceptions. Our result that olfaction modulates visual motion processing adds to the current knowledge of cross-modal interactions and implies a possible functional linkage between the olfactory system and the visual dorsal pathway. PMID:25052162

An artificial muscle actuator for biomimetic underwater propulsors.

PubMed

Yim, Woosoon; Lee, Joonsoo; Kim, Kwang J

2007-06-01

In this paper, we introduce the analytical framework of the modeling dynamic characteristics of a soft artificial muscle actuator for aquatic propulsor applications. The artificial muscle used for this underwater application is an ionic polymer-metal composite (IPMC) which can generate bending motion in aquatic environments. The inputs of the model are the voltages applied to multiple IPMCs, and the output can be either the shape of the actuators or the thrust force generated from the interaction between dynamic actuator motions and surrounding water. In order to determine the relationship between the input voltages and the bending moments, the simplified RC model is used, and the mechanical beam theory is used for the bending motion of IPMC actuators. Also, the hydrodynamic forces exerted on an actuator as it moves relative to the surrounding medium or water are added to the equations of motion to study the effect of actuator bending on the thrust force generation. The proposed method can be used for modeling the general bending type artificial muscle actuator in a single or segmented form operating in the water. The segmented design has more flexibility in controlling the shape of the actuator when compared with the single form, especially in generating undulatory waves. Considering an inherent nature of large deformations in the IPMC actuator, a large deflection beam model has been developed and integrated with the electrical RC model and hydrodynamic forces to develop the state space model of the actuator system. The model was validated against existing experimental data.

A Methodology for Evaluating the Hygroscopic Behavior of Wood in Adaptive Building Skins using Motion Grammar

NASA Astrophysics Data System (ADS)

El-Dabaa, Rana; Abdelmohsen, Sherif

2018-05-01

The challenge in designing kinetic architecture lies in the lack of applying computational design and human computer interaction to successfully design intelligent and interactive interfaces. The use of ‘programmable materials’ as specifically fabricated composite materials that afford motion upon stimulation is promising for low-cost low-tech systems for kinetic facades in buildings. Despite efforts to develop working prototypes, there has been no clear methodological framework for understanding and controlling the behavior of programmable materials or for using them for such purposes. This paper introduces a methodology for evaluating the motion acquired from programmed material – resulting from the hygroscopic behavior of wood – through ‘motion grammar’. Motion grammar typically allows for the explanation of desired motion control in a computationally tractable method. The paper analyzed and evaluated motion parameters related to the hygroscopic properties and behavior of wood, and introduce a framework for tracking and controlling wood as a programmable material for kinetic architecture.

Dynamical evolution of motion perception.

PubMed

Kanai, Ryota; Sheth, Bhavin R; Shimojo, Shinsuke

2007-03-01

Motion is defined as a sequence of positional changes over time. However, in perception, spatial position and motion dynamically interact with each other. This reciprocal interaction suggests that the perception of a moving object itself may dynamically evolve following the onset of motion. Here, we show evidence that the percept of a moving object systematically changes over time. In experiments, we introduced a transient gap in the motion sequence or a brief change in some feature (e.g., color or shape) of an otherwise smoothly moving target stimulus. Observers were highly sensitive to the gap or transient change if it occurred soon after motion onset (< or =200 ms), but significantly less so if it occurred later (> or = 300 ms). Our findings suggest that the moving stimulus is initially perceived as a time series of discrete potentially isolatable frames; later failures to perceive change suggests that over time, the stimulus begins to be perceived as a single, indivisible gestalt integrated over space as well as time, which could well be the signature of an emergent stable motion percept.

Recording High Resolution 3D Lagrangian Motions In Marine Dinoflagellates using Digital Holographic Microscopic Cinematography

NASA Astrophysics Data System (ADS)

Sheng, J.; Malkiel, E.; Katz, J.; Place, A. R.; Belas, R.

2006-11-01

Detailed data on swimming behavior and locomotion for dense population of dinoflagellates constitutes a key component to understanding cell migration, cell-cell interactions and predator-prey dynamics, all of which affect algae bloom dynamics. Due to the multi-dimensional nature of flagellated cell motions, spatial-temporal Lagrangian measurements of multiple cells in high concentration are very limited. Here we present detailed data on 3D Lagrangian motions for three marine dinoflagellates: Oxyrrhis marina, Karlodinium veneficum, and Pfiesteria piscicida, using digital holographic microscopic cinematography. The measurements are performed in a 5x5x25mm cuvette with cell densities varying from 50,000 ˜ 90,000 cells/ml. Approximately 200-500 cells are tracked simultaneously for 12s at 60fps in a sample volume of 1x1x5 mm at a spatial resolution of 0.4x0.4x2 μm. We fully resolve the longitudinal flagella (˜200nm) along with the Lagrangian trajectory of each organism. Species dependent swimming behavior are identified and categorized quantitatively by velocities, radii of curvature, and rotations of pitch. Statistics on locomotion, temporal & spatial scales, and diffusion rate show substantial differences between species. The scaling between turning radius and cell dimension can be explained by a distributed stokeslet model for a self-propelled body.

Motion capture for human motion measuring by using single camera with triangle markers

NASA Astrophysics Data System (ADS)

Takahashi, Hidenori; Tanaka, Takayuki; Kaneko, Shun'ichi

2005-12-01

This study aims to realize a motion capture for measuring 3D human motions by using single camera. Although motion capture by using multiple cameras is widely used in sports field, medical field, engineering field and so on, optical motion capture method with one camera is not established. In this paper, the authors achieved a 3D motion capture by using one camera, named as Mono-MoCap (MMC), on the basis of two calibration methods and triangle markers which each length of side is given. The camera calibration methods made 3D coordinates transformation parameter and a lens distortion parameter with Modified DLT method. The triangle markers enabled to calculate a coordinate value of a depth direction on a camera coordinate. Experiments of 3D position measurement by using the MMC on a measurement space of cubic 2 m on each side show an average error of measurement of a center of gravity of a triangle marker was less than 2 mm. As compared with conventional motion capture method by using multiple cameras, the MMC has enough accuracy for 3D measurement. Also, by putting a triangle marker on each human joint, the MMC was able to capture a walking motion, a standing-up motion and a bending and stretching motion. In addition, a method using a triangle marker together with conventional spherical markers was proposed. Finally, a method to estimate a position of a marker by measuring the velocity of the marker was proposed in order to improve the accuracy of MMC.

Suggested Courseware for the Non-Calculus Physics Student: Simple Harmonic Motion, Wave Motion, and Sound.

ERIC Educational Resources Information Center

Grable-Wallace, Lisa; And Others

1989-01-01

Evaluates 5 courseware packages covering the topics of simple harmonic motion, 7 packages for wave motion, and 10 packages for sound. Discusses the price range, sub-topics, program type, interaction, time, calculus required, graphics, and comments of each courseware. Selects several packages based on the criteria. (YP)

Use of natural user interfaces in water simulations

NASA Astrophysics Data System (ADS)

Donchyts, G.; Baart, F.; van Dam, A.; Jagers, B.

2013-12-01

Conventional graphical user interfaces, used to edit input and present results of earth science models, have seen little innovation for the past two decades. In most cases model data is presented and edited using 2D projections even when working with 3D data. The emergence of 3D motion sensing technologies, such as Microsoft Kinect and LEAP Motion, opens new possibilities for user interaction by adding more degrees of freedom compared to a classical way using mouse and keyboard. Here we investigate how interaction with hydrodynamic numerical models can be improved using these new technologies. Our research hypothesis (H1) states that properly designed 3D graphical user interface paired with the 3D motion sensor can significantly reduce the time required to setup and use numerical models. In this work we have used a LEAP motion controller combined with a shallow water flow model engine D-Flow Flexible Mesh. Interacting with numerical model using hands

Mapping multivalency and differential affinities within large intrinsically disordered protein complexes with segmental motion analysis.

PubMed

Milles, Sigrid; Lemke, Edward A

2014-07-07

Intrinsically disordered proteins (IDPs) can bind to multiple interaction partners. Numerous binding regions in the IDP that act in concert through complex cooperative effects facilitate such interactions, but complicate studying IDP complexes. To address this challenge we developed a combined fluorescence correlation and time-resolved polarization spectroscopy approach to study the binding properties of the IDP nucleoporin153 (Nup153) to nuclear transport receptors (NTRs). The detection of segmental backbone mobility of Nup153 within the unperturbed complex provided a readout of local, region-specific binding properties that are usually masked in measurements of the whole IDP. The binding affinities of functionally and structurally diverse NTRs to distinct regions of Nup153 can differ by orders of magnitudes-a result with implications for the diversity of transport routes in nucleocytoplasmic transport. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Mean Field Limits for Interacting Diffusions in a Two-Scale Potential

NASA Astrophysics Data System (ADS)

Gomes, S. N.; Pavliotis, G. A.

2018-06-01

In this paper, we study the combined mean field and homogenization limits for a system of weakly interacting diffusions moving in a two-scale, locally periodic confining potential, of the form considered in Duncan et al. (Brownian motion in an N-scale periodic potential, arXiv:1605.05854, 2016b). We show that, although the mean field and homogenization limits commute for finite times, they do not, in general, commute in the long time limit. In particular, the bifurcation diagrams for the stationary states can be different depending on the order with which we take the two limits. Furthermore, we construct the bifurcation diagram for the stationary McKean-Vlasov equation in a two-scale potential, before passing to the homogenization limit, and we analyze the effect of the multiple local minima in the confining potential on the number and the stability of stationary solutions.

One-Dimensional Brownian Motion of Charged Nanoparticles along Microtubules: A Model System for Weak Binding Interactions

PubMed Central

Minoura, Itsushi; Katayama, Eisaku; Sekimoto, Ken; Muto, Etsuko

2010-01-01

Abstract Various proteins are known to exhibit one-dimensional Brownian motion along charged rodlike polymers, such as microtubules (MTs), actin, and DNA. The electrostatic interaction between the proteins and the rodlike polymers appears to be crucial for one-dimensional Brownian motion, although the underlying mechanism has not been fully clarified. We examined the interactions of positively-charged nanoparticles composed of polyacrylamide gels with MTs. These hydrophilic nanoparticles bound to MTs and displayed one-dimensional Brownian motion in a charge-dependent manner, which indicates that nonspecific electrostatic interaction is sufficient for one-dimensional Brownian motion. The diffusion coefficient decreased exponentially with an increasing particle charge (with the exponent being 0.10 kBT per charge), whereas the duration of the interaction increased exponentially (exponent of 0.22 kBT per charge). These results can be explained semiquantitatively if one assumes that a particle repeats a cycle of binding to and movement along an MT until it finally dissociates from the MT. During the movement, a particle is still electrostatically constrained in the potential valley surrounding the MT. This entire process can be described by a three-state model analogous to the Michaelis-Menten scheme, in which the two parameters of the equilibrium constant between binding and movement, and the rate of dissociation from the MT, are derived as a function of the particle charge density. This study highlights the possibility that the weak binding interactions between proteins and rodlike polymers, e.g., MTs, are mediated by a similar, nonspecific charge-dependent mechanism. PMID:20409479

One-dimensional Brownian motion of charged nanoparticles along microtubules: a model system for weak binding interactions.

PubMed

Minoura, Itsushi; Katayama, Eisaku; Sekimoto, Ken; Muto, Etsuko

2010-04-21

Various proteins are known to exhibit one-dimensional Brownian motion along charged rodlike polymers, such as microtubules (MTs), actin, and DNA. The electrostatic interaction between the proteins and the rodlike polymers appears to be crucial for one-dimensional Brownian motion, although the underlying mechanism has not been fully clarified. We examined the interactions of positively-charged nanoparticles composed of polyacrylamide gels with MTs. These hydrophilic nanoparticles bound to MTs and displayed one-dimensional Brownian motion in a charge-dependent manner, which indicates that nonspecific electrostatic interaction is sufficient for one-dimensional Brownian motion. The diffusion coefficient decreased exponentially with an increasing particle charge (with the exponent being 0.10 kBT per charge), whereas the duration of the interaction increased exponentially (exponent of 0.22 kBT per charge). These results can be explained semiquantitatively if one assumes that a particle repeats a cycle of binding to and movement along an MT until it finally dissociates from the MT. During the movement, a particle is still electrostatically constrained in the potential valley surrounding the MT. This entire process can be described by a three-state model analogous to the Michaelis-Menten scheme, in which the two parameters of the equilibrium constant between binding and movement, and the rate of dissociation from the MT, are derived as a function of the particle charge density. This study highlights the possibility that the weak binding interactions between proteins and rodlike polymers, e.g., MTs, are mediated by a similar, nonspecific charge-dependent mechanism. Copyright 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Interaction force and motion estimators facilitating impedance control of the upper limb rehabilitation robot.

PubMed

Mancisidor, Aitziber; Zubizarreta, Asier; Cabanes, Itziar; Bengoa, Pablo; Jung, Je Hyung

2017-07-01

In order to enhance the performance of rehabilitation robots, it is imperative to know both force and motion caused by the interaction between user and robot. However, common direct measurement of both signals through force and motion sensors not only increases the complexity of the system but also impedes affordability of the system. As an alternative of the direct measurement, in this work, we present new force and motion estimators for the proper control of the upper-limb rehabilitation Universal Haptic Pantograph (UHP) robot. The estimators are based on the kinematic and dynamic model of the UHP and the use of signals measured by means of common low-cost sensors. In order to demonstrate the effectiveness of the estimators, several experimental tests were carried out. The force and impedance control of the UHP was implemented first by directly measuring the interaction force using accurate extra sensors and the robot performance was compared to the case where the proposed estimators replace the direct measured values. The experimental results reveal that the controller based on the estimators has similar performance to that using direct measurement (less than 1 N difference in root mean square error between two cases), indicating that the proposed force and motion estimators can facilitate implementation of interactive controller for the UHP in robotmediated rehabilitation trainings.

Inquiry style interactive virtual experiments: a case on circular motion

NASA Astrophysics Data System (ADS)

Zhou, Shaona; Han, Jing; Pelz, Nathaniel; Wang, Xiaojun; Peng, Liangyu; Xiao, Hua; Bao, Lei

2011-11-01

Interest in computer-based learning, especially in the use of virtual reality simulations is increasing rapidly. While there are good reasons to believe that technologies have the potential to improve teaching and learning, how to utilize the technology effectively in teaching specific content difficulties is challenging. To help students develop robust understandings of correct physics concepts, we have developed interactive virtual experiment simulations that have the unique feature of enabling students to experience force and motion via an analogue joystick, allowing them to feel the applied force and simultaneously see its effects. The simulations provide students learning experiences that integrate both scientific representations and low-level sensory cues such as haptic cues under a single setting. In this paper, we introduce a virtual experiment module on circular motion. A controlled study has been conducted to evaluate the impact of using this virtual experiment on students' learning of force and motion in the context of circular motion. The results show that the interactive virtual experiment method is preferred by students and is more effective in helping students grasp the physics concepts than the traditional education method such as problem-solving practices. Our research suggests that well-developed interactive virtual experiments can be useful tools in teaching difficult concepts in science.

Correlation between hip function and knee kinematics evaluated by three-dimensional motion analysis during lateral and medial side-hopping.

PubMed

Itoh, Hiromitsu; Takiguchi, Kohei; Shibata, Yohei; Okubo, Satoshi; Yoshiya, Shinichi; Kuroda, Ryosuke

2016-09-01

[Purpose] Kinematic and kinetic characteristics of the limb during side-hopping and hip/knee interaction during this motion have not been clarified. The purposes of this study were to examine the biomechanical parameters of the knee during side hop and analyze its relationship with clinical measurements of hip function. [Subjects and Methods] Eleven male college rugby players were included. A three-dimensional motion analysis system was used to assess motion characteristics of the knee during side hop. In addition, hip range of motion and muscle strength were evaluated. Subsequently, the relationship between knee motion and the clinical parameters of the hip was analyzed. [Results] In the lateral touchdown phase, the knee was positioned in an abducted and externally rotated position, and increasing abduction moment was applied to the knee. An analysis of the interaction between knee motion and hip function showed that range of motion for hip internal rotation was significantly correlated with external rotation angle and external rotation/abduction moments of the knee during the lateral touchdown phase. [Conclusion] Range of motion for hip internal rotation should be taken into consideration for identifying the biomechanical characteristics in the side hop test results.

Correlation between hip function and knee kinematics evaluated by three-dimensional motion analysis during lateral and medial side-hopping

PubMed Central

Itoh, Hiromitsu; Takiguchi, Kohei; Shibata, Yohei; Okubo, Satoshi; Yoshiya, Shinichi; Kuroda, Ryosuke

2016-01-01

[Purpose] Kinematic and kinetic characteristics of the limb during side-hopping and hip/knee interaction during this motion have not been clarified. The purposes of this study were to examine the biomechanical parameters of the knee during side hop and analyze its relationship with clinical measurements of hip function. [Subjects and Methods] Eleven male college rugby players were included. A three-dimensional motion analysis system was used to assess motion characteristics of the knee during side hop. In addition, hip range of motion and muscle strength were evaluated. Subsequently, the relationship between knee motion and the clinical parameters of the hip was analyzed. [Results] In the lateral touchdown phase, the knee was positioned in an abducted and externally rotated position, and increasing abduction moment was applied to the knee. An analysis of the interaction between knee motion and hip function showed that range of motion for hip internal rotation was significantly correlated with external rotation angle and external rotation/abduction moments of the knee during the lateral touchdown phase. [Conclusion] Range of motion for hip internal rotation should be taken into consideration for identifying the biomechanical characteristics in the side hop test results. PMID:27799670

Tracking multiple particles in fluorescence time-lapse microscopy images via probabilistic data association.

PubMed

Godinez, William J; Rohr, Karl

2015-02-01

Tracking subcellular structures as well as viral structures displayed as 'particles' in fluorescence microscopy images yields quantitative information on the underlying dynamical processes. We have developed an approach for tracking multiple fluorescent particles based on probabilistic data association. The approach combines a localization scheme that uses a bottom-up strategy based on the spot-enhancing filter as well as a top-down strategy based on an ellipsoidal sampling scheme that uses the Gaussian probability distributions computed by a Kalman filter. The localization scheme yields multiple measurements that are incorporated into the Kalman filter via a combined innovation, where the association probabilities are interpreted as weights calculated using an image likelihood. To track objects in close proximity, we compute the support of each image position relative to the neighboring objects of a tracked object and use this support to recalculate the weights. To cope with multiple motion models, we integrated the interacting multiple model algorithm. The approach has been successfully applied to synthetic 2-D and 3-D images as well as to real 2-D and 3-D microscopy images, and the performance has been quantified. In addition, the approach was successfully applied to the 2-D and 3-D image data of the recent Particle Tracking Challenge at the IEEE International Symposium on Biomedical Imaging (ISBI) 2012.

Analysis of cardiac interventricular septum motion in different respiratory states

NASA Astrophysics Data System (ADS)

Tautz, Lennart; Feng, Li; Otazo, Ricardo; Hennemuth, Anja; Axel, Leon

2016-03-01

The interaction between the left and right heart ventricles (LV and RV) depends on load and pressure conditions that are affected by cardiac contraction and respiration cycles. A novel MRI sequence, XD-GRASP, allows the acquisition of multi-dimensional, respiration-sorted and cardiac-synchronized free-breathing image data. In these data, effects of the cardiac and respiratory cycles on the LV/RV interaction can be observed independently. To enable the analysis of such data, we developed a semi-automatic exploration workflow. After tracking a cross-sectional line positioned over the heart, over all motion states, the septum and heart wall border locations are detected by analyzing the grey-value profile under the lines. These data are used to quantify septum motion, both in absolute units and as a fraction of the heart size, to compare values for different subjects. In addition to conventional visualization techniques, we used color maps for intuitive exploration of the variable values for this multi-dimensional data set. We acquired short-axis image data of nine healthy volunteers, to analyze the position and the motion of the interventricular septum in different breathing states and different cardiac cycle phases. The results indicate a consistent range of normal septum motion values, and also suggest that respiratory phase-dependent septum motion is greatest near end-diastolic phases. These new methods are a promising tool to assess LV/RV ventricle interaction and the effects of respiration on this interaction.

Brownian microhydrodynamics of active filaments.

PubMed

Laskar, Abhrajit; Adhikari, R

2015-12-21

Slender bodies capable of spontaneous motion in the absence of external actuation in an otherwise quiescent fluid are common in biological, physical and technological contexts. The interplay between the spontaneous fluid flow, Brownian motion, and the elasticity of the body presents a challenging fluid-structure interaction problem. Here, we model this problem by approximating the slender body as an elastic filament that can impose non-equilibrium velocities or stresses at the fluid-structure interface. We derive equations of motion for such an active filament by enforcing momentum conservation in the fluid-structure interaction and assuming slow viscous flow in the fluid. The fluid-structure interaction is obtained, to any desired degree of accuracy, through the solution of an integral equation. A simplified form of the equations of motion, which allows for efficient numerical solutions, is obtained by applying the Kirkwood-Riseman superposition approximation to the integral equation. We use this form of equation of motion to study dynamical steady states in free and hinged minimally active filaments. Our model provides the foundation to study collective phenomena in momentum-conserving, Brownian, active filament suspensions.

Multiple attractors and critical parameters and how to find them numerically: the right, the wrong and the gambling way

NASA Astrophysics Data System (ADS)

True, Hans

2013-03-01

In recent years, several authors have proposed 'easier numerical methods' to find the critical speed in railway dynamical problems. Actually, the methods do function in some cases, but in most cases it is really a gamble. In this article, the methods are discussed and the pros and contras are commented upon. I also address the questions when a linearisation is allowed and the curious fact that the hunting motion is more robust than the ideal stationary-state motion on the track. Concepts such as 'multiple attractors', 'subcritical and supercritical bifurcations', 'permitted linearisation', 'the danger of running at supercritical speeds' and 'chaotic motion' are addressed.

Benchmark Modeling of the Near-Field and Far-Field Wave Effects of Wave Energy Arrays

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

Rhinefrank, Kenneth E; Haller, Merrick C; Ozkan-Haller, H Tuba

2013-01-26

This project is an industry-led partnership between Columbia Power Technologies and Oregon State University that will perform benchmark laboratory experiments and numerical modeling of the near-field and far-field impacts of wave scattering from an array of wave energy devices. These benchmark experimental observations will help to fill a gaping hole in our present knowledge of the near-field effects of multiple, floating wave energy converters and are a critical requirement for estimating the potential far-field environmental effects of wave energy arrays. The experiments will be performed at the Hinsdale Wave Research Laboratory (Oregon State University) and will utilize an array ofmore » newly developed Buoys' that are realistic, lab-scale floating power converters. The array of Buoys will be subjected to realistic, directional wave forcing (1:33 scale) that will approximate the expected conditions (waves and water depths) to be found off the Central Oregon Coast. Experimental observations will include comprehensive in-situ wave and current measurements as well as a suite of novel optical measurements. These new optical capabilities will include imaging of the 3D wave scattering using a binocular stereo camera system, as well as 3D device motion tracking using a newly acquired LED system. These observing systems will capture the 3D motion history of individual Buoys as well as resolve the 3D scattered wave field; thus resolving the constructive and destructive wave interference patterns produced by the array at high resolution. These data combined with the device motion tracking will provide necessary information for array design in order to balance array performance with the mitigation of far-field impacts. As a benchmark data set, these data will be an important resource for testing of models for wave/buoy interactions, buoy performance, and far-field effects on wave and current patterns due to the presence of arrays. Under the proposed project we will initiate high-resolution (fine scale, very near-field) fluid/structure interaction simulations of buoy motions, as well as array-scale, phase-resolving wave scattering simulations. These modeling efforts will utilize state-of-the-art research quality models, which have not yet been brought to bear on this complex problem of large array wave/structure interaction problem.« less

A Situated Cultural Festival Learning System Based on Motion Sensing

ERIC Educational Resources Information Center

Chang, Yi-Hsing; Lin, Yu-Kai; Fang, Rong-Jyue; Lu, You-Te

2017-01-01

A situated Chinese cultural festival learning system based on motion sensing is developed in this study. The primary design principle is to create a highly interactive learning environment, allowing learners to interact with Kinect through natural gestures in the designed learning situation to achieve efficient learning. The system has the…

Hybrid Motion Planning with Multiple Destinations

NASA Technical Reports Server (NTRS)

Clouse, Jeffery

1998-01-01

In our initial proposal, we laid plans for developing a hybrid motion planning system that combines the concepts of visibility-based motion planning, artificial potential field based motion planning, evolutionary constrained optimization, and reinforcement learning. Our goal was, and still is, to produce a hybrid motion planning system that outperforms the best traditional motion planning systems on problems with dynamic environments. The proposed hybrid system will be in two parts the first is a global motion planning system and the second is a local motion planning system. The global system will take global information about the environment, such as the placement of the obstacles and goals, and produce feasible paths through those obstacles. We envision a system that combines the evolutionary-based optimization and visibility-based motion planning to achieve this end.

Lumbar joint torque estimation based on simplified motion measurement using multiple inertial sensors.

PubMed

Miyajima, Saori; Tanaka, Takayuki; Imamura, Yumeko; Kusaka, Takashi

2015-01-01

We estimate lumbar torque based on motion measurement using only three inertial sensors. First, human motion is measured by a 6-axis motion tracking device that combines a 3-axis accelerometer and a 3-axis gyroscope placed on the shank, thigh, and back. Next, the lumbar joint torque during the motion is estimated by kinematic musculoskeletal simulation. The conventional method for estimating joint torque uses full body motion data measured by an optical motion capture system. However, in this research, joint torque is estimated by using only three link angles of the body, thigh, and shank. The utility of our method was verified by experiments. We measured motion of bendung knee and waist simultaneously. As the result, we were able to estimate the lumbar joint torque from measured motion.

Detecting and Analyzing Multiple Moving Objects in Crowded Environments with Coherent Motion Regions

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

Cheriyadat, Anil M.

Understanding the world around us from large-scale video data requires vision systems that can perform automatic interpretation. While human eyes can unconsciously perceive independent objects in crowded scenes and other challenging operating environments, automated systems have difficulty detecting, counting, and understanding their behavior in similar scenes. Computer scientists at ORNL have a developed a technology termed as "Coherent Motion Region Detection" that invloves identifying multiple indepedent moving objects in crowded scenes by aggregating low-level motion cues extracted from moving objects. Humans and other species exploit such low-level motion cues seamlessely to perform perceptual grouping for visual understanding. The algorithm detectsmore » and tracks feature points on moving objects resulting in partial trajectories that span coherent 3D region in the space-time volume defined by the video. In the case of multi-object motion, many possible coherent motion regions can be constructed around the set of trajectories. The unique approach in the algorithm is to identify all possible coherent motion regions, then extract a subset of motion regions based on an innovative measure to automatically locate moving objects in crowded environments.The software reports snapshot of the object, count, and derived statistics ( count over time) from input video streams. The software can directly process videos streamed over the internet or directly from a hardware device (camera).« less

Gain Modulation as a Mechanism for Coding Depth from Motion Parallax in Macaque Area MT

PubMed Central

Kim, HyungGoo R.; Angelaki, Dora E.

2017-01-01

Observer translation produces differential image motion between objects that are located at different distances from the observer's point of fixation [motion parallax (MP)]. However, MP can be ambiguous with respect to depth sign (near vs far), and this ambiguity can be resolved by combining retinal image motion with signals regarding eye movement relative to the scene. We have previously demonstrated that both extra-retinal and visual signals related to smooth eye movements can modulate the responses of neurons in area MT of macaque monkeys, and that these modulations generate neural selectivity for depth sign. However, the neural mechanisms that govern this selectivity have remained unclear. In this study, we analyze responses of MT neurons as a function of both retinal velocity and direction of eye movement, and we show that smooth eye movements modulate MT responses in a systematic, temporally precise, and directionally specific manner to generate depth-sign selectivity. We demonstrate that depth-sign selectivity is primarily generated by multiplicative modulations of the response gain of MT neurons. Through simulations, we further demonstrate that depth can be estimated reasonably well by a linear decoding of a population of MT neurons with response gains that depend on eye velocity. Together, our findings provide the first mechanistic description of how visual cortical neurons signal depth from MP. SIGNIFICANCE STATEMENT Motion parallax is a monocular cue to depth that commonly arises during observer translation. To compute from motion parallax whether an object appears nearer or farther than the point of fixation requires combining retinal image motion with signals related to eye rotation, but the neurobiological mechanisms have remained unclear. This study provides the first mechanistic account of how this interaction takes place in the responses of cortical neurons. Specifically, we show that smooth eye movements modulate the gain of responses of neurons in area MT in a directionally specific manner to generate selectivity for depth sign from motion parallax. We also show, through simulations, that depth could be estimated from a population of such gain-modulated neurons. PMID:28739582

Grouping Inhibits Motion Fading by Giving Rise to Virtual Trackable Features

ERIC Educational Resources Information Center

Hsieh, P. -J.; Tse, P. U.

2007-01-01

After prolonged viewing of a slowly drifting or rotating pattern under strict fixation, the pattern appears to slow down and then momentarily stop. The authors show that grouping can slow down the process of "motion fading," suggesting that cortical configural form analysis interacts with the computation of motion signals during motion fading. The…

47 CFR 7.23 - Actions by the Commission on its own motion.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Actions by the Commission on its own motion. 7... INTERACTIVE MENU SERVICES AND EQUIPMENT BY PEOPLE WITH DISABILITIES Enforcement § 7.23 Actions by the Commission on its own motion. The Commission may on its own motion conduct such inquiries and hold such...

47 CFR 7.23 - Actions by the Commission on its own motion.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 1 2011-10-01 2011-10-01 false Actions by the Commission on its own motion. 7... INTERACTIVE MENU SERVICES AND EQUIPMENT BY PEOPLE WITH DISABILITIES Enforcement § 7.23 Actions by the Commission on its own motion. The Commission may on its own motion conduct such inquiries and hold such...

Motion and force control for multiple cooperative manipulators

NASA Technical Reports Server (NTRS)

Wen, John T.; Kreutz, Kenneth

1989-01-01

The motion and force control of multiple robot arms manipulating a commonly held object is addressed. A general control paradigm that decouples the motion and force control problems is introduced. For motion control, there are three natural choices: (1) joint torques, (2) arm-tip force vectors, and (3) the acceleration of a generalized coordinate. Choice (1) allows a class of relatively model-independent control laws by exploiting the Hamiltonian structure of the open-loop system; (2) and (3) require the full model information but produce simpler problems. To resolve the nonuniqueness of the joint torques, two methods are introduced. If the arm and object models are available, the allocation of the desired end-effector control force to the joint actuators can be optimized; otherwise the internal force can be controlled about some set point. It is shown that effective force regulation can be achieved even if little model information is available.

A Compact VLSI System for Bio-Inspired Visual Motion Estimation.

PubMed

Shi, Cong; Luo, Gang

2018-04-01

This paper proposes a bio-inspired visual motion estimation algorithm based on motion energy, along with its compact very-large-scale integration (VLSI) architecture using low-cost embedded systems. The algorithm mimics motion perception functions of retina, V1, and MT neurons in a primate visual system. It involves operations of ternary edge extraction, spatiotemporal filtering, motion energy extraction, and velocity integration. Moreover, we propose the concept of confidence map to indicate the reliability of estimation results on each probing location. Our algorithm involves only additions and multiplications during runtime, which is suitable for low-cost hardware implementation. The proposed VLSI architecture employs multiple (frame, pixel, and operation) levels of pipeline and massively parallel processing arrays to boost the system performance. The array unit circuits are optimized to minimize hardware resource consumption. We have prototyped the proposed architecture on a low-cost field-programmable gate array platform (Zynq 7020) running at 53-MHz clock frequency. It achieved 30-frame/s real-time performance for velocity estimation on 160 × 120 probing locations. A comprehensive evaluation experiment showed that the estimated velocity by our prototype has relatively small errors (average endpoint error < 0.5 pixel and angular error < 10°) for most motion cases.

Multiple-camera/motion stereoscopy for range estimation in helicopter flight

NASA Technical Reports Server (NTRS)

Smith, Phillip N.; Sridhar, Banavar; Suorsa, Raymond E.

1993-01-01

Aiding the pilot to improve safety and reduce pilot workload by detecting obstacles and planning obstacle-free flight paths during low-altitude helicopter flight is desirable. Computer vision techniques provide an attractive method of obstacle detection and range estimation for objects within a large field of view ahead of the helicopter. Previous research has had considerable success by using an image sequence from a single moving camera to solving this problem. The major limitations of single camera approaches are that no range information can be obtained near the instantaneous direction of motion or in the absence of motion. These limitations can be overcome through the use of multiple cameras. This paper presents a hybrid motion/stereo algorithm which allows range refinement through recursive range estimation while avoiding loss of range information in the direction of travel. A feature-based approach is used to track objects between image frames. An extended Kalman filter combines knowledge of the camera motion and measurements of a feature's image location to recursively estimate the feature's range and to predict its location in future images. Performance of the algorithm will be illustrated using an image sequence, motion information, and independent range measurements from a low-altitude helicopter flight experiment.

Transmission Electron Microscope In Situ Straining Technique to Directly Observe Defects and Interfaces During Deformation in Magnesium

DOE PAGES

Morrow, Benjamin M.; Cerreta, E. K.; McCabe, R. J.; ...

2015-05-14

In-situ straining was used to study deformation behavior of hexagonal close-packed (hcp) metals.Twinning and dislocation motion, both essential to plasticity in hcp materials, were observed.Typically, these processes are characterized post-mortem by examining remnant microstructural features after straining has occurred. By imposing deformation during imaging, direct observation of active deformation mechanisms is possible. This work focuses on straining of structural metals in a transmission electron microscope (TEM), and a recently developed technique that utilizes familiar procedures and equipment to increase ease of experiments. In-situ straining in a TEM presents several advantages over conventional post-mortem characterization, most notably time-resolution of deformation andmore » streamlined identification of active deformation mechanisms. Drawbacks to the technique and applicability to other studies are also addressed. In-situ straining is used to study twin boundary motion in hcp magnesium. A {101¯2} twin was observed during tensile and compressive loading. Twin-dislocation interactions are directly observed. Notably, dislocations are observed to remain mobile, even after multiple interactions with twin boundaries, a result which suggests that Basinki’s dislocation transformation mechanism by twinning is not present in hcp metals. The coupling of in-situ straining with traditional post-mortem characterization yields more detailed information about material behavior during deformation than either technique alone.« less

Motion Pattern Encapsulation for Data-Driven Constraint-Based Motion Editing

NASA Astrophysics Data System (ADS)

Carvalho, Schubert R.; Boulic, Ronan; Thalmann, Daniel

The growth of motion capture systems have contributed to the proliferation of human motion database, mainly because human motion is important in many applications, ranging from games entertainment and films to sports and medicine. However, the captured motions normally attend specific needs. As an effort for adapting and reusing captured human motions in new tasks and environments and improving the animator's work, we present and discuss a new data-driven constraint-based animation system for interactive human motion editing. This method offers the compelling advantage that it provides faster deformations and more natural-looking motion results compared to goal-directed constraint-based methods found in the literature.

Neural mechanisms underlying sound-induced visual motion perception: An fMRI study.

PubMed

Hidaka, Souta; Higuchi, Satomi; Teramoto, Wataru; Sugita, Yoichi

2017-07-01

Studies of crossmodal interactions in motion perception have reported activation in several brain areas, including those related to motion processing and/or sensory association, in response to multimodal (e.g., visual and auditory) stimuli that were both in motion. Recent studies have demonstrated that sounds can trigger illusory visual apparent motion to static visual stimuli (sound-induced visual motion: SIVM): A visual stimulus blinking at a fixed location is perceived to be moving laterally when an alternating left-right sound is also present. Here, we investigated brain activity related to the perception of SIVM using a 7T functional magnetic resonance imaging technique. Specifically, we focused on the patterns of neural activities in SIVM and visually induced visual apparent motion (VIVM). We observed shared activations in the middle occipital area (V5/hMT), which is thought to be involved in visual motion processing, for SIVM and VIVM. Moreover, as compared to VIVM, SIVM resulted in greater activation in the superior temporal area and dominant functional connectivity between the V5/hMT area and the areas related to auditory and crossmodal motion processing. These findings indicate that similar but partially different neural mechanisms could be involved in auditory-induced and visually-induced motion perception, and neural signals in auditory, visual, and, crossmodal motion processing areas closely and directly interact in the perception of SIVM. Copyright © 2017 Elsevier B.V. All rights reserved.

"Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications

NASA Astrophysics Data System (ADS)

Marshall, J. R.

1999-09-01

The term "Coulombic viscosity" is introduced here to define an empirically observed phenomenon from experiments conducted in both microgravity, and in ground-based 1-g conditions. In the latter case, a sand attrition device was employed to test the longevity of aeolian materials by creating two intersecting grain-circulation paths or cells that would lead to most of the grain energy being expended on grain-to-grain collisions (simulating dune systems). In the areas in the device where gravitationally-driven grain-slurries recycled the sand, the slurries moved with a boundary-layer impeded motion down the chamber walls. Excessive electrostatic charging of the grains during these experiments was prevented by the use of an a.c. corona (created by a Tesla coil) through which the grains passed on every cycle. This created both positive and negative ions which neutralized the triboelectrically-generated grain charges. When the corona was switched on, the velocity of the wall-attached slurries increased by a factor of two as approximately determined by direct observation. What appeared to be a freely-flowing slurry of grains impeded only by intergranular mechanical friction, had obviously been significantly retarded in its motion by electrostatic forces between the grains; with the charging reduced, the grains were able to move past one another without a flow "viscosity" imposed by the Coulombic intergranular forces. A similar phenomenon was observed during microgravity experiments aboard Space Shuttle in USML-1 & USML-2 spacelabs where freely-suspended clouds of sand were being investigated for their potential to for-m aggregates. In this environment, the grains were also charged electrostatically (by natural processes prior to flight), but were free from the intervention of gravity in their interactions. The grains were dispersed into dense clouds by bursts of air turbulence and allowed to form aggregates as the ballistic and turbulent motions damped out. During this very brief (30-60 sec) damping period, motion of the grains was observed to be retarded by the electrostatic interactions. The fact that the grains almost instantly formed aggregates was evidence that their ballistic motions had been constrained and redirected by the dipole-dipole interactions that led to filamentary aggregate development. Undoubtedly, the "Coulombic viscosity" of the cloud assisted in damping grain motion so rapidly. The electrostatically-induced grain-cloud viscosity or drag exerted on grain motion, is a complex function of three major parameters: charge magnitude, charge sign, and mean intergranular distance. The above experiments illustrate one particular type of granular behavior. The discussion here will therefore be restricted to drag relationships: (a) between grains that are naturally charged triboelectrically and thus exhibit dipole-dipole attractions between one another even if there are slight net charges present (which can be overwhelmed by dipole coupling at short distances), and (b) between grains that are densely spaced where the intergranular distance varies between zero and some value (usually tens or hundreds of grain diameters) that permits each grain to detect the dipole moment of another grain -- the distance is not so great that other grains appears as neutral electrical "singularities. I. Aeolian transport: During motion of grains in a saltation cloud (on Earth, Mars, or Venus), triboelectric charging must occur as a result of multiple grain contacts, and by friction with the entraining air. A situation might develop that is similar to the one described above in the attrition device: grain motion becoming significantly retarded (reduced flux) as grains find it increasingly difficult to either separate from the surface, or to pass one another without Coulombic retarding forces. A "Coulombic drag" will exist at flux initiation and increase with time to work in direct opposition to the aerodynamic drag that drives the grain motion. It is predicted that this will lead to an increase with time of both the aerodynamic and bed-dilatancy thresholds (3). Because of Paschen discharge effects in the martian atmosphere, the electrostatic charging in a saltation cloud may be partially abated, but this will lead to greater grain mobility, more charging, and thus to a charge-discharge steady state mediated by mechanical interactions. II. Dry colluvial systems: Sand avalanches on dunes, dry debris flows, talus flows, avalanches, and pyroclastic surges are examples of gravity-driven, dense granular flows where rock/grain fragmentation and grain-to-grain interactions cause triboelectrification (sometimes augmented by other electrical charging processes), and where the grain densities of the systems are such that strong dipole-dipole interactions between grains might be expected to be present. Because it is expected that the Coulombic forces between grains will cause a sluggishness or enhanced granular-flow viscosity, the motion of a grain mass will be retarded or damped so that this will assist, ultimately, in terminating the flow. The greatest Coulombic viscosity will be created in the most highly charged systems, which will also be the most energetic. Thus, grain flows have some tendency to be self-limiting by internal energy partitioning; gravitational potential is converted to Coulombic potential, which manifests itself as a drag force between the grains. III. Volcanic eruption plumes and impact ejecta curtains: The violence of these systems leads to powerful electrical charging of particulates. Lightning storms emanating from volcanic plumes are a testimony to the levels of charging. As pyroclastic grains interact forcefully and frequently within eruption plumes, it is reasonable to predict that the internal turbulent motions of the plume will be significantly damped by the Coulombic viscosity exerted by grain charges. Additional information is contained in the original.

"Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications

NASA Technical Reports Server (NTRS)

Marshall, J. R.

1999-01-01

The term "Coulombic viscosity" is introduced here to define an empirically observed phenomenon from experiments conducted in both microgravity, and in ground-based 1-g conditions. In the latter case, a sand attrition device was employed to test the longevity of aeolian materials by creating two intersecting grain-circulation paths or cells that would lead to most of the grain energy being expended on grain-to-grain collisions (simulating dune systems). In the areas in the device where gravitationally-driven grain-slurries recycled the sand, the slurries moved with a boundary-layer impeded motion down the chamber walls. Excessive electrostatic charging of the grains during these experiments was prevented by the use of an a.c. corona (created by a Tesla coil) through which the grains passed on every cycle. This created both positive and negative ions which neutralized the triboelectrically-generated grain charges. When the corona was switched on, the velocity of the wall-attached slurries increased by a factor of two as approximately determined by direct observation. What appeared to be a freely-flowing slurry of grains impeded only by intergranular mechanical friction, had obviously been significantly retarded in its motion by electrostatic forces between the grains; with the charging reduced, the grains were able to move past one another without a flow "viscosity" imposed by the Coulombic intergranular forces. A similar phenomenon was observed during microgravity experiments aboard Space Shuttle in USML-1 & USML-2 spacelabs where freely-suspended clouds of sand were being investigated for their potential to for-m aggregates. In this environment, the grains were also charged electrostatically (by natural processes prior to flight), but were free from the intervention of gravity in their interactions. The grains were dispersed into dense clouds by bursts of air turbulence and allowed to form aggregates as the ballistic and turbulent motions damped out. During this very brief (30-60 sec) damping period, motion of the grains was observed to be retarded by the electrostatic interactions. The fact that the grains almost instantly formed aggregates was evidence that their ballistic motions had been constrained and redirected by the dipole-dipole interactions that led to filamentary aggregate development. Undoubtedly, the "Coulombic viscosity" of the cloud assisted in damping grain motion so rapidly. The electrostatically-induced grain-cloud viscosity or drag exerted on grain motion, is a complex function of three major parameters: charge magnitude, charge sign, and mean intergranular distance. The above experiments illustrate one particular type of granular behavior. The discussion here will therefore be restricted to drag relationships: (a) between grains that are naturally charged triboelectrically and thus exhibit dipole-dipole attractions between one another even if there are slight net charges present (which can be overwhelmed by dipole coupling at short distances), and (b) between grains that are densely spaced where the intergranular distance varies between zero and some value (usually tens or hundreds of grain diameters) that permits each grain to detect the dipole moment of another grain -- the distance is not so great that other grains appears as neutral electrical "singularities. I. Aeolian transport: During motion of grains in a saltation cloud (on Earth, Mars, or Venus), triboelectric charging must occur as a result of multiple grain contacts, and by friction with the entraining air. A situation might develop that is similar to the one described above in the attrition device: grain motion becoming significantly retarded (reduced flux) as grains find it increasingly difficult to either separate from the surface, or to pass one another without Coulombic retarding forces. A "Coulombic drag" will exist at flux initiation and increase with time to work in direct opposition to the aerodynamic drag that drives the grain motion. It is predicted that this will lead to an increase with time of both the aerodynamic and bed-dilatancy thresholds (3). Because of Paschen discharge effects in the martian atmosphere, the electrostatic charging in a saltation cloud may be partially abated, but this will lead to greater grain mobility, more charging, and thus to a charge-discharge steady state mediated by mechanical interactions. II. Dry colluvial systems: Sand avalanches on dunes, dry debris flows, talus flows, avalanches, and pyroclastic surges are examples of gravity-driven, dense granular flows where rock/grain fragmentation and grain-to-grain interactions cause triboelectrification (sometimes augmented by other electrical charging processes), and where the grain densities of the systems are such that strong dipole-dipole interactions between grains might be expected to be present. Because it is expected that the Coulombic forces between grains will cause a sluggishness or enhanced granular-flow viscosity, the motion of a grain mass will be retarded or damped so that this will assist, ultimately, in terminating the flow. The greatest Coulombic viscosity will be created in the most highly charged systems, which will also be the most energetic. Thus, grain flows have some tendency to be self-limiting by internal energy partitioning; gravitational potential is converted to Coulombic potential, which manifests itself as a drag force between the grains. III. Volcanic eruption plumes and impact ejecta curtains: The violence of these systems leads to powerful electrical charging of particulates. Lightning storms emanating from volcanic plumes are a testimony to the levels of charging. As pyroclastic grains interact forcefully and frequently within eruption plumes, it is reasonable to predict that the internal turbulent motions of the plume will be significantly damped by the Coulombic viscosity exerted by grain charges. Additional information is contained in the original.

Reducing the net torque and flow ripple effects of multiple hydraulic piston motor drives

NASA Technical Reports Server (NTRS)

Bartos, R. D.

1992-01-01

The torque and flow ripple effects which result when multiple hydraulic motors are used to drive a single motion of a mechanical device can significantly affect the way in which the device performs. This article presents a mathematical model describing the torque and flow ripple effects of a bent-axis hydraulic piston motor. The model is used to show how the ripple magnitude can be reduced when multiple motors are used to drive a motion. A discussion of the hydraulic servo system of the 70-m antennas located with the Deep Space Network is included to demonstrate the application of the concepts presented.

Separate Perceptual and Neural Processing of Velocity- and Disparity-Based 3D Motion Signals

PubMed Central

Czuba, Thaddeus B.; Cormack, Lawrence K.; Huk, Alexander C.

2016-01-01

Although the visual system uses both velocity- and disparity-based binocular information for computing 3D motion, it is unknown whether (and how) these two signals interact. We found that these two binocular signals are processed distinctly at the levels of both cortical activity in human MT and perception. In human MT, adaptation to both velocity-based and disparity-based 3D motions demonstrated direction-selective neuroimaging responses. However, when adaptation to one cue was probed using the other cue, there was no evidence of interaction between them (i.e., there was no “cross-cue” adaptation). Analogous psychophysical measurements yielded correspondingly weak cross-cue motion aftereffects (MAEs) in the face of very strong within-cue adaptation. In a direct test of perceptual independence, adapting to opposite 3D directions generated by different binocular cues resulted in simultaneous, superimposed, opposite-direction MAEs. These findings suggest that velocity- and disparity-based 3D motion signals may both flow through area MT but constitute distinct signals and pathways. SIGNIFICANCE STATEMENT Recent human neuroimaging and monkey electrophysiology have revealed 3D motion selectivity in area MT, which is driven by both velocity-based and disparity-based 3D motion signals. However, to elucidate the neural mechanisms by which the brain extracts 3D motion given these binocular signals, it is essential to understand how—or indeed if—these two binocular cues interact. We show that velocity-based and disparity-based signals are mostly separate at the levels of both fMRI responses in area MT and perception. Our findings suggest that the two binocular cues for 3D motion might be processed by separate specialized mechanisms. PMID:27798134

Separate Perceptual and Neural Processing of Velocity- and Disparity-Based 3D Motion Signals.

PubMed

Joo, Sung Jun; Czuba, Thaddeus B; Cormack, Lawrence K; Huk, Alexander C

2016-10-19

Although the visual system uses both velocity- and disparity-based binocular information for computing 3D motion, it is unknown whether (and how) these two signals interact. We found that these two binocular signals are processed distinctly at the levels of both cortical activity in human MT and perception. In human MT, adaptation to both velocity-based and disparity-based 3D motions demonstrated direction-selective neuroimaging responses. However, when adaptation to one cue was probed using the other cue, there was no evidence of interaction between them (i.e., there was no "cross-cue" adaptation). Analogous psychophysical measurements yielded correspondingly weak cross-cue motion aftereffects (MAEs) in the face of very strong within-cue adaptation. In a direct test of perceptual independence, adapting to opposite 3D directions generated by different binocular cues resulted in simultaneous, superimposed, opposite-direction MAEs. These findings suggest that velocity- and disparity-based 3D motion signals may both flow through area MT but constitute distinct signals and pathways. Recent human neuroimaging and monkey electrophysiology have revealed 3D motion selectivity in area MT, which is driven by both velocity-based and disparity-based 3D motion signals. However, to elucidate the neural mechanisms by which the brain extracts 3D motion given these binocular signals, it is essential to understand how-or indeed if-these two binocular cues interact. We show that velocity-based and disparity-based signals are mostly separate at the levels of both fMRI responses in area MT and perception. Our findings suggest that the two binocular cues for 3D motion might be processed by separate specialized mechanisms. Copyright © 2016 the authors 0270-6474/16/3610791-12$15.00/0.

Piezoelectric actuator uses sequentially-excited multiple elements: A concept

NASA Technical Reports Server (NTRS)

Sabelman, E. E.

1972-01-01

Utilizing arrays of sequentially-excited piezoelectric elements to provide motion in a nonmagnetic motor provide built-in redundancy and long life required for deployment or actuation of devices on spacecraft. Linear-motion motor devices can also be fabricated.

The effects of particle shape, size, and interaction on colloidal glasses and gels

NASA Astrophysics Data System (ADS)

Kramb, Ryan C.

Using multiple step seeded emulsion polymerization reactions, colloid particles of tunable shape are synthesized from polystyrene. In all, four particle shapes are studied referred to as spheres (S), heteronuclear dicolloids (hDC), symmetric homonuclear dicolloids (sDC), and tricolloids (TC). Two size ranges of particles are studied with approximate diameters in the range of 200-300nm and 1.1-1.3mum. The solvent ionic strength is varied from 10 -3M to 1M resulting in particle interaction potentials that range from repulsive to attractive. The effect of anisotropic shape is found to increase the glass transition volume fraction (φg) in good agreement with activated naive Mode Coupling Theory (nMCT) calculations. Differences in φg and the linear elastic modulus (G0') due to particle shape can be understood in terms of the Random Close Packed volume fraction (φRCP ) for each shape; φRCP- φg is a constant. In addition, a reentrant phase diagram is found for S and sDC particles with a maximum in the fluid state volume fraction found at weakly attractive interaction potential, in agreement well with theoretical calculations. Nonlinear rheology and yielding behavior of repulsive and attractive spheres and anisotropic particles are examined and understood in terms of barriers constraining motion. The barriers are due to interparticle bonds or cages constraining translational or rotational motion. Yield stress has similar volume fraction dependence as G 0' and a similar framework is used to understand differences due to particle shape and interaction. For larger particles, the effects of shape and interaction are studied with respect to dynamic yielding and shear thickening. The dynamic yield stress is found to increase with volume fraction while the stress at thickening is constant. The intersection of these indicates a possible jamming point below φRCP.

Dye-enhanced visualization of rat whiskers for behavioral studies.

PubMed

Rigosa, Jacopo; Lucantonio, Alessandro; Noselli, Giovanni; Fassihi, Arash; Zorzin, Erik; Manzino, Fabrizio; Pulecchi, Francesca; Diamond, Mathew E

2017-06-14

Visualization and tracking of the facial whiskers is required in an increasing number of rodent studies. Although many approaches have been employed, only high-speed videography has proven adequate for measuring whisker motion and deformation during interaction with an object. However, whisker visualization and tracking is challenging for multiple reasons, primary among them the low contrast of the whisker against its background. Here, we demonstrate a fluorescent dye method suitable for visualization of one or more rat whiskers. The process makes the dyed whisker(s) easily visible against a dark background. The coloring does not influence the behavioral performance of rats trained on a vibrissal vibrotactile discrimination task, nor does it affect the whiskers' mechanical properties.

Trapped Ion Qubits

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

Maunz, Peter; Wilhelm, Lukas

Qubits can be encoded in clock states of trapped ions. These states are well isolated from the environment resulting in long coherence times [1] while enabling efficient high-fidelity qubit interactions mediated by the Coulomb coupled motion of the ions in the trap. Quantum states can be prepared with high fidelity and measured efficiently using fluorescence detection. State preparation and detection with 99.93% fidelity have been realized in multiple systems [1,2]. Single qubit gates have been demonstrated below rigorous fault-tolerance thresholds [1,3]. Two qubit gates have been realized with more than 99.9% fidelity [4,5]. Quantum algorithms have been demonstrated on systemsmore » of 5 to 15 qubits [6–8].« less

Improved workflow for quantification of left ventricular volumes and mass using free-breathing motion corrected cine imaging.

PubMed

Cross, Russell; Olivieri, Laura; O'Brien, Kendall; Kellman, Peter; Xue, Hui; Hansen, Michael

2016-02-25

Traditional cine imaging for cardiac functional assessment requires breath-holding, which can be problematic in some situations. Free-breathing techniques have relied on multiple averages or real-time imaging, producing images that can be spatially and/or temporally blurred. To overcome this, methods have been developed to acquire real-time images over multiple cardiac cycles, which are subsequently motion corrected and reformatted to yield a single image series displaying one cardiac cycle with high temporal and spatial resolution. Application of these algorithms has required significant additional reconstruction time. The use of distributed computing was recently proposed as a way to improve clinical workflow with such algorithms. In this study, we have deployed a distributed computing version of motion corrected re-binning reconstruction for free-breathing evaluation of cardiac function. Twenty five patients and 25 volunteers underwent cardiovascular magnetic resonance (CMR) for evaluation of left ventricular end-systolic volume (ESV), end-diastolic volume (EDV), and end-diastolic mass. Measurements using motion corrected re-binning were compared to those using breath-held SSFP and to free-breathing SSFP with multiple averages, and were performed by two independent observers. Pearson correlation coefficients and Bland-Altman plots tested agreement across techniques. Concordance correlation coefficient and Bland-Altman analysis tested inter-observer variability. Total scan plus reconstruction times were tested for significant differences using paired t-test. Measured volumes and mass obtained by motion corrected re-binning and by averaged free-breathing SSFP compared favorably to those obtained by breath-held SSFP (r = 0.9863/0.9813 for EDV, 0.9550/0.9685 for ESV, 0.9952/0.9771 for mass). Inter-observer variability was good with concordance correlation coefficients between observers across all acquisition types suggesting substantial agreement. Both motion corrected re-binning and averaged free-breathing SSFP acquisition and reconstruction times were shorter than breath-held SSFP techniques (p < 0.0001). On average, motion corrected re-binning required 3 min less than breath-held SSFP imaging, a 37% reduction in acquisition and reconstruction time. The motion corrected re-binning image reconstruction technique provides robust cardiac imaging that can be used for quantification that compares favorably to breath-held SSFP as well as multiple average free-breathing SSFP, but can be obtained in a fraction of the time when using cloud-based distributed computing reconstruction.

Inertial Sensor-Based Touch and Shake Metaphor for Expressive Control of 3D Virtual Avatars

PubMed Central

Patil, Shashidhar; Chintalapalli, Harinadha Reddy; Kim, Dubeom; Chai, Youngho

2015-01-01

In this paper, we present an inertial sensor-based touch and shake metaphor for expressive control of a 3D virtual avatar in a virtual environment. An intuitive six degrees-of-freedom wireless inertial motion sensor is used as a gesture and motion control input device with a sensor fusion algorithm. The algorithm enables user hand motions to be tracked in 3D space via magnetic, angular rate, and gravity sensors. A quaternion-based complementary filter is implemented to reduce noise and drift. An algorithm based on dynamic time-warping is developed for efficient recognition of dynamic hand gestures with real-time automatic hand gesture segmentation. Our approach enables the recognition of gestures and estimates gesture variations for continuous interaction. We demonstrate the gesture expressivity using an interactive flexible gesture mapping interface for authoring and controlling a 3D virtual avatar and its motion by tracking user dynamic hand gestures. This synthesizes stylistic variations in a 3D virtual avatar, producing motions that are not present in the motion database using hand gesture sequences from a single inertial motion sensor. PMID:26094629

Teaching an Old Robot New Tricks: Learning Novel Tasks via Interaction with People and Things

DTIC Science & Technology

2003-06-01

visions behind the Cog Project were to build a "robot baby ", which could interact with people and objects, imitate the motions of its teachers, and even...though. A very elaborate animatronic motor controller can produce very life-like canned motion, although the controller itself bears little resemblance

Development of a novel remote‐controlled and self‐contained audiovisual‐aided interactive system for immobilizing claustrophobic patients

PubMed Central

Ju, Harang; Kim, Siyong; Read, Paul; Trifiletti, Daniel; Harrell, Andrew; Libby, Bruce

2015-01-01

In radiotherapy, only a few immobilization systems, such as open‐face mask and head mold with a bite plate, are available for claustrophobic patients with a certain degree of discomfort. The purpose of this study was to develop a remote‐controlled and self‐contained audiovisual (AV)‐aided interactive system with the iPad mini with Retina display for intrafractional motion management in brain/H&N (head and neck) radiotherapy for claustrophobic patients. The self‐contained, AV‐aided interactive system utilized two tablet computers: one for AV‐aided interactive guidance for the subject and the other for remote control by an operator. The tablet for audiovisual guidance traced the motion of a colored marker using the built‐in front‐facing camera, and the remote control tablet at the control room used infrastructure Wi‐Fi networks for real‐time communication with the other tablet. In the evaluation, a programmed QUASAR motion phantom was used to test the temporal and positional accuracy and resolution. Position data were also obtained from ten healthy volunteers with and without guidance to evaluate the reduction of intrafractional head motion in simulations of a claustrophobic brain or H&N case. In the phantom study, the temporal and positional resolution was 24 Hz and 0.2 mm. In the volunteer study, the average superior–inferior and right–left displacement was reduced from 1.9 mm to 0.3 mm and from 2.2 mm to 0.2 mm with AV‐aided interactive guidance, respectively. The superior–inferior and right–left positional drift was reduced from 0.5 mm/min to 0.1 mm/min and from 0.4 mm/min to 0.04 mm/min with audiovisual‐aided interactive guidance. This study demonstrated a reduction in intrafractional head motion using a remote‐controlled and self‐contained AV‐aided interactive system of iPad minis with Retina display, easily obtainable and cost‐effective tablet computers. This approach can potentially streamline clinical flow for claustrophobic patients without a head mask and also allows patients to practice self‐motion management before radiation treatment delivery. PACS number: 87.55.Gh

An Interface for Specifying Rigid-Body Motions for CFD Applications

NASA Technical Reports Server (NTRS)

Murman, Scott M.; Chan, William; Aftosmis, Michael; Meakin, Robert L.; Kwak, Dochan (Technical Monitor)

2003-01-01

An interface for specifying rigid-body motions for CFD applications is presented. This interface provides a means of describing a component hierarchy in a geometric configuration, as well as the motion (prescribed or six-degree-of-freedom) associated with any component. The interface consists of a general set of datatypes, along with rules for their interaction, and is designed to be flexible in order to evolve as future needs dictate. The specification is currently implemented with an XML file format which is portable across platforms and applications. The motion specification is capable of describing general rigid body motions, and eliminates the need to write and compile new code within the application software for each dynamic configuration, allowing client software to automate dynamic simulations. The interface is integrated with a GUI tool which allows rigid body motions to be prescribed and verified interactively, promoting access to non-expert users. Illustrative examples, as well as the raw XML source of the file specifications, are included.

“What Women Like”: Influence of Motion and Form on Esthetic Body Perception

PubMed Central

Cazzato, Valentina; Siega, Serena; Urgesi, Cosimo

2012-01-01

Several studies have shown the distinct contribution of motion and form to the esthetic evaluation of female bodies. Here, we investigated how variations of implied motion and body size interact in the esthetic evaluation of female and male bodies in a sample of young healthy women. Participants provided attractiveness, beauty, and liking ratings for the shape and posture of virtual renderings of human bodies with variable body size and implied motion. The esthetic judgments for both shape and posture of human models were influenced by body size and implied motion, with a preference for thinner and more dynamic stimuli. Implied motion, however, attenuated the impact of extreme body size on the esthetic evaluation of body postures, while body size variations did not affect the preference for more dynamic stimuli. Results show that body form and action cues interact in esthetic perception, but the final esthetic appreciation of human bodies is predicted by a mixture of perceptual and affective evaluative components. PMID:22866044

Amplified effect of Brownian motion in bacterial near-surface swimming

PubMed Central

Li, Guanglai; Tam, Lick-Kong; Tang, Jay X.

2008-01-01

Brownian motion influences bacterial swimming by randomizing displacement and direction. Here, we report that the influence of Brownian motion is amplified when it is coupled to hydrodynamic interaction. We examine swimming trajectories of the singly flagellated bacterium Caulobacter crescentus near a glass surface with total internal reflection fluorescence microscopy and observe large fluctuations over time in the distance of the cell from the solid surface caused by Brownian motion. The observation is compared with computer simulation based on analysis of relevant physical factors, including electrostatics, van der Waals force, hydrodynamics, and Brownian motion. The simulation reproduces the experimental findings and reveals contribution from fluctuations of the cell orientation beyond the resolution of present observation. Coupled with hydrodynamic interaction between the bacterium and the boundary surface, the fluctuations in distance and orientation subsequently lead to variation of the swimming speed and local radius of curvature of swimming trajectory. These results shed light on the fundamental roles of Brownian motion in microbial motility, nutrient uptake, and adhesion. PMID:19015518

The Effects of Towfish Motion on Sidescan Sonar Images: Extension to a Multiple-Beam Device

DTIC Science & Technology

1994-02-01

simulation, the raw simulated sidescan image is formed from pixels G , which are the sum of energies E,", assigned to the nearest range- bin k as noted in...for stable motion at constant velocity V0, are applied to (divided into) the G ,, and the simulated sidescan image is ready to display. Maximal energy...limitation is likely to apply to all multiple-beam sonais of similar construction. The yaw correction was incorporated in the MBEAM model by an

The effect of occlusion therapy on motion perception deficits in amblyopia.

PubMed

Giaschi, Deborah; Chapman, Christine; Meier, Kimberly; Narasimhan, Sathyasri; Regan, David

2015-09-01

There is growing evidence for deficits in motion perception in amblyopia, but these are rarely assessed clinically. In this prospective study we examined the effect of occlusion therapy on motion-defined form perception and multiple-object tracking. Participants included children (3-10years old) with unilateral anisometropic and/or strabismic amblyopia who were currently undergoing occlusion therapy and age-matched control children with normal vision. At the start of the study, deficits in motion-defined form perception were present in at least one eye in 69% of the children with amblyopia. These deficits were still present at the end of the study in 55% of the amblyopia group. For multiple-object tracking, deficits were present initially in 64% and finally in 55% of the children with amblyopia, even after completion of occlusion therapy. Many of these deficits persisted in spite of an improvement in amblyopic eye visual acuity in response to occlusion therapy. The prevalence of motion perception deficits in amblyopia as well as their resistance to occlusion therapy, support the need for new approaches to amblyopia treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Photo-consistency registration of a 4D cardiac motion model to endoscopic video for image guidance of robotic coronary artery bypass

NASA Astrophysics Data System (ADS)

Figl, Michael; Rueckert, Daniel; Edwards, Eddie

2009-02-01

The aim of the work described in this paper is registration of a 4D preoperative motion model of the heart to the video view of the patient through the intraoperative endoscope. The heart motion is cyclical and can be modelled using multiple reconstructions of cardiac gated coronary CT. We propose the use of photoconsistency between the two views through the da Vinci endoscope to align to the preoperative heart surface model from CT. The temporal alignment from the video to the CT model could in principle be obtained from the ECG signal. We propose averaging of the photoconsistency over the cardiac cycle to improve the registration compared to a single view. Though there is considerable motion of the heart, after correct temporal alignment we suggest that the remaining motion should be close to rigid. Results are presented for simulated renderings and for real video of a beating heart phantom. We found much smoother sections at the minimum when using multiple phases for the registration, furthermore convergence was found to be better when more phases are used.

A multivariate assessment of the effect of the laboratory homework component of a microcomputer-based laboratory for a college freshman physics course

NASA Astrophysics Data System (ADS)

Ramlo, Susan E.

Microcomputer-based laboratories (MBLs) have been defined as software that uses an electronic probe to collect information about a physical system and then converts that information into graphical systems in real-time. Realtime Physics Laboratories (RTP) are an example of laboratories that combine the use of MBLs with collaboration and guided-inquiry. RTP Mechanics Laboratories include both laboratory activities and laboratory homework for the first semester of college freshman physics courses. Prior research has investigated the effectiveness of the RTP laboratories as a package (laboratory activities with laboratory homework). In this study, an experimental-treatment had students complete both the RTP laboratory activity and the associated laboratory homework during the same laboratory period. Observations of this treatment indicated that students primarily consulted the laboratory instructor and referred to their completed laboratory activity while completing the homework in their collaborative groups. In the control-treatment, students completed the laboratory homework outside the laboratory period. Measures of force and motion conceptual understanding included the Force and Motion Conceptual Understanding (FMCE), a 47 multiple-choice question test. Analyses of the FMCE indicated that it is both a reliable and a valid measure of force and motion conceptual understanding. A distinct, five-factor structure for the FMCE post-test answers reflected specific concepts related to force and motion. However, the three FMCE pretest factors were less distinct. Analysis of the experimental-treatment, compared to a control-treatment, included multiple regression analysis with covariates of age, prior physics-classroom experience, and the three FMCE pretest factors. Criterion variables included each of the five post-test factors, the total laboratory homework score, and a group of seven exam questions. The results were all positive, in favor of the experimental-treatment. However, the results were significant only with the criterions of the FMCE post-test factor "Concepts Regarding Newton's First and Second Laws" and the laboratory homework score. The interaction between the treatments and prior physics-classroom experience was not significant. Implications of the qualitative and quantitative findings are discussed.

Rupture dynamics along dipping thrust faults: free surface interaction and the case of Tohoku earthquake

NASA Astrophysics Data System (ADS)

Festa, Gaetano; Scala, Antonio; Vilotte, Jean-Pierre

2017-04-01

To address the influence of the free surface interaction on rupture propagating along subduction zones, we numerically investigate dynamic interactions, involving coupling between normal and shear tractions, between in-plane rupture propagating along dipping thrust faults and a free surface for different structural and geometrical conditions. When the rupture occurs along reverse fault with a dip angle different from 90° the symmetry is broken as an effect of slip-induced normal stress perturbations and a larger ground motion is evidenced on the hanging wall. The ground motion is amplified by multiple reflections of waves trapped between the fault and the free surface. This effect is shown to occur when the rupture tip lies on the vertical below the intersection between the S-wave front and the surface that is when waves along the surface start to interact with the rupture front. This interaction is associated with a finite region where the rupture advances in a massive regime preventing the shrinking of the process zone and the emission of high-frequency radiation. The smaller the dip angle the larger co-seismic slip in the shallow part as an effect of the significant break of symmetry. Radiation from shallow part is still depleted in high frequencies due to the massive propagating regime and the interaction length dominating the rupture dynamics. Instantaneous shear response to normal traction perturbations may lead to unstable solutions as in the case of bimaterial rupture. A parametric study has been performed to analyse the effects of a regularised shear traction response to normal traction variations. Finally the case of Tohoku earthquake is considered and we present 2D along-dip numerical results. At first order the larger slip close to the trench can be ascribed to the break of symmetry and the interaction with free surface. When shear/normal coupling is properly regularised the signal from the trench is depleted in high frequencies whereas during deep propagation high-frequency radiations emerge associated to geometrical and structural complexities or to frictional strength asperities.

SOCR Motion Charts: An Efficient, Open-Source, Interactive and Dynamic Applet for Visualizing Longitudinal Multivariate Data

PubMed Central

Al-Aziz, Jameel; Christou, Nicolas; Dinov, Ivo D.

2011-01-01

The amount, complexity and provenance of data have dramatically increased in the past five years. Visualization of observed and simulated data is a critical component of any social, environmental, biomedical or scientific quest. Dynamic, exploratory and interactive visualization of multivariate data, without preprocessing by dimensionality reduction, remains a nearly insurmountable challenge. The Statistics Online Computational Resource (www.SOCR.ucla.edu) provides portable online aids for probability and statistics education, technology-based instruction and statistical computing. We have developed a new Java-based infrastructure, SOCR Motion Charts, for discovery-based exploratory analysis of multivariate data. This interactive data visualization tool enables the visualization of high-dimensional longitudinal data. SOCR Motion Charts allows mapping of ordinal, nominal and quantitative variables onto time, 2D axes, size, colors, glyphs and appearance characteristics, which facilitates the interactive display of multidimensional data. We validated this new visualization paradigm using several publicly available multivariate datasets including Ice-Thickness, Housing Prices, Consumer Price Index, and California Ozone Data. SOCR Motion Charts is designed using object-oriented programming, implemented as a Java Web-applet and is available to the entire community on the web at www.socr.ucla.edu/SOCR_MotionCharts. It can be used as an instructional tool for rendering and interrogating high-dimensional data in the classroom, as well as a research tool for exploratory data analysis. PMID:21479108

Parallel updating and weighting of multiple spatial maps for visual stability during whole body motion

PubMed Central

Medendorp, W. P.

2015-01-01

It is known that the brain uses multiple reference frames to code spatial information, including eye-centered and body-centered frames. When we move our body in space, these internal representations are no longer in register with external space, unless they are actively updated. Whether the brain updates multiple spatial representations in parallel, or whether it restricts its updating mechanisms to a single reference frame from which other representations are constructed, remains an open question. We developed an optimal integration model to simulate the updating of visual space across body motion in multiple or single reference frames. To test this model, we designed an experiment in which participants had to remember the location of a briefly presented target while being translated sideways. The behavioral responses were in agreement with a model that uses a combination of eye- and body-centered representations, weighted according to the reliability in which the target location is stored and updated in each reference frame. Our findings suggest that the brain simultaneously updates multiple spatial representations across body motion. Because both representations are kept in sync, they can be optimally combined to provide a more precise estimate of visual locations in space than based on single-frame updating mechanisms. PMID:26490289

Depletion force induced collective motion of microtubules driven by kinesin

NASA Astrophysics Data System (ADS)

Inoue, Daisuke; Mahmot, Bulbul; Kabir, Arif Md. Rashedul; Farhana, Tamanna Ishrat; Tokuraku, Kiyotaka; Sada, Kazuki; Konagaya, Akihiko; Kakugo, Akira

2015-10-01

Collective motion is a fascinating example of coordinated behavior of self-propelled objects, which is often associated with the formation of large scale patterns. Nowadays, the in vitro gliding assay is being considered a model system to experimentally investigate various aspects of group behavior and pattern formation by self-propelled objects. In the in vitro gliding assay, cytoskeletal filaments F-actin or microtubules are driven by the surface immobilized associated biomolecular motors myosin or dynein respectively. Although the F-actin/myosin or microtubule/dynein system was found to be promising in understanding the collective motion and pattern formation by self-propelled objects, the most widely used biomolecular motor system microtubule/kinesin could not be successfully employed so far in this regard. Failure in exhibiting collective motion by kinesin driven microtubules is attributed to the intrinsic properties of kinesin, which was speculated to affect the behavior of individual gliding microtubules and mutual interactions among them. In this work, for the first time, we have demonstrated the collective motion of kinesin driven microtubules by regulating the mutual interaction among the gliding microtubules, by employing a depletion force among them. Proper regulation of the mutual interaction among the gliding microtubules through the employment of the depletion force was found to allow the exhibition of collective motion and stream pattern formation by the microtubules. This work offers a universal means for demonstrating the collective motion using the in vitro gliding assay of biomolecular motor systems and will help obtain a meticulous understanding of the fascinating coordinated behavior and pattern formation by self-propelled objects.Collective motion is a fascinating example of coordinated behavior of self-propelled objects, which is often associated with the formation of large scale patterns. Nowadays, the in vitro gliding assay is being considered a model system to experimentally investigate various aspects of group behavior and pattern formation by self-propelled objects. In the in vitro gliding assay, cytoskeletal filaments F-actin or microtubules are driven by the surface immobilized associated biomolecular motors myosin or dynein respectively. Although the F-actin/myosin or microtubule/dynein system was found to be promising in understanding the collective motion and pattern formation by self-propelled objects, the most widely used biomolecular motor system microtubule/kinesin could not be successfully employed so far in this regard. Failure in exhibiting collective motion by kinesin driven microtubules is attributed to the intrinsic properties of kinesin, which was speculated to affect the behavior of individual gliding microtubules and mutual interactions among them. In this work, for the first time, we have demonstrated the collective motion of kinesin driven microtubules by regulating the mutual interaction among the gliding microtubules, by employing a depletion force among them. Proper regulation of the mutual interaction among the gliding microtubules through the employment of the depletion force was found to allow the exhibition of collective motion and stream pattern formation by the microtubules. This work offers a universal means for demonstrating the collective motion using the in vitro gliding assay of biomolecular motor systems and will help obtain a meticulous understanding of the fascinating coordinated behavior and pattern formation by self-propelled objects. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr02213d

Increased ISR operator capability utilizing a centralized 360° full motion video display

NASA Astrophysics Data System (ADS)

Andryc, K.; Chamberlain, J.; Eagleson, T.; Gottschalk, G.; Kowal, B.; Kuzdeba, P.; LaValley, D.; Myers, E.; Quinn, S.; Rose, M.; Rusiecki, B.

2012-06-01

In many situations, the difference between success and failure comes down to taking the right actions quickly. While the myriad of electronic sensors available today can provide data quickly, it may overload the operator; where only a contextualized centralized display of information and intuitive human interface can help to support the quick and effective decisions needed. If these decisions are to result in quick actions, then the operator must be able to understand all of the data of his environment. In this paper we present a novel approach in contextualizing multi-sensor data onto a full motion video real-time 360 degree imaging display. The system described could function as a primary display system for command and control in security, military and observation posts. It has the ability to process and enable interactive control of multiple other sensor systems. It enhances the value of these other sensors by overlaying their information on a panorama of the surroundings. Also, it can be used to interface to other systems including: auxiliary electro-optical systems, aerial video, contact management, Hostile Fire Indicators (HFI), and Remote Weapon Stations (RWS).

Human comfort response to dominant random motions in longitudinal modes of aircraft motion

NASA Technical Reports Server (NTRS)

Stone, R. W., Jr.

1980-01-01

The effects of random vertical and longitudinal accelerations and pitching velocity passenger ride comfort responses were examined on the NASA Langley Visual Motion Simulator. Effects of power spectral density shape were studied for motions where the peak was between 0 and 2 Hz. The subjective rating data and the physical motion data obtained are presented without interpretation or detailed analysis. There existed motions in all other degrees of freedom as well as the particular pair of longitudinal airplane motions studied. These unwanted motions, caused by the characteristics of the simulator may have introduced some interactive effects on passenger responses.

Light effects in the atomic-motion-induced Ramsey narrowing of dark resonances in wall-coated cells

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

Breschi, E.; Schori, C.; Di Domenico, G.

2010-12-15

We report on light shift and broadening in the atomic-motion-induced Ramsey narrowing of dark resonances prepared in alkali-metal vapors contained in wall-coated cells without buffer gas. The atomic-motion-induced Ramsey narrowing is due to the free motion of the polarized atomic spins in and out of the optical interaction region before spin relaxation. As a consequence of this effect, we observe a narrowing of the dark resonance linewidth as well as a reduction of the ground states' light shift when the volume of the interaction region decreases at constant optical intensity. The results can be intuitively interpreted as a dilution ofmore » the intensity effect similar to a pulsed interrogation due to the atomic motion. Finally the influence of this effect on the performance of compact atomic clocks is discussed.« less

Reduction of vortex induced forces and motion through surface roughness control

DOEpatents

Bernitsas, Michael M; Raghavan, Kamaldev

2014-04-01

Roughness is added to the surface of a bluff body in a relative motion with respect to a fluid. The amount, size, and distribution of roughness on the body surface is controlled passively or actively to modify the flow around the body and subsequently the Vortex Induced Forces and Motion (VIFM). The added roughness, when designed and implemented appropriately, affects in a predetermined way the boundary layer, the separation of the boundary layer, the level of turbulence, the wake, the drag and lift forces, and consequently the Vortex Induced Motion (VIM), and the fluid-structure interaction. The goal of surface roughness control is to decrease/suppress Vortex Induced Forces and Motion. Suppression is required when fluid-structure interaction becomes destructive as in VIM of flexible cylinders or rigid cylinders on elastic support, such as underwater pipelines, marine risers, tubes in heat exchangers, nuclear fuel rods, cooling towers, SPAR offshore platforms.

Nuclear quadrupole resonance lineshape analysis for different motional models: Stochastic Liouville approach

NASA Astrophysics Data System (ADS)

Kruk, D.; Earle, K. A.; Mielczarek, A.; Kubica, A.; Milewska, A.; Moscicki, J.

2011-12-01

A general theory of lineshapes in nuclear quadrupole resonance (NQR), based on the stochastic Liouville equation, is presented. The description is valid for arbitrary motional conditions (particularly beyond the valid range of perturbation approaches) and interaction strengths. It can be applied to the computation of NQR spectra for any spin quantum number and for any applied magnetic field. The treatment presented here is an adaptation of the "Swedish slow motion theory," [T. Nilsson and J. Kowalewski, J. Magn. Reson. 146, 345 (2000), 10.1006/jmre.2000.2125] originally formulated for paramagnetic systems, to NQR spectral analysis. The description is formulated for simple (Brownian) diffusion, free diffusion, and jump diffusion models. The two latter models account for molecular cooperativity effects in dense systems (such as liquids of high viscosity or molecular glasses). The sensitivity of NQR slow motion spectra to the mechanism of the motional processes modulating the nuclear quadrupole interaction is discussed.

Video stereolization: combining motion analysis with user interaction.

PubMed

Liao, Miao; Gao, Jizhou; Yang, Ruigang; Gong, Minglun

2012-07-01

We present a semiautomatic system that converts conventional videos into stereoscopic videos by combining motion analysis with user interaction, aiming to transfer as much as possible labeling work from the user to the computer. In addition to the widely used structure from motion (SFM) techniques, we develop two new methods that analyze the optical flow to provide additional qualitative depth constraints. They remove the camera movement restriction imposed by SFM so that general motions can be used in scene depth estimation-the central problem in mono-to-stereo conversion. With these algorithms, the user's labeling task is significantly simplified. We further developed a quadratic programming approach to incorporate both quantitative depth and qualitative depth (such as these from user scribbling) to recover dense depth maps for all frames, from which stereoscopic view can be synthesized. In addition to visual results, we present user study results showing that our approach is more intuitive and less labor intensive, while producing 3D effect comparable to that from current state-of-the-art interactive algorithms.

Heterogeneity and dynamics of the ligand recognition mode in purine-sensing riboswitches.

PubMed

Jain, Niyati; Zhao, Liang; Liu, John D; Xia, Tianbing

2010-05-04

High-resolution crystal structures and biophysical analyses of purine-sensing riboswitches have revealed that a network of hydrogen bonding interactions appear to be largey responsible for discrimination of cognate ligands against structurally related compounds. Here we report that by using femtosecond time-resolved fluorescence spectroscopy to capture the ultrafast decay dynamics of the 2-aminopurine base as the ligand, we have detected the presence of multiple conformations of the ligand within the binding pockets of one guanine-sensing and two adenine-sensing riboswitches. All three riboswitches have similar conformational distributions of the ligand-bound state. The known crystal structures represent the global minimum that accounts for 50-60% of the population, where there is no significant stacking interaction between the ligand and bases of the binding pocket, but the hydrogen-bonding cage collectively provides an electronic environment that promotes an ultrafast ( approximately 1 ps) charge transfer pathway. The ligand also samples multiple conformations in which it significantly stacks with either the adenine or the uracil bases of the A21-U75 and A52-U22 base pairs that form the ceiling and floor of the binding pocket, respectively, but favors the larger adenine bases. These alternative conformations with well-defined base stacking interactions are approximately 1-1.5 kcal/mol higher in DeltaG degrees than the global minimum and have distinct charge transfer dynamics within the picosecond to nanosecond time regime. Inside the pocket, the purine ligand undergoes dynamic motion on the low nanosecond time scale, sampling the multiple conformations based on time-resolved anisotropy decay dynamics. These results allowed a description of the energy landscape of the bound ligand with intricate details and demonstrated the elastic nature of the ligand recognition mode by the purine-sensing riboswitches, where there is a dynamic balance between hydrogen bonding and base stacking interactions, yielding the high affinity and specificity by the aptamer domain.

Relative motions of fragments of the split comets. III - A test of splitting and comets with suspected multiple nuclei

NASA Technical Reports Server (NTRS)

Sekanina, Z.

1979-01-01

A quantitative test of splitting for comets with suspected multiple nuclei has been formulated using a model which assumes the motions of cometary fragments to be due primarily to outgassing. The model expresses the relative motion of the cometary fragments in terms of the time of splitting and the differential force, which are determined by measurements of the position angle and the separation distance between fragments. The test is applied to 18 comets suspected of having multiple nuclei, of which the comets Sawerthal 1888 I, Campbell 1914 IV, Whipple-Fedtke-Tevzadze 1943 I, Honda 1955 V, Wild 1968 III and Tago-Sato-Kosaka 1969 IX were found to be clear cases of split comets and Davidson 1889 IV and Periodic Giacobini 1896 V were judged to be likely candidates. At least three of the secondary nuclei confirmed can be classified as short-lived companions, while only two appear to be persistent.

Nonlinear-drifted Brownian motion with multiple hidden states for remaining useful life prediction of rechargeable batteries

NASA Astrophysics Data System (ADS)

Wang, Dong; Zhao, Yang; Yang, Fangfang; Tsui, Kwok-Leung

2017-09-01

Brownian motion with adaptive drift has attracted much attention in prognostics because its first hitting time is highly relevant to remaining useful life prediction and it follows the inverse Gaussian distribution. Besides linear degradation modeling, nonlinear-drifted Brownian motion has been developed to model nonlinear degradation. Moreover, the first hitting time distribution of the nonlinear-drifted Brownian motion has been approximated by time-space transformation. In the previous studies, the drift coefficient is the only hidden state used in state space modeling of the nonlinear-drifted Brownian motion. Besides the drift coefficient, parameters of a nonlinear function used in the nonlinear-drifted Brownian motion should be treated as additional hidden states of state space modeling to make the nonlinear-drifted Brownian motion more flexible. In this paper, a prognostic method based on nonlinear-drifted Brownian motion with multiple hidden states is proposed and then it is applied to predict remaining useful life of rechargeable batteries. 26 sets of rechargeable battery degradation samples are analyzed to validate the effectiveness of the proposed prognostic method. Moreover, some comparisons with a standard particle filter based prognostic method, a spherical cubature particle filter based prognostic method and two classic Bayesian prognostic methods are conducted to highlight the superiority of the proposed prognostic method. Results show that the proposed prognostic method has lower average prediction errors than the particle filter based prognostic methods and the classic Bayesian prognostic methods for battery remaining useful life prediction.

Mathematical investigation of tsunami-like long waves interaction with submerge dike of different thickness

NASA Astrophysics Data System (ADS)

Zhiltsov, Konstantin; Kostyushin, Kirill; Kagenov, Anuar; Tyryshkin, Ilya

2017-11-01

This paper presents a mathematical investigation of the interaction of a long tsunami-type wave with a submerge dike. The calculations were performed by using the freeware package OpenFOAM. Unsteady two-dimensional Navier-Stokes equations were used for mathematical modeling of incompressible two-phase medium. The Volume of Fluid (VOF) method is used to capture the free surface of a liquid. The effects caused by long wave of defined amplitude motion through a submerged dike of varying thickness were discussed in detail. Numerical results show that after wave passing through the barrier, multiple vortex structures were formed behind. Intensity of vortex depended on the size of the barrier. The effectiveness of the submerge barrier was estimated by evaluating the wave reflection and transmission coefficients using the energy integral method. Then, the curves of the dependences of the reflection and transmission coefficients were obtained for the interaction of waves with the dike. Finally, it was confirmed that the energy of the wave could be reduced by more than 50% when it passed through the barrier.

Improved Swimming Performance in Hydrodynamically- coupled Airfoils

NASA Astrophysics Data System (ADS)

Heydari, Sina; Shelley, Michael J.; Kanso, Eva

2017-11-01

Collective motion is a widespread phenomenon in the animal kingdom from fish schools to bird flocks. Half of the known fish species are thought to exhibit schooling behavior during some phase of their life cycle. Schooling likely occurs to serve multiple purposes, including foraging for resources and protection from predators. Growing experimental and theoretical evidence supports the hypothesis that fish can benefit from the hydrodynamic interactions with their neighbors, but it is unclear whether this requires particular configurations or regulations. Here, we propose a physics-based approach that account for hydrodynamic interactions among swimmers based on the vortex sheet model. The benefit of this model is that it is scalable to a large number of swimmers. We start by examining the case of two swimmers, heaving plates, moving in parallel and in tandem. We find that for the same heaving amplitude and frequency, the coupled-swimmers move faster and more efficiently. This increase in velocity depends strongly on the configuration and separation distance between the swimmers. Our results are consistent with recent experimental findings on heaving airfoils and underline the role of fluid dynamic interactions in the collective behavior of swimmers.

Radio Frequency Signal Reception Via Distributed Wirelessly Networked Sensors Under Random Motion

DTIC Science & Technology

2009-09-01

100. Agent position in Pythagoras modeling in first phase level showing individual unit member interaction where each dot is an individual agent...181 Figure 101. Detail position in Pythagoras modeling in second phase showing detail group interaction where each blue dot is a unit...Table 5. Estimated reset time values and associated change percentage from Pythagoras agent motion

Reliability of Autonomic Responses and Malaise Across Multiple Motion Sickness Stimulation Tests

NASA Technical Reports Server (NTRS)

Stout, Cynthia S.; Toscano, William B.; Cowings, Patricia S.

1993-01-01

There is general agreement that a high degree of variability exists between subjects in their autonomic nervous system responses to motion sickness stimulation. Additionally, a paucity of data exists that examines the variability within an individual across repeated motion sickness tests. Investigators have also examined the relationship of autonomic responses to motion sickness development. These investigations have used analyses at discrete points in time to describe this relationship. This approach fails to address the time course of autonomic responses and malaise development throughout the motion sickness test. Our objectives were to examine the reliability of autonomic responses and malaise using the final minute of the motion sickness test across five testing occasions, to examine the reliability of the change in autonomic responses and the change in malaise across five testing occasions, and to examine the relationship between changes in autonomic responses and changes in malaise level across the entire motion sickness test. Our results indicate that, based on the final minute of testing, the autonomic responses of heart rate, blood volume pulse, and respiration rate are moderately stable across multiple tests. Changes in heart rate, blood volume pulse, respiration rate, and malaise throughout the test duration were less stable across the tests. We attribute this instability to variations in individual susceptibility and the error associated with estimating a measure of autonomic gain.

A Five-Dimensional Mathematical Model for Regional and Global Changes in Cardiac Uptake and Motion

NASA Astrophysics Data System (ADS)

Pretorius, P. H.; King, M. A.; Gifford, H. C.

2004-10-01

The objective of this work was to simultaneously introduce known regional changes in contraction pattern and perfusion to the existing gated Mathematical Cardiac Torso (MCAT) phantom heart model. We derived a simple integral to calculate the fraction of the ellipsoidal volume that makes up the left ventricle (LV), taking into account the stationary apex and the moving base. After calculating the LV myocardium volume of the existing beating heart model, we employed the property of conservation of mass to manipulate the LV ejection fraction to values ranging between 13.5% and 68.9%. Multiple dynamic heart models that differ in degree of LV wall thickening, base-to-apex motion, and ejection fraction, are thus available for use with the existing MCAT methodology. To introduce more complex regional LV contraction and perfusion patterns, we used composites of dynamic heart models to create a central region with little or no motion or perfusion, surrounded by a region in which the motion and perfusion gradually reverts to normal. To illustrate this methodology, the following gated cardiac acquisitions for different clinical situations were simulated analytically: 1) reduced regional motion and perfusion; 2) same perfusion as in (1) without motion intervention; and 3) washout from the normal and diseased myocardial regions. Both motion and perfusion can change dynamically during a single rotation or multiple rotations of a simulated single-photon emission computed tomography acquisition system.

Hand Motion Classification Using a Multi-Channel Surface Electromyography Sensor

PubMed Central

Tang, Xueyan; Liu, Yunhui; Lv, Congyi; Sun, Dong

2012-01-01

The human hand has multiple degrees of freedom (DOF) for achieving high-dexterity motions. Identifying and replicating human hand motions are necessary to perform precise and delicate operations in many applications, such as haptic applications. Surface electromyography (sEMG) sensors are a low-cost method for identifying hand motions, in addition to the conventional methods that use data gloves and vision detection. The identification of multiple hand motions is challenging because the error rate typically increases significantly with the addition of more hand motions. Thus, the current study proposes two new methods for feature extraction to solve the problem above. The first method is the extraction of the energy ratio features in the time-domain, which are robust and invariant to motion forces and speeds for the same gesture. The second method is the extraction of the concordance correlation features that describe the relationship between every two channels of the multi-channel sEMG sensor system. The concordance correlation features of a multi-channel sEMG sensor system were shown to provide a vast amount of useful information for identification. Furthermore, a new cascaded-structure classifier is also proposed, in which 11 types of hand gestures can be identified accurately using the newly defined features. Experimental results show that the success rate for the identification of the 11 gestures is significantly high. PMID:22438703

Hand motion classification using a multi-channel surface electromyography sensor.

PubMed

Tang, Xueyan; Liu, Yunhui; Lv, Congyi; Sun, Dong

2012-01-01

The human hand has multiple degrees of freedom (DOF) for achieving high-dexterity motions. Identifying and replicating human hand motions are necessary to perform precise and delicate operations in many applications, such as haptic applications. Surface electromyography (sEMG) sensors are a low-cost method for identifying hand motions, in addition to the conventional methods that use data gloves and vision detection. The identification of multiple hand motions is challenging because the error rate typically increases significantly with the addition of more hand motions. Thus, the current study proposes two new methods for feature extraction to solve the problem above. The first method is the extraction of the energy ratio features in the time-domain, which are robust and invariant to motion forces and speeds for the same gesture. The second method is the extraction of the concordance correlation features that describe the relationship between every two channels of the multi-channel sEMG sensor system. The concordance correlation features of a multi-channel sEMG sensor system were shown to provide a vast amount of useful information for identification. Furthermore, a new cascaded-structure classifier is also proposed, in which 11 types of hand gestures can be identified accurately using the newly defined features. Experimental results show that the success rate for the identification of the 11 gestures is significantly high.

Enhanced sampling by multiple molecular dynamics trajectories: carbonmonoxy myoglobin 10 micros A0-->A(1-3) transition from ten 400 picosecond simulations.

PubMed

Loccisano, Anne E; Acevedo, Orlando; DeChancie, Jason; Schulze, Brita G; Evanseck, Jeffrey D

2004-05-01

The utility of multiple trajectories to extend the time scale of molecular dynamics simulations is reported for the spectroscopic A-states of carbonmonoxy myoglobin (MbCO). Experimentally, the A0-->A(1-3) transition has been observed to be 10 micros at 300 K, which is beyond the time scale of standard molecular dynamics simulations. To simulate this transition, 10 short (400 ps) and two longer time (1.2 ns) molecular dynamics trajectories, starting from five different crystallographic and solution phase structures with random initial velocities centered in a 37 A radius sphere of water, have been used to sample the native-fold of MbCO. Analysis of the ensemble of structures gathered over the cumulative 5.6 ns reveals two biomolecular motions involving the side chains of His64 and Arg45 to explain the spectroscopic states of MbCO. The 10 micros A0-->A(1-3) transition involves the motion of His64, where distance between His64 and CO is found to vary up to 8.8 +/- 1.0 A during the transition of His64 from the ligand (A(1-3)) to bulk solvent (A0). The His64 motion occurs within a single trajectory only once, however the multiple trajectories populate the spectroscopic A-states fully. Consequently, multiple independent molecular dynamics simulations have been found to extend biomolecular motion from 5 ns of total simulation to experimental phenomena on the microsecond time scale.

Training value of a fixed-based flight simulator with a dynamic seat

DOT National Transportation Integrated Search

2007-08-20

In this paper, we first explain that pilots experience airplane motion via multiple perceptual systems, which makes motion a candidate for simulation via stimulation of only a subset of these systems. Next, we discuss the relative merit of vestibular...

Measured Correlated Motion of theThree Body Coulomb Interacting System H^+ + H^+ + H^-

NASA Astrophysics Data System (ADS)

Wiese, L. M.

1998-05-01

The problem of three bodies interacting through a 1/r potential is a fundamental problem of physics. While its longstanding fame stems from its application to celestial mechanics, in atomic physics its importance arises from application to Coulomb-interacting systems, in which all three bodies carry some net charge. Because the three bodies interact through long range Coulomb forces over their entire path, their motion can be highly correlated. The effect of the interaction among the three bodies and any resulting correlated motion is reflected in how the available energy is ultimately shared among the three particles. By experimentally determining the energy sharing in a three body system, we can gain insight into the interactions governing the system. For the three body Coulomb interacting system of H^+ + H^+ + H^-, we have measured the partitioning of available center of mass (c.m.) energy among the particles when the system is in a near collinear configuration. By colliding 4 keV H_3^+ with a He target gas cell, we produce the H^+ + H^+ + H^- system a few eV above the dissociative limit. All three fragments are laboratory energy and angle resolved. By detecting all three in triple coincidence, we determine unambiguously the final state dynamics for each triply coincident event. Transforming our results to the c.m. frame, we determine the partitioning of available energy among the three particles. We have modified the Dalitz plot of high energy physics to elucidate correlations in the motion of any three body atomic system. Correlated motion in the H^+ + H^+ + H^- system is indicated by a nonuniform distribution on the Dalitz plot. For the near collinear breakup of H_3^+, we have observed the H^- to reside anywhere between the two H^+, from the Coulomb saddle point to the near vicinity of a proton. This work is supported by NSF Grant Number 9419505.

Conditional spectrum computation incorporating multiple causal earthquakes and ground-motion prediction models

USGS Publications Warehouse

Lin, Ting; Harmsen, Stephen C.; Baker, Jack W.; Luco, Nicolas

2013-01-01

The conditional spectrum (CS) is a target spectrum (with conditional mean and conditional standard deviation) that links seismic hazard information with ground-motion selection for nonlinear dynamic analysis. Probabilistic seismic hazard analysis (PSHA) estimates the ground-motion hazard by incorporating the aleatory uncertainties in all earthquake scenarios and resulting ground motions, as well as the epistemic uncertainties in ground-motion prediction models (GMPMs) and seismic source models. Typical CS calculations to date are produced for a single earthquake scenario using a single GMPM, but more precise use requires consideration of at least multiple causal earthquakes and multiple GMPMs that are often considered in a PSHA computation. This paper presents the mathematics underlying these more precise CS calculations. Despite requiring more effort to compute than approximate calculations using a single causal earthquake and GMPM, the proposed approach produces an exact output that has a theoretical basis. To demonstrate the results of this approach and compare the exact and approximate calculations, several example calculations are performed for real sites in the western United States. The results also provide some insights regarding the circumstances under which approximate results are likely to closely match more exact results. To facilitate these more precise calculations for real applications, the exact CS calculations can now be performed for real sites in the United States using new deaggregation features in the U.S. Geological Survey hazard mapping tools. Details regarding this implementation are discussed in this paper.

Meshless Modeling of Deformable Shapes and their Motion

PubMed Central

Adams, Bart; Ovsjanikov, Maks; Wand, Michael; Seidel, Hans-Peter; Guibas, Leonidas J.

2010-01-01

We present a new framework for interactive shape deformation modeling and key frame interpolation based on a meshless finite element formulation. Starting from a coarse nodal sampling of an object’s volume, we formulate rigidity and volume preservation constraints that are enforced to yield realistic shape deformations at interactive frame rates. Additionally, by specifying key frame poses of the deforming shape and optimizing the nodal displacements while targeting smooth interpolated motion, our algorithm extends to a motion planning framework for deformable objects. This allows reconstructing smooth and plausible deformable shape trajectories in the presence of possibly moving obstacles. The presented results illustrate that our framework can handle complex shapes at interactive rates and hence is a valuable tool for animators to realistically and efficiently model and interpolate deforming 3D shapes. PMID:24839614

Random Matrix Approach to Quantum Adiabatic Evolution Algorithms

NASA Technical Reports Server (NTRS)

Boulatov, Alexei; Smelyanskiy, Vadier N.

2004-01-01

We analyze the power of quantum adiabatic evolution algorithms (Q-QA) for solving random NP-hard optimization problems within a theoretical framework based on the random matrix theory (RMT). We present two types of the driven RMT models. In the first model, the driving Hamiltonian is represented by Brownian motion in the matrix space. We use the Brownian motion model to obtain a description of multiple avoided crossing phenomena. We show that the failure mechanism of the QAA is due to the interaction of the ground state with the "cloud" formed by all the excited states, confirming that in the driven RMT models. the Landau-Zener mechanism of dissipation is not important. We show that the QAEA has a finite probability of success in a certain range of parameters. implying the polynomial complexity of the algorithm. The second model corresponds to the standard QAEA with the problem Hamiltonian taken from the Gaussian Unitary RMT ensemble (GUE). We show that the level dynamics in this model can be mapped onto the dynamics in the Brownian motion model. However, the driven RMT model always leads to the exponential complexity of the algorithm due to the presence of the long-range intertemporal correlations of the eigenvalues. Our results indicate that the weakness of effective transitions is the leading effect that can make the Markovian type QAEA successful.

Spatiotemporal motion boundary detection and motion boundary velocity estimation for tracking moving objects with a moving camera: a level sets PDEs approach with concurrent camera motion compensation.

PubMed

Feghali, Rosario; Mitiche, Amar

2004-11-01

The purpose of this study is to investigate a method of tracking moving objects with a moving camera. This method estimates simultaneously the motion induced by camera movement. The problem is formulated as a Bayesian motion-based partitioning problem in the spatiotemporal domain of the image quence. An energy functional is derived from the Bayesian formulation. The Euler-Lagrange descent equations determine imultaneously an estimate of the image motion field induced by camera motion and an estimate of the spatiotemporal motion undary surface. The Euler-Lagrange equation corresponding to the surface is expressed as a level-set partial differential equation for topology independence and numerically stable implementation. The method can be initialized simply and can track multiple objects with nonsimultaneous motions. Velocities on motion boundaries can be estimated from geometrical properties of the motion boundary. Several examples of experimental verification are given using synthetic and real-image sequences.

Two case reports-Use of relative motion orthoses to manage extensor tendon zones III and IV and sagittal band injuries in adjacent fingers.

PubMed

Hirth, Melissa J; Howell, Julianne W; O'Brien, Lisa

Case report. Injuries to adjacent fingers with differing extensor tendon (ET) zones and/or sagittal band pose a challenge to therapists as no treatment guidelines exist. This report highlights how the relative motion flexion/extension (RMF/RME) concepts were combined into one orthosis to manage a zone IV ET repair (RME) and a zone III central slip repair (RMF) in adjacent fingers (Case 1); and how a single RME orthosis was adapted to limit proximal interphalangeal joint motion to manage multi-level ET zone III-IV injuries and a sagittal band repair in adjacent fingers (case 2). Adapted relative motion orthoses allowed early active motion and graded exercises based on clinical reasoning and evidence. Outcomes were standard TAM% and Miller's criteria. 'Excellent' and 'good' outcomes were achieved by twelve weeks post surgery. Both cases returned to unrestricted work at 6 and 7 weeks. Neither reported functional deficits at discharge. Outcomes in 2 cases involving multiple digit injuries exceeded those previously reported for ET zone III-IV repairs. Relative motion orthoses can be adapted and applied to multi-finger injuries, eliminating the need for multiple, bulky or functionally-limiting orthoses. 4. Copyright © 2017 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

LCC demons with divergence term for liver MRI motion correction

NASA Astrophysics Data System (ADS)

Oh, Jihun; Martin, Diego; Skrinjar, Oskar

2010-03-01

Contrast-enhanced liver MR image sequences acquired at multiple times before and after contrast administration have been shown to be critically important for the diagnosis and monitoring of liver tumors and may be used for the quantification of liver inflammation and fibrosis. However, over multiple acquisitions, the liver moves and deforms due to patient and respiratory motion. In order to analyze contrast agent uptake one first needs to correct for liver motion. In this paper we present a method for the motion correction of dynamic contrastenhanced liver MR images. For this purpose we use a modified version of the Local Correlation Coefficient (LCC) Demons non-rigid registration method. Since the liver is nearly incompressible its displacement field has small divergence. For this reason we add a divergence term to the energy that is minimized in the LCC Demons method. We applied the method to four sequences of contrast-enhanced liver MR images. Each sequence had a pre-contrast scan and seven post-contrast scans. For each post-contrast scan we corrected for the liver motion relative to the pre-contrast scan. Quantitative evaluation showed that the proposed method improved the liver alignment relative to the non-corrected and translation-corrected scans and visual inspection showed no visible misalignment of the motion corrected contrast-enhanced scans and pre-contrast scan.

Many-Body Physics in Long-Range Interacting Quantum Systems

NASA Astrophysics Data System (ADS)

Zhu, Bihui

Ultracold atomic and molecular systems provide a useful platform for understanding quantum many-body physics. Recent progresses in AMO experiments enable access to systems exhibiting long-range interactions, opening a window for exploring the interplay between long-range interactions and dissipation. In this thesis, I develop theoretical approaches to study non-equilibrium dynamics in systems where such interplay is crucial. I first focus on a system of KRb molecules, where dipolar interactions and fast chemical reactions coexist. Using a classical kinetic theory and Monte Carlo methods, I study the evaporative cooling in a quasi-two-dimensional trap, and develop a protocol to reach quantum degeneracy. I also study the case where molecules are loaded into an optical lattice, and show that the strong dissipation induces a quantum Zeno effect, which suppresses the molecule loss. The analysis requires including multiple bands to explain recent experimental measurements, and can be used to determine the molecular filling fraction. I also investigate a system of radiating atoms, which experience long-range elastic and dissipative interactions. I explore the collective behavior of atoms and the role of atomic motion. The model is validated by comparison with a recent light scattering experiment using Sr atoms. I also show that incoherently pumped dipoles can undergo a dynamical phase transition to synchronization, and study its signature in the quantum regime.

The Orion Bullets: New GEMS MCAO images

NASA Astrophysics Data System (ADS)

Ginsburg, Adam; Bally, John; Youngblood, Allison

2013-07-01

The Orion A molecular cloud (OMC1) is the nearest site of massive star formation at a distance of 414 pc. The BN/KL region within it contains signs of a massive explosion triggered 500 years ago by decay of a non- hierarchical multiple system of massive stars. We present observations of the OMC1 core at high spatial resolution (<0.1") in narrow-band [Fe II] 1.64um and H2 S(1) 1-0 2.12um filters. The new data reveal compact (0.1" to 0.5") knots with unique excitation and chemical properties, unveiling new details about the three-dimensional structure of the explosion. Bright H2 emission from these compact, high proper-motion knots and compact [Fe II] features are consistent with scenario proposed by Bally et al. (2011) in which they are interpreted to be high density (n > 10^8 cm^{-3}) disk fragments launched from within a few AU of a massive star by a > three-body dynamical interaction that led to the ejection of the BN objects and the formation of a compact (separation < few AU) binary, most likely radio source I. The proper motions are as high as 400 km/s, hinting at the enormous energy unleashed in the explosion. The data also unveiled a population of obscured close binary systems. This new population will allow a comparison of embedded young binary systems with the older, un-obscured, visual binary population to test models of the evolution of multiplicity statistics in the Orion Nebula Cluster.

The Voronoi Implicit Interface Method for computing multiphase physics

PubMed Central

Saye, Robert I.; Sethian, James A.

2011-01-01

We introduce a numerical framework, the Voronoi Implicit Interface Method for tracking multiple interacting and evolving regions (phases) whose motion is determined by complex physics (fluids, mechanics, elasticity, etc.), intricate jump conditions, internal constraints, and boundary conditions. The method works in two and three dimensions, handles tens of thousands of interfaces and separate phases, and easily and automatically handles multiple junctions, triple points, and quadruple points in two dimensions, as well as triple lines, etc., in higher dimensions. Topological changes occur naturally, with no surgery required. The method is first-order accurate at junction points/lines, and of arbitrarily high-order accuracy away from such degeneracies. The method uses a single function to describe all phases simultaneously, represented on a fixed Eulerian mesh. We test the method’s accuracy through convergence tests, and demonstrate its applications to geometric flows, accurate prediction of von Neumann’s law for multiphase curvature flow, and robustness under complex fluid flow with surface tension and large shearing forces. PMID:22106269

A swarm of autonomous miniature underwater robot drifters for exploring submesoscale ocean dynamics.

PubMed

Jaffe, Jules S; Franks, Peter J S; Roberts, Paul L D; Mirza, Diba; Schurgers, Curt; Kastner, Ryan; Boch, Adrien

2017-01-24

Measuring the ever-changing 3-dimensional (3D) motions of the ocean requires simultaneous sampling at multiple locations. In particular, sampling the complex, nonlinear dynamics associated with submesoscales (<1-10 km) requires new technologies and approaches. Here we introduce the Mini-Autonomous Underwater Explorer (M-AUE), deployed as a swarm of 16 independent vehicles whose 3D trajectories are measured near-continuously, underwater. As the vehicles drift with the ambient flow or execute preprogrammed vertical behaviours, the simultaneous measurements at multiple, known locations resolve the details of the flow within the swarm. We describe the design, construction, control and underwater navigation of the M-AUE. A field programme in the coastal ocean using a swarm of these robots programmed with a depth-holding behaviour provides a unique test of a physical-biological interaction leading to plankton patch formation in internal waves. The performance of the M-AUE vehicles illustrates their novel capability for measuring submesoscale dynamics.

The Voronoi Implicit Interface Method for computing multiphase physics.

PubMed

Saye, Robert I; Sethian, James A

2011-12-06

We introduce a numerical framework, the Voronoi Implicit Interface Method for tracking multiple interacting and evolving regions (phases) whose motion is determined by complex physics (fluids, mechanics, elasticity, etc.), intricate jump conditions, internal constraints, and boundary conditions. The method works in two and three dimensions, handles tens of thousands of interfaces and separate phases, and easily and automatically handles multiple junctions, triple points, and quadruple points in two dimensions, as well as triple lines, etc., in higher dimensions. Topological changes occur naturally, with no surgery required. The method is first-order accurate at junction points/lines, and of arbitrarily high-order accuracy away from such degeneracies. The method uses a single function to describe all phases simultaneously, represented on a fixed Eulerian mesh. We test the method's accuracy through convergence tests, and demonstrate its applications to geometric flows, accurate prediction of von Neumann's law for multiphase curvature flow, and robustness under complex fluid flow with surface tension and large shearing forces.

The Voronoi Implicit Interface Method for computing multiphase physics

DOE PAGES

Saye, Robert I.; Sethian, James A.

2011-11-21

In this paper, we introduce a numerical framework, the Voronoi Implicit Interface Method for tracking multiple interacting and evolving regions (phases) whose motion is determined by complex physics (fluids, mechanics, elasticity, etc.), intricate jump conditions, internal constraints, and boundary conditions. The method works in two and three dimensions, handles tens of thousands of interfaces and separate phases, and easily and automatically handles multiple junctions, triple points, and quadruple points in two dimensions, as well as triple lines, etc., in higher dimensions. Topological changes occur naturally, with no surgery required. The method is first-order accurate at junction points/lines, and of arbitrarilymore » high-order accuracy away from such degeneracies. The method uses a single function to describe all phases simultaneously, represented on a fixed Eulerian mesh. Finally, we test the method’s accuracy through convergence tests, and demonstrate its applications to geometric flows, accurate prediction of von Neumann’s law for multiphase curvature flow, and robustness under complex fluid flow with surface tension and large shearing forces.« less

Challenges and solutions for studying collective animal behaviour in the wild.

PubMed

Hughey, Lacey F; Hein, Andrew M; Strandburg-Peshkin, Ariana; Jensen, Frants H

2018-05-19

Mobile animal groups provide some of the most compelling examples of self-organization in the natural world. While field observations of songbird flocks wheeling in the sky or anchovy schools fleeing from predators have inspired considerable interest in the mechanics of collective motion, the challenge of simultaneously monitoring multiple animals in the field has historically limited our capacity to study collective behaviour of wild animal groups with precision. However, recent technological advancements now present exciting opportunities to overcome many of these limitations. Here we review existing methods used to collect data on the movements and interactions of multiple animals in a natural setting. We then survey emerging technologies that are poised to revolutionize the study of collective animal behaviour by extending the spatial and temporal scales of inquiry, increasing data volume and quality, and expediting the post-processing of raw data.This article is part of the theme issue 'Collective movement ecology'. © 2018 The Author(s).

A swarm of autonomous miniature underwater robot drifters for exploring submesoscale ocean dynamics

NASA Astrophysics Data System (ADS)

Jaffe, Jules S.; Franks, Peter J. S.; Roberts, Paul L. D.; Mirza, Diba; Schurgers, Curt; Kastner, Ryan; Boch, Adrien

2017-01-01

Measuring the ever-changing 3-dimensional (3D) motions of the ocean requires simultaneous sampling at multiple locations. In particular, sampling the complex, nonlinear dynamics associated with submesoscales (<1-10 km) requires new technologies and approaches. Here we introduce the Mini-Autonomous Underwater Explorer (M-AUE), deployed as a swarm of 16 independent vehicles whose 3D trajectories are measured near-continuously, underwater. As the vehicles drift with the ambient flow or execute preprogrammed vertical behaviours, the simultaneous measurements at multiple, known locations resolve the details of the flow within the swarm. We describe the design, construction, control and underwater navigation of the M-AUE. A field programme in the coastal ocean using a swarm of these robots programmed with a depth-holding behaviour provides a unique test of a physical-biological interaction leading to plankton patch formation in internal waves. The performance of the M-AUE vehicles illustrates their novel capability for measuring submesoscale dynamics.

Multiple molecular dynamics simulations of human LOX-1 and Trp150Ala mutant reveal the structural determinants causing the full deactivation of the receptor.

PubMed

Iacovelli, Federico; Tucci, Fabio Giovanni; Macari, Gabriele; Falconi, Mattia

2017-10-01

Multiple classical molecular dynamics simulations have been applied to the human LOX-1 receptor to clarify the role of the Trp150Ala mutation in the loss of binding activity. Results indicate that the substitution of this crucial residue, located at the dimer interface, markedly disrupts the wild-type receptor dynamics. The mutation causes an irreversible rearrangement of the subunits interaction pattern that in the wild-type protein allows the maintaining of a specific symmetrical motion of the monomers. The subunits dislocation determines a loss of linearity of the arginines residues composing the basic spine and a consequent alteration of the long-range electrostatic attraction of the substrate. Moreover, the anomalous subunits arrangement observed in the mutated receptor also affects the integrity of the hydrophobic tunnel, actively involved in the short-range hydrophobic recognition of the substrate. The combined effect of these structural rearrangements generates the impairing of the receptor function. © 2017 Wiley Periodicals, Inc.

Improved electromechanical master-slave manipulator

NASA Technical Reports Server (NTRS)

Forster, G.; Goertz, R.; Grimson, J.; Mingesz, D.; Potts, C.

1968-01-01

Electric master-slave manipulator uses force multiplication and allows the operator to remotely control the slave arm. Both the master and slave arms execute seven distinct motions by a specially designed force-reflecting servo having a one to one correspondence between the motion at the master and slave.

Rotating Wavepackets

ERIC Educational Resources Information Center

Lekner, John

2008-01-01

Any free-particle wavepacket solution of Schrodinger's equation can be converted by differentiations to wavepackets rotating about the original direction of motion. The angular momentum component along the motion associated with this rotation is an integral multiple of [h-bar]. It is an "intrinsic" angular momentum: independent of origin and…

Visual Search for Motion-Form Conjunctions: Selective Attention to Movement Direction.

PubMed

Von Mühlenen, Adrian; Müller, Hermann J

1999-07-01

In 2 experiments requiring visual search for conjunctions of motion and form, the authors reinvestigated whether motion-based filtering (e.g., P. McLeod, J. Driver, Z. Dienes, & J. Crisp, 1991) is direction selective and whether cuing of the target direction promotes efficient search performance. In both experiments, the authors varied the number of movement directions in the display and the predictability of the target direction. Search was less efficient when items moved in multiple (2, 3, and 4) directions as compared with just 1 direction. Furthermore, precuing of the target direction facilitated the search, even with "wrap-around" displays, relatively more when items moved in multiple directions. The authors proposed 2 principles to explain that pattern of effects: (a) interference on direction computation between items moving in different directions (e.g., N. Qian & R. A. Andersen, 1994) and (b) selective direction tuning of motion detectors involving a receptive-field contraction (cf. J. Moran & R. Desimone, 1985; S. Treue & J. H. R. Maunsell, 1996).

Motion-free hybrid design laser beam propagation analyzer using a digital micromirror device and a variable focus liquid lens.

PubMed

Sheikh, Mumtaz; Riza, Nabeel A

2010-06-01

To the best of our knowledge, we propose the first motion-free laser beam propagation analyzer with a hybrid design using a digital micromirror device (DMD) and a liquid electronically controlled variable focus lens (ECVFL). Unlike prior analyzers that require profiling the beam at multiple locations along the light propagation axis, the proposed analyzer profiles the beam at the same plane for multiple values of the ECVFL focal length, thus eliminating beam profiler assembly motion. In addition to measuring standard Gaussian beam parameters, the analyzer can also be used to measure the M(2) beam propagation parameter of a multimode beam. Proof-of-concept beam parameter measurements with the proposed analyzer are successfully conducted for a 633 nm laser beam. Given the all-digital nature of the DMD-based profiling and all-analog motion-free nature of the ECVFL beam focus control, the proposed analyzer versus prior art promises better repeatability, speed, and reliability.

Grouping and trajectory storage in multiple object tracking: impairments due to common item motions.

PubMed

Suganuma, Mutsumi; Yokosawa, Kazuhiko

2006-01-01

In our natural viewing, we notice that objects change their locations across space and time. However, there has been relatively little consideration of the role of motion information in the construction and maintenance of object representations. We investigated this question in the context of the multiple object tracking (MOT) paradigm, wherein observers must keep track of target objects as they move randomly amid featurally identical distractors. In three experiments, we observed impairments in tracking ability when the motions of the target and distractor items shared particular properties. Specifically, we observed impairments when the target and distractor items were in a chasing relationship or moved in a uniform direction. Surprisingly, tracking ability was impaired by these manipulations even when observers failed to notice them. Our results suggest that differentiable trajectory information is an important factor in successful performance of MOT tasks. More generally, these results suggest that various types of common motion can serve as cues to form more global object representations even in the absence of other grouping cues.

Correlation-based motion vector processing with adaptive interpolation scheme for motion-compensated frame interpolation.

PubMed

Huang, Ai-Mei; Nguyen, Truong

2009-04-01

In this paper, we address the problems of unreliable motion vectors that cause visual artifacts but cannot be detected by high residual energy or bidirectional prediction difference in motion-compensated frame interpolation. A correlation-based motion vector processing method is proposed to detect and correct those unreliable motion vectors by explicitly considering motion vector correlation in the motion vector reliability classification, motion vector correction, and frame interpolation stages. Since our method gradually corrects unreliable motion vectors based on their reliability, we can effectively discover the areas where no motion is reliable to be used, such as occlusions and deformed structures. We also propose an adaptive frame interpolation scheme for the occlusion areas based on the analysis of their surrounding motion distribution. As a result, the interpolated frames using the proposed scheme have clearer structure edges and ghost artifacts are also greatly reduced. Experimental results show that our interpolated results have better visual quality than other methods. In addition, the proposed scheme is robust even for those video sequences that contain multiple and fast motions.

Human comfort response to random motions with a dominant pitching motion

NASA Technical Reports Server (NTRS)

Stone, R. W., Jr.

1980-01-01

The effects of random pitching velocities on passenger ride comfort response were examined on the NASA Langley Visual Motion Simulator. The effects of power spectral density shape and frequency ranges from 0 to 2 Hz were studied. The subjective rating data and the physical motion data obtained are presented. No attempt at interpretation or detailed analysis of the data is made. Motions in all degrees of freedom existed as well as the intended pitching motion, because of the characteristics of the simulator. These unwanted motions may have introduced some interactive effects on passenger responses which should be considered in any analysis of the data.

Canal–Otolith Interactions and Detection Thresholds of Linear and Angular Components During Curved-Path Self-Motion

PubMed Central

MacNeilage, Paul R.; Turner, Amanda H.

2010-01-01

Gravitational signals arising from the otolith organs and vertical plane rotational signals arising from the semicircular canals interact extensively for accurate estimation of tilt and inertial acceleration. Here we used a classical signal detection paradigm to examine perceptual interactions between otolith and horizontal semicircular canal signals during simultaneous rotation and translation on a curved path. In a rotation detection experiment, blindfolded subjects were asked to detect the presence of angular motion in blocks where half of the trials were pure nasooccipital translation and half were simultaneous translation and yaw rotation (curved-path motion). In separate, translation detection experiments, subjects were also asked to detect either the presence or the absence of nasooccipital linear motion in blocks, in which half of the trials were pure yaw rotation and half were curved path. Rotation thresholds increased slightly, but not significantly, with concurrent linear velocity magnitude. Yaw rotation detection threshold, averaged across all conditions, was 1.45 ± 0.81°/s (3.49 ± 1.95°/s2). Translation thresholds, on the other hand, increased significantly with increasing magnitude of concurrent angular velocity. Absolute nasooccipital translation detection threshold, averaged across all conditions, was 2.93 ± 2.10 cm/s (7.07 ± 5.05 cm/s2). These findings suggest that conscious perception might not have independent access to separate estimates of linear and angular movement parameters during curved-path motion. Estimates of linear (and perhaps angular) components might instead rely on integrated information from canals and otoliths. Such interaction may underlie previously reported perceptual errors during curved-path motion and may originate from mechanisms that are specialized for tilt-translation processing during vertical plane rotation. PMID:20554843

Explanation of relativistic phenomena on the basis of interactions of particle energy, applied energy, and field energy

NASA Astrophysics Data System (ADS)

Fernando, Viraj

2011-09-01

This paper formulates a coherent theory of occurrence of relativistic phenomena in their interconnection in a feedback loop, unlike other theories, by tracing back concepts that Newton held but suppressed, when he developed his mechanics in his Principia. Despite Newtonian mechanics being based on a closed system, Newton in the General Scholium has indicated that in reality thee is in an open system, where 'a certain most subtle spirit' participates and directs all interactions from motion of bodies, to motion of light, to how the human brain operates. We have identified this 'most subtle spirit' as the non-empirical 'universal governing field' and that no empirical interaction in this universe can occur without exchange of energy between the empirical interactants and the governing field. By analyzing the energy momentum equation, we have demonstrated that everything empirical has a non-empirical substratum, identified with Spinoza's primitive substance, which binds everything in the universe to the field and through it to one another. Algorithm of Motion is founded on the Pythagorean character of the energy-momentum equation, which is applicable to all velocities 0

The Experience of Force: The Role of Haptic Experience of Forces in Visual Perception of Object Motion and Interactions, Mental Simulation, and Motion-Related Judgments

ERIC Educational Resources Information Center

White, Peter A.

2012-01-01

Forces are experienced in actions on objects. The mechanoreceptor system is stimulated by proximal forces in interactions with objects, and experiences of force occur in a context of information yielded by other sensory modalities, principally vision. These experiences are registered and stored as episodic traces in the brain. These stored…

A novel multiple description scalable coding scheme for mobile wireless video transmission

NASA Astrophysics Data System (ADS)

Zheng, Haifeng; Yu, Lun; Chen, Chang Wen

2005-03-01

We proposed in this paper a novel multiple description scalable coding (MDSC) scheme based on in-band motion compensation temporal filtering (IBMCTF) technique in order to achieve high video coding performance and robust video transmission. The input video sequence is first split into equal-sized groups of frames (GOFs). Within a GOF, each frame is hierarchically decomposed by discrete wavelet transform. Since there is a direct relationship between wavelet coefficients and what they represent in the image content after wavelet decomposition, we are able to reorganize the spatial orientation trees to generate multiple bit-streams and employed SPIHT algorithm to achieve high coding efficiency. We have shown that multiple bit-stream transmission is very effective in combating error propagation in both Internet video streaming and mobile wireless video. Furthermore, we adopt the IBMCTF scheme to remove the redundancy for inter-frames along the temporal direction using motion compensated temporal filtering, thus high coding performance and flexible scalability can be provided in this scheme. In order to make compressed video resilient to channel error and to guarantee robust video transmission over mobile wireless channels, we add redundancy to each bit-stream and apply error concealment strategy for lost motion vectors. Unlike traditional multiple description schemes, the integration of these techniques enable us to generate more than two bit-streams that may be more appropriate for multiple antenna transmission of compressed video. Simulate results on standard video sequences have shown that the proposed scheme provides flexible tradeoff between coding efficiency and error resilience.

Dynamical Evolution and Spin-Orbit Resonances of Potentially Habitable Exoplanets: The Case of GJ 581d

NASA Astrophysics Data System (ADS)

Makarov, Valeri V.; Berghea, Ciprian; Efroimsky, Michael

2012-12-01

GJ 581d is a potentially habitable super-Earth in the multiple system of exoplanets orbiting a nearby M dwarf. We investigate this planet's long-term dynamics with an emphasis on its probable final rotation states acquired via tidal interaction with the host. The published radial velocities for the star are re-analyzed with a benchmark planet detection algorithm to confirm that there is no evidence for the recently proposed two additional planets (f and g). Limiting the scope to the four originally detected planets, we assess the dynamical stability of the system and find bounded chaos in the orbital motion. For the planet d, the characteristic Lyapunov time is 38 yr. Long-term numerical integration reveals that the system of four planets is stable, with the eccentricity of the planet d changing quasi-periodically in a tight range around 0.27, and with its semimajor axis varying only a little. The spin-orbit interaction of GJ 581d with its host star is dominated by the tides exerted by the star on the planet. We model this interaction, assuming a terrestrial composition of the mantle. Besides the triaxiality-caused torque and the secular part of the tidal torque, which are conventionally included in the equation of motion, we also include the tidal torques' oscillating components. It turns out that, depending on the mantle temperature, the planet gets trapped into the 2:1 or an even higher spin-orbit resonance. It is very improbable that the planet could have reached the 1:1 resonance. This improves the possibility of the planet being suitable for sustained life.

Suggested Courseware for the Non-Calculus Physics Student: Projectile Motion, Circular Motion, Rotational Dynamics, and Statics.

ERIC Educational Resources Information Center

Mahoney, Joyce; And Others

1988-01-01

Evaluates 10 courseware packages covering topics for introductory physics. Discusses the price; sub-topics; program type; interaction; possible hardware; time; calculus required; graphics; and comments on each program. Recommends two packages in projectile and circular motion, and three packages in statics and rotational dynamics. (YP)

Meaning Making with Motion Is Messy: Developing a STEM Learning Community

ERIC Educational Resources Information Center

LópezLeiva, Carlos; Roberts-Harris, Deborah; von Toll, Elizabeth

2016-01-01

Through a collaborative effort between a sixth-grade teacher and two university faculty, we designed an integrated unit to learn about motion and we learned that an integrated teaching and learning experience about motion is MESSY (i.e., it includes movement, engagement, social interactions, spontaneity, yikes, and yippees!). We engaged in a…

Cervical motion testing: methodology and clinical implications.

PubMed

Prushansky, Tamara; Dvir, Zeevi

2008-09-01

Measurement of cervical motion (CM) is probably the most commonly applied functional outcome measure in assessing the status of patients with cervical pathology. In general terms, CM refers to motion of the head relative to the trunk as well as conjunct motions within the cervical spine. Multiple techniques and instruments have been used for assessing CM. These were associated with a wide variety of parameters relating to accuracy, reproducibility, and validity. Modern measurement systems enable recording, processing, and documentation of CM with a high degree of precision. Cervical motion measures provide substantial information regarding the severity of motion limitation and level of effort in cervically involved patients. They may also be used for following up performance during and after conservative or invasive interventions.

Shape matters: Near-field fluid mechanics dominate the collective motions of ellipsoidal squirmers.

PubMed

Kyoya, K; Matsunaga, D; Imai, Y; Omori, T; Ishikawa, T

2015-12-01

Microswimmers show a variety of collective motions. Despite extensive study, questions remain regarding the role of near-field fluid mechanics in collective motion. In this paper, we describe precisely the Stokes flow around hydrodynamically interacting ellipsoidal squirmers in a monolayer suspension. The results showed that various collective motions, such as ordering, aggregation, and whirls, are dominated by the swimming mode and the aspect ratio. The collective motions are mainly induced by near-field fluid mechanics, despite Stokes flow propagation over a long range. These results emphasize the importance of particle shape in collective motion.

Motion Correction in PROPELLER and Turboprop-MRI

PubMed Central

Tamhane, Ashish A.; Arfanakis, Konstantinos

2009-01-01

PROPELLER and Turboprop-MRI are characterized by greatly reduced sensitivity to motion, compared to their predecessors, fast spin-echo and gradient and spin-echo, respectively. This is due to the inherent self-navigation and motion correction of PROPELLER-based techniques. However, it is unknown how various acquisition parameters that determine k-space sampling affect the accuracy of motion correction in PROPELLER and Turboprop-MRI. The goal of this work was to evaluate the accuracy of motion correction in both techniques, to identify an optimal rotation correction approach, and determine acquisition strategies for optimal motion correction. It was demonstrated that, blades with multiple lines allow more accurate estimation of motion than blades with fewer lines. Also, it was shown that Turboprop-MRI is less sensitive to motion than PROPELLER. Furthermore, it was demonstrated that the number of blades does not significantly affect motion correction. Finally, clinically appropriate acquisition strategies that optimize motion correction were discussed for PROPELLER and Turboprop-MRI. PMID:19365858

Stereoscopic advantages for vection induced by radial, circular, and spiral optic flows.

PubMed

Palmisano, Stephen; Summersby, Stephanie; Davies, Rodney G; Kim, Juno

2016-11-01

Although observer motions project different patterns of optic flow to our left and right eyes, there has been surprisingly little research into potential stereoscopic contributions to self-motion perception. This study investigated whether visually induced illusory self-motion (i.e., vection) is influenced by the addition of consistent stereoscopic information to radial, circular, and spiral (i.e., combined radial + circular) patterns of optic flow. Stereoscopic vection advantages were found for radial and spiral (but not circular) flows when monocular motion signals were strong. Under these conditions, stereoscopic benefits were greater for spiral flow than for radial flow. These effects can be explained by differences in the motion aftereffects generated by these displays, which suggest that the circular motion component in spiral flow selectively reduced adaptation to stereoscopic motion-in-depth. Stereoscopic vection advantages were not observed for circular flow when monocular motion signals were strong, but emerged when monocular motion signals were weakened. These findings show that stereoscopic information can contribute to visual self-motion perception in multiple ways.

77 FR 72387 - Jeffery J. Becker, D.D.S., and Jeffery J. Becker, D.D.S., Affordable Care Decision and Order

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-05

....' '' Order Regarding Respondent's Multiple Motions For Appropriate Relief (ALJ Ex. 25), at 10 (quoting Forest... silent on the requirements of a registrant under 21 CFR 1307.21.'' Gov. Resp. to Respondent's Motion to...

SMART USE OF COMPUTER-AIDED SPERM ANALYSIS (CASA) TO CHARACTERIZE SPERM MOTION

EPA Science Inventory

Computer-aided sperm analysis (CASA) has evolved over the past fifteen years to provide an objective, practical means of measuring and characterizing the velocity and parttern of sperm motion. CASA instruments use video frame-grabber boards to capture multiple images of spermato...

The Kardar-Parisi-Zhang Equation as Scaling Limit of Weakly Asymmetric Interacting Brownian Motions

NASA Astrophysics Data System (ADS)

Diehl, Joscha; Gubinelli, Massimiliano; Perkowski, Nicolas

2017-09-01

We consider a system of infinitely many interacting Brownian motions that models the height of a one-dimensional interface between two bulk phases. We prove that the large scale fluctuations of the system are well approximated by the solution to the KPZ equation provided the microscopic interaction is weakly asymmetric. The proof is based on the martingale solutions of Gonçalves and Jara (Arch Ration Mech Anal 212(2):597-644, 2014) and the corresponding uniqueness result of Gubinelli and Perkowski (Energy solutions of KPZ are unique, 2015).

Observability/Identifiability of Rigid Motion under Perspective Projection

DTIC Science & Technology

1994-03-08

Faugeras and S. Maybank . Motion from point mathces: multiplicity of solutions. Int. J, of Computer Vision, 1990. [16] D.B. Gennery. Tracking known...sequences. Int. 9. of computer vision, 1989. [37] S. Maybank . Theory of reconstruction from image motion. Springer Verlag, 1992. [38] Andrea 6...defined in section 5; in this appendix we show a simple characterization which is due to Faugeras and Maybank [15, 371. Theorem B.l . Let Q = UCVT

Flexibility Versus Expertise: A Closer Look at the Employment of United States Air Force Imagery Analysts

DTIC Science & Technology

2017-10-01

significant pressure upon Air Force imagery analysts to exhibit expertise in multiple disciplines including full-motion video , electro-optical still...disciplines varies, but the greatest divergence is between full-motion video and all other forms of still imagery. This paper delves into three...motion video discipline were to be created. The research reveals several positive aspects of this course of action but precautions would be required

Folded Elastic Strip-Based Triboelectric Nanogenerator for Harvesting Human Motion Energy for Multiple Applications.

PubMed

Kang, Yue; Wang, Bo; Dai, Shuge; Liu, Guanlin; Pu, Yanping; Hu, Chenguo

2015-09-16

A folded elastic strip-based triboelectric nanogenerator (FS-TENG) made from two folded double-layer elastic strips of Al/PET and PTFE/PET can achieve multiple functions by low frequency mechanical motion. A single FS-TENG with strip width of 3 cm and length of 27 cm can generate a maximum output current, open-circuit voltage, and peak power of 55 μA, 840 V, and 7.33 mW at deformation frequency of 4 Hz with amplitude of 2.5 cm, respectively. This FS-TENG can work as a weight sensor due to its good elasticity. An integrated generator assembled by four FS-TENGs (IFS-TENG) can harvest the energy of human motion like flapping hands and walking steps. In addition, the IFS-TENG combined with electromagnetically induced electricity can achieve a completely self-driven doorbell with flashing lights. Moreover, a box-like generator integrated by four IFS-TENGs inside can work in horizontal or random motion modes and can be improved to harvest energy in all directions. This work promotes the research of completely self-driven systems and energy harvesting of human motion for applications in our daily life.

Predicting 2D target velocity cannot help 2D motion integration for smooth pursuit initiation.

PubMed

Montagnini, Anna; Spering, Miriam; Masson, Guillaume S

2006-12-01

Smooth pursuit eye movements reflect the temporal dynamics of bidimensional (2D) visual motion integration. When tracking a single, tilted line, initial pursuit direction is biased toward unidimensional (1D) edge motion signals, which are orthogonal to the line orientation. Over 200 ms, tracking direction is slowly corrected to finally match the 2D object motion during steady-state pursuit. We now show that repetition of line orientation and/or motion direction does not eliminate the transient tracking direction error nor change the time course of pursuit correction. Nonetheless, multiple successive presentations of a single orientation/direction condition elicit robust anticipatory pursuit eye movements that always go in the 2D object motion direction not the 1D edge motion direction. These results demonstrate that predictive signals about target motion cannot be used for an efficient integration of ambiguous velocity signals at pursuit initiation.

Solving Fluid Structure Interaction Problems with an Immersed Boundary Method

NASA Technical Reports Server (NTRS)

Barad, Michael F.; Brehm, Christoph; Kiris, Cetin C.

2016-01-01

An immersed boundary method for the compressible Navier-Stokes equations can be used for moving boundary problems as well as fully coupled fluid-structure interaction is presented. The underlying Cartesian immersed boundary method of the Launch Ascent and Vehicle Aerodynamics (LAVA) framework, based on the locally stabilized immersed boundary method previously presented by the authors, is extended to account for unsteady boundary motion and coupled to linear and geometrically nonlinear structural finite element solvers. The approach is validated for moving boundary problems with prescribed body motion and fully coupled fluid structure interaction problems. Keywords: Immersed Boundary Method, Higher-Order Finite Difference Method, Fluid Structure Interaction.

Quantized vortices in arbitrary dimensions and the normal-to-superfluid phase transition

NASA Astrophysics Data System (ADS)

Bora, Florin

The structure and energetics of superflow around quantized vortices, and the motion inherited by these vortices from this superflow, are explored in the general setting of a superfluid in arbitrary dimensions. The vortices may be idealized as objects of co-dimension two, such as one-dimensional loops and two-dimensional closed surfaces, respectively, in the cases of three- and four-dimensional superfluidity. By using the analogy between vortical superflow and Ampere-Maxwell magnetostatics, the equilibrium superflow containing any specified collection of vortices is constructed. The energy of the superflow is found to take on a simple form for vortices that are smooth and asymptotically large, compared with the vortex core size. The motion of vortices is analyzed in general, as well as for the special cases of hyper-spherical and weakly distorted hyper-planar vortices. In all dimensions, vortex motion reflects vortex geometry. In dimension four and higher, this includes not only extrinsic but also intrinsic aspects of the vortex shape, which enter via the first and second fundamental forms of classical geometry. For hyper-spherical vortices, which generalize the vortex rings of three dimensional superfluidity, the energy-momentum relation is determined. Simple scaling arguments recover the essential features of these results, up to numerical and logarithmic factors. Extending these results to systems containing multiple vortices is elementary due to the linearity of the theory. The energy for multiple vortices is thus a sum of self-energies and power-law interaction terms. The statistical mechanics of a system containing vortices is addressed via the grand canonical partition function. A renormalization-group analysis in which the low energy excitations are integrated approximately, is used to compute certain critical coefficients. The exponents obtained via this approximate procedure are compared with values obtained previously by other means. For dimensions higher than three the superfluid density is found to vanish as the critical temperature is approached from below.

Inertial Measures of Motion for Clinical Biomechanics: Comparative Assessment of Accuracy under Controlled Conditions - Effect of Velocity

PubMed Central

Lebel, Karina; Boissy, Patrick; Hamel, Mathieu; Duval, Christian

2013-01-01

Background Inertial measurement of motion with Attitude and Heading Reference Systems (AHRS) is emerging as an alternative to 3D motion capture systems in biomechanics. The objectives of this study are: 1) to describe the absolute and relative accuracy of multiple units of commercially available AHRS under various types of motion; and 2) to evaluate the effect of motion velocity on the accuracy of these measurements. Methods The criterion validity of accuracy was established under controlled conditions using an instrumented Gimbal table. AHRS modules were carefully attached to the center plate of the Gimbal table and put through experimental static and dynamic conditions. Static and absolute accuracy was assessed by comparing the AHRS orientation measurement to those obtained using an optical gold standard. Relative accuracy was assessed by measuring the variation in relative orientation between modules during trials. Findings Evaluated AHRS systems demonstrated good absolute static accuracy (mean error < 0.5o) and clinically acceptable absolute accuracy under condition of slow motions (mean error between 0.5o and 3.1o). In slow motions, relative accuracy varied from 2o to 7o depending on the type of AHRS and the type of rotation. Absolute and relative accuracy were significantly affected (p<0.05) by velocity during sustained motions. The extent of that effect varied across AHRS. Interpretation Absolute and relative accuracy of AHRS are affected by environmental magnetic perturbations and conditions of motions. Relative accuracy of AHRS is mostly affected by the ability of all modules to locate the same global reference coordinate system at all time. Conclusions Existing AHRS systems can be considered for use in clinical biomechanics under constrained conditions of use. While their individual capacity to track absolute motion is relatively consistent, the use of multiple AHRS modules to compute relative motion between rigid bodies needs to be optimized according to the conditions of operation. PMID:24260324

SU-E-J-57: First Development of Adapting to Intrafraction Relative Motion Between Prostate and Pelvic Lymph Nodes Targets

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

Ge, Y; Colvill, E; O’Brien, R

2015-06-15

Purpose Large intrafraction relative motion of multiple targets is common in advanced head and neck, lung, abdominal, gynaecological and urological cancer, jeopardizing the treatment outcomes. The objective of this study is to develop a real-time adaptation strategy, for the first time, to accurately correct for the relative motion of multiple targets by reshaping the treatment field using the multi-leaf collimator (MLC). Methods The principle of tracking the simultaneously treated but differentially moving tumor targets is to determine the new aperture shape that conforms to the shifted targets. Three dimensional volumes representing the individual targets are projected to the beam’s eyemore » view. The leaf openings falling inside each 2D projection will be shifted according to the measured motion of each target to form the new aperture shape. Based on the updated beam shape, new leaf positions will be determined with optimized trade-off between the target underdose and healthy tissue overdose, and considerations of the physical constraints of the MLC. Taking a prostate cancer patient with pelvic lymph node involvement as an example, a preliminary dosimetric study was conducted to demonstrate the potential treatment improvement compared to the state-of- art adaptation technique which shifts the whole beam to track only one target. Results The world-first intrafraction adaptation system capable of reshaping the beam to correct for the relative motion of multiple targets has been developed. The dose in the static nodes and small bowel are closer to the planned distribution and the V45 of small bowel is decreased from 110cc to 75cc, corresponding to a 30% reduction by this technique compared to the state-of-art adaptation technique. Conclusion The developed adaptation system to correct for intrafraction relative motion of multiple targets will guarantee the tumour coverage and thus enable PTV margin reduction to minimize the high target dose to the adjacent organs-at-risk. The authors acknowledge funding support from the Australian NHMRC Australia Fellowship and NHMRC Project Grant No. APP1042375.« less

Hydrodynamic interactions for complex-shaped nanocarriers in targeted drug delivery

NASA Astrophysics Data System (ADS)

Wang, Yaohong; Eckmann, David; Radhakrishnan, Ravi; Ayyaswamy, Portonovo

2014-11-01

Nanocarrier motion in a blood vessel involves hydrodynamic and Brownian interactions, which collectively dictate the efficacy in targeted drug delivery. The shape of nanocarriers plays a crucial role in drug delivery. In order to quantify the flow and association properties of elliptical nanoparticles, we have developed an arbitrary Lagrangian-Eulerian framework with capabilities to simulate the hydrodynamic motion of nanoparticles of arbitrary shapes. We introduce the quaternions for rotational motion, and two collision models, namely, (a) an impulse-based model for wall-particle collision, and (b) the short-range repulsive Gay-Berne potential for particle-particle collision. We also study the red blood cell and nanocarrier (such as ellipsoid) interactions. We compare our results with those obtained for a hard sphere model for both RBCs and nanocarriers. Supported by NIH through grant U01-EB016027.

Quantized orbits in weakly coupled Belousov-Zhabotinsky reactors

NASA Astrophysics Data System (ADS)

Weiss, S.; Deegan, R. D.

2015-06-01

Using numerical and experimental tools, we study the motion of two coupled spiral cores in a light-sensitive variant of the Belousov-Zhabotinsky reaction. Each core resides on a separate two-dimensional domain, and is coupled to the other by light. When both spirals have the same sense of rotation, the cores are attracted to a circular trajectory with a diameter quantized in integer units of the spiral wavelength λ. When the spirals have opposite senses of rotation, the cores are attracted towards different but parallel straight trajectories, separated by an integer multiple of λ/2. We present a model that explains this behavior as the result of a spiral wavefront-core interaction that produces a deterministic displacement of the core and a retardation of its phase.

Recovery of Background Structures in Nanoscale Helium Ion Microscope Imaging.

PubMed

Carasso, Alfred S; Vladár, András E

2014-01-01

This paper discusses a two step enhancement technique applicable to noisy Helium Ion Microscope images in which background structures are not easily discernible due to a weak signal. The method is based on a preliminary adaptive histogram equalization, followed by 'slow motion' low-exponent Lévy fractional diffusion smoothing. This combined approach is unexpectedly effective, resulting in a companion enhanced image in which background structures are rendered much more visible, and noise is significantly reduced, all with minimal loss of image sharpness. The method also provides useful enhancements of scanning charged-particle microscopy images obtained by composing multiple drift-corrected 'fast scan' frames. The paper includes software routines, written in Interactive Data Language (IDL),(1) that can perform the above image processing tasks.

Performance-Driven Hybrid Full-Body Character Control for Navigation and Interaction in Virtual Environments

NASA Astrophysics Data System (ADS)

Mousas, Christos; Anagnostopoulos, Christos-Nikolaos

2017-06-01

This paper presents a hybrid character control interface that provides the ability to synthesize in real-time a variety of actions based on the user's performance capture. The proposed methodology enables three different performance interaction modules: the performance animation control that enables the direct mapping of the user's pose to the character, the motion controller that synthesizes the desired motion of the character based on an activity recognition methodology, and the hybrid control that lies within the performance animation and the motion controller. With the methodology presented, the user will have the freedom to interact within the virtual environment, as well as the ability to manipulate the character and to synthesize a variety of actions that cannot be performed directly by him/her, but which the system synthesizes. Therefore, the user is able to interact with the virtual environment in a more sophisticated fashion. This paper presents examples of different scenarios based on the three different full-body character control methodologies.

Nanoparticle Brownian motion and hydrodynamic interactions in the presence of flow fields

PubMed Central

Uma, B.; Swaminathan, T. N.; Radhakrishnan, R.; Eckmann, D. M.; Ayyaswamy, P. S.

2011-01-01

We consider the Brownian motion of a nanoparticle in an incompressible Newtonian fluid medium (quiescent or fully developed Poiseuille flow) with the fluctuating hydrodynamics approach. The formalism considers situations where both the Brownian motion and the hydrodynamic interactions are important. The flow results have been modified to account for compressibility effects. Different nanoparticle sizes and nearly neutrally buoyant particle densities are also considered. Tracked particles are initially located at various distances from the bounding wall to delineate wall effects. The results for thermal equilibrium are validated by comparing the predictions for the temperatures of the particle with those obtained from the equipartition theorem. The nature of the hydrodynamic interactions is verified by comparing the velocity autocorrelation functions and mean square displacements with analytical and experimental results where available. The equipartition theorem for a Brownian particle in Poiseuille flow is verified for a range of low Reynolds numbers. Numerical predictions of wall interactions with the particle in terms of particle diffusivities are consistent with results, where available. PMID:21918592

Risk assessment of flange climb derailment of a rail vehicle

NASA Astrophysics Data System (ADS)

Vlakhova, A. V.

2015-01-01

We study the wheel flange climb onto the railhead, which is one of the most dangerous regimes of motion and can lead to derailment. The tangential components of the wheel-rail interaction forces are described by the creep model with small slips taken into account. We pass to the limit of infinite rigidity of the interacting bodies (zero slip velocities). It is shown that, in the actual service conditions of rail vehicle motion, neglecting the wheel-rail slip is not justified; namely, the limit model is determined by the primary Dirac constraints, i.e., finite relations between coordinates and momenta arising owing to the system Lagrangian degeneration. The obtained nonclassical model allows one to study the efficiency of some railway motion safety criteria and analytically estimate derailment conditions, which depend on the flange shape, the track curvature radius, the height of the vehicle center of mass, the wheel-rail interaction forces, the coefficients of friction of the interacting surfaces, and the external perturbation forces and moments.

Fluctuation-induced transport of two coupled particles: effect of the interparticle interaction.

PubMed

Makhnovskii, Yurii A; Rozenbaum, Viktor M; Sheu, Sheh-Yi; Yang, Dah-Yen; Trakhtenberg, Leonid I; Lin, Sheng Hsien

2014-06-07

We consider a system of two coupled particles fluctuating between two states, with different interparticle interaction potentials and particle friction coefficients. An external action drives the interstate transitions that induces reciprocating motion along the internal coordinate x (the interparticle distance). The system moves unidirectionally due to rectification of the internal motion by asymmetric friction fluctuations and thus operates as a dimeric motor that converts input energy into net movement. We focus on how the law of interaction between the particles affects the dimer transport and, in particular, the role of thermal noise in the motion inducing mechanism. It is argued that if the interaction potential behaves at large distances as x(α), depending on the value of the exponent α, the thermal noise plays a constructive (α > 2), neutral (α = 2), or destructive (α < 2) role. In the case of α = 1, corresponding piecewise linear potential profiles, an exact solution is obtained and discussed in detail.

Extreme fluctuations of active Brownian motion

NASA Astrophysics Data System (ADS)

Pietzonka, Patrick; Kleinbeck, Kevin; Seifert, Udo

2016-05-01

In active Brownian motion, an internal propulsion mechanism interacts with translational and rotational thermal noise and other internal fluctuations to produce directed motion. We derive the distribution of its extreme fluctuations and identify its universal properties using large deviation theory. The limits of slow and fast internal dynamics give rise to a kink-like and parabolic behavior of the corresponding rate functions, respectively. For dipolar Janus particles in two- and three-dimensions interacting with a field, we predict a novel symmetry akin to, but different from, the one related to entropy production. Measurements of these extreme fluctuations could thus be used to infer properties of the underlying, often hidden, network of states.

Binocular Interactions Underlying the Classic Optomotor Responses of Flying Flies

PubMed Central

Duistermars, Brian J.; Care, Rachel A.; Frye, Mark A.

2012-01-01

In response to imposed course deviations, the optomotor reactions of animals reduce motion blur and facilitate the maintenance of stable body posture. In flies, many anatomical and electrophysiological studies suggest that disparate motion cues stimulating the left and right eyes are not processed in isolation but rather are integrated in the brain to produce a cohesive panoramic percept. To investigate the strength of such inter-ocular interactions and their role in compensatory sensory–motor transformations, we utilize a virtual reality flight simulator to record wing and head optomotor reactions by tethered flying flies in response to imposed binocular rotation and monocular front-to-back and back-to-front motion. Within a narrow range of stimulus parameters that generates large contrast insensitive optomotor responses to binocular rotation, we find that responses to monocular front-to-back motion are larger than those to panoramic rotation, but are contrast sensitive. Conversely, responses to monocular back-to-front motion are slower than those to rotation and peak at the lowest tested contrast. Together our results suggest that optomotor responses to binocular rotation result from the influence of non-additive contralateral inhibitory as well as excitatory circuit interactions that serve to confer contrast insensitivity to flight behaviors influenced by rotatory optic flow. PMID:22375108

Simulating the dynamic interaction of a robotic arm and the Space Shuttle remote manipulator system. M.S. Thesis - George Washington Univ., Dec. 1994

NASA Technical Reports Server (NTRS)

Garrahan, Steven L.; Tolson, Robert H.; Williams, Robert L., II

1995-01-01

Industrial robots are usually attached to a rigid base. Placing the robot on a compliant base introduces dynamic coupling between the two systems. The Vehicle Emulation System (VES) is a six DOF platform that is capable of modeling this interaction. The VES employs a force-torque sensor as the interface between robot and base. A computer simulation of the VES is presented. Each of the hardware and software components is described and Simulink is used as the programming environment. The simulation performance is compared with experimental results to validate accuracy. A second simulation which models the dynamic interaction of a robot and a flexible base acts as a comparison to the simulated motion of the VES. Results are presented that compare the simulated VES motion with the motion of the VES hardware using the same admittance model. The two computer simulations are compared to determine how well the VES is expected to emulate the desired motion. Simulation results are given for robots mounted to the end effector of the Space Shuttle Remote Manipulator System (SRMS). It is shown that for fast motions of the two robots studied, the SRMS experiences disturbances on the order of centimeters. Larger disturbances are possible if different manipulators are used.

Thermal drift is enough to drive a single microtubule along its axis even in the absence of motor proteins.

PubMed Central

Nakata, T; Sato-Yoshitake, R; Okada, Y; Noda, Y; Hirokawa, N

1993-01-01

One-dimensional diffusion of microtubules (MTs), a back-and-forth motion of MTs due to thermal diffusion, was reported in dynein motility assay. The interaction between MTs and dynein that allows such motion was implicated in its importance in the force generating cycle of dynein ATPase cycle. However, it was not known whether the phenomenon is special to motor proteins. Here we show two independent examples of one-dimensional diffusion of MTs in the absence of motor proteins. Dynamin, a MT-activated GTPase, causes a nucleotide dependent back-and-forth movement of single MT up to 1 micron along the longitudinal axes, although the MT never showed unidirectional consistent movement. Quantitative analysis of the motion and its nucleotide condition indicates that the motion is due to a thermal driven diffusion, restricted to one dimension, under the weak interaction between MT and dynamin. However, specific protein-protein interaction is not essential for the motion, because similar back-and-forth movement of MT was achieved on coverslips coated with only 0.8% methylcellulose. Both cases demonstrate that thermal diffusion could provide a considerable sliding of MTs only if MTs are restricted on the surface appropriately. Images FIGURE 1 FIGURE 2 FIGURE 3 PMID:7906153

Computer vision-based technologies and commercial best practices for the advancement of the motion imagery tradecraft

NASA Astrophysics Data System (ADS)

Phipps, Marja; Capel, David; Srinivasan, James

2014-06-01

Motion imagery capabilities within the Department of Defense/Intelligence Community (DoD/IC) have advanced significantly over the last decade, attempting to meet continuously growing data collection, video processing and analytical demands in operationally challenging environments. The motion imagery tradecraft has evolved accordingly, enabling teams of analysts to effectively exploit data and generate intelligence reports across multiple phases in structured Full Motion Video (FMV) Processing Exploitation and Dissemination (PED) cells. Yet now the operational requirements are drastically changing. The exponential growth in motion imagery data continues, but to this the community adds multi-INT data, interoperability with existing and emerging systems, expanded data access, nontraditional users, collaboration, automation, and support for ad hoc configurations beyond the current FMV PED cells. To break from the legacy system lifecycle, we look towards a technology application and commercial adoption model course which will meet these future Intelligence, Surveillance and Reconnaissance (ISR) challenges. In this paper, we explore the application of cutting edge computer vision technology to meet existing FMV PED shortfalls and address future capability gaps. For example, real-time georegistration services developed from computer-vision-based feature tracking, multiple-view geometry, and statistical methods allow the fusion of motion imagery with other georeferenced information sources - providing unparalleled situational awareness. We then describe how these motion imagery capabilities may be readily deployed in a dynamically integrated analytical environment; employing an extensible framework, leveraging scalable enterprise-wide infrastructure and following commercial best practices.

Origin scenarios for the Kepler 36 planetary system

NASA Astrophysics Data System (ADS)

Quillen, Alice C.; Bodman, Eva; Moore, Alexander

2013-11-01

We explore scenarios for the origin of two different density planets in the Kepler 36 system in adjacent orbits near the 7:6 mean motion resonance. We find that fine tuning is required in the stochastic forcing amplitude, the migration rate and planet eccentricities to allow two convergently migrating planets to bypass mean motion resonances such as the 4:3, 5:4 and 6:5, and yet allow capture into the 7:6 resonance. Stochastic forcing can eject the system from resonance causing a collision between the planets, unless the disc causing migration and stochastic forcing is depleted soon after resonance capture. We explore a scenario with approximately Mars mass embryos originating exterior to the two planets and migrating inwards towards two planets. We find that gravitational interactions with embryos can nudge the system out of resonances. Numerical integrations with about a half dozen embryos can leave the two planets in the 7:6 resonance. Collisions between planets and embryos have a wide distribution of impact angles and velocities ranging from accretionary to disruptive. We find that impacts can occur at sufficiently high impact angle and velocity that the envelope of a planet could have been stripped, leaving behind a dense core. Some of our integrations show the two planets exchanging locations, allowing the outer planet that had experienced multiple collisions with embryos to become the innermost planet. A scenario involving gravitational interactions and collisions with embryos may account for both the proximity of the Kepler 36 planets and their large density contrast.

Conformational Changes in the Epidermal Growth Factor Receptor: Role of the Transmembrane Domain Investigated by Coarse-Grained MetaDynamics Free Energy Calculations

PubMed Central

2016-01-01

The epidermal growth factor receptor (EGFR) is a dimeric membrane protein that regulates key aspects of cellular function. Activation of the EGFR is linked to changes in the conformation of the transmembrane (TM) domain, brought about by changes in interactions of the TM helices of the membrane lipid bilayer. Using an advanced computational approach that combines Coarse-Grained molecular dynamics and well-tempered MetaDynamics (CG-MetaD), we characterize the large-scale motions of the TM helices, simulating multiple association and dissociation events between the helices in membrane, thus leading to a free energy landscape of the dimerization process. The lowest energy state of the TM domain is a right-handed dimer structure in which the TM helices interact through the N-terminal small-X3-small sequence motif. In addition to this state, which is thought to correspond to the active form of the receptor, we have identified further low-energy states that allow us to integrate with a high level of detail a range of previous experimental observations. These conformations may lead to the active state via two possible activation pathways, which involve pivoting and rotational motions of the helices, respectively. Molecular dynamics also reveals correlation between the conformational changes of the TM domains and of the intracellular juxtamembrane domains, paving the way for a comprehensive understanding of EGFR signaling at the cell membrane. PMID:27459426

Conformational Changes in the Epidermal Growth Factor Receptor: Role of the Transmembrane Domain Investigated by Coarse-Grained MetaDynamics Free Energy Calculations.

PubMed

Lelimousin, Mickaël; Limongelli, Vittorio; Sansom, Mark S P

2016-08-24

The epidermal growth factor receptor (EGFR) is a dimeric membrane protein that regulates key aspects of cellular function. Activation of the EGFR is linked to changes in the conformation of the transmembrane (TM) domain, brought about by changes in interactions of the TM helices of the membrane lipid bilayer. Using an advanced computational approach that combines Coarse-Grained molecular dynamics and well-tempered MetaDynamics (CG-MetaD), we characterize the large-scale motions of the TM helices, simulating multiple association and dissociation events between the helices in membrane, thus leading to a free energy landscape of the dimerization process. The lowest energy state of the TM domain is a right-handed dimer structure in which the TM helices interact through the N-terminal small-X3-small sequence motif. In addition to this state, which is thought to correspond to the active form of the receptor, we have identified further low-energy states that allow us to integrate with a high level of detail a range of previous experimental observations. These conformations may lead to the active state via two possible activation pathways, which involve pivoting and rotational motions of the helices, respectively. Molecular dynamics also reveals correlation between the conformational changes of the TM domains and of the intracellular juxtamembrane domains, paving the way for a comprehensive understanding of EGFR signaling at the cell membrane.

Kinetic theory of passing energetic ion transport in presence of the resonant interactions with a rotating magnetic island

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

Cao, Jinjia; Gong, Xueyu; Xiang, Dong

The enhanced transport of passing energetic ions (PEIs) in presence of the resonant interactions with a rotating magnetic island is investigated within the drift kinetic framework. When the island rotation plays a role in the resonant interaction, we find that the velocities of PEIs satisfy a constraint relation of resonant flux surface in phase space. The resonant flux surfaces overlap with the magnetic flux surfaces in real space. A new transport channel responsible for the PEIs moving across the magnetic flux surfaces, i.e., continuously overlapping, is found. Two kinds of radial motions can be induced by the surface overlapping: onemore » arises from the coupling between the resonance and the collision with the background plasma and the other from not completely overlapping of the two surfaces. The two radial motions and the symmetry-breaking induced radial motion constitute the total radial motion. When the pitch-angle scattering rate is very weak, the surface-shear induced transport is dominant. Only a small increase in the collision rate can significantly influence the total transport.« less

The optional selection of micro-motion feature based on Support Vector Machine

NASA Astrophysics Data System (ADS)

Li, Bo; Ren, Hongmei; Xiao, Zhi-he; Sheng, Jing

2017-11-01

Micro-motion form of target is multiple, different micro-motion forms are apt to be modulated, which makes it difficult for feature extraction and recognition. Aiming at feature extraction of cone-shaped objects with different micro-motion forms, this paper proposes the best selection method of micro-motion feature based on support vector machine. After the time-frequency distribution of radar echoes, comparing the time-frequency spectrum of objects with different micro-motion forms, features are extracted based on the differences between the instantaneous frequency variations of different micro-motions. According to the methods based on SVM (Support Vector Machine) features are extracted, then the best features are acquired. Finally, the result shows the method proposed in this paper is feasible under the test condition of certain signal-to-noise ratio(SNR).

Spin-wave-driven high-speed domain-wall motions in soft magnetic nanotubes

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

Yang, Jaehak; Yoo, Myoung-Woo; Kim, Sang-Koog, E-mail: sangkoog@snu.ac.kr

We report on a micromagnetic simulation study of interactions between propagating spin waves and a head-to-head domain wall in geometrically confined magnetic nanotubes. We found that incident spin waves of specific frequencies can lead to sufficiently high-speed (on the order of a few hundreds of m/s or higher) domain-wall motions in the same direction as that of the incident spin-waves. The domain-wall motions and their speed vary remarkably with the frequency and the amplitude of the incident spin-waves. High-speed domain-wall motions originate from the transfer torque of spin waves' linear momentum to the domain wall, through the partial or completemore » reflection of the incident spin waves from the domain wall. This work provides a fundamental understanding of the interaction of the spin waves with a domain wall in the magnetic nanotubes as well as a route to all-magnetic control of domain-wall motions in the magnetic nanoelements.« less

Turning Passive Brownian Motion Into Active Motion

NASA Astrophysics Data System (ADS)

Sevilla, Francisco J.; VáSquez-Arzola, Alejandro; Puga-Cital, Enrique

We consider out-of-equilibrium phenomena, specifically, the pattern of motion of active particles. These particles absorb energy from the environment and transform it into self-locomotion, generally, through complex mechanisms. Though the out-of-equilibrium nature of on the motion of these systems is well recognized, is generally difficult to pinpoint how far from equilibrium these systems are. In this work we elucidate the out-of-equilibrium nature of non-interacting, trapped, active particles, whose pattern of motion is described by a run-and-tumble dynamics. We show that the stationary distributions of these run-and-tumble particles, moving under the effects of an external potential, is equivalent to the stationary distribution of non-interacting, passive Brownian particles moving in the same potential but in an inhomogeneous source of heat. The interest in this topic has recently regrown due to the experimental possibility to design man-made active particles that emulate the ones that exist in the biological realm. F.J.S kindly acknowledges support from Grant UNAM-DGAPA-PAPIIT-IN113114.

As time passes by: Observed motion-speed and psychological time during video playback.

PubMed

Nyman, Thomas Jonathan; Karlsson, Eric Per Anders; Antfolk, Jan

2017-01-01

Research shows that psychological time (i.e., the subjective experience and assessment of the passage of time) is malleable and that the central nervous system re-calibrates temporal information in accordance with situational factors so that psychological time flows slower or faster. Observed motion-speed (e.g., the visual perception of a rolling ball) is an important situational factor which influences the production of time estimates. The present study examines previous findings showing that observed slow and fast motion-speed during video playback respectively results in over- and underproductions of intervals of time. Here, we investigated through three separate experiments: a) the main effect of observed motion-speed during video playback on a time production task and b) the interactive effect of the frame rate (frames per second; fps) and motion-speed during video playback on a time production task. No main effect of video playback-speed or interactive effect between video playback-speed and frame rate was found on time production.

As time passes by: Observed motion-speed and psychological time during video playback

PubMed Central

Karlsson, Eric Per Anders; Antfolk, Jan

2017-01-01

Research shows that psychological time (i.e., the subjective experience and assessment of the passage of time) is malleable and that the central nervous system re-calibrates temporal information in accordance with situational factors so that psychological time flows slower or faster. Observed motion-speed (e.g., the visual perception of a rolling ball) is an important situational factor which influences the production of time estimates. The present study examines previous findings showing that observed slow and fast motion-speed during video playback respectively results in over- and underproductions of intervals of time. Here, we investigated through three separate experiments: a) the main effect of observed motion-speed during video playback on a time production task and b) the interactive effect of the frame rate (frames per second; fps) and motion-speed during video playback on a time production task. No main effect of video playback-speed or interactive effect between video playback-speed and frame rate was found on time production. PMID:28614353

Encodings of implied motion for animate and inanimate object categories in the two visual pathways.

PubMed

Lu, Zhengang; Li, Xueting; Meng, Ming

2016-01-15

Previous research has proposed two separate pathways for visual processing: the dorsal pathway for "where" information vs. the ventral pathway for "what" information. Interestingly, the middle temporal cortex (MT) in the dorsal pathway is involved in representing implied motion from still pictures, suggesting an interaction between motion and object related processing. However, the relationship between how the brain encodes implied motion and how the brain encodes object/scene categories is unclear. To address this question, fMRI was used to measure activity along the two pathways corresponding to different animate and inanimate categories of still pictures with different levels of implied motion speed. In the visual areas of both pathways, activity induced by pictures of humans and animals was hardly modulated by the implied motion speed. By contrast, activity in these areas correlated with the implied motion speed for pictures of inanimate objects and scenes. The interaction between implied motion speed and stimuli category was significant, suggesting different encoding mechanisms of implied motion for animate-inanimate distinction. Further multivariate pattern analysis of activity in the dorsal pathway revealed significant effects of stimulus category that are comparable to the ventral pathway. Moreover, still pictures of inanimate objects/scenes with higher implied motion speed evoked activation patterns that were difficult to differentiate from those evoked by pictures of humans and animals, indicating a functional role of implied motion in the representation of object categories. These results provide novel evidence to support integrated encoding of motion and object categories, suggesting a rethink of the relationship between the two visual pathways. Copyright © 2015 Elsevier Inc. All rights reserved.

Touch-free, gesture-based control of medical devices and software based on the leap motion controller.

PubMed

Mauser, Stanislas; Burgert, Oliver

2014-01-01

There are several intra-operative use cases which require the surgeon to interact with medical devices. We used the Leap Motion Controller as input device and implemented two use-cases: 2D-Interaction (e.g. advancing EPR data) and selection of a value (e.g. room illumination brightness). The gesture detection was successful and we mapped its output to several devices and systems.

Unreal Interactive Puppet Game Development Using Leap Motion

NASA Astrophysics Data System (ADS)

Huang, An-Pin; Huang, Fay; Jhu, Jing-Siang

2018-04-01

This paper proposed a novel puppet play method utilizing recent technology. An interactive puppet game has been developed based on the theme of a famous Chinese classical novel. This project was implemented using Unreal Engine, which is a leading software of integrated tools for developers to design and build games. On the other hand, Leap Motion Controller is a sensor device for recognizing hand movements and gestures. It is commonly used in systems which require close-range finger-based user interaction. In order to manipulate puppets’ movements, the developed program employs the Leap Motion SDK, which provides a friendly way to add motion-controlled 3D hands to an Unreal game. The novelty of our project is to replace 3D model of rigged hands by two 3D humanoid rigged characters. The challenges of this task are two folds. First, the skeleton structure of a human hand and a humanoid character (i.e., puppets) are totally different. Making the puppets to follow the hand poses of the user and yet ensuring reasonable puppets’ movements has not been discussed in the literatures nor in the developer forums. Second, there are only a limited number of built-in recognizable hand gestures. More recognizable hand gestures need to be created for the interactive game. This paper reports the proposed solutions to these challenges.

Comparative Study on Interaction of Form and Motion Processing Streams by Applying Two Different Classifiers in Mechanism for Recognition of Biological Movement

PubMed Central

2014-01-01

Research on psychophysics, neurophysiology, and functional imaging shows particular representation of biological movements which contains two pathways. The visual perception of biological movements formed through the visual system called dorsal and ventral processing streams. Ventral processing stream is associated with the form information extraction; on the other hand, dorsal processing stream provides motion information. Active basic model (ABM) as hierarchical representation of the human object had revealed novelty in form pathway due to applying Gabor based supervised object recognition method. It creates more biological plausibility along with similarity with original model. Fuzzy inference system is used for motion pattern information in motion pathway creating more robustness in recognition process. Besides, interaction of these paths is intriguing and many studies in various fields considered it. Here, the interaction of the pathways to get more appropriated results has been investigated. Extreme learning machine (ELM) has been implied for classification unit of this model, due to having the main properties of artificial neural networks, but crosses from the difficulty of training time substantially diminished in it. Here, there will be a comparison between two different configurations, interactions using synergetic neural network and ELM, in terms of accuracy and compatibility. PMID:25276860

Toward Multimodal Human-Robot Interaction to Enhance Active Participation of Users in Gait Rehabilitation.

PubMed

Gui, Kai; Liu, Honghai; Zhang, Dingguo

2017-11-01

Robotic exoskeletons for physical rehabilitation have been utilized for retraining patients suffering from paraplegia and enhancing motor recovery in recent years. However, users are not voluntarily involved in most systems. This paper aims to develop a locomotion trainer with multiple gait patterns, which can be controlled by the active motion intention of users. A multimodal human-robot interaction (HRI) system is established to enhance subject's active participation during gait rehabilitation, which includes cognitive HRI (cHRI) and physical HRI (pHRI). The cHRI adopts brain-computer interface based on steady-state visual evoked potential. The pHRI is realized via admittance control based on electromyography. A central pattern generator is utilized to produce rhythmic and continuous lower joint trajectories, and its state variables are regulated by cHRI and pHRI. A custom-made leg exoskeleton prototype with the proposed multimodal HRI is tested on healthy subjects and stroke patients. The results show that voluntary and active participation can be effectively involved to achieve various assistive gait patterns.

Hybrid Methods Reveal Multiple Flexibly Linked DNA Polymerases within the Bacteriophage T7 Replisome

DOE PAGES

Wallen, Jamie R.; Zhang, Hao; Weis, Caroline; ...

2017-01-03

The physical organization of DNA enzymes at a replication fork enables efficient copying of two antiparallel DNA strands, yet dynamic protein interactions within the replication complex complicate replisome structural studies. We employed a combination of crystallographic, native mass spectrometry and small-angle X-ray scattering experiments to capture alternative structures of a model replication system encoded by bacteriophage T7. then, the two molecules of DNA polymerase bind the ring-shaped primase-helicase in a conserved orientation and provide structural insight into how the acidic C-terminal tail of the primase-helicase contacts the DNA polymerase to facilitate loading of the polymerase onto DNA. A third DNA polymerasemore » binds the ring in an offset manner that may enable polymerase exchange during replication. Alternative polymerase binding modes are also detected by small-angle X-ray scattering with DNA substrates present. The collective results unveil complex motions within T7 replisome higher-order structures that are underpinned by multivalent protein-protein interactions with functional implications.« less

Drawing Lines with Light in Holographic Space

NASA Astrophysics Data System (ADS)

Chang, Yin-Ren; Richardson, Martin

2013-02-01

This paper explores the dynamic and expressive possibilities of holographic art through a comparison of art history and technical media such as photography, film and holographic technologies. Examples of modern art and creative expression of time and motions are examined using the early 20th century art movement, Cubism, where subjects are portrayed to be seen simultaneously from different angles. Folding space is represented as subject matter as it can depict space from multiple points of time. The paper also investigates the way holographic art has explored time and space. The lenticular lens-based media reveal a more subjective poetic art in the form of the lyrical images and messages as spectators pass through time, or walk along with the piece of work through an interactive process. It is argued that photographic practice is another example of artistic representation in the form of aesthetic medium of time movement and as such shares a common ground with other dynamic expression that require time based interaction.

Hybrid Methods Reveal Multiple Flexibly Linked DNA Polymerases within the Bacteriophage T7 Replisome

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

Wallen, Jamie R.; Zhang, Hao; Weis, Caroline

The physical organization of DNA enzymes at a replication fork enables efficient copying of two antiparallel DNA strands, yet dynamic protein interactions within the replication complex complicate replisome structural studies. We employed a combination of crystallographic, native mass spectrometry and small-angle X-ray scattering experiments to capture alternative structures of a model replication system encoded by bacteriophage T7. then, the two molecules of DNA polymerase bind the ring-shaped primase-helicase in a conserved orientation and provide structural insight into how the acidic C-terminal tail of the primase-helicase contacts the DNA polymerase to facilitate loading of the polymerase onto DNA. A third DNA polymerasemore » binds the ring in an offset manner that may enable polymerase exchange during replication. Alternative polymerase binding modes are also detected by small-angle X-ray scattering with DNA substrates present. The collective results unveil complex motions within T7 replisome higher-order structures that are underpinned by multivalent protein-protein interactions with functional implications.« less

IB2d: a Python and MATLAB implementation of the immersed boundary method.

PubMed

Battista, Nicholas A; Strickland, W Christopher; Miller, Laura A

2017-03-29

The development of fluid-structure interaction (FSI) software involves trade-offs between ease of use, generality, performance, and cost. Typically there are large learning curves when using low-level software to model the interaction of an elastic structure immersed in a uniform density fluid. Many existing codes are not publicly available, and the commercial software that exists usually requires expensive licenses and may not be as robust or allow the necessary flexibility that in house codes can provide. We present an open source immersed boundary software package, IB2d, with full implementations in both MATLAB and Python, that is capable of running a vast range of biomechanics models and is accessible to scientists who have experience in high-level programming environments. IB2d contains multiple options for constructing material properties of the fiber structure, as well as the advection-diffusion of a chemical gradient, muscle mechanics models, and artificial forcing to drive boundaries with a preferred motion.

Positron transport in solids and the interaction of positrons with surfaces

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

Kong, Yuan.

1991-01-01

In studying positron transport in solids, a two-stream model is proposed to account for the epithermal positrons. Thus positron implantation, thermalization, and diffusion processes are completely modeled. Experimentally, positron mobility in thermally grown SiO[sub 2] is measured in a sandwiched structure by using the Doppler broadening technique. Positron drift motion and the electric field configuration in a Si surface buried under overlayers are measured with the positron annihilation [gamma]-ray centroid shift technique. These studies are not only important in measuring positron transport and other properties in complicated systems, they are also of practical significance for material characterizations. In studying positronmore » interactions with surfaces, a multiple-encounter picture is proposed of thermal positrons participating in the surface escape processes. Positron trapping into the surface image potential is also studied, considering the long-range nature of the image potential. Experimentally, the positron annihilation induced Auger electron spectroscopy (PAES) is used to study an ionic insulator surface KCl(100).« less

Novel permanent magnet linear motor with isolated movers: analytical, numerical and experimental study.

PubMed

Yan, Liang; Peng, Juanjuan; Jiao, Zongxia; Chen, Chin-Yin; Chen, I-Ming

2014-10-01

This paper proposes a novel permanent magnet linear motor possessing two movers and one stator. The two movers are isolated and can interact with the stator poles to generate independent forces and motions. Compared with conventional multiple motor driving system, it helps to increase the system compactness, and thus improve the power density and working efficiency. The magnetic field distribution is obtained by using equivalent magnetic circuit method. Following that, the formulation of force output considering armature reaction is carried out. Then inductances are analyzed with finite element method to investigate the relationships of the two movers. It is found that the mutual-inductances are nearly equal to zero, and thus the interaction between the two movers is negligible. A research prototype of the linear motor and a measurement apparatus on thrust force have been developed. Both numerical computation and experiment measurement are conducted to validate the analytical model of thrust force. Comparison shows that the analytical model matches the numerical and experimental results well.

Simulations of Heterogeneous Detonations and Post Detonation Turbulent Mixing and Afterburning

NASA Astrophysics Data System (ADS)

Menon, Suresh; Gottiparthi, Kalyana

2011-06-01

Most metal-loaded explosives and thermobaric explosives exploit the afterburning of metals to maintain pressure and temperature conditions.The use of such explosives in complex environment can result in post detonation flow containing many scales of vortical motion, flow jetting and shear, as well as plume-surface interactions due to flow impingement and wall flows. In general, all these interactions can lead to highly turbulent flow fields even if the initial ambient conditions were quiescent. Thus, turbulent mixing can dominate initial mixing and impact the final afterburn. We conduct three-dimensional numerical simulations of the propagation of detonation resulting from metal-loaded (inert or reacting) explosives and analyze the afterburn process as well as the generation of multiple scales of mixing in the post detonation flow field. Impact of the detonation and post-detonation flow field on solid surface is also considered for a variety of initial conditions. Comparison with available data is carried out to demonstrate validity of the simulation method. Supported by Defense Threat Reduction Agency

Multiple Teaching Approaches, Teaching Sequence and Concept Retention in High School Physics Education

ERIC Educational Resources Information Center

Fogarty, Ian; Geelan, David

2013-01-01

Students in 4 Canadian high school physics classes completed instructional sequences in two key physics topics related to motion--Straight Line Motion and Newton's First Law. Different sequences of laboratory investigation, teacher explanation (lecture) and the use of computer-based scientific visualizations (animations and simulations) were…

Liquid Motion Lamp: A Learning-Cycle Approach to Solubility

ERIC Educational Resources Information Center

Brown, Sherri L.; Votaw, Nikki L.

2008-01-01

The abstract concepts of density and solubility are often difficult for middle-grade students and should be taught within several contexts to provide multiple experiences with the phenomena. To authenticate the learning of these concepts, this article provides instructional guidelines for constructing a liquid motion lamp to engage students in…

Temporal Frequency Modulates Reaction Time Responses to First-Order and Second-Order Motion

ERIC Educational Resources Information Center

Hutchinson, Claire V.; Ledgeway, Tim

2010-01-01

This study investigated the effect of temporal frequency and modulation depth on reaction times for discriminating the direction of first-order (luminance-defined) and second-order (contrast-defined) motion, equated for visibility using equal multiples of direction-discrimination threshold. Results showed that reaction times were heavily…

Cyclic and Coherent States in Flocks with Topological Distance

NASA Astrophysics Data System (ADS)

Bhattacherjee, Biplab; Bhattacharya, Kunal; Manna, Subhrangshu

2014-01-01

A simple model of the two dimensional collective motion of a group of mobile agents have been studied. Like birds, these agents travel in open free space where each of them interacts with the first n neighbors determined by the topological distance with a free boundary condition. Using the same prescription for interactions used in the Vicsek model with scalar noise it has been observed that the flock, in absence of the noise, arrives at a number of interesting stationary states. One of the two most prominent states is the `single sink state' where the entire flock travels along the same direction maintaining perfect cohesion and coherence. The other state is the `cyclic state' where every individual agent executes a uniform circular motion, and the correlation among the agents guarantees that the entire flock executes a pulsating dynamics i.e., expands and contracts periodically between a minimum and a maximum size of the flock. We have studied another limiting situation when refreshing rate of the interaction zone is the fastest. In this case the entire flock gets fragmented into smaller clusters of different sizes. On introduction of scalar noise a crossover is observed when the agents cross over from a ballistic motion to a diffusive motion. Expectedly the crossover time is dependent on the strength of the noise η and diverges as η → 0. An even more simpler version of this model has been studied by suppressing the translational degrees of freedom of the agents but retaining their angular motion. Here agents are the spins, placed at the sites of a square lattice with periodic boundary condition. Every spin interacts with its n = 2, 3 or 4 nearest neighbors. In the stationary state the entire spin pattern moves as a whole when interactions are anisotropic with n = 2 and 3; but it is completely frozen when the interaction is isotropic with n=4$. These spin configu

Controlled Wake of a Moving Axisymmetric Bluff Body

NASA Astrophysics Data System (ADS)

Lee, E.; Vukasinovic, B.; Glezer, A.

2017-11-01

The aerodynamic loads exerted on a wire-mounted axisymmetric bluff body in prescribed rigid motion are controlled by fluidic manipulation of its near wake. The body is supported by a six-degree of freedom eight-wire traverse and its motion is controlled using a dedicated servo actuator and inline load cell for each wire. The instantaneous aerodynamic forces and moments on the moving body are manipulated by controlled interactions of an azimuthal array of integrated synthetic jet actuators with the cross flow to induce localized flow attachment over the body's aft end and thereby alter the symmetry of the wake. The coupled interactions between the wake structure and the effected aerodynamic loads during prescribed time-periodic and transitory (gust like) motions are investigated with emphasis on enhancing or diminishing the loads for maneuver control, and decoupling the body's motion from its far wake.

Analysis of Timing Control Mechanism of Utterance and Body Motion Using Dialogue between Human and Communication Robot

NASA Astrophysics Data System (ADS)

Takasugi, Shoji; Yamamoto, Tomohito; Muto, Yumiko; Abe, Hiroyuki; Miyake, Yoshihiro

The purpose of this study is to clarify the effects of timing control of utterance and body motion in human-robot interaction. Our previous study has already revealed the correlation of timing of utterance and body motion in human-human communication. Here we proposed a timing control model based on our previous research and estimated its influence to realize human-like communication using a questionnaire method. The results showed that the difference of effectiveness between the communication with the timing control model and that without it was observed. In addition, elderly people evaluated the communication with timing control much higher than younger people. These results show not only the importance of timing control of utterance and body motion in human communication but also its effectiveness for realizing human-like human-robot interaction.

Free vibration of multiwall carbon nanotubes

NASA Astrophysics Data System (ADS)

Wang, C. Y.; Ru, C. Q.; Mioduchowski, A.

2005-06-01

A multiple-elastic shell model is applied to systematically study free vibration of multiwall carbon nanotubes (MWNTs). Using Flugge [Stresses in Shells (Springer, Berlin, 1960)] equations of elastic shells, vibrational frequencies and associated modes are calculated for MWNTs of innermost radii 5 and 0.65 nm, respectively. The emphasis is placed on the effect of interlayer van der Waals (vdW) interaction on free vibration of MWNTs. Our results show that the interlayer vdW interaction has a crucial effect on radial (R) modes of large-radius MWNTs (e.g., of the innermost radius 5 nm), but is less pronounced for R modes of small-radius MWNTs (e.g., of the innermost radius 0.65 nm), and usually negligible for torsional (T) and longitudinal (L) modes of MWNTs. This is attributed to the fact that the interlayer vdW interaction, characterized by a radius-independent vdW interaction coefficient, depends on radial deflections only, and is dominant only for large-radius MWNTs of lower radial rigidity but less pronounced for small-radius MWNTs of much higher radial rigidity. As a result, the R modes of large-radius MWNTs are typically collective motions of almost all nested tubes, and the R modes of small-radius MWNTs, as well as the T and L modes of MWNTs, are basically vibrations of individual tubes. In particular, an approximate single-shell model is suggested to replace the multiple-shell model in calculating the lowest frequency of R mode of thin MWNTs (defined by the innermost radius-to-thickness ratio not less than 4) with relative errors less than 10%. In addition, the simplified Flugge single equation is adopted to substitute the exact Flugge equations in determining the R-mode frequencies of MWNTs with relative errors less than 10%.

MUNDUS project: MUltimodal neuroprosthesis for daily upper limb support.

PubMed

Pedrocchi, Alessandra; Ferrante, Simona; Ambrosini, Emilia; Gandolla, Marta; Casellato, Claudia; Schauer, Thomas; Klauer, Christian; Pascual, Javier; Vidaurre, Carmen; Gföhler, Margit; Reichenfelser, Werner; Karner, Jakob; Micera, Silvestro; Crema, Andrea; Molteni, Franco; Rossini, Mauro; Palumbo, Giovanna; Guanziroli, Eleonora; Jedlitschka, Andreas; Hack, Marco; Bulgheroni, Maria; d'Amico, Enrico; Schenk, Peter; Zwicker, Sven; Duschau-Wicke, Alexander; Miseikis, Justinas; Graber, Lina; Ferrigno, Giancarlo

2013-07-03

MUNDUS is an assistive framework for recovering direct interaction capability of severely motor impaired people based on arm reaching and hand functions. It aims at achieving personalization, modularity and maximization of the user's direct involvement in assistive systems. To this, MUNDUS exploits any residual control of the end-user and can be adapted to the level of severity or to the progression of the disease allowing the user to voluntarily interact with the environment. MUNDUS target pathologies are high-level spinal cord injury (SCI) and neurodegenerative and genetic neuromuscular diseases, such as amyotrophic lateral sclerosis, Friedreich ataxia, and multiple sclerosis (MS). The system can be alternatively driven by residual voluntary muscular activation, head/eye motion, and brain signals. MUNDUS modularly combines an antigravity lightweight and non-cumbersome exoskeleton, closed-loop controlled Neuromuscular Electrical Stimulation for arm and hand motion, and potentially a motorized hand orthosis, for grasping interactive objects. The definition of the requirements and of the interaction tasks were designed by a focus group with experts and a questionnaire with 36 potential end-users. The functionality of all modules has been successfully demonstrated. User's intention was detected with a 100% success. Averaging all subjects and tasks, the minimum evaluation score obtained was 1.13 ± 0.99 for the release of the handle during the drinking task, whilst all the other sub-actions achieved a mean value above 1.6. All users, but one, subjectively perceived the usefulness of the assistance and could easily control the system. Donning time ranged from 6 to 65 minutes, scaled on the configuration complexity. The MUNDUS platform provides functional assistance to daily life activities; the modules integration depends on the user's need, the functionality of the system have been demonstrated for all the possible configurations, and preliminary assessment of usability and acceptance is promising.

Complex interactions between diapirs and 4-D subduction driven mantle wedge circulation.

NASA Astrophysics Data System (ADS)

Sylvia, R. T.; Kincaid, C. R.

2015-12-01

Analogue laboratory experiments generate 4-D flow of mantle wedge fluid and capture the evolution of buoyant mesoscale diapirs. The mantle is modeled with viscous glucose syrup with an Arrhenius type temperature dependent viscosity. To characterize diapir evolution we experiment with a variety of fluids injected from multiple point sources. Diapirs interact with kinematically induced flow fields forced by subducting plate motions replicating a range of styles observed in dynamic subduction models (e.g., rollback, steepening, gaps). Data is collected using high definition timelapse photography and quantified using image velocimetry techniques. While many studies assume direct vertical connections between the volcanic arc and the deeper mantle source region, our experiments demonstrate the difficulty of creating near vertical conduits. Results highlight extreme curvature of diapir rise paths. Trench-normal deflection occurs as diapirs are advected downward away from the trench before ascending into wedge apex directed return flow. Trench parallel deflections up to 75% of trench length are seen in all cases, exacerbated by complex geometry and rollback motion. Interdiapir interaction is also important; upwellings with similar trajectory coalesce and rapidly accelerate. Moreover, we observe a new mode of interaction whereby recycled diapir material is drawn down along the slab surface and then initiates rapid fluid migration updip along the slab-wedge interface. Variability in trajectory and residence time leads to complex petrologic inferences. Material from disparate source regions can surface at the same location, mix in the wedge, or become fully entrained in creeping flow adding heterogeneity to the mantle. Active diapirism or any other vertical fluid flux mechanism employing rheological weakening lowers viscosity in the recycling mantle wedge affecting both solid and fluid flow characteristics. Many interesting and insightful results have been presented based upon 2-D, steady-state thermal and flow regimes. We reiterate the importance of 4-D time evolution in subduction models. Analogue experiments allow added feedbacks and complexity improving intuition and providing insight for further investigation.

Pair mobility functions for rigid spheres in concentrated colloidal dispersions: Stresslet and straining motion couplings

NASA Astrophysics Data System (ADS)

Su, Yu; Swan, James W.; Zia, Roseanna N.

2017-03-01

Accurate modeling of particle interactions arising from hydrodynamic, entropic, and other microscopic forces is essential to understanding and predicting particle motion and suspension behavior in complex and biological fluids. The long-range nature of hydrodynamic interactions can be particularly challenging to capture. In dilute dispersions, pair-level interactions are sufficient and can be modeled in detail by analytical relations derived by Jeffrey and Onishi [J. Fluid Mech. 139, 261-290 (1984)] and Jeffrey [Phys. Fluids A 4, 16-29 (1992)]. In more concentrated dispersions, analytical modeling of many-body hydrodynamic interactions quickly becomes intractable, leading to the development of simplified models. These include mean-field approaches that smear out particle-scale structure and essentially assume that long-range hydrodynamic interactions are screened by crowding, as particle mobility decays at high concentrations. Toward the development of an accurate and simplified model for the hydrodynamic interactions in concentrated suspensions, we recently computed a set of effective pair of hydrodynamic functions coupling particle motion to a hydrodynamic force and torque at volume fractions up to 50% utilizing accelerated Stokesian dynamics and a fast stochastic sampling technique [Zia et al., J. Chem. Phys. 143, 224901 (2015)]. We showed that the hydrodynamic mobility in suspensions of colloidal spheres is not screened, and the power law decay of the hydrodynamic functions persists at all concentrations studied. In the present work, we extend these mobility functions to include the couplings of particle motion and straining flow to the hydrodynamic stresslet. The couplings computed in these two articles constitute a set of orthogonal coupling functions that can be utilized to compute equilibrium properties in suspensions at arbitrary concentration and are readily applied to solve many-body hydrodynamic interactions analytically.

Slow-motion scattering and coalescence of maximally charged black holes

NASA Technical Reports Server (NTRS)

Ferrell, Robert C.; Eardley, Douglas M.

1987-01-01

Systems consisting of several maximally charged, nonrotating black holes ('Reissner-Nordstrom' black holes) interacting with one another are studied. An effective action for the system in the slow-motion, fully strong-field regime is presented. An exact calculation of black-hole-black-hole scattering and coalescence in the slow-motion (but strong-field) limit is given.

Trajectory of Charged Particle in Combined Electric and Magnetic Fields Using Interactive Spreadsheets

ERIC Educational Resources Information Center

Tambade, Popat S.

2011-01-01

The objective of this article is to graphically illustrate to the students the physical phenomenon of motion of charged particle under the action of simultaneous electric and magnetic fields by simulating particle motion on a computer. Differential equations of motions are solved analytically and path of particle in three-dimensional space are…

The proximal-to-distal sequence in upper-limb motions on multiple levels and time scales.

PubMed

Serrien, Ben; Baeyens, Jean-Pierre

2017-10-01

The proximal-to-distal sequence is a phenomenon that can be observed in a large variety of motions of the upper limbs in both humans and other mammals. The mechanisms behind this sequence are not completely understood and motor control theories able to explain this phenomenon are currently incomplete. The aim of this narrative review is to take a theoretical constraints-led approach to the proximal-to-distal sequence and provide a broad multidisciplinary overview of relevant literature. This sequence exists at multiple levels (brain, spine, muscles, kinetics and kinematics) and on multiple time scales (motion, motor learning and development, growth and possibly even evolution). We hypothesize that the proximodistal spatiotemporal direction on each time scale and level provides part of the organismic constraints that guide the dynamics at the other levels and time scales. The constraint-led approach in this review may serve as a first onset towards integration of evidence and a framework for further experimentation to reveal the dynamics of the proximal-to-distal sequence. Copyright © 2017 Elsevier B.V. All rights reserved.

Multi-camera sensor system for 3D segmentation and localization of multiple mobile robots.

PubMed

Losada, Cristina; Mazo, Manuel; Palazuelos, Sira; Pizarro, Daniel; Marrón, Marta

2010-01-01

This paper presents a method for obtaining the motion segmentation and 3D localization of multiple mobile robots in an intelligent space using a multi-camera sensor system. The set of calibrated and synchronized cameras are placed in fixed positions within the environment (intelligent space). The proposed algorithm for motion segmentation and 3D localization is based on the minimization of an objective function. This function includes information from all the cameras, and it does not rely on previous knowledge or invasive landmarks on board the robots. The proposed objective function depends on three groups of variables: the segmentation boundaries, the motion parameters and the depth. For the objective function minimization, we use a greedy iterative algorithm with three steps that, after initialization of segmentation boundaries and depth, are repeated until convergence.

Neurons compute internal models of the physical laws of motion.

PubMed

Angelaki, Dora E; Shaikh, Aasef G; Green, Andrea M; Dickman, J David

2004-07-29

A critical step in self-motion perception and spatial awareness is the integration of motion cues from multiple sensory organs that individually do not provide an accurate representation of the physical world. One of the best-studied sensory ambiguities is found in visual processing, and arises because of the inherent uncertainty in detecting the motion direction of an untextured contour moving within a small aperture. A similar sensory ambiguity arises in identifying the actual motion associated with linear accelerations sensed by the otolith organs in the inner ear. These internal linear accelerometers respond identically during translational motion (for example, running forward) and gravitational accelerations experienced as we reorient the head relative to gravity (that is, head tilt). Using new stimulus combinations, we identify here cerebellar and brainstem motion-sensitive neurons that compute a solution to the inertial motion detection problem. We show that the firing rates of these populations of neurons reflect the computations necessary to construct an internal model representation of the physical equations of motion.

Treatment planning with intensity modulated particle therapy for multiple targets in stage IV non-small cell lung cancer

NASA Astrophysics Data System (ADS)

Anderle, Kristjan; Stroom, Joep; Vieira, Sandra; Pimentel, Nuno; Greco, Carlo; Durante, Marco; Graeff, Christian

2018-01-01

Intensity modulated particle therapy (IMPT) can produce highly conformal plans, but is limited in advanced lung cancer patients with multiple lesions due to motion and planning complexity. A 4D IMPT optimization including all motion states was expanded to include multiple targets, where each target (isocenter) is designated to specific field(s). Furthermore, to achieve stereotactic treatment planning objectives, target and OAR weights plus objective doses were automatically iteratively adapted. Finally, 4D doses were calculated for different motion scenarios. The results from our algorithm were compared to clinical stereotactic body radiation treatment (SBRT) plans. The study included eight patients with 24 lesions in total. Intended dose regimen for SBRT was 24 Gy in one fraction, but lower fractionated doses had to be delivered in three cases due to OAR constraints or failed plan quality assurance. The resulting IMPT treatment plans had no significant difference in target coverage compared to SBRT treatment plans. Average maximum point dose and dose to specific volume in OARs were on average 65% and 22% smaller with IMPT. IMPT could also deliver 24 Gy in one fraction in a patient where SBRT was limited due to the OAR vicinity. The developed algorithm shows the potential of IMPT in treatment of multiple moving targets in a complex geometry.

Recovery of biological motion perception and network plasticity after cerebellar tumor removal.

PubMed

Sokolov, Arseny A; Erb, Michael; Grodd, Wolfgang; Tatagiba, Marcos S; Frackowiak, Richard S J; Pavlova, Marina A

2014-10-01

Visual perception of body motion is vital for everyday activities such as social interaction, motor learning or car driving. Tumors to the left lateral cerebellum impair visual perception of body motion. However, compensatory potential after cerebellar damage and underlying neural mechanisms remain unknown. In the present study, visual sensitivity to point-light body motion was psychophysically assessed in patient SL with dysplastic gangliocytoma (Lhermitte-Duclos disease) to the left cerebellum before and after neurosurgery, and in a group of healthy matched controls. Brain activity during processing of body motion was assessed by functional magnetic resonance imaging (MRI). Alterations in underlying cerebro-cerebellar circuitry were studied by psychophysiological interaction (PPI) analysis. Visual sensitivity to body motion in patient SL before neurosurgery was substantially lower than in controls, with significant improvement after neurosurgery. Functional MRI in patient SL revealed a similar pattern of cerebellar activation during biological motion processing as in healthy participants, but located more medially, in the left cerebellar lobules III and IX. As in normalcy, PPI analysis showed cerebellar communication with a region in the superior temporal sulcus, but located more anteriorly. The findings demonstrate a potential for recovery of visual body motion processing after cerebellar damage, likely mediated by topographic shifts within the corresponding cerebro-cerebellar circuitry induced by cerebellar reorganization. The outcome is of importance for further understanding of cerebellar plasticity and neural circuits underpinning visual social cognition.

Decoding conjunctions of direction-of-motion and binocular disparity from human visual cortex.

PubMed

Seymour, Kiley J; Clifford, Colin W G

2012-05-01

Motion and binocular disparity are two features in our environment that share a common correspondence problem. Decades of psychophysical research dedicated to understanding stereopsis suggest that these features interact early in human visual processing to disambiguate depth. Single-unit recordings in the monkey also provide evidence for the joint encoding of motion and disparity across much of the dorsal visual stream. Here, we used functional MRI and multivariate pattern analysis to examine where in the human brain conjunctions of motion and disparity are encoded. Subjects sequentially viewed two stimuli that could be distinguished only by their conjunctions of motion and disparity. Specifically, each stimulus contained the same feature information (leftward and rightward motion and crossed and uncrossed disparity) but differed exclusively in the way these features were paired. Our results revealed that a linear classifier could accurately decode which stimulus a subject was viewing based on voxel activation patterns throughout the dorsal visual areas and as early as V2. This decoding success was conditional on some voxels being individually sensitive to the unique conjunctions comprising each stimulus, thus a classifier could not rely on independent information about motion and binocular disparity to distinguish these conjunctions. This study expands on evidence that disparity and motion interact at many levels of human visual processing, particularly within the dorsal stream. It also lends support to the idea that stereopsis is subserved by early mechanisms also tuned to direction of motion.

Performance variation due to stiffness in a tuna-inspired flexible foil model.

PubMed

Rosic, Mariel-Luisa N; Thornycroft, Patrick J M; Feilich, Kara L; Lucas, Kelsey N; Lauder, George V

2017-01-17

Tuna are fast, economical swimmers in part due to their stiff, high aspect ratio caudal fins and streamlined bodies. Previous studies using passive caudal fin models have suggested that while high aspect ratio tail shapes such as a tuna's generally perform well, tail performance cannot be determined from shape alone. In this study, we analyzed the swimming performance of tuna-tail-shaped hydrofoils of a wide range of stiffnesses, heave amplitudes, and frequencies to determine how stiffness and kinematics affect multiple swimming performance parameters for a single foil shape. We then compared the foil models' kinematics with published data from a live swimming tuna to determine how well the hydrofoil models could mimic fish kinematics. Foil kinematics over a wide range of motion programs generally showed a minimum lateral displacement at the narrowest part of the foil, and, immediately anterior to that, a local area of large lateral body displacement. These two kinematic patterns may enhance thrust in foils of intermediate stiffness. Stiffness and kinematics exhibited subtle interacting effects on hydrodynamic efficiency, with no one stiffness maximizing both thrust and efficiency. Foils of intermediate stiffnesses typically had the greatest coefficients of thrust at the highest heave amplitudes and frequencies. The comparison of foil kinematics with tuna kinematics showed that tuna motion is better approximated by a zero angle of attack foil motion program than by programs that do not incorporate pitch. These results indicate that open questions in biomechanics may be well served by foil models, given appropriate choice of model characteristics and control programs. Accurate replication of biological movements will require refinement of motion control programs and physical models, including the creation of models of variable stiffness.

Interactive cervical motion kinematics: sensitivity, specificity and clinically significant values for identifying kinematic impairments in patients with chronic neck pain.

PubMed

Sarig Bahat, Hilla; Chen, Xiaoqi; Reznik, David; Kodesh, Einat; Treleaven, Julia

2015-04-01

Chronic neck pain has been consistently shown to be associated with impaired kinematic control including reduced range, velocity and smoothness of cervical motion, that seem relevant to daily function as in quick neck motion in response to surrounding stimuli. The objectives of this study were: to compare interactive cervical kinematics in patients with neck pain and controls; to explore the new measures of cervical motion accuracy; and to find the sensitivity, specificity, and optimal cutoff values for defining impaired kinematics in those with neck pain. In this cross-section study, 33 patients with chronic neck pain and 22 asymptomatic controls were assessed for their cervical kinematic control using interactive virtual reality hardware and customized software utilizing a head mounted display with built-in head tracking. Outcome measures included peak and mean velocity, smoothness (represented by number of velocity peaks (NVP)), symmetry (represented by time to peak velocity percentage (TTPP)), and accuracy of cervical motion. Results demonstrated significant and strong effect-size differences in peak and mean velocities, NVP and TTPP in all directions excluding TTPP in left rotation, and good effect-size group differences in 5/8 accuracy measures. Regression results emphasized the high clinical value of neck motion velocity, with very high sensitivity and specificity (85%-100%), followed by motion smoothness, symmetry and accuracy. These finding suggest cervical kinematics should be evaluated clinically, and screened by the provided cut off values for identification of relevant impairments in those with neck pain. Such identification of presence or absence of kinematic impairments may direct treatment strategies and additional evaluation when needed. Copyright © 2014 Elsevier Ltd. All rights reserved.

Brightness-compensated 3-D optical flow algorithm for monitoring cochlear motion patterns

NASA Astrophysics Data System (ADS)

von Tiedemann, Miriam; Fridberger, Anders; Ulfendahl, Mats; de Monvel, Jacques Boutet

2010-09-01

A method for three-dimensional motion analysis designed for live cell imaging by fluorescence confocal microscopy is described. The approach is based on optical flow computation and takes into account brightness variations in the image scene that are not due to motion, such as photobleaching or fluorescence variations that may reflect changes in cellular physiology. The 3-D optical flow algorithm allowed almost perfect motion estimation on noise-free artificial sequences, and performed with a relative error of <10% on noisy images typical of real experiments. The method was applied to a series of 3-D confocal image stacks from an in vitro preparation of the guinea pig cochlea. The complex motions caused by slow pressure changes in the cochlear compartments were quantified. At the surface of the hearing organ, the largest motion component was the transverse one (normal to the surface), but significant radial and longitudinal displacements were also present. The outer hair cell displayed larger radial motion at their basolateral membrane than at their apical surface. These movements reflect mechanical interactions between different cellular structures, which may be important for communicating sound-evoked vibrations to the sensory cells. A better understanding of these interactions is important for testing realistic models of cochlear mechanics.

Brightness-compensated 3-D optical flow algorithm for monitoring cochlear motion patterns.

PubMed

von Tiedemann, Miriam; Fridberger, Anders; Ulfendahl, Mats; de Monvel, Jacques Boutet

2010-01-01

A method for three-dimensional motion analysis designed for live cell imaging by fluorescence confocal microscopy is described. The approach is based on optical flow computation and takes into account brightness variations in the image scene that are not due to motion, such as photobleaching or fluorescence variations that may reflect changes in cellular physiology. The 3-D optical flow algorithm allowed almost perfect motion estimation on noise-free artificial sequences, and performed with a relative error of <10% on noisy images typical of real experiments. The method was applied to a series of 3-D confocal image stacks from an in vitro preparation of the guinea pig cochlea. The complex motions caused by slow pressure changes in the cochlear compartments were quantified. At the surface of the hearing organ, the largest motion component was the transverse one (normal to the surface), but significant radial and longitudinal displacements were also present. The outer hair cell displayed larger radial motion at their basolateral membrane than at their apical surface. These movements reflect mechanical interactions between different cellular structures, which may be important for communicating sound-evoked vibrations to the sensory cells. A better understanding of these interactions is important for testing realistic models of cochlear mechanics.

Investigating the effect of poly-l-lactic acid nanoparticles carrying hypericin on the flow-biased diffusive motion of HeLa cell organelles.

PubMed

Penjweini, Rozhin; Deville, Sarah; Haji Maghsoudi, Omid; Notelaers, Kristof; Ethirajan, Anitha; Ameloot, Marcel

2017-07-19

In this study, we investigate in human cervical epithelial HeLa cells the intracellular dynamics and the mutual interaction with the organelles of the poly-l-lactic acid nanoparticles (PLLA NPs) carrying the naturally occurring hydrophobic photosensitizer hypericin. Temporal and spatiotemporal image correlation spectroscopy was used for the assessment of the intracellular diffusion and directed motion of the nanocarriers by tracking the hypericin fluorescence. Using image cross-correlation spectroscopy and specific fluorescent labelling of endosomes, lysosomes and mitochondria, the NPs dynamics in association with the cell organelles was studied. Static colocalization experiments were interpreted according to the Manders' overlap coefficient. Nanoparticles associate with a small fraction of the whole-organelle population. The organelles moving with NPs exhibit higher directed motion compared to those moving without them. The rate of the directed motion drops substantially after the application of nocodazole. The random component of the organelle motions is not influenced by the NPs. Image correlation and cross-correlation spectroscopy are most appropriate to unravel the motion of the PLLA nanocarrier and to demonstrate that the rate of the directed motion of organelles is influenced by their interaction with the nanocarriers. Not all PLLA-hypericin NPs are associated with organelles. © 2017 Royal Pharmaceutical Society.

Motion of spin label side chains in cellular retinol-binding protein: correlation with structure and nearest-neighbor interactions in an antiparallel beta-sheet.

PubMed

Lietzow, Michael A; Hubbell, Wayne L

2004-03-23

A goal in the development of site-directed spin labeling in proteins is to correlate the motion of a nitroxide side chain with local structure, interactions, and dynamics. Significant progress toward this goal has been made using alpha-helical proteins of known structure, and the present study is the first step in a similar exploration of a beta-sheet protein, cellular retinol-binding protein (CRBP). Nitroxide side chains were introduced along both interior and edge strands. At sites in interior strands, the side-chain motion is strongly influenced by interactions with side chains of neighboring strands, giving rise to a rich variety of dynamic modes (weakly ordered, strongly ordered, immobilized) and complex electron paramagnetic resonance spectra that are modulated by strand twist. The interactions giving rise to the dynamic modes are explored using mutagenesis, and the results demonstrate the particular importance of the non-hydrogen-bonded neighbor residue in giving rise to highly ordered states. Along edge strands of the beta-sheet, the motion of the side chain is simple and weakly ordered, resembling that at solvent-exposed surfaces of an alpha-helix. A simple working model is proposed that can account for the wide variety of dynamic modes encountered. Collectively, the results suggest that the nitroxide side chain is an effective probe of side-chain interactions, and that site-directed spin labeling should be a powerful means of monitoring conformational changes that involve changes in beta-sheet topology.

Pilot study on real-time motion detection in UAS video data by human observer and image exploitation algorithm

NASA Astrophysics Data System (ADS)

Hild, Jutta; Krüger, Wolfgang; Brüstle, Stefan; Trantelle, Patrick; Unmüßig, Gabriel; Voit, Michael; Heinze, Norbert; Peinsipp-Byma, Elisabeth; Beyerer, Jürgen

2017-05-01

Real-time motion video analysis is a challenging and exhausting task for the human observer, particularly in safety and security critical domains. Hence, customized video analysis systems providing functions for the analysis of subtasks like motion detection or target tracking are welcome. While such automated algorithms relieve the human operators from performing basic subtasks, they impose additional interaction duties on them. Prior work shows that, e.g., for interaction with target tracking algorithms, a gaze-enhanced user interface is beneficial. In this contribution, we present an investigation on interaction with an independent motion detection (IDM) algorithm. Besides identifying an appropriate interaction technique for the user interface - again, we compare gaze-based and traditional mouse-based interaction - we focus on the benefit an IDM algorithm might provide for an UAS video analyst. In a pilot study, we exposed ten subjects to the task of moving target detection in UAS video data twice, once performing with automatic support, once performing without it. We compare the two conditions considering performance in terms of effectiveness (correct target selections). Additionally, we report perceived workload (measured using the NASA-TLX questionnaire) and user satisfaction (measured using the ISO 9241-411 questionnaire). The results show that a combination of gaze input and automated IDM algorithm provides valuable support for the human observer, increasing the number of correct target selections up to 62% and reducing workload at the same time.

Direct numerical simulation of shockwave and turbulent boundary layer interactions

NASA Astrophysics Data System (ADS)

Wu, Minwei

Direct numerical simulations (DNS) of a shockwave/turbulent boundary layer interaction (STBLI) at Mach number 3 and Reynolds number based on the momentum thickness of 2300 are performed. A 4th-order accurate, bandwidth-optimized weighted-essentially-non-oscillatory (WENO) scheme is used and the method is found to be too dissipative for the STBLI simulation due to the over-adaptation properties of this original WENO scheme. In turn, a relative limiter is introduced to mitigate the problem. Tests on the Shu-Osher problem show that the modified WENO scheme decreases the numerical dissipation significantly. By utilizing a combination of the relative limiter and the absolute limiter described by Jiang & Shu [32], the DNS results are improved further. The DNS data agree well with the reference experiments of Bookey et al. [10] in the size of the separation bubble, the separation and reattachment point, the mean wall-pressure distribution, and the velocity profiles both upstream and downstream of the interaction region. The DNS data show that velocity profiles change dramatically along the streamwise direction. Downstream of the interaction, the velocity profiles show a characteristic "dip" in the logarithmic region, as shown by the experiments of Smits & Muck [66] at much higher Reynolds number. In the separation region, the velocity profiles are found to resemble those of a laminar flow, yet the flow does not fully relaminarize. The mass-flux turbulence intensity is amplified by a factor of about 5 throughout the interaction, which is consistent with that found in higher Reynolds experiments of Selig et al. [52]. All Reynolds stress components are greatly amplified by the interaction. Assuming that the ow is still two dimensional downstream of the interaction, the components rhou'u', rhov'v', rho w'w', and rho u'w' are amplified by factors of 6, 6, 12, and 24, respectively, where u is the streamwise and w is the wall-normal velocity. However, analyses of the turbulence structure show that the ow is not uniform in the spanwise direction downstream of the interaction. A pair of counter-rotating vortices is observed in streamwise-wall-normal planes in the mean ow downstream of the ramp corner. Taking the three-dimensionality into account, the amplification factors of the Reynolds stresses are greatly decreased. The component rhou'w' is amplified by a factor of about 10, which is comparable to that found in the experiments of Smits & Muck [66]. Strong Reynolds analogy (SRA) relations are also studied using the DNS data. The SRA is found to hold in the incoming boundary layer of the DNS. However, inside and downstream of the interaction region, the SRA relations are not satisfied. From the DNS analyses, the shock motion is characterized by a low frequency component (of order 0.01Uinfinity/delta). In addition, the motion of the shock is found to have two aspects: a spanwise wrinkling motion and a streamwise oscillatory motion. The spanwise wrinkling is observed to be a local feature with high frequencies (of order Uinfinity /delta). Two-point correlations reveal that the spanwise wrinkling is closely related to the low momentum motions in the incoming boundary layer as they convect through the shock. The low frequency shock motion is found to be a streamwise oscillation motion. Conditional statistics show that there is no significant difference in the mean properties of the incoming boundary layer when the shock is at an upstream or downstream location. However, analyses of the unsteadiness of the separation bubble reveal that the low frequency shock motion is driven by the downstream flow.

Evaluating Suit Fit Using Performance Degradation

NASA Technical Reports Server (NTRS)

Margerum, Sarah E.; Cowley, Matthew; Harvill, Lauren; Benson, Elizabeth; Rajulu, Sudhakar

2012-01-01

The Mark III planetary technology demonstrator space suit can be tailored to an individual by swapping the modular components of the suit, such as the arms, legs, and gloves, as well as adding or removing sizing inserts in key areas. A method was sought to identify the transition from an ideal suit fit to a bad fit and how to quantify this breakdown using a metric of mobility-based human performance data. To this end, the degradation of the range of motion of the elbow and wrist of the suit as a function of suit sizing modifications was investigated to attempt to improve suit fit. The sizing range tested spanned optimal and poor fit and was adjusted incrementally in order to compare each joint angle across five different sizing configurations. Suited range of motion data were collected using a motion capture system for nine isolated and functional tasks utilizing the elbow and wrist joints. A total of four subjects were tested with motions involving both arms simultaneously as well as the right arm by itself. Findings indicated that no single joint drives the performance of the arm as a function of suit size; instead it is based on the interaction of multiple joints along a limb. To determine a size adjustment range where an individual can operate the suit at an acceptable level, a performance detriment limit was set. This user-selected limit reveals the task-dependent tolerance of the suit fit around optimal size. For example, the isolated joint motion indicated that the suit can deviate from optimal by as little as -0.6 in to -2.6 in before experiencing a 10% performance drop in the wrist or elbow joint. The study identified a preliminary method to quantify the impact of size on performance and developed a new way to gauge tolerances around optimal size.

Multi-modal vibration amplitudes of taut inclined cables due to direct and/or parametric excitation

NASA Astrophysics Data System (ADS)

Macdonald, J. H. G.

2016-02-01

Cables are often prone to potentially damaging large amplitude vibrations. The dynamic excitation may be from external loading or motion of the cable ends, the latter including direct excitation, normally from components of end motion transverse to the cable, and parametric excitation induced by axial components of end motion causing dynamic tension variations. Geometric nonlinearity can be important, causing stiffening behaviour and nonlinear modal coupling. Previous analyses of the vibrations, often neglecting sag, have generally dealt with direct and parametric excitation separately or have reverted to numerical solutions of the responses. Here a nonlinear cable model is adopted, applicable to taut cables such as on cable-stayed bridges, that allows for cable inclination, small sag (such that the vibration modes are similar to those of a taut string), multiple modes in both planes and end motion and/or external forcing close to any natural frequency. Based on the method of scaling and averaging it is found that, for sinusoidal inputs and positive damping, non-zero steady state responses can only occur in the modes in each plane with natural frequencies close to the excitation frequency and those with natural frequencies close to half this frequency. Analytical solutions, in the form of non-dimensional polynomial equations, are derived for the steady state vibration amplitudes in up to three modes simultaneously: the directly excited mode, the corresponding nonlinearly coupled mode in the orthogonal plane and a parametrically excited mode with half the natural frequency. The stability of the solutions is also identified. The outputs of the equations are consistent with previous results, where available. Example results from the analytical solutions are presented for a typical inclined bridge cable subject to vertical excitation of the lower end, and they are validated by numerical integration of the equations of motion and against some previous experimental results. It is shown that the modal interactions and sag (although very small) affect the responses significantly.

Independent motion detection with a rival penalized adaptive particle filter

NASA Astrophysics Data System (ADS)

Becker, Stefan; Hübner, Wolfgang; Arens, Michael

2014-10-01

Aggregation of pixel based motion detection into regions of interest, which include views of single moving objects in a scene is an essential pre-processing step in many vision systems. Motion events of this type provide significant information about the object type or build the basis for action recognition. Further, motion is an essential saliency measure, which is able to effectively support high level image analysis. When applied to static cameras, background subtraction methods achieve good results. On the other hand, motion aggregation on freely moving cameras is still a widely unsolved problem. The image flow, measured on a freely moving camera is the result from two major motion types. First the ego-motion of the camera and second object motion, that is independent from the camera motion. When capturing a scene with a camera these two motion types are adverse blended together. In this paper, we propose an approach to detect multiple moving objects from a mobile monocular camera system in an outdoor environment. The overall processing pipeline consists of a fast ego-motion compensation algorithm in the preprocessing stage. Real-time performance is achieved by using a sparse optical flow algorithm as an initial processing stage and a densely applied probabilistic filter in the post-processing stage. Thereby, we follow the idea proposed by Jung and Sukhatme. Normalized intensity differences originating from a sequence of ego-motion compensated difference images represent the probability of moving objects. Noise and registration artefacts are filtered out, using a Bayesian formulation. The resulting a posteriori distribution is located on image regions, showing strong amplitudes in the difference image which are in accordance with the motion prediction. In order to effectively estimate the a posteriori distribution, a particle filter is used. In addition to the fast ego-motion compensation, the main contribution of this paper is the design of the probabilistic filter for real-time detection and tracking of independently moving objects. The proposed approach introduces a competition scheme between particles in order to ensure an improved multi-modality. Further, the filter design helps to generate a particle distribution which is homogenous even in the presence of multiple targets showing non-rigid motion patterns. The effectiveness of the method is shown on exemplary outdoor sequences.

Reaching the boundary between stellar kinematic groups and very wide binaries. III. Sixteen new stars and eight new wide systems in the β Pictoris moving group

NASA Astrophysics Data System (ADS)

Alonso-Floriano, F. J.; Caballero, J. A.; Cortés-Contreras, M.; Solano, E.; Montes, D.

2015-11-01

Aims: We look for common proper motion companions to stars of the nearby young β Pictoris moving group. Methods: First, we compiled a list of 185 β Pictoris members and candidate members from 35 representative works. Next, we used the Aladin and STILTS virtual observatory tools and the PPMXL proper motion and Washington Double Star catalogues to look for companion candidates. The resulting potential companions were subjects of a dedicated astro-photometric follow-up using public data from all-sky surveys. After discarding 67 sources by proper motion and 31 by colour-magnitude diagrams, we obtained a final list of 36 common proper motion systems. The binding energy of two of them is perhaps too small to be considered physically bound. Results: Of the 36 pairs and multiple systems, eight are new, 16 have only one stellar component previously classified as a β Pictoris member, and three have secondaries at or below the hydrogen-burning limit. Sixteen stars are reported here for the first time as moving group members. The unexpected large number of high-order multiple systems, 12 triples and two quadruples among 36 systems, may suggest a biased list of members towards close binaries or an increment of the high-order-multiple fraction for very wide systems.

Feature point based 3D tracking of multiple fish from multi-view images

PubMed Central

Qian, Zhi-Ming

2017-01-01

A feature point based method is proposed for tracking multiple fish in 3D space. First, a simplified representation of the object is realized through construction of two feature point models based on its appearance characteristics. After feature points are classified into occluded and non-occluded types, matching and association are performed, respectively. Finally, the object's motion trajectory in 3D space is obtained through integrating multi-view tracking results. Experimental results show that the proposed method can simultaneously track 3D motion trajectories for up to 10 fish accurately and robustly. PMID:28665966

Feature point based 3D tracking of multiple fish from multi-view images.

PubMed

Qian, Zhi-Ming; Chen, Yan Qiu

2017-01-01

A feature point based method is proposed for tracking multiple fish in 3D space. First, a simplified representation of the object is realized through construction of two feature point models based on its appearance characteristics. After feature points are classified into occluded and non-occluded types, matching and association are performed, respectively. Finally, the object's motion trajectory in 3D space is obtained through integrating multi-view tracking results. Experimental results show that the proposed method can simultaneously track 3D motion trajectories for up to 10 fish accurately and robustly.

Habituation to novel visual vestibular environments with special reference to space flight

NASA Technical Reports Server (NTRS)

Young, L. R.; Kenyon, R. V.; Oman, C. M.

1981-01-01

The etiology of space motion sickness and the underlying physiological mechanisms associated with spatial orientation in a space environment were investigated. Human psychophysical experiments were used as the basis for the research concerning the interaction of visual and vestibular cues in the development of motion sickness. Particular emphasis is placed on the conflict theory in terms of explaining these interactions. Research on the plasticity of the vestibulo-ocular reflex is discussed.

3D force control for robotic-assisted beating heart surgery based on viscoelastic tissue model.

PubMed

Liu, Chao; Moreira, Pedro; Zemiti, Nabil; Poignet, Philippe

2011-01-01

Current cardiac surgery faces the challenging problem of heart beating motion even with the help of mechanical stabilizer which makes delicate operation on the heart surface difficult. Motion compensation methods for robotic-assisted beating heart surgery have been proposed recently in literature, but research on force control for such kind of surgery has hardly been reported. Moreover, the viscoelasticity property of the interaction between organ tissue and robotic instrument further complicates the force control design which is much easier in other applications by assuming the interaction model to be elastic (industry, stiff object manipulation, etc.). In this work, we present a three-dimensional force control method for robotic-assisted beating heart surgery taking into consideration of the viscoelastic interaction property. Performance studies based on our D2M2 robot and 3D heart beating motion information obtained through Da Vinci™ system are provided.

The effects of bound state motion on macromolecular diffusion

NASA Astrophysics Data System (ADS)

Hough, Loren; Stefferson, Michael; Norris, Samantha; Maguire, Laura; Vernerey, Franck; Betterton, Meredith

The diffusion of macromolecules is modified in crowded environments by both inert obstacles and interaction sites. Molecules are generally slowed in their movement inducing transient anomalous subdiffusion. Obstacles also modify the kinetics and equilibrium behavior of interaction between mobile proteins. In some biophysical contexts, bound molecules can still experience mobility, for example transcription factors sliding along DNA, membrane proteins with some entry and diffusion within lipid domains, or proteins that can enter into non-membrane bound compartments such as the nucleolus. We used lattice and continuum models to study the diffusive behavior of tracer particles which bind to obstacles and can diffuse within them. We show that binding significantly alters the motion of tracers. The type and degree of motion while bound is a key determinant of the tracer mobility. Our work has implications for protein-protein movement and interactions within living cells, including those involving intrinsically disordered proteins.

Daphnia swarms: from single agent dynamics to collective vortex formation

NASA Astrophysics Data System (ADS)

Ordemann, Anke; Balazsi, Gabor; Caspari, Elizabeth; Moss, Frank

2003-05-01

Swarm theories have become fashionable in theoretical physics over the last decade. They span the range of interactions from individual agents moving in a mean field to coherent collective motions of large agent populations, such as vortex-swarming. But controlled laboratory tests of these theories using real biological agents have been problematic due primarily to poorly known agent-agent interactions (in the case of e.g. bacteria and slime molds) or the large swarm size (e.g. for flocks of birds and schools of fish). Moreover, the entire range of behaviors from single agent interactions to collective vortex motions of the swarm have here-to-fore not been observed with a single animal. We present the results of well defined experiments with the zooplankton Daphnia in light fields showing this range of behaviors. We interpret our results with a theory of the motions of self-propelled agents in a field.

Training of goal directed arm movements with motion interactive video games in children with cerebral palsy - a kinematic evaluation.

PubMed

Sandlund, Marlene; Domellöf, Erik; Grip, Helena; Rönnqvist, Louise; Häger, Charlotte K

2014-10-01

The main aim of this study was to evaluate the quality of goal-directed arm movements in 15 children with cerebral palsy (CP) following four weeks of home-based training with motion interactive video games. A further aim was to investigate the applicability and characteristics of kinematic parameters in a virtual context in comparison to a physical context. Kinematics and kinetics were captured while the children performed arm movements directed towards both virtual and physical targets. The children's movement precision improved, their centre of pressure paths decreased, as did the variability in maximal shoulder angles when reaching for virtual objects. Transfer to a situation with physical targets was mainly indicated by increased movement smoothness. Training with motion interactive games seems to improve arm motor control in children with CP. The results highlight the importance of considering both the context and the task itself when investigating kinematic parameters.

An innovative training program based on virtual reality and treadmill: effects on gait of persons with multiple sclerosis.

PubMed

Peruzzi, Agnese; Zarbo, Ignazio Roberto; Cereatti, Andrea; Della Croce, Ugo; Mirelman, Anat

2017-07-01

In this single blind randomized controlled trial, we examined the effect of a virtual reality-based training on gait of people with multiple sclerosis. Twenty-five individuals with multiple sclerosis with mild to moderate disability were randomly assigned to either the control group (n = 11) or the experimental group (n = 14). The subjects in the control group received treadmill training. Subjects in the experimental group received virtual reality based treadmill training. Clinical measures and gait parameters were evaluated. Subjects in both the groups significantly improved the walking endurance and speed, cadence and stride length, lower limb joint ranges of motion and powers, during single and dual task gait. Moreover, subjects in the experimental group also improved balance, as indicated by the results of the clinical motor tests (p < 0.05). Between-group comparisons revealed that the experimental group improved significantly more than control group in hip range of motion and hip generated power at terminal stance at post-training. Our results support the perceived benefits of training programs that incorporate virtual reality to improve gait measures in individuals with multiple sclerosis. Implication of rehabilitation Gait deficits are common in multiple sclerosis (85%) and worsen during dual task activities. Intensive and progressive treadmill training, with and without virtual reality, is effective on dual task gait in persons with multiple sclerosis. Virtual reality-based treadmill training requiring obstacle negotiation increases the range of motion and the power generated at the hip, consequently allowing longer stride length and, consequently, higher gait speed.

Compressive Video Recovery Using Block Match Multi-Frame Motion Estimation Based on Single Pixel Cameras

PubMed Central

Bi, Sheng; Zeng, Xiao; Tang, Xin; Qin, Shujia; Lai, King Wai Chiu

2016-01-01

Compressive sensing (CS) theory has opened up new paths for the development of signal processing applications. Based on this theory, a novel single pixel camera architecture has been introduced to overcome the current limitations and challenges of traditional focal plane arrays. However, video quality based on this method is limited by existing acquisition and recovery methods, and the method also suffers from being time-consuming. In this paper, a multi-frame motion estimation algorithm is proposed in CS video to enhance the video quality. The proposed algorithm uses multiple frames to implement motion estimation. Experimental results show that using multi-frame motion estimation can improve the quality of recovered videos. To further reduce the motion estimation time, a block match algorithm is used to process motion estimation. Experiments demonstrate that using the block match algorithm can reduce motion estimation time by 30%. PMID:26950127

Survey of Motion Tracking Methods Based on Inertial Sensors: A Focus on Upper Limb Human Motion

PubMed Central

Filippeschi, Alessandro; Schmitz, Norbert; Miezal, Markus; Bleser, Gabriele; Ruffaldi, Emanuele; Stricker, Didier

2017-01-01

Motion tracking based on commercial inertial measurements units (IMUs) has been widely studied in the latter years as it is a cost-effective enabling technology for those applications in which motion tracking based on optical technologies is unsuitable. This measurement method has a high impact in human performance assessment and human-robot interaction. IMU motion tracking systems are indeed self-contained and wearable, allowing for long-lasting tracking of the user motion in situated environments. After a survey on IMU-based human tracking, five techniques for motion reconstruction were selected and compared to reconstruct a human arm motion. IMU based estimation was matched against motion tracking based on the Vicon marker-based motion tracking system considered as ground truth. Results show that all but one of the selected models perform similarly (about 35 mm average position estimation error). PMID:28587178

A kicking simulator to investigate the foot-ball interaction during a rugby place kick.

PubMed

Minnaar, Nick; van den Heever, Dawie J

2015-01-01

Foot-ball interaction is an important aspect in rugby place kicking but has received very little attention in literature. This preliminary study presents an adjustable mechanical kicking simulator used to investigate different foot positions and orientations during the foot-ball interaction on resultant ball motion. It was found that changes in foot position and orientation during ball contact can have a large influence on ball motion. It is believed that with further research an optimal place-kicking technique can be found to maximize energy transfer to the ball while still maintaining accuracy.

Temporally diffeomorphic cardiac motion estimation from three-dimensional echocardiography by minimization of intensity consistency error.

PubMed

Zhang, Zhijun; Ashraf, Muhammad; Sahn, David J; Song, Xubo

2014-05-01

Quantitative analysis of cardiac motion is important for evaluation of heart function. Three dimensional (3D) echocardiography is among the most frequently used imaging modalities for motion estimation because it is convenient, real-time, low-cost, and nonionizing. However, motion estimation from 3D echocardiographic sequences is still a challenging problem due to low image quality and image corruption by noise and artifacts. The authors have developed a temporally diffeomorphic motion estimation approach in which the velocity field instead of the displacement field was optimized. The optimal velocity field optimizes a novel similarity function, which we call the intensity consistency error, defined as multiple consecutive frames evolving to each time point. The optimization problem is solved by using the steepest descent method. Experiments with simulated datasets, images of anex vivo rabbit phantom, images of in vivo open-chest pig hearts, and healthy human images were used to validate the authors' method. Simulated and real cardiac sequences tests showed that results in the authors' method are more accurate than other competing temporal diffeomorphic methods. Tests with sonomicrometry showed that the tracked crystal positions have good agreement with ground truth and the authors' method has higher accuracy than the temporal diffeomorphic free-form deformation (TDFFD) method. Validation with an open-access human cardiac dataset showed that the authors' method has smaller feature tracking errors than both TDFFD and frame-to-frame methods. The authors proposed a diffeomorphic motion estimation method with temporal smoothness by constraining the velocity field to have maximum local intensity consistency within multiple consecutive frames. The estimated motion using the authors' method has good temporal consistency and is more accurate than other temporally diffeomorphic motion estimation methods.

Interpersonal Coordination of Head Motion in Distressed Couples

PubMed Central

Hammal, Zakia; Cohn, Jeffrey F.; George, David T.

2015-01-01

In automatic emotional expression analysis, head motion has been considered mostly a nuisance variable, something to control when extracting features for action unit or expression detection. As an initial step toward understanding the contribution of head motion to emotion communication, we investigated the interpersonal coordination of rigid head motion in intimate couples with a history of interpersonal violence. Episodes of conflict and non-conflict were elicited in dyadic interaction tasks and validated using linguistic criteria. Head motion parameters were analyzed using Student’s paired t-tests; actor-partner analyses to model mutual influence within couples; and windowed cross-correlation to reveal dynamics of change in direction of influence over time. Partners’ RMS angular displacement for yaw and RMS angular velocity for pitch and yaw each demonstrated strong mutual influence between partners. Partners’ RMS angular displacement for pitch was higher during conflict. In both conflict and non-conflict, head angular displacement and angular velocity for pitch and yaw were strongly correlated, with frequent shifts in lead-lag relationships. The overall amount of coordination between partners’ head movement was more highly correlated during non-conflict compared with conflict interaction. While conflict increased head motion, it served to attenuate interpersonal coordination. PMID:26167256

Dimensionality and integrals of motion of the Trappist-1 planetary system

NASA Astrophysics Data System (ADS)

Floß, Johannes; Rein, Hanno; Brumer, Paul

2018-04-01

The number of isolating integrals of motion of the Trappist-1 system - a late M-dwarf orbited by seven Earth-sized planets - was determined numerically, using an adapted version of the correlation dimension method. It was found that over the investigated time-scales of up to 20 000 years the number of isolating integrals of motion is the same as one would find for a system of seven non-interacting planets - despite the fact that the planets in the Trappist-1 system are strongly interacting. Considering perturbed versions of the Trappist-1 system shows that the system may occupy an atypical part of phase-space with high stability. These findings are consistent with earlier studies.

Computational model for amoeboid motion: Coupling membrane and cytosol dynamics

NASA Astrophysics Data System (ADS)

Moure, Adrian; Gomez, Hector

2016-10-01

A distinguishing feature of amoeboid motion is that the migrating cell undergoes large deformations, caused by the emergence and retraction of actin-rich protrusions, called pseudopods. Here, we propose a cell motility model that represents pseudopod dynamics, as well as its interaction with membrane signaling molecules. The model accounts for internal and external forces, such as protrusion, contraction, adhesion, surface tension, or those arising from cell-obstacle contacts. By coupling the membrane and cytosol interactions we are able to reproduce a realistic picture of amoeboid motion. The model results are in quantitative agreement with experiments and show how cells may take advantage of the geometry of their microenvironment to migrate more efficiently.

Dimensionality and integrals of motion of the Trappist-1 planetary system

NASA Astrophysics Data System (ADS)

Floß, Johannes; Rein, Hanno; Brumer, Paul

2018-07-01

The number of isolating integrals of motion of the Trappist-1 system - a late M-dwarf orbited by seven Earth-sized planets - was determined numerically, using an adapted version of the correlation dimension method. It was found that over the investigated time-scales of up to 20 000 yr the number of isolating integrals of motion is the same as one would find for a system of seven non-interacting planets - despite the fact that the planets in the Trappist-1 system are strongly interacting. Considering perturbed versions of the Trappist-1 system shows that the system may occupy an atypical part of phase-space with high stability. These findings are consistent with earlier studies.

Large Scale Structure From Motion for Autonomous Underwater Vehicle Surveys

DTIC Science & Technology

2004-09-01

Govern the Formation of Multiple Images of a Scene and Some of Their Applications. MIT Press, 2001. [26] 0. Faugeras and S. Maybank . Motion from point...Machine Vision Conference, volume 1, pages 384-393, September 2002. [69] S. Maybank and 0. Faugeras. A theory of self-calibration of a moving camera

The derivative and tangent operators of a motion in Lorentzian space

NASA Astrophysics Data System (ADS)

Durmaz, Olgun; Aktaş, Buşra; Gündoğan, Hali˙t

In this paper, by using Lorentzian matrix multiplication, L-Tangent operator is obtained in Lorentzian space. The L-Tangent operators related with planar, spherical and spatial motion are computed via special matrix groups. L-Tangent operators are related to vectors. Some illustrative examples for applications of L-Tangent operators are also presented.

Mechanical design of NASA Ames Research Center vertical motion simulator

NASA Technical Reports Server (NTRS)

Engelbert, D. F.; Bakke, A. P.; Chargin, M. K.; Vallotton, W. C.

1976-01-01

NASA has designed and is constructing a new flight simulator with large vertical travel. Several aspects of the mechanical design of this Vertical Motion Simulator (VMS) are discussed, including the multiple rack and pinion vertical drive, a pneumatic equilibration system, and the friction-damped rigid link catenaries used as cable supports.

On the first crossing distributions in fractional Brownian motion and the mass function of dark matter haloes

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

Hiotelis, Nicos; Popolo, Antonino Del, E-mail: adelpopolo@oact.inaf.it, E-mail: hiotelis@ipta.demokritos.gr

We construct an integral equation for the first crossing distributions for fractional Brownian motion in the case of a constant barrier and we present an exact analytical solution. Additionally we present first crossing distributions derived by simulating paths from fractional Brownian motion. We compare the results of the analytical solutions with both those of simulations and those of some approximated solutions which have been used in the literature. Finally, we present multiplicity functions for dark matter structures resulting from our analytical approach and we compare with those resulting from N-body simulations. We show that the results of analytical solutions aremore » in good agreement with those of path simulations but differ significantly from those derived from approximated solutions. Additionally, multiplicity functions derived from fractional Brownian motion are poor fits of the those which result from N-body simulations. We also present comparisons with other models which are exist in the literature and we discuss different ways of improving the agreement between analytical results and N-body simulations.« less

Motion correction in periodically-rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) and turboprop MRI.

PubMed

Tamhane, Ashish A; Arfanakis, Konstantinos

2009-07-01

Periodically-rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) and Turboprop MRI are characterized by greatly reduced sensitivity to motion, compared to their predecessors, fast spin-echo (FSE) and gradient and spin-echo (GRASE), respectively. This is due to the inherent self-navigation and motion correction of PROPELLER-based techniques. However, it is unknown how various acquisition parameters that determine k-space sampling affect the accuracy of motion correction in PROPELLER and Turboprop MRI. The goal of this work was to evaluate the accuracy of motion correction in both techniques, to identify an optimal rotation correction approach, and determine acquisition strategies for optimal motion correction. It was demonstrated that blades with multiple lines allow more accurate estimation of motion than blades with fewer lines. Also, it was shown that Turboprop MRI is less sensitive to motion than PROPELLER. Furthermore, it was demonstrated that the number of blades does not significantly affect motion correction. Finally, clinically appropriate acquisition strategies that optimize motion correction are discussed for PROPELLER and Turboprop MRI. (c) 2009 Wiley-Liss, Inc.

Attraction of posture and motion-trajectory elements of conspecific biological motion in medaka fish.

PubMed

Shibai, Atsushi; Arimoto, Tsunehiro; Yoshinaga, Tsukasa; Tsuchizawa, Yuta; Khureltulga, Dashdavaa; Brown, Zuben P; Kakizuka, Taishi; Hosoda, Kazufumi

2018-06-05

Visual recognition of conspecifics is necessary for a wide range of social behaviours in many animals. Medaka (Japanese rice fish), a commonly used model organism, are known to be attracted by the biological motion of conspecifics. However, biological motion is a composite of both body-shape motion and entire-field motion trajectory (i.e., posture or motion-trajectory elements, respectively), and it has not been revealed which element mediates the attractiveness. Here, we show that either posture or motion-trajectory elements alone can attract medaka. We decomposed biological motion of the medaka into the two elements and synthesized visual stimuli that contain both, either, or none of the two elements. We found that medaka were attracted by visual stimuli that contain at least one of the two elements. In the context of other known static visual information regarding the medaka, the potential multiplicity of information regarding conspecific recognition has further accumulated. Our strategy of decomposing biological motion into these partial elements is applicable to other animals, and further studies using this technique will enhance the basic understanding of visual recognition of conspecifics.

Gesture Recognition Based on the Probability Distribution of Arm Trajectories

NASA Astrophysics Data System (ADS)

Wan, Khairunizam; Sawada, Hideyuki

The use of human motions for the interaction between humans and computers is becoming an attractive alternative to verbal media, especially through the visual interpretation of the human body motion. In particular, hand gestures are used as non-verbal media for the humans to communicate with machines that pertain to the use of the human gestures to interact with them. This paper introduces a 3D motion measurement of the human upper body for the purpose of the gesture recognition, which is based on the probability distribution of arm trajectories. In this study, by examining the characteristics of the arm trajectories given by a signer, motion features are selected and classified by using a fuzzy technique. Experimental results show that the use of the features extracted from arm trajectories effectively works on the recognition of dynamic gestures of a human, and gives a good performance to classify various gesture patterns.

Master equation with quantized atomic motion including dipole-dipole interactions

NASA Astrophysics Data System (ADS)

Damanet, François; Braun, Daniel; Martin, John

2016-05-01

We derive a markovian master equation for the internal dynamics of an ensemble of two-level atoms including all effects related to the quantization of their motion. Our equation provides a unifying picture of the consequences of recoil and indistinguishability of atoms beyond the Lamb-Dicke regime on both their dissipative and conservative dynamics, and is relevant for experiments with ultracold trapped atoms. We give general expressions for the decay rates and the dipole-dipole shifts for any motional states, and we find analytical formulas for a number of relevant states (Gaussian states, Fock states and thermal states). In particular, we show that the dipole-dipole interactions and cooperative photon emission can be modulated through the external state of motion. The effects predicted should be experimentally observable with Rydberg atoms. FD would like to thank the F.R.S.-FNRS for financial support. FD is a FRIA Grant holder of the Fonds de la Recherche Scientifique-FNRS.

111 years of Brownian motion.

PubMed

Bian, Xin; Kim, Changho; Karniadakis, George Em

2016-08-14

We consider the Brownian motion of a particle and present a tutorial review over the last 111 years since Einstein's paper in 1905. We describe Einstein's model, Langevin's model and the hydrodynamic models, with increasing sophistication on the hydrodynamic interactions between the particle and the fluid. In recent years, the effects of interfaces on the nearby Brownian motion have been the focus of several investigations. We summarize various results and discuss some of the controversies associated with new findings about the changes in Brownian motion induced by the interface.

Design Definition Study Report. Full Crew Interaction Simulator-Laboratory Model (FCIS-LM) (Device X17B7). Volume II. Requirements.

DTIC Science & Technology

1978-06-01

stimulate at-least three levels of crew function. At the most complex level, visual cues are used to discriminate the presence or activities of...limited to motion on- set cues washed out at subliminal levels.. Because of the cues they provide the driver, gunner, and commander, and the dis...motion, i.e.,which physiological receptors are affected, how they function,and how they may be stimulated by a simulator motion system. I Motion is

Thermally Activated Motion of Sodium Cations in Insulating Parent Low-Silica X Zeolite

NASA Astrophysics Data System (ADS)

Igarashi, Mutsuo; Jeglič, Peter; Mežnaršič, Tadej; Nakano, Takehito; Nozue, Yasuo; Watanabe, Naohiro; Arčon, Denis

2017-07-01

We report a 23Na spin-lattice relaxation rate, T1 - 1, in low-silica X zeolite. T1 - 1 follows multiple BPP-type behavior as a result of thermal motion of sodium cations in insulating material. The estimated lowest activation energy of 15 meV is much lower than 100 meV observed previously for sodium motion in heavily Na-loaded samples and is most likely attributed to short-distance jumps of sodium cations between sites within the same supercage.

Choice-reaction time to visual motion with varied levels of simultaneous rotary motion

NASA Technical Reports Server (NTRS)

Clark, B.; Stewart, J. D.

1974-01-01

Twelve airline pilots were studied to determine the effects of whole-body rotation on choice-reaction time to the horizontal motion of a line on a cathode-ray tube. On each trial, one of five levels of visual acceleration and five corresponding proportions of rotary acceleration were presented simultaneously. Reaction time to the visual motion decreased with increasing levels of visual motion and increased with increasing proportions of rotary acceleration. The results conflict with general theories of facilitation during double stimulation but are consistent with neural-clock model of sensory interaction in choice-reaction time.

Incorporating contact angles in the surface tension force with the ACES interface curvature scheme

NASA Astrophysics Data System (ADS)

Owkes, Mark

2017-11-01

In simulations of gas-liquid flows interacting with solid boundaries, the contact line dynamics effect the interface motion and flow field through the surface tension force. The surface tension force is directly proportional to the interface curvature and the problem of accurately imposing a contact angle must be incorporated into the interface curvature calculation. Many commonly used algorithms to compute interface curvatures (e.g., height function method) require extrapolating the interface, with defined contact angle, into the solid to allow for the calculation of a curvature near a wall. Extrapolating can be an ill-posed problem, especially in three-dimensions or when multiple contact lines are near each other. We have developed an accurate methodology to compute interface curvatures that allows for contact angles to be easily incorporated while avoiding extrapolation and the associated challenges. The method, known as Adjustable Curvature Evaluation Scale (ACES), leverages a least squares fit of a polynomial to points computed on the volume-of-fluid (VOF) representation of the gas-liquid interface. The method is tested by simulating canonical test cases and then applied to simulate the injection and motion of water droplets in a channel (relevant to PEM fuel cells).

Multi-Target Camera Tracking, Hand-off and Display LDRD 158819 Final Report

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

Anderson, Robert J.

2014-10-01

Modern security control rooms gather video and sensor feeds from tens to hundreds of cameras. Advanced camera analytics can detect motion from individual video streams and convert unexpected motion into alarms, but the interpretation of these alarms depends heavily upon human operators. Unfortunately, these operators can be overwhelmed when a large number of events happen simultaneously, or lulled into complacency due to frequent false alarms. This LDRD project has focused on improving video surveillance-based security systems by changing the fundamental focus from the cameras to the targets being tracked. If properly integrated, more cameras shouldn’t lead to more alarms, moremore » monitors, more operators, and increased response latency but instead should lead to better information and more rapid response times. For the course of the LDRD we have been developing algorithms that take live video imagery from multiple video cameras, identify individual moving targets from the background imagery, and then display the results in a single 3D interactive video. In this document we summarize the work in developing this multi-camera, multi-target system, including lessons learned, tools developed, technologies explored, and a description of current capability.« less

Multi-target camera tracking, hand-off and display LDRD 158819 final report

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

Anderson, Robert J.

2014-10-01

Modern security control rooms gather video and sensor feeds from tens to hundreds of cameras. Advanced camera analytics can detect motion from individual video streams and convert unexpected motion into alarms, but the interpretation of these alarms depends heavily upon human operators. Unfortunately, these operators can be overwhelmed when a large number of events happen simultaneously, or lulled into complacency due to frequent false alarms. This LDRD project has focused on improving video surveillance-based security systems by changing the fundamental focus from the cameras to the targets being tracked. If properly integrated, more cameras shouldn't lead to more alarms, moremore » monitors, more operators, and increased response latency but instead should lead to better information and more rapid response times. For the course of the LDRD we have been developing algorithms that take live video imagery from multiple video cameras, identifies individual moving targets from the background imagery, and then displays the results in a single 3D interactive video. In this document we summarize the work in developing this multi-camera, multi-target system, including lessons learned, tools developed, technologies explored, and a description of current capability.« less

"I remember when we stayed still and the computer still made lines": Young children's invented and conventional representations of motion

NASA Astrophysics Data System (ADS)

Kahn, Jason

This dissertation concerns kindergarteners' and second graders' invented representations of motion, their interactions with conventional representations of motion built from the child's movement in front of a motion detector and using real-time graphing tools, and any changes in the invented representations that this interaction brings about. We have known for several decades that advanced learners (high school aged and beyond) struggle with physics concepts of motion and sometimes Cartesian graph-based representations of motion. Little has been known about how younger students approach the same concepts. In this study, eighteen children (10 kindergarteners and eight second graders) completed a three-hour clinical interview spread out evenly over three weeks. In the first and last interviews, the child was asked to produce external representations of movement and interpret conventional distance and time graphs of motion. In the second interview the children interacted with a motion detector and real-time graphing tools in a semi-self-directed format. Qualitative and quantitative results are presented and discussed. Qualitative data shows that children are adroit at representing motion and their productions are systematic and purposeful. Children produce drawings that both give context to the physical environment around them and also redescribe the drawn environment, meaning that they provide a potential audience with information otherwise imperceptible, by making certain implicit aspects more explicit. Second graders quickly appropriate the Cartesian graph during the intervention, though at times misinterpret the meaning associated with slope. Children correctly associate slope with direction, but at times misattribute sign of slope (positive or negative) and its corresponding direction (i.e. some children do not ascribe positive slope with motion away from a point of reference, but toward it). Kindergarteners showed a range of experiences during the intervention, one of the students showed a near mastery in interpretation of a Cartesian graph as a representation of motion, while another vehemently resisted graph as a representation of motion. Quantitative data gives a mechanism for comparing pre- and post-assessment productions. Both kindergarten and second grade students provide richer post-assessment representations, with kindergarteners more likely to include a figurative point of reference in the post-assessment and second graders including more explicit information about speed. The implications of this study are that invented representations of motion are a powerful tool for providing insights into children's thinking. The motion detector and real-time graphing tool can be used as early as kindergarten to help children build resources in their representations of motion; second grade students could find the same benefit and potentially begin to build conventional ideas about graphing and movement.

Real-time prediction of respiratory motion based on a local dynamic model in an augmented space

NASA Astrophysics Data System (ADS)

Hong, S.-M.; Jung, B.-H.; Ruan, D.

2011-03-01

Motion-adaptive radiotherapy aims to deliver ablative radiation dose to the tumor target with minimal normal tissue exposure, by accounting for real-time target movement. In practice, prediction is usually necessary to compensate for system latency induced by measurement, communication and control. This work focuses on predicting respiratory motion, which is most dominant for thoracic and abdominal tumors. We develop and investigate the use of a local dynamic model in an augmented space, motivated by the observation that respiratory movement exhibits a locally circular pattern in a plane augmented with a delayed axis. By including the angular velocity as part of the system state, the proposed dynamic model effectively captures the natural evolution of respiratory motion. The first-order extended Kalman filter is used to propagate and update the state estimate. The target location is predicted by evaluating the local dynamic model equations at the required prediction length. This method is complementary to existing work in that (1) the local circular motion model characterizes 'turning', overcoming the limitation of linear motion models; (2) it uses a natural state representation including the local angular velocity and updates the state estimate systematically, offering explicit physical interpretations; (3) it relies on a parametric model and is much less data-satiate than the typical adaptive semiparametric or nonparametric method. We tested the performance of the proposed method with ten RPM traces, using the normalized root mean squared difference between the predicted value and the retrospective observation as the error metric. Its performance was compared with predictors based on the linear model, the interacting multiple linear models and the kernel density estimator for various combinations of prediction lengths and observation rates. The local dynamic model based approach provides the best performance for short to medium prediction lengths under relatively low observation rate. Sensitivity analysis indicates its robustness toward the choice of parameters. Its simplicity, robustness and low computation cost makes the proposed local dynamic model an attractive tool for real-time prediction with system latencies below 0.4 s.

Real-time prediction of respiratory motion based on a local dynamic model in an augmented space.

PubMed

Hong, S-M; Jung, B-H; Ruan, D

2011-03-21

Motion-adaptive radiotherapy aims to deliver ablative radiation dose to the tumor target with minimal normal tissue exposure, by accounting for real-time target movement. In practice, prediction is usually necessary to compensate for system latency induced by measurement, communication and control. This work focuses on predicting respiratory motion, which is most dominant for thoracic and abdominal tumors. We develop and investigate the use of a local dynamic model in an augmented space, motivated by the observation that respiratory movement exhibits a locally circular pattern in a plane augmented with a delayed axis. By including the angular velocity as part of the system state, the proposed dynamic model effectively captures the natural evolution of respiratory motion. The first-order extended Kalman filter is used to propagate and update the state estimate. The target location is predicted by evaluating the local dynamic model equations at the required prediction length. This method is complementary to existing work in that (1) the local circular motion model characterizes 'turning', overcoming the limitation of linear motion models; (2) it uses a natural state representation including the local angular velocity and updates the state estimate systematically, offering explicit physical interpretations; (3) it relies on a parametric model and is much less data-satiate than the typical adaptive semiparametric or nonparametric method. We tested the performance of the proposed method with ten RPM traces, using the normalized root mean squared difference between the predicted value and the retrospective observation as the error metric. Its performance was compared with predictors based on the linear model, the interacting multiple linear models and the kernel density estimator for various combinations of prediction lengths and observation rates. The local dynamic model based approach provides the best performance for short to medium prediction lengths under relatively low observation rate. Sensitivity analysis indicates its robustness toward the choice of parameters. Its simplicity, robustness and low computation cost makes the proposed local dynamic model an attractive tool for real-time prediction with system latencies below 0.4 s.

Investigation of glucose binding sites on insulin.

PubMed

Zoete, Vincent; Meuwly, Markus; Karplus, Martin

2004-05-15

Possible insulin binding sites for D-glucose have been investigated theoretically by docking and molecular dynamics (MD) simulations. Two different docking programs for small molecules were used; Multiple Copy Simultaneous Search (MCSS) and Solvation Energy for Exhaustive Docking (SEED) programs. The configurations resulting from the MCSS search were evaluated with a scoring function developed to estimate the binding free energy. SEED calculations were performed using various values for the dielectric constant of the solute. It is found that scores emphasizing non-polar interactions gave a preferential binding site in agreement with that inferred from recent fluorescence and NMR NOESY experiments. The calculated binding affinity of -1.4 to -3.5 kcal/mol is within the measured range of -2.0 +/- 0.5 kcal/mol. The validity of the binding site is suggested by the dynamical stability of the bound glucose when examined with MD simulations with explicit solvent. Alternative binding sites were found in the simulations and their relative stabilities were estimated. The motions of the bound glucose during molecular dynamics simulations are correlated with the motions of the insulin side chains that are in contact with it and with larger scale insulin motions. These results raise the question of whether glucose binding to insulin could play a role in its activity. The results establish the complementarity of molecular dynamics simulations and normal mode analyses with the search for binding sites proposed with small molecule docking programs. Copyright 2004 Wiley-Liss, Inc.

Measurement of energy landscape roughness of folded and unfolded proteins

PubMed Central

Milanesi, Lilia; Waltho, Jonathan P.; Hunter, Christopher A.; Shaw, Daniel J.; Beddard, Godfrey S.; Reid, Gavin D.; Dev, Sagarika; Volk, Martin

2012-01-01

The dynamics of protein conformational changes, from protein folding to smaller changes, such as those involved in ligand binding, are governed by the properties of the conformational energy landscape. Different techniques have been used to follow the motion of a protein over this landscape and thus quantify its properties. However, these techniques often are limited to short timescales and low-energy conformations. Here, we describe a general approach that overcomes these limitations. Starting from a nonnative conformation held by an aromatic disulfide bond, we use time-resolved spectroscopy to observe nonequilibrium backbone dynamics over nine orders of magnitude in time, from picoseconds to milliseconds, after photolysis of the disulfide bond. We find that the reencounter probability of residues that initially are in close contact decreases with time following an unusual power law that persists over the full time range and is independent of the primary sequence. Model simulations show that this power law arises from subdiffusional motion, indicating a wide distribution of trapping times in local minima of the energy landscape, and enable us to quantify the roughness of the energy landscape (4–5 kBT). Surprisingly, even under denaturing conditions, the energy landscape remains highly rugged with deep traps (>20 kBT) that result from multiple nonnative interactions and are sufficient for trapping on the millisecond timescale. Finally, we suggest that the subdiffusional motion of the protein backbone found here may promote rapid folding of proteins with low contact order by enhancing contact formation between nearby residues. PMID:23150572

Temporal ventriloquism along the path of apparent motion: speed perception under different spatial grouping principles.

PubMed

Ogulmus, Cansu; Karacaoglu, Merve; Kafaligonul, Hulusi

2018-03-01

The coordination of intramodal perceptual grouping and crossmodal interactions plays a critical role in constructing coherent multisensory percepts. However, the basic principles underlying such coordinating mechanisms still remain unclear. By taking advantage of an illusion called temporal ventriloquism and its influences on perceived speed, we investigated how audiovisual interactions in time are modulated by the spatial grouping principles of vision. In our experiments, we manipulated the spatial grouping principles of proximity, uniform connectedness, and similarity/common fate in apparent motion displays. Observers compared the speed of apparent motions across different sound timing conditions. Our results revealed that the effects of sound timing (i.e., temporal ventriloquism effects) on perceived speed also existed in visual displays containing more than one object and were modulated by different spatial grouping principles. In particular, uniform connectedness was found to modulate these audiovisual interactions in time. The effect of sound timing on perceived speed was smaller when horizontal connecting bars were introduced along the path of apparent motion. When the objects in each apparent motion frame were not connected or connected with vertical bars, the sound timing was more influential compared to the horizontal bar conditions. Overall, our findings here suggest that the effects of sound timing on perceived speed exist in different spatial configurations and can be modulated by certain intramodal spatial grouping principles such as uniform connectedness.

Simulative design in macroscale for prospective application to micro-catheters.

PubMed

Ha, Cheol Woo

2018-02-09

In this paper, a motion-transforming element is applied to the development of a new catheter device. The motion-transforming element structure allows a reduction of linear movement and converts linear movement to rotational movement. The simulative design of micro-catheters is based on a proposed structure called the Operating Mini Station (OMS). OMS is operated by movement of a motion-transforming element. A new motion-transforming element is designed using multiple links that are connected by hinged joints based on an elastic design. The design of the links and the hinges are optimized for precise and reliable movement of the motion-transforming element. Because of the elastic design, it is possible to realize a catheter that allows various movements in small spaces like capillaries.

The effect of transponder motion on the accuracy of the Calypso Electromagnetic localization system.

PubMed

Murphy, Martin J; Eidens, Richard; Vertatschitsch, Edward; Wright, J Nelson

2008-09-01

To determine position and velocity-dependent effects in the overall accuracy of the Calypso Electromagnetic localization system, under conditions that emulate transponder motion during normal free breathing. Three localization transponders were mounted on a remote-controlled turntable that could move the transponders along a circular trajectory at speeds up to 3 cm/s. A stationary calibration established the coordinates of multiple points on each transponder's circular path. Position measurements taken while the transponders were in motion at a constant speed were then compared with the stationary coordinates. No statistically significant changes in the transponder positions in (x,y,z) were detected when the transponders were in motion. The accuracy of the localization system is unaffected by transponder motion.

Inertial Measures of Motion for Clinical Biomechanics: Comparative Assessment of Accuracy under Controlled Conditions – Changes in Accuracy over Time

PubMed Central

Lebel, Karina; Boissy, Patrick; Hamel, Mathieu; Duval, Christian

2015-01-01

Background Interest in 3D inertial motion tracking devices (AHRS) has been growing rapidly among the biomechanical community. Although the convenience of such tracking devices seems to open a whole new world of possibilities for evaluation in clinical biomechanics, its limitations haven’t been extensively documented. The objectives of this study are: 1) to assess the change in absolute and relative accuracy of multiple units of 3 commercially available AHRS over time; and 2) to identify different sources of errors affecting AHRS accuracy and to document how they may affect the measurements over time. Methods This study used an instrumented Gimbal table on which AHRS modules were carefully attached and put through a series of velocity-controlled sustained motions including 2 minutes motion trials (2MT) and 12 minutes multiple dynamic phases motion trials (12MDP). Absolute accuracy was assessed by comparison of the AHRS orientation measurements to those of an optical gold standard. Relative accuracy was evaluated using the variation in relative orientation between modules during the trials. Findings Both absolute and relative accuracy decreased over time during 2MT. 12MDP trials showed a significant decrease in accuracy over multiple phases, but accuracy could be enhanced significantly by resetting the reference point and/or compensating for initial Inertial frame estimation reference for each phase. Interpretation The variation in AHRS accuracy observed between the different systems and with time can be attributed in part to the dynamic estimation error, but also and foremost, to the ability of AHRS units to locate the same Inertial frame. Conclusions Mean accuracies obtained under the Gimbal table sustained conditions of motion suggest that AHRS are promising tools for clinical mobility assessment under constrained conditions of use. However, improvement in magnetic compensation and alignment between AHRS modules are desirable in order for AHRS to reach their full potential in capturing clinical outcomes. PMID:25811838

Listening to Brain Microcircuits for Interfacing With External World-Progress in Wireless Implantable Microelectronic Neuroengineering Devices: Experimental systems are described for electrical recording in the brain using multiple microelectrodes and short range implantable or wearable broadcasting units.

PubMed

Nurmikko, Arto V; Donoghue, John P; Hochberg, Leigh R; Patterson, William R; Song, Yoon-Kyu; Bull, Christopher W; Borton, David A; Laiwalla, Farah; Park, Sunmee; Ming, Yin; Aceros, Juan

2010-01-01

Acquiring neural signals at high spatial and temporal resolution directly from brain microcircuits and decoding their activity to interpret commands and/or prior planning activity, such as motion of an arm or a leg, is a prime goal of modern neurotechnology. Its practical aims include assistive devices for subjects whose normal neural information pathways are not functioning due to physical damage or disease. On the fundamental side, researchers are striving to decipher the code of multiple neural microcircuits which collectively make up nature's amazing computing machine, the brain. By implanting biocompatible neural sensor probes directly into the brain, in the form of microelectrode arrays, it is now possible to extract information from interacting populations of neural cells with spatial and temporal resolution at the single cell level. With parallel advances in application of statistical and mathematical techniques tools for deciphering the neural code, extracted populations or correlated neurons, significant understanding has been achieved of those brain commands that control, e.g., the motion of an arm in a primate (monkey or a human subject). These developments are accelerating the work on neural prosthetics where brain derived signals may be employed to bypass, e.g., an injured spinal cord. One key element in achieving the goals for practical and versatile neural prostheses is the development of fully implantable wireless microelectronic "brain-interfaces" within the body, a point of special emphasis of this paper.

Programmable motion of DNA origami mechanisms.

PubMed

Marras, Alexander E; Zhou, Lifeng; Su, Hai-Jun; Castro, Carlos E

2015-01-20

DNA origami enables the precise fabrication of nanoscale geometries. We demonstrate an approach to engineer complex and reversible motion of nanoscale DNA origami machine elements. We first design, fabricate, and characterize the mechanical behavior of flexible DNA origami rotational and linear joints that integrate stiff double-stranded DNA components and flexible single-stranded DNA components to constrain motion along a single degree of freedom and demonstrate the ability to tune the flexibility and range of motion. Multiple joints with simple 1D motion were then integrated into higher order mechanisms. One mechanism is a crank-slider that couples rotational and linear motion, and the other is a Bennett linkage that moves between a compacted bundle and an expanded frame configuration with a constrained 3D motion path. Finally, we demonstrate distributed actuation of the linkage using DNA input strands to achieve reversible conformational changes of the entire structure on ∼ minute timescales. Our results demonstrate programmable motion of 2D and 3D DNA origami mechanisms constructed following a macroscopic machine design approach.

Programmable motion of DNA origami mechanisms

PubMed Central

Marras, Alexander E.; Zhou, Lifeng; Su, Hai-Jun; Castro, Carlos E.

2015-01-01

DNA origami enables the precise fabrication of nanoscale geometries. We demonstrate an approach to engineer complex and reversible motion of nanoscale DNA origami machine elements. We first design, fabricate, and characterize the mechanical behavior of flexible DNA origami rotational and linear joints that integrate stiff double-stranded DNA components and flexible single-stranded DNA components to constrain motion along a single degree of freedom and demonstrate the ability to tune the flexibility and range of motion. Multiple joints with simple 1D motion were then integrated into higher order mechanisms. One mechanism is a crank–slider that couples rotational and linear motion, and the other is a Bennett linkage that moves between a compacted bundle and an expanded frame configuration with a constrained 3D motion path. Finally, we demonstrate distributed actuation of the linkage using DNA input strands to achieve reversible conformational changes of the entire structure on ∼minute timescales. Our results demonstrate programmable motion of 2D and 3D DNA origami mechanisms constructed following a macroscopic machine design approach. PMID:25561550