Sample records for target-oriented obstacle analysis

  1. Mesoscopic model for filament orientation in growing actin networks: the role of obstacle geometry

    NASA Astrophysics Data System (ADS)

    Weichsel, Julian; Schwarz, Ulrich S.

    2013-03-01

    Propulsion by growing actin networks is a universal mechanism used in many different biological systems, ranging from the sheet-like lamellipodium of crawling animal cells to the actin comet tails induced by certain bacteria and viruses in order to move within their host cells. Although the core molecular machinery for actin network growth is well preserved in all of these cases, the geometry of the propelled obstacle varies considerably. During recent years, filament orientation distribution has emerged as an important observable characterizing the structure and dynamical state of the growing network. Here we derive several continuum equations for the orientation distribution of filaments growing behind stiff obstacles of various shapes and validate the predicted steady state orientation patterns by stochastic computer simulations based on discrete filaments. We use an ordinary differential equation approach to demonstrate that for flat obstacles of finite size, two fundamentally different orientation patterns peaked at either ±35° or +70°/0°/ - 70° exhibit mutually exclusive stability, in agreement with earlier results for flat obstacles of very large lateral extension. We calculate and validate phase diagrams as a function of model parameters and show how this approach can be extended to obstacles with piecewise straight contours. For curved obstacles, we arrive at a partial differential equation in the continuum limit, which again is in good agreement with the computer simulations. In all cases, we can identify the same two fundamentally different orientation patterns, but only within an appropriate reference frame, which is adjusted to the local orientation of the obstacle contour. Our results suggest that two fundamentally different network architectures compete with each other in growing actin networks, irrespective of obstacle geometry, and clarify how simulated and electron tomography data have to be analyzed for non-flat obstacle geometries.

  2. Age-related changes in gait adaptability in response to unpredictable obstacles and stepping targets.

    PubMed

    Caetano, Maria Joana D; Lord, Stephen R; Schoene, Daniel; Pelicioni, Paulo H S; Sturnieks, Daina L; Menant, Jasmine C

    2016-05-01

    A large proportion of falls in older people occur when walking. Limitations in gait adaptability might contribute to tripping; a frequently reported cause of falls in this group. To evaluate age-related changes in gait adaptability in response to obstacles or stepping targets presented at short notice, i.e.: approximately two steps ahead. Fifty older adults (aged 74±7 years; 34 females) and 21 young adults (aged 26±4 years; 12 females) completed 3 usual gait speed (baseline) trials. They then completed the following randomly presented gait adaptability trials: obstacle avoidance, short stepping target, long stepping target and no target/obstacle (3 trials of each). Compared with the young, the older adults slowed significantly in no target/obstacle trials compared with the baseline trials. They took more steps and spent more time in double support while approaching the obstacle and stepping targets, demonstrated poorer stepping accuracy and made more stepping errors (failed to hit the stepping targets/avoid the obstacle). The older adults also reduced velocity of the two preceding steps and shortened the previous step in the long stepping target condition and in the obstacle avoidance condition. Compared with their younger counterparts, the older adults exhibited a more conservative adaptation strategy characterised by slow, short and multiple steps with longer time in double support. Even so, they demonstrated poorer stepping accuracy and made more stepping errors. This reduced gait adaptability may place older adults at increased risk of falling when negotiating unexpected hazards. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. Constructing target product profiles (TPPs) to help vaccines overcome post-approval obstacles

    PubMed Central

    Lee, Bruce Y.; Burke, Donald S.

    2012-01-01

    As history has demonstrated, post-approval obstacles can impede a vaccine’s use and potentially lead to its withdrawal. Addressing these potential obstacles when changes in a vaccine’s technology can still be easily made may improve a vaccine’s chances of success. Augmented vaccine target product profiles (TPPs) can help vaccine scientists better understand and anticipate these obstacles and galvanize conversations among various vaccine stakeholders (e.g., scientists, marketers, business development managers, policy makers, public health officials, health care workers, third party payors, etc.) earlier in a vaccine’s development. PMID:19782109

  4. Three-dimensional obstacle classification in laser range data

    NASA Astrophysics Data System (ADS)

    Armbruster, Walter; Bers, Karl-Heinz

    1998-10-01

    The threat of hostile surveillance and weapon systems require military aircraft to fly under extreme conditions such as low altitude, high speed, poor visibility and incomplete terrain information. The probability of collision with natural and man-made obstacles during such contour missions is high if detection capability is restricted to conventional vision aids. Forward-looking scanning laser rangefinders which are presently being flight tested and evaluated at German proving grounds, provide a possible solution, having a large field of view, high angular and range resolution, a high pulse repetition rate, and sufficient pulse energy to register returns from wires at over 500 m range (depends on the system) with a high hit-and-detect probability. Despite the efficiency of the sensor, acceptance of current obstacle warning systems by test pilots is not very high, mainly due to the systems' inadequacies in obstacle recognition and visualization. This has motivated the development and the testing of more advanced 3d-scene analysis algorithm at FGAN-FIM to replace the obstacle recognition component of current warning systems. The basic ideas are to increase the recognition probability and to reduce the false alarm rate for hard-to-extract obstacles such as wires, by using more readily recognizable objects such as terrain, poles, pylons, trees, etc. by implementing a hierarchical classification procedure to generate a parametric description of the terrain surface as well as the class, position, orientation, size and shape of all objects in the scene. The algorithms can be used for other applications such as terrain following, autonomous obstacle avoidance, and automatic target recognition.

  5. Laser radar system for obstacle avoidance

    NASA Astrophysics Data System (ADS)

    Bers, Karlheinz; Schulz, Karl R.; Armbruster, Walter

    2005-09-01

    The threat of hostile surveillance and weapon systems require military aircraft to fly under extreme conditions such as low altitude, high speed, poor visibility and incomplete terrain information. The probability of collision with natural and man-made obstacles during such contour missions is high if detection capability is restricted to conventional vision aids. Forward-looking scanning laser radars which are build by the EADS company and presently being flight tested and evaluated at German proving grounds, provide a possible solution, having a large field of view, high angular and range resolution, a high pulse repetition rate, and sufficient pulse energy to register returns from objects at distances of military relevance with a high hit-and-detect probability. The development of advanced 3d-scene analysis algorithms had increased the recognition probability and reduced the false alarm rate by using more readily recognizable objects such as terrain, poles, pylons, trees, etc. to generate a parametric description of the terrain surface as well as the class, position, orientation, size and shape of all objects in the scene. The sensor system and the implemented algorithms can be used for other applications such as terrain following, autonomous obstacle avoidance, and automatic target recognition. This paper describes different 3D-imaging ladar sensors with unique system architecture but different components matched for different military application. Emphasis is laid on an obstacle warning system with a high probability of detection of thin wires, the real time processing of the measured range image data, obstacle classification und visualization.

  6. Antigenic variability: Obstacles on the road to vaccines against traditionally difficult targets.

    PubMed

    Servín-Blanco, R; Zamora-Alvarado, R; Gevorkian, G; Manoutcharian, K

    2016-10-02

    Despite the impressive impact of vaccines on public health, the success of vaccines targeting many important pathogens and cancers has to date been limited. The burden of infectious diseases today is mainly caused by antigenically variable pathogens (AVPs), which escape immune responses induced by prior infection or vaccination through changes in molecular structures recognized by antibodies or T cells. Extensive genetic and antigenic variability is the major obstacle for the development of new or improved vaccines against "difficult" targets. Alternative, qualitatively new approaches leading to the generation of disease- and patient-specific vaccine immunogens that incorporate complex permanently changing epitope landscapes of intended targets accompanied by appropriate immunomodulators are urgently needed. In this review, we highlight some of the most critical common issues related to the development of vaccines against many pathogens and cancers that escape protective immune responses owing to antigenic variation, and discuss recent efforts to overcome the obstacles by applying alternative approaches for the rational design of new types of immunogens.

  7. Obstacle Avoidance and Target Acquisition for Robot Navigation Using a Mixed Signal Analog/Digital Neuromorphic Processing System

    PubMed Central

    Milde, Moritz B.; Blum, Hermann; Dietmüller, Alexander; Sumislawska, Dora; Conradt, Jörg; Indiveri, Giacomo; Sandamirskaya, Yulia

    2017-01-01

    Neuromorphic hardware emulates dynamics of biological neural networks in electronic circuits offering an alternative to the von Neumann computing architecture that is low-power, inherently parallel, and event-driven. This hardware allows to implement neural-network based robotic controllers in an energy-efficient way with low latency, but requires solving the problem of device variability, characteristic for analog electronic circuits. In this work, we interfaced a mixed-signal analog-digital neuromorphic processor ROLLS to a neuromorphic dynamic vision sensor (DVS) mounted on a robotic vehicle and developed an autonomous neuromorphic agent that is able to perform neurally inspired obstacle-avoidance and target acquisition. We developed a neural network architecture that can cope with device variability and verified its robustness in different environmental situations, e.g., moving obstacles, moving target, clutter, and poor light conditions. We demonstrate how this network, combined with the properties of the DVS, allows the robot to avoid obstacles using a simple biologically-inspired dynamics. We also show how a Dynamic Neural Field for target acquisition can be implemented in spiking neuromorphic hardware. This work demonstrates an implementation of working obstacle avoidance and target acquisition using mixed signal analog/digital neuromorphic hardware. PMID:28747883

  8. Obstacle Avoidance and Target Acquisition for Robot Navigation Using a Mixed Signal Analog/Digital Neuromorphic Processing System.

    PubMed

    Milde, Moritz B; Blum, Hermann; Dietmüller, Alexander; Sumislawska, Dora; Conradt, Jörg; Indiveri, Giacomo; Sandamirskaya, Yulia

    2017-01-01

    Neuromorphic hardware emulates dynamics of biological neural networks in electronic circuits offering an alternative to the von Neumann computing architecture that is low-power, inherently parallel, and event-driven. This hardware allows to implement neural-network based robotic controllers in an energy-efficient way with low latency, but requires solving the problem of device variability, characteristic for analog electronic circuits. In this work, we interfaced a mixed-signal analog-digital neuromorphic processor ROLLS to a neuromorphic dynamic vision sensor (DVS) mounted on a robotic vehicle and developed an autonomous neuromorphic agent that is able to perform neurally inspired obstacle-avoidance and target acquisition. We developed a neural network architecture that can cope with device variability and verified its robustness in different environmental situations, e.g., moving obstacles, moving target, clutter, and poor light conditions. We demonstrate how this network, combined with the properties of the DVS, allows the robot to avoid obstacles using a simple biologically-inspired dynamics. We also show how a Dynamic Neural Field for target acquisition can be implemented in spiking neuromorphic hardware. This work demonstrates an implementation of working obstacle avoidance and target acquisition using mixed signal analog/digital neuromorphic hardware.

  9. Unpinning of spiral waves from rectangular obstacles by stimulated wave trains

    NASA Astrophysics Data System (ADS)

    Ponboonjaroenchai, Benjamas; Srithamma, Panatda; Kumchaiseemak, Nakorn; Sutthiopad, Malee; Müller, Stefan C.; Luengviriya, Chaiya; Luengviriya, Jiraporn

    2017-09-01

    Pinned spiral waves are exhibited in many excitable media. In cardiology, lengthened tachycardia correspond to propagating action potential in forms of spiral waves pinned to anatomical obstacles including veins and scares. Thus, elimination such waves is important particularly in medical treatments. We present study of unpinning of a spiral wave by a wave train initiated by periodic stimuli at a given location. The spiral wave is forced to leave the rectangular obstacle when the period of the wave train is shorter than a threshold Tunpin. For small obstacles, Tunpin decreases when the obstacle size is increased. Furthermore, Tunpin depends on the obstacle orientation with respect to the wave train propagation. For large obstacles, Tunpin is independent to the obstacle size. It implies that the orientation of the obstacle plays an important role in the unpinning of the spiral wave, especially for small rectangular obstacles.

  10. Target oriented dimensionality reduction of hyperspectral data by Kernel Fukunaga-Koontz Transform

    NASA Astrophysics Data System (ADS)

    Binol, Hamidullah; Ochilov, Shuhrat; Alam, Mohammad S.; Bal, Abdullah

    2017-02-01

    Principal component analysis (PCA) is a popular technique in remote sensing for dimensionality reduction. While PCA is suitable for data compression, it is not necessarily an optimal technique for feature extraction, particularly when the features are exploited in supervised learning applications (Cheriyadat and Bruce, 2003) [1]. Preserving features belonging to the target is very crucial to the performance of target detection/recognition techniques. Fukunaga-Koontz Transform (FKT) based supervised band reduction technique can be used to provide this requirement. FKT achieves feature selection by transforming into a new space in where feature classes have complimentary eigenvectors. Analysis of these eigenvectors under two classes, target and background clutter, can be utilized for target oriented band reduction since each basis functions best represent target class while carrying least information of the background class. By selecting few eigenvectors which are the most relevant to the target class, dimension of hyperspectral data can be reduced and thus, it presents significant advantages for near real time target detection applications. The nonlinear properties of the data can be extracted by kernel approach which provides better target features. Thus, we propose constructing kernel FKT (KFKT) to present target oriented band reduction. The performance of the proposed KFKT based target oriented dimensionality reduction algorithm has been tested employing two real-world hyperspectral data and results have been reported consequently.

  11. UAVs Task and Motion Planning in the Presence of Obstacles and Prioritized Targets

    PubMed Central

    Gottlieb, Yoav; Shima, Tal

    2015-01-01

    The intertwined task assignment and motion planning problem of assigning a team of fixed-winged unmanned aerial vehicles to a set of prioritized targets in an environment with obstacles is addressed. It is assumed that the targets’ locations and initial priorities are determined using a network of unattended ground sensors used to detect potential threats at restricted zones. The targets are characterized by a time-varying level of importance, and timing constraints must be fulfilled before a vehicle is allowed to visit a specific target. It is assumed that the vehicles are carrying body-fixed sensors and, thus, are required to approach a designated target while flying straight and level. The fixed-winged aerial vehicles are modeled as Dubins vehicles, i.e., having a constant speed and a minimum turning radius constraint. The investigated integrated problem of task assignment and motion planning is posed in the form of a decision tree, and two search algorithms are proposed: an exhaustive algorithm that improves over run time and provides the minimum cost solution, encoded in the tree, and a greedy algorithm that provides a quick feasible solution. To satisfy the target’s visitation timing constraint, a path elongation motion planning algorithm amidst obstacles is provided. Using simulations, the performance of the algorithms is compared, evaluated and exemplified. PMID:26610522

  12. Speeded Reaching Movements around Invisible Obstacles

    PubMed Central

    Hudson, Todd E.; Wolfe, Uta; Maloney, Laurence T.

    2012-01-01

    We analyze the problem of obstacle avoidance from a Bayesian decision-theoretic perspective using an experimental task in which reaches around a virtual obstacle were made toward targets on an upright monitor. Subjects received monetary rewards for touching the target and incurred losses for accidentally touching the intervening obstacle. The locations of target-obstacle pairs within the workspace were varied from trial to trial. We compared human performance to that of a Bayesian ideal movement planner (who chooses motor strategies maximizing expected gain) using the Dominance Test employed in Hudson et al. (2007). The ideal movement planner suffers from the same sources of noise as the human, but selects movement plans that maximize expected gain in the presence of that noise. We find good agreement between the predictions of the model and actual performance in most but not all experimental conditions. PMID:23028276

  13. Railway obstacle detection algorithm using neural network

    NASA Astrophysics Data System (ADS)

    Yu, Mingyang; Yang, Peng; Wei, Sen

    2018-05-01

    Aiming at the difficulty of detection of obstacle in outdoor railway scene, a data-oriented method based on neural network to obtain image objects is proposed. First, we mark objects of images(such as people, trains, animals) acquired on the Internet. and then use the residual learning units to build Fast R-CNN framework. Then, the neural network is trained to get the target image characteristics by using stochastic gradient descent algorithm. Finally, a well-trained model is used to identify an outdoor railway image. if it includes trains and other objects, it will issue an alert. Experiments show that the correct rate of warning reached 94.85%.

  14. Collective rotations of active particles interacting with obstacles

    NASA Astrophysics Data System (ADS)

    Mokhtari, Zahra; Aspelmeier, Timo; Zippelius, Annette

    2017-10-01

    We consider active particles in a heterogeneous medium, modeled by static, random obstacles. In accordance with the known tendency of active particles to cluster, we observe accumulation and crystallization of active particles around the obstacles which serve as nucleation sites. In the limit of high activity, the crystals start to rotate spontaneously, resembling a rotating rigid body. We trace the occurrence of these oscillations to the enhanced attraction of particles whose orientation points along the rotational velocity as compared to those whose orientation points in the opposite direction.

  15. Does practicing a wide range of joint angle configurations lead to higher flexibility in a manual obstacle-avoidance target-pointing task?

    PubMed Central

    Bootsma, Reinoud J.; Schoemaker, Marina M.; Otten, Egbert; Mouton, Leonora J.; Bongers, Raoul M.

    2017-01-01

    Flexibility in motor actions can be defined as variability in the use of degrees of freedom (e.g., joint angles in the arm) over repetitions while keeping performance (e.g., fingertip position) stabilized. We examined whether flexibility can be increased through enlarging the joint angle range during practice in a manual obstacle-avoidance target-pointing task. To establish differences in flexibility we partitioned the variability in joint angles over repetitions in variability within (GEV) and variability outside the solution space (NGEV). More GEV than NGEV reflects flexibility; when the ratio of the GEV and NGEV is higher, flexibility is higher. The pretest and posttest consisted of 30 repetitions of manual pointing to a target while moving over a 10 cm high obstacle. To enlarge the joint angle range during practice participants performed 600 target-pointing movements while moving over obstacles of different heights (5–9 cm, 11–15 cm). The results indicated that practicing movements over obstacles of different heights led participants to use enlarged range of joint angles compared to the range of joint angles used in movements over the 10 cm obstacle in the pretest. However, for each individual obstacle neither joint angle variance nor flexibility were higher during practice. We also did not find more flexibility after practice. In the posttest, joint angle variance was in fact smaller than before practice, primarily in GEV. The potential influences of learning effects and the task used that could underlie the results obtained are discussed. We conclude that with this specific type of practice in this specific task, enlarging the range of joint angles does not lead to more flexibility. PMID:28700695

  16. Contrast, size, and orientation-invariant target detection in infrared imagery

    NASA Astrophysics Data System (ADS)

    Zhou, Yi-Tong; Crawshaw, Richard D.

    1991-08-01

    Automatic target detection in IR imagery is a very difficult task due to variations in target brightness, shape, size, and orientation. In this paper, the authors present a contrast, size, and orientation invariant algorithm based on Gabor functions for detecting targets from a single IR image frame. The algorithms consists of three steps. First, it locates potential targets by using low-resolution Gabor functions which resist noise and background clutter effects, then, it removes false targets and eliminates redundant target points based on a similarity measure. These two steps mimic human vision processing but are different from Zeevi's Foveating Vision System. Finally, it uses both low- and high-resolution Gabor functions to verify target existence. This algorithm has been successfully tested on several IR images that contain multiple examples of military vehicles with different size and brightness in various background scenes and orientations.

  17. Obstacle-avoiding navigation system

    DOEpatents

    Borenstein, Johann; Koren, Yoram; Levine, Simon P.

    1991-01-01

    A system for guiding an autonomous or semi-autonomous vehicle through a field of operation having obstacles thereon to be avoided employs a memory for containing data which defines an array of grid cells which correspond to respective subfields in the field of operation of the vehicle. Each grid cell in the memory contains a value which is indicative of the likelihood, or probability, that an obstacle is present in the respectively associated subfield. The values in the grid cells are incremented individually in response to each scan of the subfields, and precomputation and use of a look-up table avoids complex trigonometric functions. A further array of grid cells is fixed with respect to the vehicle form a conceptual active window which overlies the incremented grid cells. Thus, when the cells in the active window overly grid cell having values which are indicative of the presence of obstacles, the value therein is used as a multiplier of the precomputed vectorial values. The resulting plurality of vectorial values are summed vectorially in one embodiment of the invention to produce a virtual composite repulsive vector which is then summed vectorially with a target-directed vector for producing a resultant vector for guiding the vehicle. In an alternative embodiment, a plurality of vectors surrounding the vehicle are computed, each having a value corresponding to obstacle density. In such an embodiment, target location information is used to select between alternative directions of travel having low associated obstacle densities.

  18. Promotion of Students' Mastery Goal Orientations: Does TARGET Work?

    ERIC Educational Resources Information Center

    Lüftenegger, Marko; van de Schoot, Rens; Schober, Barbara; Finsterwald, Monika; Spiel, Christiane

    2014-01-01

    Achievement goal orientations are important for students' ongoing motivation. Students with a mastery goal orientation show the most advantageous achievement and motivational patterns. Much research has been conducted to identify classroom structures which promote students' mastery goal orientation. The TARGET framework is one example of these…

  19. Texture orientation-based algorithm for detecting infrared maritime targets.

    PubMed

    Wang, Bin; Dong, Lili; Zhao, Ming; Wu, Houde; Xu, Wenhai

    2015-05-20

    Infrared maritime target detection is a key technology for maritime target searching systems. However, in infrared maritime images (IMIs) taken under complicated sea conditions, background clutters, such as ocean waves, clouds or sea fog, usually have high intensity that can easily overwhelm the brightness of real targets, which is difficult for traditional target detection algorithms to deal with. To mitigate this problem, this paper proposes a novel target detection algorithm based on texture orientation. This algorithm first extracts suspected targets by analyzing the intersubband correlation between horizontal and vertical wavelet subbands of the original IMI on the first scale. Then the self-adaptive wavelet threshold denoising and local singularity analysis of the original IMI is combined to remove false alarms further. Experiments show that compared with traditional algorithms, this algorithm can suppress background clutter much better and realize better single-frame detection for infrared maritime targets. Besides, in order to guarantee accurate target extraction further, the pipeline-filtering algorithm is adopted to eliminate residual false alarms. The high practical value and applicability of this proposed strategy is backed strongly by experimental data acquired under different environmental conditions.

  20. Healthy young adults implement distinctive avoidance strategies while walking and circumventing virtual human vs. non-human obstacles in a virtual environment.

    PubMed

    Souza Silva, Wagner; Aravind, Gayatri; Sangani, Samir; Lamontagne, Anouk

    2018-03-01

    This study examines how three types of obstacles (cylinder, virtual human and virtual human with footstep sounds) affect circumvention strategies of healthy young adults. Sixteen participants aged 25.2 ± 2.5 years (mean ± 1SD) were tested while walking overground and viewing a virtual room through a helmet mounted display. As participants walked towards a stationary target in the far space, they avoided an obstacle (cylinder or virtual human) approaching either from the right (+40°), left (-40°) or head-on (0°). Obstacle avoidance strategies were characterized using the position and orientation of the head. Repeated mixed model analysis showed smaller minimal distances (p = 0.007) while avoiding virtual humans as compared to cylinders. Footstep sounds added to virtual humans did not modify (p = 0.2) minimal distances compared to when no sound was provided. Onset times of avoidance strategies were similar across conditions (p = 0.06). Results indicate that the nature of the obstacle (human-like vs. non-human object) matters and can modify avoidance strategies. Smaller obstacle clearances in response to virtual humans may reflect the use of a less conservative avoidance strategy, due to a resemblance of obstacles to pedestrians and a recall of strategies used in daily locomotion. The lack of influence of footstep sounds supports the fact that obstacle avoidance primarily relies on visual cues and the principle of 'inverse effectiveness' whereby multisensory neurons' response to multimodal stimuli becomes weaker when the unimodal sensory stimulus (vision) is strong. Present findings should be taken into consideration to optimize the ecological validity of VR-based obstacle avoidance paradigms used in research and rehabilitation. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. Managing Systemic Curriculum Change: A Critical Analysis of Hong Kong's Target-Oriented Curriculum Initiative.

    ERIC Educational Resources Information Center

    Carless, David

    1997-01-01

    Describes Hong Kong's Target-Oriented Curriculum (TOC), a major curriculum renewal initiative designed to improve the quality of learning in local primary schools. Discusses the context in which it was introduced and factors that proved problematic in managing change. Focuses on five elements in the change process: practicality, ownership, teacher…

  2. An enhanced MMW and SMMW/THz imaging system performance prediction and analysis tool for concealed weapon detection and pilotage obstacle avoidance

    NASA Astrophysics Data System (ADS)

    Murrill, Steven R.; Jacobs, Eddie L.; Franck, Charmaine C.; Petkie, Douglas T.; De Lucia, Frank C.

    2015-10-01

    The U.S. Army Research Laboratory (ARL) has continued to develop and enhance a millimeter-wave (MMW) and submillimeter- wave (SMMW)/terahertz (THz)-band imaging system performance prediction and analysis tool for both the detection and identification of concealed weaponry, and for pilotage obstacle avoidance. The details of the MATLAB-based model which accounts for the effects of all critical sensor and display components, for the effects of atmospheric attenuation, concealment material attenuation, and active illumination, were reported on at the 2005 SPIE Europe Security and Defence Symposium (Brugge). An advanced version of the base model that accounts for both the dramatic impact that target and background orientation can have on target observability as related to specular and Lambertian reflections captured by an active-illumination-based imaging system, and for the impact of target and background thermal emission, was reported on at the 2007 SPIE Defense and Security Symposium (Orlando). Further development of this tool that includes a MODTRAN-based atmospheric attenuation calculator and advanced system architecture configuration inputs that allow for straightforward performance analysis of active or passive systems based on scanning (single- or line-array detector element(s)) or staring (focal-plane-array detector elements) imaging architectures was reported on at the 2011 SPIE Europe Security and Defence Symposium (Prague). This paper provides a comprehensive review of a newly enhanced MMW and SMMW/THz imaging system analysis and design tool that now includes an improved noise sub-model for more accurate and reliable performance predictions, the capability to account for postcapture image contrast enhancement, and the capability to account for concealment material backscatter with active-illumination- based systems. Present plans for additional expansion of the model's predictive capabilities are also outlined.

  3. [Orienting reflex: "targeting reaction" and "searchlight of attention"].

    PubMed

    Sokolov, E N; Nezlina, N I; Polianskiĭ, V B; Evtikhin, D V

    2001-01-01

    The concept of orienting reflex based on the principle of vector coding of cognitive and executive processes is proposed. The orienting reflex to non-signal and signal stimuli is a set of orienting reactions: motor, autonomic, neuronal, and subjective emphasizing new and significant stimuli. Two basic mechanisms can be identified within the orienting reflex: a "targeting reaction" and a "searchlight of attention". In the visual system the first one consists in a foveation of a target stimulus. The foveation is performed with participation of premotor neurons excited by saccadic command neurons of the superior colliculi. The "searchlight of attention" is based on the resonance of gamma-oscillations in the reticular thalamus selectively enhancing responses of cortical neurons (involuntary attention). The novelty signal is generated in novelty neurons of the hippocampus, which are selectively tuned to a repeatedly presented standard stimulus. The selective tuning is caused by the depression of plastic synapses representing a "neuronal model" of the standard stimulus. A mismatch of the novel stimulus with the established neuronal model gives rise to a "novelty signal" enhancing the novel input. The novelty signal inhibits current conditioned reflexes (external inhibition) contributing to redirecting the behavior. By triggering the expression of early genes the novelty signal initiates the formation of the long-term memory connected with neoneurogenesis.

  4. Obstacles to the implementation of the treat-to-target strategy for rheumatoid arthritis in clinical practice in Japan.

    PubMed

    Kaneko, Yuko; Koike, Takao; Oda, Hiromi; Yamamoto, Kazuhiko; Miyasaka, Nobuyuki; Harigai, Masayoshi; Yamanaka, Hisashi; Ishiguro, Naoki; Tanaka, Yoshiya; Takeuchi, Tsutomu

    2015-01-01

    To clarify the obstacles preventing the implementation of the treat-to-target (T2T) strategy for rheumatoid arthritis (RA) in clinical practice. A total of 301 rheumatologists in Japan completed a questionnaire. In the first section, participants were indirectly questioned on the implementation of basic components of T2T, and in the second section, participants were directly questioned on their level of agreement and application. Although nearly all participants set treatment targets for the majority of RA patients with moderate to high disease activity, the proportion who set clinical remission as their target was 59%, with only 45% of these using composite measures. The proportion of participants who monitored X-rays and Health Assessment Questionnaires for all their patients was 44% and 14%, respectively. The proportion of participants who did not discuss treatment strategies was 44%, with approximately half of these reasoning that this was due to a proportion of patients having a lack of understanding of the treatment strategy or inability to make decisions. When participants were directly questioned, there was a high level of agreement with the T2T recommendations. Although there was a high level of agreement with the T2T recommendations, major obstacles preventing its full implementation still remain.

  5. Target-object integration, attention distribution, and object orientation interactively modulate object-based selection.

    PubMed

    Al-Janabi, Shahd; Greenberg, Adam S

    2016-10-01

    The representational basis of attentional selection can be object-based. Various studies have suggested, however, that object-based selection is less robust than spatial selection across experimental paradigms. We sought to examine the manner by which the following factors might explain this variation: Target-Object Integration (targets 'on' vs. part 'of' an object), Attention Distribution (narrow vs. wide), and Object Orientation (horizontal vs. vertical). In Experiment 1, participants discriminated between two targets presented 'on' an object in one session, or presented as a change 'of' an object in another session. There was no spatial cue-thus, attention was initially focused widely-and the objects were horizontal or vertical. We found evidence of object-based selection only when targets constituted a change 'of' an object. Additionally, object orientation modulated the sign of object-based selection: We observed a same-object advantage for horizontal objects, but a same-object cost for vertical objects. In Experiment 2, an informative cue preceded a single target presented 'on' an object or as a change 'of' an object (thus, attention was initially focused narrowly). Unlike in Experiment 1, we found evidence of object-based selection independent of target-object integration. We again found that the sign of selection was modulated by the objects' orientation. This result may reflect a meridian effect, which emerged due to anisotropies in the cortical representations when attention is oriented endogenously. Experiment 3 revealed that object orientation did not modulate object-based selection when attention was oriented exogenously. Our findings suggest that target-object integration, attention distribution, and object orientation modulate object-based selection, but only in combination.

  6. Obstacle avoidance and concealed target detection using the Army Research Lab ultra-wideband synchronous impulse reconstruction (UWB SIRE) forward imaging radar

    NASA Astrophysics Data System (ADS)

    Nguyen, Lam; Wong, David; Ressler, Marc; Koenig, Francois; Stanton, Brian; Smith, Gregory; Sichina, Jeffrey; Kappra, Karl

    2007-04-01

    The U.S. Army Research Laboratory (ARL), as part of a mission and customer funded exploratory program, has developed a new low-frequency, ultra-wideband (UWB) synthetic aperture radar (SAR) for forward imaging to support the Army's vision of an autonomous navigation system for robotic ground vehicles. These unmanned vehicles, equipped with an array of imaging sensors, will be tasked to help detect man-made obstacles such as concealed targets, enemy minefields, and booby traps, as well as other natural obstacles such as ditches, and bodies of water. The ability of UWB radar technology to help detect concealed objects has been documented in the past and could provide an important obstacle avoidance capability for autonomous navigation systems, which would improve the speed and maneuverability of these vehicles and consequently increase the survivability of the U. S. forces on the battlefield. One of the primary features of the radar is the ability to collect and process data at combat pace in an affordable, compact, and lightweight package. To achieve this, the radar is based on the synchronous impulse reconstruction (SIRE) technique where several relatively slow and inexpensive analog-to-digital (A/D) converters are used to sample the wide bandwidth of the radar signals. We conducted an experiment this winter at Aberdeen Proving Ground (APG) to support the phenomenological studies of the backscatter from positive and negative obstacles for autonomous robotic vehicle navigation, as well as the detection of concealed targets of interest to the Army. In this paper, we briefly describe the UWB SIRE radar and the test setup in the experiment. We will also describe the signal processing and the forward imaging techniques used in the experiment. Finally, we will present imagery of man-made obstacles such as barriers, concertina wires, and mines.

  7. Plant root and shoot dynamics during subsurface obstacle interaction

    NASA Astrophysics Data System (ADS)

    Conn, Nathaniel; Aguilar, Jeffrey; Benfey, Philip; Goldman, Daniel

    As roots grow, they must navigate complex underground environments to anchor and retrieve water and nutrients. From gravity sensing at the root tip to pressure sensing along the tip and elongation zone, the complex mechanosensory feedback system of the root allows it to bend towards greater depths and avoid obstacles of high impedance by asymmetrically suppressing cell elongation. Here we investigate the mechanical and physiological responses of roots to rigid obstacles. We grow Maize, Zea mays, plants in quasi-2D glass containers (22cm x 17cm x 1.4cm) filled with photoelastic gel and observe that, regardless of obstacle interaction, smaller roots branch off the primary root when the upward growing shoot (which contains the first leaf) reaches an average length of 40 mm, coinciding with when the first leaf emerges. However, prior to branching, contacts with obstacles result in reduced root growth rates. The growth rate of the root relative to the shoot is sensitive to the angle of the obstacle surface, whereby the relative root growth is greatest for horizontally oriented surfaces. We posit that root growth is prioritized when horizontal obstacles are encountered to ensure anchoring and access to nutrients during later stages of development. NSF Physics of Living Systems.

  8. Laser tracker orientation in confined space using on-board targets

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Kyle, Stephen; Lin, Jiarui; Yang, Linghui; Ren, Yu; Zhu, Jigui

    2016-08-01

    This paper presents a novel orientation method for two laser trackers using on-board targets attached to the tracker head and rotating with it. The technique extends an existing method developed for theodolite intersection systems which are now rarely used. This method requires only a very narrow space along the baseline between the instrument heads, in order to establish the orientation relationship. This has potential application in environments where space is restricted. The orientation parameters can be calculated by means of two-face reciprocal measurements to the on-board targets, and measurements to a common point close to the baseline. An accurate model is then applied which can be solved through nonlinear optimization. Experimental comparison has been made with the conventional orientation method, which is based on measurements to common intersection points located off the baseline. This requires more space and the comparison has demonstrated the feasibility of the more compact technique presented here. Physical setup and testing suggest that the method is practical. Uncertainties estimated by simulation indicate good performance in terms of measurement quality.

  9. SU-E-T-133: Dosimetric Impact of Scan Orientation Relative to Target Motion During Spot Scanning Proton Therapy

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

    Stoker, J; Summers, P; Li, X

    2014-06-01

    Purpose: This study seeks to evaluate the dosimetric effects of intra-fraction motion during spot scanning proton beam therapy as a function of beam-scan orientation and target motion amplitude. Method: Multiple 4DCT scans were collected of a dynamic anthropomorphic phantom mimicking respiration amplitudes of 0 (static), 0.5, 1.0, and 1.5 cm. A spot-scanning treatment plan was developed on the maximum intensity projection image set, using an inverse-planning approach. Dynamic phantom motion was continuous throughout treatment plan delivery.The target nodule was designed to accommodate film and thermoluminescent dosimeters (TLD). Film and TLDs were uniquely labeled by location within the target. The phantommore » was localized on the treatment table using the clinically available orthogonal kV on-board imaging device. Film inserts provided data for dose uniformity; TLDs provided a 3% precision estimate of absolute dose. An inhouse script was developed to modify the delivery order of the beam spots, to orient the scanning direction parallel or perpendicular to target motion.TLD detector characterization and analysis was performed by the Imaging and Radiation Oncology Core group (IROC)-Houston. Film inserts, exhibiting a spatial resolution of 1mm, were analyzed to determine dose homogeneity within the radiation target. Results: Parallel scanning and target motions exhibited reduced target dose heterogeneity, relative to perpendicular scanning orientation. The average percent deviation in absolute dose for the motion deliveries relative to the static delivery was 4.9±1.1% for parallel scanning, and 11.7±3.5% (p<<0.05) for perpendicularly oriented scanning. Individual delivery dose deviations were not necessarily correlated to amplitude of motion for either scan orientation. Conclusions: Results demonstrate a quantifiable difference in dose heterogeneity as a function of scan orientation, more so than target amplitude. Comparison to the analyzed planar dose of a

  10. An Empirical Analysis of Chinese College Learners' Obstacles to MOOC Learning in an English Context

    ERIC Educational Resources Information Center

    Liu, Liangxing

    2017-01-01

    This article reports a study applying an exploratory factor analysis to discovering the underlying factor structure of Chinese college students' obstacles to learning MOOC in an English context. Seven obstacle factors are identified: 1. academic and language skills; 2. internet skills; 3. course instruction/management; 4. learning motivations; 5.…

  11. Identifying Contingency Requirements using Obstacle Analysis on an Unpiloted Aerial Vehicle

    NASA Technical Reports Server (NTRS)

    Lutz, Robyn R.; Nelson, Stacy; Patterson-Hine, Ann; Frost, Chad R.; Tal, Doron

    2005-01-01

    This paper describes experience using Obstacle Analysis to identify contingency requirements on an unpiloted aerial vehicle. A contingency is an operational anomaly, and may or may not involve component failure. The challenges to this effort were: ( I ) rapid evolution of the system while operational, (2) incremental autonomy as capabilities were transferred from ground control to software control and (3) the eventual safety-criticality of such systems as they begin to fly over populated areas. The results reported here are preliminary but show that Obstacle Analysis helped (1) identify new contingencies that appeared as autonomy increased; (2) identify new alternatives for handling both previously known and new contingencies; and (3) investigate the continued validity of existing software requirements for contingency handling. Since many mobile, intelligent systems are built using a development process that poses the same challenges, the results appear to have applicability to other similar systems.

  12. Analysis of the obstacles related to treatment entry, adherence and drop-out among alcoholic patients.

    PubMed

    Fonsi Elbreder, Márcia; Carvalho De Humerez, Dorisdaia; Laranjeira, Ronaldo

    2009-01-01

    Alcoholism is a complex syndrome involving social, psychological and individual factors in addition to a series of obstacles regarding treatment entry, adherence, and drop-out. These obstacles contribute negatively to both clinical evolution and prognosis of the patients, affecting their quality of life and raising the social costs. This is a bibliographical study in which we address this theme as well as other experiences observed in our daily practice in the Alcohol and Drug Research Unit (UNIAD) based at the Federal University of São Paulo (UNIFESP). The analysis of the obstacles related to treatment entry, attendance, and drop-out among alcoholic patients shows that systemic, social, cultural, and individual factors are all involved, including the structural ones. Women have more obstacles compared to men, and what is thought to be a barrier to one patient may be a factor motivating another patient to search for help. We conclude that several factors at different levels exist that prevent the patient from overcoming these treatment obstacles.

  13. Attention to baseline: does orienting visuospatial attention really facilitate target detection?

    PubMed

    Albares, Marion; Criaud, Marion; Wardak, Claire; Nguyen, Song Chi Trung; Ben Hamed, Suliann; Boulinguez, Philippe

    2011-08-01

    Standard protocols testing the orientation of visuospatial attention usually present spatial cues before targets and compare valid-cue trials with invalid-cue trials. The valid/invalid contrast results in a relative behavioral or physiological difference that is generally interpreted as a benefit of attention orientation. However, growing evidence suggests that inhibitory control of response is closely involved in this kind of protocol that requires the subjects to withhold automatic responses to cues, probably biasing behavioral and physiological baselines. Here, we used two experiments to disentangle the inhibitory control of automatic responses from orienting of visuospatial attention in a saccadic reaction time task in humans, a variant of the classical cue-target detection task and a sustained visuospatial attentional task. Surprisingly, when referring to a simple target detection task in which there is no need to refrain from reacting to avoid inappropriate responses, we found no consistent evidence of facilitation of target detection at the attended location. Instead, we observed a cost at the unattended location. Departing from the classical view, our results suggest that reaction time measures of visuospatial attention probably relie on the attenuation of elementary processes involved in visual target detection and saccade initiation away from the attended location rather than on facilitation at the attended location. This highlights the need to use proper control conditions in experimental designs to disambiguate relative from absolute cueing benefits on target detection reaction times, both in psychophysical and neurophysiological studies.

  14. Women's orgasm obstacles: A qualitative study.

    PubMed

    Nekoolaltak, Maryam; Keshavarz, Zohreh; Simbar, Masoumeh; Nazari, Ali Mohammad; Baghestani, Ahmad Reza

    2017-08-01

    Woman's orgasm plays a vital role in sexual compatibility and marital satisfaction. Orgasm in women is a learnable phenomenon that is influenced by several factors. The aim of this study is exploring obstacles to orgasm in Iranian married women. This qualitative study with directed content analysis approach was conducted in 2015-2016, on 20 Iranian married women who were individually interviewed at two medical clinics in Tehran, Iran. Orgasm obstacles were explored in one category, 4 subcategories, and 25 codes. The main category was "Multidimensionality of women's orgasm obstacles". Subcategories and some codes included: Physical obstacles (wife's or husband's boredom, vaginal infection, insufficient vaginal lubrication), psychological obstacles (lack of sexual knowledge, shame, lack of concentration on sex due to household and children problems), relational obstacles (husband's hurry, having a dispute and annoyance with spouse) and contextual obstacles (Irregular sleep hours, lack of privacy and inability to separate children's bedroom from their parents, lack of peace at home). For prevention or treatment of female orgasm disorders, attention to physical factors is not enough. Obtaining a comprehensive history about physical, psychological, relational and contextual dimensions of woman's life is necessary.

  15. A bio-inspired kinematic controller for obstacle avoidance during reaching tasks with real robots.

    PubMed

    Srinivasa, Narayan; Bhattacharyya, Rajan; Sundareswara, Rashmi; Lee, Craig; Grossberg, Stephen

    2012-11-01

    This paper describes a redundant robot arm that is capable of learning to reach for targets in space in a self-organized fashion while avoiding obstacles. Self-generated movement commands that activate correlated visual, spatial and motor information are used to learn forward and inverse kinematic control models while moving in obstacle-free space using the Direction-to-Rotation Transform (DIRECT). Unlike prior DIRECT models, the learning process in this work was realized using an online Fuzzy ARTMAP learning algorithm. The DIRECT-based kinematic controller is fault tolerant and can handle a wide range of perturbations such as joint locking and the use of tools despite not having experienced them during learning. The DIRECT model was extended based on a novel reactive obstacle avoidance direction (DIRECT-ROAD) model to enable redundant robots to avoid obstacles in environments with simple obstacle configurations. However, certain configurations of obstacles in the environment prevented the robot from reaching the target with purely reactive obstacle avoidance. To address this complexity, a self-organized process of mental rehearsals of movements was modeled, inspired by human and animal experiments on reaching, to generate plans for movement execution using DIRECT-ROAD in complex environments. These mental rehearsals or plans are self-generated by using the Fuzzy ARTMAP algorithm to retrieve multiple solutions for reaching each target while accounting for all the obstacles in its environment. The key aspects of the proposed novel controller were illustrated first using simple examples. Experiments were then performed on real robot platforms to demonstrate successful obstacle avoidance during reaching tasks in real-world environments. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Teachers' Stages of Concern about the Target-Oriented Curriculum.

    ERIC Educational Resources Information Center

    Cheung, Derek; Ng, Davis

    2000-01-01

    Investigates teachers' concerns about the Target-Oriented Curriculum (TOC) in Hong Kong (China). Finds that most teachers showed concern about the management of TOC (found in the third stage) and most were concerned with efficiency, time demands, organization, scheduling, and the best use of resources. Includes references. (CMK)

  17. Curriculum Reform in Mathematics and the Target Oriented Curriculum.

    ERIC Educational Resources Information Center

    Fung, Chun Ip

    1995-01-01

    Highlights issues and ideas in the reform of school mathematics curricula with reference to Australia, the United Kingdom, and the United States. Interprets the ideas set out in documents related to the Target Oriented Curriculum (TOC) initiative in Hong Kong. Discusses factors that hinder the implementation of the TOC. (DSK)

  18. Obstacle detectors for automated transit vehicles: A technoeconomic and market analysis

    NASA Technical Reports Server (NTRS)

    Lockerby, C. E.

    1979-01-01

    A search was conducted to identify the technical and economic characteristics of both NASA and nonNASA obstacle detectors. The findings, along with market information were compiled and analyzed for consideration by DOT and NASA in decisions about any future automated transit vehicle obstacle detector research, development, or applications project. Currently available obstacle detectors and systems under development are identified by type (sonic, capacitance, infrared/optical, guided radar, and probe contact) and compared with the three NASA devices selected as possible improvements or solutions to the problems in existing obstacle detection systems. Cost analyses and market forecasts individually for the AGT and AMTV markets are included.

  19. The Sensitivity Analysis for the Flow Past Obstacles Problem with Respect to the Reynolds Number

    PubMed Central

    Ito, Kazufumi; Li, Zhilin; Qiao, Zhonghua

    2013-01-01

    In this paper, numerical sensitivity analysis with respect to the Reynolds number for the flow past obstacle problem is presented. To carry out such analysis, at each time step, we need to solve the incompressible Navier-Stokes equations on irregular domains twice, one for the primary variables; the other is for the sensitivity variables with homogeneous boundary conditions. The Navier-Stokes solver is the augmented immersed interface method for Navier-Stokes equations on irregular domains. One of the most important contribution of this paper is that our analysis can predict the critical Reynolds number at which the vortex shading begins to develop in the wake of the obstacle. Some interesting experiments are shown to illustrate how the critical Reynolds number varies with different geometric settings. PMID:24910780

  20. The Sensitivity Analysis for the Flow Past Obstacles Problem with Respect to the Reynolds Number.

    PubMed

    Ito, Kazufumi; Li, Zhilin; Qiao, Zhonghua

    2012-02-01

    In this paper, numerical sensitivity analysis with respect to the Reynolds number for the flow past obstacle problem is presented. To carry out such analysis, at each time step, we need to solve the incompressible Navier-Stokes equations on irregular domains twice, one for the primary variables; the other is for the sensitivity variables with homogeneous boundary conditions. The Navier-Stokes solver is the augmented immersed interface method for Navier-Stokes equations on irregular domains. One of the most important contribution of this paper is that our analysis can predict the critical Reynolds number at which the vortex shading begins to develop in the wake of the obstacle. Some interesting experiments are shown to illustrate how the critical Reynolds number varies with different geometric settings.

  1. UAV formation control design with obstacle avoidance in dynamic three-dimensional environment.

    PubMed

    Chang, Kai; Xia, Yuanqing; Huang, Kaoli

    2016-01-01

    This paper considers the artificial potential field method combined with rotational vectors for a general problem of multi-unmanned aerial vehicle (UAV) systems tracking a moving target in dynamic three-dimensional environment. An attractive potential field is generated between the leader and the target. It drives the leader to track the target based on the relative position of them. The other UAVs in the formation are controlled to follow the leader by the attractive control force. The repulsive force affects among the UAVs to avoid collisions and distribute the UAVs evenly on the spherical surface whose center is the leader-UAV. Specific orders or positions of the UAVs are not required. The trajectories of avoidance obstacle can be obtained through two kinds of potential field with rotation vectors. Every UAV can choose the optimal trajectory to avoid the obstacle and reconfigure the formation after passing the obstacle. Simulations study on UAV are presented to demonstrate the effectiveness of proposed method.

  2. Obstacle Characterization in a Geocrowdsourced Accessibility System

    NASA Astrophysics Data System (ADS)

    Qin, H.; Aburizaiza, A. O.; Rice, R. M.; Paez, F.; Rice, M. T.

    2015-08-01

    Transitory obstacles - random, short-lived and unpredictable objects - are difficult to capture in any traditional mapping system, yet they have significant negative impacts on the accessibility of mobility- and visually-impaired individuals. These transitory obstacles include sidewalk obstructions, construction detours, and poor surface conditions. To identify these obstacles and assist the navigation of mobility- and visually- impaired individuals, crowdsourced mapping applications have been developed to harvest and analyze the volunteered obstacles reports from local students, faculty, staff, and residents. In this paper, we introduce a training program designed and implemented for recruiting and motivating contributors to participate in our geocrowdsourced accessibility system, and explore the quality of geocrowdsourced data with a comparative analysis methodology.

  3. The effects of platform motion and target orientation on the performance of trackball manipulation.

    PubMed

    Yau, Yi-Jan; Chao, Chin-Jung; Feng, Wen-Yang; Hwang, Sheue-Ling

    2011-08-01

    The trackball has been widely employed as a control/command input device on moving vehicles, but few studies have explored the effects of platform motion on its manipulation. Fewer still have considered this issue in designing the user interface and the arrangement of console location and orientation simultaneously. This work describes an experiment carried out to investigate the performance of trackball users on a simple point-and-click task in a motion simulator. By varying the orientation of onscreen targets, the effect of cursor movement direction on performance is investigated. The results indicate that the platform motion and target orientation both significantly affect the time required to point and click, but not the accuracy of target selection. The movement times were considerably longer under rolling and pitching motions and for targets located along the diagonal axes of the interface. Subjective evaluations carried out by the participants agree with these objective results. These findings could be used to optimise console and graphical menu design for use on maritime vessels. STATEMENT OF RELEVANCE: In military situations, matters of life or death may be decided in milliseconds. Any delay or error in classification and identification will thus affect the safety of the ship and its crew. This study demonstrates that performance of manipulating a trackball is affected by the platform motion and target orientation. The results of the present study can guide the arrangement of consoles and the design of trackball-based graphical user interfaces on maritime vessels.

  4. CytoSpectre: a tool for spectral analysis of oriented structures on cellular and subcellular levels.

    PubMed

    Kartasalo, Kimmo; Pölönen, Risto-Pekka; Ojala, Marisa; Rasku, Jyrki; Lekkala, Jukka; Aalto-Setälä, Katriina; Kallio, Pasi

    2015-10-26

    Orientation and the degree of isotropy are important in many biological systems such as the sarcomeres of cardiomyocytes and other fibrillar structures of the cytoskeleton. Image based analysis of such structures is often limited to qualitative evaluation by human experts, hampering the throughput, repeatability and reliability of the analyses. Software tools are not readily available for this purpose and the existing methods typically rely at least partly on manual operation. We developed CytoSpectre, an automated tool based on spectral analysis, allowing the quantification of orientation and also size distributions of structures in microscopy images. CytoSpectre utilizes the Fourier transform to estimate the power spectrum of an image and based on the spectrum, computes parameter values describing, among others, the mean orientation, isotropy and size of target structures. The analysis can be further tuned to focus on targets of particular size at cellular or subcellular scales. The software can be operated via a graphical user interface without any programming expertise. We analyzed the performance of CytoSpectre by extensive simulations using artificial images, by benchmarking against FibrilTool and by comparisons with manual measurements performed for real images by a panel of human experts. The software was found to be tolerant against noise and blurring and superior to FibrilTool when analyzing realistic targets with degraded image quality. The analysis of real images indicated general good agreement between computational and manual results while also revealing notable expert-to-expert variation. Moreover, the experiment showed that CytoSpectre can handle images obtained of different cell types using different microscopy techniques. Finally, we studied the effect of mechanical stretching on cardiomyocytes to demonstrate the software in an actual experiment and observed changes in cellular orientation in response to stretching. CytoSpectre, a versatile, easy

  5. Bi-stability in cooperative transport by ants in the presence of obstacles

    PubMed Central

    Pinkoviezky, Itai; Feinerman, Ofer

    2018-01-01

    To cooperatively carry large food items to the nest, individual ants conform their efforts and coordinate their motion. Throughout this expedition, collective motion is driven both by internal interactions between the carrying ants and a response to newly arrived informed ants that orient the cargo towards the nest. During the transport process, the carrying group must overcome obstacles that block their path to the nest. Here, we investigate the dynamics of cooperative transport, when the motion of the ants is frustrated by a linear obstacle that obstructs the motion of the cargo. The obstacle contains a narrow opening that serves as the only available passage to the nest, and through which single ants can pass but not with the cargo. We provide an analytical model for the ant-cargo system in the constrained environment that predicts a bi-stable dynamic behavior between an oscillatory mode of motion along the obstacle and a convergent mode of motion near the opening. Using both experiments and simulations, we show how for small cargo sizes, the system exhibits spontaneous transitions between these two modes of motion due to fluctuations in the applied force on the cargo. The bi-stability provides two possible problem solving strategies for overcoming the obstacle, either by attempting to pass through the opening, or take large excursions to circumvent the obstacle. PMID:29746457

  6. Bi-stability in cooperative transport by ants in the presence of obstacles.

    PubMed

    Ron, Jonathan E; Pinkoviezky, Itai; Fonio, Ehud; Feinerman, Ofer; Gov, Nir S

    2018-05-01

    To cooperatively carry large food items to the nest, individual ants conform their efforts and coordinate their motion. Throughout this expedition, collective motion is driven both by internal interactions between the carrying ants and a response to newly arrived informed ants that orient the cargo towards the nest. During the transport process, the carrying group must overcome obstacles that block their path to the nest. Here, we investigate the dynamics of cooperative transport, when the motion of the ants is frustrated by a linear obstacle that obstructs the motion of the cargo. The obstacle contains a narrow opening that serves as the only available passage to the nest, and through which single ants can pass but not with the cargo. We provide an analytical model for the ant-cargo system in the constrained environment that predicts a bi-stable dynamic behavior between an oscillatory mode of motion along the obstacle and a convergent mode of motion near the opening. Using both experiments and simulations, we show how for small cargo sizes, the system exhibits spontaneous transitions between these two modes of motion due to fluctuations in the applied force on the cargo. The bi-stability provides two possible problem solving strategies for overcoming the obstacle, either by attempting to pass through the opening, or take large excursions to circumvent the obstacle.

  7. The orientating reflex: the "targeting reaction" and "searchlight of attention".

    PubMed

    Sokolov, E N; Nezlina, N I; Polyanskii, V B; Evtikhin, D V

    2002-01-01

    A concept of the orientating reflex is presented, based on the principle of vector coding of cognitive and executive processes. The orientating reflex is a complex of orientating reactions of motor, autonomic, and subjective types, accentuating new and significant stimuli. Two main systems form the orientating reflex: the "targeting reaction" and the "searchlight of attention:" In the visual system, the targeting reaction ensures that the image of the object falls onto the fovea; this is mediated by involvement of premotor neurons which are excited by saccade command neurons in the superior colliculi. The "searchlight of attention" is activated as a result of resonance within the gamma frequency range, selectively enhancing cortical detectors and involving the reticular nucleus of the thalamus. Novelty signals arise in novelty neurons of the hippocampus. The synaptic weightings of neocortical detectors for hippocampal novelty neurons is initially characterized by high efficiency, which assigns a significant level of excitation of these neurons to the new stimulus. During repeated stimulation, the synaptic weightings of all the detectors representing a given stimulus decrease, with the result that the novelty signal becomes weaker. When the stimulus changes, it acts on other detectors, whose weightings for novelty neurons remain high, which strengthens the novelty signal. Decreases in the synaptic weightings on repetition of a standard stimulus form a trace of this stimulus in the novelty neurons - this is the "neural model of the stimulus." The novelty signal is determined by the non-concordance of the new stimulus with this "neural model," which is formed under the influence of the standard stimulus. The greater the difference between the new stimulus and the previously formed neural model, the stronger the novelty signal.

  8. A Mobile Robot Sonar System with Obstacle Avoidance.

    DTIC Science & Technology

    1994-03-01

    WITH OBSTACLE - AVOIDANCE __ by __ Patrick Gerard Byrne March 1994 Thesis Advisor : Yutaka Kanayama Approved for public release; distribution is...point p is on a line L whose normal has an orientation a and whose distance from the origin is r (Figure 5). This method has an advantage in expressing...sonar(FRONTR); Wine(&pl); while(hitl I >’- 100.0 11 hitl 1 - 0.0 ){ hitl I = sonar(FRONTR); I skipO; line(&p3); gat- robO (&posit 1); while(positl.x

  9. [Development of child mental health services in Lithuania: achievements and obstacles].

    PubMed

    Pūras, Dainius

    2002-01-01

    In 1990, political, economic and social changes in Lithuania introduced the possibility to develop for the first time in nations's history an effective and modern system of child mental health services. During the period between 1990 and 1995 a new model of services was developed in the Department of Social pediatrics and child psychiatry of Vilnius University. The model included development of child and adolescent psychiatric services, as well as early intervention services for infants and preschool children with developmental disabilities. The emphasis, following recommendations of WHO and existing international standards, was made on deinstitutionalization and development of family-oriented and community-based services, which have been ignored by previous system. In the first half of 90's of 20th century, new training programs for professionals were introduced, more than 50 methods of assessment, treatment and rehabilitation, new for Lithuanian clinical practice, were implemented, and a new model of services, including primary, secondary and tertiary level of prevention, was introduced in demonstration sites. However, during next phase of development, in 1997-2001, serious obstacles for replicating new approaches across the country, have been identified, which threatened successful implementation of the new model of services into everyday clinical practice. Analysis of obstacles, which are blocking development of new approaches in the field of child mental health, is presented in the article. The main obstacles, identified during analysis of socioeconomic context, planning and utilization of resources, running of the system of services and evaluation of outcomes, are as follows: lack of intersectorial cooperation between health, education and social welfare systems; strong tradition of discrimination of psychosocial interventions in funding schemes of health services; societal attitudes, which tend to discriminate and stigmatize marginal groups, including

  10. Reliability Analysis of Time to Complete the Obstacle Course Portion of the Load Effects Assessment Program (LEAP)

    DTIC Science & Technology

    2016-10-25

    TIME TO COMPLETE THE OBSTACLE COURSE PORTION OF THE LOAD EFFECTS ASSESSMENT PROGRAM (LEAP) by K. Blake Mitchell Jessica M. Batty Megan E...Approved OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for...2014 – June 2015 4. TITLE AND SUBTITLE RELIABILITY ANALYSIS OF TIME TO COMPLETE THE OBSTACLE COURSE PORTION OF THE LOAD EFFECTS ASSESSMENT PROGRAM

  11. Application of Optical Flow Sensors for Dead Reckoning, Heading Reference, Obstacle Detection, and Obstacle Avoidance

    DTIC Science & Technology

    2015-09-01

    OPTICAL FLOW SENSORS FOR DEAD RECKONING, HEADING REFERENCE, OBSTACLE DETECTION, AND OBSTACLE AVOIDANCE by Tarek M. Nejah September 2015...SENSORS FOR DEAD RECKONING, HEADING REFERENCE, OBSTACLE DETECTION, AND OBSTACLE AVOIDANCE 5. FUNDING NUMBERS 6. AUTHOR(S) Nejah, Tarek M. 7...DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) A novel approach for dead reckoning, heading reference, obstacle detection, and obstacle

  12. Target-oriented imaging of hydraulic fractures by applying the staining algorithm for downhole microseismic migration

    NASA Astrophysics Data System (ADS)

    Lin, Ye; Zhang, Haijiang; Jia, Xiaofeng

    2018-03-01

    For microseismic monitoring of hydraulic fracturing, microseismic migration can be used to image the fracture network with scattered microseismic waves. Compared with conventional microseismic location-based fracture characterization methods, microseismic migration can better constrain the stimulated reservoir volume regardless of the completeness of detected and located microseismic sources. However, the imaging results from microseismic migration may suffer from the contamination of other structures and thus the target fracture zones may not be illuminated properly. To solve this issue, in this study we propose a target-oriented staining algorithm for microseismic reverse-time migration. In the staining algorithm, the target area is first stained by constructing an imaginary velocity field and then a synchronized source wavefield only concerning the target structure is produced. As a result, a synchronized image from imaging with the synchronized source wavefield mainly contains the target structures. Synthetic tests based on a downhole microseismic monitoring system show that the target-oriented microseismic reverse-time migration method improves the illumination of target areas.

  13. Women’s orgasm obstacles: A qualitative study

    PubMed Central

    Nekoolaltak, Maryam; Keshavarz, Zohreh; Simbar, Masoumeh; Nazari, Ali Mohammad; Baghestani, Ahmad Reza

    2017-01-01

    Background: Woman’s orgasm plays a vital role in sexual compatibility and marital satisfaction. Orgasm in women is a learnable phenomenon that is influenced by several factors. Objective: The aim of this study is exploring obstacles to orgasm in Iranian married women. Materials and Methods: This qualitative study with directed content analysis approach was conducted in 2015-2016, on 20 Iranian married women who were individually interviewed at two medical clinics in Tehran, Iran. Results: Orgasm obstacles were explored in one category, 4 subcategories, and 25 codes. The main category was “Multidimensionality of women’s orgasm obstacles”. Subcategories and some codes included: Physical obstacles (wife’s or husband’s boredom, vaginal infection, insufficient vaginal lubrication), psychological obstacles (lack of sexual knowledge, shame, lack of concentration on sex due to household and children problems), relational obstacles (husband’s hurry, having a dispute and annoyance with spouse) and contextual obstacles (Irregular sleep hours, lack of privacy and inability to separate children’s bedroom from their parents, lack of peace at home). Conclusion: For prevention or treatment of female orgasm disorders, attention to physical factors is not enough. Obtaining a comprehensive history about physical, psychological, relational and contextual dimensions of woman’s life is necessary. PMID:29082366

  14. Particle Filtering for Obstacle Tracking in UAS Sense and Avoid Applications

    PubMed Central

    Moccia, Antonio

    2014-01-01

    Obstacle detection and tracking is a key function for UAS sense and avoid applications. In fact, obstacles in the flight path must be detected and tracked in an accurate and timely manner in order to execute a collision avoidance maneuver in case of collision threat. The most important parameter for the assessment of a collision risk is the Distance at Closest Point of Approach, that is, the predicted minimum distance between own aircraft and intruder for assigned current position and speed. Since assessed methodologies can cause some loss of accuracy due to nonlinearities, advanced filtering methodologies, such as particle filters, can provide more accurate estimates of the target state in case of nonlinear problems, thus improving system performance in terms of collision risk estimation. The paper focuses on algorithm development and performance evaluation for an obstacle tracking system based on a particle filter. The particle filter algorithm was tested in off-line simulations based on data gathered during flight tests. In particular, radar-based tracking was considered in order to evaluate the impact of particle filtering in a single sensor framework. The analysis shows some accuracy improvements in the estimation of Distance at Closest Point of Approach, thus reducing the delay in collision detection. PMID:25105154

  15. An algorithm for automatic target recognition using passive radar and an EKF for estimating aircraft orientation

    NASA Astrophysics Data System (ADS)

    Ehrman, Lisa M.

    2005-07-01

    Rather than emitting pulses, passive radar systems rely on "illuminators of opportunity," such as TV and FM radio, to illuminate potential targets. These systems are attractive since they allow receivers to operate without emitting energy, rendering them covert. Until recently, most of the research regarding passive radar has focused on detecting and tracking targets. This dissertation focuses on extending the capabilities of passive radar systems to include automatic target recognition. The target recognition algorithm described in this dissertation uses the radar cross section (RCS) of potential targets, collected over a short period of time, as the key information for target recognition. To make the simulated RCS as accurate as possible, the received signal model accounts for aircraft position and orientation, propagation losses, and antenna gain patterns. An extended Kalman filter (EKF) estimates the target's orientation (and uncertainty in the estimate) from velocity measurements obtained from the passive radar tracker. Coupling the aircraft orientation and state with the known antenna locations permits computation of the incident and observed azimuth and elevation angles. The Fast Illinois Solver Code (FISC) simulates the RCS of potential target classes as a function of these angles. Thus, the approximated incident and observed angles allow the appropriate RCS to be extracted from a database of FISC results. Using this process, the RCS of each aircraft in the target class is simulated as though each is executing the same maneuver as the target detected by the system. Two additional scaling processes are required to transform the RCS into a power profile (magnitude only) simulating the signal in the receiver. First, the RCS is scaled by the Advanced Refractive Effects Prediction System (AREPS) code to account for propagation losses that occur as functions of altitude and range. Then, the Numerical Electromagnetic Code (NEC2) computes the antenna gain pattern

  16. Formation of collisionless shocks in magnetized plasma interaction with kinetic-scale obstacles

    DOE PAGES

    Cruz, F.; Alves, E. P.; Bamford, R. A.; ...

    2017-02-06

    We investigate the formation of collisionless magnetized shocks triggered by the interaction between magnetized plasma flows and miniature-sized (order of plasma kinetic-scales) magnetic obstacles resorting to massively parallel, full particle-in-cell simulations, including the electron kinetics. The critical obstacle size to generate a compressed plasma region ahead of these objects is determined by independently varying the magnitude of the dipolar magnetic moment and the plasma magnetization. Here we find that the effective size of the obstacle depends on the relative orientation between the dipolar and plasma internal magnetic fields, and we show that this may be critical to form a shockmore » in small-scale structures. We also study the microphysics of the magnetopause in different magnetic field configurations in 2D and compare the results with full 3D simulations. Finally, we evaluate the parameter range where such miniature magnetized shocks can be explored in laboratory experiments.« less

  17. Explaining process orientation failure and success in health care--three case studies.

    PubMed

    Hellman, Stefan; Kastberg, Gustaf; Siverbo, Sven

    2015-01-01

    In order to improve cooperation and collaboration between units, clinics and departments, many health care organizations (HCOs) have introduced process orientation. Several studies indicate problems in realizing these ambitions. The purpose of this paper is to explain and understand the success and failure of process orientation in HCOs. The authors conducted three case studies and applied Actor-Network Theory as an analytic lens. The realization of process orientation is hindered by neglect or resistance from physicians, who find the process targets to be of low medical priority. However, the authors also see that medical priorities are no stable entities but are susceptible to negotiations. Over time, process organization, process mapping, process measurement activities and the acting of enroled actors may have impact on medical priorities. Contrary to previous research, the findings indicate that New Public Management may not be the main obstacle against processes, that accounting figures may not be hard to disregard and that the role of leadership is not paramount.

  18. [Educational obstacles in the everyday living of the nurse teacher's pedagogical practice].

    PubMed

    Rodrigues, Malvina Thaís Pacheco; Mendes Sobrinho, José Augusto de Carvalho

    2008-01-01

    University teaching emerges as a theme frequently discussed in the educational scene. This article aims to investigate the educational obstacles emerging in the everyday living of the pedagogical practice of the nurse teacher from the Nursing Graduation Course at UEPSI, wishing to subsidize the elaboration of proposals for overcoming of these obstacles. It is a study of qualitative approach with data collection, questionnaire and semi-structured interview and data analysis through content analysis. According to the analysis, it is clear that the educational obstacles relate to the teacher person, to the students and to the institution. Thus, an establishment of a continuing education program in the action-reflection-action perspective is proposed as a way of overcoming the obstacles.

  19. Obstacles to nutrition labeling in restaurants.

    PubMed

    Almanza, B A; Nelson, D; Chai, S

    1997-02-01

    This study determined the major obstacles that foodservices face regarding nutrition labeling. Survey questionnaire was conducted in May 1994. In addition to demographic questions, the directors were asked questions addressing willingness, current practices, and perceived obstacles related to nutrition labeling. Sixty-eight research and development directors of the largest foodservice corporations as shown in Restaurants & Institutions magazine's list of the top 400 largest foodservices (July 1993). P tests were used to determine significance within a group for the number of foodservices that were currently using nutrition labeling, perceived impact of nutrition labeling on sales, and perceived responsibility to add nutrition labels. Regression analysis was used to determine the importance of factors on willingness to label. Response rate was 45.3%. Most companies were neutral about their willingness to use nutrition labeling. Two thirds of the respondents were not currently using nutrition labels. Only one third thought that it was the foodservice's responsibility to provide such information. Several companies perceived that nutrition labeling would have a potentially negative effect on annual sales volume. Major obstacles were identified as menu or personnel related, rather than cost related. Menu-related obstacles included too many menu variations, limited space on the menu for labeling, and loss of flexibility in changing the menu. Personnel-related obstacles included difficulty in training employees to implement nutrition labeling, and not enough time for foodservice personnel to implement nutrition labeling. Numerous opportunities will be created for dietetics professionals in helping foodservices overcome these menu- or personnel-related obstacles.

  20. A biologically inspired neural net for trajectory formation and obstacle avoidance.

    PubMed

    Glasius, R; Komoda, A; Gielen, S C

    1996-06-01

    In this paper we present a biologically inspired two-layered neural network for trajectory formation and obstacle avoidance. The two topographically ordered neural maps consist of analog neurons having continuous dynamics. The first layer, the sensory map, receives sensory information and builds up an activity pattern which contains the optimal solution (i.e. shortest path without collisions) for any given set of current position, target positions and obstacle positions. Targets and obstacles are allowed to move, in which case the activity pattern in the sensory map will change accordingly. The time evolution of the neural activity in the second layer, the motor map, results in a moving cluster of activity, which can be interpreted as a population vector. Through the feedforward connections between the two layers, input of the sensory map directs the movement of the cluster along the optimal path from the current position of the cluster to the target position. The smooth trajectory is the result of the intrinsic dynamics of the network only. No supervisor is required. The output of the motor map can be used for direct control of an autonomous system in a cluttered environment or for control of the actuators of a biological limb or robot manipulator. The system is able to reach a target even in the presence of an external perturbation. Computer simulations of a point robot and a multi-joint manipulator illustrate the theory.

  1. Through the eyes of a bird: modelling visually guided obstacle flight

    PubMed Central

    Lin, Huai-Ti; Ros, Ivo G.; Biewener, Andrew A.

    2014-01-01

    Various flight navigation strategies for birds have been identified at the large spatial scales of migratory and homing behaviours. However, relatively little is known about close-range obstacle negotiation through cluttered environments. To examine obstacle flight guidance, we tracked pigeons (Columba livia) flying through an artificial forest of vertical poles. Interestingly, pigeons adjusted their flight path only approximately 1.5 m from the forest entry, suggesting a reactive mode of path planning. Combining flight trajectories with obstacle pole positions, we reconstructed the visual experience of the pigeons throughout obstacle flights. Assuming proportional–derivative control with a constant delay, we searched the relevant parameter space of steering gains and visuomotor delays that best explained the observed steering. We found that a pigeon's steering resembles proportional control driven by the error angle between the flight direction and the desired opening, or gap, between obstacles. Using this pigeon steering controller, we simulated obstacle flights and showed that pigeons do not simply steer to the nearest opening in the direction of flight or destination. Pigeons bias their flight direction towards larger visual gaps when making fast steering decisions. The proposed behavioural modelling method converts the obstacle avoidance behaviour into a (piecewise) target-aiming behaviour, which is better defined and understood. This study demonstrates how such an approach decomposes open-loop free-flight behaviours into components that can be independently evaluated. PMID:24812052

  2. Through the eyes of a bird: modelling visually guided obstacle flight.

    PubMed

    Lin, Huai-Ti; Ros, Ivo G; Biewener, Andrew A

    2014-07-06

    Various flight navigation strategies for birds have been identified at the large spatial scales of migratory and homing behaviours. However, relatively little is known about close-range obstacle negotiation through cluttered environments. To examine obstacle flight guidance, we tracked pigeons (Columba livia) flying through an artificial forest of vertical poles. Interestingly, pigeons adjusted their flight path only approximately 1.5 m from the forest entry, suggesting a reactive mode of path planning. Combining flight trajectories with obstacle pole positions, we reconstructed the visual experience of the pigeons throughout obstacle flights. Assuming proportional-derivative control with a constant delay, we searched the relevant parameter space of steering gains and visuomotor delays that best explained the observed steering. We found that a pigeon's steering resembles proportional control driven by the error angle between the flight direction and the desired opening, or gap, between obstacles. Using this pigeon steering controller, we simulated obstacle flights and showed that pigeons do not simply steer to the nearest opening in the direction of flight or destination. Pigeons bias their flight direction towards larger visual gaps when making fast steering decisions. The proposed behavioural modelling method converts the obstacle avoidance behaviour into a (piecewise) target-aiming behaviour, which is better defined and understood. This study demonstrates how such an approach decomposes open-loop free-flight behaviours into components that can be independently evaluated.

  3. Acting Diverse: Target Group Orientation as Key Competence in Engineering Education

    ERIC Educational Resources Information Center

    Ihsen, S.; Buschmeyer, A.

    2007-01-01

    International companies are recognised by equity between men and women as well as between other different groups (Diversity) as an economic factor and incorporate it into their company visions. Mixed teams are set up to design target group-oriented products, for example in automotive engineering. Therefore they need employees who represent the…

  4. Urban-area extraction from polarimetric SAR image using combination of target decomposition and orientation angle

    NASA Astrophysics Data System (ADS)

    Zou, Bin; Lu, Da; Wu, Zhilu; Qiao, Zhijun G.

    2016-05-01

    The results of model-based target decomposition are the main features used to discriminate urban and non-urban area in polarimetric synthetic aperture radar (PolSAR) application. Traditional urban-area extraction methods based on modelbased target decomposition usually misclassified ground-trunk structure as urban-area or misclassified rotated urbanarea as forest. This paper introduces another feature named orientation angle to improve urban-area extraction scheme for the accurate mapping in urban by PolSAR image. The proposed method takes randomness of orientation angle into account for restriction of urban area first and, subsequently, implements rotation angle to improve results that oriented urban areas are recognized as double-bounce objects from volume scattering. ESAR L-band PolSAR data of the Oberpfaffenhofen Test Site Area was used to validate the proposed algorithm.

  5. Strategies for obstacle avoidance during walking in the cat.

    PubMed

    Chu, Kevin M I; Seto, Sandy H; Beloozerova, Irina N; Marlinski, Vladimir

    2017-08-01

    Avoiding obstacles is essential for successful navigation through complex environments. This study aimed to clarify what strategies are used by a typical quadruped, the cat, to avoid obstacles during walking. Four cats walked along a corridor 2.5 m long and 25 or 15 cm wide. Obstacles, small round objects 2.5 cm in diameter and 1 cm in height, were placed on the floor in various locations. Movements of the paw were recorded with a motion capture and analysis system (Visualeyez, PTI). During walking in the wide corridor, cats' preferred strategy for avoiding a single obstacle was circumvention, during which the stride direction changed while stride duration and swing-to-stride duration ratio were preserved. Another strategy, stepping over the obstacle, was used during walking in the narrow corridor, when lateral deviations of walking trajectory were restricted. Stepping over the obstacle involved changes in two consecutive strides. The stride preceding the obstacle was shortened, and swing-to-stride ratio was reduced. The obstacle was negotiated in the next stride of increased height and normal duration and swing-to-stride ratio. During walking on a surface with multiple obstacles, both strategies were used. To avoid contact with the obstacle, cats placed the paw away from the object at a distance roughly equal to the diameter of the paw. During obstacle avoidance cats prefer to alter muscle activities without altering the locomotor rhythm. We hypothesize that a choice of the strategy for obstacle avoidance is determined by minimizing the complexity of neuro-motor processes required to achieve the behavioral goal. NEW & NOTEWORTHY In a study of feline locomotor behavior we found that the preferred strategy to avoid a small obstacle is circumvention. During circumvention, stride direction changes but length and temporal structure are preserved. Another strategy, stepping over the obstacle, is used in narrow walkways. During overstepping, two strides adjust. A stride

  6. Random walk of passive tracers among randomly moving obstacles.

    PubMed

    Gori, Matteo; Donato, Irene; Floriani, Elena; Nardecchia, Ilaria; Pettini, Marco

    2016-04-14

    This study is mainly motivated by the need of understanding how the diffusion behavior of a biomolecule (or even of a larger object) is affected by other moving macromolecules, organelles, and so on, inside a living cell, whence the possibility of understanding whether or not a randomly walking biomolecule is also subject to a long-range force field driving it to its target. By means of the Continuous Time Random Walk (CTRW) technique the topic of random walk in random environment is here considered in the case of a passively diffusing particle among randomly moving and interacting obstacles. The relevant physical quantity which is worked out is the diffusion coefficient of the passive tracer which is computed as a function of the average inter-obstacles distance. The results reported here suggest that if a biomolecule, let us call it a test molecule, moves towards its target in the presence of other independently interacting molecules, its motion can be considerably slowed down.

  7. Analysis of Core Stability Exercise Effect on the Physical and Psychological Function of Elderly Women Vulnerable to Falls during Obstacle Negotiation.

    PubMed

    Ko, Dae-Sik; Jung, Dae-In; Jeong, Mi-Ae

    2014-11-01

    [Purpose] The aim of the present study was to investigate the effects of core stability exercise (CSE) on the physical and psychological functions of elderly women while negotiating general obstacles. [Subjects and Methods] After allocating 10 elderly women each to the core stability training group and the control group, we carried out Performance-Oriented Mobility Assessment (POMA) and measured crossing velocity (CV), maximum vertical heel clearance (MVHC), and knee flexion angle for assessing physical performances. We evaluated depression and fear of falling for assessing psychological functions. [Results] Relative to the control group, the core stability training group showed statistically significant overall changes after the training session: an increase in POMA scores, faster CV, lower MVHC, and a decrease in knee flexion angle. Furthermore, depression and fear of falling decreased significantly. [Conclusion] CSE can have a positive effect on the improvement of physical and psychological performances of older women who are vulnerable to falls as they negotiate everyday obstacles.

  8. Measuring Sexual Orientation: A Review and Critique of U.S. Data Collection Efforts and Implications for Health Policy.

    PubMed

    Wolff, Margaret; Wells, Brooke; Ventura-DiPersia, Christina; Renson, Audrey; Grov, Christian

    The U.S. Department of Health and Human Services' (HHS) Healthy People 2020 goals sought to improve health outcomes among sexual minorities; HHS acknowledged that a dearth of sexual orientation items in federal and state health surveys obscured a broad understanding of sexual minority-related health disparities. The HHS 2011 data progression plan aimed to advance sexual orientation data collection efforts at the national level. Sexual orientation is a complex, multidimensional construct often composed of sexual identity, sexual attraction, and sexual behavior, thus posing challenges to its quantitative and practical measurement and analysis. In this review, we (a) present existing sexual orientation constructs; (b) evaluate current HHS sexual orientation data collection efforts; (c) review post-2011 data progression plan research on sexual minority health disparities, drawing on HHS survey data; (d) highlight the importance of and (e) identify obstacles to multidimensional sexual orientation measurement and analysis; and (f) discuss methods for multidimensional sexual orientation analysis and propose a matrix for addressing discordance/branchedness within these analyses. Multidimensional sexual orientation data collection and analysis would elucidate sexual minority-related health disparities, guide related health policies, and enhance population-based estimates of sexual minority individuals to steer health care practices.

  9. Foot strike patterns after obstacle clearance during running.

    PubMed

    Scholten, Shane D; Stergiou, Nicholas; Hreljac, Alan; Houser, Jeremy; Blanke, Daniel; Alberts, L Russell

    2002-01-01

    Running over obstacles of sufficient height requires heel strike (HS) runners to make a transition in landing strategy to a forefoot (FF) strike, resulting in similar ground reaction force patterns to those observed while landing from a jump. Identification of the biomechanical variables that distinguish between the landing strategies may offer some insight into the reasons that the transition occurs. The purpose of this study was to investigate the difference in foot strike patterns and kinetic parameters of heel strike runners between level running and running over obstacles of various heights. Ten heel strike subjects ran at their self-selected pace under seven different conditions: unperturbed running (no obstacle) and over obstacles of six different heights (10%, 12.5%, 15%, 17.5%, 20%, and 22.5% of their standing height). The obstacle was placed directly before a Kistler force platform. Repeated measures ANOVAs were performed on the subject means of selected kinetic parameters. The statistical analysis revealed significant differences (P < 0.004) for all of the parameters analyzed. The evaluation of the center of pressure and the ground reaction forces indicated that the foot strike patterns were affected by the increased obstacle height. Between the 12.5% and 15% obstacle conditions, the group response changed from a heel strike to a forefoot strike pattern. At height > 15%, the pattern was more closely related to the foot strike patterns found in jumping activities. This strategy change may represent a gait transition effected as a mechanism to protect against increased impact forces. Greater involvement of the ankle and the calf muscles could have assisted in attenuating the increased impact forces while maintaining speed after clearing the obstacle.

  10. Dynamic Obstacle Avoidance for Unmanned Underwater Vehicles Based on an Improved Velocity Obstacle Method

    PubMed Central

    Zhang, Wei; Wei, Shilin; Teng, Yanbin; Zhang, Jianku; Wang, Xiufang; Yan, Zheping

    2017-01-01

    In view of a dynamic obstacle environment with motion uncertainty, we present a dynamic collision avoidance method based on the collision risk assessment and improved velocity obstacle method. First, through the fusion optimization of forward-looking sonar data, the redundancy of the data is reduced and the position, size and velocity information of the obstacles are obtained, which can provide an accurate decision-making basis for next-step collision avoidance. Second, according to minimum meeting time and the minimum distance between the obstacle and unmanned underwater vehicle (UUV), this paper establishes the collision risk assessment model, and screens key obstacles to avoid collision. Finally, the optimization objective function is established based on the improved velocity obstacle method, and a UUV motion characteristic is used to calculate the reachable velocity sets. The optimal collision speed of UUV is searched in velocity space. The corresponding heading and speed commands are calculated, and outputted to the motion control module. The above is the complete dynamic obstacle avoidance process. The simulation results show that the proposed method can obtain a better collision avoidance effect in the dynamic environment, and has good adaptability to the unknown dynamic environment. PMID:29186878

  11. The didactic situation in geometry learning based on analysis of learning obstacles and learning trajectory

    NASA Astrophysics Data System (ADS)

    Sulistyowati, Fitria; Budiyono, Slamet, Isnandar

    2017-12-01

    This study aims to design a didactic situation based on the analysis of learning obstacles and learning trajectory on prism volume. The type of this research is qualitative and quantitative research with steps: analyzing the learning obstacles and learning trajectory, preparing the didactic situation, applying the didactic situation in the classroom, mean difference test of problem solving ability with t-test statistic. The subjects of the study were 8th grade junior high school students in Magelang 2016/2017 selected randomly from eight existing classes. The result of this research is the design of didactic situations that can be implemented in prism volume learning. The effectiveness of didactic situations that have been designed is shown by the mean difference test that is the problem solving ability of the students after the application of the didactic situation better than before the application. The didactic situation that has been generated is expected to be a consideration for teachers to design lessons that match the character of learners, classrooms and teachers themselves, so that the potential thinking of learners can be optimized to avoid the accumulation of learning obstacles.

  12. Orientation-crowding within contours.

    PubMed

    Glen, James C; Dakin, Steven C

    2013-07-15

    We examined how crowding (the breakdown of object recognition in the periphery caused by interference from "clutter") depends on the global arrangement of target and distracting flanker elements. Specifically we probed orientation discrimination using a near-vertical target Gabor flanked by two vertical distractor Gabors (one above and one below the target). By applying variable (opposite-sign) horizontal offsets to the positions of the two flankers we arranged the elements so that on some trials they formed contours with the target and on others they did not. While the presence of flankers generally elevated orientation discrimination thresholds for the target we observe maximal crowding not when flanker and targets were co-aligned but when a small spatial offset was applied to flanker location, so that contours formed between flanker and targets only when the target orientation was cued. We also report that observers' orientation judgments are biased, with target orientation appearing either attracted or repulsed by the global/contour orientation. A second experiment reveals that the sign of this effect is dependent both on observer and on eccentricity. In general, the magnitude of repulsion is reduced with eccentricity but whether this becomes attraction (of element orientation to contour orientation) is dependent on observer. We note however that across observers and eccentricities, the magnitude of repulsion correlates positively with the amount of release from crowding observed with co-aligned targets and flankers, supporting the notion of fluctuating bias as the basis for elevated crowding within contours.

  13. Identification and analysis of obstacles in bioterrorism preparedness and response

    NASA Astrophysics Data System (ADS)

    Sincavage, Suzanne Michele

    The focus of this study was to identify and analyze the obstacles to bioterrorism preparedness and response facing emergency management agencies and public authorities. In order to establish the limits of this discussion, the obstacles will examine a combined conceptual framework of public health, environmental security and social response. The interdisciplinary characteristics of this framework are ideal for addressing the issue of bioterrorism because of its simultaneous impact, which encompasses the complex interrelationships that pertain to public health and national security and social response. Based on a review of literature, the obstacles presented range from the absence of an effective surveillance system for biological terrorism related diseases to the inadequate training of first responders in bioterrorism preparedness and the difficult challenges of a mass casualty situation and the intense pressures associated with the crisis response. Furthermore, the impending reality of bioterrorism will further illustrate a close examination of the characteristics and management of three major biowarfare agents---anthrax, plague and smallpox. Finally, to provide a realistic understanding of the impact of bioterrorism, three case studies of actual events and two hypothetical scenarios will be discussed. Specifically, the discussion will provide the following three unconventional terrorist attacks: the recent anthrax attacks of 2001, the Aum Shinrikyo's attack of the Tokyo subway in 1995, and the Rajneeshees' use of salmonella poisoning in 1994. The inclusion of the hypothetical scenarios of two massive outbreaks of smallpox and anthrax will be presented to illuminate the seriousness and magnitude of the threat of bioterrorism and the probable consequences of failing to overcome the obstacles presented in this study. The importance of this research cannot be overemphasized, the threat is undeniably serious, and the potential for biological agents to cause devastating

  14. Assistive obstacle detection and navigation devices for vision-impaired users.

    PubMed

    Ong, S K; Zhang, J; Nee, A Y C

    2013-09-01

    Quality of life for the visually impaired is an urgent worldwide issue that needs to be addressed. Obstacle detection is one of the most important navigation tasks for the visually impaired. In this research, a novel range sensor placement scheme is proposed in this paper for the development of obstacle detection devices. Based on this scheme, two prototypes have been developed targeting at different user groups. This paper discusses the design issues, functional modules and the evaluation tests carried out for both prototypes. Implications for Rehabilitation Visual impairment problem is becoming more severe due to the worldwide ageing population. Individuals with visual impairment require assistance from assistive devices in daily navigation tasks. Traditional assistive devices that assist navigation may have certain drawbacks, such as the limited sensing range of a white cane. Obstacle detection devices applying the range sensor technology can identify road conditions with a higher sensing range to notify the users of potential dangers in advance.

  15. Horizon Based Orientation Estimation for Planetary Surface Navigation

    NASA Technical Reports Server (NTRS)

    Bouyssounouse, X.; Nefian, A. V.; Deans, M.; Thomas, A.; Edwards, L.; Fong, T.

    2016-01-01

    Planetary rovers navigate in extreme environments for which a Global Positioning System (GPS) is unavailable, maps are restricted to relatively low resolution provided by orbital imagery, and compass information is often lacking due to weak or not existent magnetic fields. However, an accurate rover localization is particularly important to achieve the mission success by reaching the science targets, avoiding negative obstacles visible only in orbital maps, and maintaining good communication connections with ground. This paper describes a horizon solution for precise rover orientation estimation. The detected horizon in imagery provided by the on board navigation cameras is matched with the horizon rendered over the existing terrain model. The set of rotation parameters (roll, pitch yaw) that minimize the cost function between the two horizon curves corresponds to the rover estimated pose.

  16. Mesoscale Thermodynamic Analysis of Atomic-Scale Dislocation-Obstacle Interactions Simulated by Molecular Dynamics

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

    Monet, Giath; Bacon, David J; Osetskiy, Yury N

    2010-01-01

    Given the time and length scales in molecular dynamics (MD) simulations of dislocation-defect interactions, quantitative MD results cannot be used directly in larger scale simulations or compared directly with experiment. A method to extract fundamental quantities from MD simulations is proposed here. The first quantity is a critical stress defined to characterise the obstacle resistance. This mesoscopic parameter, rather than the obstacle 'strength' designed for a point obstacle, is to be used for an obstacle of finite size. At finite temperature, our analyses of MD simulations allow the activation energy to be determined as a function of temperature. The resultsmore » confirm the proportionality between activation energy and temperature that is frequently observed by experiment. By coupling the data for the activation energy and the critical stress as functions of temperature, we show how the activation energy can be deduced at a given value of the critical stress.« less

  17. Design oriented structural analysis

    NASA Technical Reports Server (NTRS)

    Giles, Gary L.

    1994-01-01

    Desirable characteristics and benefits of design oriented analysis methods are described and illustrated by presenting a synoptic description of the development and uses of the Equivalent Laminated Plate Solution (ELAPS) computer code. ELAPS is a design oriented structural analysis method which is intended for use in the early design of aircraft wing structures. Model preparation is minimized by using a few large plate segments to model the wing box structure. Computational efficiency is achieved by using a limited number of global displacement functions that encompass all segments over the wing planform. Coupling with other codes is facilitated since the output quantities such as deflections and stresses are calculated as continuous functions over the plate segments. Various aspects of the ELAPS development are discussed including the analytical formulation, verification of results by comparison with finite element analysis results, coupling with other codes, and calculation of sensitivity derivatives. The effectiveness of ELAPS for multidisciplinary design application is illustrated by describing its use in design studies of high speed civil transport wing structures.

  18. Why Implementing History and Philosophy in School Science Education is a Challenge: An Analysis of Obstacles

    NASA Astrophysics Data System (ADS)

    Höttecke, Dietmar; Silva, Cibelle Celestino

    2011-03-01

    Teaching and learning with history and philosophy of science (HPS) has been, and continues to be, supported by science educators. While science education standards documents in many countries also stress the importance of teaching and learning with HPS, the approach still suffers from ineffective implementation in school science teaching. In order to better understand this problem, an analysis of the obstacles of implementing HPS into classrooms was undertaken. The obstacles taken into account were structured in four groups: 1. culture of teaching physics, 2. teachers' skills, epistemological and didactical attitudes and beliefs, 3. institutional framework of science teaching, and 4. textbooks as fundamental didactical support. Implications for more effective implementation of HPS are presented, taking the social nature of educational systems into account.

  19. Multiple groups of orientation-selective visual mechanisms underlying rapid orientated-line detection.

    PubMed Central

    Foster, D H; Westland, S

    1998-01-01

    Visual search for an edge or line element differing in orientation from a background of other edge or line elements can be performed rapidly and effortlessly. In this study, based on psychophysical measurements with ten human observers, threshold values of the angle between a target and background line elements were obtained as functions of background-element orientation, in brief masked displays. A repeated-loess analysis of the threshold functions suggested the existence of several groups of orientation-selective mechanisms contributing to rapid orientated-line detection; specifically, coarse, intermediate and fine mechanisms with preferred orientations spaced at angles of approximately 90 degrees, 35 degrees, and 10 degrees-25 degrees, respectively. The preferred orientations of coarse and some intermediate mechanisms coincided with the vertical or horizontal of the frontoparallel plane, but the preferred orientations of fine mechanisms varied randomly from observer to observer, possibly reflecting individual variations in neuronal sampling characteristics. PMID:9753784

  20. Robust obstacle detection for unmanned surface vehicles

    NASA Astrophysics Data System (ADS)

    Qin, Yueming; Zhang, Xiuzhi

    2018-03-01

    Obstacle detection is of essential importance for Unmanned Surface Vehicles (USV). Although some obstacles (e.g., ships, islands) can be detected by Radar, there are many other obstacles (e.g., floating pieces of woods, swimmers) which are difficult to be detected via Radar because these obstacles have low radar cross section. Therefore, detecting obstacle from images taken onboard is an effective supplement. In this paper, a robust vision-based obstacle detection method for USVs is developed. The proposed method employs the monocular image sequence captured by the camera on the USVs and detects obstacles on the sea surface from the image sequence. The experiment results show that the proposed scheme is efficient to fulfill the obstacle detection task.

  1. Perspectives on the Cultural Appropriacy of Hong Kong's Target-Oriented Curriculum (TOC) Initiative.

    ERIC Educational Resources Information Center

    Carless, David Robert

    1999-01-01

    Explores the impact of Chinese culture on the school curriculum in Hong Kong. Argues that the Target-Oriented Curriculum (TOC) transplanted from western-based concepts is not commensurate with the local Chinese cultural context, and therefore leads to many problems when being implemented in schools. (Author/VWL)

  2. Ravens, Corvus corax, follow gaze direction of humans around obstacles.

    PubMed Central

    Bugnyar, Thomas; Stöwe, Mareike; Heinrich, Bernd

    2004-01-01

    The ability to follow gaze (i.e. head and eye direction) has recently been shown for social mammals, particularly primates. In most studies, individuals could use gaze direction as a behavioural cue without understanding that the view of others may be different from their own. Here, we show that hand-raised ravens not only visually co-orient with the look-ups of a human experimenter but also reposition themselves to follow the experimenter's gaze around a visual barrier. Birds were capable of visual co-orientation already as fledglings but consistently tracked gaze direction behind obstacles not before six months of age. These results raise the possibility that sub-adult and adult ravens can project a line of sight for the other person into the distance. To what extent ravens may attribute mental significance to the visual behaviour of others is discussed. PMID:15306330

  3. Integrating obstacle avoidance, global path planning, visual cue detection, and landmark triangulation in a mobile robot

    NASA Astrophysics Data System (ADS)

    Kortenkamp, David; Huber, Marcus J.; Congdon, Clare B.; Huffman, Scott B.; Bidlack, Clint R.; Cohen, Charles J.; Koss, Frank V.; Raschke, Ulrich; Weymouth, Terry E.

    1993-05-01

    This paper describes the design and implementation of an integrated system for combining obstacle avoidance, path planning, landmark detection and position triangulation. Such an integrated system allows the robot to move from place to place in an environment, avoiding obstacles and planning its way out of traps, while maintaining its position and orientation using distinctive landmarks. The task the robot performs is to search a 22 m X 22 m arena for 10 distinctive objects, visiting each object in turn. This same task was recently performed by a dozen different robots at a competition in which the robot described in this paper finished first.

  4. Goal-oriented sensitivity analysis for lattice kinetic Monte Carlo simulations

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

    Arampatzis, Georgios, E-mail: garab@math.uoc.gr; Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003; Katsoulakis, Markos A., E-mail: markos@math.umass.edu

    2014-03-28

    In this paper we propose a new class of coupling methods for the sensitivity analysis of high dimensional stochastic systems and in particular for lattice Kinetic Monte Carlo (KMC). Sensitivity analysis for stochastic systems is typically based on approximating continuous derivatives with respect to model parameters by the mean value of samples from a finite difference scheme. Instead of using independent samples the proposed algorithm reduces the variance of the estimator by developing a strongly correlated-“coupled”- stochastic process for both the perturbed and unperturbed stochastic processes, defined in a common state space. The novelty of our construction is that themore » new coupled process depends on the targeted observables, e.g., coverage, Hamiltonian, spatial correlations, surface roughness, etc., hence we refer to the proposed method as goal-oriented sensitivity analysis. In particular, the rates of the coupled Continuous Time Markov Chain are obtained as solutions to a goal-oriented optimization problem, depending on the observable of interest, by considering the minimization functional of the corresponding variance. We show that this functional can be used as a diagnostic tool for the design and evaluation of different classes of couplings. Furthermore, the resulting KMC sensitivity algorithm has an easy implementation that is based on the Bortz–Kalos–Lebowitz algorithm's philosophy, where events are divided in classes depending on level sets of the observable of interest. Finally, we demonstrate in several examples including adsorption, desorption, and diffusion Kinetic Monte Carlo that for the same confidence interval and observable, the proposed goal-oriented algorithm can be two orders of magnitude faster than existing coupling algorithms for spatial KMC such as the Common Random Number approach. We also provide a complete implementation of the proposed sensitivity analysis algorithms, including various spatial KMC examples, in a

  5. Vision Based Obstacle Detection in Uav Imaging

    NASA Astrophysics Data System (ADS)

    Badrloo, S.; Varshosaz, M.

    2017-08-01

    Detecting and preventing incidence with obstacles is crucial in UAV navigation and control. Most of the common obstacle detection techniques are currently sensor-based. Small UAVs are not able to carry obstacle detection sensors such as radar; therefore, vision-based methods are considered, which can be divided into stereo-based and mono-based techniques. Mono-based methods are classified into two groups: Foreground-background separation, and brain-inspired methods. Brain-inspired methods are highly efficient in obstacle detection; hence, this research aims to detect obstacles using brain-inspired techniques, which try to enlarge the obstacle by approaching it. A recent research in this field, has concentrated on matching the SIFT points along with, SIFT size-ratio factor and area-ratio of convex hulls in two consecutive frames to detect obstacles. This method is not able to distinguish between near and far obstacles or the obstacles in complex environment, and is sensitive to wrong matched points. In order to solve the above mentioned problems, this research calculates the dist-ratio of matched points. Then, each and every point is investigated for Distinguishing between far and close obstacles. The results demonstrated the high efficiency of the proposed method in complex environments.

  6. Do characteristics of a stationary obstacle lead to adjustments in obstacle stepping strategies?

    PubMed

    Worden, Timothy A; De Jong, Audrey F; Vallis, Lori Ann

    2016-01-01

    Navigating cluttered and complex environments increases the risk of falling. To decrease this risk, it is important to understand the influence of obstacle visual cues on stepping parameters, however the specific obstacle characteristics that have the greatest influence on avoidance strategies is still under debate. The purpose of the current work is to provide further insight on the relationship between obstacle appearance in the environment and modulation of stepping parameters. Healthy young adults (N=8) first stepped over an obstacle with one visible top edge ("floating"; 8 trials) followed by trials where experimenters randomly altered the location of a ground reference object to one of 7 different positions (8 trials per location), which ranged from 6cm in front of, directly under, or up to 6cm behind the floating obstacle (at 2cm intervals). Mean take-off and landing distance as well as minimum foot clearance values were unchanged across different positions of the ground reference object; a consistent stepping trajectory was observed for all experimental conditions. Contrary to our hypotheses, results of this study indicate that ground based visual cues are not essential for the planning of stepping and clearance strategies. The simultaneous presentation of both floating and ground based objects may have provided critical information that lead to the adoption of a consistent strategy for clearing the top edge of the obstacle. The invariant foot placement observed here may be an appropriate stepping strategy for young adults, however this may not be the case across the lifespan or in special populations. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. The analysis of selected orientation methods of architectural objects' scans

    NASA Astrophysics Data System (ADS)

    Markiewicz, Jakub S.; Kajdewicz, Irmina; Zawieska, Dorota

    2015-05-01

    The terrestrial laser scanning is commonly used in different areas, inter alia in modelling architectural objects. One of the most important part of TLS data processing is scans registration. It significantly affects the accuracy of generation of high resolution photogrammetric documentation. This process is time consuming, especially in case of a large number of scans. It is mostly based on an automatic detection and a semi-automatic measurement of control points placed on the object. In case of the complicated historical buildings, sometimes it is forbidden to place survey targets on an object or it may be difficult to distribute survey targets in the optimal way. Such problems encourage the search for the new methods of scan registration which enable to eliminate the step of placing survey targets on the object. In this paper the results of target-based registration method are presented The survey targets placed on the walls of historical chambers of the Museum of King Jan III's Palace at Wilanów and on the walls of ruins of the Bishops Castle in Iłża were used for scan orientation. Several variants of orientation were performed, taking into account different placement and different number of survey marks. Afterwards, during next research works, raster images were generated from scans and the SIFT and SURF algorithms for image processing were used to automatically search for corresponding natural points. The case of utilisation of automatically identified points for TLS data orientation was analysed. The results of both methods for TLS data registration were summarized and presented in numerical and graphical forms.

  8. Accuracy of saccades to remembered targets as a function of body orientation in space

    NASA Technical Reports Server (NTRS)

    Vogelstein, Joshua T.; Snyder, Lawrence H.; Angelaki, Dora E.

    2003-01-01

    A vertical asymmetry in memory-guided saccadic eye movements has been previously demonstrated in humans and in rhesus monkeys. In the upright orientation, saccades generally land several degrees above the target. The origin of this asymmetry has remained unknown. In this study, we investigated whether the asymmetry in memory saccades is dependent on body orientation in space. Thus animals performed memory saccades in four different body orientations: upright, left-side-down (LSD), right-side-down (RSD), and supine. Data in all three rhesus monkeys confirm previous observations regarding a significant upward vertical asymmetry. Saccade errors made from LSD and RSD postures were partitioned into components made along the axis of gravity and along the vertical body axis. Up/down asymmetry persisted only in body coordinates but not in gravity coordinates. However, this asymmetry was generally reduced in tilted positions. Therefore the upward bias seen in memory saccades is egocentric although orientation in space might play a modulatory role.

  9. Numerical investigation on layout optimization of obstacles in a three-dimensional passive micromixer.

    PubMed

    Chen, Xueye; Zhao, Zhongyi

    2017-04-29

    This paper aims at layout optimization design of obstacles in a three-dimensional T-type micromixer. Numerical analysis shows that the direction of flow velocity change constantly due to the obstacles blocking, which produces the chaotic convection and increases species mixing effectively. The orthogonal experiment method was applied for determining the effects of some key parameters on mixing efficiency. The weights in the order are: height of obstacles > geometric shape > symmetry = number of obstacles. Based on the optimized results, a multi-units obstacle micromixer was designed. Compared with T-type micromixer, the multi-units obstacle micromixer is more efficient, and more than 90% mixing efficiency were obtained for a wide range of peclet numbers. It can be demonstrated that the presented optimal design method of obstacles layout in three-dimensional microchannels is a simple and effective technology to improve species mixing in microfluidic devices. The obstacles layout methodology has the potential for applications in chemical engineering and bioengineering. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. The Effects of Shoe Traction and Obstacle Height on Lower Extremity Coordination Dynamics during Walking

    PubMed Central

    Decker, Leslie; Houser, Jeremy J.; Noble, John M.; Karst, Gregory M.; Stergiou, Nicholas

    2009-01-01

    This study aims to investigate the effects of shoe traction and obstacle height on lower extremity relative phase dynamics (analysis of intralimb coordination) during walking to better understand the mechanisms employed to avoid slippage following obstacle clearance. Ten participants walked at a self-selected pace during eight conditions: four obstacle heights (0%, 10%, 20%, and 40% of limb length) while wearing two pairs of shoes (low and high traction). A coordination analysis was used and phasing relationships between lower extremity segments were examined. The results demonstrated that significant behavioral changes were elicited under varied obstacle heights and frictional conditions. Both decreasing shoe traction and increasing obstacle height resulted in a more in-phase relationship between the interacting lower limb segments. The higher the obstacle and the lower the shoe traction, the more unstable the system became. These changes in phasing relationship and variability are indicators of alterations in coordinative behavior, which if pushed further may have lead to falling. PMID:19187929

  11. Obstacles to integrated pest management adoption in developing countries

    PubMed Central

    Parsa, Soroush; Morse, Stephen; Bonifacio, Alejandro; Chancellor, Timothy C. B.; Condori, Bruno; Crespo-Pérez, Verónica; Hobbs, Shaun L. A.; Kroschel, Jürgen; Ba, Malick N.; Rebaudo, François; Sherwood, Stephen G.; Vanek, Steven J.; Faye, Emile; Herrera, Mario A.; Dangles, Olivier

    2014-01-01

    Despite its theoretical prominence and sound principles, integrated pest management (IPM) continues to suffer from anemic adoption rates in developing countries. To shed light on the reasons, we surveyed the opinions of a large and diverse pool of IPM professionals and practitioners from 96 countries by using structured concept mapping. The first phase of this method elicited 413 open-ended responses on perceived obstacles to IPM. Analysis of responses revealed 51 unique statements on obstacles, the most frequent of which was “insufficient training and technical support to farmers.” Cluster analyses, based on participant opinions, grouped these unique statements into six themes: research weaknesses, outreach weaknesses, IPM weaknesses, farmer weaknesses, pesticide industry interference, and weak adoption incentives. Subsequently, 163 participants rated the obstacles expressed in the 51 unique statements according to importance and remediation difficulty. Respondents from developing countries and high-income countries rated the obstacles differently. As a group, developing-country respondents rated “IPM requires collective action within a farming community” as their top obstacle to IPM adoption. Respondents from high-income countries prioritized instead the “shortage of well-qualified IPM experts and extensionists.” Differential prioritization was also evident among developing-country regions, and when obstacle statements were grouped into themes. Results highlighted the need to improve the participation of stakeholders from developing countries in the IPM adoption debate, and also to situate the debate within specific regional contexts. PMID:24567400

  12. An Analysis of Group-Oriented Contingencies and Associated Side Effects in Preschool Children

    ERIC Educational Resources Information Center

    Payne, Steven W.; Dozier, Claudia L.; Briggs, Adam M.; Newquist, Matthew H.

    2017-01-01

    Group-oriented contingencies are arranged to target the behavior of a group of people simultaneously. Overall, group-oriented contingencies have been shown to be effective in both decreasing problem behavior and increasing appropriate behavior. However, results are mixed regarding which type(s) of group-oriented contingency is most effective for…

  13. Postdictive modulation of visual orientation.

    PubMed

    Kawabe, Takahiro

    2012-01-01

    The present study investigated how visual orientation is modulated by subsequent orientation inputs. Observers were presented a near-vertical Gabor patch as a target, followed by a left- or right-tilted second Gabor patch as a distracter in the spatial vicinity of the target. The task of the observers was to judge whether the target was right- or left-tilted (Experiment 1) or whether the target was vertical or not (Supplementary experiment). The judgment was biased toward the orientation of the distracter (the postdictive modulation of visual orientation). The judgment bias peaked when the target and distracter were temporally separated by 100 ms, indicating a specific temporal mechanism for this phenomenon. However, when the visibility of the distracter was reduced via backward masking, the judgment bias disappeared. On the other hand, the low-visibility distracter could still cause a simultaneous orientation contrast, indicating that the distracter orientation is still processed in the visual system (Experiment 2). Our results suggest that the postdictive modulation of visual orientation stems from spatiotemporal integration of visual orientation on the basis of a slow feature matching process.

  14. [A semimicroquality evaluation method on Panax notoginseng and its application in analysis of continuous cropping obstacles research samples].

    PubMed

    Cao, Yi; Wang, Chao-Qun; Xu, Feng; Jia, Xiu-Hong; Liu, Guang-Xue; Yang, Sheng-Chao; Long, Guang-Qiang; Chen, Zhong-Jian; Wei, Fu-Zhou; Yang, Shao-Zhou; Fukuda, Kozo; Wang, Xuan; Cai, Shao-Qing

    2016-10-01

    Panax notoginseng is a commonly used traditional Chinese medicine with blood activating effect while has continuous cropping obstacle problem in planting process. In present study, a semimicroextraction method with water-saturated n-butanol on 0.1 g notoginseng sample was established with good repeatability (RSD<2.5%) and 9.6%-20.6% higher extraction efficiency of seven saponins than the conventional method. A total of 16 characteristic peaks were identified by LC-MS-IT-TOF, including eight 20(S)-protopanaxatriol (PPT) type saponins and eight 20(S)-protopanaxadiol (PPD) type saponins. The established method was utilized to evaluate the quality of notoginseng samples cultivated by manual intervened methods to overcome continuous cropping obstacles.As a result, HPLC fingerprint similarity, content of Fa and ratio of notoginsenoside K and notoginsenoside Fa (N-K/Fa) were found out to be as valuatable markers of the quality of samples in continuous cropping obstacle research, of which N-K/Fa could also be applied to the analysis of notoginseng samples with different growth years.Notoginseng samples with continuous cropping obstacle had HPLC fingerprint similarity lower than 0.87, in consistent with normal sample, and had significant lower content of notoginsenoside Fa and significant higher N-K/Fa (2.35-4.74) than normal group (0.45-1.33). All samples in the first group with manual intervention showed high similarity with normal group (>0.87), similar content of common peaks and N-K/Fa (0.42-2.06). The content of notoginsenoside K in the second group with manual intervention was higher than normal group. All samples except two displayed similarity higher than 0.87 and possessed content of 16 saponins close to normal group. The result showed that notoginseng samples with continuous cropping obstacle had lower quality than normal sample. And manual intervened methods could improve their quality in different levels.The method established in this study was simple, fast and

  15. Depletion forces on circular and elliptical obstacles induced by active matter

    NASA Astrophysics Data System (ADS)

    Leite, L. R.; Lucena, D.; Potiguar, F. Q.; Ferreira, W. P.

    2016-12-01

    Depletion forces exerted by self-propelled particles on circular and elliptical passive objects are studied using numerical simulations. We show that a bath of active particles can induce repulsive and attractive forces which are sensitive to the shape and orientation of the passive objects (either horizontal or vertical ellipses). The resultant force on the passive objects due to the active particles is studied as a function of the shape and orientation of the passive objects, magnitude of the angular noise, and distance between the passive objects. By increasing the distance between obstacles the magnitude of the repulsive depletion force increases, as long as such a distance is less than one active particle diameter. For longer distances, the magnitude of the force always decreases with increasing distance. We also found that attractive forces may arise for vertical ellipses at high enough area fraction.

  16. Depletion forces on circular and elliptical obstacles induced by active matter.

    PubMed

    Leite, L R; Lucena, D; Potiguar, F Q; Ferreira, W P

    2016-12-01

    Depletion forces exerted by self-propelled particles on circular and elliptical passive objects are studied using numerical simulations. We show that a bath of active particles can induce repulsive and attractive forces which are sensitive to the shape and orientation of the passive objects (either horizontal or vertical ellipses). The resultant force on the passive objects due to the active particles is studied as a function of the shape and orientation of the passive objects, magnitude of the angular noise, and distance between the passive objects. By increasing the distance between obstacles the magnitude of the repulsive depletion force increases, as long as such a distance is less than one active particle diameter. For longer distances, the magnitude of the force always decreases with increasing distance. We also found that attractive forces may arise for vertical ellipses at high enough area fraction.

  17. The Use of Object-Oriented Analysis Methods in Surety Analysis

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

    Craft, Richard L.; Funkhouser, Donald R.; Wyss, Gregory D.

    1999-05-01

    Object-oriented analysis methods have been used in the computer science arena for a number of years to model the behavior of computer-based systems. This report documents how such methods can be applied to surety analysis. By embodying the causality and behavior of a system in a common object-oriented analysis model, surety analysts can make the assumptions that underlie their models explicit and thus better communicate with system designers. Furthermore, given minor extensions to traditional object-oriented analysis methods, it is possible to automatically derive a wide variety of traditional risk and reliability analysis methods from a single common object model. Automaticmore » model extraction helps ensure consistency among analyses and enables the surety analyst to examine a system from a wider variety of viewpoints in a shorter period of time. Thus it provides a deeper understanding of a system's behaviors and surety requirements. This report documents the underlying philosophy behind the common object model representation, the methods by which such common object models can be constructed, and the rules required to interrogate the common object model for derivation of traditional risk and reliability analysis models. The methodology is demonstrated in an extensive example problem.« less

  18. Efficiency analysis of a multiple axle vehicle with hydrostatic transmission overcoming obstacles

    NASA Astrophysics Data System (ADS)

    Comellas, M.; Pijuan, J.; Nogués, M.; Roca, J.

    2018-01-01

    Transmission configurations in off-road vehicles with multiple driven axles can be a determining factor in the obstacle surmounting capacity and also in the vehicle efficiency. An off-road articulated vehicle with four driven axles, four bogies and two modules has been considered for the global hydrostatic transmission efficiency analysis and for the vehicle functional efficiency analysis. The power flow through the transmission system has been quantified from the combustion engine shaft to each axle of the wheels. It has been done for different the operating conditions and taking into account the wheel-terrain interaction and the transmission configuration, that could lead to a forced slippage of some of the wheels. Results show the influence of the different wheels' requirements, the transmission configuration limitations and the considered control strategy on the global transmission and vehicle functional efficiencies.

  19. Negative obstacle detection by thermal signature

    NASA Technical Reports Server (NTRS)

    Matthies, Larry; Rankin, A.

    2003-01-01

    Detecting negative obstacles (ditches, potholes, and other depressions) is one of the most difficult problems in perception for autonomous, off-road navigation. Past work has largely relied on range imagery, because that is based on the geometry of the obstacle, is largely insensitive to illumination variables, and because there have not been other reliable alternatives. However, the visible aspect of negative obstacles shrinks rapidly with range, making them impossible to detect in time to avoid them at high speed. To relive this problem, we show that the interiors of negative obstacles generally remain warmer than the surrounding terrain throughout the night, making thermal signature a stable property for night-time negative obstacle detection. Experimental results to date have achieved detection distances 45% greater by using thermal signature than by using range data alone. Thermal signature is the first known observable with potential to reveal a deep negative obstacle without actually seeing far into it. Modeling solar illumination has potential to extend the usefulness of thermal signature through daylight hours.

  20. Cascading a systolic array and a feedforward neural network for navigation and obstacle avoidance using potential fields

    NASA Technical Reports Server (NTRS)

    Plumer, Edward S.

    1991-01-01

    A technique is developed for vehicle navigation and control in the presence of obstacles. A potential function was devised that peaks at the surface of obstacles and has its minimum at the proper vehicle destination. This function is computed using a systolic array and is guaranteed not to have local minima. A feedfoward neural network is then used to control the steering of the vehicle using local potential field information. In this case, the vehicle is a trailer truck backing up. Previous work has demonstrated the capability of a neural network to control steering of such a trailer truck backing to a loading platform, but without obstacles. Now, the neural network was able to learn to navigate a trailer truck around obstacles while backing toward its destination. The network is trained in an obstacle free space to follow the negative gradient of the field, after which the network is able to control and navigate the truck to its target destination in a space of obstacles which may be stationary or movable.

  1. Apparent motion perception in lower limb amputees with phantom sensations: "obstacle shunning" and "obstacle tolerance".

    PubMed

    Saetta, Gianluca; Grond, Ilva; Brugger, Peter; Lenggenhager, Bigna; Tsay, Anthony J; Giummarra, Melita J

    2018-03-21

    Phantom limbs are the phenomenal persistence of postural and sensorimotor features of an amputated limb. Although immaterial, their characteristics can be modulated by the presence of physical matter. For instance, the phantom may disappear when its phenomenal space is invaded by objects ("obstacle shunning"). Alternatively, "obstacle tolerance" occurs when the phantom is not limited by the law of impenetrability and co-exists with physical objects. Here we examined the link between this under-investigated aspect of phantom limbs and apparent motion perception. The illusion of apparent motion of human limbs involves the perception that a limb moves through or around an object, depending on the stimulus onset asynchrony (SOA) for the two images. Participants included 12 unilateral lower limb amputees matched for obstacle shunning (n = 6) and obstacle tolerance (n = 6) experiences, and 14 non-amputees. Using multilevel linear models, we replicated robust biases for short perceived trajectories for short SOA (moving through the object), and long trajectories (circumventing the object) for long SOAs in both groups. Importantly, however, amputees with obstacle shunning perceived leg stimuli to predominantly move through the object, whereas amputees with obstacle tolerance perceived leg stimuli to predominantly move around the object. That is, in people who experience obstacle shunning, apparent motion perception of lower limbs was not constrained to the laws of impenetrability (as the phantom disappears when invaded by objects), and legs can therefore move through physical objects. Amputees who experience obstacle tolerance, however, had stronger solidity constraints for lower limb apparent motion, perhaps because they must avoid co-location of the phantom with physical objects. Phantom limb experience does, therefore, appear to be modulated by intuitive physics, but not in the same way for everyone. This may have important implications for limb experience post

  2. Gas turbine system simulation: An object-oriented approach

    NASA Technical Reports Server (NTRS)

    Drummond, Colin K.; Follen, Gregory J.; Putt, Charles W.

    1993-01-01

    A prototype gas turbine engine simulation has been developed that offers a generalized framework for the simulation of engines subject to steady-state and transient operating conditions. The prototype is in preliminary form, but it successfully demonstrates the viability of an object-oriented approach for generalized simulation applications. Although object oriented programming languages are-relative to FORTRAN-somewhat austere, it is proposed that gas turbine simulations of an interdisciplinary nature will benefit significantly in terms of code reliability, maintainability, and manageability. This report elucidates specific gas turbine simulation obstacles that an object-oriented framework can overcome and describes the opportunity for interdisciplinary simulation that the approach offers.

  3. Exploring performance obstacles of intensive care nurses.

    PubMed

    Gurses, Ayse P; Carayon, Pascale

    2009-05-01

    High nursing workload, poor patient safety, and poor nursing quality of working life (QWL) are major issues in intensive care units (ICUs). Characteristics of the ICU and performance obstacles may contribute to these issues. The goal of this study was to comprehensively identify the performance obstacles perceived by ICU nurses. We used a qualitative research design and conducted semi-structured interviews with 15 ICU nurses of a medical-surgical ICU. Based on this qualitative study and a previously reported quantitative study, we identified seven main types of performance obstacles experienced by ICU nurses. Obstacles related to the physical environment (e.g., noise, amount of space), family relations (e.g., distractions caused by family, lack of time to spend with family), and equipment (e.g., unavailability, misplacement) were the most frequently experienced performance obstacles. The qualitative interview data provided rich information regarding the factors contributing to the performance obstacles. Overall, ICU nurses experience a variety of performance obstacles in their work on a daily basis. Future research is needed to understand the impact of performance obstacles on nursing workload, nursing QWL, and quality and safety of care.

  4. Achieving serum urate targets in gout: an audit in a gout-oriented rheumatology practice.

    PubMed

    Corbett, Elizabeth J M; Pentony, Peta; McGill, Neil W

    2017-07-01

    To assess the proportion of patients with gout who achieve target serum urate levels, the drug regime required and the reasons for failing to do so. We reviewed the files of all patients with gout who presented to a gout-oriented rheumatology practice between January 2010 and September 2014. Two hundred and thirty patients agreed to commence urate lowering therapy (ULT); 73% achieved their urate target, including 74% with non-tophaceous gout (target ≤ 0.36 mmol/L) and 71% with tophi (target ≤ 0.30 mmol/L). Of the 62 who failed to reach target, in 61 it was due to non-adherence and in one due to inefficacy. Adherence remains the major challenge to successful long-term gout management. © 2017 Asia Pacific League of Associations for Rheumatology and John Wiley & Sons Australia, Ltd.

  5. A novel artificial immune algorithm for spatial clustering with obstacle constraint and its applications.

    PubMed

    Sun, Liping; Luo, Yonglong; Ding, Xintao; Zhang, Ji

    2014-01-01

    An important component of a spatial clustering algorithm is the distance measure between sample points in object space. In this paper, the traditional Euclidean distance measure is replaced with innovative obstacle distance measure for spatial clustering under obstacle constraints. Firstly, we present a path searching algorithm to approximate the obstacle distance between two points for dealing with obstacles and facilitators. Taking obstacle distance as similarity metric, we subsequently propose the artificial immune clustering with obstacle entity (AICOE) algorithm for clustering spatial point data in the presence of obstacles and facilitators. Finally, the paper presents a comparative analysis of AICOE algorithm and the classical clustering algorithms. Our clustering model based on artificial immune system is also applied to the case of public facility location problem in order to establish the practical applicability of our approach. By using the clone selection principle and updating the cluster centers based on the elite antibodies, the AICOE algorithm is able to achieve the global optimum and better clustering effect.

  6. Dynamics of spiral waves rotating around an obstacle and the existence of a minimal obstacle

    NASA Astrophysics Data System (ADS)

    Gao, Xiang; Feng, Xia; Li, Teng-Chao; Qu, Shixian; Wang, Xingang; Zhang, Hong

    2017-05-01

    Pinning of vortices by obstacles plays an important role in various systems. In the heart, anatomical reentry is created when a vortex, also known as the spiral wave, is pinned to an anatomical obstacle, leading to a class of physiologically very important arrhythmias. Previous analyses of its dynamics and instability provide fine estimates in some special circumstances, such as large obstacles or weak excitabilities. Here, to expand theoretical analyses to all circumstances, we propose a general theory whose results quantitatively agree with direct numerical simulations. In particular, when obstacles are small and pinned spiral waves are destabilized, an accurate explanation of the instability in two-dimensional media is provided by the usage of a mapping rule and dimension reduction. The implications of our results are to better understand the mechanism of arrhythmia and thus improve its early prevention.

  7. [Obstacles perceived by nurses for evidence-based practice: a qualitative study].

    PubMed

    Sánchez-García, Inmaculada; López-Medina, Isabel M; Pancorbo-Hidalgo, Pedro L

    2013-01-01

    To examine the obstacles perceived by nurses to implement an evidence-based clinical practice. A qualitative study through semi-structured interviews conducted in 2010-2011 including 11 nurses purposively selected from public hospitals and community centres in Jaén and Córdoba (Spain). A content analysis was performed, using Miles and Huberman as a reference and comprising the following steps: data reduction, data presentation, and data conclusion/verification. Data saturation was reached in these categories (obstacles). The obstacles perceived by nurses to introduce an evidence-based clinical practice (EBCP) were grouped into 3 major categories: obstacles related with professionals (routine-based practice, unwilling and stagnant attitudes, and lack of training in EBCP), obstacles related to the social context (reluctance from other professionals and from patients or families), and obstacles related to the organization (obsolete cultures that do not promote innovation in nursing care). This study highlights the persistence of various factors that hinder the use of research findings in clinical practice. The results underline the need to change the culture of healthcare organizations, to motivate professionals, and to break some of the resistance attitudes that hinder the implementation of evidence-based practice. Copyright © 2012 Elsevier España, S.L. All rights reserved.

  8. Have You Been Oriented? An Analysis of New Student Orientation and E-Orientation Programs at U.S. Community Colleges

    ERIC Educational Resources Information Center

    Chan, Matthew

    2017-01-01

    This study provides an overview and a snapshot of new student orientation (NSO) and new student e-orientation (NSEO) programs, with a focus on the content and feature analysis of the NSEOs. It offers an overview of currently available NSO programs of 100 randomly selected community colleges from a master list of nearly 900 community colleges in…

  9. Obstacle Avoidance On Roadways Using Range Data

    NASA Astrophysics Data System (ADS)

    Dunlay, R. Terry; Morgenthaler, David G.

    1987-02-01

    This report describes range data based obstacle avoidance techniques developed for use on an autonomous road-following robot vehicle. The purpose of these techniques is to detect and locate obstacles present in a road environment for navigation of a robot vehicle equipped with an active laser-based range sensor. Techniques are presented for obstacle detection, obstacle location, and coordinate transformations needed in the construction of Scene Models (symbolic structures representing the 3-D obstacle boundaries used by the vehicle's Navigator for path planning). These techniques have been successfully tested on an outdoor robotic vehicle, the Autonomous Land Vehicle (ALV), at speeds up to 3.5 km/hour.

  10. Electrophysiological correlates of retrieval orientation in reality monitoring.

    PubMed

    Rosburg, Timm; Mecklinger, Axel; Johansson, Mikael

    2011-02-14

    Retrieval orientation describes the modulation in the processing of retrieval cues by the nature of the targeted material in memory. Retrieval orientation is usually investigated by analyzing the cortical responses to new (unstudied) material when different memory contents are targeted. This approach avoids confounding effects of retrieval success. We investigated the neural correlates of retrieval orientation in reality monitoring with event-related potentials (ERPs) and assessed the impact of retrieval accuracy on obtained ERP measures. Thirty-two subjects studied visually presented object names that were followed either by a picture of that object (perceived condition) or by the instruction to mentally generate such a picture (imagine condition). Subsequently, subjects had to identify object names of one study condition and reject object names of the second study condition together with newly presented object names. The data analysis showed that object names were more accurately identified when they had been presented in the perceived condition. Two topographically distinct ERP effects of retrieval orientation were revealed: From 600 to 1100 ms after stimulus representation, ERPs were more positive at frontal electrode sites when object names from the imagine condition were targeted. The analysis of response-locked ERP data revealed an additional effect at posterior electrode sites, with more negative ERPs shortly after response onset when items from the imagine condition were targeted. The ERP effect at frontal electrode sites, but not at posterior electrode sites was modulated by relative memory accuracy, with stronger effects in subjects who had lower memory accuracy for items of the imagine condition. The findings are suggestive for a contribution of frontal brain areas to retrieval orientation processes in reality monitoring and indicate that neural correlates of retrieval orientation can be modulated by retrieval effort, with stronger activation of these

  11. Visual Search for Object Orientation Can Be Modulated by Canonical Orientation

    ERIC Educational Resources Information Center

    Ballaz, Cecile; Boutsen, Luc; Peyrin, Carole; Humphreys, Glyn W.; Marendaz, Christian

    2005-01-01

    The authors studied the influence of canonical orientation on visual search for object orientation. Displays consisted of pictures of animals whose axis of elongation was either vertical or tilted in their canonical orientation. Target orientation could be either congruent or incongruent with the object's canonical orientation. In Experiment 1,…

  12. Impact of Competency-Based and Target-Oriented Training on Employee Performance: A Case Study

    ERIC Educational Resources Information Center

    Arslan, Ridvan; Uzaslan, N. Tufan

    2017-01-01

    Some firms have applied different in-house training models to keep up with new technological innovations in their specific fields. This study investigated how a target-oriented in-house training programme should be developed and how it should be evaluated for effectiveness. The aim of the study was to develop, implement and evaluate a…

  13. Surface obstacles in pulsatile flow

    NASA Astrophysics Data System (ADS)

    Carr, Ian A.; Plesniak, Michael W.

    2017-11-01

    Flows past obstacles mounted on flat surfaces have been widely studied due to their ubiquity in nature and engineering. For nearly all of these studies, the freestream flow over the obstacle was steady, i.e., constant velocity, unidirectional flow. Unsteady, pulsatile flows occur frequently in biology, geophysics, biomedical engineering, etc. Our study is aimed at extending the comprehensive knowledge base that exists for steady flows to considerably more complex pulsatile flows. Characterizing the vortex and wake dynamics of flows around surface obstacles embedded in pulsatile flows can provide insights into the underlying physics in all wake and junction flows. In this study, we experimentally investigate the wake of two canonical obstacles: a cube and a circular cylinder with an aspect ratio of unity. Our previous studies of a surface-mounted hemisphere in pulsatile flow are used as a baseline for these two new, more complex geometries. Phase-averaged PIV and hot-wire anemometry are used to characterize the dynamics of coherent structures in the wake and at the windward junction of the obstacles. Complex physics occur during the deceleration phase of the pulsatile inflow. We propose a framework for understanding these physics based on self-induced vortex propagation, similar to the phenomena exhibited by vortex rings.

  14. Aviation obstacle auto-extraction using remote sensing information

    NASA Astrophysics Data System (ADS)

    Zimmer, N.; Lugsch, W.; Ravenscroft, D.; Schiefele, J.

    2008-10-01

    An Obstacle, in the aviation context, may be any natural, man-made, fixed or movable object, permanent or temporary. Currently, the most common way to detect relevant aviation obstacles from an aircraft or helicopter for navigation purposes and collision avoidance is the use of merged infrared and synthetic information of obstacle data. Several algorithms have been established to utilize synthetic and infrared images to generate obstacle information. There might be a situation however where the system is error-prone and may not be able to consistently determine the current environment. This situation can be avoided when the system knows the true position of the obstacle. The quality characteristics of the obstacle data strongly depends on the quality of the source data such as maps and official publications. In some countries such as newly industrializing and developing countries, quality and quantity of obstacle information is not available. The aviation world has two specifications - RTCA DO-276A and ICAO ANNEX 15 Ch. 10 - which describe the requirements for aviation obstacles. It is essential to meet these requirements to be compliant with the specifications and to support systems based on these specifications, e.g. 3D obstacle warning systems where accurate coordinates based on WGS-84 is a necessity. Existing aerial and satellite or soon to exist high quality remote sensing data makes it feasible to think about automated aviation obstacle data origination. This paper will describe the feasibility to auto-extract aviation obstacles from remote sensing data considering limitations of image and extraction technologies. Quality parameters and possible resolution of auto-extracted obstacle data will be discussed and presented.

  15. Context Oriented Information Integration

    NASA Astrophysics Data System (ADS)

    Mohania, Mukesh; Bhide, Manish; Roy, Prasan; Chakaravarthy, Venkatesan T.; Gupta, Himanshu

    Faced with growing knowledge management needs, enterprises are increasingly realizing the importance of seamlessly integrating critical business information distributed across both structured and unstructured data sources. Academicians have focused on this problem but there still remain a lot of obstacles for its widespread use in practice. One of the key problems is the absence of schema in unstructured text. In this paper we present a new paradigm for integrating information which overcomes this problem - that of Context Oriented Information Integration. The goal is to integrate unstructured data with the structured data present in the enterprise and use the extracted information to generate actionable insights for the enterprise. We present two techniques which enable context oriented information integration and show how they can be used for solving real world problems.

  16. Obstacles for Teachers to Integrate Technology with Instruction

    ERIC Educational Resources Information Center

    Alenezi, Abdullah

    2017-01-01

    This paper covers type one and two educational obstacles in using technology in the classrooms, and considering those obstacles tries to find the answer to the following overarching research question which can help to gauge some obstacles for the educational technology integration for elementary and high school education: What obstacles do…

  17. Fast obstacle detection based on multi-sensor information fusion

    NASA Astrophysics Data System (ADS)

    Lu, Linli; Ying, Jie

    2014-11-01

    Obstacle detection is one of the key problems in areas such as driving assistance and mobile robot navigation, which cannot meet the actual demand by using a single sensor. A method is proposed to realize the real-time access to the information of the obstacle in front of the robot and calculating the real size of the obstacle area according to the mechanism of the triangle similarity in process of imaging by fusing datum from a camera and an ultrasonic sensor, which supports the local path planning decision. In the part of image analyzing, the obstacle detection region is limited according to complementary principle. We chose ultrasonic detection range as the region for obstacle detection when the obstacle is relatively near the robot, and the travelling road area in front of the robot is the region for a relatively-long-distance detection. The obstacle detection algorithm is adapted from a powerful background subtraction algorithm ViBe: Visual Background Extractor. We extracted an obstacle free region in front of the robot in the initial frame, this region provided a reference sample set of gray scale value for obstacle detection. Experiments of detecting different obstacles at different distances respectively, give the accuracy of the obstacle detection and the error percentage between the calculated size and the actual size of the detected obstacle. Experimental results show that the detection scheme can effectively detect obstacles in front of the robot and provide size of the obstacle with relatively high dimensional accuracy.

  18. Tracked robot controllers for climbing obstacles autonomously

    NASA Astrophysics Data System (ADS)

    Vincent, Isabelle

    2009-05-01

    Research in mobile robot navigation has demonstrated some success in navigating flat indoor environments while avoiding obstacles. However, the challenge of analyzing complex environments to climb obstacles autonomously has had very little success due to the complexity of the task. Unmanned ground vehicles currently exhibit simple autonomous behaviours compared to the human ability to move in the world. This paper presents the control algorithms designed for a tracked mobile robot to autonomously climb obstacles by varying its tracks configuration. Two control algorithms are proposed to solve the autonomous locomotion problem for climbing obstacles. First, a reactive controller evaluates the appropriate geometric configuration based on terrain and vehicle geometric considerations. Then, a reinforcement learning algorithm finds alternative solutions when the reactive controller gets stuck while climbing an obstacle. The methodology combines reactivity to learning. The controllers have been demonstrated in box and stair climbing simulations. The experiments illustrate the effectiveness of the proposed approach for crossing obstacles.

  19. Planning Process Obstacles and Opportunities.

    ERIC Educational Resources Information Center

    Doyle, Patricia C.

    1997-01-01

    Argues that obstacles exist in the Public Library Association (PLA) planning process that can be resolved by developing relationships between materials in the collection and PLA roles. Proposes changes to help reduce conflict in the PLA planning process and discusses process obstacles, relationships as the key providing better service, and…

  20. Surface obstacles in pulsatile flow

    NASA Astrophysics Data System (ADS)

    Carr, Ian A.; Plesniak, Michael W.

    2016-11-01

    Flows past obstacles mounted on flat surfaces have been widely studied due to their ubiquity in nature and engineering. For nearly all of these studies, the freestream flow over the obstacle was steady, i.e. constant velocity unidirectional flow. Unsteady, pulsatile flows occur frequently in biology, geophysics, biomedical engineering, etc. Our study is aimed at extending the comprehensive knowledge base that exists for steady flows to considerably more complex pulsatile flows. Beyond the important practical applications, characterizing the vortex and wake dynamics of flows around surface obstacles embedded in pulsatile flows can provide insights into the underlying physics in all wake and junction flows. In this study, we experimentally investigated the wake of four canonical surface obstacles: hemisphere, cube, and circular cylinders with aspect ratio of 1:1 and 2:1. Phase-averaged PIV and hot-wire anemometry are used to characterize the dynamics of coherent structures in the wake and at the windward junction of the obstacles. Complex physics occur during the deceleration phase of the pulsatile inflow. We propose a framework for understanding these physics based on self-induced vortex propagation, similar to the phenomena exhibited by vortex rings. This material is based in part upon work supported by the National Science Foundation under Grant Number CBET-1236351, and GW Centeor Biomimetics and Bioinspired Engineering (COBRE).

  1. Orientation perception in rhesus monkeys (Macaca mulatta).

    PubMed

    Wakita, Masumi

    2008-07-01

    It was previously demonstrated that monkeys divide the orientation continuum into cardinal and oblique categories. However, it is still unclear how monkeys perceive within-category orientations. To better understand monkeys' perception of orientation, two experiments were conducted using five monkeys. In experiment 1, they were trained to identify either one cardinal or one oblique target orientation out of six orientations. The results showed that they readily identified the cardinal target whether it was oriented horizontally or vertically. However, a longer training period was needed to identify the oblique target orientation regardless of its degree and direction of tilt. In experiment 2, the same monkeys were trained to identify two-oblique target orientations out of six orientations. These orientations were paired, either sharing the degree of tilt, direction of tilt, or neither property. The results showed that the monkeys readily identified oblique orientations when they had either the same degree or direction of tilt. However, when the target orientations had neither the same degree nor direction of tilt, the animals had difficulty in identifying them. In summary, horizontal and vertical orientations are individually processed, indicating that monkeys do not have a category for cardinal orientation, but they may recognize cardinal orientations as non-obliques. In addition, monkeys efficiently abstract either the degree or the direction of tilt from oblique orientations, but they have difficulty combining these features to identify an oblique orientation. Thus, not all orientations within the oblique category are equally perceived.

  2. Inertial navigation sensor integrated obstacle detection system

    NASA Technical Reports Server (NTRS)

    Bhanu, Bir (Inventor); Roberts, Barry A. (Inventor)

    1992-01-01

    A system that incorporates inertial sensor information into optical flow computations to detect obstacles and to provide alternative navigational paths free from obstacles. The system is a maximally passive obstacle detection system that makes selective use of an active sensor. The active detection typically utilizes a laser. Passive sensor suite includes binocular stereo, motion stereo and variable fields-of-view. Optical flow computations involve extraction, derotation and matching of interest points from sequential frames of imagery, for range interpolation of the sensed scene, which in turn provides obstacle information for purposes of safe navigation.

  3. Dynamic clearance measure to evaluate locomotor and perceptuo-motor strategies used for obstacle circumvention in a virtual environment.

    PubMed

    Darekar, Anuja; Lamontagne, Anouk; Fung, Joyce

    2015-04-01

    Circumvention around an obstacle entails a dynamic interaction with the obstacle to maintain a safe clearance. We used a novel mathematical interpolation method based on the modified Shepard's method of Inverse Distance Weighting to compute dynamic clearance that reflected this interaction as well as minimal clearance. This proof-of-principle study included seven young healthy, four post-stroke and four healthy age-matched individuals. A virtual environment designed to assess obstacle circumvention was used to administer a locomotor (walking) and a perceptuo-motor (navigation with a joystick) task. In both tasks, participants were asked to navigate towards a target while avoiding collision with a moving obstacle that approached from either head-on, or 30° left or right. Among young individuals, dynamic clearance did not differ significantly between obstacle approach directions in both tasks. Post-stroke individuals maintained larger and smaller dynamic clearance during the locomotor and the perceptuo-motor task respectively as compared to age-matched controls. Dynamic clearance was larger than minimal distance from the obstacle irrespective of the group, task and obstacle approach direction. Also, in contrast to minimal distance, dynamic clearance can respond differently to different avoidance behaviors. Such a measure can be beneficial in contrasting obstacle avoidance behaviors in different populations with mobility problems. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Obstacles and problems of ethical leadership from the perspective of nursing leaders: a qualitative content analysis.

    PubMed

    Barkhordari-Sharifabad, Maasoumeh; Ashktorab, Tahereh; Atashzadeh-Shoorideh, Foroozan

    2017-01-01

    In the nursing profession, leadership plays a significant role in creating motivation and thus enabling nurses to provide high quality care. Ethics is an essential component of leadership qualifications and the ethical leader can help create an ethical atmosphere, offer ethical guidance, and ensure the occupational satisfaction of personnel through prioritizing moralities. However, some issues prevent the implementation of this type of leadership by nursing leaders. The aim of this study was to identify and describe some problems and obstacles in ethical leadership faced by nursing leaders, and to help them achieve more accurate information and broader perspective in this field. The present study was conducted using a qualitative approach and content analysis. A total of 14 nursing managers and educators were selected purposefully, and deep and semi-structured interviews were conducted with them. Content analysis was performed using an inductive approach. Three main categories were obtained after data analysis: ethical, cultural and managerial problems. "Ethical problems" pertain to doubt in ethical actions, ethical conflicts and ethical distress; "cultural problems" include organizational and social culture; and "managerial problems" are connected to organizational and staff-related issues. Nursing leaders put forth various aspects of the problems associated with ethical leadership in the clinical setting. This style of leadership could be promoted by developing suitable programs and providing clear-cut strategies for removing the current obstacles and correcting the organizational structure. This can lead to ethical improvement in nursing leaders and subsequently the nurses.

  5. Obstacles and problems of ethical leadership from the perspective of nursing leaders: a qualitative content analysis

    PubMed Central

    Barkhordari-Sharifabad, Maasoumeh; Ashktorab, Tahereh; Atashzadeh-Shoorideh, Foroozan

    2017-01-01

    In the nursing profession, leadership plays a significant role in creating motivation and thus enabling nurses to provide high quality care. Ethics is an essential component of leadership qualifications and the ethical leader can help create an ethical atmosphere, offer ethical guidance, and ensure the occupational satisfaction of personnel through prioritizing moralities. However, some issues prevent the implementation of this type of leadership by nursing leaders. The aim of this study was to identify and describe some problems and obstacles in ethical leadership faced by nursing leaders, and to help them achieve more accurate information and broader perspective in this field. The present study was conducted using a qualitative approach and content analysis. A total of 14 nursing managers and educators were selected purposefully, and deep and semi-structured interviews were conducted with them. Content analysis was performed using an inductive approach. Three main categories were obtained after data analysis: ethical, cultural and managerial problems. “Ethical problems” pertain to doubt in ethical actions, ethical conflicts and ethical distress; “cultural problems” include organizational and social culture; and “managerial problems” are connected to organizational and staff-related issues. Nursing leaders put forth various aspects of the problems associated with ethical leadership in the clinical setting. This style of leadership could be promoted by developing suitable programs and providing clear-cut strategies for removing the current obstacles and correcting the organizational structure. This can lead to ethical improvement in nursing leaders and subsequently the nurses. PMID:28523116

  6. Optimal partial mass transportation and obstacle Monge-Kantorovich equation

    NASA Astrophysics Data System (ADS)

    Igbida, Noureddine; Nguyen, Van Thanh

    2018-05-01

    Optimal partial mass transport, which is a variant of the optimal transport problem, consists in transporting effectively a prescribed amount of mass from a source to a target. The problem was first studied by Caffarelli and McCann (2010) [6] and Figalli (2010) [12] with a particular attention to the quadratic cost. Our aim here is to study the optimal partial mass transport problem with Finsler distance costs including the Monge cost given by the Euclidian distance. Our approach is different and our results do not follow from previous works. Among our results, we introduce a PDE of Monge-Kantorovich type with a double obstacle to characterize active submeasures, Kantorovich potential and optimal flow for the optimal partial transport problem. This new PDE enables us to study the uniqueness and monotonicity results for the active submeasures. Another interesting issue of our approach is its convenience for numerical analysis and computations that we develop in a separate paper [14] (Igbida and Nguyen, 2018).

  7. Shock interaction behind a pair of cylindrical obstacles

    NASA Astrophysics Data System (ADS)

    Liu, Heng; Mazumdar, Raoul; Eliasson, Veronica

    2014-11-01

    The body of work focuses on two-dimensional numerical simulations of shock interaction with a pair of cylindrical obstacles, varying the obstacle separation and incident shock strength. With the shock waves propagating parallel to the center-line between the two cylindrical obstacles, the shock strengths simulated vary from a Mach of 1.4 to a Mach of 2.4, against a wide range of obstacle separation distance to their diameters. These cases are simulated via a software package called Overture, which is used to solve the inviscid Euler equations of gas dynamics on overlapping grids with adaptive mesh refinement. The goal of these cases is to find a so-called ``safe'' region for obstacle spacing and varying shock Mach numbers, such that the pressure in the ``safe'' region is reduced downstream of the obstacles. The benefits apply to both building and armor design for the purpose of shock wave mitigation to keep humans and equipment safe. The results obtained from the simulations confirm that the length of the ``safe'' region and the degree of shock wave attenuation depend on the ratio of obstacle separation distance to obstacle diameter. The influence of various Mach number is also discussed.

  8. Impact of Oriented Clay Particles on X-Ray Spectroscopy Analysis

    NASA Astrophysics Data System (ADS)

    Lim, A. J. M. S.; Syazwani, R. N.; Wijeyesekera, D. C.

    2016-07-01

    Understanding the engineering properties of the mineralogy and microfabic of clayey soils is very complex and thus very difficult for soil characterization. Micromechanics of soils recognize that the micro structure and mineralogy of clay have a significant influence on its engineering behaviour. To achieve a more reliable quantitative evaluation of clay mineralogy, a proper sample preparation technique for quantitative clay mineral analysis is necessary. This paper presents the quantitative evaluation of elemental analysis and chemical characterization of oriented and random oriented clay particles using X-ray spectroscopy. Three different types of clays namely marine clay, bentonite and kaolin clay were studied. The oriented samples were prepared by placing the dispersed clay in water and left to settle on porous ceramic tiles by applying a relatively weak suction through a vacuum pump. Images form a Scanning Electron Microscope (SEM) was also used to show the comparison between the orientation patterns of both the sample preparation techniques. From the quantitative analysis of the X-ray spectroscopy, oriented sampling method showed more accuracy in identifying mineral deposits, because it produced better peak intensity on the spectrum and more mineral content can be identified compared to randomly oriented samples.

  9. Does physical exercise improve obstacle negotiation in the elderly? A systematic review.

    PubMed

    Guadagnin, Eliane C; da Rocha, Emmanuel S; Duysens, Jacques; Carpes, Felipe P

    2016-01-01

    Physical exercise improves walking in the elderly but much less is known about its effect on more challenged gait, such as obstacle negotiation. We conducted a systematic review to discuss the effects of regular physical exercise on kinematics and kinetics of obstacle negotiation in the elderly. A comprehensive literature search revealed 859 citations for review, whereof 206 studies entered the full-text analysis. After application of inclusion and exclusion criteria, 13 studies were included in this systematic review. Most of them presented a reasonable quality (average 0.68) but none of them reached the level of a randomized control trial. Interventions were heterogeneous, with training periods lasting from 5 days to 10 months. Studies assessed obstacle negotiation basically considering 3 types of testing paradigm, namely a walkway with either a single obstacle crossing, or with multiple obstacles, or else a treadmill with an obstacle avoidance task under time pressure. In general, longer training programs had better results and very short ones were not effective. A weekly frequency of 2-3 times was the most common among the studies showing positive effects. Regardless of exercises types performed, most of them were effective and so far, there is no consensus about the best exercise for improving obstacle negotiation. A lack of studies on this topic still is evident. Including a record of fall score can further help in deciding which programs are to be preferred. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  10. Detecting Negative Obstacles by Use of Radar

    NASA Technical Reports Server (NTRS)

    Mittskus, Anthony; Lux, James

    2006-01-01

    Robotic land vehicles would be equipped with small radar systems to detect negative obstacles, according to a proposal. The term "negative obstacles" denotes holes, ditches, and any other terrain features characterized by abrupt steep downslopes that could be hazardous for vehicles. Video cameras and other optically based obstacle-avoidance sensors now installed on some robotic vehicles cannot detect obstacles under adverse lighting conditions. Even under favorable lighting conditions, they cannot detect negative obstacles. A radar system according to the proposal would be of the frequency-modulation/ continuous-wave (FM/CW) type. It would be installed on a vehicle, facing forward, possibly with a downward slant of the main lobe(s) of the radar beam(s) (see figure). It would utilize one or more wavelength(s) of the order of centimeters. Because such wavelengths are comparable to the characteristic dimensions of terrain features associated with negative hazards, a significant amount of diffraction would occur at such features. In effect, the diffraction would afford a limited ability to see corners and to see around corners. Hence, the system might utilize diffraction to detect corners associated with negative obstacles. At the time of reporting the information for this article, preliminary analyses of diffraction at simple negative obstacles had been performed, but an explicit description of how the system would utilize diffraction was not available.

  11. Orientation tuning of contrast masking caused by motion streaks.

    PubMed

    Apthorp, Deborah; Cass, John; Alais, David

    2010-08-01

    We investigated whether the oriented trails of blur left by fast-moving dots (i.e., "motion streaks") effectively mask grating targets. Using a classic overlay masking paradigm, we varied mask contrast and target orientation to reveal underlying tuning. Fast-moving Gaussian blob arrays elevated thresholds for detection of static gratings, both monoptically and dichoptically. Monoptic masking at high mask (i.e., streak) contrasts is tuned for orientation and exhibits a similar bandwidth to masking functions obtained with grating stimuli (∼30 degrees). Dichoptic masking fails to show reliable orientation-tuned masking, but dichoptic masks at very low contrast produce a narrowly tuned facilitation (∼17 degrees). For iso-oriented streak masks and grating targets, we also explored masking as a function of mask contrast. Interestingly, dichoptic masking shows a classic "dipper"-like TVC function, whereas monoptic masking shows no dip and a steeper "handle". There is a very strong unoriented component to the masking, which we attribute to transiently biased temporal frequency masking. Fourier analysis of "motion streak" images shows interesting differences between dichoptic and monoptic functions and the information in the stimulus. Our data add weight to the growing body of evidence that the oriented blur of motion streaks contributes to the processing of fast motion signals.

  12. Obstacles and Affordances for Integer Reasoning: An Analysis of Children's Thinking and the History of Mathematics

    ERIC Educational Resources Information Center

    Bishop, Jessica Pierson; Lamb, Lisa L.; Philipp, Randolph A.; Whitacre, Ian; Schappelle, Bonnie P.; Lewis, Melinda L.

    2014-01-01

    We identify and document 3 cognitive obstacles, 3 cognitive affordances, and 1 type of integer understanding that can function as either an obstacle or affordance for learners while they extend their numeric domains from whole numbers to include negative integers. In particular, we highlight 2 key subsets of integer reasoning: understanding or…

  13. Obstacle Avoidance for Quadcopter using Ultrasonic Sensor

    NASA Astrophysics Data System (ADS)

    Fazlur Rahman, Muhammad; Adhy Sasongko, Rianto

    2018-04-01

    An obstacle avoidance system is being proposed. The system will combine available flight controller with a proposed avoidance method as a proof of concept. Quadcopter as a UAV is integrated with the system which consist of several modes in order to do avoidance. As the previous study, obstacle will be determined using ultrasonic sensor and servo. As result, the quadcopter will move according to its mode and successfully avoid obstacle.

  14. Role of curvatures in determining the characteristics of a string vibrating against a doubly curved obstacle

    NASA Astrophysics Data System (ADS)

    Singh, Harkirat; Wahi, Pankaj

    2017-08-01

    The motion of a string in the presence of a doubly curved obstacle is investigated. A mathematical model has been developed for a general shape of the obstacle. However, detailed analysis has been performed for a shape relevant to the Indian stringed musical instruments like Tanpura and Sitar. In particular, we explore the effect of obstacle's curvature in the plane perpendicular to the string axis on its motion. This geometrical feature of the obstacle introduces a coupling between motions in mutually perpendicular directions over and above the coupling due to the stretching nonlinearity. We find that only one planar motion is possible for our system. Small amplitude planar motions are stable to perturbations in the perpendicular direction resulting in non-whirling motions while large amplitude oscillations lead to whirling motions. The critical amplitude of oscillations, across which there is a transition in the qualitative behavior of the non-planar trajectories, is determined using Floquet theory. Our analysis reveals that a small obstacle curvature in a direction perpendicular to the string axis leads to a considerable reduction in the critical amplitudes required for initiation of whirling motions. Hence, this obstacle curvature has a destabilizing effect on the planar motions in contrast to the curvature along the string axis which stabilizes planar motions.

  15. AE Source Orientation by Plate Wave Analysis

    NASA Technical Reports Server (NTRS)

    Gorman, Michael R.; Prosser, William H.

    1991-01-01

    Lead breaks (Hsu-Neilsen source) were used to generate simulated acoustic emission signals in an aluminum plate at angles of 0, 30, 60, and 90 degrees with respect to the plane of the plate. This was accomplished by breaking the lead on slots cut into the plate at the respective angles. The out-of-plane and in-plane displacement components of the resulting signals were detected by broad band transducers and digitized. Analysis of the waveforms showed them to consist of the extensional and flexural plate modes. The amplitude of both components of the two modes was dependent on the source orientation angle. This suggests that plate wave analysis may be used to determine the source orientation of acoustic emission sources.

  16. Cross-orientation interactions in human vision.

    PubMed

    Roeber, Urte; Wong, Elaine M Y; Freeman, Alan W

    2008-03-18

    Humans can discriminate one visual contour from another on the basis of small differences in orientation. This capability depends on cortical detectors that are selective for a small range of orientations. We have measured this orientation bandwidth and the suppression that helps to shape it, with a reverse correlation technique. Human subjects were presented with a stream of randomly oriented gratings at a rate of 30 per second. Their task was to press a key whenever they saw an orientation nominated as the target. We analyzed the data by finding the probability density of two orientations: One preceded the key-press by the reaction time, and the second preceded the first by up to 100 ms. The results were as follows: (1) One grating facilitated the following one in producing a key-press when the gratings differed little in orientation. The estimate of orientation bandwidth resulting from this facilitation was 38 degrees . (2) A large angle between the two orientations reduced the probability of a key-press. This finding was best modelled as a suppression that did not vary with orientation, consistent with the idea that cross-orientation suppression is non-oriented. (3) Analysis of non-consecutive grating pairs showed that cross-orientation interactions lasted no longer than 67 ms.

  17. Stepping over obstacles: gait patterns of healthy young and old adults.

    PubMed

    Chen, H C; Ashton-Miller, J A; Alexander, N B; Schultz, A B

    1991-11-01

    Falls associated with tripping over an obstacle can be devastating to elderly individuals, yet little is known about the strategies used for stepping over obstacles by either old or young adults. The gait of gender-matched groups of 24 young and 24 old healthy adults (mean ages 22 and 71 years) was studied during a 4 m approach to and while stepping over obstacles of 0, 25, 51, or 152 mm height and in level obstacle-free walking. Optoelectronic cameras and recorders were used to record approach and obstacle crossing speeds as well as bilateral lower extremity kinematic parameters that described foot placement and movement trajectories relative to the obstacle. The results showed that age had no effect on minimum swing foot clearance (FC) over an obstacle. For the 25 mm obstacle, mean FC was 64 mm, or approximately three times that used in level gait; FC increased nonlinearly with obstacle height for all subjects. Although no age differences were found in obstacle-free gait, old adults exhibited a significantly more conservative strategy when crossing obstacles, with slower crossing speed, shorter step length, and shorter obstacle-heel strike distance. In addition, the old adults crossed the obstacle so that it was 10% further forward in their obstacle-crossing step. Although all subjects successfully avoided the riskiest form of obstacle contact, tripping, 4/24 healthy old adults stepped on an obstacle, demonstrating an increased risk for obstacle contact with age.

  18. Different protocols for analyzing behavior and adaptability in obstacle crossing in Parkinson's disease.

    PubMed

    Mollaei, Nafiseh; Bicho, Estela; Sousa, Nuno; Gago, Miguel Fernandes

    2017-01-01

    Imbalance and tripping over obstacles as a result of altered gait in older adults, especially in patients with Parkinson's disease (PD), are one of the most common causes of falls. During obstacle crossing, patients with PD modify their behavior in order to decrease the mechanical demands and enhance dynamic stability. Various descriptions of dynamic traits of gait that have been collected over longer periods, probably better synthesize the underlying structure and pattern of fluctuations in gait and can be more sensitive markers of aging or early neurological dysfunction and increased risk of falls. This confirmation challenges the clinimetric of different protocols and paradigms used for gait analysis up till now, in particular when analyzing obstacle crossing. The authors here present a critical review of current knowledge concerning the interplay between the cognition and gait in aging and PD, emphasizing the differences in gait behavior and adaptability while walking over different and challenging obstacle paradigms, and the implications of obstacle negotiation as a predictor of falls. Some evidence concerning the effectiveness of future rehabilitation protocols on reviving obstacle crossing behavior by trial and error relearning, taking advantage of dual-task paradigms, physical exercise, and virtual reality have been put forward in this article.

  19. Vision-Based UAV Flight Control and Obstacle Avoidance

    DTIC Science & Technology

    2006-01-01

    denoted it by Vb = (Vb1, Vb2 , Vb3). Fig. 2 shows the block diagram of the proposed vision-based motion analysis and obstacle avoidance system. We denote...structure analysis often involve computation- intensive computer vision tasks, such as feature extraction and geometric modeling. Computation-intensive...First, we extract a set of features from each block. 2) Second, we compute the distance between these two sets of features. In conventional motion

  20. Improving the Quality of Learning: A Framework for Target-Oriented Curriculum Renewal in Hong Kong. Revised.

    ERIC Educational Resources Information Center

    Clark, John L.; And Others

    This document sets out a "Framework" to underpin the development and ongoing renewal of the school curriculum in Hong Kong. It also indicates the bases on which the Framework is developed. The Framework forms the foundation of Hong Kong's Target-Oriented Curriculum (TOC) initiative and provides a useful reference for curriculum…

  1. Optimal consensus algorithm integrated with obstacle avoidance

    NASA Astrophysics Data System (ADS)

    Wang, Jianan; Xin, Ming

    2013-01-01

    This article proposes a new consensus algorithm for the networked single-integrator systems in an obstacle-laden environment. A novel optimal control approach is utilised to achieve not only multi-agent consensus but also obstacle avoidance capability with minimised control efforts. Three cost functional components are defined to fulfil the respective tasks. In particular, an innovative nonquadratic obstacle avoidance cost function is constructed from an inverse optimal control perspective. The other two components are designed to ensure consensus and constrain the control effort. The asymptotic stability and optimality are proven. In addition, the distributed and analytical optimal control law only requires local information based on the communication topology to guarantee the proposed behaviours, rather than all agents' information. The consensus and obstacle avoidance are validated through simulations.

  2. Zinc finger nuclease technology: advances and obstacles in modelling and treating genetic disorders.

    PubMed

    Jabalameli, Hamid Reza; Zahednasab, Hamid; Karimi-Moghaddam, Amin; Jabalameli, Mohammad Reza

    2015-03-01

    Zinc finger nucleases (ZFNs) are engineered restriction enzymes designed to target specific DNA sequences within the genome. Assembly of zinc finger DNA-binding domain to a DNA-cleavage domain enables the enzyme machinery to target unique locus in the genome and invoke endogenous DNA repair mechanisms. This machinery offers a versatile approach in allele editing and gene therapy. Here we discuss the architecture of ZFNs and strategies for generating targeted modifications within the genome. We review advances in gene therapy and modelling of the disease using these enzymes and finally, discuss the practical obstacles in using this technology. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Improvements in Obstacle Clearance Parameters and Reaction Time Over a Series of Obstacles Revealed After Five Repeated Testing Sessions in Older Adults.

    PubMed

    Jehu, Deborah A; Lajoie, Yves; Paquet, Nicole

    2017-12-21

    The purpose of this study was to investigate obstacle clearance and reaction time parameters when crossing a series of six obstacles in older adults. A second aim was to examine the repeated exposure of this testing protocol once per week for 5 weeks. In total, 10 older adults (five females; age: 67.0 ± 6.9 years) walked onto and over six obstacles of varying heights (range: 100-200 mm) while completing no reaction time, simple reaction time, and choice reaction time tasks once per week for 5 weeks. The highest obstacles elicited the lowest toe clearance, and the first three obstacles revealed smaller heel clearance compared with the last three obstacles. Dual tasking negatively impacted obstacle clearance parameters when information processing demands were high. Longer and less consistent time to completion was observed in Session 1 compared with Sessions 2-5. Finally, improvements in simple reaction time were displayed after Session 2, but choice reaction time gradually improved and did not reach a plateau after repeated testing.

  4. A stereo vision-based obstacle detection system in vehicles

    NASA Astrophysics Data System (ADS)

    Huh, Kunsoo; Park, Jaehak; Hwang, Junyeon; Hong, Daegun

    2008-02-01

    Obstacle detection is a crucial issue for driver assistance systems as well as for autonomous vehicle guidance function and it has to be performed with high reliability to avoid any potential collision with the front vehicle. The vision-based obstacle detection systems are regarded promising for this purpose because they require little infrastructure on a highway. However, the feasibility of these systems in passenger car requires accurate and robust sensing performance. In this paper, an obstacle detection system using stereo vision sensors is developed. This system utilizes feature matching, epipoplar constraint and feature aggregation in order to robustly detect the initial corresponding pairs. After the initial detection, the system executes the tracking algorithm for the obstacles. The proposed system can detect a front obstacle, a leading vehicle and a vehicle cutting into the lane. Then, the position parameters of the obstacles and leading vehicles can be obtained. The proposed obstacle detection system is implemented on a passenger car and its performance is verified experimentally.

  5. Statistics of dislocation pinning at localized obstacles

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

    Dutta, A.; Bhattacharya, M., E-mail: mishreyee@vecc.gov.in; Barat, P.

    2014-10-14

    Pinning of dislocations at nanosized obstacles like precipitates, voids, and bubbles is a crucial mechanism in the context of phenomena like hardening and creep. The interaction between such an obstacle and a dislocation is often studied at fundamental level by means of analytical tools, atomistic simulations, and finite element methods. Nevertheless, the information extracted from such studies cannot be utilized to its maximum extent on account of insufficient information about the underlying statistics of this process comprising a large number of dislocations and obstacles in a system. Here, we propose a new statistical approach, where the statistics of pinning ofmore » dislocations by idealized spherical obstacles is explored by taking into account the generalized size-distribution of the obstacles along with the dislocation density within a three-dimensional framework. Starting with a minimal set of material parameters, the framework employs the method of geometrical statistics with a few simple assumptions compatible with the real physical scenario. The application of this approach, in combination with the knowledge of fundamental dislocation-obstacle interactions, has successfully been demonstrated for dislocation pinning at nanovoids in neutron irradiated type 316-stainless steel in regard to the non-conservative motion of dislocations. An interesting phenomenon of transition from rare pinning to multiple pinning regimes with increasing irradiation temperature is revealed.« less

  6. Accessing Geospatial Services in Limited Bandwidth Service-Oriented Architecture (SOA) Environments

    ERIC Educational Resources Information Center

    Boggs, James D.

    2013-01-01

    First responders are continuously moving at an incident site and this movement requires them to access Service-Oriented Architecture services, such as a Web Map Service, via mobile wireless networks. First responders from inside a building often have problems in communicating to devices outside that building due to propagation obstacles. Dynamic…

  7. Search efficiency of biased migration towards stationary or moving targets in heterogeneously structured environments

    NASA Astrophysics Data System (ADS)

    Azimzade, Youness; Mashaghi, Alireza

    2017-12-01

    Efficient search acts as a strong selective force in biological systems ranging from cellular populations to predator-prey systems. The search processes commonly involve finding a stationary or mobile target within a heterogeneously structured environment where obstacles limit migration. An open generic question is whether random or directionally biased motions or a combination of both provide an optimal search efficiency and how that depends on the motility and density of targets and obstacles. To address this question, we develop a simple model that involves a random walker searching for its targets in a heterogeneous medium of bond percolation square lattice and used mean first passage time (〈T 〉 ) as an indication of average search time. Our analysis reveals a dual effect of directional bias on the minimum value of 〈T 〉 . For a homogeneous medium, directionality always decreases 〈T 〉 and a pure directional migration (a ballistic motion) serves as the optimized strategy, while for a heterogeneous environment, we find that the optimized strategy involves a combination of directed and random migrations. The relative contribution of these modes is determined by the density of obstacles and motility of targets. Existence of randomness and motility of targets add to the efficiency of search. Our study reveals generic and simple rules that govern search efficiency. Our findings might find application in a number of areas including immunology, cell biology, ecology, and robotics.

  8. Integrating Millimeter Wave Radar with a Monocular Vision Sensor for On-Road Obstacle Detection Applications

    PubMed Central

    Wang, Tao; Zheng, Nanning; Xin, Jingmin; Ma, Zheng

    2011-01-01

    This paper presents a systematic scheme for fusing millimeter wave (MMW) radar and a monocular vision sensor for on-road obstacle detection. As a whole, a three-level fusion strategy based on visual attention mechanism and driver’s visual consciousness is provided for MMW radar and monocular vision fusion so as to obtain better comprehensive performance. Then an experimental method for radar-vision point alignment for easy operation with no reflection intensity of radar and special tool requirements is put forward. Furthermore, a region searching approach for potential target detection is derived in order to decrease the image processing time. An adaptive thresholding algorithm based on a new understanding of shadows in the image is adopted for obstacle detection, and edge detection is used to assist in determining the boundary of obstacles. The proposed fusion approach is verified through real experimental examples of on-road vehicle/pedestrian detection. In the end, the experimental results show that the proposed method is simple and feasible. PMID:22164117

  9. Integrating millimeter wave radar with a monocular vision sensor for on-road obstacle detection applications.

    PubMed

    Wang, Tao; Zheng, Nanning; Xin, Jingmin; Ma, Zheng

    2011-01-01

    This paper presents a systematic scheme for fusing millimeter wave (MMW) radar and a monocular vision sensor for on-road obstacle detection. As a whole, a three-level fusion strategy based on visual attention mechanism and driver's visual consciousness is provided for MMW radar and monocular vision fusion so as to obtain better comprehensive performance. Then an experimental method for radar-vision point alignment for easy operation with no reflection intensity of radar and special tool requirements is put forward. Furthermore, a region searching approach for potential target detection is derived in order to decrease the image processing time. An adaptive thresholding algorithm based on a new understanding of shadows in the image is adopted for obstacle detection, and edge detection is used to assist in determining the boundary of obstacles. The proposed fusion approach is verified through real experimental examples of on-road vehicle/pedestrian detection. In the end, the experimental results show that the proposed method is simple and feasible.

  10. Selective enhancement of orientation tuning before saccades.

    PubMed

    Ohl, Sven; Kuper, Clara; Rolfs, Martin

    2017-11-01

    Saccadic eye movements cause a rapid sweep of the visual image across the retina and bring the saccade's target into high-acuity foveal vision. Even before saccade onset, visual processing is selectively prioritized at the saccade target. To determine how this presaccadic attention shift exerts its influence on visual selection, we compare the dynamics of perceptual tuning curves before movement onset at the saccade target and in the opposite hemifield. Participants monitored a 30-Hz sequence of randomly oriented gratings for a target orientation. Combining a reverse correlation technique previously used to study orientation tuning in neurons and general additive mixed modeling, we found that perceptual reports were tuned to the target orientation. The gain of orientation tuning increased markedly within the last 100 ms before saccade onset. In addition, we observed finer orientation tuning right before saccade onset. This increase in gain and tuning occurred at the saccade target location and was not observed at the incongruent location in the opposite hemifield. The present findings suggest, therefore, that presaccadic attention exerts its influence on vision in a spatially and feature-selective manner, enhancing performance and sharpening feature tuning at the future gaze location before the eyes start moving.

  11. Mathematical Models of Smart Obstacles

    DTIC Science & Technology

    2006-10-01

    Matematica “G. Castelnuovo” Università di Roma “La Sapienza”, Piazzale Aldo Moro 2 00185 Roma Italy Ph. N. +39-06-49913282, FAX N. +39-06...Dipartimento di Matematica G. Castelnuovo Università di Roma La Sapienza, Piazzale Aldo Moro 2 00185 Roma Italy 8. PERFORMING ORGANIZATION REPORT NUMBER 9... Matematica G. Castelnuovo Università di Roma “La Sapienza” 00185 Roma, Italy 2 Smart (or active) obstacles are obstacles that when illuminated by an

  12. Imaging objects behind small obstacles using axicon lens

    NASA Astrophysics Data System (ADS)

    Perinchery, Sandeep M.; Shinde, Anant; Murukeshan, V. M.

    2017-06-01

    Axicon lenses are conical prisms, which are known to focus a light source to a line comprising of multiple points along the optical axis. In this study, we analyze the potential of axicon lenses to view, image and record the object behind opaque obstacles in free space. The advantage of an axicon lens over a regular lens is demonstrated experimentally. Parameters such as obstacle size, object and the obstacle position in the context of imaging behind obstacles are tested using Zemax optical simulation. This proposed concept can be easily adapted to most of the optical imaging methods and microscopy modalities.

  13. Target-Oriented High-Resolution SAR Image Formation via Semantic Information Guided Regularizations

    NASA Astrophysics Data System (ADS)

    Hou, Biao; Wen, Zaidao; Jiao, Licheng; Wu, Qian

    2018-04-01

    Sparsity-regularized synthetic aperture radar (SAR) imaging framework has shown its remarkable performance to generate a feature enhanced high resolution image, in which a sparsity-inducing regularizer is involved by exploiting the sparsity priors of some visual features in the underlying image. However, since the simple prior of low level features are insufficient to describe different semantic contents in the image, this type of regularizer will be incapable of distinguishing between the target of interest and unconcerned background clutters. As a consequence, the features belonging to the target and clutters are simultaneously affected in the generated image without concerning their underlying semantic labels. To address this problem, we propose a novel semantic information guided framework for target oriented SAR image formation, which aims at enhancing the interested target scatters while suppressing the background clutters. Firstly, we develop a new semantics-specific regularizer for image formation by exploiting the statistical properties of different semantic categories in a target scene SAR image. In order to infer the semantic label for each pixel in an unsupervised way, we moreover induce a novel high-level prior-driven regularizer and some semantic causal rules from the prior knowledge. Finally, our regularized framework for image formation is further derived as a simple iteratively reweighted $\\ell_1$ minimization problem which can be conveniently solved by many off-the-shelf solvers. Experimental results demonstrate the effectiveness and superiority of our framework for SAR image formation in terms of target enhancement and clutters suppression, compared with the state of the arts. Additionally, the proposed framework opens a new direction of devoting some machine learning strategies to image formation, which can benefit the subsequent decision making tasks.

  14. Automated Dispersion and Orientation Analysis for Carbon Nanotube Reinforced Polymer Composites

    PubMed Central

    Gao, Yi; Li, Zhuo; Lin, Ziyin; Zhu, Liangjia; Tannenbaum, Allen; Bouix, Sylvain; Wong, C.P.

    2012-01-01

    The properties of carbon nanotube (CNT)/polymer composites are strongly dependent on the dispersion and orientation of CNTs in the host matrix. Quantification of the dispersion and orientation of CNTs by microstructure observation and image analysis has been demonstrated as a useful way to understand the structure-property relationship of CNT/polymer composites. However, due to the various morphologies and large amount of CNTs in one image, automatic and accurate identification of CNTs has become the bottleneck for dispersion/orientation analysis. To solve this problem, shape identification is performed for each pixel in the filler identification step, so that individual CNT can be exacted from images automatically. The improved filler identification enables more accurate analysis of CNT dispersion and orientation. The obtained dispersion index and orientation index of both synthetic and real images from model compounds correspond well with the observations. Moreover, these indices help to explain the electrical properties of CNT/Silicone composite, which is used as a model compound. This method can also be extended to other polymer composites with high aspect ratio fillers. PMID:23060008

  15. Assessing the ground vibrations produced by a heavy vehicle traversing a traffic obstacle.

    PubMed

    Ducarne, Loïc; Ainalis, Daniel; Kouroussis, Georges

    2018-01-15

    Despite advancements in alternative transport networks, road transport remains the dominant mode in many modern and developing countries. The ground-borne motions produced by the passage of a heavy vehicle over a geometric obstacle (e.g. speed hump, train tracks) pose a fundamental problem in transport annoyance in urban areas. In order to predict the ground vibrations generated by the passage of a heavy vehicle over a geometric obstacle, a two-step numerical model is developed. The first step involves simulating the dynamic loads generated by the heavy vehicle using a multibody approach, which includes the tyre-obstacle-ground interaction. The second step involves the simulation of the ground wave propagation using a three dimensional finite element model. The simulation is able to be decoupled due to the large difference in stiffness between the vehicle's tyres and the road. First, the two-step model is validated using an experimental case study available in the literature. A sensitivity analysis is then presented, examining the influence of various factors on the generated ground vibrations. Factors investigated include obstacle shape, obstacle dimensions, vehicle speed, and tyre stiffness. The developed model can be used as a tool in the early planning stages to predict the ground vibrations generated by the passage of a heavy vehicle over an obstacle in urban areas. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. A nonlinear model predictive control formulation for obstacle avoidance in high-speed autonomous ground vehicles in unstructured environments

    NASA Astrophysics Data System (ADS)

    Liu, Jiechao; Jayakumar, Paramsothy; Stein, Jeffrey L.; Ersal, Tulga

    2018-06-01

    This paper presents a nonlinear model predictive control (MPC) formulation for obstacle avoidance in high-speed, large-size autono-mous ground vehicles (AGVs) with high centre of gravity (CoG) that operate in unstructured environments, such as military vehicles. The term 'unstructured' in this context denotes that there are no lanes or traffic rules to follow. Existing MPC formulations for passenger vehicles in structured environments do not readily apply to this context. Thus, a new nonlinear MPC formulation is developed to navigate an AGV from its initial position to a target position at high-speed safely. First, a new cost function formulation is used that aims to find the shortest path to the target position, since no reference trajectory exists in unstructured environments. Second, a region partitioning approach is used in conjunction with a multi-phase optimal control formulation to accommodate the complicated forms the obstacle-free region can assume due to the presence of multiple obstacles in the prediction horizon in an unstructured environment. Third, the no-wheel-lift-off condition, which is the major dynamical safety concern for high-speed, high-CoG AGVs, is ensured by limiting the steering angle within a range obtained offline using a 14 degrees-of-freedom vehicle dynamics model. Thus, a safe, high-speed navigation is enabled in an unstructured environment. Simulations of an AGV approaching multiple obstacles are provided to demonstrate the effectiveness of the algorithm.

  17. Mesenchymal stem cell-mediated cancer therapy: A dual-targeted strategy of personalized medicine

    PubMed Central

    Sun, Xu-Yong; Nong, Jiang; Qin, Ke; Warnock, Garth L; Dai, Long-Jun

    2011-01-01

    Cancer remains one of the leading causes of mortality and morbidity throughout the world. To a significant extent, current conventional cancer therapies are symptomatic and passive in nature. The major obstacle to the development of effective cancer therapy is believed to be the absence of sufficient specificity. Since the discovery of the tumor-oriented homing capacity of mesenchymal stem cells (MSCs), the application of specific anticancer gene-engineered MSCs has held great potential for cancer therapies. The dual-targeted strategy is based on MSCs’ capacity of tumor-directed migration and incorporation and in situ expression of tumor-specific anticancer genes. With the aim of translating bench work into meaningful clinical applications, we describe the tumor tropism of MSCs and their use as therapeutic vehicles, the dual-targeted anticancer potential of engineered MSCs and a putative personalized strategy with anticancer gene-engineered MSCs. PMID:22180830

  18. Passive detection of subpixel obstacles for flight safety

    NASA Astrophysics Data System (ADS)

    Nixon, Matthew D.; Loveland, Rohan C.

    2001-12-01

    Military aircraft fly below 100 ft. above ground level in support of their missions. These aircraft include fixed and rotary wing and may be manned or unmanned. Flying at these low altitudes presents a safety hazard to the aircrew and aircraft, due to the occurrences of obstacles within the aircraft's flight path. The pilot must rely on eyesight and in some cases, infrared sensors to see obstacles. Many conditions can exacerbate visibility creating a situation in which obstacles are essentially invisible, creating a safety hazard, even to an alerted aircrew. Numerous catastrophic accidents have occurred in which aircraft have collided with undetected obstacles. Accidents of this type continue to be a problem for low flying military and commercial aircraft. Unmanned Aerial Vehicles (UAVs) have the same problem, whether operating autonomously or under control of a ground operator. Boeing-SVS has designed a passive, small, low- cost (under $100k) gimbaled, infrared imaging based system with advanced obstacle detection algorithms. Obstacles are detected in the infrared band, and linear features are analyzed by innovative cellular automata based software. These algorithms perform detection and location of sub-pixel linear features. The detection of the obstacles is performed on a frame by frame basis, in real time. Processed images are presented to the aircrew on their display as color enhanced features. The system has been designed such that the detected obstacles are displayed to the aircrew in sufficient time to react and maneuver the aircraft to safety. A patent for this system is on file with the US patent office, and all material herein should be treated accordingly.

  19. Masking reduces orientation selectivity in rat visual cortex

    PubMed Central

    Alwis, Dasuni S.; Richards, Katrina L.

    2016-01-01

    In visual masking the perception of a target stimulus is impaired by a preceding (forward) or succeeding (backward) mask stimulus. The illusion is of interest because it allows uncoupling of the physical stimulus, its neuronal representation, and its perception. To understand the neuronal correlates of masking, we examined how masks affected the neuronal responses to oriented target stimuli in the primary visual cortex (V1) of anesthetized rats (n = 37). Target stimuli were circular gratings with 12 orientations; mask stimuli were plaids created as a binarized sum of all possible target orientations. Spatially, masks were presented either overlapping or surrounding the target. Temporally, targets and masks were presented for 33 ms, but the stimulus onset asynchrony (SOA) of their relative appearance was varied. For the first time, we examine how spatially overlapping and center-surround masking affect orientation discriminability (rather than visibility) in V1. Regardless of the spatial or temporal arrangement of stimuli, the greatest reductions in firing rate and orientation selectivity occurred for the shortest SOAs. Interestingly, analyses conducted separately for transient and sustained target response components showed that changes in orientation selectivity do not always coincide with changes in firing rate. Given the near-instantaneous reductions observed in orientation selectivity even when target and mask do not spatially overlap, we suggest that monotonic visual masking is explained by a combination of neural integration and lateral inhibition. PMID:27535373

  20. Design principles for data- and change-oriented organisational analysis in workplace health promotion.

    PubMed

    Inauen, A; Jenny, G J; Bauer, G F

    2012-06-01

    This article focuses on organizational analysis in workplace health promotion (WHP) projects. It shows how this analysis can be designed such that it provides rational data relevant to the further context-specific and goal-oriented planning of WHP and equally supports individual and organizational change processes implied by WHP. Design principles for organizational analysis were developed on the basis of a narrative review of the guiding principles of WHP interventions and organizational change as well as the scientific principles of data collection. Further, the practical experience of WHP consultants who routinely conduct organizational analysis was considered. This resulted in a framework with data-oriented and change-oriented design principles, addressing the following elements of organizational analysis in WHP: planning the overall procedure, data content, data-collection methods and information processing. Overall, the data-oriented design principles aim to produce valid, reliable and representative data, whereas the change-oriented design principles aim to promote motivation, coherence and a capacity for self-analysis. We expect that the simultaneous consideration of data- and change-oriented design principles for organizational analysis will strongly support the WHP process. We finally illustrate the applicability of the design principles to health promotion within a WHP case study.

  1. Obstacle avoidance for redundant robots using configuration control

    NASA Technical Reports Server (NTRS)

    Seraji, Homayoun (Inventor); Colbaugh, Richard D. (Inventor); Glass, Kristin L. (Inventor)

    1992-01-01

    A redundant robot control scheme is provided for avoiding obstacles in a workspace during the motion of an end effector along a preselected trajectory by stopping motion of the critical point on the robot closest to the obstacle when the distance between is reduced to a predetermined sphere of influence surrounding the obstacle. Algorithms are provided for conveniently determining the critical point and critical distance.

  2. Different protocols for analyzing behavior and adaptability in obstacle crossing in Parkinson’s disease

    PubMed Central

    Mollaei, Nafiseh; Bicho, Estela; Sousa, Nuno; Gago, Miguel Fernandes

    2017-01-01

    Imbalance and tripping over obstacles as a result of altered gait in older adults, especially in patients with Parkinson’s disease (PD), are one of the most common causes of falls. During obstacle crossing, patients with PD modify their behavior in order to decrease the mechanical demands and enhance dynamic stability. Various descriptions of dynamic traits of gait that have been collected over longer periods, probably better synthesize the underlying structure and pattern of fluctuations in gait and can be more sensitive markers of aging or early neurological dysfunction and increased risk of falls. This confirmation challenges the clinimetric of different protocols and paradigms used for gait analysis up till now, in particular when analyzing obstacle crossing. The authors here present a critical review of current knowledge concerning the interplay between the cognition and gait in aging and PD, emphasizing the differences in gait behavior and adaptability while walking over different and challenging obstacle paradigms, and the implications of obstacle negotiation as a predictor of falls. Some evidence concerning the effectiveness of future rehabilitation protocols on reviving obstacle crossing behavior by trial and error relearning, taking advantage of dual-task paradigms, physical exercise, and virtual reality have been put forward in this article. PMID:29158667

  3. Obstacle avoidance locomotor tasks: adaptation, memory and skill transfer.

    PubMed

    Kloter, Evelyne; Dietz, Volker

    2012-05-01

    The aim of this study was to explore the neural basis of adaptation, memory and skill transfer during human stepping over obstacles. Whilst walking on a treadmill, subjects had to perform uni- and bilateral obstacle steps. Acoustic feedback information about foot clearance was provided. Non-noxious electrical stimuli were applied to the right tibial nerve during the mid-stance phase of the right leg, i.e. 'prior' to the right or 'during' the left leg swing over the obstacle. The electromyogram (EMG) responses evoked by these stimuli in arm and leg muscles are known to reflect the neural coordination during normal and obstacle steps. The leading and trailing legs rapidly adapted foot clearance during obstacle steps with small further changes when the same obstacle condition was repeated. This adaptation was associated with a corresponding decrease in arm and leg muscle reflex EMG responses. Arm (but not leg) muscle EMG responses were greater when the stimulus was applied 'during' obstacle crossing by the left leg leading compared with stimulation 'prior' to right leg swing over the obstacle. A corresponding difference existed in arm muscle background EMG. The results indicate that, firstly, the somatosensory information gained by the performance and adaptation of uni- and bilateral obstacle stepping becomes transferred to the trailing leg in a context-specific manner. Secondly, EMG activity in arm and leg muscles parallels biomechanical adaptation of foot clearance. Thirdly, a consistently high EMG activity in the arm muscles during swing over the obstacle is required for equilibrium control. Thus, such a precision locomotor task is achieved by a context-specific, coordinated activation of arm and leg muscles for performance and equilibrium control that includes adaptation, memory and skill transfer. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  4. Object-Oriented Multi-Disciplinary Design, Analysis, and Optimization Tool

    NASA Technical Reports Server (NTRS)

    Pak, Chan-gi

    2011-01-01

    An Object-Oriented Optimization (O3) tool was developed that leverages existing tools and practices, and allows the easy integration and adoption of new state-of-the-art software. At the heart of the O3 tool is the Central Executive Module (CEM), which can integrate disparate software packages in a cross platform network environment so as to quickly perform optimization and design tasks in a cohesive, streamlined manner. This object-oriented framework can integrate the analysis codes for multiple disciplines instead of relying on one code to perform the analysis for all disciplines. The CEM was written in FORTRAN and the script commands for each performance index were submitted through the use of the FORTRAN Call System command. In this CEM, the user chooses an optimization methodology, defines objective and constraint functions from performance indices, and provides starting and side constraints for continuous as well as discrete design variables. The structural analysis modules such as computations of the structural weight, stress, deflection, buckling, and flutter and divergence speeds have been developed and incorporated into the O3 tool to build an object-oriented Multidisciplinary Design, Analysis, and Optimization (MDAO) tool.

  5. Biologically-inspired adaptive obstacle negotiation behavior of hexapod robots

    PubMed Central

    Goldschmidt, Dennis; Wörgötter, Florentin; Manoonpong, Poramate

    2014-01-01

    Neurobiological studies have shown that insects are able to adapt leg movements and posture for obstacle negotiation in changing environments. Moreover, the distance to an obstacle where an insect begins to climb is found to be a major parameter for successful obstacle negotiation. Inspired by these findings, we present an adaptive neural control mechanism for obstacle negotiation behavior in hexapod robots. It combines locomotion control, backbone joint control, local leg reflexes, and neural learning. While the first three components generate locomotion including walking and climbing, the neural learning mechanism allows the robot to adapt its behavior for obstacle negotiation with respect to changing conditions, e.g., variable obstacle heights and different walking gaits. By successfully learning the association of an early, predictive signal (conditioned stimulus, CS) and a late, reflex signal (unconditioned stimulus, UCS), both provided by ultrasonic sensors at the front of the robot, the robot can autonomously find an appropriate distance from an obstacle to initiate climbing. The adaptive neural control was developed and tested first on a physical robot simulation, and was then successfully transferred to a real hexapod robot, called AMOS II. The results show that the robot can efficiently negotiate obstacles with a height up to 85% of the robot's leg length in simulation and 75% in a real environment. PMID:24523694

  6. Obstacle avoidance in social groups: new insights from asynchronous models

    PubMed Central

    Croft, Simon; Budgey, Richard; Pitchford, Jonathan W.; Wood, A. Jamie

    2015-01-01

    For moving animals, the successful avoidance of hazardous obstacles is an important capability. Despite this, few models of collective motion have addressed the relationship between behavioural and social features and obstacle avoidance. We develop an asynchronous individual-based model for social movement which allows social structure within groups to be included. We assess the dynamics of group navigation and resulting collision risk in the context of information transfer through the system. In agreement with previous work, we find that group size has a nonlinear effect on collision risk. We implement examples of possible network structures to explore the impact social preferences have on collision risk. We show that any social heterogeneity induces greater obstacle avoidance with further improvements corresponding to groups containing fewer influential individuals. The model provides a platform for both further theoretical investigation and practical application. In particular, we argue that the role of social structures within bird flocks may have an important role to play in assessing the risk of collisions with wind turbines, but that new methods of data analysis are needed to identify these social structures. PMID:25833245

  7. Surface immobilized antibody orientation determined using ToF-SIMS and multivariate analysis.

    PubMed

    Welch, Nicholas G; Madiona, Robert M T; Payten, Thomas B; Easton, Christopher D; Pontes-Braz, Luisa; Brack, Narelle; Scoble, Judith A; Muir, Benjamin W; Pigram, Paul J

    2017-06-01

    Antibody orientation at solid phase interfaces plays a critical role in the sensitive detection of biomolecules during immunoassays. Correctly oriented antibodies with solution-facing antigen binding regions have improved antigen capture as compared to their randomly oriented counterparts. Direct characterization of oriented proteins with surface analysis methods still remains a challenge however surface sensitive techniques such as Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) provide information-rich data that can be used to probe antibody orientation. Diethylene glycol dimethyl ether plasma polymers (DGpp) functionalized with chromium (DGpp+Cr) have improved immunoassay performance that is indicative of preferential antibody orientation. Herein, ToF-SIMS data from proteolytic fragments of anti-EGFR antibody bound to DGpp and DGpp+Cr are used to construct artificial neural network (ANN) and principal component analysis (PCA) models indicative of correctly oriented systems. Whole antibody samples (IgG) test against each of the models indicated preferential antibody orientation on DGpp+Cr. Cross-reference between ANN and PCA models yield 20 mass fragments associated with F(ab') 2 region representing correct orientation, and 23 mass fragments associated with the Fc region representing incorrect orientation. Mass fragments were then compared to amino acid fragments and amino acid composition in F(ab') 2 and Fc regions. A ratio of the sum of the ToF-SIMS ion intensities from the F(ab') 2 fragments to the Fc fragments demonstrated a 50% increase in intensity for IgG on DGpp+Cr as compared to DGpp. The systematic data analysis methodology employed herein offers a new approach for the investigation of antibody orientation applicable to a range of substrates. Controlled orientation of antibodies at solid phases is critical for maximizing antigen detection in biosensors and immunoassays. Surface-sensitive techniques (such as ToF-SIMS), capable of direct

  8. Endogenous orienting in the archer fish.

    PubMed

    Saban, William; Sekely, Liora; Klein, Raymond M; Gabay, Shai

    2017-07-18

    The literature has long emphasized the neocortex's role in volitional processes. In this work, we examined endogenous orienting in an evolutionarily older species, the archer fish, which lacks neocortex-like cells. We used Posner's classic endogenous cuing task, in which a centrally presented, spatially informative cue is followed by a target. The fish responded to the target by shooting a stream of water at it. Interestingly, the fish demonstrated a human-like "volitional" facilitation effect: their reaction times to targets that appeared on the side indicated by the precue were faster than their reaction times to targets on the opposite side. The fish also exhibited inhibition of return, an aftermath of orienting that commonly emerges only in reflexive orienting tasks in human participants. We believe that this pattern demonstrates the acquisition of an arbitrary connection between spatial orienting and a nonspatial feature of a centrally presented stimulus in nonprimate species. In the literature on human attention, orienting in response to such contingencies has been strongly associated with volitional control. We discuss the implications of these results for the evolution of orienting, and for the study of volitional processes in all species, including humans.

  9. Endogenous orienting in the archer fish

    PubMed Central

    Sekely, Liora; Klein, Raymond M.; Gabay, Shai

    2017-01-01

    The literature has long emphasized the neocortex’s role in volitional processes. In this work, we examined endogenous orienting in an evolutionarily older species, the archer fish, which lacks neocortex-like cells. We used Posner’s classic endogenous cuing task, in which a centrally presented, spatially informative cue is followed by a target. The fish responded to the target by shooting a stream of water at it. Interestingly, the fish demonstrated a human-like “volitional” facilitation effect: their reaction times to targets that appeared on the side indicated by the precue were faster than their reaction times to targets on the opposite side. The fish also exhibited inhibition of return, an aftermath of orienting that commonly emerges only in reflexive orienting tasks in human participants. We believe that this pattern demonstrates the acquisition of an arbitrary connection between spatial orienting and a nonspatial feature of a centrally presented stimulus in nonprimate species. In the literature on human attention, orienting in response to such contingencies has been strongly associated with volitional control. We discuss the implications of these results for the evolution of orienting, and for the study of volitional processes in all species, including humans. PMID:28673997

  10. Enhanced cellulose orientation analysis in complex model plant tissues.

    PubMed

    Rüggeberg, Markus; Saxe, Friederike; Metzger, Till H; Sundberg, Björn; Fratzl, Peter; Burgert, Ingo

    2013-09-01

    The orientation distribution of cellulose microfibrils in the plant cell wall is a key parameter for understanding anisotropic plant growth and mechanical behavior. However, precisely visualizing cellulose orientation in the plant cell wall has ever been a challenge due to the small size of the cellulose microfibrils and the complex network of polymers in the plant cell wall. X-ray diffraction is one of the most frequently used methods for analyzing cellulose orientation in single cells and plant tissues, but the interpretation of the diffraction images is complex. Traditionally, circular or square cells and Gaussian orientation of the cellulose microfibrils have been assumed to elucidate cellulose orientation from the diffraction images. However, the complex tissue structures of common model plant systems such as Arabidopsis or aspen (Populus) require a more sophisticated approach. We present an evaluation procedure which takes into account the precise cell geometry and is able to deal with complex microfibril orientation distributions. The evaluation procedure reveals the entire orientation distribution of the cellulose microfibrils, reflecting different orientations within the multi-layered cell wall. By analyzing aspen wood and Arabidopsis stems we demonstrate the versatility of this method and show that simplifying assumptions on geometry and orientation distributions can lead to errors in the calculated microfibril orientation pattern. The simulation routine is intended to be used as a valuable tool for nanostructural analysis of plant cell walls and is freely available from the authors on request. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Obstacle Detection Algorithms for Aircraft Navigation: Performance Characterization of Obstacle Detection Algorithms for Aircraft Navigation

    NASA Technical Reports Server (NTRS)

    Kasturi, Rangachar; Camps, Octavia; Coraor, Lee

    2000-01-01

    The research reported here is a part of NASA's Synthetic Vision System (SVS) project for the development of a High Speed Civil Transport Aircraft (HSCT). One of the components of the SVS is a module for detection of potential obstacles in the aircraft's flight path by analyzing the images captured by an on-board camera in real-time. Design of such a module includes the selection and characterization of robust, reliable, and fast techniques and their implementation for execution in real-time. This report describes the results of our research in realizing such a design. It is organized into three parts. Part I. Data modeling and camera characterization; Part II. Algorithms for detecting airborne obstacles; and Part III. Real time implementation of obstacle detection algorithms on the Datacube MaxPCI architecture. A list of publications resulting from this grant as well as a list of relevant publications resulting from prior NASA grants on this topic are presented.

  12. Virtual Reality-Based Training to Improve Obstacle-Crossing Performance and Dynamic Balance in Patients With Parkinson's Disease.

    PubMed

    Liao, Ying-Yi; Yang, Yea-Ru; Cheng, Shih-Jung; Wu, Yih-Ru; Fuh, Jong-Ling; Wang, Ray-Yau

    2015-08-01

    Obstacle crossing is a balance-challenging task and can cause falls in people with Parkinson's disease (PD). However, programs for people with PD that effectively target obstacle crossing and dynamic balance have not been established. To examine the effects of virtual reality-based exercise on obstacle crossing performance and dynamic balance in participants with PD. Thirty-six participants with a diagnosis of PD (Hoehn and Yahr score ranging 1 to 3) were randomly assigned to one of three groups. In the exercise groups, participants received virtual reality-based Wii Fit exercise (VRWii group) or traditional exercise (TE group) for 45 minutes, followed by 15 minutes of treadmill training in each session for a total of 12 sessions over 6 weeks. Participants in the control group received no structured exercise program. Primary outcomes included obstacle crossing performance (crossing velocity, stride length, and vertical toe obstacle clearance) and dynamic balance (maximal excursion, movement velocity, and directional control measured by the limits-of-stability test). Secondary outcomes included sensory organization test (SOT), Parkinson's Disease Questionnaire (PDQ39), fall efficacy scale (FES-I), and timed up and go test (TUG). All outcomes were assessed at baseline, after training, and at 1-month follow-up. The VRWii group showed greater improvement in obstacle crossing velocity, crossing stride length, dynamic balance, SOT, TUG, FES-I, and PDQ39 than the control group. VRWii training also resulted in greater improvement in movement velocity of limits-of-stability test than TE training. VRWii training significantly improved obstacle crossing performance and dynamic balance, supporting implementation of VRWii training in participants with PD. © The Author(s) 2014.

  13. Range Sensor-Based Efficient Obstacle Avoidance through Selective Decision-Making.

    PubMed

    Shim, Youngbo; Kim, Gon-Woo

    2018-03-29

    In this paper, we address a collision avoidance method for mobile robots. Many conventional obstacle avoidance methods have been focused solely on avoiding obstacles. However, this can cause instability when passing through a narrow passage, and can also generate zig-zag motions. We define two strategies for obstacle avoidance, known as Entry mode and Bypass mode. Entry mode is a pattern for passing through the gap between obstacles, while Bypass mode is a pattern for making a detour around obstacles safely. With these two modes, we propose an efficient obstacle avoidance method based on the Expanded Guide Circle (EGC) method with selective decision-making. The simulation and experiment results show the validity of the proposed method.

  14. Method for surmounting an obstacle by a robot vehicle

    NASA Technical Reports Server (NTRS)

    Wilcox, Brian H. (Inventor); Ohm, Timothy R. (Inventor)

    1994-01-01

    Surmounting obstacles in the path of a robot vehicle is accomplished by rotating the wheel forks of the vehicle about their transverse axes with respect to the vehicle body so as to shift most of the vehicle weight onto the rear wheels, and then driving the vehicle forward so as to drive the now lightly-loaded front wheels (only) over the obstacle. Then, after the front wheels have either surmounted or completely passed the obstacle (depending upon the length of the obstacle), the forks are again rotated about their transverse axes so as to shift most of the vehicle weight onto the front wheels. Then the vehicle is again driven forward so as to drive the now lightly-loaded rear wheels over the obstacle. Once the obstacle has been completely cleared and the vehicle is again on relatively level terrain, the forks are again rotated so as to uniformly distribute the vehicle weight between the front and rear wheels.

  15. Statistical Analysis of Temple Orientation in Ancient India

    NASA Astrophysics Data System (ADS)

    Aller, Alba; Belmonte, Juan Antonio

    2015-05-01

    The great diversity of religions that have been followed in India for over 3000 years is the reason why there are hundreds of temples built to worship dozens of different divinities. In this work, more than one hundred temples geographically distributed over the whole Indian land have been analyzed, obtaining remarkable results. For this purpose, a deep analysis of the main deities who are worshipped in each of them, as well as of the different dynasties (or cultures) who built them has also been conducted. As a result, we have found that the main axes of the temples dedicated to Shiva seem to be oriented to the east cardinal point while those temples dedicated to Vishnu would be oriented to both the east and west cardinal points. To explain these cardinal directions we propose to look back to the origins of Hinduism. Besides these cardinal orientations, clear solar orientations have also been found, especially at the equinoctial declination.

  16. Evolutionary programming-based univector field navigation method for past mobile robots.

    PubMed

    Kim, Y J; Kim, J H; Kwon, D S

    2001-01-01

    Most of navigation techniques with obstacle avoidance do not consider the robot orientation at the target position. These techniques deal with the robot position only and are independent of its orientation and velocity. To solve these problems this paper proposes a novel univector field method for fast mobile robot navigation which introduces a normalized two dimensional vector field. The method provides fast moving robots with the desired posture at the target position and obstacle avoidance. To obtain the sub-optimal vector field, a function approximator is used and trained by evolutionary programming. Two kinds of vector fields are trained, one for the final posture acquisition and the other for obstacle avoidance. Computer simulations and real experiments are carried out for a fast moving mobile robot to demonstrate the effectiveness of the proposed scheme.

  17. Evacuation simulation with consideration of obstacle removal and using game theory

    NASA Astrophysics Data System (ADS)

    Lin, Guan-Wen; Wong, Sai-Keung

    2018-06-01

    In this paper, we integrate a cellular automaton model with game theory to simulate crowd evacuation from a room with consideration of obstacle removal. The room has one or more exits, one of which is blocked by obstacles. The obstacles at the exit can be removed by volunteers. We investigate the cooperative and defective behaviors of pedestrians during evacuation. The yielder game and volunteer's dilemma game are employed to resolve interpedestrian conflict. An anticipation floor field is proposed to guide the pedestrians to avoid obstacles that are being removed. We conducted experiments to determine how a variety of conditions affect overall crowd evacuation and volunteer evacuation times. The conditions were the start time of obstacle removal, number of obstacles, placement of obstacles, time spent in obstacle removal, strength of the anticipation floor field, and obstacle visibility distance. We demonstrate how reciprocity can be achieved among pedestrians and increases the efficiency of the entire evacuation process.

  18. An Algorithm for Autonomous Formation Obstacle Avoidance

    NASA Astrophysics Data System (ADS)

    Cruz, Yunior I.

    The level of human interaction with Unmanned Aerial Systems varies greatly from remotely piloted aircraft to fully autonomous systems. In the latter end of the spectrum, the challenge lies in designing effective algorithms to dictate the behavior of the autonomous agents. A swarm of autonomous Unmanned Aerial Vehicles requires collision avoidance and formation flight algorithms to negotiate environmental challenges it may encounter during the execution of its mission, which may include obstacles and chokepoints. In this work, a simple algorithm is developed to allow a formation of autonomous vehicles to perform point to point navigation while avoiding obstacles and navigating through chokepoints. Emphasis is placed on maintaining formation structures. Rather than breaking formation and individually navigating around the obstacle or through the chokepoint, vehicles are required to assemble into appropriately sized/shaped sub-formations, bifurcate around the obstacle or negotiate the chokepoint, and reassemble into the original formation at the far side of the obstruction. The algorithm receives vehicle and environmental properties as inputs and outputs trajectories for each vehicle from start to the desired ending location. Simulation results show that the algorithm safely routes all vehicles past the obstruction while adhering to the aforementioned requirements. The formation adapts and successfully negotiates the obstacles and chokepoints in its path while maintaining proper vehicle separation.

  19. Prefrontal cortex activation during obstacle negotiation: What's the effect size and timing?

    PubMed

    Maidan, Inbal; Shustak, Shiran; Sharon, Topaz; Bernad-Elazari, Hagar; Geffen, Nimrod; Giladi, Nir; Hausdorff, Jeffrey M; Mirelman, Anat

    2018-04-01

    Obstacle negotiation is a daily activity that requires the integration of sensorimotor and cognitive information. Recent studies provide evidence for the important role of prefrontal cortex during obstacle negotiation. We aimed to explore the effects of obstacle height and available response time on prefrontal activation. Twenty healthy young adults (age: 30.1 ± 1.0 years; 50% women) walked in an obstacle course while negotiating anticipated and unanticipated obstacles at heights of 50 mm and 100 mm. Prefrontal activation was measured using a functional near-infrared spectroscopy system. Kinect cameras measured the obstacle negotiation strategy. Prefrontal activation was defined based on mean level of HbO 2 before, during and after obstacle negotiation and the HbO 2 slope from gait initiation and throughout the task. Changes between types of obstacles were assessed using linear-mix models and partial correlation analyses evaluated the relationship between prefrontal activation and the distance between the feet as the subjects traversed the obstacles. Different obstacle heights showed similar changes in prefrontal activation measures (p > 0.210). However, during unanticipated obstacles, the slope of the HbO 2 response was steeper (p = 0.048), as compared to anticipated obstacles. These changes in prefrontal activation during negotiation of unanticipated obstacles were correlated with greater distance of the leading foot after the obstacles (r = 0.831, p = 0.041). These findings are the first to show that the pattern of prefrontal activation depends on the nature of the obstacle. More specifically, during unanticipated obstacles the recruitment of the prefrontal cortex is faster and greater than during negotiating anticipated obstacles. These results provide evidence of the important role of the prefrontal cortex and the ability of healthy young adults to tailor the activation pattern to different types of obstacles. Copyright © 2018

  20. [Therapeutic education in pediatric dentistry: analysis of obstacles and levers to the development of programmes in France in 2016].

    PubMed

    Marquillier, Thomas; Trentesaux, Thomas; Gagnayre, Rémi

    2017-01-01

    Over recent years, therapeutic patient education has become part of dental medicine. Management of early childhood caries, known to be a very common chronic disease, has evolved to include an educational dimension. The objective of this study was to identify the levers and barriers to the development of formalized therapeutic education programmes and alternatives. A comprehensive exploratory qualitative study was conducted between November 2015 and June 2016 on a targeted sample of 15 people aware of the problem of TPE in dentistry. The study showed that TPE training in dentistry is underdeveloped, despite its numerous benefits: change of the healthcare professional's approach, implementation of structured educational programmes, development of research, etc. There are many obstacles to the development of TPE programmes: insufficient resources, rigid legislation or lack of knowledge of TPE practices. The dental profession is an obstacle itself because of its lack of understanding and variable degrees of integration the medical community. There are multiple levers, but the main ones are changing attitudes of the profession and the provision of resources to develop TPE. Although alternatives to TPE programmes exist (accompanying measures, short educational strategies, connected health), they cannot replace TPE. More educational strategies must be developed in the field of dentistry. However, the framework of TPE must be adapted to the profession to ensure good uptake.

  1. Spontaneous in-flight accommodation of hand orientation to unseen grasp targets: A case of action blindsight.

    PubMed

    Prentiss, Emily K; Schneider, Colleen L; Williams, Zoë R; Sahin, Bogachan; Mahon, Bradford Z

    2018-03-15

    The division of labour between the dorsal and ventral visual pathways is well established. The ventral stream supports object identification, while the dorsal stream supports online processing of visual information in the service of visually guided actions. Here, we report a case of an individual with a right inferior quadrantanopia who exhibited accurate spontaneous rotation of his wrist when grasping a target object in his blind visual field. His accurate wrist orientation was observed despite the fact that he exhibited no sensitivity to the orientation of the handle in a perceptual matching task. These findings indicate that non-geniculostriate visual pathways process basic volumetric information relevant to grasping, and reinforce the observation that phenomenal awareness is not necessary for an object's volumetric properties to influence visuomotor performance.

  2. Student with Asperger's Overcomes Obstacles: Devon's Journey to Independence

    ERIC Educational Resources Information Center

    Williams, Sarah Blackwelder

    2010-01-01

    Devon is a bright, engaging 22-year-old with a proud sense of accomplishment. He believes that while people encounter obstacles during their lives, these obstacles can be overcome with motivation and perseverance. Devon says people simply need to identify what they value, set goals and move beyond the obstacles. Devon has been faced with multiple…

  3. Simulation of Molecular Transport in Systems Containing Mobile Obstacles.

    PubMed

    Polanowski, Piotr; Sikorski, Andrzej

    2016-08-04

    In this paper, we investigate the movement of molecules in crowded environments with obstacles undergoing Brownian motion by means of extensive Monte Carlo simulations. Our investigations were performed using the dynamic lattice liquid model, which was based on the cooperative movement concept and allowed to mimic systems at high densities where the motion of all elements (obstacles as well as moving particles) were highly correlated. The crowded environments are modeled on a two-dimensional triangular lattice containing obstacles (particles whose mobility was significantly reduced) moving by a Brownian motion. The subdiffusive motion of both elements in the system was analyzed. It was shown that the percolation transition does not exist in such systems in spite of the cooperative character of the particles' motion. The reduction of the obstacle mobility leads to the longer caging of liquid particles by mobile obstacles.

  4. Diffusion amid random overlapping obstacles: Similarities, invariants, approximations

    PubMed Central

    Novak, Igor L.; Gao, Fei; Kraikivski, Pavel; Slepchenko, Boris M.

    2011-01-01

    Efficient and accurate numerical techniques are used to examine similarities of effective diffusion in a void between random overlapping obstacles: essential invariance of effective diffusion coefficients (Deff) with respect to obstacle shapes and applicability of a two-parameter power law over nearly entire range of excluded volume fractions (ϕ), except for a small vicinity of a percolation threshold. It is shown that while neither of the properties is exact, deviations from them are remarkably small. This allows for quick estimation of void percolation thresholds and approximate reconstruction of Deff (ϕ) for obstacles of any given shape. In 3D, the similarities of effective diffusion yield a simple multiplication “rule” that provides a fast means of estimating Deff for a mixture of overlapping obstacles of different shapes with comparable sizes. PMID:21513372

  5. Age-associated changes in obstacle negotiation strategies: Does size and timing matter?

    PubMed

    Maidan, I; Eyal, S; Kurz, I; Geffen, N; Gazit, E; Ravid, L; Giladi, N; Mirelman, A; Hausdorff, J M

    2018-01-01

    Tripping over an obstacle is one of the most common causes of falls among older adults. However, the effects of aging, obstacle height and anticipation time on negotiation strategies have not been systematically evaluated. Twenty older adults (ages: 77.7±3.4years; 50% women) and twenty young adults (age: 29.3±3.8years; 50% women) walked through an obstacle course while negotiating anticipated and unanticipated obstacles at heights of 25mm and 75mm. Kinect cameras captured the: (1) distance of the subject's trailing foot before the obstacles, (2) distance of the leading foot after the obstacles, (3) clearance of the leading foot above the obstacles, and (4) clearance of the trailing foot above the obstacles. Linear-mix models assessed changes between groups and conditions. Older adults placed their leading foot closer to the obstacle after landing, compared to young adults (p<0.001). This pattern was enhanced in high obstacles (group*height interaction, p=0.033). Older adults had lower clearance over the obstacles, compared to young adults (p=0.007). This was more pronounced during unanticipated obstacles (group*ART interaction, p=0.003). The distance of the leading foot and clearance of the trailing foot after the obstacles were correlated with motor, cognitive, and functional abilities. These findings suggest that there are age-related changes in obstacle crossing strategies that are dependent on the specific characteristics of the obstacle. The results have important implications for clinical practice, suggesting that functional exercise should include obstacle negotiation training with variable practice of height and available response times. Further studies are needed to better understand the effects of motor and cognitive abilities. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Bond-orientational analysis of hard-disk and hard-sphere structures.

    PubMed

    Senthil Kumar, V; Kumaran, V

    2006-05-28

    We report the bond-orientational analysis results for the thermodynamic, random, and homogeneously sheared inelastic structures of hard-disks and hard-spheres. The thermodynamic structures show a sharp rise in the order across the freezing transition. The random structures show the absence of crystallization. The homogeneously sheared structures get ordered at a packing fraction higher than the thermodynamic freezing packing fraction, due to the suppression of crystal nucleation. On shear ordering, strings of close-packed hard-disks in two dimensions and close-packed layers of hard-spheres in three dimensions, oriented along the velocity direction, slide past each other. Such a flow creates a considerable amount of fourfold order in two dimensions and body-centered-tetragonal (bct) structure in three dimensions. These transitions are the flow analogs of the martensitic transformations occurring in metals due to the stresses induced by a rapid quench. In hard-disk structures, using the bond-orientational analysis we show the presence of fourfold order. In sheared inelastic hard-sphere structures, even though the global bond-orientational analysis shows that the system is highly ordered, a third-order rotational invariant analysis shows that only about 40% of the spheres have face-centered-cubic (fcc) order, even in the dense and near-elastic limits, clearly indicating the coexistence of multiple crystalline orders. When layers of close-packed spheres slide past each other, in addition to the bct structure, the hexagonal-close-packed (hcp) structure is formed due to the random stacking faults. Using the Honeycutt-Andersen pair analysis and an analysis based on the 14-faceted polyhedra having six quadrilateral and eight hexagonal faces, we show the presence of bct and hcp signatures in shear ordered inelastic hard-spheres. Thus, our analysis shows that the dense sheared inelastic hard-spheres have a mixture of fcc, bct, and hcp structures.

  7. Epistemological Obstacles on the Topic of Ratio and Proportion among Junior High School Students

    NASA Astrophysics Data System (ADS)

    Wahyuningrum, A. S.; Suryadi, D.; Turmudi

    2017-09-01

    This study intends to investigate how students’ understanding of ratio and proportion concept indicates epistemological obstacles. It was part of Didactical Design Research which was conducted to 72 students of 8th grade who ever learned about ratio and proportion. Data were collected through the students’ answers and interview in solving ratio and proportion problems. The results show that students’ conception, the ways of applying other mathematical concepts, the ways of using the rules, and variety of contexts are factors influencing epistemological obstacles in teaching and learning of ratio and proportion. These conditions can affect the students’ understanding o f related mathematics topics. Based on analysis of the results, this study is expected to overcome or minimize the epistemological obstacles.

  8. Audible sonar images generated with proprioception for target analysis.

    PubMed

    Kuc, Roman B

    2017-05-01

    Some blind humans have demonstrated the ability to detect and classify objects with echolocation using palatal clicks. An audible-sonar robot mimics human click emissions, binaural hearing, and head movements to extract interaural time and level differences from target echoes. Targets of various complexity are examined by transverse displacements of the sonar and by target pose rotations that model movements performed by the blind. Controlled sonar movements executed by the robot provide data that model proprioception information available to blind humans for examining targets from various aspects. The audible sonar uses this sonar location and orientation information to form two-dimensional target images that are similar to medical diagnostic ultrasound tomograms. Simple targets, such as single round and square posts, produce distinguishable and recognizable images. More complex targets configured with several simple objects generate diffraction effects and multiple reflections that produce image artifacts. The presentation illustrates the capabilities and limitations of target classification from audible sonar images.

  9. Obstacle negotiation control for a mobile robot suspended on overhead ground wires by optoelectronic sensors

    NASA Astrophysics Data System (ADS)

    Zheng, Li; Yi, Ruan

    2009-11-01

    Power line inspection and maintenance already benefit from developments in mobile robotics. This paper presents mobile robots capable of crossing obstacles on overhead ground wires. A teleoperated robot realizes inspection and maintenance tasks on power transmission line equipment. The inspection robot is driven by 11 motor with two arms, two wheels and two claws. The inspection robot is designed to realize the function of observation, grasp, walk, rolling, turn, rise, and decline. This paper is oriented toward 100% reliable obstacle detection and identification, and sensor fusion to increase the autonomy level. An embedded computer based on PC/104 bus is chosen as the core of control system. Visible light camera and thermal infrared Camera are both installed in a programmable pan-and-tilt camera (PPTC) unit. High-quality visual feedback rapidly becomes crucial for human-in-the-loop control and effective teleoperation. The communication system between the robot and the ground station is based on Mesh wireless networks by 700 MHz bands. An expert system programmed with Visual C++ is developed to implement the automatic control. Optoelectronic laser sensors and laser range scanner were installed in robot for obstacle-navigation control to grasp the overhead ground wires. A novel prototype with careful considerations on mobility was designed to inspect the 500KV power transmission lines. Results of experiments demonstrate that the robot can be applied to execute the navigation and inspection tasks.

  10. Overcoming obstacles to behavior change in diabetes self-management.

    PubMed

    Hall, Rosemary F; Joseph, Dayle Hunt; Schwartz-Barcott, Donna

    2003-01-01

    This study describes how 5 individuals with type 2 diabetes overcame obstacles that interfered with maintaining behavior changes in diet, exercise, and self-monitoring of blood glucose (SMBG). In-depth interviews provided the framework for this descriptive study. During audiotaped, face-to-face, follow-up structured and unstructured interviews, the participants shared their experiences about obstacles encountered and strategies used to overcome them. Each case was examined independently, and all cases were then compared with each other. Obstacles that interfered with maintaining a diet plan were hunger, planned and unplanned meal events, and the desire for new foods. Physical illness and unexpected life events were obstacles to maintaining an exercise and SMBG plan. Health professionals who assist patients who are beginning behavior change or having difficult maintaining changes need to have an understanding of the various obstacles and how patients can maintain behavior changes over time.

  11. Obstacle avoidance handling and mixed integer predictive control for space robots

    NASA Astrophysics Data System (ADS)

    Zong, Lijun; Luo, Jianjun; Wang, Mingming; Yuan, Jianping

    2018-04-01

    This paper presents a novel obstacle avoidance constraint and a mixed integer predictive control (MIPC) method for space robots avoiding obstacles and satisfying physical limits during performing tasks. Firstly, a novel kind of obstacle avoidance constraint of space robots, which needs the assumption that the manipulator links and the obstacles can be represented by convex bodies, is proposed by limiting the relative velocity between two closest points which are on the manipulator and the obstacle, respectively. Furthermore, the logical variables are introduced into the obstacle avoidance constraint, which have realized the constraint form is automatically changed to satisfy different obstacle avoidance requirements in different distance intervals between the space robot and the obstacle. Afterwards, the obstacle avoidance constraint and other system physical limits, such as joint angle ranges, the amplitude boundaries of joint velocities and joint torques, are described as inequality constraints of a quadratic programming (QP) problem by using the model predictive control (MPC) method. To guarantee the feasibility of the obtained multi-constraint QP problem, the constraints are treated as soft constraints and assigned levels of priority based on the propositional logic theory, which can realize that the constraints with lower priorities are always firstly violated to recover the feasibility of the QP problem. Since the logical variables have been introduced, the optimization problem including obstacle avoidance and system physical limits as prioritized inequality constraints is termed as MIPC method of space robots, and its computational complexity as well as possible strategies for reducing calculation amount are analyzed. Simulations of the space robot unfolding its manipulator and tracking the end-effector's desired trajectories with the existence of obstacles and physical limits are presented to demonstrate the effectiveness of the proposed obstacle avoidance

  12. An enhanced obstacle avoiding system for AUV`s

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

    Conte, G.; Zanoli, S.M.

    1994-12-31

    This paper concerns the development of a sonar-based navigation and guidance system for underwater, unmanned vehicles. In particular, the authors describe and discuss an obstacle avoidance procedure that is capable of dealing with situations involving several obstacles. The main features of the system are the use of a Kalman filter, both for estimating data and for predicting the evolution of the observed scene, and the possibility of working at different levels of data abstraction. The system has shown satisfactory performances in dealing with moving obstacles in general situations.

  13. FieldSAFE: Dataset for Obstacle Detection in Agriculture.

    PubMed

    Kragh, Mikkel Fly; Christiansen, Peter; Laursen, Morten Stigaard; Larsen, Morten; Steen, Kim Arild; Green, Ole; Karstoft, Henrik; Jørgensen, Rasmus Nyholm

    2017-11-09

    In this paper, we present a multi-modal dataset for obstacle detection in agriculture. The dataset comprises approximately 2 h of raw sensor data from a tractor-mounted sensor system in a grass mowing scenario in Denmark, October 2016. Sensing modalities include stereo camera, thermal camera, web camera, 360 ∘ camera, LiDAR and radar, while precise localization is available from fused IMU and GNSS. Both static and moving obstacles are present, including humans, mannequin dolls, rocks, barrels, buildings, vehicles and vegetation. All obstacles have ground truth object labels and geographic coordinates.

  14. FieldSAFE: Dataset for Obstacle Detection in Agriculture

    PubMed Central

    Christiansen, Peter; Larsen, Morten; Steen, Kim Arild; Green, Ole; Karstoft, Henrik

    2017-01-01

    In this paper, we present a multi-modal dataset for obstacle detection in agriculture. The dataset comprises approximately 2 h of raw sensor data from a tractor-mounted sensor system in a grass mowing scenario in Denmark, October 2016. Sensing modalities include stereo camera, thermal camera, web camera, 360∘ camera, LiDAR and radar, while precise localization is available from fused IMU and GNSS. Both static and moving obstacles are present, including humans, mannequin dolls, rocks, barrels, buildings, vehicles and vegetation. All obstacles have ground truth object labels and geographic coordinates. PMID:29120383

  15. Motion Among Random Obstacles on a Hyperbolic Space

    NASA Astrophysics Data System (ADS)

    Orsingher, Enzo; Ricciuti, Costantino; Sisti, Francesco

    2016-02-01

    We consider the motion of a particle along the geodesic lines of the Poincaré half-plane. The particle is specularly reflected when it hits randomly-distributed obstacles that are assumed to be motionless. This is the hyperbolic version of the well-known Lorentz Process studied in the Euclidean context. We analyse the limit in which the density of the obstacles increases to infinity and the size of each obstacle vanishes: under a suitable scaling, we prove that our process converges to a Markovian process, namely a random flight on the hyperbolic manifold.

  16. Multicamera polarized vision for the orientation with the skylight polarization patterns

    NASA Astrophysics Data System (ADS)

    Fan, Chen; Hu, Xiaoping; He, Xiaofeng; Zhang, Lilian; Wang, Yujie

    2018-04-01

    A robust orientation algorithm based on the skylight polarization patterns for the urban ground vehicle is presented. We present the orientation model with the Rayleigh scattering and propose the robust orientation algorithm with the total least square. The proposed algorithm can utilize the whole sky area polarization patterns for realizing a more robust and accurate orientation. To enhance the algorithm's robustness in the urban environment, we develop a real-time method that uses the gradient of the degree of the polarization to remove the obstacles in the polarization image. In addition, our algorithm can solve the ambiguity problem of the polarized orientation without any other sensors. We also conduct a static rotating and a dynamic car experiments to evaluate the algorithm. The results demonstrate that our proposed algorithm can provide an accurate orientation estimation for the ground vehicle in the open and urban environments-the root-mean-square error in the static experiment is 0.28 deg and in the dynamic experiment is 0.81 deg. Finally, we discuss insights gained with respect to further work in optics and robotics.

  17. A reciprocity formulation for the EM scattering by an obstacle within a large open cavity

    NASA Technical Reports Server (NTRS)

    Pathak, Prabhakar H.; Burkholder, Robert J.

    1993-01-01

    A formulation based on a generalized reciprocity theorem is developed for analyzing the external high frequency EM scattering by a complex obstacle inside a relatively arbitrary open-ended waveguide cavity when it is illuminated by an external source. This formulation is also extended to include EM fields whose time dependence may be nonperiodic. A significant advantage of this formulation is that it allows one to break up the analysis into two independent parts; one deals with the waveguide cavity shape alone and the other with the obstacle alone. The external scattered field produced by the obstacle (in the presence of the waveguide cavity structure) is given in terms of a generalized reciprocity integral over a surface S(T) corresponding to the interior waveguide cavity cross section located conveniently but sufficiently close to the obstacle. Furthermore, the fields coupled into the cavity from the source in the exterior region generally need to propagate only one-way via the open front end (which is directly illuminated) to the interior surface S(T) in this approach, and not back, in order to find the external field scattered by the obstacle.

  18. Knowing where is different from knowing what: Distinct response time profiles and accuracy effects for target location, orientation, and color probability.

    PubMed

    Jabar, Syaheed B; Filipowicz, Alex; Anderson, Britt

    2017-11-01

    When a location is cued, targets appearing at that location are detected more quickly. When a target feature is cued, targets bearing that feature are detected more quickly. These attentional cueing effects are only superficially similar. More detailed analyses find distinct temporal and accuracy profiles for the two different types of cues. This pattern parallels work with probability manipulations, where both feature and spatial probability are known to affect detection accuracy and reaction times. However, little has been done by way of comparing these effects. Are probability manipulations on space and features distinct? In a series of five experiments, we systematically varied spatial probability and feature probability along two dimensions (orientation or color). In addition, we decomposed response times into initiation and movement components. Targets appearing at the probable location were reported more quickly and more accurately regardless of whether the report was based on orientation or color. On the other hand, when either color probability or orientation probability was manipulated, response time and accuracy improvements were specific for that probable feature dimension. Decomposition of the response time benefits demonstrated that spatial probability only affected initiation times, whereas manipulations of feature probability affected both initiation and movement times. As detection was made more difficult, the two effects further diverged, with spatial probability disproportionally affecting initiation times and feature probability disproportionately affecting accuracy. In conclusion, all manipulations of probability, whether spatial or featural, affect detection. However, only feature probability affects perceptual precision, and precision effects are specific to the probable attribute.

  19. Perceived Sexual Orientation Based on Vocal and Facial Stimuli Is Linked to Self-Rated Sexual Orientation in Czech Men

    PubMed Central

    Valentova, Jaroslava Varella; Havlíček, Jan

    2013-01-01

    Previous research has shown that lay people can accurately assess male sexual orientation based on limited information, such as face, voice, or behavioral display. Gender-atypical traits are thought to serve as cues to sexual orientation. We investigated the presumed mechanisms of sexual orientation attribution using a standardized set of facial and vocal stimuli of Czech men. Both types of stimuli were rated for sexual orientation and masculinity-femininity by non-student heterosexual women and homosexual men. Our data showed that by evaluating vocal stimuli both women and homosexual men can judge sexual orientation of the target men in agreement with their self-reported sexual orientation. Nevertheless, only homosexual men accurately attributed sexual orientation of the two groups from facial images. Interestingly, facial images of homosexual targets were rated as more masculine than heterosexual targets. This indicates that attributions of sexual orientation are affected by stereotyped association between femininity and male homosexuality; however, reliance on such cues can lead to frequent misjudgments as was the case with the female raters. Although our study is based on a community sample recruited in a non-English speaking country, the results are generally consistent with the previous research and thus corroborate the validity of sexual orientation attributions. PMID:24358180

  20. LLNL Scientist is Passionate About Targets

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

    Butlin, Becky

    With a lifelong passion for problem-solving and a love of production, Becky Butlin has helped lead the National Ignition Facility Target Fabrication Team through obstacles and challenges for the past six years.

  1. Relationship between Target Orientations and Perceived Motivational Climate Levels of Students Engaged in Individual and Team Sports Activities

    ERIC Educational Resources Information Center

    Arslanoglu, Cansel

    2016-01-01

    The aim of this study is to analyze the relationship between perceived motivational climate and target orientations of team and individual athletes who participate in sports at the Physical Education and Sports Departments of faculties. A total of 200 athletes (students at the Physical Education and Sports Departments of Gazi University, Selçuk…

  2. Stepping back to see the big picture: when obstacles elicit global processing.

    PubMed

    Marguc, Janina; Förster, Jens; Van Kleef, Gerben A

    2011-11-01

    Can obstacles prompt people to look at the "big picture" and open up their minds? Do the cognitive effects of obstacles extend beyond the tasks with which they interfere? These questions were addressed in 6 studies involving both physical and nonphysical obstacles and different measures of global versus local processing styles. Perceptual scope increased after participants solved anagrams in the presence, rather than the absence, of an auditory obstacle (random words played in the background; Study 1), particularly among individuals low in volatility (i.e., those who are inclined to stay engaged and finish what they do; Study 4). It also increased immediately after participants encountered a physical obstacle while navigating a maze (Study 3A) and when compared with doing nothing (Study 3B). Conceptual scope increased after participants solved anagrams while hearing random numbers framed as an "obstacle to overcome" rather than a "distraction to ignore" (Study 2) and after participants navigated a maze with a physical obstacle, compared with a maze without a physical obstacle, but only when trait (Study 5) or state (Study 6) volatility was low. Results suggest that obstacles trigger an "if obstacle, then start global processing" response, primarily when people are inclined to stay engaged and finish ongoing activities. Implications for dealing with life's obstacles and related research are discussed.

  3. Using Thermal Radiation in Detection of Negative Obstacles

    NASA Technical Reports Server (NTRS)

    Rankin, Arturo L.; Matthies, Larry H.

    2009-01-01

    A method of automated detection of negative obstacles (potholes, ditches, and the like) ahead of ground vehicles at night involves processing of imagery from thermal-infrared cameras aimed at the terrain ahead of the vehicles. The method is being developed as part of an overall obstacle-avoidance scheme for autonomous and semi-autonomous offroad robotic vehicles. The method could also be applied to help human drivers of cars and trucks avoid negative obstacles -- a development that may entail only modest additional cost inasmuch as some commercially available passenger cars are already equipped with infrared cameras as aids for nighttime operation.

  4. Cross-orientation suppression in human visual cortex

    PubMed Central

    Heeger, David J.

    2011-01-01

    Cross-orientation suppression was measured in human primary visual cortex (V1) to test the normalization model. Subjects viewed vertical target gratings (of varying contrasts) with or without a superimposed horizontal mask grating (fixed contrast). We used functional magnetic resonance imaging (fMRI) to measure the activity in each of several hypothetical channels (corresponding to subpopulations of neurons) with different orientation tunings and fit these orientation-selective responses with the normalization model. For the V1 channel maximally tuned to the target orientation, responses increased with target contrast but were suppressed when the horizontal mask was added, evident as a shift in the contrast gain of this channel's responses. For the channel maximally tuned to the mask orientation, a constant baseline response was evoked for all target contrasts when the mask was absent; responses decreased with increasing target contrast when the mask was present. The normalization model provided a good fit to the contrast-response functions with and without the mask. In a control experiment, the target and mask presentations were temporally interleaved, and we found no shift in contrast gain, i.e., no evidence for suppression. We conclude that the normalization model can explain cross-orientation suppression in human visual cortex. The approach adopted here can be applied broadly to infer, simultaneously, the responses of several subpopulations of neurons in the human brain that span particular stimulus or feature spaces, and characterize their interactions. In addition, it allows us to investigate how stimuli are represented by the inferred activity of entire neural populations. PMID:21775720

  5. Sensorimotor integration of vision and proprioception for obstacle crossing in ambulatory individuals with spinal cord injury.

    PubMed

    Malik, Raza Naseem; Cote, Rachel; Lam, Tania

    2017-01-01

    Skilled walking, such as obstacle crossing, is an essential component of functional mobility. Sensorimotor integration of visual and proprioceptive inputs is important for successful obstacle crossing. The objective of this study was to understand how proprioceptive deficits affect obstacle-crossing strategies when controlling for variations in motor deficits in ambulatory individuals with spinal cord injury (SCI). Fifteen ambulatory individuals with SCI and 15 able-bodied controls were asked to step over an obstacle scaled to their motor abilities under full and obstructed vision conditions. An eye tracker was used to determine gaze behaviour and motion capture analysis was used to determine toe kinematics relative to the obstacle. Combined, bilateral hip and knee proprioceptive sense (joint position sense and movement detection sense) was assessed using the Lokomat and customized software controls. Combined, bilateral hip and knee proprioceptive sense in subjects with SCI varied and was significantly different from able-bodied subjects. Subjects with greater proprioceptive deficits stepped higher over the obstacle with their lead and trail limbs in the obstructed vision condition compared with full vision. Subjects with SCI also glanced at the obstacle more frequently and with longer fixation times compared with controls, but this was not related to proprioceptive sense. This study indicates that ambulatory individuals with SCI rely more heavily on vision to cross obstacles and show impairments in key gait parameters required for successful obstacle crossing. Our data suggest that proprioceptive deficits need to be considered in rehabilitation programs aimed at improving functional mobility in ambulatory individuals with SCI. This work is unique since it examines the contribution of combined, bilateral hip and knee proprioceptive sense on the recovery of skilled walking function, in addition to characterizing gaze behavior during a skilled walking task in people

  6. Joint Doctrine for Barriers, Obstacles, and Mine Warfare

    DTIC Science & Technology

    1999-02-24

    of explosives. Typical tactical examples are barbed wire obstacles and tank ditches. Operational and strategic barriers and obstacles may also be...total of 10 ocean minesweepers, 9 amphibious ships, 6 fleet tugs, 3 salvage ships, and 19 destroyers. Twenty-four CH-53D Sea Stallions from Marine

  7. How Obstacles Perturb Population Fronts and Alter Their Genetic Structure.

    PubMed

    Möbius, Wolfram; Murray, Andrew W; Nelson, David R

    2015-12-01

    As populations spread into new territory, environmental heterogeneities can shape the population front and genetic composition. We focus here on the effects of an important building block of heterogeneous environments, isolated obstacles. With a combination of experiments, theory, and simulation, we show how isolated obstacles both create long-lived distortions of the front shape and amplify the effect of genetic drift. A system of bacteriophage T7 spreading on a spatially heterogeneous Escherichia coli lawn serves as an experimental model system to study population expansions. Using an inkjet printer, we create well-defined replicates of the lawn and quantitatively study the population expansion of phage T7. The transient perturbations of the population front found in the experiments are well described by a model in which the front moves with constant speed. Independent of the precise details of the expansion, we show that obstacles create a kink in the front that persists over large distances and is insensitive to the details of the obstacle's shape. The small deviations between experimental findings and the predictions of the constant speed model can be understood with a more general reaction-diffusion model, which reduces to the constant speed model when the obstacle size is large compared to the front width. Using this framework, we demonstrate that frontier genotypes just grazing the side of an isolated obstacle increase in abundance, a phenomenon we call 'geometry-enhanced genetic drift', complementary to the founder effect associated with spatial bottlenecks. Bacterial range expansions around nutrient-poor barriers and stochastic simulations confirm this prediction. The effect of the obstacle on the genealogy of individuals at the front is characterized by simulations and rationalized using the constant speed model. Lastly, we consider the effect of two obstacles on front shape and genetic composition of the population illuminating the effects expected from

  8. Research on UAV Intelligent Obstacle Avoidance Technology During Inspection of Transmission Line

    NASA Astrophysics Data System (ADS)

    Wei, Chuanhu; Zhang, Fei; Yin, Chaoyuan; Liu, Yue; Liu, Liang; Li, Zongyu; Wang, Wanguo

    Autonomous obstacle avoidance of unmanned aerial vehicle (hereinafter referred to as UAV) in electric power line inspection process has important significance for operation safety and economy for UAV intelligent inspection system of transmission line as main content of UAV intelligent inspection system on transmission line. In the paper, principles of UAV inspection obstacle avoidance technology of transmission line are introduced. UAV inspection obstacle avoidance technology based on particle swarm global optimization algorithm is proposed after common obstacle avoidance technologies are studied. Stimulation comparison is implemented with traditional UAV inspection obstacle avoidance technology which adopts artificial potential field method. Results show that UAV inspection strategy of particle swarm optimization algorithm, adopted in the paper, is prominently better than UAV inspection strategy of artificial potential field method in the aspects of obstacle avoidance effect and the ability of returning to preset inspection track after passing through the obstacle. An effective method is provided for UAV inspection obstacle avoidance of transmission line.

  9. Collective strategy for obstacle navigation during cooperative transport by ants.

    PubMed

    McCreery, Helen F; Dix, Zachary A; Breed, Michael D; Nagpal, Radhika

    2016-11-01

    Group cohesion and consensus have primarily been studied in the context of discrete decisions, but some group tasks require making serial decisions that build on one another. We examine such collective problem solving by studying obstacle navigation during cooperative transport in ants. In cooperative transport, ants work together to move a large object back to their nest. We blocked cooperative transport groups of Paratrechina longicornis with obstacles of varying complexity, analyzing groups' trajectories to infer what kind of strategy the ants employed. Simple strategies require little information, but more challenging, robust strategies succeed with a wider range of obstacles. We found that transport groups use a stochastic strategy that leads to efficient navigation around simple obstacles, and still succeeds at difficult obstacles. While groups navigating obstacles preferentially move directly toward the nest, they change their behavior over time; the longer the ants are obstructed, the more likely they are to move away from the nest. This increases the chance of finding a path around the obstacle. Groups rapidly changed directions and rarely stalled during navigation, indicating that these ants maintain consensus even when the nest direction is blocked. Although some decisions were aided by the arrival of new ants, at many key points, direction changes were initiated within the group, with no apparent external cause. This ant species is highly effective at navigating complex environments, and implements a flexible strategy that works for both simple and more complex obstacles. © 2016. Published by The Company of Biologists Ltd.

  10. Collision-based energetic comparison of rolling and hopping over obstacles

    PubMed Central

    Iida, Fumiya

    2018-01-01

    Locomotion of machines and robots operating in rough terrain is strongly influenced by the mechanics of the ground-machine interactions. A rolling wheel in terrain with obstacles is subject to collisional energy losses, which is governed by mechanics comparable to hopping or walking locomotion. Here we investigate the energetic cost associated with overcoming an obstacle for rolling and hopping locomotion, using a simple mechanics model. The model considers collision-based interactions with the ground and the obstacle, without frictional losses, and we quantify, analyse, and compare the sources of energetic costs for three locomotion strategies. Our results show that the energetic advantages of the locomotion strategies are uniquely defined given the moment of inertia and the Froude number associated with the system. We find that hopping outperforms rolling at larger Froude numbers and vice versa. The analysis is further extended for a comparative study with animals. By applying size and inertial properties through an allometric scaling law of hopping and trotting animals to our models, we found that the conditions at which hopping becomes energetically advantageous to rolling roughly corresponds to animals’ preferred gait transition speeds. The energetic collision losses as predicted by the model are largely verified experimentally. PMID:29538459

  11. Multi-AUV Target Search Based on Bioinspired Neurodynamics Model in 3-D Underwater Environments.

    PubMed

    Cao, Xiang; Zhu, Daqi; Yang, Simon X

    2016-11-01

    Target search in 3-D underwater environments is a challenge in multiple autonomous underwater vehicles (multi-AUVs) exploration. This paper focuses on an effective strategy for multi-AUV target search in the 3-D underwater environments with obstacles. First, the Dempster-Shafer theory of evidence is applied to extract information of environment from the sonar data to build a grid map of the underwater environments. Second, a topologically organized bioinspired neurodynamics model based on the grid map is constructed to represent the dynamic environment. The target globally attracts the AUVs through the dynamic neural activity landscape of the model, while the obstacles locally push the AUVs away to avoid collision. Finally, the AUVs plan their search path to the targets autonomously by a steepest gradient descent rule. The proposed algorithm deals with various situations, such as static targets search, dynamic targets search, and one or several AUVs break down in the 3-D underwater environments with obstacles. The simulation results show that the proposed algorithm is capable of guiding multi-AUV to achieve search task of multiple targets with higher efficiency and adaptability compared with other algorithms.

  12. Effect of form of obstacle on speed of crowd evacuation

    NASA Astrophysics Data System (ADS)

    Yano, Ryosuke

    2018-03-01

    This paper investigates the effect of the form of an obstacle on the time that a crowd takes to evacuate a room, using a toy model. Pedestrians are modeled as active soft matter moving toward a point with intended velocities. An obstacle is placed in front of the exit, and it has one of four shapes: a cylindrical column, a triangular prism, a quadratic prism, or a diamond prism. Numerical results indicate that the evacuation-completion time depends on the shape of the obstacle. Obstacles with a circular cylinder (C.C.) shape yield the shortest evacuation-completion time in the proposed model.

  13. Identification of agents effective against multiple toxins and viruses by host-oriented cell targeting.

    PubMed

    Zilbermintz, Leeor; Leonardi, William; Jeong, Sun-Young; Sjodt, Megan; McComb, Ryan; Ho, Chi-Lee C; Retterer, Cary; Gharaibeh, Dima; Zamani, Rouzbeh; Soloveva, Veronica; Bavari, Sina; Levitin, Anastasia; West, Joel; Bradley, Kenneth A; Clubb, Robert T; Cohen, Stanley N; Gupta, Vivek; Martchenko, Mikhail

    2015-08-27

    A longstanding and still-increasing threat to the effective treatment of infectious diseases is resistance to antimicrobial countermeasures. Potentially, the targeting of host proteins and pathways essential for the detrimental effects of pathogens offers an approach that may discover broad-spectrum anti-pathogen countermeasures and circumvent the effects of pathogen mutations leading to resistance. Here we report implementation of a strategy for discovering broad-spectrum host-oriented therapies against multiple pathogenic agents by multiplex screening of drugs for protection against the detrimental effects of multiple pathogens, identification of host cell pathways inhibited by the drug, and screening for effects of the agent on other pathogens exploiting the same pathway. We show that a clinically used antimalarial drug, Amodiaquine, discovered by this strategy, protects host cells against infection by multiple toxins and viruses by inhibiting host cathepsin B. Our results reveal the practicality of discovering broadly acting anti-pathogen countermeasures that target host proteins exploited by pathogens.

  14. Methodology for object-oriented real-time systems analysis and design: Software engineering

    NASA Technical Reports Server (NTRS)

    Schoeffler, James D.

    1991-01-01

    Successful application of software engineering methodologies requires an integrated analysis and design life-cycle in which the various phases flow smoothly 'seamlessly' from analysis through design to implementation. Furthermore, different analysis methodologies often lead to different structuring of the system so that the transition from analysis to design may be awkward depending on the design methodology to be used. This is especially important when object-oriented programming is to be used for implementation when the original specification and perhaps high-level design is non-object oriented. Two approaches to real-time systems analysis which can lead to an object-oriented design are contrasted: (1) modeling the system using structured analysis with real-time extensions which emphasizes data and control flows followed by the abstraction of objects where the operations or methods of the objects correspond to processes in the data flow diagrams and then design in terms of these objects; and (2) modeling the system from the beginning as a set of naturally occurring concurrent entities (objects) each having its own time-behavior defined by a set of states and state-transition rules and seamlessly transforming the analysis models into high-level design models. A new concept of a 'real-time systems-analysis object' is introduced and becomes the basic building block of a series of seamlessly-connected models which progress from the object-oriented real-time systems analysis and design system analysis logical models through the physical architectural models and the high-level design stages. The methodology is appropriate to the overall specification including hardware and software modules. In software modules, the systems analysis objects are transformed into software objects.

  15. Application of Feature-Oriented Domain Analysis to the Army Movement Control Domain (Appendices A-I)

    DTIC Science & Technology

    1992-06-01

    Cohen, James A. Hess, William E. Novak, & A. Spen- cer Peterson. Feature-Oriented Domain Analysis ( FODA ) Feasibility Study (CMU/SEI-90- TR-21...Oriented Domain Analysis to the Army Movement Control Domain (Appendices A -1) Sholom G. Cohen Jay L. Stanley, Jr. A. Spencer Peterson Robert W...Appendices) June 1992 Application of Feature-Oriented Domain Analysis to the Army Movement Control Domain (Appendices A -1) Sholom G. Cohen Jay L

  16. An Analysis of Spanish L2 Learners' Orientation through Activity Theory

    ERIC Educational Resources Information Center

    Tocaimaza-Hatch, C. Cecilia

    2015-01-01

    Orientation is defined as the way in which individuals view a task and the means they devise to fulfill it (Appel & Lantolf, 1994; Roebuck, 2000). This study investigated the orientation of twelve learners enrolled in a fourth-semester Spanish L2 university course through the analysis of their interactions during a collaborative…

  17. Analysis of self-determined motivation in basketball players through goal orientations.

    PubMed

    Gómez-López, Manuel; Granero-Gallegos, Antonio; Abraldes, J Arturo; Rodríguez-Suárez, Nuria

    2013-09-01

    The purpose of this study was twofold. Firstly to examine the relations between the different constructs that defines Nicholls' Achievement Goal Theory and Deci and Ryan's self-determination theory. Secondly to analyse the differences that exist between them with respect to the socio-demographic variables gender and age. A sample of 292 federated basketball players from the Region of Murcia (Spain) with ages between 14 and 18 years old was used. In addition, Castilian versions of The Perception of Success Questionnaire (POSQ) and the Sports Motivational Scale (SMS) were administered. Three statistical analyses were employed, a descriptive analysis, a correlation analysis and a regression analysis. The results showed a positive relation between ego orientation, extrinsic motivation and amotivation. The motivational relations between both theories and the differences with respect to gender and age are discussed. We have found out that mainly gender and also age differences are strong predictors of ego orientation, extrinsic motivation of external regulation and amotivation. We can also confirm that extrinsic motivation of external regulation positively predicts ego orientation and a decrease of task orientation. The results ratify the use of the Spanish version of the SMS to measure different types of motivation within the sports context.

  18. Obstacle Detection using Binocular Stereo Vision in Trajectory Planning for Quadcopter Navigation

    NASA Astrophysics Data System (ADS)

    Bugayong, Albert; Ramos, Manuel, Jr.

    2018-02-01

    Quadcopters are one of the most versatile unmanned aerial vehicles due to its vertical take-off and landing as well as hovering capabilities. This research uses the Sum of Absolute Differences (SAD) block matching algorithm for stereo vision. A complementary filter was used in sensor fusion to combine obtained quadcopter orientation data from the accelerometer and the gyroscope. PID control was implemented for the motor control and VFH+ algorithm was implemented for trajectory planning. Results show that the quadcopter was able to consistently actuate itself in the roll, yaw and z-axis during obstacle avoidance but was however found to be inconsistent in the pitch axis during forward and backward maneuvers due to the significant noise present in the pitch axis angle outputs compared to the roll and yaw axes.

  19. “Combination-oriented molecular-targeting prevention” of cancer: a model involving the combination of TRAIL and a DR5 inducer

    PubMed Central

    Yoshida, Tatsushi; Horinaka, Mano

    2010-01-01

    Malignant tumors carry a high risk of death, and the prevention of malignant tumors is a crucial issue in preventive medicine. To this end, many chemopreventive agents have been tested, but the effects of single agents have been found to be insufficient to justify clinical trials. We have therefore hypothesized that combinations of different chemopreventive agents may synergistically enhance the preventive effect of chemopreventive agents used singly. To provide the treating physician with some guideline by which to choose the most effective agents to be combined, we propose a strategy which we have termed the “combination-oriented molecular-targeting prevention” of cancer. As the molecular target of our model, we focused on tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), which specifically causes apoptosis in malignant tumor cells. Many of these agents were found to up-regulate the expression of death receptor 5, a TRAIL receptor. They were also found to synergistically induce apoptosis in malignant tumor cells when combined with TRAIL. Here, we strongly advocate that the strategy of “combination-oriented molecular-targeting prevention” of cancer will be a practical approach for chemoprevention against human malignant tumors. PMID:21432546

  20. Laser development for optimal helicopter obstacle warning system LADAR performance

    NASA Astrophysics Data System (ADS)

    Yaniv, A.; Krupkin, V.; Abitbol, A.; Stern, J.; Lurie, E.; German, A.; Solomonovich, S.; Lubashitz, B.; Harel, Y.; Engart, S.; Shimoni, Y.; Hezy, S.; Biltz, S.; Kaminetsky, E.; Goldberg, A.; Chocron, J.; Zuntz, N.; Zajdman, A.

    2005-04-01

    Low lying obstacles present immediate danger to both military and civilian helicopters performing low-altitude flight missions. A LADAR obstacle detection system is the natural solution for enhancing helicopter safety and improving the pilot situation awareness. Elop is currently developing an advanced Surveillance and Warning Obstacle Ranging and Display (SWORD) system for the Israeli Air Force. Several key factors and new concepts have contributed to system optimization. These include an adaptive FOV, data memorization, autonomous obstacle detection and warning algorithms and the use of an agile laser transmitter. In the present work we describe the laser design and performance and discuss some of the experimental results. Our eye-safe laser is characterized by its pulse energy, repetition rate and pulse length agility. By dynamically controlling these parameters, we are able to locally optimize the system"s obstacle detection range and scan density in accordance with the helicopter instantaneous maneuver.

  1. Influence of obstacles on bubbles rising in water-saturated sand

    NASA Astrophysics Data System (ADS)

    Poryles, Raphaël; Varas, Germán; Vidal, Valérie

    2017-06-01

    This work investigates the dynamics of air rising through a water-saturated sand confined in a Hele- Shaw cell in which a circular obstacle is trapped. The air is injected at constant flow rate through a single nozzle at the bottom center of the cell. Without obstacle, in a similar configuration, previous studies pointed out the existence of a fluidized zone generated by the central upward gas motion which entrains two granular convection rolls on its sides. Here, a circular obstacle which diameter is of the order of the central air channel width is trapped at the vertical of the injection nozzle. We analyze the influence of the obstacle location on the size of the fluidized zone and its impact on the morphology of the central air channel. Finally, we quantify the variations of the granular free surface. Two configurations with multiple obstacles are also considered.

  2. User-oriented summary extraction for soccer video based on multimodal analysis

    NASA Astrophysics Data System (ADS)

    Liu, Huayong; Jiang, Shanshan; He, Tingting

    2011-11-01

    An advanced user-oriented summary extraction method for soccer video is proposed in this work. Firstly, an algorithm of user-oriented summary extraction for soccer video is introduced. A novel approach that integrates multimodal analysis, such as extraction and analysis of the stadium features, moving object features, audio features and text features is introduced. By these features the semantic of the soccer video and the highlight mode are obtained. Then we can find the highlight position and put them together by highlight degrees to obtain the video summary. The experimental results for sports video of world cup soccer games indicate that multimodal analysis is effective for soccer video browsing and retrieval.

  3. Novel approaches to helicopter obstacle warning

    NASA Astrophysics Data System (ADS)

    Seidel, Christian; Samuelis, Christian; Wegner, Matthias; Münsterer, Thomas; Rumpf, Thomas; Schwartz, Ingo

    2006-05-01

    EADS Germany is the world market leader in commercial Helicopter Laser Radar (HELLAS) Obstacle Warning Systems. The HELLAS-Warning System has been introduced into the market in 2000, is in service at German Border Control (Bundespolizei) and Royal Thai Airforce and is successfully evaluated by the Foreign Comparative Test Program (FCT) of the USSOCOM. Currently the successor system HELLAS-Awareness is in development. It will have extended sensor performance, enhanced realtime data processing capabilities and advanced HMI features. We will give an outline of the new sensor unit concerning detection technology and helicopter integration aspects. The system provides a widespread field of view with additional dynamic line of sight steering and a large detection range in combination with a high frame rate of 3Hz. The workflow of the data processing will be presented with focus on novel filter techniques and obstacle classification methods. As commonly known the former are indispensable due to unavoidable statistical measuring errors and solarisation. The amount of information in the filtered raw data is further reduced by ground segmentation. The remaining raised objects are extracted and classified in several stages into different obstacle classes. We will show the prioritization function which orders the obstacles concerning to their threat potential to the helicopter taking into account the actual flight dynamics. The priority of an object determines the display and provision of warnings to the pilot. Possible HMI representation includes video or FLIR overlay on multifunction displays, audio warnings and visualization of information on helmet mounted displays and digital maps. Different concepts will be presented.

  4. Improved Sectional Image Analysis Technique for Evaluating Fiber Orientations in Fiber-Reinforced Cement-Based Materials.

    PubMed

    Lee, Bang Yeon; Kang, Su-Tae; Yun, Hae-Bum; Kim, Yun Yong

    2016-01-12

    The distribution of fiber orientation is an important factor in determining the mechanical properties of fiber-reinforced concrete. This study proposes a new image analysis technique for improving the evaluation accuracy of fiber orientation distribution in the sectional image of fiber-reinforced concrete. A series of tests on the accuracy of fiber detection and the estimation performance of fiber orientation was performed on artificial fiber images to assess the validity of the proposed technique. The validation test results showed that the proposed technique estimates the distribution of fiber orientation more accurately than the direct measurement of fiber orientation by image analysis.

  5. Improved Sectional Image Analysis Technique for Evaluating Fiber Orientations in Fiber-Reinforced Cement-Based Materials

    PubMed Central

    Lee, Bang Yeon; Kang, Su-Tae; Yun, Hae-Bum; Kim, Yun Yong

    2016-01-01

    The distribution of fiber orientation is an important factor in determining the mechanical properties of fiber-reinforced concrete. This study proposes a new image analysis technique for improving the evaluation accuracy of fiber orientation distribution in the sectional image of fiber-reinforced concrete. A series of tests on the accuracy of fiber detection and the estimation performance of fiber orientation was performed on artificial fiber images to assess the validity of the proposed technique. The validation test results showed that the proposed technique estimates the distribution of fiber orientation more accurately than the direct measurement of fiber orientation by image analysis. PMID:28787839

  6. Facet orientation in the thoracolumbar spine: three-dimensional anatomic and biomechanical analysis.

    PubMed

    Masharawi, Youssef; Rothschild, Bruce; Dar, Gali; Peleg, Smadar; Robinson, Dror; Been, Ella; Hershkovitz, Israel

    2004-08-15

    Thoracolumbar facet orientations were measured and analyzed. To establish a comprehensive database for facet orientation in the thoracolumbar vertebrae and to determine the normal human condition. Most studies on facet orientation have based their conclusions on two-dimensional measurements, in small samples or isolated vertebrae. The amount of normal asymmetry in facet orientation is poorly addressed. Transverse and longitudinal facet angles were measured directly from 240 human vertebral columns (males/females, blacks/whites). The specimens' osteologic material is part of the Hamann-Todd Osteological Collection housed at the Cleveland Museum of Natural History (Cleveland, OH). A total of 4,080 vertebrae (T1-L5) from the vertebral columns of individuals 20 to 80 years of age were measured, using a Microscribe three-dimensional apparatus (Immersion Co., San Jose, CA). Data were recorded directly on computer software. Statistical analysis included paired t tests and analysis of variance. RESULTS.: Facet orientation is independent of gender, age, and ethnic group. Asymmetry in facet orientation is found in the thorax. All thoracolumbar facets are positioned in an oblique plane. In the transverse plane, all facets from T1 to T11 are positioned with an anterior inclination of approximately 25 degrees to 30 degrees from the frontal plane. The facets of T12-L2 are oriented closer to the midsagittal plane of the vertebral body (mean range, 25.89 degrees-33.87 degrees), while the facets of L3-L5 are oriented away from that plane (mean range, 40.40 degrees-56.30 degrees). Facet transverse orientation at the thoracolumbar junction is highly variable (approximately 80% with approximately 101 degrees and approximately 20% with 35 degrees). All facets are oriented more vertically from T1 (approximately 150 degrees) to L5 (approximately 170 degrees). The facet sagittal orientations of the lumbar zygoapophyseal joints are not equivalent. CONCLUSIONS.: Asymmetry in facet

  7. Performance and three-dimensional kinematics of bipedal lizards during obstacle negotiation.

    PubMed

    Olberding, Jeffrey P; McBrayer, Lance D; Higham, Timothy E

    2012-01-15

    Bipedal running is common among lizard species, but although the kinematics and performance of this gait have been well characterized, the advantages in biologically relevant situations are still unclear. Obstacle negotiation is a task that is ecologically relevant to many animals while moving at high speeds, such as during bipedal running, yet little is known about how obstacles impact locomotion and performance. We examined the effects of obstacle negotiation on the kinematics and performance of lizards during bipedal locomotion. We quantified three-dimensional kinematics from high-speed video (500 Hz) of six-lined racerunners (Aspidoscelis sexlineata) running on a 3 m racetrack both with and without an obstacle spanning the width of the track. The lizards did not alter their kinematics prior to contacting the obstacle. Although contact with the obstacle caused changes to the hindlimb kinematics, mean forward speed did not differ between treatments. The deviation of the vertical position of the body center of mass did not differ between treatments, suggesting that in the absence of a cost to overall performance, lizards forgo maintaining normal kinematics while negotiating obstacles in favor of a steady body center of mass height to avoid destabilizing locomotion.

  8. Advanced Augmented White Cane with obstacle height and distance feedback.

    PubMed

    Pyun, Rosali; Kim, Yeongmi; Wespe, Pascal; Gassert, Roger; Schneller, Stefan

    2013-06-01

    The white cane is a widely used mobility aid that helps visually impaired people navigate the surroundings. While it reliably and intuitively extends the detection range of ground-level obstacles and drop-offs to about 1.2 m, it lacks the ability to detect trunk and head-level obstacles. Electronic Travel Aids (ETAs) have been proposed to overcome these limitations, but have found minimal adoption due to limitations such as low information content and low reliability thereof. Although existing ETAs extend the sensing range beyond that of the conventional white cane, most of them do not detect head-level obstacles and drop-offs, nor can they identify the vertical extent of obstacles. Furthermore, some ETAs work independent of the white cane, and thus reliable detection of surface textures and drop-offs is not provided. This paper introduces a novel ETA, the Advanced Augmented White Cane, which detects obstacles at four vertical levels and provides multi-sensory feedback. We evaluated the device in five blindfolded subjects through reaction time measurements following the detection of an obstacle, as well as through the reliability of dropoff detection. The results showed that our aid could help the user successfully detect an obstacle and identify its height, with an average reaction time of 410 msec. Drop-offs were reliably detected with an intraclass correlation > 0.95. This work is a first step towards a low-cost ETA to complement the functionality of the conventional white cane.

  9. How Obstacles Perturb Population Fronts and Alter Their Genetic Structure

    PubMed Central

    Möbius, Wolfram; Murray, Andrew W.; Nelson, David R.

    2015-01-01

    As populations spread into new territory, environmental heterogeneities can shape the population front and genetic composition. We focus here on the effects of an important building block of heterogeneous environments, isolated obstacles. With a combination of experiments, theory, and simulation, we show how isolated obstacles both create long-lived distortions of the front shape and amplify the effect of genetic drift. A system of bacteriophage T7 spreading on a spatially heterogeneous Escherichia coli lawn serves as an experimental model system to study population expansions. Using an inkjet printer, we create well-defined replicates of the lawn and quantitatively study the population expansion of phage T7. The transient perturbations of the population front found in the experiments are well described by a model in which the front moves with constant speed. Independent of the precise details of the expansion, we show that obstacles create a kink in the front that persists over large distances and is insensitive to the details of the obstacle’s shape. The small deviations between experimental findings and the predictions of the constant speed model can be understood with a more general reaction-diffusion model, which reduces to the constant speed model when the obstacle size is large compared to the front width. Using this framework, we demonstrate that frontier genotypes just grazing the side of an isolated obstacle increase in abundance, a phenomenon we call ‘geometry-enhanced genetic drift’, complementary to the founder effect associated with spatial bottlenecks. Bacterial range expansions around nutrient-poor barriers and stochastic simulations confirm this prediction. The effect of the obstacle on the genealogy of individuals at the front is characterized by simulations and rationalized using the constant speed model. Lastly, we consider the effect of two obstacles on front shape and genetic composition of the population illuminating the effects

  10. Sensorimotor Model of Obstacle Avoidance in Echolocating Bats

    PubMed Central

    Vanderelst, Dieter; Holderied, Marc W.; Peremans, Herbert

    2015-01-01

    Bat echolocation is an ability consisting of many subtasks such as navigation, prey detection and object recognition. Understanding the echolocation capabilities of bats comes down to isolating the minimal set of acoustic cues needed to complete each task. For some tasks, the minimal cues have already been identified. However, while a number of possible cues have been suggested, little is known about the minimal cues supporting obstacle avoidance in echolocating bats. In this paper, we propose that the Interaural Intensity Difference (IID) and travel time of the first millisecond of the echo train are sufficient cues for obstacle avoidance. We describe a simple control algorithm based on the use of these cues in combination with alternating ear positions modeled after the constant frequency bat Rhinolophus rouxii. Using spatial simulations (2D and 3D), we show that simple phonotaxis can steer a bat clear from obstacles without performing a reconstruction of the 3D layout of the scene. As such, this paper presents the first computationally explicit explanation for obstacle avoidance validated in complex simulated environments. Based on additional simulations modelling the FM bat Phyllostomus discolor, we conjecture that the proposed cues can be exploited by constant frequency (CF) bats and frequency modulated (FM) bats alike. We hypothesize that using a low level yet robust cue for obstacle avoidance allows bats to comply with the hard real-time constraints of this basic behaviour. PMID:26502063

  11. Stepping over obstacles: anticipatory modifications in children with and without Down syndrome.

    PubMed

    Virji-Babul, Naznin; Brown, Michelle

    2004-12-01

    The purpose of this study was to explore the mechanism of anticipatory control of gait in relation to the perception of an obstacle. Typically developing (TD) children (4-7 years of age) and children with Down syndrome (5-6 years of age) walked and stepped over obstacles of two different heights-a "subtle" obstacle that was placed at a very low distance from the floor (1% of total body height) and an "obvious" obstacle that was placed at a much higher distance from the floor (15% of total body height). Spatial and temporal measures of the gait cycle were analyzed. TD children showed increased variability in pre-obstacle step lengths only in response to the higher obstacle. Children with DS showed a decrease in variability in response to the higher obstacle and marked qualitative changes in their gait cycle. Both groups of children were able to scale toe clearance with obstacle height. These results show that TD young children can make task-specific anticipatory adjustments by modulating step length and toe clearance. Children with DS show appropriate scaling of toe clearance and are beginning to show the emergence of anticipatory responses under specific environmental conditions.

  12. Detection of obstacles on runway using Ego-Motion compensation and tracking of significant features

    NASA Technical Reports Server (NTRS)

    Kasturi, Rangachar (Principal Investigator); Camps, Octavia (Principal Investigator); Gandhi, Tarak; Devadiga, Sadashiva

    1996-01-01

    This report describes a method for obstacle detection on a runway for autonomous navigation and landing of an aircraft. Detection is done in the presence of extraneous features such as tiremarks. Suitable features are extracted from the image and warping using approximately known camera and plane parameters is performed in order to compensate ego-motion as far as possible. Residual disparity after warping is estimated using an optical flow algorithm. Features are tracked from frame to frame so as to obtain more reliable estimates of their motion. Corrections are made to motion parameters with the residual disparities using a robust method, and features having large residual disparities are signaled as obstacles. Sensitivity analysis of the procedure is also studied. Nelson's optical flow constraint is proposed to separate moving obstacles from stationary ones. A Bayesian framework is used at every stage so that the confidence in the estimates can be determined.

  13. Position and orientation tracking system

    DOEpatents

    Burks, Barry L.; DePiero, Fred W.; Armstrong, Gary A.; Jansen, John F.; Muller, Richard C.; Gee, Timothy F.

    1998-01-01

    A position and orientation tracking system presents a laser scanning appaus having two measurement pods, a control station, and a detector array. The measurement pods can be mounted in the dome of a radioactive waste storage silo. Each measurement pod includes dual orthogonal laser scanner subsystems. The first laser scanner subsystem is oriented to emit a first line laser in the pan direction. The second laser scanner is oriented to emit a second line laser in the tilt direction. Both emitted line lasers scan planes across the radioactive waste surface to encounter the detector array mounted on a target robotic vehicle. The angles of incidence of the planes with the detector array are recorded by the control station. Combining measurements describing each of the four planes provides data for a closed form solution of the algebraic transform describing the position and orientation of the target robotic vehicle.

  14. Position and orientation tracking system

    DOEpatents

    Burks, B.L.; DePiero, F.W.; Armstrong, G.A.; Jansen, J.F.; Muller, R.C.; Gee, T.F.

    1998-05-05

    A position and orientation tracking system presents a laser scanning apparatus having two measurement pods, a control station, and a detector array. The measurement pods can be mounted in the dome of a radioactive waste storage silo. Each measurement pod includes dual orthogonal laser scanner subsystems. The first laser scanner subsystem is oriented to emit a first line laser in the pan direction. The second laser scanner is oriented to emit a second line laser in the tilt direction. Both emitted line lasers scan planes across the radioactive waste surface to encounter the detector array mounted on a target robotic vehicle. The angles of incidence of the planes with the detector array are recorded by the control station. Combining measurements describing each of the four planes provides data for a closed form solution of the algebraic transform describing the position and orientation of the target robotic vehicle. 14 figs.

  15. Evaluation of Learning Environments for Object-Oriented Programming: Measuring Cognitive Load with a Novel Measurement Technique

    ERIC Educational Resources Information Center

    Uysal, Murat Pasa

    2016-01-01

    Various methods and tools have been proposed to overcome the learning obstacles for Object-Oriented Programming (OOP). However, it remains difficult especially for novice learners. The problem may be not only adopting an instructional method, but also an Integrated Development Environment (IDE). Learners employ IDEs as a means to solve programming…

  16. A Monocular Vision Sensor-Based Obstacle Detection Algorithm for Autonomous Robots.

    PubMed

    Lee, Tae-Jae; Yi, Dong-Hoon; Cho, Dong-Il Dan

    2016-03-01

    This paper presents a monocular vision sensor-based obstacle detection algorithm for autonomous robots. Each individual image pixel at the bottom region of interest is labeled as belonging either to an obstacle or the floor. While conventional methods depend on point tracking for geometric cues for obstacle detection, the proposed algorithm uses the inverse perspective mapping (IPM) method. This method is much more advantageous when the camera is not high off the floor, which makes point tracking near the floor difficult. Markov random field-based obstacle segmentation is then performed using the IPM results and a floor appearance model. Next, the shortest distance between the robot and the obstacle is calculated. The algorithm is tested by applying it to 70 datasets, 20 of which include nonobstacle images where considerable changes in floor appearance occur. The obstacle segmentation accuracies and the distance estimation error are quantitatively analyzed. For obstacle datasets, the segmentation precision and the average distance estimation error of the proposed method are 81.4% and 1.6 cm, respectively, whereas those for a conventional method are 57.5% and 9.9 cm, respectively. For nonobstacle datasets, the proposed method gives 0.0% false positive rates, while the conventional method gives 17.6%.

  17. A Monocular Vision Sensor-Based Obstacle Detection Algorithm for Autonomous Robots

    PubMed Central

    Lee, Tae-Jae; Yi, Dong-Hoon; Cho, Dong-Il “Dan”

    2016-01-01

    This paper presents a monocular vision sensor-based obstacle detection algorithm for autonomous robots. Each individual image pixel at the bottom region of interest is labeled as belonging either to an obstacle or the floor. While conventional methods depend on point tracking for geometric cues for obstacle detection, the proposed algorithm uses the inverse perspective mapping (IPM) method. This method is much more advantageous when the camera is not high off the floor, which makes point tracking near the floor difficult. Markov random field-based obstacle segmentation is then performed using the IPM results and a floor appearance model. Next, the shortest distance between the robot and the obstacle is calculated. The algorithm is tested by applying it to 70 datasets, 20 of which include nonobstacle images where considerable changes in floor appearance occur. The obstacle segmentation accuracies and the distance estimation error are quantitatively analyzed. For obstacle datasets, the segmentation precision and the average distance estimation error of the proposed method are 81.4% and 1.6 cm, respectively, whereas those for a conventional method are 57.5% and 9.9 cm, respectively. For nonobstacle datasets, the proposed method gives 0.0% false positive rates, while the conventional method gives 17.6%. PMID:26938540

  18. Clogging and jamming transitions in periodic obstacle arrays

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

    Nguyen, Hong; Reichhardt, Charles; Olson Reichhardt, Cynthia Jane

    2017-03-29

    We numerically examine clogging transitions for bidisperse disks flowing through a two-dimensional periodic obstacle array. Here, we show that clogging is a probabilistic event that occurs through a transition from a homogeneous flowing state to a heterogeneous or phase-separated jammed state where the disks form dense connected clusters. The probability for clogging to occur during a fixed time increases with increasing particle packing and obstacle number. For driving at different angles with respect to the symmetry direction of the obstacle array, we show that certain directions have a higher clogging susceptibility. It is also possible to have a size-specific cloggingmore » transition in which one disk size becomes completely immobile while the other disk size continues to flow.« less

  19. Obstacle detection and avoiding of quadcopter

    NASA Astrophysics Data System (ADS)

    Wang, Dizhong; Lin, Jiajian

    2017-10-01

    Recent years, the flight control technology over quadcopter has been boosted vigorously and acquired the comprehensive application in a variety of industries. However, it is prominent for there to be problems existed in the stable and secure flight with the development of its autonomous flight. Through comparing with the characteristics of ultrasonic ranging and laser Time-of-Flight(abbreviated to ToF) distance as well as vision measurement and its related sensors, the obstacle detection and identification sensors need to be installed in order to effectively enhance the safety flying for aircraft, which is essential for avoiding the dangers around the surroundings. That the major sensors applied to objects perception at present are distance measuring instruments which based on the principle and application of non-contact detection technology . Prior to acknowledging the general principles of flight and obstacle avoiding, the aerodynamics modeling of the quadcopter and its object detection means has been initially determined on this paper. Based on such premise, this article emphasized on describing and analyzing the research on obstacle avoiding technology and its application status, and making an expectation for the trend of its development after analyzing the primary existing problems concerning its accuracy object avoidance.

  20. Safe Maritime Navigation with COLREGS Using Velocity Obstacles

    NASA Technical Reports Server (NTRS)

    Kuwata, Yoshiaki; Wolf, Michael T.; Zarzhitsky, Dimitri; Huntsberger, Terrance L.

    2011-01-01

    This paper presents a motion planning algorithm for Unmanned Surface Vehicles (USVs) to navigate safely in dynamic, cluttered environments. The proposed algorithm not only addresses Hazard Avoidance (HA) for stationary and moving hazards but also applies the International Regulations for Preventing Collisions at Sea (known as COLREGs). The COLREG rules specify, for example, which vessel is responsible for giving way to the other and to which side of the "stand-on" vessel to maneuver. The three primary COLREG rules were considered in this paper: crossing, overtaking, and head-on situations. For USVs to be safely deployed in environments with other traffic boats, it is imperative that the USV's navigation algorithm obey COLREGs. Note also that if other boats disregard their responsibility under COLREGs, the USV will still apply its HA algorithms to avoid a collision. The proposed approach is based on Velocity Obstacles, which generates a cone-shaped obstacle in the velocity space. Because Velocity Obstacles also specify which side of the obstacle the vehicle will pass during the avoidance maneuver, COLREGs are encoded in the velocity space in a natural way. The algorithm is demonstrated via both simulation and on-water tests.

  1. The effects of multiple obstacles on the locomotor behavior and performance of a terrestrial lizard.

    PubMed

    Parker, Seth E; McBrayer, Lance D

    2016-04-01

    Negotiation of variable terrain is important for many small terrestrial vertebrates. Variation in the running surface resulting from obstacles (woody debris, vegetation, rocks) can alter escape paths and running performance. The ability to navigate obstacles likely influences survivorship through predator evasion success and other key ecological tasks (finding mates, acquiring food). Earlier work established that running posture and sprint performance are altered when organisms face an obstacle, and yet studies involving multiple obstacles are limited. Indeed, some habitats are cluttered with obstacles, whereas others are not. For many species, obstacle density may be important in predator escape and/or colonization potential by conspecifics. This study examines how multiple obstacles influence running behavior and locomotor posture in lizards. We predict that an increasing number of obstacles will increase the frequency of pausing and decrease sprint velocity. Furthermore, bipedal running over multiple obstacles is predicted to maintain greater mean sprint velocity compared with quadrupedal running, thereby revealing a potential advantage of bipedalism. Lizards were filmed running through a racetrack with zero, one or two obstacles. Bipedal running posture over one obstacle was significantly faster than quadrupedal posture. Bipedal running trials contained fewer total strides than quadrupedal ones. But on addition of a second obstacle, the number of bipedal strides decreased. Increasing obstacle number led to slower and more intermittent locomotion. Bipedalism provided clear advantages for one obstacle, but was not associated with further benefits for an additional obstacle. Hence, bipedalism helps mitigate obstacle negotiation, but not when numerous obstacles are encountered in succession. © 2016. Published by The Company of Biologists Ltd.

  2. Stochastic performance modeling and evaluation of obstacle detectability with imaging range sensors

    NASA Technical Reports Server (NTRS)

    Matthies, Larry; Grandjean, Pierrick

    1993-01-01

    Statistical modeling and evaluation of the performance of obstacle detection systems for Unmanned Ground Vehicles (UGVs) is essential for the design, evaluation, and comparison of sensor systems. In this report, we address this issue for imaging range sensors by dividing the evaluation problem into two levels: quality of the range data itself and quality of the obstacle detection algorithms applied to the range data. We review existing models of the quality of range data from stereo vision and AM-CW LADAR, then use these to derive a new model for the quality of a simple obstacle detection algorithm. This model predicts the probability of detecting obstacles and the probability of false alarms, as a function of the size and distance of the obstacle, the resolution of the sensor, and the level of noise in the range data. We evaluate these models experimentally using range data from stereo image pairs of a gravel road with known obstacles at several distances. The results show that the approach is a promising tool for predicting and evaluating the performance of obstacle detection with imaging range sensors.

  3. Obstacle evasion in free-space optical communications utilizing Airy beams.

    PubMed

    Zhu, Guoxuan; Wen, Yuanhui; Wu, Xiong; Chen, Yujie; Liu, Jie; Yu, Siyuan

    2018-03-15

    A high speed free-space optical communication system capable of self-bending signal transmission around line-of-sight obstacles is proposed and demonstrated. Airy beams are generated and controlled to achieve different propagating trajectories, and the signal transmission characteristics of these beams around the obstacle are investigated. Our results confirm that, by optimizing their ballistic trajectories, Airy beams are able to bypass obstacles with more signal energy and thus improve the communication performance compared with normal Gaussian beams.

  4. Obstacle evasion in free-space optical communications utilizing Airy beams

    NASA Astrophysics Data System (ADS)

    Zhu, Guoxuan; Wen, Yuanhui; Wu, Xiong; Chen, Yujie; Liu, Jie; Yu, Siyuan

    2018-03-01

    A high speed free-space optical communication system capable of self-bending signal transmission around line-of-sight obstacles is proposed and demonstrated. Airy beams are generated and controlled to achieve different propagating trajectories, and the signal transmission characteristics of these beams around the obstacle are investigated. Our results confirm that, by optimising their ballistic trajectories, Airy beams are able to bypass obstacles with more signal energy and thus improve the communication performance compared with normal Gaussian beams.

  5. Shifting forest value orientations in the United States, 1980-2001: A computer content analysis

    Treesearch

    David N. Bengston; Trevor J. Webb; David P. Fan

    2004-01-01

    This paper examines three forest value orientations - clusters of interrelated values and basic beliefs about forests - that emerged from an analysis of the public discourse about forest planning, management, and policy in the United States. The value orientations include anthropocentric, biocentric, and moral/spiritual/aesthetic orientations toward forests. Computer...

  6. Propagation of spiral waves pinned to circular and rectangular obstacles.

    PubMed

    Sutthiopad, Malee; Luengviriya, Jiraporn; Porjai, Porramain; Phantu, Metinee; Kanchanawarin, Jarin; Müller, Stefan C; Luengviriya, Chaiya

    2015-05-01

    We present an investigation of spiral waves pinned to circular and rectangular obstacles with different circumferences in both thin layers of the Belousov-Zhabotinsky reaction and numerical simulations with the Oregonator model. For circular objects, the area always increases with the circumference. In contrast, we varied the circumference of rectangles with equal areas by adjusting their width w and height h. For both obstacle forms, the propagating parameters (i.e., wavelength, wave period, and velocity of pinned spiral waves) increase with the circumference, regardless of the obstacle area. Despite these common features of the parameters, the forms of pinned spiral waves depend on the obstacle shapes. The structures of spiral waves pinned to circles as well as rectangles with the ratio w/h∼1 are similar to Archimedean spirals. When w/h increases, deformations of the spiral shapes are observed. For extremely thin rectangles with w/h≫1, these shapes can be constructed by employing semicircles with different radii which relate to the obstacle width and the core diameter of free spirals.

  7. Oriented and covalent immobilization of target molecules to solid supports: synthesis and application of a light-activatable and thiol-reactive cross-linking reagent.

    PubMed

    Collioud, A; Clémence, J F; Sänger, M; Sigrist, H

    1993-01-01

    Light-dependent oriented and covalent immobilization of target molecules has been achieved by combining two modification procedures: light-dependent coupling of target molecules to inert surfaces and thiol-selective reactions occurring at macromolecule or substrate surfaces. For immobilization purposes the heterobifunctional reagent N-[m-[3-(trifluoromethyl)diazirin-3-yl]phenyl]-4-maleimidobutyr amide was synthesized and chemically characterized. The photosensitivity of the carbene-generating reagent and its reactivity toward thiols were ascertained. Light-induced cross-linking properties of the reagent were documented (i) by reacting first the maleimide function with a thiolated surface, followed by carbene insertion into applied target molecules, (ii) by photochemical coupling of the reagent to an inert support followed by thermochemical reactions with thiol functions, and (iii) by thermochemical modification of target molecules prior to carbene-mediated insertion into surface materials. Procedures mentioned led to light-dependent covalent immobilization of target molecules including amino acids, a synthetic peptide, and antibody-derived F(ab') fragments. Topically selective, light-dependent immobilization was attained with the bifunctional reagent by irradiation of coated surfaces through patterned masks. Glass and polystyrene served as substrates. Molecular orientation is asserted by inherently available or selectively introduced terminal thiol functions in F(ab') fragments and synthetic polypeptides, respectively.

  8. Virtual reality-based navigation task to reveal obstacle avoidance performance in individuals with visuospatial neglect.

    PubMed

    Aravind, Gayatri; Darekar, Anuja; Fung, Joyce; Lamontagne, Anouk

    2015-03-01

    Persons with post-stroke visuospatial neglect (VSN) often collide with moving obstacles while walking. It is not well understood whether the collisions occur as a result of attentional-perceptual deficits caused by VSN or due to post-stroke locomotor deficits. We assessed individuals with VSN on a seated, joystick-driven obstacle avoidance task, thus eliminating the influence of locomotion. Twelve participants with VSN were tested on obstacle detection and obstacle avoidance tasks in a virtual environment that included three obstacles approaching head-on or 30 (°) contralesionally/ipsilesionally. Our results indicate that in the detection task, the contralesional and head-on obstacles were detected at closer proximities compared to the ipsilesional obstacle. For the avoidance task collisions were observed only for the contralesional and head-on obstacle approaches. For the contralesional obstacle approach, participants initiated their avoidance strategies at smaller distances from the obstacle and maintained smaller minimum distances from the obstacles. The distance at detection showed a negative association with the distance at the onset of avoidance strategy for all three obstacle approaches. We conclusion the observation of collisions with contralesional and head-on obstacles, in the absence of locomotor burden, provides evidence that attentional-perceptual deficits due to VSN, independent of post-stroke locomotor deficits, alter obstacle avoidance abilities.

  9. Lossless and Sufficient - Invariant Decomposition of Deterministic Target

    NASA Astrophysics Data System (ADS)

    Paladini, Riccardo; Ferro Famil, Laurent; Pottier, Eric; Martorella, Marco; Berizzi, Fabrizio

    2011-03-01

    The symmetric radar scattering matrix of a reciprocal target is projected on the circular polarization basis and is decomposed into four orientation invariant parameters, relative phase and relative orientation. The physical interpretation of this results is found in the wave-particle nature of radar scattering due to the circular polarization nature of elemental packets of energy. The proposed decomposition, is based on left orthogonal to left Special Unitary basis, providing the target description in term of a unitary vector. A comparison between the proposed CTD and Cameron, Kennaugh and Krogager decompositions is also pointed out. A validation by the use of both anechoic chamber data and airborne EMISAR data of DTU is used to show the effectiveness of this decomposition for the analysis of coherent targets. In the second paper we will show the application of the rotation group U(3) for the decomposition of distributed targets into nine meaningful parameters.

  10. Recognition of an obstacle in a flow using artificial neural networks.

    PubMed

    Carrillo, Mauricio; Que, Ulices; González, José A; López, Carlos

    2017-08-01

    In this work a series of artificial neural networks (ANNs) has been developed with the capacity to estimate the size and location of an obstacle obstructing the flow in a pipe. The ANNs learn the size and location of the obstacle by reading the profiles of the dynamic pressure q or the x component of the velocity v_{x} of the fluid at a certain distance from the obstacle. Data to train the ANN were generated using numerical simulations with a two-dimensional lattice Boltzmann code. We analyzed various cases varying both the diameter and the position of the obstacle on the y axis, obtaining good estimations using the R^{2} coefficient for the cases under study. Although the ANN showed problems with the classification of very small obstacles, the general results show a very good capacity for prediction.

  11. Assessment of a simple obstacle detection device for the visually impaired.

    PubMed

    Lee, Cheng-Lung; Chen, Chih-Yung; Sung, Peng-Cheng; Lu, Shih-Yi

    2014-07-01

    A simple obstacle detection device, based upon an automobile parking sensor, was assessed as a mobility aid for the visually impaired. A questionnaire survey for mobility needs was performed at the start of this study. After the detector was developed, five blindfolded sighted and 15 visually impaired participants were invited to conduct travel experiments under three test conditions: (1) using a white cane only, (2) using the obstacle detector only and (3) using both devices. A post-experiment interview regarding the usefulness of the obstacle detector for the visually impaired participants was performed. The results showed that the obstacle detector could augment mobility performance with the white cane. The obstacle detection device should be used in conjunction with the white cane to achieve the best mobility speed and body protection. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  12. Distinct retinal pathways drive spatial orientation behaviors in zebrafish navigation.

    PubMed

    Burgess, Harold A; Schoch, Hannah; Granato, Michael

    2010-02-23

    Navigation requires animals to adjust ongoing movements in response to pertinent features of the environment and select between competing target cues. The neurobiological basis of navigational behavior in vertebrates is hard to analyze, partly because underlying neural circuits are experience dependent. Phototaxis in zebrafish is a hardwired navigational behavior, performed at a stage when larvae swim by using a small repertoire of stereotyped movements. We established conditions to elicit robust phototaxis behavior and found that zebrafish larvae deploy directional orienting maneuvers and regulate forward swimming speed to navigate toward a target light. Using genetic analysis and targeted laser ablations, we show that retinal ON and OFF pathways play distinct roles during phototaxis. The retinal OFF pathway controls turn movements via retinotectal projections and establishes correct orientation by causing larvae to turn away from nontarget areas. In contrast, the retinal ON pathway activates the serotonergic system to trigger rapid forward swimming toward the target. Computational simulation of phototaxis with an OFF-turn, ON-approach algorithm verifies that our model accounts for key features of phototaxis and provides a simple and robust mechanism for behavioral choice between competing targets. Copyright 2010 Elsevier Ltd. All rights reserved.

  13. A sub-target approach to the kinodynamic motion control of a wheeled mobile robot

    NASA Astrophysics Data System (ADS)

    Motonaka, Kimiko; Watanabe, Keigo; Maeyama, Shoichi

    2018-02-01

    A mobile robot with two independently driven wheels is popular, but it is difficult to stabilize it by a continuous controller with a constant gain, due to its nonholonomic property. It is guaranteed that a nonholonomic controlled object can always be converged to an arbitrary point using a switching control method or a quasi-continuous control method based on an invariant manifold in a chained form. From this, the authors already proposed a kinodynamic controller to converge the states of such a two-wheeled mobile robot to the arbitrary target position while avoiding obstacles, by combining the control based on the invariant manifold and the harmonic potential field (HPF). On the other hand, it was confirmed in the previous research that there is a case that the robot cannot avoid the obstacle because there is no enough space to converge the current state to the target state. In this paper, we propose a method that divides the final target position into some sub-target positions and moves the robot step by step, and it is confirmed by the simulation that the robot can converge to the target position while avoiding obstacles using the proposed method.

  14. Not All Attention Orienting is Created Equal: Recognition Memory is Enhanced When Attention Orienting Involves Distractor Suppression

    PubMed Central

    Markant, Julie; Worden, Michael S.; Amso, Dima

    2015-01-01

    Learning through visual exploration often requires orienting of attention to meaningful information in a cluttered world. Previous work has shown that attention modulates visual cortex activity, with enhanced activity for attended targets and suppressed activity for competing inputs, thus enhancing the visual experience. Here we examined the idea that learning may be engaged differentially with variations in attention orienting mechanisms that drive driving eye movements during visual search and exploration. We hypothesized that attention orienting mechanisms that engaged suppression of a previously attended location will boost memory encoding of the currently attended target objects to a greater extent than those that involve target enhancement alone To test this hypothesis we capitalized on the classic spatial cueing task and the inhibition of return (IOR) mechanism (Posner, Rafal, & Choate, 1985; Posner, 1980) to demonstrate that object images encoded in the context of concurrent suppression at a previously attended location were encoded more effectively and remembered better than those encoded without concurrent suppression. Furthermore, fMRI analyses revealed that this memory benefit was driven by attention modulation of visual cortex activity, as increased suppression of the previously attended location in visual cortex during target object encoding predicted better subsequent recognition memory performance. These results suggest that not all attention orienting impacts learning and memory equally. PMID:25701278

  15. An assessment of auditory-guided locomotion in an obstacle circumvention task.

    PubMed

    Kolarik, Andrew J; Scarfe, Amy C; Moore, Brian C J; Pardhan, Shahina

    2016-06-01

    This study investigated how effectively audition can be used to guide navigation around an obstacle. Ten blindfolded normally sighted participants navigated around a 0.6 × 2 m obstacle while producing self-generated mouth click sounds. Objective movement performance was measured using a Vicon motion capture system. Performance with full vision without generating sound was used as a baseline for comparison. The obstacle's location was varied randomly from trial to trial: it was either straight ahead or 25 cm to the left or right relative to the participant. Although audition provided sufficient information to detect the obstacle and guide participants around it without collision in the majority of trials, buffer space (clearance between the shoulder and obstacle), overall movement times, and number of velocity corrections were significantly (p < 0.05) greater with auditory guidance than visual guidance. Collisions sometime occurred under auditory guidance, suggesting that audition did not always provide an accurate estimate of the space between the participant and obstacle. Unlike visual guidance, participants did not always walk around the side that afforded the most space during auditory guidance. Mean buffer space was 1.8 times higher under auditory than under visual guidance. Results suggest that sound can be used to generate buffer space when vision is unavailable, allowing navigation around an obstacle without collision in the majority of trials.

  16. Real-time obstacle avoidance using harmonic potential functions

    NASA Technical Reports Server (NTRS)

    Kim, Jin-Oh; Khosla, Pradeep K.

    1992-01-01

    This paper presents a new formulation of the artificial potential approach to the obstacle avoidance problem for a mobile robot or a manipulator in a known environment. Previous formulations of artificial potentials for obstacle avoidance have exhibited local minima in a cluttered environment. To build an artificial potential field, harmonic functions that completely eliminate local minima even for a cluttered environment are used. The panel method is employed to represent arbitrarily shaped obstacles and to derive the potential over the whole space. Based on this potential function, an elegant control strategy is proposed for the real-time control of a robot. The harmonic potential, the panel method, and the control strategy are tested with a bar-shaped mobile robot and a three-degree-of-freedom planar redundant manipulator.

  17. A Real-Time Reaction Obstacle Avoidance Algorithm for Autonomous Underwater Vehicles in Unknown Environments.

    PubMed

    Yan, Zheping; Li, Jiyun; Zhang, Gengshi; Wu, Yi

    2018-02-02

    A novel real-time reaction obstacle avoidance algorithm (RRA) is proposed for autonomous underwater vehicles (AUVs) that must adapt to unknown complex terrains, based on forward looking sonar (FLS). To accomplish this algorithm, obstacle avoidance rules are planned, and the RRA processes are split into five steps Introduction only lists 4 so AUVs can rapidly respond to various environment obstacles. The largest polar angle algorithm (LPAA) is designed to change detected obstacle's irregular outline into a convex polygon, which simplifies the obstacle avoidance process. A solution is designed to solve the trapping problem existing in U-shape obstacle avoidance by an outline memory algorithm. Finally, simulations in three unknown obstacle scenes are carried out to demonstrate the performance of this algorithm, where the obtained obstacle avoidance trajectories are safety, smooth and near-optimal.

  18. Strategic Orientation in the Globalization of Software Firms

    NASA Astrophysics Data System (ADS)

    Dedrick, Jason; Kraemer, Kenneth L.; Carmel, Erran; Dunkle, Debora

    In the search for profits, software firms are globalizing their development activities. Some firms achieve greater profits by becoming more efficient, whereas others do so by reaching new markets; some do both. This paper creates an a priori typology of strategies based on the extent to which firms are focused on operational improvement or market access, have a dual focus or are unfocused. We find that firms with these strategies differ in degree of internationalization, organization of offshoring and performance outcomes related to offshoring. Market-oriented firms receive a greater proportion of their total revenue from sales outside the U.S., showing a greater international orientation. They keep more of their offshore development in-house via captive operations. They also are most likely to report increased non-U.S. sales as a result of offshoring. On the other hand, operations-oriented firms have lower levels of international sales, are more likely to go offshore via outsourced software development, and achieve greater costs savings and labor force flexibility as a result of offshoring. Operations-oriented firms also face more obstacles in offshoring, perhaps because of their reliance on outsourcing. Dual focus firms generally achieve some of the best of both strategies, whereas unfocused firms achieve lower cost benefits.

  19. The relationship between operative and radiographic acetabular component orientation: which factors influence resultant cup orientation?

    PubMed

    Grammatopoulos, G; Pandit, H G; da Assunção, R; McLardy-Smith, P; De Smet, K A; Gill, H S; Murray, D W

    2014-10-01

    There is great variability in acetabular component orientation following hip replacement. The aims of this study were to compare the component orientation at impaction with the orientation measured on post-operative radiographs and identify factors that influence the difference between the two. A total of 67 hip replacements (52 total hip replacements and 15 hip resurfacings) were prospectively studied. Intra-operatively, the orientation of the acetabular component after impaction relative to the operating table was measured using a validated stereo-photogrammetry protocol. Post-operatively, the radiographic orientation was measured; the mean inclination/anteversion was 43° (sd 6°)/ 19° (sd 7°). A simulated radiographic orientation was calculated based on how the orientation would have appeared had an on-table radiograph been taken intra-operatively. The mean difference between radiographic and intra-operative inclination/anteversion was 5° (sd 5°)/ -8° (sd 8°). The mean difference between simulated radiographic and intra-operative inclination/anteversion, which quantifies the effect of the different way acetabular orientation is measured, was 3°/-6° (sd 2°). The mean difference between radiographic and simulated radiographic orientation inclination/anteversion, which is a manifestation of the change in pelvic position between component impaction and radiograph, was 1°/-2° (sd 7°). This study demonstrated that in order to achieve a specific radiographic orientation target, surgeons should implant the acetabular component 5° less inclined and 8° more anteverted than their target. Great variability (2 sd about ± 15°) in the post-operative radiographic cup orientation was seen. The two equally contributing causes for this are variability in the orientation at which the cup is implanted, and the change in pelvic position between impaction and post-operative radiograph. ©2014 The British Editorial Society of Bone & Joint Surgery.

  20. Emerging therapeutic targets in metastatic progression: a focus on breast cancer

    PubMed Central

    Li, Zhuo; Kang, Yibin

    2016-01-01

    Metastasis is the underlying cause of death for the majority of breast cancer patients. Despite significant advances in recent years in basic research and clinical development, therapies that specifically target metastatic breast cancer remain inadequate, and represents the single greatest obstacle to reducing mortality of late-stage breast cancer. Recent efforts have leveraged genomic analysis of breast cancer and molecular dissection of tumor-stromal cross-talk to uncover a number of promising candidates for targeted treatment of metastatic breast cancer. Rational combinations of therapeutic agents targeting tumor-intrinsic properties and microenvironmental components provide a promising strategy to develop precision treatments with higher specificity and less toxicity. In this review, we discuss the emerging therapeutic targets in breast cancer metastasis, from tumor-intrinsic pathways to those that involve the host tissue components, including the immune system. PMID:27000769

  1. A game theory-based obstacle avoidance routing protocol for wireless sensor networks.

    PubMed

    Guan, Xin; Wu, Huayang; Bi, Shujun

    2011-01-01

    The obstacle avoidance problem in geographic forwarding is an important issue for location-based routing in wireless sensor networks. The presence of an obstacle leads to several geographic routing problems such as excessive energy consumption and data congestion. Obstacles are hard to avoid in realistic environments. To bypass obstacles, most routing protocols tend to forward packets along the obstacle boundaries. This leads to a situation where the nodes at the boundaries exhaust their energy rapidly and the obstacle area is diffused. In this paper, we introduce a novel routing algorithm to solve the obstacle problem in wireless sensor networks based on a game-theory model. Our algorithm forms a concave region that cannot forward packets to achieve the aim of improving the transmission success rate and decreasing packet transmission delays. We consider the residual energy, out-degree and forwarding angle to determine the forwarding probability and payoff function of forwarding candidates. This achieves the aim of load balance and reduces network energy consumption. Simulation results show that based on the average delivery delay, energy consumption and packet delivery ratio performances our protocol is superior to other traditional schemes.

  2. Research on robot mobile obstacle avoidance control based on visual information

    NASA Astrophysics Data System (ADS)

    Jin, Jiang

    2018-03-01

    Robots to detect obstacles and control robots to avoid obstacles has been a key research topic of robot control. In this paper, a scheme of visual information acquisition is proposed. By judging visual information, the visual information is transformed into the information source of path processing. In accordance with the established route, in the process of encountering obstacles, the algorithm real-time adjustment trajectory to meet the purpose of intelligent control of mobile robots. Simulation results show that, through the integration of visual sensing information, the obstacle information is fully obtained, while the real-time and accuracy of the robot movement control is guaranteed.

  3. Meanline Analysis of Turbines with Choked Flow in the Object-Oriented Turbomachinery Analysis Code

    NASA Technical Reports Server (NTRS)

    Hendricks, Eric S.

    2016-01-01

    The Object-Oriented Turbomachinery Analysis Code (OTAC) is a new meanline/streamline turbomachinery modeling tool being developed at NASA GRC. During the development process, a limitation of the code was discovered in relation to the analysis of choked flow in axial turbines. This paper describes the relevant physics for choked flow as well as the changes made to OTAC to enable analysis in this flow regime.

  4. Optimal layout design of obstacles for panic evacuation using differential evolution

    NASA Astrophysics Data System (ADS)

    Zhao, Yongxiang; Li, Meifang; Lu, Xin; Tian, Lijun; Yu, Zhiyong; Huang, Kai; Wang, Yana; Li, Ting

    2017-01-01

    To improve the pedestrian outflow in panic situations by suitably placing an obstacle in front of the exit, it is vital to understand the physical mechanism behind the evacuation efficiency enhancement. In this paper, a robust differential evolution is firstly employed to optimize the geometrical parameters of different shaped obstacles in order to achieve an optimal evacuation efficiency. Moreover, it is found that all the geometrical parameters of obstacles could markedly influence the evacuation efficiency of pedestrians, and the best way for achieving an optimal pedestrian outflow is to slightly shift the obstacle from the center of the exit which is consistent with findings of extant literature. Most importantly, by analyzing the profiles of density, velocity and specific flow, as well as the spatial distribution of crowd pressure, we have proven that placing an obstacle in panic situations does not reduce or absorb the pressure in the region of exit, on the contrary, promotes the pressure to a much higher level, hence the physical mechanism behind the evacuation efficiency enhancement is not a pressure decrease in the region of exit, but a significant reduction of high density region by effective separation in space which finally causes the increasing of escape speed and evacuation outflow. Finally, it is clearly demonstrated that the panel-like obstacle is considerably more robust and stable than the pillar-like obstacle to guarantee the enhancement of evacuation efficiency under different initial pedestrian distributions, different initial crowd densities as well as different desired velocities.

  5. Gendered Obstacles Faced by Historical Women in Physics and Astronomy

    NASA Astrophysics Data System (ADS)

    Jones, Kristen M.

    2007-12-01

    A gender gap still exists in modern science; this is especially evident in the fields of physics and astronomy. The cause of such a gap is the center of debate. Is this discrepancy the result of inherent ability or socialization? Most studies have focused on modern issues and how women are socialized today. The role of historical gender perspectives and social opinions in creating the field of modern science and any discrepancies within it has not yet been explored in depth. This project investigates the obstacles faced by historical women in physics and astronomy that stem from the officialized gender biases that accompanied the establishment of modern science. Such obstacles are both formal and informal. Four women were chosen to span the three hundred year period between the standardization of the field and the modern day: Laura Bassi, Mary Somerville, Lise Meitner, and Jocelyn Bell Burnell. The investigation reveals that formal obstacles significantly decreased over the time period, while informal obstacles eroded more gradually. Obstacles also reflected historical events such as the World Wars and the Enlightenment. Trends in obstacles faced by four prominent women physicists indicate that education, finances, support networks, and social opinion played a large role in determining success in the field. The applicability to modern day physics issues and the gender gap is discussed. Many thanks to the Pathways Scholars Program and the Ronald E. McNair Post-Baccalaureate Achievement Program for funding for this project.

  6. Bim-Based Indoor Path Planning Considering Obstacles

    NASA Astrophysics Data System (ADS)

    Xu, M.; Wei, S.; Zlatanova, S.; Zhang, R.

    2017-09-01

    At present, 87 % of people's activities are in indoor environment; indoor navigation has become a research issue. As the building structures for people's daily life are more and more complex, many obstacles influence humans' moving. Therefore it is essential to provide an accurate and efficient indoor path planning. Nowadays there are many challenges and problems in indoor navigation. Most existing path planning approaches are based on 2D plans, pay more attention to the geometric configuration of indoor space, often ignore rich semantic information of building components, and mostly consider simple indoor layout without taking into account the furniture. Addressing the above shortcomings, this paper uses BIM (IFC) as the input data and concentrates on indoor navigation considering obstacles in the multi-floor buildings. After geometric and semantic information are extracted, 2D and 3D space subdivision methods are adopted to build the indoor navigation network and to realize a path planning that avoids obstacles. The 3D space subdivision is based on triangular prism. The two approaches are verified by the experiments.

  7. Obstacle avoidance system with sonar sensing and fuzzy logic

    NASA Astrophysics Data System (ADS)

    Chiang, Wen-chuan; Kelkar, Nikhal; Hall, Ernest L.

    1997-09-01

    Automated guided vehicles (AGVs) have many potential applications in manufacturing, medicine, space and defense. The purpose of this paper is to describe exploratory research on the design of an obstacle avoidance system using sonar sensors for a modular autonomous mobile robot controller. The advantages of a modular system are related to portability and the fact that any vehicle can become autonomous with minimal modifications. A mobile robot test-bed has been constructed using a golf cart base. The obstacle avoidance system is based on a micro-controller interfaced with multiple ultrasonic transducers. This micro-controller independently handles all timing and distance calculations and sends a distance measurement back to the computer via the serial line. This design yields a portable independent system. Testing of these systems has been done in the lab as well as on an outside test track with positive results that show that at five mph the vehicle can follow a line and at the same time avoid obstacles. This design, in its modularity, creates a portable autonomous obstacle avoidance controller applicable for any mobile vehicle with only minor adaptations.

  8. Obstacles to Developing Digital Literacy on the Internet in Middle School Science Instruction

    ERIC Educational Resources Information Center

    Colwell, Jamie; Hunt-Barron, Sarah; Reinking, David

    2013-01-01

    Obstacles, and instructional responses to them, that emerged in two middle school science classes during a formative experiment investigating Internet Reciprocal Teaching (IRT), an instructional intervention aimed at increasing digital literacy on the Internet, are reported in this manuscript. Analysis of qualitative data revealed that IRT enabled…

  9. Sided functions of an arginine-agmatine antiporter oriented in liposomes.

    PubMed

    Tsai, Ming-Feng; Fang, Yiling; Miller, Christopher

    2012-02-28

    The arginine-dependent extreme acid resistance system helps enteric bacteria survive the harsh gastric environment. At the center of this multiprotein system is an arginine-agmatine antiporter, AdiC. To maintain cytoplasmic pH, AdiC imports arginine and exports its decarboxylated product, agmatine, resulting in a net extrusion of one "virtual proton" in each turnover. The random orientation of AdiC in reconstituted liposomes throws up an obstacle to quantifying its transport mechanism. To overcome this problem, we introduced a mutation, S26C, near the substrate-binding site. This mutant exhibits substrate recognition and pH-dependent activity similar to those of the wild-type protein but loses function completely upon reaction with thiol reagents. The membrane-impermeant MTSES reagent can then be used as a cleanly sided inhibitor to silence those S26C-AdiC proteins whose extracellular portion projects from the external side of the liposome. Alternatively, the membrane-permeant MTSEA and membrane-impermeant reducing reagent, TCEP, can be used together to inhibit proteins in the opposite orientation. This approach allows steady-state kinetic analysis of AdiC in a sided fashion. Arginine and agmatine have similar Michaelis-Menten parameters for both sides of the protein, while the extracellular side selects arginine over argininamide, a mimic of the carboxylate-protonated form of arginine, more effectively than does the cytoplasmic side. Moreover, the two sides of AdiC have different pH sensitivities. AdiC activity increases to a plateau at pH 4 as the extracellular side is acidified, while the cytoplasmic side shows an optimal pH of 5.5, with further acidification inhibiting transport. This oriented system allows more precise analysis of AdiC-mediated substrate transport than has been previously available and permits comparison to the situation experienced by the bacterial membrane under acid stress.

  10. Automatic Quadcopter Control Avoiding Obstacle Using Camera with Integrated Ultrasonic Sensor

    NASA Astrophysics Data System (ADS)

    Anis, Hanafi; Haris Indra Fadhillah, Ahmad; Darma, Surya; Soekirno, Santoso

    2018-04-01

    Automatic navigation on the drone is being developed these days, a wide variety of types of drones and its automatic functions. Drones used in this study was an aircraft with four propellers or quadcopter. In this experiment, image processing used to recognize the position of an object and ultrasonic sensor used to detect obstacle distance. The method used to trace an obsctacle in image processing was the Lucas-Kanade-Tomasi Tracker, which had been widely used due to its high accuracy. Ultrasonic sensor used to complement the image processing success rate to be fully detected object. The obstacle avoidance system was to observe at the program decisions from some obstacle conditions read by the camera and ultrasonic sensors. Visual feedback control based PID controllers are used as a control of drones movement. The conclusion of the obstacle avoidance system was to observe at the program decisions from some obstacle conditions read by the camera and ultrasonic sensors.

  11. Recognition of three dimensional obstacles by an edge detection scheme. [for Mars roving vehicle using laser range finder

    NASA Technical Reports Server (NTRS)

    Reed, M. A.

    1974-01-01

    The need for an obstacle detection system on the Mars roving vehicle was assumed, and a practical scheme was investigated and simulated. The principal sensing device on this vehicle was taken to be a laser range finder. Both existing and original algorithms, ending with thresholding operations, were used to obtain the outlines of obstacles from the raw data of this laser scan. A theoretical analysis was carried out to show how proper value of threshold may be chosen. Computer simulations considered various mid-range boulders, for which the scheme was quite successful. The extension to other types of obstacles, such as craters, was considered. The special problems of bottom edge detection and scanning procedure are discussed.

  12. Relationship-Enhancing Communication Skills in Prime-Time Family-Oriented Situation Comedies.

    ERIC Educational Resources Information Center

    Aust, Charles F.

    Television situation comedies have been criticized for their portrayal of dysfunctional family behavior. An exploratory content analysis study assessed the extent of relationship-enhancing communication skills in family-oriented, prime-time situation comedies, a genre frequently targeted for both scorn and praise. Three episodes each of five shows…

  13. Apparatus for obstacle traversion

    DOEpatents

    Borenstein, Johann

    2004-08-10

    An apparatus for traversing obstacles having an elongated, round, flexible body that includes a plurality of drive track assemblies. The plurality of drive track assemblies cooperate to provide forward propulsion wherever a propulsion member is in contact with any feature of the environment, regardless of how many or which ones of the plurality of drive track assemblies make contact with such environmental feature.

  14. Assistive peripheral phosphene arrays deliver advantages in obstacle avoidance in simulated end-stage retinitis pigmentosa: a virtual-reality study

    NASA Astrophysics Data System (ADS)

    Zapf, Marc Patrick H.; Boon, Mei-Ying; Lovell, Nigel H.; Suaning, Gregg J.

    2016-04-01

    Objective. The prospective efficacy of peripheral retinal prostheses for guiding orientation and mobility in the absence of residual vision, as compared to an implant for the central visual field (VF), was evaluated using simulated prosthetic vision (SPV). Approach. Sighted volunteers wearing a head-mounted display performed an obstacle circumvention task under SPV. Mobility and orientation performance with three layouts of prosthetic vision were compared: peripheral prosthetic vision of higher visual acuity (VA) but limited VF, of wider VF but limited VA, as well as centrally restricted prosthetic vision. Learning curves using these layouts were compared fitting an exponential model to the mobility and orientation measures. Main results. Using peripheral layouts, performance was superior to the central layout. Walking speed with both higher-acuity and wider-angle layouts was 5.6% higher, and mobility errors reduced by 46.4% and 48.6%, respectively, as compared to the central layout. The wider-angle layout yielded the least number of collisions, 63% less than the higher-acuity and 73% less than the central layout. Using peripheral layouts, the number of visual-scanning related head movements was 54.3% (higher-acuity) and 60.7% (wider-angle) lower, as compared to the central layout, and the ratio of time standing versus time walking was 51.9% and 61.5% lower, respectively. Learning curves did not differ between layouts, except for time standing versus time walking, where both peripheral layouts achieved significantly lower asymptotic values compared to the central layout. Significance. Beyond complementing residual vision for an improved performance, peripheral prosthetic vision can effectively guide mobility in the later stages of retinitis pigmentosa (RP) without residual vision. Further, the temporal dynamics of learning peripheral and central prosthetic vision are similar. Therefore, development of a peripheral retinal prosthesis and early implantation to

  15. Concentration of Swiss Elite Orienteers.

    ERIC Educational Resources Information Center

    Seiler, Roland; Wetzel, Jorg

    1997-01-01

    A visual discrimination task was used to measure concentration among 43 members of Swiss national orienteering teams. Subjects were above average in the number of target objects dealt with and in duration of continuous concentration. For females only, ranking in orienteering performance was related to quality of concentration (ratio of correct to…

  16. Not all attention orienting is created equal: recognition memory is enhanced when attention orienting involves distractor suppression.

    PubMed

    Markant, Julie; Worden, Michael S; Amso, Dima

    2015-04-01

    Learning through visual exploration often requires orienting of attention to meaningful information in a cluttered world. Previous work has shown that attention modulates visual cortex activity, with enhanced activity for attended targets and suppressed activity for competing inputs, thus enhancing the visual experience. Here we examined the idea that learning may be engaged differentially with variations in attention orienting mechanisms that drive eye movements during visual search and exploration. We hypothesized that attention orienting mechanisms that engaged suppression of a previously attended location would boost memory encoding of the currently attended target objects to a greater extent than those that involve target enhancement alone. To test this hypothesis we capitalized on the classic spatial cueing task and the inhibition of return (IOR) mechanism (Posner, 1980; Posner, Rafal, & Choate, 1985) to demonstrate that object images encoded in the context of concurrent suppression at a previously attended location were encoded more effectively and remembered better than those encoded without concurrent suppression. Furthermore, fMRI analyses revealed that this memory benefit was driven by attention modulation of visual cortex activity, as increased suppression of the previously attended location in visual cortex during target object encoding predicted better subsequent recognition memory performance. These results suggest that not all attention orienting impacts learning and memory equally. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Autonomous Rover Traverse and Precise Arm Placement on Remotely Designated Targets

    NASA Technical Reports Server (NTRS)

    Nesnas, Issa A.; Pivtoraiko, Mihail N.; Kelly, Alonzo; Fleder, Michael

    2012-01-01

    This software controls a rover platform to traverse rocky terrain autonomously, plan paths, and avoid obstacles using its stereo hazard and navigation cameras. It does so while continuously tracking a target of interest selected from 10 20 m away. The rover drives and tracks the target until it reaches the vicinity of the target. The rover then positions itself to approach the target, deploys its robotic arm, and places the end effector instrument on the designated target to within 2-3-cm accuracy of the originally selected target. This software features continuous navigation in a fairly rocky field in an outdoor environment and the ability to enable the rover to avoid large rocks and traverse over smaller ones. Using point-and-click mouse commands, a scientist designates targets in the initial imagery acquired from the rover s mast cameras. The navigation software uses stereo imaging, traversability analysis, path planning, trajectory generation, and trajectory execution. It also includes visual target tracking of a designated target selected from 10 m away while continuously navigating the rocky terrain. Improvements in this design include steering while driving, which uses continuous curvature paths. There are also several improvements to the traversability analyzer, including improved data fusion of traversability maps that result from pose estimation uncertainties, dealing with boundary effects to enable tighter maneuvers, and handling a wider range of obstacles. This work advances what has been previously developed and integrated on the Mars Exploration Rovers by using algorithms that are capable of traversing more rock-dense terrains, enabling tight, thread-the-needle maneuvers. These algorithms were integrated on the newly refurbished Athena Mars research rover, and were fielded in the JPL Mars Yard. Forty-three runs were conducted with targets at distances ranging from 5 to 15 m, and a success rate of 93% was achieved for placement of the instrument within

  18. A target oriented expeditious approach towards synthesis of certain bacterial rare sugar derivatives.

    PubMed

    Chaudhury, Aritra; Ghosh, Rina

    2017-02-07

    Bacterial rare amino deoxy sugars are found in the cell surface polysaccharides of multiple pathogenic bacterial strains, but are absent in the human metabolism. This helps in the differentiation between pathogens and host cells which can be exploited for target specific drug discovery and carbohydrate based vaccine development. The principal bacterial atypical sugar derivatives include 2-acetamido-4-amino-2,4,6-trideoxy-d-galactose (AAT), 2,4-diacetamido-2,4,6-trideoxy-d-galactose (DATDG) and N-acetylfucosamine (FucNAc). Herein, a highly streamlined protocol leading to the aforesaid derivatives is presented. The highlights of the method lie in radical mediated 6-deoxygenation along with a one-pot like protection profile manipulation on suitably derivatised d-glucosamine or d-mannose motifs to obtain a vital quinovosaminoside or rhamnoside from which rare sugar derivatives were synthesized in a diversity oriented manner.

  19. Orientation masking and cross-orientation suppression (XOS): implications for estimates of filter bandwidth.

    PubMed

    Meese, Tim S; Holmes, David J

    2010-10-01

    Most contemporary models of spatial vision include a cross-oriented route to suppression (masking from a broadly tuned inhibitory pool), which is most potent at low spatial and high temporal frequencies (T. S. Meese & D. J. Holmes, 2007). The influence of this pathway can elevate orientation-masking functions without exciting the target mechanism, and because early psychophysical estimates of filter bandwidth did not accommodate this, it is likely that they have been overestimated for this corner of stimulus space. Here we show that a transient 40% contrast mask causes substantial binocular threshold elevation for a transient vertical target, and this declines from a mask orientation of 0° to about 40° (indicating tuning), and then more gently to 90°, where it remains at a factor of ∼4. We also confirm that cross-orientation masking is diminished or abolished at high spatial frequencies and for sustained temporal modulation. We fitted a simple model of pedestal masking and cross-orientation suppression (XOS) to our data and those of G. C. Phillips and H. R. Wilson (1984) and found the dependency of orientation bandwidth on spatial frequency to be much less than previously supposed. An extension of our linear spatial pooling model of contrast gain control and dilution masking (T. S. Meese & R. J. Summers, 2007) is also shown to be consistent with our results using filter bandwidths of ±20°. Both models include tightly and broadly tuned components of divisive suppression. More generally, because XOS and/or dilution masking can affect the shape of orientation-masking curves, we caution that variations in bandwidth estimates might reflect variations in processes that have nothing to do with filter bandwidth.

  20. Generation of spiral waves pinned to obstacles in a simulated excitable system

    NASA Astrophysics Data System (ADS)

    Phantu, Metinee; Kumchaiseemak, Nakorn; Porjai, Porramain; Sutthiopad, Malee; Müller, Stefan C.; Luengviriya, Chaiya; Luengviriya, Jiraporn

    2017-09-01

    Pinning phenomena emerge in many dynamical systems. They are found to stabilize extreme conditions such as superconductivity and super fluidity. The dynamics of pinned spiral waves, whose tips trace the boundary of obstacles, also play an important role in the human health. In heart, such pinned waves cause longer tachycardia. In this article, we present two methods for generating pinned spiral waves in a simulated excitable system. In method A, an obstacle is set in the system prior to an ignition of a spiral wave. This method may be suitable only for the case of large obstacles since it often fails when used for small obstacles. In method B, a spiral wave is generated before an obstacle is placed at the spiral tip. With this method, a pinned spiral wave is always obtained, regardless the obstacle size. We demonstrate that after a transient interval the dynamics of the pinned spiral waves generated by the methods A and B are identical. The initiation of pinned spiral waves in both two- and three-dimensional systems is illustrated.

  1. Quantitative analysis of microtubule orientation in interdigitated leaf pavement cells

    PubMed Central

    Akita, Kae; Higaki, Takumi; Kutsuna, Natsumaro; Hasezawa, Seiichiro

    2015-01-01

    Leaf pavement cells are shaped like a jigsaw puzzle in most dicotyledon species. Molecular genetic studies have identified several genes required for pavement cells morphogenesis and proposed that microtubules play crucial roles in the interdigitation of pavement cells. In this study, we performed quantitative analysis of cortical microtubule orientation in leaf pavement cells in Arabidopsis thaliana. We captured confocal images of cortical microtubules in cotyledon leaf epidermis expressing GFP-tubulinβ and quantitatively evaluated the microtubule orientations relative to the pavement cell growth axis using original image processing techniques. Our results showed that microtubules kept parallel orientations to the growth axis during pavement cell growth. In addition, we showed that immersion treatment of seed cotyledons in solutions containing tubulin polymerization and depolymerization inhibitors decreased pavement cell complexity. Treatment with oryzalin and colchicine inhibited the symmetric division of guard mother cells. PMID:26039484

  2. Quantitative analysis of microtubule orientation in interdigitated leaf pavement cells.

    PubMed

    Akita, Kae; Higaki, Takumi; Kutsuna, Natsumaro; Hasezawa, Seiichiro

    2015-01-01

    Leaf pavement cells are shaped like a jigsaw puzzle in most dicotyledon species. Molecular genetic studies have identified several genes required for pavement cells morphogenesis and proposed that microtubules play crucial roles in the interdigitation of pavement cells. In this study, we performed quantitative analysis of cortical microtubule orientation in leaf pavement cells in Arabidopsis thaliana. We captured confocal images of cortical microtubules in cotyledon leaf epidermis expressing GFP-tubulinβ and quantitatively evaluated the microtubule orientations relative to the pavement cell growth axis using original image processing techniques. Our results showed that microtubules kept parallel orientations to the growth axis during pavement cell growth. In addition, we showed that immersion treatment of seed cotyledons in solutions containing tubulin polymerization and depolymerization inhibitors decreased pavement cell complexity. Treatment with oryzalin and colchicine inhibited the symmetric division of guard mother cells.

  3. Targeting the undruggable: Advances and obstacles in current RNAi therapy

    PubMed Central

    Wu, Sherry Y.; Lopez-Berestein, Gabriel; Calin, George A.; Sood, Anil K.

    2014-01-01

    RNA interference (RNAi) therapeutics represents a rapidly emerging platform for personalized cancer treatment. Recent advances in delivery, target selection, and safety of RNAi cancer therapy provide unprecedented opportunities for clinical translation. Here, we discuss these advances and present strategies for making RNAi-based therapy a viable part of cancer management. PMID:24920658

  4. Orientation selective deep brain stimulation

    NASA Astrophysics Data System (ADS)

    Lehto, Lauri J.; Slopsema, Julia P.; Johnson, Matthew D.; Shatillo, Artem; Teplitzky, Benjamin A.; Utecht, Lynn; Adriany, Gregor; Mangia, Silvia; Sierra, Alejandra; Low, Walter C.; Gröhn, Olli; Michaeli, Shalom

    2017-02-01

    Objective. Target selectivity of deep brain stimulation (DBS) therapy is critical, as the precise locus and pattern of the stimulation dictates the degree to which desired treatment responses are achieved and adverse side effects are avoided. There is a clear clinical need to improve DBS technology beyond currently available stimulation steering and shaping approaches. We introduce orientation selective neural stimulation as a concept to increase the specificity of target selection in DBS. Approach. This concept, which involves orienting the electric field along an axonal pathway, was tested in the corpus callosum of the rat brain by freely controlling the direction of the electric field on a plane using a three-electrode bundle, and monitoring the response of the neurons using functional magnetic resonance imaging (fMRI). Computational models were developed to further analyze axonal excitability for varied electric field orientation. Main results. Our results demonstrated that the strongest fMRI response was observed when the electric field was oriented parallel to the axons, while almost no response was detected with the perpendicular orientation of the electric field relative to the primary fiber tract. These results were confirmed by computational models of the experimental paradigm quantifying the activation of radially distributed axons while varying the primary direction of the electric field. Significance. The described strategies identify a new course for selective neuromodulation paradigms in DBS based on axonal fiber orientation.

  5. Stochastic, goal-oriented rapid impact modeling of uncertainty and environmental impacts in poorly-sampled sites using ex-situ priors

    NASA Astrophysics Data System (ADS)

    Li, Xiaojun; Li, Yandong; Chang, Ching-Fu; Tan, Benjamin; Chen, Ziyang; Sege, Jon; Wang, Changhong; Rubin, Yoram

    2018-01-01

    Modeling of uncertainty associated with subsurface dynamics has long been a major research topic. Its significance is widely recognized for real-life applications. Despite the huge effort invested in the area, major obstacles still remain on the way from theory and applications. Particularly problematic here is the confusion between modeling uncertainty and modeling spatial variability, which translates into a (mis)conception, in fact an inconsistency, in that it suggests that modeling of uncertainty and modeling of spatial variability are equivalent, and as such, requiring a lot of data. This paper investigates this challenge against the backdrop of a 7 km, deep underground tunnel in China, where environmental impacts are of major concern. We approach the data challenge by pursuing a new concept for Rapid Impact Modeling (RIM), which bypasses altogether the need to estimate posterior distributions of model parameters, focusing instead on detailed stochastic modeling of impacts, conditional to all information available, including prior, ex-situ information and in-situ measurements as well. A foundational element of RIM is the construction of informative priors for target parameters using ex-situ data, relying on ensembles of well-documented sites, pre-screened for geological and hydrological similarity to the target site. The ensembles are built around two sets of similarity criteria: a physically-based set of criteria and an additional set covering epistemic criteria. In another variation to common Bayesian practice, we update the priors to obtain conditional distributions of the target (environmental impact) dependent variables and not the hydrological variables. This recognizes that goal-oriented site characterization is in many cases more useful in applications compared to parameter-oriented characterization.

  6. TOOLS FOR OVERCOMING OBSTACLES TO REVITALIZATION: SMARTE AND START-UP

    EPA Science Inventory

    In 2001, the US-German Bilateral Working Group (BWG) identified more than 40 obstacles to site revitalization which occurred in both countries. From 2001-2005, the BWG developed tools and techniques for overcoming these obstacles. Five joint workshops were held on the following r...

  7. A Real-Time Reaction Obstacle Avoidance Algorithm for Autonomous Underwater Vehicles in Unknown Environments

    PubMed Central

    Yan, Zheping; Li, Jiyun; Zhang, Gengshi; Wu, Yi

    2018-01-01

    A novel real-time reaction obstacle avoidance algorithm (RRA) is proposed for autonomous underwater vehicles (AUVs) that must adapt to unknown complex terrains, based on forward looking sonar (FLS). To accomplish this algorithm, obstacle avoidance rules are planned, and the RRA processes are split into five steps Introduction only lists 4 so AUVs can rapidly respond to various environment obstacles. The largest polar angle algorithm (LPAA) is designed to change detected obstacle’s irregular outline into a convex polygon, which simplifies the obstacle avoidance process. A solution is designed to solve the trapping problem existing in U-shape obstacle avoidance by an outline memory algorithm. Finally, simulations in three unknown obstacle scenes are carried out to demonstrate the performance of this algorithm, where the obtained obstacle avoidance trajectories are safety, smooth and near-optimal. PMID:29393915

  8. Research on Collection System Optimal Design of Wind Farm with Obstacles

    NASA Astrophysics Data System (ADS)

    Huang, W.; Yan, B. Y.; Tan, R. S.; Liu, L. F.

    2017-05-01

    To the collection system optimal design of offshore wind farm, the factors considered are not only the reasonable configuration of the cable and switch, but also the influence of the obstacles on the topology design of the offshore wind farm. This paper presents a concrete topology optimization algorithm with obstacles. The minimal area rectangle encasing box of the obstacle is obtained by using the method of minimal area encasing box. Then the optimization algorithm combining the advantages of Dijkstra algorithm and Prim algorithm is used to gain the scheme of avoidance obstacle path planning. Finally a fuzzy comprehensive evaluation model based on the analytic hierarchy process is constructed to compare the performance of the different topologies. Case studies demonstrate the feasibility of the proposed algorithm and model.

  9. Counteracting Obstacles with Optimistic Predictions

    ERIC Educational Resources Information Center

    Zhang, Ying; Fishbach, Ayelet

    2010-01-01

    This research tested for counteractive optimism: a self-control strategy of generating optimistic predictions of future goal attainment in order to overcome anticipated obstacles in goal pursuit. In support of the counteractive optimism model, participants in 5 studies predicted better performance, more time invested in goal activities, and lower…

  10. Getting to Darwin: Obstacles to Accepting Evolution by Natural Selection

    ERIC Educational Resources Information Center

    Thagard, Paul; Findlay, Scott

    2010-01-01

    Darwin's theory of evolution by natural selection is central to modern biology, but is resisted by many people. This paper discusses the major psychological obstacles to accepting Darwin's theory. Cognitive obstacles to adopting evolution by natural selection include conceptual difficulties, methodological issues, and coherence problems that…

  11. Development Administration: Obstacles, Theories and Implications for Planning. IIEP Occasional Papers No. 2.

    ERIC Educational Resources Information Center

    Rodman, Peter W.

    In developing countries, public administration is hampered by a number of obstacles foreign to large industrialized nations. Some of these obstacles are shortages of tools and skilled personnel, outmoded organizational structures, political competition, and cultural and attitudinal barriers. The administrative obstacles and their…

  12. Nonlinear water waves generated by impulsive motion of submerged obstacle

    NASA Astrophysics Data System (ADS)

    Makarenko, N.; Kostikov, V.

    2012-04-01

    The fully nonlinear problem on generation of unsteady water waves by impulsively moving obstacle is studied analytically. The method involves the reduction of basic Euler equations to the integral-differential system for the wave elevation together with normal and tangential fluid velocities at the free surface. Exact model equations are derived in explicit form when the isolated obstacle is presented by totally submerged circular- or elliptic cylinder. Small-time asymptotic solution is constructed for the cylinder which starts moving with constant acceleration from rest. It is demonstrated that the leading-order solution terms describe several wave regimes such as the formation of non-stationary splash jets by vertical rising or vertical submersion of the obstacle, as well as the generation of diverging waves by horizontal- and combined motion of the obstacle under free surface. This work was supported by RFBR (grant No 10-01-00447) and by Research Program of the Russian Government (grant No 11.G34.31.0035).

  13. Wide-Baseline Stereo-Based Obstacle Mapping for Unmanned Surface Vehicles

    PubMed Central

    Mou, Xiaozheng; Wang, Han

    2018-01-01

    This paper proposes a wide-baseline stereo-based static obstacle mapping approach for unmanned surface vehicles (USVs). The proposed approach eliminates the complicated calibration work and the bulky rig in our previous binocular stereo system, and raises the ranging ability from 500 to 1000 m with a even larger baseline obtained from the motion of USVs. Integrating a monocular camera with GPS and compass information in this proposed system, the world locations of the detected static obstacles are reconstructed while the USV is traveling, and an obstacle map is then built. To achieve more accurate and robust performance, multiple pairs of frames are leveraged to synthesize the final reconstruction results in a weighting model. Experimental results based on our own dataset demonstrate the high efficiency of our system. To the best of our knowledge, we are the first to address the task of wide-baseline stereo-based obstacle mapping in a maritime environment. PMID:29617293

  14. Autonomous dynamic obstacle avoidance for bacteria-powered microrobots (BPMs) with modified vector field histogram.

    PubMed

    Kim, Hoyeon; Cheang, U Kei; Kim, Min Jun

    2017-01-01

    In order to broaden the use of microrobots in practical fields, autonomous control algorithms such as obstacle avoidance must be further developed. However, most previous studies of microrobots used manual motion control to navigate past tight spaces and obstacles while very few studies demonstrated the use of autonomous motion. In this paper, we demonstrated a dynamic obstacle avoidance algorithm for bacteria-powered microrobots (BPMs) using electric field in fluidic environments. A BPM consists of an artificial body, which is made of SU-8, and a high dense layer of harnessed bacteria. BPMs can be controlled using externally applied electric fields due to the electrokinetic property of bacteria. For developing dynamic obstacle avoidance for BPMs, a kinematic model of BPMs was utilized to prevent collision and a finite element model was used to characteristic the deformation of an electric field near the obstacle walls. In order to avoid fast moving obstacles, we modified our previously static obstacle avoidance approach using a modified vector field histogram (VFH) method. To validate the advanced algorithm in experiments, magnetically controlled moving obstacles were used to intercept the BPMs as the BPMs move from the initial position to final position. The algorithm was able to successfully guide the BPMs to reach their respective goal positions while avoiding the dynamic obstacles.

  15. Kinematics of the Pelvis, Torso, and Lower Limb During Obstacle Negotiation While Under Temporal Constraints.

    PubMed

    Christensen, Jesse C; Wilson, Christopher R; Merryweather, Andrew S; Foreman, K Bo

    2017-04-01

    Biomechanics of unobstructed locomotion consists of synchronized complex movements of the pelvis, torso, and lower limbs. These movement patterns become more complex as individuals encounter obstacles or negotiate uneven terrain. To date, limited research has explored how specifically the pelvis, torso, and lower limb segments relate to obstacle negotiation of varying sized objects combined with temporal constraints to perform the task. Understanding pelvis and adjoining segment movements during object negotiation will provide necessary information in identifying abnormal mechanics and potential fall risk characteristics in balance compromised patient populations. In this prospective cohort study, we aimed to compare pelvic, torso, and lower limb kinematics during unobstructed locomotion with obstacle negotiation of varying heights. Ten healthy young adults (7 females and 3 males, mean age 28.4 ± 4.1 years, mean body mass index 22.5 ± 3.6 kg/m 2 ) enrolled in this study. Analysis of within-subject differences revealed a significant increase in sagittal (posterior tilt) and frontal (ipsilateral hike) plane pelvic angular displacement and higher sagittal plane posterior torso lean angular displacement with increased obstacle height. Furthermore, both sagittal plane hip and knee maximum joint flexion were significantly higher with increasing heights of the obstacles during negotiation. These data provide insight on segment mechanics within a non-mobility-impaired population; therefore, providing a baseline to understand the kinematic demands necessary for safe and effective gait in mobility-compromised populations. Anat Rec, 300:732-738, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  16. Obstacles to TQM success in health care systems.

    PubMed

    Mosadeghrad, Ali Mohammad

    2013-01-01

    Many healthcare organisations have found it difficult to implement total quality management (TQM) successfully. The aim of this paper is to explore the barriers to TQM successful implementation in the healthcare sector. This paper reports a literature review exploring the major reasons for the failure of TQM programmes in healthcare organisations. TQM implementation and its impact depend heavily on the ability of managers to adopt and adapt its values and concepts in professional healthcare organisations. Unsuccessful TQM efforts in healthcare organisations can be attributed to the strongly departmentalised, bureaucratic and hierarchical structure, professional autonomy, tensions between managers and professionals and the difficulties involved in evaluating healthcare processes and outcomes. Other obstacles to TQM success include lack of consistent managers' and employees' commitment to and involvement in TQM implementation, poor leadership and management, lack of a quality-oriented culture, insufficient training, and inadequate resources. The review was limited to empirical articles written in the English language during the past 30 years (1980-2010). The findings of this article provide policy makers and managers with a practical understanding of the factors that are likely to obstruct TQM implementation in the healthcare sector. Understanding the factors that obstruct TQM implementation would enable managers to develop more effective strategies for implementing TQM successfully in healthcare organisations.

  17. Target-oriented retrieval of subsurface wave fields - Pushing the resolution limits in seismic imaging

    NASA Astrophysics Data System (ADS)

    Vasconcelos, Ivan; Ozmen, Neslihan; van der Neut, Joost; Cui, Tianci

    2017-04-01

    Travelling wide-bandwidth seismic waves have long been used as a primary tool in exploration seismology because they can probe the subsurface over large distances, while retaining relatively high spatial resolution. The well-known Born resolution limit often seems to be the lower bound on spatial imaging resolution in real life examples. In practice, data acquisition cost, time constraints and other factors can worsen the resolution achieved by wavefield imaging. Could we obtain images whose resolution beats the Born limits? Would it be practical to achieve it, and what are we missing today to achieve this? In this talk, we will cover aspects of linear and nonlinear seismic imaging to understand elements that play a role in obtaining "super-resolved" seismic images. New redatuming techniques, such as the Marchenko method, enable the retrieval of subsurface fields that include multiple scattering interactions, while requiring relatively little knowledge of model parameters. Together with new concepts in imaging, such as Target-Enclosing Extended Images, these new redatuming methods enable new targeted imaging frameworks. We will make a case as to why target-oriented approaches to reconstructing subsurface-domain wavefields from surface data may help in increasing the resolving power of seismic imaging, and in pushing the limits on parameter estimation. We will illustrate this using a field data example. Finally, we will draw connections between seismic and other imaging modalities, and discuss how this framework could be put to use in other applications

  18. Triangulation Based 3D Laser Imaging for Fracture Orientation Analysis

    NASA Astrophysics Data System (ADS)

    Mah, J.; Claire, S.; Steve, M.

    2009-05-01

    Laser imaging has recently been identified as a potential tool for rock mass characterization. This contribution focuses on the application of triangulation based, short-range laser imaging to determine fracture orientation and surface texture. This technology measures the distance to the target by triangulating the projected and reflected laser beams, and also records the reflection intensity. In this study, we acquired 3D laser images of rock faces using the Laser Camera System (LCS), a portable instrument developed by Neptec Design Group (Ottawa, Canada). The LCS uses an infrared laser beam and is immune to the lighting conditions. The maximum image resolution is 1024 x 1024 volumetric image elements. Depth resolution is 0.5 mm at 5 m. An above ground field trial was conducted at a blocky road cut with well defined joint sets (Kingston, Ontario). An underground field trial was conducted at the Inco 175 Ore body (Sudbury, Ontario) where images were acquired in the dark and the joint set features were more subtle. At each site, from a distance of 3 m away from the rock face, a grid of six images (approximately 1.6 m by 1.6 m) was acquired at maximum resolution with 20% overlap between adjacent images. This corresponds to a density of 40 image elements per square centimeter. Polyworks, a high density 3D visualization software tool, was used to align and merge the images into a single digital triangular mesh. The conventional method of determining fracture orientations is by manual measurement using a compass. In order to be accepted as a substitute for this method, the LCS should be capable of performing at least to the capabilities of manual measurements. To compare fracture orientation estimates derived from the 3D laser images to manual measurements, 160 inclinometer readings were taken at the above ground site. Three prominent joint sets (strike/dip: 236/09, 321/89, 325/01) were identified by plotting the joint poles on a stereonet. Underground, two main joint

  19. Workarounds and obstacles: unexpected source of innovation.

    PubMed

    Lalley, Cathy

    2014-01-01

    Nurse leaders are aware that nurses are finding ways to adapt health information technology to patient care activities. Previous literature has presented nurses' response to technology obstacles as a work-around, characterized as a negative behavior. Using narrative inquiry, this article examines 9 direct care nurses' interactions on a medical/surgical/telemetry unit. Specifically, nurses' encounters with technology obstacles will be addressed from a complexity science perspective. Four support staff including the clinical nurse manager, pharmacist, quality nurse, and project manager who is also a nurse were interviewed as part of data collection. Complexity science provides nurse leaders' insight into nurses' behavior where outcomes emerge from tensions in the environment through multidirectional and self-organizing interactions. Innovation was found when nurses responded to health information technology obstacles with self-organizing interactions, sensitivity to initial conditions, and multidirectionality. Their actions were also influenced by many sets of rules. Nurses self-organized with coworkers to find better ways to deliver care to patients when using technology. Opportunities exist for nurse leaders to facilitate interactions among nurses and other members of the organization to realize better use of health information technology that improves the patient experience.

  20. Factors Influencing Obstacle Crossing Performance in Patients with Parkinson's Disease

    PubMed Central

    Liao, Ying-Yi; Yang, Yea-Ru; Wu, Yih-Ru; Wang, Ray-Yau

    2014-01-01

    Background Tripping over obstacles is the major cause of falls in community-dwelling patients with Parkinson's disease (PD). Understanding the factors associated with the obstacle crossing behavior may help to develop possible training programs for crossing performance. This study aimed to identify the relationships and important factors determining obstacle crossing performance in patients with PD. Methods Forty-two idiopathic patients with PD (Hoehn and Yahr stages I to III) participated in this study. Obstacle crossing performance was recorded by the Liberty system, a three-dimensional motion capture device. Maximal isometric strength of the lower extremity was measured by a handheld dynamometer. Dynamic balance and sensory integration ability were assessed using the Balance Master system. Movement velocity (MV), maximal excursion (ME), and directional control (DC) were obtained during the limits of stability test to quantify dynamic balance. The sum of sensory organization test (SOT) scores was used to quantify sensory organization ability. Results Both crossing stride length and stride velocity correlated significantly with lower extremity muscle strength, dynamic balance control (forward and sideward), and sum of SOT scores. From the regression model, forward DC and ankle dorsiflexor strength were identified as two major determinants for crossing performance (R2 = .37 to.41 for the crossing stride length, R2 = .43 to.44 for the crossing stride velocity). Conclusions Lower extremity muscle strength, dynamic balance control and sensory integration ability significantly influence obstacle crossing performance. We suggest an emphasis on muscle strengthening exercises (especially ankle dorsiflexors), balance training (especially forward DC), and sensory integration training to improve obstacle crossing performance in patients with PD. PMID:24454723

  1. Acoustic basis for recognition of aspect-dependent three-dimensional targets by an echolocating bottlenose dolphin.

    PubMed

    Helweg, D A; Au, W W; Roitblat, H L; Nachtigall, P E

    1996-04-01

    The relationships between acoustic features of target echoes and the cognitive representations of the target formed by an echolocating dolphin will influence the ease with which the dolphin can recognize a target. A blindfolded Atlantic bottlenose dolphin (Tursiops truncatus) learned to match aspect-dependent three-dimensional targets (such as a cube) at haphazard orientations, although with some difficulty. This task may have been difficult because aspect-dependent targets produce different echoes at different orientations, which required the dolphin to have some capability for object constancy across changes in echo characteristics. Significant target-related differences in echo amplitude, rms bandwidth, and distributions of interhighlight intervals were observed among echoes collected when the dolphin was performing the task. Targets could be classified using a combination of energy flux density and rms bandwidth by a linear discriminant analysis and a nearest centroid classifier. Neither statistical model could classify targets without amplitude information, but the highest accuracy required spectral information as well. This suggests that the dolphin recognized the targets using a multidimensional representation containing amplitude and spectral information and that dolphins can form stable representations of targets regardless of orientation based on varying sensory properties.

  2. Malaria: Obstacles and Opportunities.

    DTIC Science & Technology

    1991-01-01

    SUBTITLE S. FUNDING NUMBERS Malaria: Obstacles and Opportunities 89PP9965 62770A 6. AUTHOR(S) 3MI62770A870 AN DA3 46085 Arthur Dennis Long 7. PERFORMING ...ORGANIZATION NAME(S) AND ADORESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER Agency for International Development New State Office Building Washignton...Hygiene and Pub- lic Health, Baltimore. \\Maryland JACQUELINE A. CATTANI. Secretary, Steering Committee of the Scientific Working Group on Applied

  3. New spatial clustering-based models for optimal urban facility location considering geographical obstacles

    NASA Astrophysics Data System (ADS)

    Javadi, Maryam; Shahrabi, Jamal

    2014-03-01

    The problems of facility location and the allocation of demand points to facilities are crucial research issues in spatial data analysis and urban planning. It is very important for an organization or governments to best locate its resources and facilities and efficiently manage resources to ensure that all demand points are covered and all the needs are met. Most of the recent studies, which focused on solving facility location problems by performing spatial clustering, have used the Euclidean distance between two points as the dissimilarity function. Natural obstacles, such as mountains and rivers, can have drastic impacts on the distance that needs to be traveled between two geographical locations. While calculating the distance between various supply chain entities (including facilities and demand points), it is necessary to take such obstacles into account to obtain better and more realistic results regarding location-allocation. In this article, new models were presented for location of urban facilities while considering geographical obstacles at the same time. In these models, three new distance functions were proposed. The first function was based on the analysis of shortest path in linear network, which was called SPD function. The other two functions, namely PD and P2D, were based on the algorithms that deal with robot geometry and route-based robot navigation in the presence of obstacles. The models were implemented in ArcGIS Desktop 9.2 software using the visual basic programming language. These models were evaluated using synthetic and real data sets. The overall performance was evaluated based on the sum of distance from demand points to their corresponding facilities. Because of the distance between the demand points and facilities becoming more realistic in the proposed functions, results indicated desired quality of the proposed models in terms of quality of allocating points to centers and logistic cost. Obtained results show promising

  4. 2D transient granular flows over obstacles: experimental and numerical work

    NASA Astrophysics Data System (ADS)

    Juez, Carmelo; Caviedes-Voullième, Daniel; Murillo, Javier; García-Navarro, Pilar

    2016-04-01

    Landslides are an ubiquitous natural hazard, and therefore human infrastructure and settlements are often at risk in mountainous regions. In order to better understand and predict landslides, systematic studies of the phenomena need to be undertaken. In particular, computational tools which allow for analysis of field problems require to be thoroughly tested, calibrated and validated under controlled conditions. And to do so, it is necessary for such controlled experiments to be fully characterized in the same terms as the numerical model requires. This work presents an experimental study of dry granular flow over a rough bed with topography which resembles a mountain valley. It has an upper region with a very high slope. The geometry of the bed describes a fourth order polynomial curve, with a low point with zero slope, and afterwards a short region with adverse slope. Obstacles are present in the lower regions which are used as model geometries of human structures. The experiments consisted of a sudden release a mass of sand on the upper region, and allowing it to flow downslope. Furthermore, it has been frequent in previous studies to measure final states of the granular mass at rest, but seldom has transient data being provided, and never for the entire field. In this work we present transient measurements of the moving granular surfaces, obtained with a consumer-grade RGB-D sensor. The sensor, developed for the videogame industry, allows to measure the moving surface of the sand, thus obtaining elevation fields. The experimental results are very consistent and repeatable. The measured surfaces clearly show the distinctive features of the granular flow around the obstacles and allow to qualitatively describe the different flow patterns. More importantly, the quantitative description of the granular surface allows for benchmarking and calibration of predictive numerical models, key in scaling the small-scale experimental knowledge into the field. In addition, as

  5. On the debate about teleology in biology: the notion of "teleological obstacle".

    PubMed

    Ribeiro, Manuel Gustavo Leitão; Larentis, Ariane Leites; Caldas, Lúcio Ayres; Garcia, Tomás Coelho; Terra, Letícia Labati; Herbst, Marcelo Hawrylak; Almeida, Rodrigo Volcan

    2015-12-01

    Among the epistemological obstacles described by Gaston Bachelard, we contend that unitary and pragmatic knowledge is correlated to the teleological categories of Ernst Mayr and is the basis for prevailing debate on the notion of "function" in biology. Given the proximity of the aspects highlighted by these authors, we propose to associate the role of teleological thinking in biology and the notion of unitary and pragmatic knowledge as an obstacle to scientific knowledge. Thus, teleological thinking persists acting as an epistemological obstacle in biology, according to Bachelardian terminology. Our investigation led us to formulate the "teleological obstacle," which we consider important for the future of biology and possibly other sciences.

  6. Obstacles Related to Structuring for Mathematization Encountered by Students When Solving Physics Problems

    ERIC Educational Resources Information Center

    Niss, Martin

    2017-01-01

    This paper studies the cognitive obstacles related to one aspect of mathematization in physics problem-solving, namely, what might be called "structuring for mathematization," where the problem situation is structured in such a way that a translation to a mathematical universe can be done. We report the results of an analysis of four…

  7. Getting to Darwin: Obstacles to Accepting Evolution by Natural Selection

    NASA Astrophysics Data System (ADS)

    Thagard, Paul; Findlay, Scott

    2010-06-01

    Darwin’s theory of evolution by natural selection is central to modern biology, but is resisted by many people. This paper discusses the major psychological obstacles to accepting Darwin’s theory. Cognitive obstacles to adopting evolution by natural selection include conceptual difficulties, methodological issues, and coherence problems that derive from the intuitiveness of alternative theories. The main emotional obstacles to accepting evolution are its apparent conflict with valued beliefs about God, souls, and morality. We draw on the philosophy of science and on a psychological theory of cognitive and emotional belief revision to make suggestions about what can be done to improve acceptance of Darwinian ideas.

  8. Trip-oriented travel time prediction (TOTTP) with historical vehicle trajectories

    NASA Astrophysics Data System (ADS)

    Xu, Tao; Li, Xiang; Claramunt, Christophe

    2018-06-01

    Accurate travel time prediction is undoubtedly of importance to both traffic managers and travelers. In highly-urbanized areas, trip-oriented travel time prediction (TOTTP) is valuable to travelers rather than traffic managers as the former usually expect to know the travel time of a trip which may cross over multiple road sections. There are two obstacles to the development of TOTTP, including traffic complexity and traffic data coverage.With large scale historical vehicle trajectory data and meteorology data, this research develops a BPNN-based approach through integrating multiple factors affecting trip travel time into a BPNN model to predict trip-oriented travel time for OD pairs in urban network. Results of experiments demonstrate that it helps discover the dominate trends of travel time changes daily and weekly, and the impact of weather conditions is non-trivial.

  9. Autonomous dynamic obstacle avoidance for bacteria-powered microrobots (BPMs) with modified vector field histogram

    PubMed Central

    Kim, Hoyeon; Cheang, U. Kei

    2017-01-01

    In order to broaden the use of microrobots in practical fields, autonomous control algorithms such as obstacle avoidance must be further developed. However, most previous studies of microrobots used manual motion control to navigate past tight spaces and obstacles while very few studies demonstrated the use of autonomous motion. In this paper, we demonstrated a dynamic obstacle avoidance algorithm for bacteria-powered microrobots (BPMs) using electric field in fluidic environments. A BPM consists of an artificial body, which is made of SU-8, and a high dense layer of harnessed bacteria. BPMs can be controlled using externally applied electric fields due to the electrokinetic property of bacteria. For developing dynamic obstacle avoidance for BPMs, a kinematic model of BPMs was utilized to prevent collision and a finite element model was used to characteristic the deformation of an electric field near the obstacle walls. In order to avoid fast moving obstacles, we modified our previously static obstacle avoidance approach using a modified vector field histogram (VFH) method. To validate the advanced algorithm in experiments, magnetically controlled moving obstacles were used to intercept the BPMs as the BPMs move from the initial position to final position. The algorithm was able to successfully guide the BPMs to reach their respective goal positions while avoiding the dynamic obstacles. PMID:29020016

  10. Human spatial orientation in the pitch dimension

    NASA Technical Reports Server (NTRS)

    Cohen, M. M.; Larson, C. A.

    1974-01-01

    Two experiments were conducted. In Experiment I, each of eight Ss attempted to place himself at 13 different goal orientations between prone and supine. Deviations of achieved body pitch angles from goal orientations were determined. In Experiment II, each of eight Ss attempted to align a visual target with his morphological horizon while he was placed at each of the 13 goal orientations. Changes in settings of the target were examined. Results indicate that Ss underestimate body pitch when they are tilted less than 60 deg backward or forward from the vertical, overestimate body pitch when they are nearly prone, and accurately estimate body pitch when they are nearly supine. In contrast, Ss set the visual target maximally above the morphological horizon when they are tilted 30 deg forward from the vertical. The findings are discussed in terms of common and different physiological mechanism that may underlie judgments of these types.

  11. A method of real-time detection for distant moving obstacles by monocular vision

    NASA Astrophysics Data System (ADS)

    Jia, Bao-zhi; Zhu, Ming

    2013-12-01

    In this paper, we propose an approach for detection of distant moving obstacles like cars and bicycles by a monocular camera to cooperate with ultrasonic sensors in low-cost condition. We are aiming at detecting distant obstacles that move toward our autonomous navigation car in order to give alarm and keep away from them. Method of frame differencing is applied to find obstacles after compensation of camera's ego-motion. Meanwhile, each obstacle is separated from others in an independent area and given a confidence level to indicate whether it is coming closer. The results on an open dataset and our own autonomous navigation car have proved that the method is effective for detection of distant moving obstacles in real-time.

  12. Obstacle Crossing Differences Between Blind and Blindfolded Subjects After Haptic Exploration.

    PubMed

    Forner-Cordero, Arturo; Garcia, Valéria D; Rodrigues, Sérgio T; Duysens, Jacques

    2016-01-01

    Little is known about the ability of blind people to cross obstacles after they have explored haptically their size and position. Long-term absence of vision may affect spatial cognition in the blind while their extensive experience with the use of haptic information for guidance may lead to compensation strategies. Seven blind and 7 sighted participants (with vision available and blindfolded) walked along a flat pathway and crossed an obstacle after a haptic exploration. Blind and blindfolded subjects used different strategies to cross the obstacle. After the first 20 trials the blindfolded subjects reduced the distance between the foot and the obstacle at the toe-off instant, while the blind behaved as the subjects with full vision. Blind and blindfolded participants showed larger foot clearance than participants with vision. At foot landing the hip was more behind the foot in the blindfolded condition, while there were no differences between the blind and the vision conditions. For several parameters of the obstacle crossing task, blind people were more similar to subjects with full vision indicating that the blind subjects were able to compensate for the lack of vision.

  13. Assisting the visually impaired: obstacle detection and warning system by acoustic feedback.

    PubMed

    Rodríguez, Alberto; Yebes, J Javier; Alcantarilla, Pablo F; Bergasa, Luis M; Almazán, Javier; Cela, Andrés

    2012-12-17

    The aim of this article is focused on the design of an obstacle detection system for assisting visually impaired people. A dense disparity map is computed from the images of a stereo camera carried by the user. By using the dense disparity map, potential obstacles can be detected in 3D in indoor and outdoor scenarios. A ground plane estimation algorithm based on RANSAC plus filtering techniques allows the robust detection of the ground in every frame. A polar grid representation is proposed to account for the potential obstacles in the scene. The design is completed with acoustic feedback to assist visually impaired users while approaching obstacles. Beep sounds with different frequencies and repetitions inform the user about the presence of obstacles. Audio bone conducting technology is employed to play these sounds without interrupting the visually impaired user from hearing other important sounds from its local environment. A user study participated by four visually impaired volunteers supports the proposed system.

  14. Assisting the Visually Impaired: Obstacle Detection and Warning System by Acoustic Feedback

    PubMed Central

    Rodríguez, Alberto; Yebes, J. Javier; Alcantarilla, Pablo F.; Bergasa, Luis M.; Almazán, Javier; Cela, Andrés

    2012-01-01

    The aim of this article is focused on the design of an obstacle detection system for assisting visually impaired people. A dense disparity map is computed from the images of a stereo camera carried by the user. By using the dense disparity map, potential obstacles can be detected in 3D in indoor and outdoor scenarios. A ground plane estimation algorithm based on RANSAC plus filtering techniques allows the robust detection of the ground in every frame. A polar grid representation is proposed to account for the potential obstacles in the scene. The design is completed with acoustic feedback to assist visually impaired users while approaching obstacles. Beep sounds with different frequencies and repetitions inform the user about the presence of obstacles. Audio bone conducting technology is employed to play these sounds without interrupting the visually impaired user from hearing other important sounds from its local environment. A user study participated by four visually impaired volunteers supports the proposed system. PMID:23247413

  15. Target identification by image analysis.

    PubMed

    Fetz, V; Prochnow, H; Brönstrup, M; Sasse, F

    2016-05-04

    Covering: 1997 to the end of 2015Each biologically active compound induces phenotypic changes in target cells that are characteristic for its mode of action. These phenotypic alterations can be directly observed under the microscope or made visible by labelling structural elements or selected proteins of the cells with dyes. A comparison of the cellular phenotype induced by a compound of interest with the phenotypes of reference compounds with known cellular targets allows predicting its mode of action. While this approach has been successfully applied to the characterization of natural products based on a visual inspection of images, recent studies used automated microscopy and analysis software to increase speed and to reduce subjective interpretation. In this review, we give a general outline of the workflow for manual and automated image analysis, and we highlight natural products whose bacterial and eucaryotic targets could be identified through such approaches.

  16. Evaluation of bending modulus of lipid bilayers using undulation and orientation analysis

    NASA Astrophysics Data System (ADS)

    Chaurasia, Adarsh K.; Rukangu, Andrew M.; Philen, Michael K.; Seidel, Gary D.; Freeman, Eric C.

    2018-03-01

    In the current paper, phospholipid bilayers are modeled using coarse-grained molecular dynamics simulations with the MARTINI force field. The extracted molecular trajectories are analyzed using Fourier analysis of the undulations and orientation vectors to establish the differences between the two approaches for evaluating the bending modulus. The current work evaluates and extends the implementation of the Fourier analysis for molecular trajectories using a weighted horizon-based averaging approach. The effect of numerical parameters in the analysis of these trajectories is explored by conducting parametric studies. Computational modeling results are validated against experimentally characterized bending modulus of lipid membranes using a shape fluctuation analysis. The computational framework is then used to estimate the bending moduli for different types of lipids (phosphocholine, phosphoethanolamine, and phosphoglycerol). This work provides greater insight into the numerical aspects of evaluating the bilayer bending modulus, provides validation for the orientation analysis technique, and explores differences in bending moduli based on differences in the lipid nanostructures.

  17. A robust close-range photogrammetric target extraction algorithm for size and type variant targets

    NASA Astrophysics Data System (ADS)

    Nyarko, Kofi; Thomas, Clayton; Torres, Gilbert

    2016-05-01

    The Photo-G program conducted by Naval Air Systems Command at the Atlantic Test Range in Patuxent River, Maryland, uses photogrammetric analysis of large amounts of real-world imagery to characterize the motion of objects in a 3-D scene. Current approaches involve several independent processes including target acquisition, target identification, 2-D tracking of image features, and 3-D kinematic state estimation. Each process has its own inherent complications and corresponding degrees of both human intervention and computational complexity. One approach being explored for automated target acquisition relies on exploiting the pixel intensity distributions of photogrammetric targets, which tend to be patterns with bimodal intensity distributions. The bimodal distribution partitioning algorithm utilizes this distribution to automatically deconstruct a video frame into regions of interest (ROI) that are merged and expanded to target boundaries, from which ROI centroids are extracted to mark target acquisition points. This process has proved to be scale, position and orientation invariant, as well as fairly insensitive to global uniform intensity disparities.

  18. 3D-Sonification for Obstacle Avoidance in Brownout Conditions

    NASA Technical Reports Server (NTRS)

    Godfroy-Cooper, M.; Miller, J. D.; Szoboszlay, Z.; Wenzel, E. M.

    2017-01-01

    Helicopter brownout is a phenomenon that occurs when making landing approaches in dusty environments, whereby sand or dust particles become swept up in the rotor outwash. Brownout is characterized by partial or total obscuration of the terrain, which degrades visual cues necessary for hovering and safe landing. Furthermore, the motion of the dust cloud produced during brownout can lead to the pilot experiencing motion cue anomalies such as vection illusions. In this context, the stability and guidance control functions can be intermittently or continuously degraded, potentially leading to undetected surface hazards and obstacles as well as unnoticed drift. Safe and controlled landing in brownout can be achieved using an integrated presentation of LADAR and RADAR imagery and aircraft state symbology. However, though detected by the LADAR and displayed on the sensor image, small obstacles can be difficult to discern from the background so that changes in obstacle elevation may go unnoticed. Moreover, pilot workload associated with tracking the displayed symbology is often so high that the pilot cannot give sufficient attention to the LADAR/RADAR image. This paper documents a simulation evaluating the use of 3D auditory cueing for obstacle avoidance in brownout as a replacement for or compliment to LADAR/RADAR imagery.

  19. Virtual obstacle crossing: Reliability and differences in stroke survivors who prospectively experienced falls or no falls.

    PubMed

    Punt, Michiel; Bruijn, Sjoerd M; Wittink, Harriet; van de Port, Ingrid G; Wubbels, Gijs; van Dieën, Jaap H

    2017-10-01

    Stroke survivors often fall during walking. To reduce fall risk, gait testing and training with avoidance of virtual obstacles is gaining popularity. However, it is unknown whether and how virtual obstacle crossing is associated with fall risk. The present study assessed whether obstacle crossing characteristics are reliable and assessed differences in stroke survivors who prospectively experienced falls or no falls. We recruited twenty-nine community dwelling chronic stroke survivors. Participants crossed five virtual obstacles with increasing lengths. After a break, the test was repeated to assess test-retest reliability. For each obstacle length and trial, we determined; success rate, leading limb preference, pre and post obstacle distance, margins of stability, toe clearance, and crossing step length and speed. Subsequently, fall incidence was monitored using a fall calendar and monthly phone calls over a six-month period. Test-retest reliability was poor, but improved with increasing obstacle-length. Twelve participants reported at least one fall. No association of fall incidence with any of the obstacle crossing characteristics was found. Given the absence of height of the virtual obstacles, obstacle avoidance may have been relatively easy, allowing participants to cross obstacles in multiple ways, increasing variability of crossing characteristics and reducing the association with fall risk. These finding cast some doubt on current protocols for testing and training of obstacle avoidance in stroke rehabilitation. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Improved prediction of antibody VL–VH orientation

    PubMed Central

    Marze, Nicholas A.; Lyskov, Sergey; Gray, Jeffrey J.

    2016-01-01

    Antibodies are important immune molecules with high commercial value and therapeutic interest because of their ability to bind diverse antigens. Computational prediction of antibody structure can quickly reveal valuable information about the nature of these antigen-binding interactions, but only if the models are of sufficient quality. To achieve high model quality during complementarity-determining region (CDR) structural prediction, one must account for the VL–VH orientation. We developed a novel four-metric VL–VH orientation coordinate frame. Additionally, we extended the CDR grafting protocol in RosettaAntibody with a new method that diversifies VL–VH orientation by using 10 VL–VH orientation templates rather than a single one. We tested the multiple-template grafting protocol on two datasets of known antibody crystal structures. During the template-grafting phase, the new protocol improved the fraction of accurate VL–VH orientation predictions from only 26% (12/46) to 72% (33/46) of targets. After the full RosettaAntibody protocol, including CDR H3 remodeling and VL–VH re-orientation, the new protocol produced more candidate structures with accurate VL–VH orientation than the standard protocol in 43/46 targets (93%). The improved ability to predict VL–VH orientation will bolster predictions of other parts of the paratope, including the conformation of CDR H3, a grand challenge of antibody homology modeling. PMID:27276984

  1. Target dependence of orientation and direction selectivity of corticocortical projection neurons in the mouse V1

    PubMed Central

    Matsui, Teppei; Ohki, Kenichi

    2013-01-01

    Higher order visual areas that receive input from the primary visual cortex (V1) are specialized for the processing of distinct features of visual information. However, it is still incompletely understood how this functional specialization is acquired. Here we used in vivo two photon calcium imaging in the mouse visual cortex to investigate whether this functional distinction exists at as early as the level of projections from V1 to two higher order visual areas, AL and LM. Specifically, we examined whether sharpness of orientation and direction selectivity and optimal spatial and temporal frequency of projection neurons from V1 to higher order visual areas match with that of target areas. We found that the V1 input to higher order visual areas were indeed functionally distinct: AL preferentially received inputs from V1 that were more orientation and direction selective and tuned for lower spatial frequency compared to projection of V1 to LM, consistent with functional differences between AL and LM. The present findings suggest that selective projections from V1 to higher order visual areas initiates parallel processing of sensory information in the visual cortical network. PMID:24068987

  2. On the rules of integration of crowded orientation signals.

    PubMed

    Põder, Endel

    2012-01-01

    Crowding is related to an integration of feature signals over an inappropriately large area in the visual periphery. The rules of this integration are still not well understood. This study attempts to understand how the orientation signals from the target and flankers are combined. A target Gabor, together with 2, 4, or 6 flanking Gabors, was briefly presented in a peripheral location (4° eccentricity). The observer's task was to identify the orientation of the target (eight-alternative forced-choice). Performance was found to be nonmonotonically dependent on the target-flanker orientation difference (a drop at intermediate differences). For small target-flanker differences, a strong assimilation bias was observed. An effect of the number of flankers was found for heterogeneous flankers only. It appears that different rules of integration are used, dependent on some salient aspects (target pop-out, homogeneity-heterogeneity) of the stimulus pattern. The strategy of combining simple rules may be explained by the goal of the visual system to encode potentially important aspects of a stimulus with limited processing resources and using statistical regularities of the natural visual environment.

  3. Soldier-relevant body borne load impacts minimum foot clearance during obstacle negotiation.

    PubMed

    Brown, T N; Loverro, K L; Schiffman, J M

    2016-07-01

    Soldiers often trip and fall on duty, resulting in injury. This study examined ten male soldiers' ability to negotiate an obstacle. Participants had lead and trail foot minimum foot clearance (MFC) parameters quantified while crossing a low (305 mm) and high (457 mm) obstacle with (19.4 kg) and without (6 kg) body borne load. To minimize tripping risk, participants increased lead foot MFC (p = 0.028) and reduced lead (p = 0.044) and trail (p = 0.035) foot variability when negotiating an obstacle with body borne load. While obstacle height had no effect on MFC (p = 0.273 and p = 0.126), placing the trail foot closer to the high obstacle when crossing with body borne load, resulted in greater lead (R = 0.640, b = 0.241, p = 0.046) and trail (R = 0.636, b = 0.287, p = 0.048) MFC. Soldiers, when carrying typical military loads, may be able to minimize their risk of tripping over an obstacle by creating a safety margin via greater foot clearance with reduced variability. Published by Elsevier Ltd.

  4. Forest value orientations in Australia: an application of computer content analysis

    Treesearch

    Trevor J. Webb; David N. Bengston; David P. Fan

    2008-01-01

    This article explores the expression of three forest value orientations that emerged from an analysis of Australian news media discourse about the management of Australian native forests from August 1, 1997 through December 31, 2004. Computer-coded content analysis was used to measure and track the relative importance of commodity, ecological and moral/spiritual/...

  5. "How We Stay Together Without Going Crazy:" Reconstruction of Reality Among Women of Mixed-Orientation Relationships.

    PubMed

    Adler, Adir; Ben-Ari, Adital

    2018-01-01

    Until recently, the literature that addressed the phenomenon of mixed-orientation relationships, in which the female partner is straight and the male partner is non-straight, has focused mainly on the men's perspective. Most of the studies have employed a pessimistic tone, underscoring the obstacles faced by each of the partners. This study was designed to understand how women of mixed-orientation relationships construct their reality within such a relationship, focusing on elements that assist them in maintaining those relationships. Based on the phenomenological paradigm, in-depth interviews with eight women in mixed-orientation relationships were conducted. The findings indicate that in order to adapt to their newly constructed reality, women reframe various individual, marital, and social aspects in their lives. Those reframing processes constituted a point of departure to developing a conceptual model, which outlines the journey to reality reconstruction among women in mixed-orientation relationships.

  6. Subtle perceptions of male sexual orientation influence occupational opportunities.

    PubMed

    Rule, Nicholas O; Bjornsdottir, R Thora; Tskhay, Konstantin O; Ambady, Nalini

    2016-12-01

    Theories linking the literatures on stereotyping and human resource management have proposed that individuals may enjoy greater success obtaining jobs congruent with stereotypes about their social categories or traits. Here, we explored such effects for a detectable, but not obvious, social group distinction: male sexual orientation. Bridging previous work on prejudice and occupational success with that on social perception, we found that perceivers rated gay and straight men as more suited to professions consistent with stereotypes about their groups (nurses, pediatricians, and English teachers vs. engineers, managers, surgeons, and math teachers) from mere photos of their faces. Notably, distinct evaluations of the gay and straight men emerged based on perceptions of their faces with no explicit indication of sexual orientation. Neither perceivers' expertise with hiring decisions nor diagnostic information about the targets eliminated these biases, but encouraging fair decisions did contribute to partly ameliorating the differences. Mediation analysis further showed that perceptions of the targets' sexual orientations and facial affect accounted for these effects. Individuals may therefore infer characteristics about individuals' group memberships from their faces and use this information in a way that meaningfully influences evaluations of their suitability for particular jobs. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  7. Diversity-Oriented Synthesis as a Strategy for Fragment Evolution against GSK3β.

    PubMed

    Wang, Yikai; Wach, Jean-Yves; Sheehan, Patrick; Zhong, Cheng; Zhan, Chenyang; Harris, Richard; Almo, Steven C; Bishop, Joshua; Haggarty, Stephen J; Ramek, Alexander; Berry, Kayla N; O'Herin, Conor; Koehler, Angela N; Hung, Alvin W; Young, Damian W

    2016-09-08

    Traditional fragment-based drug discovery (FBDD) relies heavily on structural analysis of the hits bound to their targets. Herein, we present a complementary approach based on diversity-oriented synthesis (DOS). A DOS-based fragment collection was able to produce initial hit compounds against the target GSK3β, allow the systematic synthesis of related fragment analogues to explore fragment-level structure-activity relationship, and finally lead to the synthesis of a more potent compound.

  8. Effects of buried obstacles on penetration resistance in cohesionless soils

    NASA Technical Reports Server (NTRS)

    Deluca, E. W.; Carrasco, L. H.

    1972-01-01

    Recent experiments concerning penetration of cohesionless soils in special molds that include solid obstacles embedded within the soil matrix are reported. The relative effects of these obstacles with respect to the soil properties of relative density, texture, and gradation are also discussed. Because lunar soil is fairly cohesionless, special attention was given to the Apollo lunar simulant, AP-12.

  9. Online optimal obstacle avoidance for rotary-wing autonomous unmanned aerial vehicles

    NASA Astrophysics Data System (ADS)

    Kang, Keeryun

    This thesis presents an integrated framework for online obstacle avoidance of rotary-wing unmanned aerial vehicles (UAVs), which can provide UAVs an obstacle field navigation capability in a partially or completely unknown obstacle-rich environment. The framework is composed of a LIDAR interface, a local obstacle grid generation, a receding horizon (RH) trajectory optimizer, a global shortest path search algorithm, and a climb rate limit detection logic. The key feature of the framework is the use of an optimization-based trajectory generation in which the obstacle avoidance problem is formulated as a nonlinear trajectory optimization problem with state and input constraints over the finite range of the sensor. This local trajectory optimization is combined with a global path search algorithm which provides a useful initial guess to the nonlinear optimization solver. Optimization is the natural process of finding the best trajectory that is dynamically feasible, safe within the vehicle's flight envelope, and collision-free at the same time. The optimal trajectory is continuously updated in real time by the numerical optimization solver, Nonlinear Trajectory Generation (NTG), which is a direct solver based on the spline approximation of trajectory for dynamically flat systems. In fact, the overall approach of this thesis to finding the optimal trajectory is similar to the model predictive control (MPC) or the receding horizon control (RHC), except that this thesis followed a two-layer design; thus, the optimal solution works as a guidance command to be followed by the controller of the vehicle. The framework is implemented in a real-time simulation environment, the Georgia Tech UAV Simulation Tool (GUST), and integrated in the onboard software of the rotary-wing UAV test-bed at Georgia Tech. Initially, the 2D vertical avoidance capability of real obstacles was tested in flight. The flight test evaluations were extended to the benchmark tests for 3D avoidance

  10. Towards an Interoperability Ontology for Software Development Tools

    DTIC Science & Technology

    2003-03-01

    The description of feature models was tied to the introduction of the Feature-Oriented Domain Analysis ( FODA *) [KANG90] approach in the late eighties...Feature-oriented domain analysis ( FODA ) is a domain analysis method developed at the Software...ese obstacles was to construct a “pilot” ontology that is extensible. We applied the Feature-Oriented Domain Analysis approach to capture the

  11. Analysis of Orientation-dependence of Martian Gullies

    NASA Technical Reports Server (NTRS)

    Mohan, S.; Bridges, N. T.

    2004-01-01

    The recent discovery of small Martian gullies has stimulated debate about the role that water plays on the Martian surface under current or recent conditions. Of critical importance in evaluating various gully hypotheses is reliable morphometric and orientation data. The former centers on such questions as whether the water (or another fluid) emanated from a surface or sub-surface source and the duration of flow. The latter ties into whether solar insolation has an important effect on formation of the initial water source and subsequent mobilization. Initial studies of gullies indicated a poleward orientation dependence, an observation which has recently been challenged. Herein we investigate the orientation of Martian gullies and the dependence of various parameters on the orientation. Whereas previous studies have been global or through most of the southern hemisphere, we focus on several specific regions. This approach offers some advantages in that regional variations are factored out, such that of lithology, ground water table depth (if any), surface thermal properties, and other parameters are more or less the same in a given region. Differences in gully attributes as a function of orientation within a region can more easily be attributable to solar insolation effects than is the case for global statistics. We use the orientation to constrain several classes of gully formation hypotheses. 1) A favored orientation toward the pole across all regions could indicate a process dominated by melting of cold trapped ice, snow, or condensed volatiles from incident sunlight during summer under current conditions. 2) Variations among all regions would be more consistent with mechanisms less strongly tied to current solar insolation, such as geothermal heating of ice. 3) Favored orientations within specific regions, but differing among regions, could indicate a preference for poleward ices and melting, with orientation being a function of age and dependent on variations

  12. Object-oriented productivity metrics

    NASA Technical Reports Server (NTRS)

    Connell, John L.; Eller, Nancy

    1992-01-01

    Software productivity metrics are useful for sizing and costing proposed software and for measuring development productivity. Estimating and measuring source lines of code (SLOC) has proven to be a bad idea because it encourages writing more lines of code and using lower level languages. Function Point Analysis is an improved software metric system, but it is not compatible with newer rapid prototyping and object-oriented approaches to software development. A process is presented here for counting object-oriented effort points, based on a preliminary object-oriented analysis. It is proposed that this approach is compatible with object-oriented analysis, design, programming, and rapid prototyping. Statistics gathered on actual projects are presented to validate the approach.

  13. Testing all six person-oriented principles in dynamic factor analysis.

    PubMed

    Molenaar, Peter C M

    2010-05-01

    All six person-oriented principles identified by Sterba and Bauer's Keynote Article can be tested by means of dynamic factor analysis in its current form. In particular, it is shown how complex interactions and interindividual differences/intraindividual change can be tested in this way. In addition, the necessity to use single-subject methods in the analysis of developmental processes is emphasized, and attention is drawn to the possibility to optimally treat developmental psychopathology by means of new computational techniques that can be integrated with dynamic factor analysis.

  14. What does recovery mean in practice? A qualitative analysis of international recovery-oriented practice guidance.

    PubMed

    Le Boutillier, Clair; Leamy, Mary; Bird, Victoria J; Davidson, Larry; Williams, Julie; Slade, Mike

    2011-12-01

    Recovery is a multifaceted concept, and the need for operationalization in practice has been identified. Although guidance on recovery-oriented practice exists, it is from disparate sources and is difficult to apply. The aims of the study were to identify the key characteristics of recovery-oriented practice guidance on the basis of current international perspectives and to develop an overarching conceptual framework to aid the translation of recovery guidance into practice. A qualitative analysis of 30 international documents offering recovery-oriented practice guidance was conducted. Inductive, semantic-level, thematic analysis was used to identify dominant themes. Interpretive analysis was then undertaken to group the themes into practice domains. The guidance documents were diverse; from six countries-the United States, England, Scotland, Republic of Ireland, Denmark, and New Zealand-and varied in document type, categories of guidance, and level of service user involvement in guidance development. The emerging conceptual framework consists of 16 dominant themes, grouped into four practice domains: promoting citizenship, organizational commitment, supporting personally defined recovery, and working relationship. A key challenge for mental health services is the lack of clarity about what constitutes recovery-oriented practice. The conceptual framework contributes to this knowledge gap and provides a synthesis of recovery-oriented practice guidance.

  15. Explosion hazards of LPG-air mixtures in vented enclosure with obstacles.

    PubMed

    Zhang, Qi; Wang, Yaxing; Lian, Zhen

    2017-07-15

    Numerical simulations were performed to study explosion characteristics of liquefied petroleum gas (LPG) explosion in enclosure with a vent. Unlike explosion overpressure and dynamic pressure, explosion temperature of the LPG-air mixture at a given concentration in a vented enclosure has very little variation with obstacle numbers for a given blockage ratio. For an enclosure without obstacle, explosion overpressures for the stoichiometric mixtures and the fuel-lean mixtures reach their maximum within the vent and that for fuel-rich mixture reaches its maximum beyond and near the vent. Dynamic pressures produced by an indoor LPG explosion reach their maximum always beyond the vent no matter obstacles are present or not in the enclosure. A LPG explosion in a vented enclosure with built-in obstacles is strong enough to make the brick and mortar wall with a thickness of 370mm damaged. If there is no obstacle in the enclosure, the lower explosion pressure of several kPa can not break the brick and mortar wall with a thickness of 370mm. For a LPG explosion produced in an enclosure with a vent, main hazards, within the vent, are overpressure and high temperature. However main hazards are dynamic pressure, blast wind, and high temperature beyond the vent. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. How does visual manipulation affect obstacle avoidance strategies used by athletes?

    PubMed

    Bijman, M P; Fisher, J J; Vallis, L A

    2016-01-01

    Research examining our ability to avoid obstacles in our path has stressed the importance of visual input. The aim of this study was to determine if athletes playing varsity-level field sports, who rely on visual input to guide motor behaviour, are more able to guide their foot over obstacles compared to recreational individuals. While wearing kinematic markers, eight varsity athletes and eight age-matched controls (aged 18-25) walked along a walkway and stepped over stationary obstacles (180° motion arc). Visual input was manipulated using PLATO visual goggles three or two steps pre-obstacle crossing and compared to trials where vision was given throughout. A main effect between groups for peak trail toe elevation was shown with greater values generated by the controls for all crossing conditions during full vision trials only. This may be interpreted as athletes not perceiving this obstacle as an increased threat to their postural stability. Collectively, findings suggest the athletic group is able to transfer their abilities to non-specific conditions during full vision trials; however, varsity-level athletes were equally reliant on visual cues for these visually guided stepping tasks as their performance was similar to the controls when vision is removed.

  17. Unifying Approach to Analytical Chemistry and Chemical Analysis: Problem-Oriented Role of Chemical Analysis.

    ERIC Educational Resources Information Center

    Pardue, Harry L.; Woo, Jannie

    1984-01-01

    Proposes an approach to teaching analytical chemistry and chemical analysis in which a problem to be resolved is the focus of a course. Indicates that this problem-oriented approach is intended to complement detailed discussions of fundamental and applied aspects of chemical determinations and not replace such discussions. (JN)

  18. C1,1 regularity for degenerate elliptic obstacle problems

    NASA Astrophysics Data System (ADS)

    Daskalopoulos, Panagiota; Feehan, Paul M. N.

    2016-03-01

    The Heston stochastic volatility process is a degenerate diffusion process where the degeneracy in the diffusion coefficient is proportional to the square root of the distance to the boundary of the half-plane. The generator of this process with killing, called the elliptic Heston operator, is a second-order, degenerate-elliptic partial differential operator, where the degeneracy in the operator symbol is proportional to the distance to the boundary of the half-plane. In mathematical finance, solutions to the obstacle problem for the elliptic Heston operator correspond to value functions for perpetual American-style options on the underlying asset. With the aid of weighted Sobolev spaces and weighted Hölder spaces, we establish the optimal C 1 , 1 regularity (up to the boundary of the half-plane) for solutions to obstacle problems for the elliptic Heston operator when the obstacle functions are sufficiently smooth.

  19. Predicate Oriented Pattern Analysis for Biomedical Knowledge Discovery

    PubMed Central

    Shen, Feichen; Liu, Hongfang; Sohn, Sunghwan; Larson, David W.; Lee, Yugyung

    2017-01-01

    In the current biomedical data movement, numerous efforts have been made to convert and normalize a large number of traditional structured and unstructured data (e.g., EHRs, reports) to semi-structured data (e.g., RDF, OWL). With the increasing number of semi-structured data coming into the biomedical community, data integration and knowledge discovery from heterogeneous domains become important research problem. In the application level, detection of related concepts among medical ontologies is an important goal of life science research. It is more crucial to figure out how different concepts are related within a single ontology or across multiple ontologies by analysing predicates in different knowledge bases. However, the world today is one of information explosion, and it is extremely difficult for biomedical researchers to find existing or potential predicates to perform linking among cross domain concepts without any support from schema pattern analysis. Therefore, there is a need for a mechanism to do predicate oriented pattern analysis to partition heterogeneous ontologies into closer small topics and do query generation to discover cross domain knowledge from each topic. In this paper, we present such a model that predicates oriented pattern analysis based on their close relationship and generates a similarity matrix. Based on this similarity matrix, we apply an innovated unsupervised learning algorithm to partition large data sets into smaller and closer topics and generate meaningful queries to fully discover knowledge over a set of interlinked data sources. We have implemented a prototype system named BmQGen and evaluate the proposed model with colorectal surgical cohort from the Mayo Clinic. PMID:28983419

  20. Cortical neurons of bats respond best to echoes from nearest targets when listening to natural biosonar multi-echo streams.

    PubMed

    Beetz, M Jerome; Hechavarría, Julio C; Kössl, Manfred

    2016-10-27

    Bats orientate in darkness by listening to echoes from their biosonar calls, a behaviour known as echolocation. Recent studies showed that cortical neurons respond in a highly selective manner when stimulated with natural echolocation sequences that contain echoes from single targets. However, it remains unknown how cortical neurons process echolocation sequences containing echo information from multiple objects. In the present study, we used echolocation sequences containing echoes from three, two or one object separated in the space depth as stimuli to study neuronal activity in the bat auditory cortex. Neuronal activity was recorded with multi-electrode arrays placed in the dorsal auditory cortex, where neurons tuned to target-distance are found. Our results show that target-distance encoding neurons are mostly selective to echoes coming from the closest object, and that the representation of echo information from distant objects is selectively suppressed. This suppression extends over a large part of the dorsal auditory cortex and may override possible parallel processing of multiple objects. The presented data suggest that global cortical suppression might establish a cortical "default mode" that allows selectively focusing on close obstacle even without active attention from the animals.

  1. Cortical neurons of bats respond best to echoes from nearest targets when listening to natural biosonar multi-echo streams

    PubMed Central

    Beetz, M. Jerome; Hechavarría, Julio C.; Kössl, Manfred

    2016-01-01

    Bats orientate in darkness by listening to echoes from their biosonar calls, a behaviour known as echolocation. Recent studies showed that cortical neurons respond in a highly selective manner when stimulated with natural echolocation sequences that contain echoes from single targets. However, it remains unknown how cortical neurons process echolocation sequences containing echo information from multiple objects. In the present study, we used echolocation sequences containing echoes from three, two or one object separated in the space depth as stimuli to study neuronal activity in the bat auditory cortex. Neuronal activity was recorded with multi-electrode arrays placed in the dorsal auditory cortex, where neurons tuned to target-distance are found. Our results show that target-distance encoding neurons are mostly selective to echoes coming from the closest object, and that the representation of echo information from distant objects is selectively suppressed. This suppression extends over a large part of the dorsal auditory cortex and may override possible parallel processing of multiple objects. The presented data suggest that global cortical suppression might establish a cortical “default mode” that allows selectively focusing on close obstacle even without active attention from the animals. PMID:27786252

  2. Perceptual learning selectively refines orientation representations in early visual cortex.

    PubMed

    Jehee, Janneke F M; Ling, Sam; Swisher, Jascha D; van Bergen, Ruben S; Tong, Frank

    2012-11-21

    Although practice has long been known to improve perceptual performance, the neural basis of this improvement in humans remains unclear. Using fMRI in conjunction with a novel signal detection-based analysis, we show that extensive practice selectively enhances the neural representation of trained orientations in the human visual cortex. Twelve observers practiced discriminating small changes in the orientation of a laterally presented grating over 20 or more daily 1 h training sessions. Training on average led to a twofold improvement in discrimination sensitivity, specific to the trained orientation and the trained location, with minimal improvement found for untrained orthogonal orientations or for orientations presented in the untrained hemifield. We measured the strength of orientation-selective responses in individual voxels in early visual areas (V1-V4) using signal detection measures, both before and after training. Although the overall amplitude of the BOLD response was no greater after training, practice nonetheless specifically enhanced the neural representation of the trained orientation at the trained location. This training-specific enhancement of orientation-selective responses was observed in the primary visual cortex (V1) as well as higher extrastriate visual areas V2-V4, and moreover, reliably predicted individual differences in the behavioral effects of perceptual learning. These results demonstrate that extensive training can lead to targeted functional reorganization of the human visual cortex, refining the cortical representation of behaviorally relevant information.

  3. Monte Carlo simulations of protein micropatterning in biomembranes: effects of immobile sticky obstacles

    NASA Astrophysics Data System (ADS)

    Arnold, Andreas M.; Sevcsik, Eva; Schütz, Gerhard J.

    2016-09-01

    Single molecule trajectories of lipids and proteins can yield valuable information about the nanoscopic organization of the plasma membrane itself. The interpretation of such trajectories, however, is complicated, as the mobility of molecules can be affected by the presence of immobile obstacles, and the transient binding of the tracers to these obstacles. We have previously developed a micropatterning approach that allows for immobilizing a plasma membrane protein and probing the diffusional behavior of a putative interaction partner in living cells. Here, we provide guidelines on how this micropatterning approach can be extended to quantify interaction parameters between plasma membrane constituents in their natural environment. We simulated a patterned membrane system and evaluated the effect of different surface densities of patterned immobile obstacles on the relative mobility as well as the surface density of diffusing tracers. In the case of inert obstacles, the size of the obstacle can be assessed from its surface density at the percolation threshold, which in turn can be extracted from the diffusion behavior of the tracer. For sticky obstacles, 2D dissociation constants can be determined from the tracer diffusion or surface density.

  4. The effects of situational obstacles and social support on suicide- prevention gatekeeper behaviors.

    PubMed

    Moore, J Taylor; Cigularov, Konstantin P; Chen, Peter Y; Martinez, Jeremy M; Hindman, Jarrod

    2011-01-01

    Although the effectiveness of suicide-prevention gatekeeper-training programs in improving knowledge, attitudes, and referral practices has been documented, their effects do not seem to be lasting. This study investigated situational obstacles at work that prevent suicide-prevention gatekeepers from engaging in suicide-prevention behavior and the role of social support in modifying the relationship between situational obstacles and suicide-prevention behaviors. 193 gatekeepers completed an online survey to rate the obstacles they had experienced at work since completing a gatekeeper-training program and the support received from coworkers, supervisors, and the organization. Participants also reported the frequency of suicide-prevention behaviors performed. The results indicated that both situational obstacles and social support predicted the number of suicide-prevention behaviors performed, as expected. There was also a trend that support from supervisors and the organization may alleviate the adverse effect of situational obstacles on suicide-prevention behavior. The cross-sectional nature of the study does not allow for directional, causal conclusions to be drawn. By understanding the roles of situational obstacles faced by trained gatekeepers at their work and the support they receive from supervisors and organizations, appropriate strategies can be identified and applied to facilitate gatekeeper performance.

  5. Overcoming an Obstacle in Expanding a UMLS Semantic Type Extent

    PubMed Central

    Chen, Yan; Gu, Huanying; Perl, Yehoshua; Geller, James

    2011-01-01

    This paper strives to overcome a major problem encountered by a previous expansion methodology for discovering concepts highly likely to be missing a specific semantic type assignment in the UMLS. This methodology is the basis for an algorithm that presents the discovered concepts to a human auditor for review and possible correction. We analyzed the problem of the previous expansion methodology and discovered that it was due to an obstacle constituted by one or more concepts assigned the UMLS Semantic Network semantic type Classification. A new methodology was designed that bypasses such an obstacle without a combinatorial explosion in the number of concepts presented to the human auditor for review. The new expansion methodology with obstacle avoidance was tested with the semantic type Experimental Model of Disease and found over 500 concepts missed by the previous methodology that are in need of this semantic type assignment. Furthermore, other semantic types suffering from the same major problem were discovered, indicating that the methodology is of more general applicability. The algorithmic discovery of concepts that are likely missing a semantic type assignment is possible even in the face of obstacles, without an explosion in the number of processed concepts. PMID:21925287

  6. Anomalous diffusion due to hindering by mobile obstacles undergoing Brownian motion or Orstein-Ulhenbeck processes.

    PubMed

    Berry, Hugues; Chaté, Hugues

    2014-02-01

    In vivo measurements of the passive movements of biomolecules or vesicles in cells consistently report "anomalous diffusion," where mean-squared displacements scale as a power law of time with exponent α<1 (subdiffusion). While the detailed mechanisms causing such behaviors are not always elucidated, movement hindrance by obstacles is often invoked. However, our understanding of how hindered diffusion leads to subdiffusion is based on diffusion amidst randomly located immobile obstacles. Here, we have used Monte Carlo simulations to investigate transient subdiffusion due to mobile obstacles with various modes of mobility. Our simulations confirm that the anomalous regimes rapidly disappear when the obstacles move by Brownian motion. By contrast, mobile obstacles with more confined displacements, e.g., Orstein-Ulhenbeck motion, are shown to preserve subdiffusive regimes. The mean-squared displacement of tracked protein displays convincing power laws with anomalous exponent α that varies with the density of Orstein-Ulhenbeck (OU) obstacles or the relaxation time scale of the OU process. In particular, some of the values we observed are significantly below the universal value predicted for immobile obstacles in two dimensions. Therefore, our results show that subdiffusion due to mobile obstacles with OU type of motion may account for the large variation range exhibited by experimental measurements in living cells and may explain that some experimental estimates are below the universal value predicted for immobile obstacles.

  7. Diversity-Oriented Synthesis as a Strategy for Fragment Evolution against GSK3β

    PubMed Central

    2016-01-01

    Traditional fragment-based drug discovery (FBDD) relies heavily on structural analysis of the hits bound to their targets. Herein, we present a complementary approach based on diversity-oriented synthesis (DOS). A DOS-based fragment collection was able to produce initial hit compounds against the target GSK3β, allow the systematic synthesis of related fragment analogues to explore fragment-level structure–activity relationship, and finally lead to the synthesis of a more potent compound. PMID:27660690

  8. Political Obstacles to Regionalization of the SUS: perceptions of Municipal Health Secretaries with seat in the Bipartite Interagency Commissions.

    PubMed

    Moreira, Marcelo Rasga; Ribeiro, José Mendes; Ouverney, Assis Mafort

    2017-04-01

    This paper aims to identify and analyze the political obstacles to the implementation of Organizational Contract of Public Action (COAP) based on the perceptions of municipal health secretaries of Bipartite Interagency Commissions (CIB). For this purpose, we interviewed 195 secretaries (92% of the total) from October 2015 to August 2016. Based on the approach of policy analysis, the main hurdles identified were, in short, a traditional obstacle (lack of resources), one that has been gaining strength in recent years (judicialization of politics) and another, perhaps unheard of: the party-political system and the State Executive Branch are the great absentees in the coalitions in support of SUS regionalization policies. We can conclude that such obstacles indicate an extremely negative setting for the implementation of the COAP and other SUS regionalization policies. Thus, it is incumbent upon those involved to reflect, negotiate and build consensus on improving the health of the population and overcome such obstacles if, of course, they embrace the authors' concept that regionalization is fundamental for the SUS.

  9. Atmospheric dispersion of a heavier-than-air gas near a two-dimensional obstacle

    NASA Astrophysics Data System (ADS)

    Sutton, S. B.; Brandt, H.; White, B. R.

    1986-04-01

    Flow over a two-dimensional obstacle and dispersion of a heavier-than-air gas near the obstacle were studied. Two species, one representing air and the other representing the heavier-than-air gas were treated. Equations for mass and momentum were cast in mass-averaged form, with turbulent Reynolds stresses and mass fluxes modeled using eddy-viscosity and diffusivity hypotheses. A two-equation k-ɛ turbulence model was used to determine the effective turbulent viscosity. Streamline curvature and buoyancy corrections were added to the basic turbulence formulation. The model equations were solved using finite difference techniques. An alternating-direction-implicit (ADI) technique was used to solve the parabolic transport equations and a direct matrix solver was used to solve the elliptic pressure equation. Mesh sensitivities were investigated to determine the optimum mesh requirements for the final calculations. It was concluded that at least 10 grid spaces were required across the obstacle width and 15 across the obstacle height to obtain valid solutions. A non-uniform mesh was used to concentrate the grid points at the top of the obstacle. Experimental measurements were made with air flow over a 7.6 by 7.6 cm obstacle in a boundary-layer wind tunnel. Smoke visualization revealed a low-frequency oscillation of the bubble downstream of the obstacle. Hot-wire anemometer data are presented for the mean velocity and turbulent kinetic energy at the mid-plane of the obstacle and the mid-plane of the downstream recirculation bubble. A single hot-wire probe was found to be suitable for determining mean streamwise velocities with an accuracy of 11 %. The downstream recirculation bubble was unsteady and had a length range from 3 to 8 obstacle lengths. The experimental results for flow over the obstacle were compared with numerical calculations to validate the numerical solution procedure. A sensitivity study on the effect of curvature correction and variation of turbulence

  10. Meaningful Cost-Benefit Analysis for Service-Oriented Architecture Projects

    DTIC Science & Technology

    2010-05-01

    SOA to identify these activities and shows how those costs come to be commingled with other development and maintenance activities. The paper argues...affected by SOA . To be consistent with the separation suggested above, this paper suggests the following new activities: • Enterprise architecture...Government or Federal Rights License 14. ABSTRACT This paper argues that proper cost-benefit analysis of service-oriented architecture projects is not

  11. A Novel mRNA Level Subtraction Method for Quick Identification of Target-Orientated Uniquely Expressed Genes Between Peanut Immature Pod and Leaf

    PubMed Central

    2010-01-01

    Subtraction technique has been broadly applied for target gene discovery. However, most current protocols apply relative differential subtraction and result in great amount clone mixtures of unique and differentially expressed genes. This makes it more difficult to identify unique or target-orientated expressed genes. In this study, we developed a novel method for subtraction at mRNA level by integrating magnetic particle technology into driver preparation and tester–driver hybridization to facilitate uniquely expressed gene discovery between peanut immature pod and leaf through a single round subtraction. The resulting target clones were further validated through polymerase chain reaction screening using peanut immature pod and leaf cDNA libraries as templates. This study has resulted in identifying several genes expressed uniquely in immature peanut pod. These target genes can be used for future peanut functional genome and genetic engineering research. PMID:21406066

  12. Improved obstacle avoidance and navigation for an autonomous ground vehicle

    NASA Astrophysics Data System (ADS)

    Giri, Binod; Cho, Hyunsu; Williams, Benjamin C.; Tann, Hokchhay; Shakya, Bicky; Bharam, Vishal; Ahlgren, David J.

    2015-01-01

    This paper presents improvements made to the intelligence algorithms employed on Q, an autonomous ground vehicle, for the 2014 Intelligent Ground Vehicle Competition (IGVC). In 2012, the IGVC committee combined the formerly separate autonomous and navigation challenges into a single AUT-NAV challenge. In this new challenge, the vehicle is required to navigate through a grassy obstacle course and stay within the course boundaries (a lane of two white painted lines) that guide it toward a given GPS waypoint. Once the vehicle reaches this waypoint, it enters an open course where it is required to navigate to another GPS waypoint while avoiding obstacles. After reaching the final waypoint, the vehicle is required to traverse another obstacle course before completing the run. Q uses modular parallel software architecture in which image processing, navigation, and sensor control algorithms run concurrently. A tuned navigation algorithm allows Q to smoothly maneuver through obstacle fields. For the 2014 competition, most revisions occurred in the vision system, which detects white lines and informs the navigation component. Barrel obstacles of various colors presented a new challenge for image processing: the previous color plane extraction algorithm would not suffice. To overcome this difficulty, laser range sensor data were overlaid on visual data. Q also participates in the Joint Architecture for Unmanned Systems (JAUS) challenge at IGVC. For 2014, significant updates were implemented: the JAUS component accepted a greater variety of messages and showed better compliance to the JAUS technical standard. With these improvements, Q secured second place in the JAUS competition.

  13. Topographic Independent Component Analysis reveals random scrambling of orientation in visual space

    PubMed Central

    Martinez-Garcia, Marina; Martinez, Luis M.

    2017-01-01

    Neurons at primary visual cortex (V1) in humans and other species are edge filters organized in orientation maps. In these maps, neurons with similar orientation preference are clustered together in iso-orientation domains. These maps have two fundamental properties: (1) retinotopy, i.e. correspondence between displacements at the image space and displacements at the cortical surface, and (2) a trade-off between good coverage of the visual field with all orientations and continuity of iso-orientation domains in the cortical space. There is an active debate on the origin of these locally continuous maps. While most of the existing descriptions take purely geometric/mechanistic approaches which disregard the network function, a clear exception to this trend in the literature is the original approach of Hyvärinen and Hoyer based on infomax and Topographic Independent Component Analysis (TICA). Although TICA successfully addresses a number of other properties of V1 simple and complex cells, in this work we question the validity of the orientation maps obtained from TICA. We argue that the maps predicted by TICA can be analyzed in the retinal space, and when doing so, it is apparent that they lack the required continuity and retinotopy. Here we show that in the orientation maps reported in the TICA literature it is easy to find examples of violation of the continuity between similarly tuned mechanisms in the retinal space, which suggest a random scrambling incompatible with the maps in primates. The new experiments in the retinal space presented here confirm this guess: TICA basis vectors actually follow a random salt-and-pepper organization back in the image space. Therefore, the interesting clusters found in the TICA topology cannot be interpreted as the actual cortical orientation maps found in cats, primates or humans. In conclusion, Topographic ICA does not reproduce cortical orientation maps. PMID:28640816

  14. Topographic Independent Component Analysis reveals random scrambling of orientation in visual space.

    PubMed

    Martinez-Garcia, Marina; Martinez, Luis M; Malo, Jesús

    2017-01-01

    Neurons at primary visual cortex (V1) in humans and other species are edge filters organized in orientation maps. In these maps, neurons with similar orientation preference are clustered together in iso-orientation domains. These maps have two fundamental properties: (1) retinotopy, i.e. correspondence between displacements at the image space and displacements at the cortical surface, and (2) a trade-off between good coverage of the visual field with all orientations and continuity of iso-orientation domains in the cortical space. There is an active debate on the origin of these locally continuous maps. While most of the existing descriptions take purely geometric/mechanistic approaches which disregard the network function, a clear exception to this trend in the literature is the original approach of Hyvärinen and Hoyer based on infomax and Topographic Independent Component Analysis (TICA). Although TICA successfully addresses a number of other properties of V1 simple and complex cells, in this work we question the validity of the orientation maps obtained from TICA. We argue that the maps predicted by TICA can be analyzed in the retinal space, and when doing so, it is apparent that they lack the required continuity and retinotopy. Here we show that in the orientation maps reported in the TICA literature it is easy to find examples of violation of the continuity between similarly tuned mechanisms in the retinal space, which suggest a random scrambling incompatible with the maps in primates. The new experiments in the retinal space presented here confirm this guess: TICA basis vectors actually follow a random salt-and-pepper organization back in the image space. Therefore, the interesting clusters found in the TICA topology cannot be interpreted as the actual cortical orientation maps found in cats, primates or humans. In conclusion, Topographic ICA does not reproduce cortical orientation maps.

  15. Enceladus Jet Orientations: Effects of Surface Structure

    NASA Astrophysics Data System (ADS)

    Helfenstein, P.; Porco, C.; DiNino, D.

    2013-12-01

    Jetting activity across the South Polar Terrain (SPT) of Enceladus is now known to erupt directly from tiger-stripe rifts and associated fracture systems. However, details of the vent conduit geometry are hidden below the icy surface. The three-dimensional orientations of the erupting jets may provide important clues. Porco et al. (2013, Lunar Planet. Sci. Conf. 44th, p.1775) surveyed jet locations and orientations as imaged at high resolution (< 1.3 km/pixel) by Cassini ISS from 2005 through May 2012. Ninety-eight (98) jets were identified either on the main trunks or branches of the 4 tiger-stripes. The azimuth angles of the jets are seen to vary across the SPT. Here, we use histogram analysis of the survey data to test if the jet azimuths are influenced by their placement relative to surface morphology and tectonic structures. Azimuths are measured positive counterclockwise with zero pointing along the fracture in the direction of the sub-Saturn hemisphere, and rosette histograms were binned in 30° increments. Overall, the jet azimuths are not random and only about 11% of them are co-aligned with the tiger stripe valley. There are preferred diagonal orientations between 105°-165° and again between 255°-345°. These trends are dominant along the Damascus and Baghdad tiger-stripes where more than half of the jets are found. Histograms for Cairo and Alexandria show less-distinct trends, fewer jets being measured there, but combining data from both suggests a different pattern of preferred orientations; from 45°-75° and 265°-280°. Many possible factors could affect the orientations of jets, for example, the conduit shape, the presence of obstacles like narrow medial ridges called 'shark-fins' along tiger-stripe valleys, the possibility that jets may breach the surface at some point other than the center of a tiger-stripe, and the presence of structural fabrics or mechanical weaknesses, such as patterns of cross-cutting fractures. The dominance of diagonally

  16. Effect of cane length and swing arc width on drop-off and obstacle detection with the long cane

    PubMed Central

    Kim, Dae Shik; Emerson, Robert Wall; Naghshineh, Koorosh

    2017-01-01

    A repeated-measures design with block randomization was used for the study, in which 15 adults with visual impairments attempted to detect the drop-offs and obstacles with the canes of different lengths, swinging the cane in different widths (narrow vs wide). Participants detected the drop-offs significantly more reliably with the standard-length cane (79.5% ± 6.5% of the time) than with the extended-length cane (67.6% ± 9.1%), p <.001. The drop-off detection threshold of the standard-length cane (4.1 ± 1.1 cm) was also significantly smaller than that of the extended-length cane (6.5±1.8cm), p <.001. In addition, participants detected drop-offs at a significantly higher percentage when they swung the cane approximately 3 cm beyond the widest part of the body (78.6% ± 7.6%) than when they swung it substantially wider (30 cm; 68.5% ± 8.3%), p <.001. In contrast, neither cane length (p =.074) nor cane swing arc width (p =.185) had a significant effect on obstacle detection performance. The findings of the study may help orientation and mobility specialists recommend appropriate cane length and cane swing arc width to visually impaired cane users. PMID:29276326

  17. Effect of cane length and swing arc width on drop-off and obstacle detection with the long cane.

    PubMed

    Kim, Dae Shik; Emerson, Robert Wall; Naghshineh, Koorosh

    2017-09-01

    A repeated-measures design with block randomization was used for the study, in which 15 adults with visual impairments attempted to detect the drop-offs and obstacles with the canes of different lengths, swinging the cane in different widths (narrow vs wide). Participants detected the drop-offs significantly more reliably with the standard-length cane (79.5% ± 6.5% of the time) than with the extended-length cane (67.6% ± 9.1%), p <.001. The drop-off detection threshold of the standard-length cane (4.1 ± 1.1 cm) was also significantly smaller than that of the extended-length cane (6.5±1.8cm), p <.001. In addition, participants detected drop-offs at a significantly higher percentage when they swung the cane approximately 3 cm beyond the widest part of the body (78.6% ± 7.6%) than when they swung it substantially wider (30 cm; 68.5% ± 8.3%), p <.001. In contrast, neither cane length ( p =.074) nor cane swing arc width ( p =.185) had a significant effect on obstacle detection performance. The findings of the study may help orientation and mobility specialists recommend appropriate cane length and cane swing arc width to visually impaired cane users.

  18. Obstacle Detection in Indoor Environment for Visually Impaired Using Mobile Camera

    NASA Astrophysics Data System (ADS)

    Rahman, Samiur; Ullah, Sana; Ullah, Sehat

    2018-01-01

    Obstacle detection can improve the mobility as well as the safety of visually impaired people. In this paper, we present a system using mobile camera for visually impaired people. The proposed algorithm works in indoor environment and it uses a very simple technique of using few pre-stored floor images. In indoor environment all unique floor types are considered and a single image is stored for each unique floor type. These floor images are considered as reference images. The algorithm acquires an input image frame and then a region of interest is selected and is scanned for obstacle using pre-stored floor images. The algorithm compares the present frame and the next frame and compute mean square error of the two frames. If mean square error is less than a threshold value α then it means that there is no obstacle in the next frame. If mean square error is greater than α then there are two possibilities; either there is an obstacle or the floor type is changed. In order to check if the floor is changed, the algorithm computes mean square error of next frame and all stored floor types. If minimum of mean square error is less than a threshold value α then flour is changed otherwise there exist an obstacle. The proposed algorithm works in real-time and 96% accuracy has been achieved.

  19. 76 FR 52239 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-22

    ... Minimums & Obstacle DP, Orig-A Red Oak, IA, Red Oak Muni, Takeoff Minimums & Obstacle DP, Amdt 3 Storm Lake, IA, Storm Lake Muni, Takeoff Minimums & Obstacle DP, Orig Dwight, IL, Dwight, Takeoff Minimums..., Florence Rgnl, RNAV (GPS) RWY 9, Orig-A Spearfish, SD, Black Hills-Clydes Ice Field, RNAV (GPS) RWY 13...

  20. Towards an organisation-wide process-oriented organisation of care: A literature review

    PubMed Central

    2011-01-01

    Background Many hospitals have taken actions to make care delivery for specific patient groups more process-oriented, but struggle with the question how to deal with process orientation at hospital level. The aim of this study is to report and discuss the experiences of hospitals with implementing process-oriented organisation designs in order to derive lessons for future transitions and research. Methods A literature review of English language articles on organisation-wide process-oriented redesigns, published between January 1998 and May 2009, was performed. Results Of 329 abstracts identified, 10 articles were included in the study. These articles described process-oriented redesigns of five hospitals. Four hospitals tried to become process-oriented by the implementation of coordination measures, and one by organisational restructuring. The adoption of the coordination mechanism approach was particularly constrained by the functional structure of hospitals. Other factors that hampered the redesigns in general were the limited applicability of and unfamiliarity with process improvement techniques. Conclusions Due to the limitations of the evidence, it is not known which approach, implementation of coordination measures or organisational restructuring (with additional coordination measures), produces the best results in which situation. Therefore, more research is needed. For this research, the use of qualitative methods in addition to quantitative measures is recommended to contribute to a better understanding of preconditions and contingencies for an effective application of approaches to become process-oriented. Hospitals are advised to take the factors for failure described into account and to take suitable actions to counteract these obstacles on their way to become process-oriented organisations. PMID:21247491

  1. Towards an organisation-wide process-oriented organisation of care: a literature review.

    PubMed

    Vos, Leti; Chalmers, Sarah E; Dückers, Michel La; Groenewegen, Peter P; Wagner, Cordula; van Merode, Godefridus G

    2011-01-19

    Many hospitals have taken actions to make care delivery for specific patient groups more process-oriented, but struggle with the question how to deal with process orientation at hospital level. The aim of this study is to report and discuss the experiences of hospitals with implementing process-oriented organisation designs in order to derive lessons for future transitions and research. A literature review of English language articles on organisation-wide process-oriented redesigns, published between January 1998 and May 2009, was performed. Of 329 abstracts identified, 10 articles were included in the study. These articles described process-oriented redesigns of five hospitals. Four hospitals tried to become process-oriented by the implementation of coordination measures, and one by organisational restructuring. The adoption of the coordination mechanism approach was particularly constrained by the functional structure of hospitals. Other factors that hampered the redesigns in general were the limited applicability of and unfamiliarity with process improvement techniques. Due to the limitations of the evidence, it is not known which approach, implementation of coordination measures or organisational restructuring (with additional coordination measures), produces the best results in which situation. Therefore, more research is needed. For this research, the use of qualitative methods in addition to quantitative measures is recommended to contribute to a better understanding of preconditions and contingencies for an effective application of approaches to become process-oriented. Hospitals are advised to take the factors for failure described into account and to take suitable actions to counteract these obstacles on their way to become process-oriented organisations.

  2. The effects of paradigmatic orientations of education research and discourse

    NASA Astrophysics Data System (ADS)

    Smithson, John Lawrence

    This essay presents an examination of contemporary disputes over methodological and epistemological foundations underlying inquiry within the field of education research; investigating the obstacles to communication and understanding found in scholarly exchanges occurring across competing paradigmatic orientations. Terminological challenges to cross-paradigmatic communication are examined, identifying three specific terminological difficulties, referred to as homonym, contextual, and onti-stemic problems. Nicholas Burbules' model of dialogue, based upon characteristics of convergence, divergence, inclusive and critical traits, is adopted and applied to a sample of cross-paradigmatic exchanges found in recent educational research journals. Examination of those exchanges reveals certain strategies associated with cross-paradigmatic communication. These strategies, labeled as trivialization, caricaturization, and re-direction, are shown to be detrimental to the mutual understanding of the interlocutors. The model is then extended to address examples of paradigmatic orientations within methodological and epistemological contexts in order to consider the relationship between the various orientations represented in the literature of interest. Methodological and epistemological orientations are shown to be loosely coupled, with unexpected shifts in paradigmatic values found among researchers' methodological and epistemological commitments. Finally, the nature of the relationship between competing paradigmatic orientations is examined, with particular attention given to four types of incommensurability (ontological, linguistic, epistemological, and values incommensurability). I conclude that, though difficult, cross-paradigmatic communication is necessary in order to provide a multi-paradigmatic perspective that takes us beyond the fractured picture of educational phenomena available from current research approaches.

  3. Obstacles to Scientific Research in Light of a Number of Variables

    ERIC Educational Resources Information Center

    Algadheeb, Nourah A.; Almeqren, Monira A.

    2014-01-01

    The present study aimed to identify the scientific research obstacles facing faculty members in the College of Education at Princess Nora bint Abdul Rahman University (PNU) and to determine the differences in the obstacles according to age, academic rank, scientific specialty, marital status, number of completed studies, and time since the last…

  4. Effect of visuospatial neglect on spatial navigation and heading after stroke.

    PubMed

    Aravind, Gayatri; Lamontagne, Anouk

    2017-06-09

    Visuospatial neglect (VSN) impairs the control of locomotor heading in post-stroke individuals, which may affect their ability to safely avoid moving objects while walking. We aimed to compare VSN+ and VSN- stroke individuals in terms of changes in heading and head orientation in space while avoiding obstacles approaching from different directions and reorienting toward the final target. Stroke participants with VSN (VSN+) and without VSN (VSN-) walked in a virtual environment avoiding obstacles that approached contralesionally, head-on or ipsilesionally. Measures of obstacle avoidance (onset-of-heading change, maximum mediolateral deviation) and target alignment (heading and head-rotation errors with respect to target) were compared across groups and obstacle directions. In total, 26 participants with right-hemisphere stroke participated (13 VSN+ and 13 VSN-; 24 males; mean age 60.3 years, range 48 to 72 years). A larger proportion of VSN+ (75%) than VSN- (38%) participants collided with contralesional and head-on obstacles. For VSN- participants, deviating to the same side as the obstacle was a safe strategy to avoid diagonal obstacles and deviating to the opposite-side led to occasional collisions. VSN+ participants deviated ipsilesionally, displaying same-side and opposite-side strategies for ipsilesional and contralesional obstacles, respectively. Overall, VSN+ participants showed greater distances at onset-of-heading change, smaller maximum mediolateral deviation and larger errors in target alignment as compared with VSN- participants. The ipsilesional bias arising from VSN influences the modulation of heading in response to obstacles and, along with the adoption of the "riskier" strategies, contribute to the higher number colliders and poor goal-directed walking abilities in stroke survivors with VSN. Future research should focus on developing assessment and training tools for complex locomotor tasks such as obstacle avoidance in this population. Copyright

  5. Obstacles to engaging in young driver licensing: Perspectives of parents.

    PubMed

    Naz, Sehana; Scott-Parker, Bridie

    2017-02-01

    Young novice drivers remain at greater risk of injury and death despite a wealth of interventions including graduated driver licensing (GDL) programs. The key to implementing safer practices inherent in GDL appears to lie with optimising the role of parents. This qualitative research explored the parent's perspectives of obstacles to engaging in the driver licensing process within a GDL program. Parents also shared advice on what they found helpful, and where relevant, recommended changes in the process to enable safer practices for young drivers. Twenty-three parents (aged 35-60 years, M=49.52, SD=8.01, 11 males) participated in semi-structured interviews regarding licensing experiences with their young driver children. The young drivers included learner (n=11), provisional (restricted/intermediate) (n=9) and open (unrestricted/full) licence drivers (n=3), ranging from 16 to 24 years (M=18.04, SD=2.21, 13 males). Content analysis revealed that most obstacles were encountered at the learner licensing phase, with the parent-reported difficult temperament of the learner driver the most prominent. Unsurprisingly, advice to other parents to be patient and remain calm featured heavily during the same phase. Anxiety from not having control of the vehicle was another obstacle at the learner phase, translating to anxieties for child safety in the early stages of provisional driving. Recommendations for the current GDL included more rigorous road rule testing, with general support for the program, professional driver training at learner and provisional stages facilitated parental engagement through the licensing phases. The findings overwhelmingly suggest a need for parents to be educated regarding their importance in, and of, the driver licensing process, and the efficacy of their instruction, content and practices. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Effect of obstacle position in the flow of sheep through a narrow door.

    PubMed

    Zuriguel, Iker; Olivares, Jorge; Pastor, José M; Martín-Gómez, César; Ferrer, Luis M; Ramos, Juan J; Garcimartín, Angel

    2016-09-01

    In a recent work [Phys. Rev. E 91, 022808 (2015)PLEEE81539-375510.1103/PhysRevE.91.022808] it was reported that placing an obstacle in front of a gate has a beneficial effect in the flow of sheep through it. Here, we extend such results by implementing three different obstacle positions. We have observed that the flow is improved in two cases, while it worsens in the other one; the last instance happens when the obstacle is too close to the door. In this situation, the outcomes suggest that clogging develops between the doorjamb and the obstacle, contrary to the cases when the obstacle is farther, in which case clogging always occurs at the very door. The effectiveness of the obstacle (a strategy put forward to alleviate clogging in emergency exits) is therefore quite sensitive to its location. In addition, the study of the temporal evolution of the flow rate as the test develops makes evident a steady behavior during the entire duration of the entrance. This result is at odds with recent findings in human evacuation tests where the flow rate varies over time, therefore challenging the fairness of straightforward comparisons between pedestrian behavior and animal experimental observations.

  7. Stability of gas channels in a dense suspension in the presence of obstacles

    NASA Astrophysics Data System (ADS)

    Poryles, Raphaël; Varas, Germán; Vidal, Valérie

    2017-06-01

    We investigate experimentally the influence of a fixed obstacle on gas rising in a dense suspension. Air is injected at a constant flow rate by a single nozzle at the bottom center of a Hele-Shaw cell. Without obstacles, previous works have shown that a fluidized zone is formed with a parabolic shape, with a central air channel and two granular convection rolls on its sides. Here, we quantify the influence of the obstacle's shape, size, and height on the location and dynamics of the central air channel. Different regimes are reported: the air channel can simply deviate (stable), or it can switch sides over time (unstable), leading to two signatures not only above the obstacle, but sometimes also below it. This feedback also influences the channel deviation when bypassing the obstacle. A wake of less or no motion is reported above the largest obstacles as well as the maximum probability of gas location, which can be interesting for practical applications. The existence of a critical height hc≃7 cm is discussed and compared with the existence of an air finger that develops from the injection nozzle and is stable in time. A dimensionless number describing the transition between air fingering and fracturing makes it possible to predict the channel's stability.

  8. Object-oriented requirements analysis: A quick tour

    NASA Technical Reports Server (NTRS)

    Berard, Edward V.

    1990-01-01

    Of all the approaches to software development, an object-oriented approach appears to be both the most beneficial and the most popular. The description of the object-oriented approach is presented in the form of the view graphs.

  9. Strategies for handling ethical problems in end of life care: obstacles and possibilities.

    PubMed

    Rejnö, Åsa; Berg, Linda

    2015-11-01

    In end of life care, ethical problems often come to the fore. Little research is performed on ways or strategies for handling those problems and even less on obstacles to and possibilities of using such strategies. A previous study illuminated stroke team members' experiences of ethical problems and how the teams managed the situation when caring for patients faced with sudden and unexpected death from stroke. These findings have been further explored in this study. The aim of the study was to illuminate obstacles and possibilities perceived by stroke team members in using strategies for handling ethical problems when caring for patients afflicted by sudden and unexpected death caused by stroke. A qualitative method with combined deductive and inductive content analysis was utilized. Data were collected through individual interviews with 15 stroke team members working in stroke units of two associated county hospitals in western Sweden. The study was approved by the Regional Ethics Review Board, Gothenburg, Sweden. Permission was also obtained from the director of each stroke unit. All the studied strategies for handling of ethical problems were found to have both obstacles and possibilities. Uncertainty is shown as a major obstacle and unanimity as a possibility in the use of the strategies. The findings also illuminate the value of the concept "the patient's best interests" as a starting point for the carers' ethical reasoning. The concept "the patient's best interests" used as a starting point for ethical reasoning among the carers is not explicitly defined yet, which might make this value difficult to use both as a universal concept and as an argument for decisions. Carers therefore need to strengthen their argumentation and reflect on and use ethically grounded arguments and defined ethical values like dignity in their clinical work and decisions. © The Author(s) 2014.

  10. Obstacles of Teaching Mathematics Faced by the Class Teachers in Jordan

    ERIC Educational Resources Information Center

    Nejem, Khamis Mousa; Muhanna, Waffa

    2013-01-01

    The purpose of the study is to investigate the obstacles of teaching mathematics faced by the class teachers in Jordan. To achieve this purpose a study sample of 192 male and female class teachers was selected randomly from government schools. The instrument of the study was a questionnaire used to investigate the obstacles of mathematics…

  11. Obstacle stepping involves spinal anticipatory activity associated with quadrupedal limb coordination.

    PubMed

    Michel, J; van Hedel, H J A; Dietz, V

    2008-04-01

    Obstacle avoidance steps are associated with a facilitation of spinal reflexes in leg muscles. Here we have examined the involvement of both leg and arm muscles. Subjects walking with reduced vision on a treadmill were acoustically informed about an approaching obstacle and received feedback about task performance. Reflex responses evoked by tibial nerve stimulation were observed in all arm and leg muscles examined in this study. They were enhanced before the execution of obstacle avoidance compared with normal steps and showed an exponential adaptation in contralateral arm flexor muscles corresponding to the improvement of task performance. This enhancement was absent when the body was partially supported during the task. During the execution of obstacle steps, electromyographic activity in the arm muscles mimicked the preceding reflex behaviour with respect to enhancement and adaptation. Our results demonstrate an anticipatory quadrupedal limb coordination with an involvement of proximal arm muscles in the acquisition and performance of this precision locomotor task. This is presumably achieved by an up-regulated activity of coupled cervico-thoracal interneuronal circuits.

  12. An orientation analysis method for protein immobilized on quantum dot particles

    NASA Astrophysics Data System (ADS)

    Aoyagi, Satoka; Inoue, Masae

    2009-11-01

    The evaluation of orientation of biomolecules immobilized on nanodevices is crucial for the development of high performance devices. Such analysis requires ultra high sensitivity so as to be able to detect less than one molecular layer on a device. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) has sufficient sensitivity to evaluate the uppermost surface structure of a single molecular layer. The objective of this study is to develop an orientation analysis method for proteins immobilized on nanomaterials such as quantum dot particles, and to evaluate the orientation of streptavidin immobilized on quantum dot particles by means of TOF-SIMS. In order to detect fragment ions specific to the protein surface, a monoatomic primary ion source (Ga +) and a cluster ion source (Au 3+) were employed. Streptavidin-immobilized quantum dot particles were immobilized on aminosilanized ITO glass plates at amino groups by covalent bonding. The reference samples streptavidin directly immobilized on ITO plates were also prepared. All samples were dried with a freeze dryer before TOF-SIMS measurement. The positive secondary ion spectra of each sample were obtained using TOF-SIMS with Ga + and Au 3+, respectively, and then they were compared so as to characterize each sample and detect the surface structure of the streptavidin immobilized with the biotin-immobilized quantum dots. The chemical structures of the upper surface of the streptavidin molecules immobilized on the quantum dot particles were evaluated with TOF-SIMS spectra analysis. The indicated surface side of the streptavidin molecules immobilized on the quantum dots includes the biotin binding site.

  13. Flow through a very porous obstacle in a shallow channel.

    PubMed

    Creed, M J; Draper, S; Nishino, T; Borthwick, A G L

    2017-04-01

    A theoretical model, informed by numerical simulations based on the shallow water equations, is developed to predict the flow passing through and around a uniform porous obstacle in a shallow channel, where background friction is important. This problem is relevant to a number of practical situations, including flow through aquatic vegetation, the performance of arrays of turbines in tidal channels and hydrodynamic forces on offshore structures. To demonstrate this relevance, the theoretical model is used to (i) reinterpret core flow velocities in existing laboratory-based data for an array of emergent cylinders in shallow water emulating aquatic vegetation and (ii) reassess the optimum arrangement of tidal turbines to generate power in a tidal channel. Comparison with laboratory-based data indicates a maximum obstacle resistance (or minimum porosity) for which the present theoretical model is valid. When the obstacle resistance is above this threshold the shallow water equations do not provide an adequate representation of the flow, and the theoretical model over-predicts the core flow passing through the obstacle. The second application of the model confirms that natural bed resistance increases the power extraction potential for a partial tidal fence in a shallow channel and alters the optimum arrangement of turbines within the fence.

  14. Overcoming an obstacle in expanding a UMLS semantic type extent.

    PubMed

    Chen, Yan; Gu, Huanying; Perl, Yehoshua; Geller, James

    2012-02-01

    This paper strives to overcome a major problem encountered by a previous expansion methodology for discovering concepts highly likely to be missing a specific semantic type assignment in the UMLS. This methodology is the basis for an algorithm that presents the discovered concepts to a human auditor for review and possible correction. We analyzed the problem of the previous expansion methodology and discovered that it was due to an obstacle constituted by one or more concepts assigned the UMLS Semantic Network semantic type Classification. A new methodology was designed that bypasses such an obstacle without a combinatorial explosion in the number of concepts presented to the human auditor for review. The new expansion methodology with obstacle avoidance was tested with the semantic type Experimental Model of Disease and found over 500 concepts missed by the previous methodology that are in need of this semantic type assignment. Furthermore, other semantic types suffering from the same major problem were discovered, indicating that the methodology is of more general applicability. The algorithmic discovery of concepts that are likely missing a semantic type assignment is possible even in the face of obstacles, without an explosion in the number of processed concepts. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Flow through a very porous obstacle in a shallow channel

    PubMed Central

    Draper, S.; Nishino, T.; Borthwick, A. G. L.

    2017-01-01

    A theoretical model, informed by numerical simulations based on the shallow water equations, is developed to predict the flow passing through and around a uniform porous obstacle in a shallow channel, where background friction is important. This problem is relevant to a number of practical situations, including flow through aquatic vegetation, the performance of arrays of turbines in tidal channels and hydrodynamic forces on offshore structures. To demonstrate this relevance, the theoretical model is used to (i) reinterpret core flow velocities in existing laboratory-based data for an array of emergent cylinders in shallow water emulating aquatic vegetation and (ii) reassess the optimum arrangement of tidal turbines to generate power in a tidal channel. Comparison with laboratory-based data indicates a maximum obstacle resistance (or minimum porosity) for which the present theoretical model is valid. When the obstacle resistance is above this threshold the shallow water equations do not provide an adequate representation of the flow, and the theoretical model over-predicts the core flow passing through the obstacle. The second application of the model confirms that natural bed resistance increases the power extraction potential for a partial tidal fence in a shallow channel and alters the optimum arrangement of turbines within the fence. PMID:28484321

  16. Sex and age-level differences of walking time in preschool children on an obstacle frame

    PubMed Central

    2012-01-01

    Background Stepping over an obstacle is a kind of compound movement that makes walking more difficult, especially for preschool children. This study examines sex and age-level differences in walking time in preschool children on an obstacle frame. Methods The participants included 324 healthy preschool children: four-year-old boys (51) and girls (51), five-year-old boys (50) and girls (60), and six-year-old boys (62) and girls (50). A 5 cm- or 10 cm-high obstacle (depth 11.5 cm, width 23.5 cm) was set at the halfway point of a 200 cm × 10 cm walking course. Results The participants walked to the end of the course and back as fast as possible under three conditions: no obstacle, low obstacle and high obstacle. Walking time showed age-level differences in all conditions, but there were no differences in sex. Age levels were divided into two groups, with one group within the first six months of their birthday, and the second group within the last six months of that year. Walking time for children in the first half of their fourth year was longer than that of the five- and six-year-old children. In addition, for children in the last half of their fourth year, walking time was longer than both sexes in the last half of their fifth and sixth years. The children in the latter half of their fifth year had a longer walking time in the high obstacle condition than those in the last half of their sixth year. In the four-year-old participants, walking time was shorter with no obstacles than with a high obstacle frame. Conclusions In the above data, obstacle course walking time does not show a gender difference, except that the four-year-old participants needed longer than the five- and six-year-old children. Setting the obstacle 10 cm high also produced a different walking time in the five- and six-year-old participants. The high obstacle step test (10 cm) best evaluated the dynamic balance of preschool children. PMID:22738328

  17. Fast and reliable obstacle detection and segmentation for cross-country navigation

    NASA Technical Reports Server (NTRS)

    Talukder, A.; Manduchi, R.; Rankin, A.; Matthies, L.

    2002-01-01

    Obstacle detection is one of the main components of the control system of autonomous vehicles. In the case of indoor/urban navigation, obstacles are typically defined as surface points that are higher than the ground plane. This characterization, however, cannot be used in cross-country and unstructured environments, where the notion of ground plane is often not meaningful.

  18. Featural Guidance in Conjunction Search: The Contrast between Orientation and Color

    ERIC Educational Resources Information Center

    Anderson, Giles M.; Heinke, Dietmar; Humphreys, Glyn W.

    2010-01-01

    Four experiments examined the effects of precues on visual search for targets defined by a color-orientation conjunction. Experiment 1 showed that cueing the identity of targets enhanced the efficiency of search. Cueing effects were stronger with color than with orientation cues, but this advantage was additive across array size. Experiment 2…

  19. Quantitative analysis of diffusion tensor orientation: theoretical framework.

    PubMed

    Wu, Yu-Chien; Field, Aaron S; Chung, Moo K; Badie, Benham; Alexander, Andrew L

    2004-11-01

    Diffusion-tensor MRI (DT-MRI) yields information about the magnitude, anisotropy, and orientation of water diffusion of brain tissues. Although white matter tractography and eigenvector color maps provide visually appealing displays of white matter tract organization, they do not easily lend themselves to quantitative and statistical analysis. In this study, a set of visual and quantitative tools for the investigation of tensor orientations in the human brain was developed. Visual tools included rose diagrams, which are spherical coordinate histograms of the major eigenvector directions, and 3D scatterplots of the major eigenvector angles. A scatter matrix of major eigenvector directions was used to describe the distribution of major eigenvectors in a defined anatomic region. A measure of eigenvector dispersion was developed to describe the degree of eigenvector coherence in the selected region. These tools were used to evaluate directional organization and the interhemispheric symmetry of DT-MRI data in five healthy human brains and two patients with infiltrative diseases of the white matter tracts. In normal anatomical white matter tracts, a high degree of directional coherence and interhemispheric symmetry was observed. The infiltrative diseases appeared to alter the eigenvector properties of affected white matter tracts, showing decreased eigenvector coherence and interhemispheric symmetry. This novel approach distills the rich, 3D information available from the diffusion tensor into a form that lends itself to quantitative analysis and statistical hypothesis testing. (c) 2004 Wiley-Liss, Inc.

  20. Supersonic flows past an obstacle in Yukawa liquids

    NASA Astrophysics Data System (ADS)

    Charan, Harish; Ganesh, Rajaraman

    2018-04-01

    Shock formation, when a supersonic flow passes a stationary obstacle, is ubiquitous in nature. Considering particles mediating via a Yukawa-type interaction as a prototype for a strongly coupled complex plasma, characterized by coupling strength (Γ, ratio of the average potential to kinetic energy per particle) and screening parameter (κ, ratio of the mean inter-particle distance to the shielding length), we address the fundamental problem of supersonic fluid flow U0, past a stationary obstacle immersed in this strongly coupled system. We here report the results on the bow shocks formed in Yukawa liquids when the liquid flows at speeds larger than the speed of sound in the system. Depending on the values of Mach number MC L=U/0 CL , where CL is the longitudinal speed of sound in the system, the bow shocks are found to be either traveling or localized. We find that for the transonic flows (0.8 ≲ MC L≲ 1.2), the bow shocks travel in the upstream direction opposite to the incoming fluid. The phase velocity of the traveling bow shocks is found to be a non-monotonous function of κ, varying as ∝1 /k1.11 at a fixed value of Γ, and is found to be independent of Γ at a fixed value of κ. It is observed that for the flow values with MC L>1.5 , the shock waves do not travel in the upstream direction but instead form a stationary arc like structure around the obstacle. For the fluid flows with 1 ≲ MC L≲ 2.6 , secondary bow shocks are seen to emerge behind the stationary obstacle which travel in the downstream direction, and the phase velocity of these secondary bow shocks is found to be equal to that of the primary bow shocks.

  1. Orbital navigation, docking and obstacle avoidance as a form of three dimensional model-based image understanding

    NASA Technical Reports Server (NTRS)

    Beyer, J.; Jacobus, C.; Mitchell, B.

    1987-01-01

    Range imagery from a laser scanner can be used to provide sufficient information for docking and obstacle avoidance procedures to be performed automatically. Three dimensional model-based computer vision algorithms in development can perform these tasks even with targets which may not be cooperative (that is, objects without special targets or markers to provide unambiguous location points). Roll, pitch and yaw of the vehicle can be taken into account as image scanning takes place, so that these can be corrected when the image is converted from egocentric to world coordinates. Other attributes of the sensor, such as the registered reflectence and texture channels, provide additional data sources for algorithm robustness. Temporal fusion of sensor immages can take place in the work coordinate domain, allowing for the building of complex maps in three dimensional space.

  2. Description and status update on GELLO: a proposed standardized object-oriented expression language for clinical decision support.

    PubMed

    Sordo, Margarita; Boxwala, Aziz A; Ogunyemi, Omolola; Greenes, Robert A

    2004-01-01

    A major obstacle to sharing computable clinical knowledge is the lack of a common language for specifying expressions and criteria. Such a language could be used to specify decision criteria, formulae, and constraints on data and action. Al-though the Arden Syntax addresses this problem for clinical rules, its generalization to HL7's object-oriented data model is limited. The GELLO Expression language is an object-oriented language used for expressing logical conditions and computations in the GLIF3 (GuideLine Interchange Format, v. 3) guideline modeling language. It has been further developed under the auspices of the HL7 Clinical Decision Support Technical Committee, as a proposed HL7 standard., GELLO is based on the Object Constraint Language (OCL), because it is vendor-independent, object-oriented, and side-effect-free. GELLO expects an object-oriented data model. Although choice of model is arbitrary, standardization is facilitated by ensuring that the data model is compatible with the HL7 Reference Information Model (RIM).

  3. Using object-oriented analysis to design a multi-mission ground data system

    NASA Technical Reports Server (NTRS)

    Shames, Peter

    1995-01-01

    This paper describes an analytical approach and descriptive methodology that is adapted from Object-Oriented Analysis (OOA) techniques. The technique is described and then used to communicate key issues of system logical architecture. The essence of the approach is to limit the analysis to only service objects, with the idea of providing a direct mapping from the design to a client-server implementation. Key perspectives on the system, such as user interaction, data flow and management, service interfaces, hardware configuration, and system and data integrity are covered. A significant advantage of this service-oriented approach is that it permits mapping all of these different perspectives on the system onto a single common substrate. This services substrate is readily represented diagramatically, thus making details of the overall design much more accessible.

  4. Obstacle Crossing During Gait in Children With Cerebral Palsy: Cross-Sectional Study With Kinematic Analysis of Dynamic Balance and Trunk Control.

    PubMed

    Malone, Ailish; Kiernan, Damien; French, Helen; Saunders, Valerie; O'Brien, Timothy

    2016-08-01

    Balance problems are common in children who have cerebral palsy (CP) but are active and ambulant. Control of the whole-body center of mass is critical in maintaining dynamic stability during challenging mobility tasks, such as clearing an obstacle while walking. The objective of this study was to compare trunk and lower limb kinematics and center-of-mass control in children with CP and those in children with typical development during obstacle crossing. This was a cross-sectional study. Thirty-four children who were 5 to 17 years of age (17 with CP and 17 with typical development) and matched in age and height completed 2 gait trials involving crossing a 10-cm obstacle. Three-dimensional kinematic and kinetic data were captured with a general-purpose 3-dimensional motion tracking system and forceplates. Trunk data were captured with a validated model. All children cleared the obstacle with similar hip and knee kinematics, step length, and single-support duration. In children with CP, step width was increased by 4.81 cm, and center-of-mass velocity was significantly slower at lead limb toe-off (0.31 m/s) and during lead limb clearance (0.2 m/s). Children with CP showed altered trunk and pelvis movement, characterized by significantly greater pelvic obliquity, pelvic tilt, and trunk rotation throughout the task, increased lateral trunk lean during lead limb crossing (3.7°), and greater sagittal trunk movement as the trail limb crossed (5.1°). The study was not powered to analyze differences between children with diplegia and those with hemiplegia. Children with CP required greater adjustments at the trunk and pelvis to achieve successful obstacle crossing. The increase in trunk movement could have been compensatory for reduced stability distally or for a primary problem reflecting poor proximal control. The findings suggest that rehabilitation should focus on both proximal trunk control and distal stability to improve balance. © 2016 American Physical Therapy

  5. Obstacles to action in arthritis: a community case-control study.

    PubMed

    Hutton, Ingrid; Gamble, Greg; McLean, Grant; Butcher, Hugh; Gow, Peter; Dalbeth, Nicola

    2009-07-01

    Despite the benefits of physical activity, people with arthritis are less active than the general population. The aim of this study was to determine the motivators and obstacles to physical activity for adults with arthritis. Participants were identified from the Obstacles to Action Study, a community based study of 8163 adults, which explored barriers and motivators to physical activity. A 1:1 case-control study was designed; cases were identified as those participants who reported arthritis (n = 1106). Each case was matched with an age, sex and ethnicity-matched non-arthritis control (n = 1106). Cases were less likely to achieve recommended physical activity targets (58.8% vs. 68.1% P = 0.00001). Furthermore, fewer people with arthritis believed that physical activity would help them lead healthy lives (86.7% vs. 91.3% P = 0.006) or viewed physical activity as a priority (53.8% vs. 59.8% P = 0.005). Cases were less confident in their abilities to try a new activity (37.1% vs. 43.7% P = 0.002) or maintain a healthy weight (65.0% vs. 74.3% P = 0.00001). Cases also reported greater negative impact scores for barriers to activity, particularly arthritis, accessibility, cost and discomfort while exercising. Motivators and environmental barriers to activity were similar for cases and controls. These findings persisted after adjusting for educational level, body mass index and comorbidities. People with arthritis are less active and demonstrate different attitudes toward physical activity. Although people with arthritis identify similar environmental barriers, they have different psychosocial barriers. In order to design effective physical activity programs for people with arthritis, these barriers must be specifically addressed.

  6. Perceptual Learning Selectively Refines Orientation Representations in Early Visual Cortex

    PubMed Central

    Jehee, Janneke F.M.; Ling, Sam; Swisher, Jascha D.; van Bergen, Ruben S.; Tong, Frank

    2013-01-01

    Although practice has long been known to improve perceptual performance, the neural basis of this improvement in humans remains unclear. Using fMRI in conjunction with a novel signal detection-based analysis, we show that extensive practice selectively enhances the neural representation of trained orientations in the human visual cortex. Twelve observers practiced discriminating small changes in the orientation of a laterally presented grating over 20 or more daily one-hour training sessions. Training on average led to a two-fold improvement in discrimination sensitivity, specific to the trained orientation and the trained location, with minimal improvement found for untrained orthogonal orientations or for orientations presented in the untrained hemifield. We measured the strength of orientation-selective responses in individual voxels in early visual areas (V1–V4) using signal detection measures, both pre- and post-training. Although the overall amplitude of the BOLD response was no greater after training, practice nonetheless specifically enhanced the neural representation of the trained orientation at the trained location. This training-specific enhancement of orientation-selective responses was observed in the primary visual cortex (V1) as well as higher extrastriate visual areas V2–V4, and moreover, reliably predicted individual differences in the behavioral effects of perceptual learning. These results demonstrate that extensive training can lead to targeted functional reorganization of the human visual cortex, refining the cortical representation of behaviorally relevant information. PMID:23175828

  7. On Stationary Navier-Stokes Flows Around a Rotating Obstacle in Two-Dimensions

    NASA Astrophysics Data System (ADS)

    Higaki, Mitsuo; Maekawa, Yasunori; Nakahara, Yuu

    2018-05-01

    We study the two-dimensional stationary Navier-Stokes equations describing the flows around a rotating obstacle. The unique existence of solutions and their asymptotic behavior at spatial infinity are established when the rotation speed of the obstacle and the given exterior force are sufficiently small.

  8. Residence time of symmetric random walkers in a strip with large reflective obstacles

    NASA Astrophysics Data System (ADS)

    Ciallella, Alessandro; Cirillo, Emilio N. M.; Sohier, Julien

    2018-05-01

    We study the effect of a large obstacle on the so-called residence time, i.e., the time that a particle performing a symmetric random walk in a rectangular (two-dimensional, 2D) domain needs to cross the strip. We observe complex behavior: We find out that the residence time does not depend monotonically on the geometric properties of the obstacle, such as its width, length, and position. In some cases, due to the presence of the obstacle, the mean residence time is shorter with respect to the one measured for the obstacle-free strip. We explain the residence time behavior by developing a one-dimensional (1D) analog of the 2D model where the role of the obstacle is played by two defect sites having smaller probability to be crossed with respect to all the other regular sites. The 1D and 2D models behave similarly, but in the 1D case we are able to compute exactly the residence time, finding a perfect match with the Monte Carlo simulations.

  9. Vortex shedding from obstacles: theoretical frequency prediction

    NASA Astrophysics Data System (ADS)

    Pier, Benoît

    2001-11-01

    The existence of self-sustained oscillations in spatially developing systems is closely related to the presence of a locally absolutely unstable region. A recent investigation of a ``synthetic wake'' (a wake with no solid obstacle and no reverse flow region) has proved [Pier and Huerre, J. Fluid Mech. 435, 145 (2001)] that the observed Kármán vortex street is a nonlinear elephant global mode. The same criterion is now shown to hold for real obstacles. Local properties are derived from the unperturbed basic flow computed by enforcing a symmetry condition on the central line. Application of the theoretical criterion then yields the expected Strouhal vortex shedding frequency. The thus predicted frequency is in excellent agreement with direct numerical simulations of the complete flow. The use of the frequency selection mechanism to control the vortex shedding will also be discussed.

  10. Dark soliton past a finite-size obstacle

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

    Bilas, Nicolas; Pavloff, Nicolas

    2005-09-15

    We consider the collision of a dark soliton with an obstacle in a quasi-one-dimensional Bose condensate. We show that in many respects the soliton behaves as an effective classical particle of mass twice the mass of a bare particle, evolving in an effective potential which is a convolution of the actual potential describing the obstacle. Radiative effects beyond this approximation are also taken into account. The emitted waves are shown to form two counterpropagating wave packets, both moving at the speed of sound. We determine, at leading order, the total amount of radiation emitted during the collision and compute themore » acceleration of the soliton due to the collisional process. It is found that the radiative process is quenched when the velocity of the soliton reaches the velocity of sound in the system.« less

  11. An Obstacle-Tolerant Path Planning Algorithm for Mobile-Anchor-Node-Assisted Localization

    PubMed Central

    Tsai, Rong-Guei

    2018-01-01

    The location information obtained using a sensor is a critical requirement in wireless sensor networks. Numerous localization schemes have been proposed, among which mobile-anchor-node-assisted localization (MANAL) can reduce costs and overcome environmental constraints. A mobile anchor node (MAN) provides its own location information to assist the localization of sensor nodes. Numerous path planning schemes have been proposed for MANAL, but most scenarios assume the absence of obstacles in the environment. However, in a realistic environment, sensor nodes cannot be located because the obstacles block the path traversed by the MAN, thereby rendering the sensor incapable of receiving sufficient three location information from the MAN. This study proposes the obstacle-tolerant path planning (OTPP) approach to solve the sensor location problem owing to obstacle blockage. OTPP can approximate the optimum beacon point number and path planning, thereby ensuring that all the unknown nodes can receive the three location information from the MAN and reduce the number of MAN broadcast packet times. Experimental results demonstrate that OTPP performs better than Z-curves because it reduces the total number of beacon points utilized and is thus more suitable in an obstacle-present environment. Compared to the Z-curve, OTPP can reduce localization error and improve localization coverage. PMID:29547582

  12. Binocular combination of stimulus orientation.

    PubMed

    Yehezkel, O; Ding, J; Sterkin, A; Polat, U; Levi, D M

    2016-11-01

    When two sine waves that differ slightly in orientation are presented to the two eyes separately, a single cyclopean sine wave is perceived. However, it is unclear how the brain calculates its orientation. Here, we used a signal detection rating method to estimate the perceived orientation when the two eyes were presented with Gabor patches that differed in both orientation and contrast. We found a nearly linear combination of orientation when both targets had the same contrast. However, the binocular percept shifted away from the linear prediction towards the orientation with the higher contrast, depending on both the base contrast and the contrast ratio. We found that stimuli that differ slightly in orientation are combined into a single percept, similarly for monocular and binocular presentation, with a bias that depends on the interocular contrast ratio. Our results are well fitted by gain-control models, and are consistent with a previous study that favoured the DSKL model that successfully predicts binocular phase and contrast combination and binocular contrast discrimination. In this model, the departures from linearity may be explained on the basis of mutual suppression and mutual enhancement, both of which are stronger under dichoptic than monocular conditions.

  13. Image classification independent of orientation and scale

    NASA Astrophysics Data System (ADS)

    Arsenault, Henri H.; Parent, Sebastien; Moisan, Sylvain

    1998-04-01

    The recognition of targets independently of orientation has become fairly well developed in recent years for in-plane rotation. The out-of-plane rotation problem is much less advanced. When both out-of-plane rotations and changes of scale are present, the problem becomes very difficult. In this paper we describe our research on the combined out-of- plane rotation problem and the scale invariance problem. The rotations were limited to rotations about an axis perpendicular to the line of sight. The objects to be classified were three kinds of military vehicles. The inputs used were infrared imagery and photographs. We used a variation of a method proposed by Neiberg and Casasent, where a neural network is trained with a subset of the database and a minimum distances from lines in feature space are used for classification instead of nearest neighbors. Each line in the feature space corresponds to one class of objects, and points on one line correspond to different orientations of the same target. We found that the training samples needed to be closer for some orientations than for others, and that the most difficult orientations are where the target is head-on to the observer. By means of some additional training of the neural network, we were able to achieve 100% correct classification for 360 degree rotation and a range of scales over a factor of five.

  14. Identification of Vibrotactile Patterns Encoding Obstacle Distance Information.

    PubMed

    Kim, Yeongmi; Harders, Matthias; Gassert, Roger

    2015-01-01

    Delivering distance information of nearby obstacles from sensors embedded in a white cane-in addition to the intrinsic mechanical feedback from the cane-can aid the visually impaired in ambulating independently. Haptics is a common modality for conveying such information to cane users, typically in the form of vibrotactile signals. In this context, we investigated the effect of tactile rendering methods, tactile feedback configurations and directions of tactile flow on the identification of obstacle distance. Three tactile rendering methods with temporal variation only, spatio-temporal variation and spatial/temporal/intensity variation were investigated for two vibration feedback configurations. Results showed a significant interaction between tactile rendering method and feedback configuration. Spatio-temporal variation generally resulted in high correct identification rates for both feedback configurations. In the case of the four-finger vibration, tactile rendering with spatial/temporal/intensity variation also resulted in high distance identification rate. Further, participants expressed their preference for the four-finger vibration over the single-finger vibration in a survey. Both preferred rendering methods with spatio-temporal variation and spatial/temporal/intensity variation for the four-finger vibration could convey obstacle distance information with low workload. Overall, the presented findings provide valuable insights and guidance for the design of haptic displays for electronic travel aids for the visually impaired.

  15. Orientation effects on the measurement and analysis of critical CTOA in an aluminum alloy sheet

    NASA Technical Reports Server (NTRS)

    Sutton, M. A.; Dawicke, D. S.; Newman, J. C., Jr.

    1994-01-01

    Fracture tests were conducted on 76.2mm wide, 2.3mm thick middle crack tension (M(T)) specimens machined from 2024-T3 aluminum sheet. The specimens were tested on the T-L orientation and comparisons were made to similar tests conducted in the L-T orientation. Measurement of critical crack tip opening angle (CTOA), applied stress, and crack front shape were made as a function of crack extension. A two-dimensional, elastic-plastic finite element analysis was used to simulate the fracture behavior for both orientations. The results indicate that the T-L orientation had a 10 percent lower stress at fracture than similar tests conducted in the L-T orientation. Correspondingly, the critical CTOA in the T-L tests reached a constant value of 4.7 degrees after 2-3mm of crack extension and the L-T tests reached a value of 6 degrees. The fracture surfaces of the T-L specimens were observed to remain flat, while those of the L-T specimens transitioned to a 45 degree slant fracture after about 2-3mm of crack extension. The tunneling behavior of the two orientations also differed; the T-L specimens reached a deeply tunneled stabilized crack front shape while, the L-T specimens were observed to have only a small amount of tunneling once the crack began to grow on the 45 degree slant. The two-dimensional, elastic-plastic finite element analysis was able to simulate the fracture behavior for both the T-L and L-T orientations.

  16. Insecurity in the DRC: The Obstacle to Peace and Stability

    DTIC Science & Technology

    2016-12-01

    neighboring nations since the mid-1990s. In particular, the protected presence of armed groups has been a major obstacle to peace. Based on the best...study of the DRC to analyze four DDR programs initiated in the DRC from 2002 to 2009, with the goal of better understanding why they failed. The...beginning in the mid-1990s. In particular, the protected presence of armed groups has been a major obstacle to peace. Based on the best practices

  17. Obstacles in Qualitative Research: Possible Solutions

    ERIC Educational Resources Information Center

    Poggenpoel, M.; Myburgh, C. P. H.

    2005-01-01

    In conducting research, the identified problem in the field will determine the research strategies chosen to address the problem. When a qualitative research strategy is deemed as the most appropriate strategy to get answers to research questions, the researcher should be aware of obstacles that can be encountered in the research process. If the…

  18. Water in the presence of inert Lennard-Jones obstacles

    NASA Astrophysics Data System (ADS)

    Kurtjak, Mario; Urbic, Tomaz

    2014-04-01

    Water confined by the presence of a 'sea' of inert obstacles was examined. In the article, freely mobile two-dimensional Mercedes-Benz (MB) water put to a disordered, but fixed, matrix of Lennard-Jones disks was studied by the Monte Carlo computer simulations. For the MB water molecules in the matrix of Lennard-Jones disks, we explored the structures, hydrogen-bond-network formation and thermodynamics as a function of temperature and size and density of matrix particles. We found that the structure of model water is perturbed by the presence of the obstacles. Density of confined water, which was in equilibrium with the bulk water, was smaller than the density of the bulk water and the temperature dependence of the density of absorbed water did not show the density anomaly in the studied temperature range. The behaviour observed as a consequence of confinement is similar to that of increasing temperature, which can for a matrix lead to a process similar to capillary evaporation. At the same occupancy of space, smaller matrix molecules cause higher destruction effect on the absorbed water molecules than the bigger ones. We have also tested the hypothesis that at low matrix densities the obstacles induce an increased ordering and 'hydrogen bonding' of the MB model molecules, relative to pure fluid, while at high densities the obstacles reduce MB water structuring, as they prevent the fluid to form good 'hydrogen-bonding' networks. However, for the size of matrix molecules similar to that of water, we did not observe this effect.

  19. The use of a proteinaceous "cushion" with a polystyrene-binding peptide tag to control the orientation and function of a target peptide adsorbed to a hydrophilic polystyrene surface.

    PubMed

    Imanaka, Hiroyuki; Yamadzumi, Daisuke; Yanagita, Keisuke; Ishida, Naoyuki; Nakanishi, Kazuhiro; Imamura, Koreyoshi

    2016-03-01

    In immobilizing target biomolecules on a solid surface, it is essential (i) to orient the target moiety in a preferred direction and (ii) to avoid unwanted interactions of the target moiety including with the solid surface. The preferred orientation of the target moiety can be achieved by genetic conjugation of an affinity peptide tag specific to the immobilization surface. Herein, we report on a strategy for reducing the extent of direct interaction between the target moiety and surface in the immobilization of hexahistidine peptide (6His) and green fluorescent protein (GFP) on a hydrophilic polystyrene (PS) surface: Ribonuclease HII from Thermococcus kodakaraensis (cHII) was genetically inserted as a "cushion" between the PS-affinity peptide tag and target moiety. The insertion of a cushion protein resulted in a considerably stronger immobilization of target biomolecules compared to conjugation with only a PS affinity peptide tag, resulting in a substantially enhanced accessibility of the detection antibody to the target 6His peptide. The fluorescent intensity of the GFP moiety was decreased by approximately 30% as the result of fusion with cHII and the PS-affinity peptide tag but was fully retained in the immobilization on the PS surface irrespective of the increased binding force. Furthermore, the fusion of cHII did not impair the stability of the target GFP moiety. Accordingly, the use of a proteinaceous cushion appears to be promising for the immobilization of functional biomolecules on a solid surface. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:527-534, 2016. © 2016 American Institute of Chemical Engineers.

  20. Obstacles to Disarmament Education. Centre for Peace Studies Occasional Paper No. 6.

    ERIC Educational Resources Information Center

    Reardon, Betty

    Obstacles to disarmament education fall into three general categories: political, perceptual, and pedagogical. At the elementary school level, these obstacles occur because of: (1) a lack of opportunities for cross-cultural experiences; (2) the socialization processes that enforce the belief that a child's culture is superior to and competitive…

  1. Vision-based obstacle recognition system for automated lawn mower robot development

    NASA Astrophysics Data System (ADS)

    Mohd Zin, Zalhan; Ibrahim, Ratnawati

    2011-06-01

    Digital image processing techniques (DIP) have been widely used in various types of application recently. Classification and recognition of a specific object using vision system require some challenging tasks in the field of image processing and artificial intelligence. The ability and efficiency of vision system to capture and process the images is very important for any intelligent system such as autonomous robot. This paper gives attention to the development of a vision system that could contribute to the development of an automated vision based lawn mower robot. The works involve on the implementation of DIP techniques to detect and recognize three different types of obstacles that usually exist on a football field. The focus was given on the study on different types and sizes of obstacles, the development of vision based obstacle recognition system and the evaluation of the system's performance. Image processing techniques such as image filtering, segmentation, enhancement and edge detection have been applied in the system. The results have shown that the developed system is able to detect and recognize various types of obstacles on a football field with recognition rate of more 80%.

  2. Vortex propagation around a wall-mounted obstacle in pulsatile flow

    NASA Astrophysics Data System (ADS)

    Carr, Ian A.; Plesniak, Michael W.

    2015-11-01

    Wall-mounted obstacles are prevalent in nature and engineering applications. Physiological flows observed in human vocal fold pathologies, such as polyps, can be modeled by flow over a wall-mounted protuberance. Despite their prevalence, studies of wall-mounted obstacles have been restricted to steady (constant velocity) freestream flow. In biological and geophysical applications, pulsatile flow is much more common, yet effects of pulsatility on the wake of a wall-mounted obstacle remain to be extensively studied. This study aims to characterize the complex physics produced in this unsteady, separated flow. Experiments were performed in a low-speed wind tunnel with a set of rotating vanes, which produce the pulsatile inflow waveform. Instantaneous and phase-averaged particle image velocimetry (PIV) results acquired around a hemispherical obstacle are presented and compared. A mechanism based on self-induced vortex propagation, analogous to that in vortex rings, is proposed to explain the observed dynamics of coherent structures. Predictions of the propagation velocity based on analytical expressions for vortex rings in a viscous fluid are compared to the experimentally measured propagation velocity. Effects of the unsteady boundary layer on the observed physics are explored. This material is based in part upon work supported by the National Science Foundation under Grant Number CBET-1236351, and GW Center for Biomimetics and Bioinspired Engineering (COBRE).

  3. Measures for simulator evaluation of a helicopter obstacle avoidance system

    NASA Technical Reports Server (NTRS)

    Demaio, Joe; Sharkey, Thomas J.; Kennedy, David; Hughes, Micheal; Meade, Perry

    1993-01-01

    The U.S. Army Aeroflightdynamics Directorate (AFDD) has developed a high-fidelity, full-mission simulation facility for the demonstration and evaluation of advanced helicopter mission equipment. The Crew Station Research and Development Facility (CSRDF) provides the capability to conduct one- or two-crew full-mission simulations in a state-of-the-art helicopter simulator. The CSRDF provides a realistic, full field-of-regard visual environment with simulation of state-of-the-art weapons, sensors, and flight control systems. We are using the CSRDF to evaluate the ability of an obstacle avoidance system (OASYS) to support low altitude flight in cluttered terrain using night vision goggles (NVG). The OASYS uses a laser radar to locate obstacles to safe flight in the aircraft's flight path. A major concern is the detection of wires, which can be difficult to see with NVG, but other obstacles--such as trees, poles or the ground--are also a concern. The OASYS symbology is presented to the pilot on a head-up display mounted on the NVG (NVG-HUD). The NVG-HUD presents head-stabilized symbology to the pilot while allowing him to view the image intensified, out-the-window scene through the HUD. Since interference with viewing through the display is a major concern, OASYS symbology must be designed to present usable obstacle clearance information with a minimum of clutter.

  4. The use of image analysis in evaluation of the fibers orientation in Wood-polymer composites (WPC)

    NASA Astrophysics Data System (ADS)

    Bednarz, Arkadiusz; Frącz, Wiesław; Janowski, Grzegorz

    2016-12-01

    In this paper a novel way of a digital analysis of fibers orientation with a five-step algorithmwas presented. In the study, a molded piece with a dumbbell shape prepared from wood-polymer composite was used. The injection molding process was examined in experimental and numerical way. Based on the developed mathematical algorithm, a significant compliance of fiber orientation in different areas of the molded piece was obtained. The main aim of thisworkwas fiber orientation analysis of wood-polymer composites. An additional goal of thiswork was the comparison of the results reached in numerical analysis with results obtained from an experiment. The results of this research were important for the scientific and also from the practical point of view. In future works the prepared algorithm could be used to reach optimal parameters of the injection molding process.

  5. Neural correlates of obstacle negotiation in older adults: An fNIRS study.

    PubMed

    Chen, Michelle; Pillemer, Sarah; England, Sarah; Izzetoglu, Meltem; Mahoney, Jeannette R; Holtzer, Roee

    2017-10-01

    Older adults are less efficient at avoiding obstacles compared to young adults, especially under attention-demanding conditions. Using functional near-infrared-spectroscopy (fNIRS), recent studies implicated the prefrontal cortex (PFC) in cognitive control of locomotion, notably under dual-task walking conditions. The neural substrates underlying Obstacle Negotiation (ON), however, have not been established. The current study determined the role of the PFC in ON during walking in seniors. Non-demented older adults (n=90; mean age=78.1±5.5years; %female=51) underwent fNIRS acquisition to assess changes in hemodynamic activity in the PFC during normal-walk [NW] and walk-while-talk [WWT] conditions with and without obstacles. Obstacles were presented as red elliptical shapes using advanced laser technology, which resemble potholes. Linear mixed effects models were used to determine differences in oxygenated hemoglobin (HbO 2 ) levels among the four task conditions. The presence of slow gait, a risk factor for dementia and falls, served as a predictor hypothesized to moderate the effect of obstacles on PFC HbO 2 levels. PFC HbO 2 levels were significantly higher in WWT compared to NW (p<0.001) irrespective of ON. Slow gait moderated the effect of obstacles on HbO 2 levels across task conditions. Specifically, compared to participants with normal gait, PFC HbO 2 levels were significantly increased in ON-NW relative to NW (p=0.017) and ON-WWT relative to WWT (p<0.001) among individuals with slow gait. Consistent with Compensatory Reallocation, ON required greater PFC involvement among individuals with mobility limitations. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. The quality of visual information about the lower extremities influences visuomotor coordination during virtual obstacle negotiation.

    PubMed

    Kim, Aram; Kretch, Kari S; Zhou, Zixuan; Finley, James M

    2018-05-09

    Successful negotiation of obstacles during walking relies on the integration of visual information about the environment with ongoing locomotor commands. When information about the body and environment are removed through occlusion of the lower visual field, individuals increase downward head pitch angle, reduce foot placement precision, and increase safety margins during crossing. However, whether these effects are mediated by loss of visual information about the lower extremities, the obstacle, or both remains to be seen. Here, we used a fully immersive, virtual obstacle negotiation task to investigate how visual information about the lower extremities is integrated with information about the environment to facilitate skillful obstacle negotiation. Participants stepped over virtual obstacles while walking on a treadmill with one of three types of visual feedback about the lower extremities: no feedback, end-point feedback, or a link-segment model. We found that absence of visual information about the lower extremities led to an increase in the variability of leading foot placement after crossing. The presence of a visual representation of the lower extremities promoted greater downward head pitch angle during the approach to and subsequent crossing of an obstacle. In addition, having greater downward head pitch was associated with closer placement of the trailing foot to the obstacle, further placement of the leading foot after the obstacle, and higher trailing foot clearance. These results demonstrate that the fidelity of visual information about the lower extremities influences both feed-forward and feedback aspects of visuomotor coordination during obstacle negotiation.

  7. The addition of stripes (a version of the 'horizontal-vertical illusion') increases foot clearance when crossing low-height obstacles.

    PubMed

    Foster, Richard J; Buckley, John G; Whitaker, David; Elliott, David B

    2016-07-01

    Trips over obstacles are one of the main causes of falling in older adults, with vision playing an important role in successful obstacle negotiation. We determined whether a horizontal-vertical illusion, superimposed onto low-height obstacles to create a perceived increase in obstacle height, increased foot clearances during obstacle negotiation thus reducing the likelihood of tripping. Eleven adults (mean ± 1 SD: age 27.3 ± 5.1 years) negotiated obstacles of varying heights (3, 5, 7 cm) with four different appearance conditions; two were obstacles with a horizontal-vertical illusion (vertical stripes of different thickness) superimposed on the front, one was a plain obstacle and the fourth a plain obstacle with a horizontal black line painted on the top edge. Foot clearance parameters were compared across conditions. Both illusions led to a significant increase in foot clearance when crossing the obstacle, compared to the plain condition, irrespective of obstacle height. Superimposing a horizontal-vertical illusion onto low-height obstacles can increase foot clearance, and its use on the floor section of a double-glazing door frame for example may reduce the incidence of tripping in the home. Practitioner Summary: Low-height obstacles such as the floor section of a double-glazing door frame are potential tripping hazards. In a gait lab-based study we found that a horizontal-vertical illusion superimposed onto low-height obstacles led to significantly higher foot clearances; indicating their potential as a useful safety measure.

  8. Statistical properties of gravity-driven granular discharge flow under the influence of an obstacle

    NASA Astrophysics Data System (ADS)

    Endo, Keita; Katsuragi, Hiroaki

    2017-06-01

    Two-dimensional granular discharge flow driven by gravity under the influence of an obstacle is experimentally investigated. A horizontal exit of width W is opened at the bottom of vertical Hele-Shaw cell filled with stainless-steel particles to start the discharge flow. In this experiment, a circular obstacle is placed in front of the exit. Thus, the distance between the exit and obstacle L is also an important parameter. During the discharge, granular-flow state is acquired by a high-speed camera. The bulk discharge-flow rate is also measured by load cell sensors. The obtained high-speed-image data are analyzed to clarify the particle-level granular-flow dynamics. Using the measured data, we find that the obstacle above the exit affects the granular- flow field. Specifically, the existence of obstacle results in large horizontal granular temperature and small packing fraction. This tendency becomes significant when L is smaller than approximately 6Dg when W ≃ 4Dg, where Dg is diameter of particles.

  9. EMEN2: An Object Oriented Database and Electronic Lab Notebook

    PubMed Central

    Rees, Ian; Langley, Ed; Chiu, Wah; Ludtke, Steven J.

    2013-01-01

    Transmission electron microscopy and associated methods such as single particle analysis, 2-D crystallography, helical reconstruction and tomography, are highly data-intensive experimental sciences, which also have substantial variability in experimental technique. Object-oriented databases present an attractive alternative to traditional relational databases for situations where the experiments themselves are continually evolving. We present EMEN2, an easy to use object-oriented database with a highly flexible infrastructure originally targeted for transmission electron microscopy and tomography, which has been extended to be adaptable for use in virtually any experimental science. It is a pure object-oriented database designed for easy adoption in diverse laboratory environments, and does not require professional database administration. It includes a full featured, dynamic web interface in addition to APIs for programmatic access. EMEN2 installations currently support roughly 800 scientists worldwide with over 1/2 million experimental records and over 20 TB of experimental data. The software is freely available with complete source. PMID:23360752

  10. A Study on the Difficulties of Learning Phase Transition in Object-Oriented Analysis and Design from the Viewpoint of Semantic Distance

    ERIC Educational Resources Information Center

    Shin, Shin-Shing

    2015-01-01

    Students in object-oriented analysis and design (OOAD) courses typically encounter difficulties transitioning from object-oriented analysis (OOA) to logical design (OOLD). This study conducted an empirical experiment to examine these learning difficulties by evaluating differences between OOA-to-OOLD and OOLD-to-object-oriented-physical-design…

  11. Short range laser obstacle detector. [for surface vehicles using laser diode array

    NASA Technical Reports Server (NTRS)

    Kuriger, W. L. (Inventor)

    1973-01-01

    A short range obstacle detector for surface vehicles is described which utilizes an array of laser diodes. The diodes operate one at a time, with one diode for each adjacent azimuth sector. A vibrating mirror a short distance above the surface provides continuous scanning in elevation for all azimuth sectors. A diode laser is synchronized with the vibrating mirror to enable one diode laser to be fired, by pulses from a clock pulse source, a number of times during each elevation scan cycle. The time for a given pulse of light to be reflected from an obstacle and received is detected as a measure of range to the obstacle.

  12. Collaborative Learning Practices: Teacher and Student Perceived Obstacles to Effective Student Collaboration

    ERIC Educational Resources Information Center

    Le, Ha; Janssen, Jeroen; Wubbels, Theo

    2018-01-01

    While the educational literature mentions several obstacles affecting the effectiveness of collaborative learning (CL), they have often been investigated through the perceptions of only one actor, either teachers or students. Therefore, some sources of obstacles that teachers and students encounter may not have been revealed. In this study, 19…

  13. Meanline Analysis of Turbines with Choked Flow in the Object-Oriented Turbomachinery Analysis Code

    NASA Technical Reports Server (NTRS)

    Hendricks, Eric S.

    2016-01-01

    The prediction of turbomachinery performance characteristics is an important part of the conceptual aircraft engine design process. During this phase, the designer must examine the effects of a large number of turbomachinery design parameters to determine their impact on overall engine performance and weight. The lack of detailed design information available in this phase necessitates the use of simpler meanline and streamline methods to determine the turbomachinery geometry characteristics and provide performance estimates prior to more detailed CFD (Computational Fluid Dynamics) analyses. While a number of analysis codes have been developed for this purpose, most are written in outdated software languages and may be difficult or impossible to apply to new, unconventional designs. The Object-Oriented Turbomachinery Analysis Code (OTAC) is currently being developed at NASA Glenn Research Center to provide a flexible meanline and streamline analysis capability in a modern object-oriented language. During the development and validation of OTAC, a limitation was identified in the code's ability to analyze and converge turbines as the flow approached choking. This paper describes a series of changes which can be made to typical OTAC turbine meanline models to enable the assessment of choked flow up to limit load conditions. Results produced with this revised model setup are provided in the form of turbine performance maps and are compared to published maps.

  14. psRNATarget: a plant small RNA target analysis server

    PubMed Central

    Dai, Xinbin; Zhao, Patrick Xuechun

    2011-01-01

    Plant endogenous non-coding short small RNAs (20–24 nt), including microRNAs (miRNAs) and a subset of small interfering RNAs (ta-siRNAs), play important role in gene expression regulatory networks (GRNs). For example, many transcription factors and development-related genes have been reported as targets of these regulatory small RNAs. Although a number of miRNA target prediction algorithms and programs have been developed, most of them were designed for animal miRNAs which are significantly different from plant miRNAs in the target recognition process. These differences demand the development of separate plant miRNA (and ta-siRNA) target analysis tool(s). We present psRNATarget, a plant small RNA target analysis server, which features two important analysis functions: (i) reverse complementary matching between small RNA and target transcript using a proven scoring schema, and (ii) target-site accessibility evaluation by calculating unpaired energy (UPE) required to ‘open’ secondary structure around small RNA’s target site on mRNA. The psRNATarget incorporates recent discoveries in plant miRNA target recognition, e.g. it distinguishes translational and post-transcriptional inhibition, and it reports the number of small RNA/target site pairs that may affect small RNA binding activity to target transcript. The psRNATarget server is designed for high-throughput analysis of next-generation data with an efficient distributed computing back-end pipeline that runs on a Linux cluster. The server front-end integrates three simplified user-friendly interfaces to accept user-submitted or preloaded small RNAs and transcript sequences; and outputs a comprehensive list of small RNA/target pairs along with the online tools for batch downloading, key word searching and results sorting. The psRNATarget server is freely available at http://plantgrn.noble.org/psRNATarget/. PMID:21622958

  15. Obstacle Detection and Avoidance System Based on Monocular Camera and Size Expansion Algorithm for UAVs

    PubMed Central

    Al-Kaff, Abdulla; García, Fernando; Martín, David; De La Escalera, Arturo; Armingol, José María

    2017-01-01

    One of the most challenging problems in the domain of autonomous aerial vehicles is the designing of a robust real-time obstacle detection and avoidance system. This problem is complex, especially for the micro and small aerial vehicles, that is due to the Size, Weight and Power (SWaP) constraints. Therefore, using lightweight sensors (i.e., Digital camera) can be the best choice comparing with other sensors; such as laser or radar.For real-time applications, different works are based on stereo cameras in order to obtain a 3D model of the obstacles, or to estimate their depth. Instead, in this paper, a method that mimics the human behavior of detecting the collision state of the approaching obstacles using monocular camera is proposed. The key of the proposed algorithm is to analyze the size changes of the detected feature points, combined with the expansion ratios of the convex hull constructed around the detected feature points from consecutive frames. During the Aerial Vehicle (UAV) motion, the detection algorithm estimates the changes in the size of the area of the approaching obstacles. First, the method detects the feature points of the obstacles, then extracts the obstacles that have the probability of getting close toward the UAV. Secondly, by comparing the area ratio of the obstacle and the position of the UAV, the method decides if the detected obstacle may cause a collision. Finally, by estimating the obstacle 2D position in the image and combining with the tracked waypoints, the UAV performs the avoidance maneuver. The proposed algorithm was evaluated by performing real indoor and outdoor flights, and the obtained results show the accuracy of the proposed algorithm compared with other related works. PMID:28481277

  16. Building clinicians-researchers partnerships: lessons from diverse natural settings and practice-oriented initiatives.

    PubMed

    Castonguay, Louis G; Youn, Soo Jeong; Xiao, Henry; Muran, J Christopher; Barber, Jacques P

    2015-01-01

    In this concluding paper, we identify the type of studies conducted by 11 teams of contributors to a special issue on building clinicians-researchers partnerships. Those studies were conducted across a variety of clinical settings. We also integrate the lessons that have emerged from their collaborative initiatives in terms of obstacles faced, strategies adopted to address these challenges, benefits gained, and general recommendations offered to facilitate studies conducted with or by clinicians. The paper ends with the authors' thoughts about the future success of practice-oriented research in general.

  17. Mechanical energy assessment of adult with Down syndrome during walking with obstacle avoidance.

    PubMed

    Salami, Firooz; Vimercati, Sara Laura; Rigoldi, Chiara; Taebi, Amirtaha; Albertini, Giorgio; Galli, Manuela

    2014-08-01

    The aim of this study is analyzing the differences between plane walking and stepping over an obstacle for two groups of healthy people and people with Down syndrome and then, evaluating the movement efficiency between the groups by comprising of their mechanical energy exchanges. 39 adults including two groups of 21 people with Down syndrome (age: 21.6 ± 7 years) and 18 healthy people (age: 25.1 ± 2.4 years) participated in this research. The test has been done in two conditions, first in plane walking and second in walking with an obstacle (10% of the subject's height). The gait data were acquired using quantitative movement analysis, composed of an optoelectronic system (Elite2002, BTS) with eight infrared cameras. Mechanical energy exchanges are computed by dedicated software and finally the data including spatiotemporal parameters, mechanical energy parameters and energy recovery of gait cycle are analyzed by statistical software to find significant differences. Regards to spatiotemporal parameters velocity and step length are lower in people with Down syndrome. Mechanical energy parameters particularly energy recovery does not change from healthy people to people with Down syndrome. However, there are some differences in inter-group through plane walking to obstacle avoidance and it means people with Down syndrome probably use their residual abilities in the most efficient way to achieve the main goal of an efficient energy recovery. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. State-of-the-art technologies for intrusion and obstacle detection for railroad operations

    DOT National Transportation Integrated Search

    2007-07-01

    This report provides an update on the state-of-the-art technologies with intrusion and obstacle detection capabilities for rail rights of way (ROW) and crossings. A workshop entitled Intruder and Obstacle Detection Systems (IODS) for Railroads Requir...

  19. A Motion Planning Approach to Automatic Obstacle Avoidance during Concentric Tube Robot Teleoperation

    PubMed Central

    Torres, Luis G.; Kuntz, Alan; Gilbert, Hunter B.; Swaney, Philip J.; Hendrick, Richard J.; Webster, Robert J.; Alterovitz, Ron

    2015-01-01

    Concentric tube robots are thin, tentacle-like devices that can move along curved paths and can potentially enable new, less invasive surgical procedures. Safe and effective operation of this type of robot requires that the robot’s shaft avoid sensitive anatomical structures (e.g., critical vessels and organs) while the surgeon teleoperates the robot’s tip. However, the robot’s unintuitive kinematics makes it difficult for a human user to manually ensure obstacle avoidance along the entire tentacle-like shape of the robot’s shaft. We present a motion planning approach for concentric tube robot teleoperation that enables the robot to interactively maneuver its tip to points selected by a user while automatically avoiding obstacles along its shaft. We achieve automatic collision avoidance by precomputing a roadmap of collision-free robot configurations based on a description of the anatomical obstacles, which are attainable via volumetric medical imaging. We also mitigate the effects of kinematic modeling error in reaching the goal positions by adjusting motions based on robot tip position sensing. We evaluate our motion planner on a teleoperated concentric tube robot and demonstrate its obstacle avoidance and accuracy in environments with tubular obstacles. PMID:26413381

  20. A Motion Planning Approach to Automatic Obstacle Avoidance during Concentric Tube Robot Teleoperation.

    PubMed

    Torres, Luis G; Kuntz, Alan; Gilbert, Hunter B; Swaney, Philip J; Hendrick, Richard J; Webster, Robert J; Alterovitz, Ron

    2015-05-01

    Concentric tube robots are thin, tentacle-like devices that can move along curved paths and can potentially enable new, less invasive surgical procedures. Safe and effective operation of this type of robot requires that the robot's shaft avoid sensitive anatomical structures (e.g., critical vessels and organs) while the surgeon teleoperates the robot's tip. However, the robot's unintuitive kinematics makes it difficult for a human user to manually ensure obstacle avoidance along the entire tentacle-like shape of the robot's shaft. We present a motion planning approach for concentric tube robot teleoperation that enables the robot to interactively maneuver its tip to points selected by a user while automatically avoiding obstacles along its shaft. We achieve automatic collision avoidance by precomputing a roadmap of collision-free robot configurations based on a description of the anatomical obstacles, which are attainable via volumetric medical imaging. We also mitigate the effects of kinematic modeling error in reaching the goal positions by adjusting motions based on robot tip position sensing. We evaluate our motion planner on a teleoperated concentric tube robot and demonstrate its obstacle avoidance and accuracy in environments with tubular obstacles.

  1. Harnessing atomistic simulations to predict the rate at which dislocations overcome obstacles

    NASA Astrophysics Data System (ADS)

    Saroukhani, S.; Nguyen, L. D.; Leung, K. W. K.; Singh, C. V.; Warner, D. H.

    2016-05-01

    Predicting the rate at which dislocations overcome obstacles is key to understanding the microscopic features that govern the plastic flow of modern alloys. In this spirit, the current manuscript examines the rate at which an edge dislocation overcomes an obstacle in aluminum. Predictions were made using different popular variants of Harmonic Transition State Theory (HTST) and compared to those of direct Molecular Dynamics (MD) simulations. The HTST predictions were found to be grossly inaccurate due to the large entropy barrier associated with the dislocation-obstacle interaction. Considering the importance of finite temperature effects, the utility of the Finite Temperature String (FTS) method was then explored. While this approach was found capable of identifying a prominent reaction tube, it was not capable of computing the free energy profile along the tube. Lastly, the utility of the Transition Interface Sampling (TIS) approach was explored, which does not need a free energy profile and is known to be less reliant on the choice of reaction coordinate. The TIS approach was found capable of accurately predicting the rate, relative to direct MD simulations. This finding was utilized to examine the temperature and load dependence of the dislocation-obstacle interaction in a simple periodic cell configuration. An attractive rate prediction approach combining TST and simple continuum models is identified, and the strain rate sensitivity of individual dislocation obstacle interactions is predicted.

  2. Object-oriented analysis and design of an ECG storage and retrieval system integrated with an HIS.

    PubMed

    Wang, C; Ohe, K; Sakurai, T; Nagase, T; Kaihara, S

    1996-03-01

    For a hospital information system, object-oriented methodology plays an increasingly important role, especially for the management of digitized data, e.g., the electrocardiogram, electroencephalogram, electromyogram, spirogram, X-ray, CT and histopathological images, which are not yet computerized in most hospitals. As a first step in an object-oriented approach to hospital information management and storing medical data in an object-oriented database, we connected electrocardiographs to a hospital network and established the integration of ECG storage and retrieval systems with a hospital information system. In this paper, the object-oriented analysis and design of the ECG storage and retrieval systems is reported.

  3. Recovering an elastic obstacle containing embedded objects by the acoustic far-field measurements

    NASA Astrophysics Data System (ADS)

    Qu, Fenglong; Yang, Jiaqing; Zhang, Bo

    2018-01-01

    Consider the inverse scattering problem of time-harmonic acoustic waves by a 3D bounded elastic obstacle which may contain embedded impenetrable obstacles inside. We propose a novel and simple technique to show that the elastic obstacle can be uniquely recovered by the acoustic far-field pattern at a fixed frequency, disregarding its contents. Our method is based on constructing a well-posed modified interior transmission problem on a small domain and makes use of an a priori estimate for both the acoustic and elastic wave fields in the usual H 1-norm. In the case when there is no obstacle embedded inside the elastic body, our method gives a much simpler proof for the uniqueness result obtained previously in the literature (Natroshvili et al 2000 Rend. Mat. Serie VII 20 57-92 Monk and Selgas 2009 Inverse Problems Imaging 3 173-98).

  4. Asymmetries in visual search for conjunctive targets.

    PubMed

    Cohen, A

    1993-08-01

    Asymmetry is demonstrated between conjunctive targets in visual search with no detectable asymmetries between the individual features that compose these targets. Experiment 1 demonstrated this phenomenon for targets composed of color and shape. Experiment 2 and 4 demonstrate this asymmetry for targets composed of size and orientation and for targets composed of contrast level and orientation, respectively. Experiment 3 demonstrates that search rate of individual features cannot predict search rate for conjunctive targets. These results demonstrate the need for 2 levels of representations: one of features and one of conjunction of features. A model related to the modified feature integration theory is proposed to account for these results. The proposed model and other models of visual search are discussed.

  5. Using object-oriented analysis techniques to support system testing

    NASA Astrophysics Data System (ADS)

    Zucconi, Lin

    1990-03-01

    Testing of real-time control systems can be greatly facilitated by use of object-oriented and structured analysis modeling techniques. This report describes a project where behavior, process and information models built for a real-time control system were used to augment and aid traditional system testing. The modeling techniques used were an adaptation of the Ward/Mellor method for real-time systems analysis and design (Ward85) for object-oriented development. The models were used to simulate system behavior by means of hand execution of the behavior or state model and the associated process (data and control flow) and information (data) models. The information model, which uses an extended entity-relationship modeling technique, is used to identify application domain objects and their attributes (instance variables). The behavioral model uses state-transition diagrams to describe the state-dependent behavior of the object. The process model uses a transformation schema to describe the operations performed on or by the object. Together, these models provide a means of analyzing and specifying a system in terms of the static and dynamic properties of the objects which it manipulates. The various models were used to simultaneously capture knowledge about both the objects in the application domain and the system implementation. Models were constructed, verified against the software as-built and validated through informal reviews with the developer. These models were then hand-executed.

  6. Modern psychometrics for assessing achievement goal orientation: a Rasch analysis.

    PubMed

    Muis, Krista R; Winne, Philip H; Edwards, Ordene V

    2009-09-01

    A program of research is needed that assesses the psychometric properties of instruments designed to quantify students' achievement goal orientations to clarify inconsistencies across previous studies and to provide a stronger basis for future research. We conducted traditional psychometric and modern Rasch-model analyses of the Achievement Goals Questionnaire (AGQ, Elliot & McGregor, 2001) and the Patterns of Adaptive Learning Scale (PALS, Midgley et al., 2000) to provide an in-depth analysis of the two most popular instruments in educational psychology. For Study 1, 217 undergraduate students enrolled in educational psychology courses participated. Thirty-four were male and 181 were female (two did not respond). Participants completed the AGQ in the context of their educational psychology class. For Study 2, 126 undergraduate students enrolled in educational psychology courses participated. Thirty were male and 95 were female (one did not respond). Participants completed the PALS in the context of their educational psychology class. Traditional psychometric assessments of the AGQ and PALS replicated previous studies. For both, reliability estimates ranged from good to very good for raw subscale scores and fit for the models of goal orientations were good. Based on traditional psychometrics, the AGQ and PALS are valid and reliable indicators of achievement goals. Rasch analyses revealed that estimates of reliability for items were very good but respondent ability estimates varied from poor to good for both the AGQ and PALS. These findings indicate that items validly and reliably reflect a group's aggregate goal orientation, but using either instrument to characterize an individual's goal orientation is hazardous.

  7. Fresnel diffraction by spherical obstacles

    NASA Technical Reports Server (NTRS)

    Hovenac, Edward A.

    1989-01-01

    Lommel functions were used to solve the Fresnel-Kirchhoff diffraction integral for the case of a spherical obstacle. Comparisons were made between Fresnel diffraction theory and Mie scattering theory. Fresnel theory is then compared to experimental data. Experiment and theory typically deviated from one another by less than 10 percent. A unique experimental setup using mercury spheres suspended in a viscous fluid significantly reduced optical noise. The major source of error was due to the Gaussian-shaped laser beam.

  8. Attitudes and doping: a structural equation analysis of the relationship between athletes' attitudes, sport orientation and doping behaviour

    PubMed Central

    2007-01-01

    Background For effective deterrence methods, individual, systemic and situational factors that make an athlete or athlete group more susceptible to doping than others should be fully investigated. Traditional behavioural models assume that the behaviour in question is the ultimate end. However, growing evidence suggests that in doping situations, the doping behaviour is not the end but a means to an end, which is gaining competitive advantage. Therefore, models of doping should include and anti-doping policies should consider attitudes or orientations toward the specific target end, in addition to the attitude toward the 'tool' itself. Objectives The aim of this study was to empirically test doping related dispositions and attitudes of competitive athletes with the view of informing anti-doping policy developments and deterrence methods. To this end, the paper focused on the individual element of the drug availability – athlete's personality – situation triangle. Methods Data were collected by questionnaires containing a battery of psychological tests among competitive US male college athletes (n = 199). Outcome measures included sport orientation (win and goal orientation and competitiveness), doping attitude, beliefs and self-reported past or current use of doping. A structural equation model was developed based on the strength of relationships between these outcome measures. Results Whilst the doping model showed satisfactory fit, the results suggested that athletes' win and goal orientation and competitiveness do not play a statistically significant role in doping behaviour, but win orientation has an effect on doping attitude. The SEM analysis provided empirical evidence that sport orientation and doping behaviour is not directly related. Conclusion The considerable proportion of doping behaviour unexplained by the model suggests that other factors play an influential role in athletes' decisions regarding prohibited methods. Future research, followed by

  9. Orientation/Time Management Skill Training Lesson: Development and Evaluation

    DTIC Science & Technology

    1979-07-01

    instructional environment. This Orientation/ Time Management lesson provides students with appropriate role models for increasing acceptance of their...time savings can be obtained by a combination of this type of orientation and time management skill training with a computer-based progress targeting

  10. Overt attention toward oriented objects in free-viewing barn owls.

    PubMed

    Harmening, Wolf Maximilian; Orlowski, Julius; Ben-Shahar, Ohad; Wagner, Hermann

    2011-05-17

    Visual saliency based on orientation contrast is a perceptual product attributed to the functional organization of the mammalian brain. We examined this visual phenomenon in barn owls by mounting a wireless video microcamera on the owls' heads and confronting them with visual scenes that contained one differently oriented target among similarly oriented distracters. Without being confined by any particular task, the owls looked significantly longer, more often, and earlier at the target, thus exhibiting visual search strategies so far demonstrated in similar conditions only in primates. Given the considerable differences in phylogeny and the structure of visual pathways between owls and humans, these findings suggest that orientation saliency has computational optimality in a wide variety of ecological contexts, and thus constitutes a universal building block for efficient visual information processing in general.

  11. A Cross-Case Analysis of Three Social Justice-Oriented Education Programs

    ERIC Educational Resources Information Center

    Rodriguez, Mariela A.; Chambers, Terah Venzant; Gonzalez, Maria Luisa; Scheurich, James Joseph

    2010-01-01

    This cross-case analysis was based on three main questions that addressed three social justice-oriented education programs. The three questions were: 1) What critical elements underlie programs that prepare professionals for social justice? 2) What can we learn from these programs in support of educational-leadership programs whose aim is to…

  12. Wind turbines: current status, obstacles, trends and technologies

    NASA Astrophysics Data System (ADS)

    Konstantinidis, E. I.; Botsaris, P. N.

    2016-11-01

    The last decade the installation of wind farms around the world is spreading rapidly and wind energy has become a significant factor for promoting sustainable development. The scope of the present study is to indicate the present status of global wind power expansion as well as the current state of the art in the field of wind turbine technology. The RAM (reliability/availability/maintenance) section is also examined and the Levelized Cost of Energy for onshore/ offshore electricity production is presented. Negative consequences that go with the rapid expansion of wind power like accidents, environmental effects, etc. are highlighted. Especially visual impact to the landscape and noise pollution are some factors that provoke social reactions. Moreover, the complicated and long permitted process of a wind power plant, the high capital cost of the investment and the grid instability due to the intermittent nature of wind, are also significant obstacles in the development of the wind energy production. The current trends in the field of research and development of onshore and offshore wind power production are analyzed. Finally the present study is trying to achieve an estimation of where the wind industry targets for the years to come.

  13. Human cortical activity evoked by contextual processing in attentional orienting.

    PubMed

    Zhao, Shuo; Li, Chunlin; Uono, Shota; Yoshimura, Sayaka; Toichi, Motomi

    2017-06-07

    The ability to assess another person's direction of attention is paramount in social communication, many studies have reported a similar pattern between gaze and arrow cues in attention orienting. Neuroimaging research has also demonstrated no qualitative differences in attention to gaze and arrow cues. However, these studies were implemented under simple experiment conditions. Researchers have highlighted the importance of contextual processing (i.e., the semantic congruence between cue and target) in attentional orienting, showing that attentional orienting by social gaze or arrow cues could be modulated through contextual processing. Here, we examine the neural activity of attentional orienting by gaze and arrow cues in response to contextual processing using functional magnetic resonance imaging. The results demonstrated that the influence of neural activity through contextual processing to attentional orienting occurred under invalid conditions (when the cue and target were incongruent versus congruent) in the ventral frontoparietal network, although we did not identify any differences in the neural substrates of attentional orienting in contextual processing between gaze and arrow cues. These results support behavioural data of attentional orienting modulated by contextual processing based on the neurocognitive architecture.

  14. The Volatility of Data Space: Topology Oriented Sensitivity Analysis

    PubMed Central

    Du, Jing; Ligmann-Zielinska, Arika

    2015-01-01

    Despite the difference among specific methods, existing Sensitivity Analysis (SA) technologies are all value-based, that is, the uncertainties in the model input and output are quantified as changes of values. This paradigm provides only limited insight into the nature of models and the modeled systems. In addition to the value of data, a potentially richer information about the model lies in the topological difference between pre-model data space and post-model data space. This paper introduces an innovative SA method called Topology Oriented Sensitivity Analysis, which defines sensitivity as the volatility of data space. It extends SA into a deeper level that lies in the topology of data. PMID:26368929

  15. Achievements and obstacles of remyelinating therapies in multiple sclerosis.

    PubMed

    Stangel, Martin; Kuhlmann, Tanja; Matthews, Paul M; Kilpatrick, Trevor J

    2017-12-01

    Remyelination in the CNS is the natural process of damage repair in demyelinating diseases such as multiple sclerosis (MS). However, remyelination becomes inadequate in many people with MS, which results in axonal degeneration and clinical disability. Enhancement of remyelination is a logical therapeutic goal; nevertheless, all currently licensed therapies for MS are immunomodulatory and do not support remyelination directly. Several molecular pathways have been identified as potential therapeutic targets to induce remyelination, and some of these have now been assessed in proof-of-concept clinical trials. However, trial design faces several obstacles: optimal clinical or paraclinical outcome measures to assess remyelination remain ill-defined, and identification of the ideal timing of therapy is also a crucial issue. In addition, realistic expectations are needed concerning the probable benefits of such therapies. Nevertheless, approaches that enhance remyelination are likely to be protective for axons and so could prevent long-term neurodegeneration. Future MS treatment paradigms, therefore, are likely to comprise a combinatorial approach that involves both immunomodulatory and regenerative treatments.

  16. Transporters at CNS Barrier Sites: Obstacles or Opportunities for Drug Delivery?

    PubMed Central

    Sanchez-Covarrubias, Lucy; Slosky, Lauren M.; Thompson, Brandon J.; Davis, Thomas P.; Ronaldson, Patrick T.

    2014-01-01

    The blood-brain barrier (BBB) and blood-cerebrospinal fluid (BCSF) barriers are critical determinants of CNS homeostasis. Additionally, the BBB and BCSF barriers are formidable obstacles to effective CNS drug delivery. These brain barrier sites express putative influx and efflux transporters that precisely control permeation of circulating solutes including drugs. The study of transporters has enabled a shift away from “brute force” approaches to delivering drugs by physically circumventing brain barriers towards chemical approaches that can target specific compounds of the BBB and/or BCSF barrier. However, our understanding of transporters at the BBB and BCSF barriers has primarily focused on understanding efflux transporters that efficiently prevent drugs from attaining therapeutic concentrations in the CNS. Recently, through the characterization of multiple endogenously expressed uptake transporters, this paradigm has shifted to the study of brain transporter targets that can facilitate drug delivery (i.e., influx transporters). Additionally, signaling pathways and trafficking mechanisms have been identified for several endogenous BBB/BCSF transporters, thereby offering even more opportunities to understand how transporters can be exploited for optimization of CNS drug delivery. This review presents an overview of the BBB and BCSF barrier as well as the many families of transporters functionally expressed at these barrier sites. Furthermore, we present an overview of various strategies that have been designed and utilized to deliver therapeutic agents to the brain with a particular emphasis on those approaches that directly target endogenous BBB/BCSF barrier transporters. PMID:23789948

  17. Performance Impact of Deflagration to Detonation Transition Enhancing Obstacles

    NASA Technical Reports Server (NTRS)

    Paxson, Daniel E.; Schauer, Frederick; Hopper, David

    2012-01-01

    A sub-model is developed to account for the drag and heat transfer enhancement resulting from deflagration-to-detonation (DDT) inducing obstacles commonly used in pulse detonation engines (PDE). The sub-model is incorporated as a source term in a time-accurate, quasi-onedimensional, CFD-based PDE simulation. The simulation and sub-model are then validated through comparison with a particular experiment in which limited DDT obstacle parameters were varied. The simulation is then used to examine the relative contributions from drag and heat transfer to the reduced thrust which is observed. It is found that heat transfer is far more significant than aerodynamic drag in this particular experiment.

  18. Micro air vehicle autonomous obstacle avoidance from stereo-vision

    NASA Astrophysics Data System (ADS)

    Brockers, Roland; Kuwata, Yoshiaki; Weiss, Stephan; Matthies, Lawrence

    2014-06-01

    We introduce a new approach for on-board autonomous obstacle avoidance for micro air vehicles flying outdoors in close proximity to structure. Our approach uses inverse-range, polar-perspective stereo-disparity maps for obstacle detection and representation, and deploys a closed-loop RRT planner that considers flight dynamics for trajectory generation. While motion planning is executed in 3D space, we reduce collision checking to a fast z-buffer-like operation in disparity space, which allows for significant speed-up compared to full 3d methods. Evaluations in simulation illustrate the robustness of our approach, whereas real world flights under tree canopy demonstrate the potential of the approach.

  19. Omniview motionless camera orientation system

    NASA Technical Reports Server (NTRS)

    Zimmermann, Steven D. (Inventor); Martin, H. Lee (Inventor)

    1999-01-01

    A device for omnidirectional image viewing providing pan-and-tilt orientation, rotation, and magnification within a hemispherical field-of-view that utilizes no moving parts. The imaging device is based on the effect that the image from a fisheye lens, which produces a circular image of at entire hemispherical field-of-view, which can be mathematically corrected using high speed electronic circuitry. More specifically, an incoming fisheye image from any image acquisition source is captured in memory of the device, a transformation is performed for the viewing region of interest and viewing direction, and a corrected image is output as a video image signal for viewing, recording, or analysis. As a result, this device can accomplish the functions of pan, tilt, rotation, and zoom throughout a hemispherical field-of-view without the need for any mechanical mechanisms. The preferred embodiment of the image transformation device can provide corrected images at real-time rates, compatible with standard video equipment. The device can be used for any application where a conventional pan-and-tilt or orientation mechanism might be considered including inspection, monitoring, surveillance, and target acquisition.

  20. Obstacles and challenges following the partial decriminalisation of abortion in Colombia.

    PubMed

    Amado, Eduardo Díaz; Calderón García, Maria Cristina; Cristancho, Katherine Romero; Salas, Elena Prada; Hauzeur, Eliane Barreto

    2010-11-01

    During a highly contested process, abortion was partially decriminalised in Colombia in 2006 by the Constitutional Court: when the pregnancy threatens a woman's life or health, in cases of severe fetal malformations incompatible with life, and in cases of rape, incest or unwanted insemination. However, Colombian women still face obstacles to accessing abortion services. This is illustrated by 36 cases of women who in 2006-08 were denied the right to a lawful termination of pregnancy, or had unjustified obstacles put in their path which delayed the termination, which are analysed in this article. We argue that the obstacles resulted from fundamental disagreements about abortion and misunderstandings regarding the ethical, legal and medical requirements arising from the Court's decision. In order to avoid obstacles such as demands for a judge's authorisation, institutional claims of conscientious objection, rejection of a claim of rape, or refusal of health insurance coverage for a legal termination, which constitute discrimination against women, three main strategies are suggested: public ownership of the Court's decision by all Colombian citizens, a professional approach by those involved in the provision of services in line with the law, and monitoring of its implementation by governmental and non-governmental organisations. Copyright © 2010 Reproductive Health Matters. Published by Elsevier Ltd. All rights reserved.

  1. Visualization of the membrane engineering concept: evidence for the specific orientation of electroinserted antibodies and selective binding of target analytes.

    PubMed

    Kokla, Anna; Blouchos, Petros; Livaniou, Evangelia; Zikos, Christos; Kakabakos, Sotiris E; Petrou, Panagiota S; Kintzios, Spyridon

    2013-12-01

    Membrane engineering is a generic methodology for increasing the selectivity of a cell biosensor against a target molecule, by electroinserting target-specific receptor-like molecules on the cell surface. Previous studies have elucidated the biochemical aspects of the interaction between various analytes (including viruses) and their homologous membrane-engineered cells. In the present study, purified anti-biotin antibodies from a rabbit antiserum along with in-house prepared biotinylated bovine serum albumin (BSA) were used as a model antibody-antigen pair of molecules for facilitating membrane engineering experiments. It was proven, with the aid of fluorescence microscopy, that (i) membrane-engineered cells incorporated the specific antibodies in the correct orientation and that (ii) the inserted antibodies are selectively interacting with the homologous target molecules. This is the first time the actual working concept of membrane engineering has been visualized, thus providing a final proof of the concept behind this innovative process. In addition, the fluorescence microscopy measurements were highly correlated with bioelectric measurements done with the aid of a bioelectric recognition assay. Copyright © 2013 John Wiley & Sons, Ltd.

  2. Impaired anticipatory control of grasp during obstacle crossing in Parkinson's disease.

    PubMed

    McIsaac, Tara L; Diermayr, Gudrun; Albert, Frederic

    2012-05-16

    During self-paced walking, people with Parkinson's disease maintain anticipatory control during object grasping. However, common functional tasks often include carrying an object while changing step patterns mid-path and maneuvering over obstacles, increasing task complexity and attentional demands. Thus, the present study investigated the effect of Parkinson's disease on the modulation of grasping force changes as a function of gait-related inertial forces. Subjects with Parkinson's disease maintained the ability to scale and to couple over time their grip and inertial forces while walking at irregular step lengths, but were unable to maintain the temporal coupling of grasping forces compared to controls during obstacle crossing. We suggest that this deterioration in anticipatory control is associated with the increased demands of task complexity and attention during obstacle crossing. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  3. Embodied memory allows accurate and stable perception of hidden objects despite orientation change.

    PubMed

    Pan, Jing Samantha; Bingham, Ned; Bingham, Geoffrey P

    2017-07-01

    Rotating a scene in a frontoparallel plane (rolling) yields a change in orientation of constituent images. When using only information provided by static images to perceive a scene after orientation change, identification performance typically decreases (Rock & Heimer, 1957). However, rolling generates optic flow information that relates the discrete, static images (before and after the change) and forms an embodied memory that aids recognition. The embodied memory hypothesis predicts that upon detecting a continuous spatial transformation of image structure, or in other words, seeing the continuous rolling process and objects undergoing rolling observers should accurately perceive objects during and after motion. Thus, in this case, orientation change should not affect performance. We tested this hypothesis in three experiments and found that (a) using combined optic flow and image structure, participants identified locations of previously perceived but currently occluded targets with great accuracy and stability (Experiment 1); (b) using combined optic flow and image structure information, participants identified hidden targets equally well with or without 30° orientation changes (Experiment 2); and (c) when the rolling was unseen, identification of hidden targets after orientation change became worse (Experiment 3). Furthermore, when rolling was unseen, although target identification was better when participants were told about the orientation change than when they were not told, performance was still worse than when there was no orientation change. Therefore, combined optic flow and image structure information, not mere knowledge about the rolling, enables accurate and stable perception despite orientation change. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  4. Characterizing Laminar Flame Interactions with Turbulent Fluidic Jets and Solid Obstacles for Turbulence Induction

    NASA Astrophysics Data System (ADS)

    Gerdts, Stephen; Chambers, Jessica; Ahmed, Kareem

    2016-11-01

    A detonation engine's fundamental design concept focuses on enhancing the Deflagration to Detonation Transition (DDT), the process through which subsonic flames accelerate to form a spontaneous detonation wave. Flame acceleration is driven by turbulent interactions that expand the reaction zone and induce mixing of products and reactants. Turbulence in a duct can be generated using solid obstructions, fluidic obstacles, duct angle changes, and wall skin friction. Solid obstacles have been previously explored and offer repeatable turbulence induction at the cost of pressure losses and additional system weight. Fluidic jet obstacles are a novel technique that provide advantages such as the ability to be throttled, allowing for active control of combustion modes. The scope of the present work is to expand the experimental database of varying parameters such as main flow and jet equivalence ratios, fluidic momentum ratios, and solid obstacle blockage ratios. Schlieren flow visualization and particle image velocimetry (PIV) are employed to investigate turbulent flame dynamics throughout the interaction. Optimum conditions that lead to flame acceleration for both solid and fluidic obstacles will be determined. American Chemical Society.

  5. Obstacle Classification and 3D Measurement in Unstructured Environments Based on ToF Cameras

    PubMed Central

    Yu, Hongshan; Zhu, Jiang; Wang, Yaonan; Jia, Wenyan; Sun, Mingui; Tang, Yandong

    2014-01-01

    Inspired by the human 3D visual perception system, we present an obstacle detection and classification method based on the use of Time-of-Flight (ToF) cameras for robotic navigation in unstructured environments. The ToF camera provides 3D sensing by capturing an image along with per-pixel 3D space information. Based on this valuable feature and human knowledge of navigation, the proposed method first removes irrelevant regions which do not affect robot's movement from the scene. In the second step, regions of interest are detected and clustered as possible obstacles using both 3D information and intensity image obtained by the ToF camera. Consequently, a multiple relevance vector machine (RVM) classifier is designed to classify obstacles into four possible classes based on the terrain traversability and geometrical features of the obstacles. Finally, experimental results in various unstructured environments are presented to verify the robustness and performance of the proposed approach. We have found that, compared with the existing obstacle recognition methods, the new approach is more accurate and efficient. PMID:24945679

  6. Sexual orientation and adolescent substance use: a meta-analysis and methodological review*

    PubMed Central

    Marshal, Michael P.; Friedman, Mark S.; Stall, Ron; King, Kevin M.; Miles, Jonathan; Gold, Melanie A.; Bukstein, Oscar G.; Morse, Jennifer Q.

    2009-01-01

    Aims Several decades of research have shown that lesbian, gay and bisexual (LGB) adults are at high risk for substance use and substance use disorders (SUDs). These problems may often start prior to young adulthood; however, relatively little is known about risk for substance use in LGB adolescents. The primary aims of this paper were to conduct a meta-analysis of the relationship between sexual orientation and adolescent substance use and a systematic review and critique of the methodological characteristics of this literature. Methods Medical and social science journals were searched using Medline and PsychInfo. Studies were included if they tested the relationship between sexual orientation and adolescent substance use. Eighteen published studies were identified. Data analysis procedures followed expert guidelines, and used National Institutes of Health (NIH)-sponsored meta-analysis software. Results LGB adolescents reported higher rates of substance use compared to heterosexual youth (overall odds ratio = 2.89, Cohen's d = 0.59). Effect sizes varied by gender, bisexuality status, sexual orientation definition and recruitment source. None of the studies tested mediation and only one tested moderation. One employed a matched comparison group design, one used a longitudinal design, and very few controlled for possible confounding variables. Conclusions The odds of substance use for LGB youth were, on average, 190% higher than for heterosexual youth and substantially higher within some subpopulations of LGB youth (340% higher for bisexual youth, 400% higher for females). Causal mechanisms, protective factors and alternative explanations for this effect, as well as long-term substance use outcomes in LGB youth, remain largely unknown. PMID:18339100

  7. Echolocation behaviour of the big brown bat (Eptesicus fuscus) in an obstacle avoidance task of increasing difficulty.

    PubMed

    Sändig, Sonja; Schnitzler, Hans-Ulrich; Denzinger, Annette

    2014-08-15

    Four big brown bats (Eptesicus fuscus) were challenged in an obstacle avoidance experiment to localize vertically stretched wires requiring progressively greater accuracy by diminishing the wire-to-wire distance from 50 to 10 cm. The performance of the bats decreased with decreasing gap size. The avoidance task became very difficult below a wire separation of 30 cm, which corresponds to the average wingspan of E. fuscus. Two of the bats were able to pass without collisions down to a gap size of 10 cm in some of the flights. The other two bats only managed to master gap sizes down to 20 and 30 cm, respectively. They also performed distinctly worse at all other gap sizes. With increasing difficulty of the task, the bats changed their flight and echolocation behaviour. Especially at gap sizes of 30 cm and below, flight paths increased in height and flight speed was reduced. In addition, the bats emitted approach signals that were arranged in groups. At all gap sizes, the largest numbers of pulses per group were observed in the last group before passing the obstacle. The more difficult the obstacle avoidance task, the more pulses there were in the groups and the shorter the within-group pulse intervals. In comparable situations, the better-performing bats always emitted groups with more pulses than the less well-performing individuals. We hypothesize that the accuracy of target localization increases with the number of pulses per group and that each group is processed as a package. © 2014. Published by The Company of Biologists Ltd.

  8. Perceived Sexual Orientation of Men and Women with Eating Disorders and Obesity.

    PubMed

    Essayli, Jamal H; Murakami, Jessica M; Latner, Janet D

    2018-06-04

    The present study explores the perceived sexual orientation of hypothetical men and women with various eating disorders and obesity. Undergraduates were randomly provided with one vignette describing a male or female with anorexia nervosa (AN), bulimia nervosa (BN), binge-eating disorder, or obesity and were asked about the target's likely sexual orientation. Significant differences emerged between male and female targets with AN and BN on the forced-choice question, with a greater percentage of participants indicating that the male targets were probably non-heterosexual. On continuous items, participants rated the female targets as significantly more likely to be heterosexual and significantly less likely to be homosexual than male targets. The general public may be more likely to perceive men with eating disorders as gay or bisexual relative to females with eating disorders. Perceived sexual orientation might be an important factor to consider when exploring the potentially unique perspectives of men with eating disorders.

  9. Blindness enhances auditory obstacle circumvention: Assessing echolocation, sensory substitution, and visual-based navigation

    PubMed Central

    Scarfe, Amy C.; Moore, Brian C. J.; Pardhan, Shahina

    2017-01-01

    Performance for an obstacle circumvention task was assessed under conditions of visual, auditory only (using echolocation) and tactile (using a sensory substitution device, SSD) guidance. A Vicon motion capture system was used to measure human movement kinematics objectively. Ten normally sighted participants, 8 blind non-echolocators, and 1 blind expert echolocator navigated around a 0.6 x 2 m obstacle that was varied in position across trials, at the midline of the participant or 25 cm to the right or left. Although visual guidance was the most effective, participants successfully circumvented the obstacle in the majority of trials under auditory or SSD guidance. Using audition, blind non-echolocators navigated more effectively than blindfolded sighted individuals with fewer collisions, lower movement times, fewer velocity corrections and greater obstacle detection ranges. The blind expert echolocator displayed performance similar to or better than that for the other groups using audition, but was comparable to that for the other groups using the SSD. The generally better performance of blind than of sighted participants is consistent with the perceptual enhancement hypothesis that individuals with severe visual deficits develop improved auditory abilities to compensate for visual loss, here shown by faster, more fluid, and more accurate navigation around obstacles using sound. PMID:28407000

  10. Blindness enhances auditory obstacle circumvention: Assessing echolocation, sensory substitution, and visual-based navigation.

    PubMed

    Kolarik, Andrew J; Scarfe, Amy C; Moore, Brian C J; Pardhan, Shahina

    2017-01-01

    Performance for an obstacle circumvention task was assessed under conditions of visual, auditory only (using echolocation) and tactile (using a sensory substitution device, SSD) guidance. A Vicon motion capture system was used to measure human movement kinematics objectively. Ten normally sighted participants, 8 blind non-echolocators, and 1 blind expert echolocator navigated around a 0.6 x 2 m obstacle that was varied in position across trials, at the midline of the participant or 25 cm to the right or left. Although visual guidance was the most effective, participants successfully circumvented the obstacle in the majority of trials under auditory or SSD guidance. Using audition, blind non-echolocators navigated more effectively than blindfolded sighted individuals with fewer collisions, lower movement times, fewer velocity corrections and greater obstacle detection ranges. The blind expert echolocator displayed performance similar to or better than that for the other groups using audition, but was comparable to that for the other groups using the SSD. The generally better performance of blind than of sighted participants is consistent with the perceptual enhancement hypothesis that individuals with severe visual deficits develop improved auditory abilities to compensate for visual loss, here shown by faster, more fluid, and more accurate navigation around obstacles using sound.

  11. On the rules of integration of crowded orientation signals

    PubMed Central

    Põder, Endel

    2012-01-01

    Crowding is related to an integration of feature signals over an inappropriately large area in the visual periphery. The rules of this integration are still not well understood. This study attempts to understand how the orientation signals from the target and flankers are combined. A target Gabor, together with 2, 4, or 6 flanking Gabors, was briefly presented in a peripheral location (4° eccentricity). The observer's task was to identify the orientation of the target (eight-alternative forced-choice). Performance was found to be nonmonotonically dependent on the target–flanker orientation difference (a drop at intermediate differences). For small target–flanker differences, a strong assimilation bias was observed. An effect of the number of flankers was found for heterogeneous flankers only. It appears that different rules of integration are used, dependent on some salient aspects (target pop-out, homogeneity–heterogeneity) of the stimulus pattern. The strategy of combining simple rules may be explained by the goal of the visual system to encode potentially important aspects of a stimulus with limited processing resources and using statistical regularities of the natural visual environment. PMID:23145295

  12. Quantitative characterization of galectin-3-C affinity mass spectrometry measurements: Comprehensive data analysis, obstacles, shortcuts and robustness.

    PubMed

    Haramija, Marko; Peter-Katalinić, Jasna

    2017-10-30

    Affinity mass spectrometry (AMS) is an emerging tool in the field of the study of protein•carbohydrate complexes. However, experimental obstacles and data analysis are preventing faster integration of AMS methods into the glycoscience field. Here we show how analysis of direct electrospray ionization mass spectrometry (ESI-MS) AMS data can be simplified for screening purposes, even for complex AMS spectra. A direct ESI-MS assay was tested in this study and binding data for the galectin-3C•lactose complex were analyzed using a comprehensive and simplified data analysis approach. In the comprehensive data analysis approach, noise, all protein charge states, alkali ion adducts and signal overlap were taken into account. In a simplified approach, only the intensities of the fully protonated free protein and the protein•carbohydrate complex for the main protein charge state were taken into account. In our study, for high intensity signals, noise was negligible, sodiated protein and sodiated complex signals cancelled each other out when calculating the K d value, and signal overlap influenced the Kd value only to a minor extent. Influence of these parameters on low intensity signals was much higher. However, low intensity protein charge states should be avoided in quantitative AMS analyses due to poor ion statistics. The results indicate that noise, alkali ion adducts, signal overlap, as well as low intensity protein charge states, can be neglected for preliminary experiments, as well as in screening assays. One comprehensive data analysis performed as a control should be sufficient to validate this hypothesis for other binding systems as well. Copyright © 2017 John Wiley & Sons, Ltd.

  13. Integrating end-to-end threads of control into object-oriented analysis and design

    NASA Technical Reports Server (NTRS)

    Mccandlish, Janet E.; Macdonald, James R.; Graves, Sara J.

    1993-01-01

    Current object-oriented analysis and design methodologies fall short in their use of mechanisms for identifying threads of control for the system being developed. The scenarios which typically describe a system are more global than looking at the individual objects and representing their behavior. Unlike conventional methodologies that use data flow and process-dependency diagrams, object-oriented methodologies do not provide a model for representing these global threads end-to-end. Tracing through threads of control is key to ensuring that a system is complete and timing constraints are addressed. The existence of multiple threads of control in a system necessitates a partitioning of the system into processes. This paper describes the application and representation of end-to-end threads of control to the object-oriented analysis and design process using object-oriented constructs. The issue of representation is viewed as a grouping problem, that is, how to group classes/objects at a higher level of abstraction so that the system may be viewed as a whole with both classes/objects and their associated dynamic behavior. Existing object-oriented development methodology techniques are extended by adding design-level constructs termed logical composite classes and process composite classes. Logical composite classes are design-level classes which group classes/objects both logically and by thread of control information. Process composite classes further refine the logical composite class groupings by using process partitioning criteria to produce optimum concurrent execution results. The goal of these design-level constructs is to ultimately provide the basis for a mechanism that can support the creation of process composite classes in an automated way. Using an automated mechanism makes it easier to partition a system into concurrently executing elements that can be run in parallel on multiple processors.

  14. Determinants, obstacles, sources and cooperation to innovation in Portuguese firms, using community innovation survey

    NASA Astrophysics Data System (ADS)

    Correia, Aldina; Braga, Alexandra; Braga, Vitor

    2017-06-01

    Innovation is a topic of interest for the management researchers, confirmed by the creation of a Community Innovation Survey, which is an harmonised tool designed to provide information about Innovation in European Union enterprises. In this study, we use factorial analysis to identify the determinants and obstacles to innovation in Portuguese firms. The sources of innovation and cooperation to innovation are also analysed, using crossed information. For the determinants of innovation six factors were identified: Production costs and impacts to health and environment, Process and product innovation, Organizational innovation, Institutional sources of information, Others sources of information and Market sources of information. Obstacles to innovation were clustered into three groups: Knowledge and market factors, Cost factors and Reasons not to innovate. The main sources of innovation identified, in this study, are Suppliers and Clients, located in Portugal and in Europe. Cooperation partners are also majority Clients and Suppliers, in addition to other enterprises in the same group.

  15. 77 FR 50014 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-20

    ... navigational facilities, adding new obstacles, or changing air traffic requirements. These changes are designed.... Intl. 20-Sep-12 TX Houston Sugar Land Rgnl.... 2/8058 7/19/12 TAKEOFF MINIMUMS AND (OBSTACLE) DP, Amdt...

  16. Identifying Obstacles to Adoption in New York State's Out-of-Home Care System.

    ERIC Educational Resources Information Center

    Avery, Rosemary J.

    1999-01-01

    This study queried caseworkers for 77 New York children in out-of-home care still waiting for placement to determine obstacles to permanent adoption. Questionnaires sought demographics, placement efforts, and caseworker opinions. Findings indicated several obstacles, including the following: child's strong emotional ties to family (foster or…

  17. Critical Care Nurses' Perceptions of End-of-Life Care Obstacles: Comparative 17-Year Data.

    PubMed

    Beckstrand, Renea L; Lamoreaux, Nicole; Luthy, Karlen E; Macintosh, Janelle L B

    Nurses working in intensive care units (ICUs) frequently care for patients and their families at the end of life (EOL). Providing high-quality EOL care is important for both patients and families, yet ICU nurses face many obstacles that hinder EOL care. Researchers have identified various ICU nurse-perceived obstacles, but no studies have been found addressing the progress that has been made for the last 17 years. The aims of this study were to determine the most common and current obstacles in EOL care as perceived by ICU nurses and then to evaluate whether meaningful changes have occurred since data were first gathered in 1998. A quantitative-qualitative mixed methods design was used. A random, geographically dispersed sample of 2000 members of the American Association of Critical-Care Nurses was surveyed. Five obstacle items increased in mean score and rank as compared with 1999 data including (1) family not understanding what the phrase "lifesaving measures" really means, (2) providing lifesaving measures at families' requests despite patient's advance directive listing no such care, (3) family not accepting patient's poor prognosis, (4) family members fighting about the use of life support, and (5) not enough time to provide EOL care because the nurse is consumed with lifesaving measures attempting to save the patient's life. Five obstacle items decreased in mean score and rank compared with 1999 data including (1) physicians differing in opinion about care of the patient, (2) family and friends who continually call the nurse rather than calling the designated family member, (3) physicians who are evasive and avoid families, (4) nurses having to deal with angry families, and (5) nurses not knowing their patient's wishes regarding continuing with tests and treatments. Obstacles in EOL care, as perceived by critical care nurses, still exist. Family-related obstacles have increased over time. Obstacles related to families may not be easily overcome as each family

  18. Prevention 0f Unwanted Free-Declaration of Static Obstacles in Probability Occupancy Grids

    NASA Astrophysics Data System (ADS)

    Krause, Stefan; Scholz, M.; Hohmann, R.

    2017-10-01

    Obstacle detection and avoidance are major research fields in unmanned aviation. Map based obstacle detection approaches often use discrete world representations such as probabilistic grid maps to fuse incremental environment data from different views or sensors to build a comprehensive representation. The integration of continuous measurements into a discrete representation can result in rounding errors which, in turn, leads to differences between the artificial model and real environment. The cause of these deviations is a low spatial resolution of the world representation comparison to the used sensor data. Differences between artificial representations which are used for path planning or obstacle avoidance and the real world can lead to unexpected behavior up to collisions with unmapped obstacles. This paper presents three approaches to the treatment of errors that can occur during the integration of continuous laser measurement in the discrete probabilistic grid. Further, the quality of the error prevention and the processing performance are compared with real sensor data.

  19. Determinants of Benin elementary school science teachers' orientation toward inquiry-based instructional practices

    NASA Astrophysics Data System (ADS)

    Gado, Issaou

    The Republic of Benin (West Africa) undertook a nationwide curriculum reform that put an emphasis on inquiry-based instructional practices. Little, if any, research has been conducted to explore factors that could be related to teachers' orientation toward inquiry instructional practices. The purpose of this research study was to investigate factors and concerns that determine Benin elementary school teachers' orientation toward the use of inquiry-based instruction in the teaching of science. The study followed a naturalistic inquiry methodology combining a correlational ex post facto design and an observational case-study design. The theory of Planned Behavior was the conceptual framework used to design the study. Two hundred (N = 200) elementary school teachers and three (n = 3) case study participants were purposively selected. Data was gathered via the Revised Science Attitude Scale (Thompson & Shrigley, 1986), the Science Teachers' Ideological Preference Scale (Jones & Harty, 1978), open-ended questions, interviews, and classroom observations using audiorecorders, videorecorders, and the researcher-contextualized version of the Observational System for the Analysis of Classroom Instruction (Hough, 1966). Qualitative and quantitative data provided a deeper understanding of participants' responses. Quantitative measures indicated that Benin elementary school teachers have positive attitudes toward school science, significant positive orientation toward both inquiry-based instruction and traditional non inquiry-based instruction, and higher orientation toward inquiry-based instruction than traditional non inquiry-based instruction. Attitude toward handling materials for investigations was found to significantly contribute to the prediction of participants' inquiry orientation. Qualitative analyses of participants' responses indicated that the expectations of educational leaders, individual motivation to comply with the program, a perceived control of the

  20. 78 FR 54564 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-05

    ... Linder Rgnl, Takeoff Minimums and Obstacle DP, Amdt 1 Venice, FL, Venice Muni, RNAV (GPS) RWY 5, Orig Venice, FL, Venice Muni, RNAV (GPS) RWY 23, Orig Venice, FL, Venice Muni, Takeoff Minimums and Obstacle...

  1. Pigeon interaction mode switch-based UAV distributed flocking control under obstacle environments.

    PubMed

    Qiu, Huaxin; Duan, Haibin

    2017-11-01

    Unmanned aerial vehicle (UAV) flocking control is a serious and challenging problem due to local interactions and changing environments. In this paper, a pigeon flocking model and a pigeon coordinated obstacle-avoiding model are proposed based on a behavior that pigeon flocks will switch between hierarchical and egalitarian interaction mode at different flight phases. Owning to the similarity between bird flocks and UAV swarms in essence, a distributed flocking control algorithm based on the proposed pigeon flocking and coordinated obstacle-avoiding models is designed to coordinate a heterogeneous UAV swarm to fly though obstacle environments with few informed individuals. The comparative simulation results are elaborated to show the feasibility, validity and superiority of our proposed algorithm. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  2. Open source tracking and analysis of adult Drosophila locomotion in Buridan's paradigm with and without visual targets.

    PubMed

    Colomb, Julien; Reiter, Lutz; Blaszkiewicz, Jedrzej; Wessnitzer, Jan; Brembs, Bjoern

    2012-01-01

    Insects have been among the most widely used model systems for studying the control of locomotion by nervous systems. In Drosophila, we implemented a simple test for locomotion: in Buridan's paradigm, flies walk back and forth between two inaccessible visual targets [1]. Until today, the lack of easily accessible tools for tracking the fly position and analyzing its trajectory has probably contributed to the slow acceptance of Buridan's paradigm. We present here a package of open source software designed to track a single animal walking in a homogenous environment (Buritrack) and to analyze its trajectory. The Centroid Trajectory Analysis (CeTrAn) software is coded in the open source statistics project R. It extracts eleven metrics and includes correlation analyses and a Principal Components Analysis (PCA). It was designed to be easily customized to personal requirements. In combination with inexpensive hardware, these tools can readily be used for teaching and research purposes. We demonstrate the capabilities of our package by measuring the locomotor behavior of adult Drosophila melanogaster (whose wings were clipped), either in the presence or in the absence of visual targets, and comparing the latter to different computer-generated data. The analysis of the trajectories confirms that flies are centrophobic and shows that inaccessible visual targets can alter the orientation of the flies without changing their overall patterns of activity. Using computer generated data, the analysis software was tested, and chance values for some metrics (as well as chance value for their correlation) were set. Our results prompt the hypothesis that fixation behavior is observed only if negative phototaxis can overcome the propensity of the flies to avoid the center of the platform. Together with our companion paper, we provide new tools to promote Open Science as well as the collection and analysis of digital behavioral data.

  3. Computer-aided target tracking in motion analysis studies

    NASA Astrophysics Data System (ADS)

    Burdick, Dominic C.; Marcuse, M. L.; Mislan, J. D.

    1990-08-01

    Motion analysis studies require the precise tracking of reference objects in sequential scenes. In a typical situation, events of interest are captured at high frame rates using special cameras, and selected objects or targets are tracked on a frame by frame basis to provide necessary data for motion reconstruction. Tracking is usually done using manual methods which are slow and prone to error. A computer based image analysis system has been developed that performs tracking automatically. The objective of this work was to eliminate the bottleneck due to manual methods in high volume tracking applications such as the analysis of crash test films for the automotive industry. The system has proven to be successful in tracking standard fiducial targets and other objects in crash test scenes. Over 95 percent of target positions which could be located using manual methods can be tracked by the system, with a significant improvement in throughput over manual methods. Future work will focus on the tracking of clusters of targets and on tracking deformable objects such as airbags.

  4. 75 FR 72942 - Standard Instrument Approach Procedures, and Takeoff Minimums and Obstacle Departure Procedures...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-29

    ..., Takeoff Minimums and Obstacle DP, Amdt 3 Harvard, NE, Harvard State, RNAV (GPS) RWY 35, Orig Harvard, NE, Harvard State, Takeoff Minimums and Obstacle DP, Orig Harvard, NE, Harvard State, VOR/DME RNAV OR GPS RWY...

  5. Facilitators and obstacles in pre-hospital medical response to earthquakes: a qualitative study.

    PubMed

    Djalali, Ahmadreza; Khankeh, Hamidreza; Öhlén, Gunnar; Castrén, Maaret; Kurland, Lisa

    2011-05-16

    Earthquakes are renowned as being amongst the most dangerous and destructive types of natural disasters. Iran, a developing country in Asia, is prone to earthquakes and is ranked as one of the most vulnerable countries in the world in this respect. The medical response in disasters is accompanied by managerial, logistic, technical, and medical challenges being also the case in the Bam earthquake in Iran. Our objective was to explore the medical response to the Bam earthquake with specific emphasis on pre-hospital medical management during the first days. The study was performed in 2008; an interview based qualitative study using content analysis. We conducted nineteen interviews with experts and managers responsible for responding to the Bam earthquake, including pre-hospital emergency medical services, the Red Crescent, and Universities of Medical Sciences. The selection of participants was determined by using a purposeful sampling method. Sample size was given by data saturation. The pre-hospital medical service was divided into three categories; triage, emergency medical care and transportation, each category in turn was identified into facilitators and obstacles. The obstacles identified were absence of a structured disaster plan, absence of standardized medical teams, and shortage of resources. The army and skilled medical volunteers were identified as facilitators. The most compelling, and at the same time amenable obstacle, was the lack of a disaster management plan. It was evident that implementing a comprehensive plan would not only save lives but decrease suffering and enable an effective praxis of the available resources at pre-hospital and hospital levels.

  6. Facilitators and obstacles in pre-hospital medical response to earthquakes: a qualitative study

    PubMed Central

    2011-01-01

    Background Earthquakes are renowned as being amongst the most dangerous and destructive types of natural disasters. Iran, a developing country in Asia, is prone to earthquakes and is ranked as one of the most vulnerable countries in the world in this respect. The medical response in disasters is accompanied by managerial, logistic, technical, and medical challenges being also the case in the Bam earthquake in Iran. Our objective was to explore the medical response to the Bam earthquake with specific emphasis on pre-hospital medical management during the first days. Methods The study was performed in 2008; an interview based qualitative study using content analysis. We conducted nineteen interviews with experts and managers responsible for responding to the Bam earthquake, including pre-hospital emergency medical services, the Red Crescent, and Universities of Medical Sciences. The selection of participants was determined by using a purposeful sampling method. Sample size was given by data saturation. Results The pre-hospital medical service was divided into three categories; triage, emergency medical care and transportation, each category in turn was identified into facilitators and obstacles. The obstacles identified were absence of a structured disaster plan, absence of standardized medical teams, and shortage of resources. The army and skilled medical volunteers were identified as facilitators. Conclusions The most compelling, and at the same time amenable obstacle, was the lack of a disaster management plan. It was evident that implementing a comprehensive plan would not only save lives but decrease suffering and enable an effective praxis of the available resources at pre-hospital and hospital levels. PMID:21575233

  7. Energy dissipation by submarine obstacles during landslide impact on reservoir - potentially avoiding catastrophic dam collapse

    NASA Astrophysics Data System (ADS)

    Kafle, Jeevan; Kattel, Parameshwari; Mergili, Martin; Fischer, Jan-Thomas; Tuladhar, Bhadra Man; Pudasaini, Shiva P.

    2017-04-01

    Dense geophysical mass flows such as landslides, debris flows and debris avalanches may generate super tsunami waves as they impact water bodies such as the sea, hydraulic reservoirs or mountain lakes. Here, we apply a comprehensive and general two-phase, physical-mathematical mass flow model (Pudasaini, 2012) that consists of non-linear and hyperbolic-parabolic partial differential equations for mass and momentum balances, and present novel, high-resolution simulation results for two-phase flows, as a mixture of solid grains and viscous fluid, impacting fluid reservoirs with obstacles. The simulations demonstrate that due to the presence of different obstacles in the water body, the intense flow-obstacle-interaction dramatically reduces the flow momentum resulting in the rapid energy dissipation around the obstacles. With the increase of obstacle height overtopping decreases but, the deflection and capturing (holding) of solid mass increases. In addition, the submarine solid mass is captured by the multiple obstacles and the moving mass decreases both in amount and speed as each obstacle causes the flow to deflect into two streams and also captures a portion of it. This results in distinct tsunami and submarine flow dynamics with multiple surface water and submarine debris waves. This novel approach can be implemented in open source GIS modelling framework r.avaflow, and be applied in hazard mitigation, prevention and relevant engineering or environmental tasks. This might be in particular for process chains, such as debris impacts in lakes and subsequent overtopping. So, as the complex flow-obstacle-interactions strongly and simultaneously dissipate huge energy at impact such installations potentially avoid great threat against the integrity of the dam. References: Pudasaini, S. P. (2012): A general two-phase debris flow model. J. Geophys. Res. 117, F03010, doi: 10.1029/ 2011JF002186.

  8. Object classification for obstacle avoidance

    NASA Astrophysics Data System (ADS)

    Regensburger, Uwe; Graefe, Volker

    1991-03-01

    Object recognition is necessary for any mobile robot operating autonomously in the real world. This paper discusses an object classifier based on a 2-D object model. Obstacle candidates are tracked and analyzed false alarms generated by the object detector are recognized and rejected. The methods have been implemented on a multi-processor system and tested in real-world experiments. They work reliably under favorable conditions but sometimes problems occur e. g. when objects contain many features (edges) or move in front of structured background.

  9. Age-Related Physical Changes Interfere With Judgments of Male Sexual Orientation From Faces.

    PubMed

    Tskhay, Konstantin O; Krendl, Anne C; Rule, Nicholas O

    2016-09-01

    Although studies have shown that sexual orientation can be judged from faces, this research has not considered how age-related differences in perceivers or targets affect such judgments. In the current work, we evaluated whether accuracy differed among young adults (YA) and older adults (OA) for young and old men's faces by recruiting a sample of YA and OA in the lab, a community sample of sexual minority men, and a sample of online participants. We found that OA and YA judged sexual orientation with similar accuracy. Perceptions of gender atypicality mediated the difference in judging older and younger targets' sexual orientation. Although participants used positive affect to correctly discern sexual orientation regardless of target age, perceptions of masculinity were valid only for judgments of YA. © 2016 by the Society for Personality and Social Psychology, Inc.

  10. Perceived orientation in physical and virtual environments: changes in perceived orientation as a function of idiothetic information available

    NASA Technical Reports Server (NTRS)

    Lathrop, William B.; Kaiser, Mary K.

    2002-01-01

    Two experiments examined perceived spatial orientation in a small environment as a function of experiencing that environment under three conditions: real-world, desktop-display (DD), and head-mounted display (HMD). Across the three conditions, participants acquired two targets located on a perimeter surrounding them, and attempted to remember the relative locations of the targets. Subsequently, participants were tested on how accurately and consistently they could point in the remembered direction of a previously seen target. Results showed that participants were significantly more consistent in the real-world and HMD conditions than in the DD condition. Further, it is shown that the advantages observed in the HMD and real-world conditions were not simply due to nonspatial response strategies. These results suggest that the additional idiothetic information afforded in the real-world and HMD conditions is useful for orientation purposes in our presented task domain. Our results are relevant to interface design issues concerning tasks that require spatial search, navigation, and visualization.

  11. Thermal activation of dislocations in large scale obstacle bypass

    NASA Astrophysics Data System (ADS)

    Sobie, Cameron; Capolungo, Laurent; McDowell, David L.; Martinez, Enrique

    2017-08-01

    Dislocation dynamics simulations have been used extensively to predict hardening caused by dislocation-obstacle interactions, including irradiation defect hardening in the athermal case. Incorporating the role of thermal energy on these interactions is possible with a framework provided by harmonic transition state theory (HTST) enabling direct access to thermally activated reaction rates using the Arrhenius equation, including rates of dislocation-obstacle bypass processes. Moving beyond unit dislocation-defect reactions to a representative environment containing a large number of defects requires coarse-graining the activation energy barriers of a population of obstacles into an effective energy barrier that accurately represents the large scale collective process. The work presented here investigates the relationship between unit dislocation-defect bypass processes and the distribution of activation energy barriers calculated for ensemble bypass processes. A significant difference between these cases is observed, which is attributed to the inherent cooperative nature of dislocation bypass processes. In addition to the dislocation-defect interaction, the morphology of the dislocation segments pinned to the defects play an important role on the activation energies for bypass. A phenomenological model for activation energy stress dependence is shown to describe well the effect of a distribution of activation energies, and a probabilistic activation energy model incorporating the stress distribution in a material is presented.

  12. Student Obstacles in Ratio and Proportion Learning

    NASA Astrophysics Data System (ADS)

    Andini, W.; Jupri, Al

    2017-02-01

    Ratio and proportion are mathematics topics that are learned in elementary school. In the learning process, teachers often found students who have difficulties in learning these topics. Analysing the difficulties on the topics is important for teachers, as an attempt to doa reflection of the learning process and as a reference in devising a learning plan, including for anticipation of the possibility of these barriers that might appear in the next learning process. This research used as the qualitative method, and involved 49 students of grade 5 and one teacher. From the analysis of the data, i.e., student test results and observation of the learning, we found some obstacles that faced by students, such as students confused in understanding about ratio and proportion topic, students found it difficult in completing the problem which have different contexts, the learning material of ratio and proportion topic that presented in textbooks are still partial (not depth), and the lack of ability of the teacher in creating problems.

  13. Focus for Area Development Analysis: Urban Orientation of Counties.

    ERIC Educational Resources Information Center

    Bluestone, Herman

    The orientation of counties to metropolitan systems and urban centers is identified by population density and percentage of urban population. This analytical framework differentiates 6 kinds of counties, ranging from most urban-oriented (group 1) to least urban-oriented (group 6). With this framework, it can be seen that the economic well-being of…

  14. Effects of soft interactions and bound mobility on diffusion in crowded environments: a model of sticky and slippery obstacles

    NASA Astrophysics Data System (ADS)

    Stefferson, Michael W.; Norris, Samantha L.; Vernerey, Franck J.; Betterton, Meredith D.; E Hough, Loren

    2017-08-01

    Crowded environments modify the diffusion of macromolecules, generally slowing their movement and inducing transient anomalous subdiffusion. The presence of obstacles also modifies the kinetics and equilibrium behavior of tracers. While previous theoretical studies of particle diffusion have typically assumed either impenetrable obstacles or binding interactions that immobilize the particle, in many cellular contexts bound particles remain mobile. Examples include membrane proteins or lipids with some entry and diffusion within lipid domains and proteins that can enter into membraneless organelles or compartments such as the nucleolus. Using a lattice model, we studied the diffusive movement of tracer particles which bind to soft obstacles, allowing tracers and obstacles to occupy the same lattice site. For sticky obstacles, bound tracer particles are immobile, while for slippery obstacles, bound tracers can hop without penalty to adjacent obstacles. In both models, binding significantly alters tracer motion. The type and degree of motion while bound is a key determinant of the tracer mobility: slippery obstacles can allow nearly unhindered diffusion, even at high obstacle filling fraction. To mimic compartmentalization in a cell, we examined how obstacle size and a range of bound diffusion coefficients affect tracer dynamics. The behavior of the model is similar in two and three spatial dimensions. Our work has implications for protein movement and interactions within cells.

  15. Shifting from Sexual Orientation to Relational Orientation: A Discursive Move with Theoretical and Pedagogical Benefits

    ERIC Educational Resources Information Center

    Greenfield, Derek

    2005-01-01

    In this article, I argue that the term "sexual orientation" serves as a mechanism for preserving heteronormative hegemony, with the proposed concept of "relational orientation" encouraging a richer theoretical analysis of the factors that shape identity. The relational orientation approach establishes a more holistic representation of lesbian,…

  16. A Compact Magnetic Field-Based Obstacle Detection and Avoidance System for Miniature Spherical Robots.

    PubMed

    Wu, Fang; Vibhute, Akash; Soh, Gim Song; Wood, Kristin L; Foong, Shaohui

    2017-05-28

    Due to their efficient locomotion and natural tolerance to hazardous environments, spherical robots have wide applications in security surveillance, exploration of unknown territory and emergency response. Numerous studies have been conducted on the driving mechanism, motion planning and trajectory tracking methods of spherical robots, yet very limited studies have been conducted regarding the obstacle avoidance capability of spherical robots. Most of the existing spherical robots rely on the "hit and run" technique, which has been argued to be a reasonable strategy because spherical robots have an inherent ability to recover from collisions. Without protruding components, they will not become stuck and can simply roll back after running into bstacles. However, for small scale spherical robots that contain sensitive surveillance sensors and cannot afford to utilize heavy protective shells, the absence of obstacle avoidance solutions would leave the robot at the mercy of potentially dangerous obstacles. In this paper, a compact magnetic field-based obstacle detection and avoidance system has been developed for miniature spherical robots. It utilizes a passive magnetic field so that the system is both compact and power efficient. The proposed system can detect not only the presence, but also the approaching direction of a ferromagnetic obstacle, therefore, an intelligent avoidance behavior can be generated by adapting the trajectory tracking method with the detection information. Design optimization is conducted to enhance the obstacle detection performance and detailed avoidance strategies are devised. Experimental results are also presented for validation purposes.

  17. Control of vertical posture while elevating one foot to avoid a real or virtual obstacle.

    PubMed

    Ida, Hirofumi; Mohapatra, Sambit; Aruin, Alexander

    2017-06-01

    The purpose of this study is to investigate the control of vertical posture during obstacle avoidance in a real versus a virtual reality (VR) environment. Ten healthy participants stood upright and lifted one leg to avoid colliding with a real obstacle sliding on the floor toward a participant and with its virtual image. Virtual obstacles were delivered by a head mounted display (HMD) or a 3D projector. The acceleration of the foot, center of pressure, and electrical activity of the leg and trunk muscles were measured and analyzed during the time intervals typical for early postural adjustments (EPAs), anticipatory postural adjustments (APAs), and compensatory postural adjustments (CPAs). The results showed that the peak acceleration of foot elevation in the HMD condition decreased significantly when compared with that of the real and 3D projector conditions. Reduced activity of the leg and trunk muscles was seen when dealing with virtual obstacles (HMD and 3D projector) as compared with that seen when dealing with real obstacles. These effects were more pronounced during APAs and CPAs. The onsets of muscle activities in the supporting limb were seen during EPAs and APAs. The observed modulation of muscle activity and altered patterns of movement seen while avoiding a virtual obstacle should be considered when designing virtual rehabilitation protocols.

  18. Creation of a Mental Health Treatment Fears and Obstacles Inventory for College Students

    ERIC Educational Resources Information Center

    Park, Heather L.; Attenweiler, William J.; Rieck, Stacey M.

    2012-01-01

    This project concerned the creation of an inventory for college students of treatment fears and obstacles to seeking mental health services. Unlike previous research, undergraduate participants generated a pool of items to measure fears of and obstacles to seeking services. Subsequent rational and statistical refinement resulted in a 29-item scale…

  19. Training toddlers seated on mobile robots to drive indoors amidst obstacles.

    PubMed

    Chen, Xi; Ragonesi, Christina; Galloway, James C; Agrawal, Sunil K

    2011-06-01

    Mobility is a causal factor in development. Children with mobility impairments may rely upon power mobility for independence and thus require advanced driving skills to function independently. Our previous studies show that while infants can learn to drive directly to a goal using conventional joysticks in several months of training, they are unable in this timeframe to acquire the advanced skill to avoid obstacles while driving. Without adequate driving training, children are unable to explore the environment safely, the consequences of which may in turn increase their risk for developmental delay. The goal of this research therefore is to train children seated on mobile robots to purposefully and safely drive indoors. In this paper, we present results where ten typically-developing toddlers are trained to drive a robot within an obstacle course. We also report a case study with a toddler with spina-bifida who cannot independently walk. Using algorithms based on artificial potential fields to avoid obstacles, we create force field on the joystick that trains the children to navigate while avoiding obstacles. In this "assist-as-needed" approach, if the child steers the joystick outside a force tunnel centered on the desired direction, the driver experiences a bias force on the hand. Our results suggest that the use of a force-feedback joystick may yield faster learning than the use of a conventional joystick.

  20. IDL Object Oriented Software for Hinode/XRT Image Analysis

    NASA Astrophysics Data System (ADS)

    Higgins, P. A.; Gallagher, P. T.

    2008-09-01

    We have developed a set of object oriented IDL routines that enable users to search, download and analyse images from the X-Ray Telescope (XRT) on-board Hinode. In this paper, we give specific examples of how the object can be used and how multi-instrument data analysis can be performed. The XRT object is a highly versatile and powerful IDL object, which will prove to be a useful tool for solar researchers. This software utilizes the generic Framework object available within the GEN branch of SolarSoft.

  1. Introduction of frictional and turning function for pedestrian outflow with an obstacle.

    PubMed

    Yanagisawa, Daichi; Kimura, Ayako; Tomoeda, Akiyasu; Nishi, Ryosuke; Suma, Yushi; Ohtsuka, Kazumichi; Nishinari, Katsuhiro

    2009-09-01

    In this paper, two important factors which affect the pedestrian outflow at a bottleneck significantly are studied in detail to analyze the effect of an obstacle setup in front of an exit. One is a conflict at an exit when pedestrians evacuate from a room. We use floor field model for simulating such behavior, which is a well-studied pedestrian model using cellular automata. The conflicts have been taken into account by the friction parameter. However, the friction parameter so far is a constant and does not depend on the number of the pedestrians conflicting at the same time. Thus, we have improved the friction parameter by the frictional function, which is a function of the number of the pedestrians involved in the conflict. Second, we have presented the cost of turning of pedestrians at the exit. Since pedestrians have inertia, their walking speeds decrease when they turn and the pedestrian outflow decreases. The validity of the extended model, which includes the frictional function and the turning function, is supported by the comparison of a mean-field theory and real experiments. We have observed that the pedestrian flow increases when we put an obstacle in front of an exit in our real experiments. The analytical results clearly explains the mechanism of the effect of the obstacle, i.e., the obstacle blocks pedestrians moving to the exit and decreases the average number of pedestrians involved in the conflict. We have also found that an obstacle works more effectively when we shift it from the center since pedestrians go through the exit with less turning.

  2. Automatic attentional orienting to other people's gaze in schizophrenia.

    PubMed

    Langdon, Robyn; Seymour, Kiley; Williams, Tracey; Ward, Philip B

    2017-08-01

    Explicit tests of social cognition have revealed pervasive deficits in schizophrenia. Less is known of automatic social cognition in schizophrenia. We used a spatial orienting task to investigate automatic shifts of attention cued by another person's eye gaze in 29 patients and 28 controls. Central photographic images of a face with eyes shifted left or right, or looking straight ahead, preceded targets that appeared left or right of the cue. To examine automatic effects, cue direction was non-predictive of target location. Cue-target intervals were 100, 300, and 800 ms. In non-social control trials, arrows replaced eye-gaze cues. Both groups showed automatic attentional orienting indexed by faster reaction times (RTs) when arrows were congruent with target location across all cue-target intervals. Similar congruency effects were seen for eye-shift cues at 300 and 800 ms intervals, but patients showed significantly larger congruency effects at 800 ms, which were driven by delayed responses to incongruent target locations. At short 100-ms cue-target intervals, neither group showed faster RTs for congruent than for incongruent eye-shift cues, but patients were significantly slower to detect targets after direct-gaze cues. These findings conflict with previous studies using schematic line drawings of eye-shifts that have found automatic attentional orienting to be reduced in schizophrenia. Instead, our data indicate that patients display abnormalities in responding to gaze direction at various stages of gaze processing-reflected by a stronger preferential capture of attention by another person's direct eye contact at initial stages of gaze processing and difficulties disengaging from a gazed-at location once shared attention is established.

  3. Error analysis of the crystal orientations obtained by the dictionary approach to EBSD indexing.

    PubMed

    Ram, Farangis; Wright, Stuart; Singh, Saransh; De Graef, Marc

    2017-10-01

    The efficacy of the dictionary approach to Electron Back-Scatter Diffraction (EBSD) indexing was evaluated through the analysis of the error in the retrieved crystal orientations. EBSPs simulated by the Callahan-De Graef forward model were used for this purpose. Patterns were noised, distorted, and binned prior to dictionary indexing. Patterns with a high level of noise, with optical distortions, and with a 25 × 25 pixel size, when the error in projection center was 0.7% of the pattern width and the error in specimen tilt was 0.8°, were indexed with a 0.8° mean error in orientation. The same patterns, but 60 × 60 pixel in size, were indexed by the standard 2D Hough transform based approach with almost the same orientation accuracy. Optimal detection parameters in the Hough space were obtained by minimizing the orientation error. It was shown that if the error in detector geometry can be reduced to 0.1% in projection center and 0.1° in specimen tilt, the dictionary approach can retrieve a crystal orientation with a 0.2° accuracy. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Manipulating the fidelity of lower extremity visual feedback to identify obstacle negotiation strategies in immersive virtual reality.

    PubMed

    Kim, Aram; Zhou, Zixuan; Kretch, Kari S; Finley, James M

    2017-07-01

    The ability to successfully navigate obstacles in our environment requires integration of visual information about the environment with estimates of our body's state. Previous studies have used partial occlusion of the visual field to explore how information about the body and impending obstacles are integrated to mediate a successful clearance strategy. However, because these manipulations often remove information about both the body and obstacle, it remains to be seen how information about the lower extremities alone is utilized during obstacle crossing. Here, we used an immersive virtual reality (VR) interface to explore how visual feedback of the lower extremities influences obstacle crossing performance. Participants wore a head-mounted display while walking on treadmill and were instructed to step over obstacles in a virtual corridor in four different feedback trials. The trials involved: (1) No visual feedback of the lower extremities, (2) an endpoint-only model, (3) a link-segment model, and (4) a volumetric multi-segment model. We found that the volumetric model improved success rate, placed their trailing foot before crossing and leading foot after crossing more consistently, and placed their leading foot closer to the obstacle after crossing compared to no model. This knowledge is critical for the design of obstacle negotiation tasks in immersive virtual environments as it may provide information about the fidelity necessary to reproduce ecologically valid practice environments.

  5. Effects of overweight and obese body mass on motor planning and motor skills during obstacle crossing in children.

    PubMed

    Gill, Simone V; Hung, Ya-Ching

    2014-01-01

    Little is known about how obesity relates to motor planning and skills during functional tasks. We collected 3-D kinematics and kinetics as normal weight (n=10) and overweight/obese (n=12) children walked on flat ground and as they crossed low, medium, and high obstacles. We investigated if motor planning and motor skill impairments were evident during obstacle crossing. Baseline conditions showed no group differences (all ps>.05). Increased toe clearance was found on low obstacles (p=.01) for the overweight/obese group and on high obstacles (p=.01) for the normal weight group. With the crossing leg, the overweight/obese group had larger hip abduction angles (p=.01) and medial ground reaction forces (p=.006) on high obstacles and high anterior ground reaction forces on low obstacles (p=.001). With the trailing leg, overweight/obese children had higher vertical ground reaction forces on high obstacles (p=.005) and higher knee angles (p=.01) and anterior acceleration in the center of mass (p=.01) on low obstacles. These findings suggest that differences in motor planning and skills in overweight/obese children may be more apparent during functional activities. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Navigation integrity monitoring and obstacle detection for enhanced-vision systems

    NASA Astrophysics Data System (ADS)

    Korn, Bernd; Doehler, Hans-Ullrich; Hecker, Peter

    2001-08-01

    Typically, Enhanced Vision (EV) systems consist of two main parts, sensor vision and synthetic vision. Synthetic vision usually generates a virtual out-the-window view using databases and accurate navigation data, e. g. provided by differential GPS (DGPS). The reliability of the synthetic vision highly depends on both, the accuracy of the used database and the integrity of the navigation data. But especially in GPS based systems, the integrity of the navigation can't be guaranteed. Furthermore, only objects that are stored in the database can be displayed to the pilot. Consequently, unexpected obstacles are invisible and this might cause severe problems. Therefore, additional information has to be extracted from sensor data to overcome these problems. In particular, the sensor data analysis has to identify obstacles and has to monitor the integrity of databases and navigation. Furthermore, if a lack of integrity arises, navigation data, e.g. the relative position of runway and aircraft, has to be extracted directly from the sensor data. The main contribution of this paper is about the realization of these three sensor data analysis tasks within our EV system, which uses the HiVision 35 GHz MMW radar of EADS, Ulm as the primary EV sensor. For the integrity monitoring, objects extracted from radar images are registered with both database objects and objects (e. g. other aircrafts) transmitted via data link. This results in a classification into known and unknown radar image objects and consequently, in a validation of the integrity of database and navigation. Furthermore, special runway structures are searched for in the radar image where they should appear. The outcome of this runway check contributes to the integrity analysis, too. Concurrent to this investigation a radar image based navigation is performed without using neither precision navigation nor detailed database information to determine the aircraft's position relative to the runway. The performance of our

  7. Health promotion--the rationale and the obstacles in workplaces with different employment and financial soundness.

    PubMed

    Puchalski, Krzysztof; Korzeniowska, Elzbieta

    2013-01-01

    This paper presents the prevalence of health promotion in workplaces in Poland. It characterises the undertaken ac tions, their rationale and perceived obstacles. It analyses the diversity of these phenomena in the companies of different financial soundness and level of employment. The study was conducted with the use of Computer Assisted Telephone Interview in 2010 on the representative national sample of 1002 workplaces hiring more than 50 employees. The data was compared with the results of the survey conducted in 2006, with the use of a Paper and Pencil interview on 611 similar companies. Both studies have shown that 40% of the companies are concerned about their employees' health to a greater extent than they are obliged to by the law. At the same time, more than 80% of the companies have been introducing various modifications and health-oriented actions without definite health intentions. Most companies improve their physical working environment, organise/sponsor medical services, sports activities and try to reduce stress and smoking. Managers have increased their awareness of business benefits re ceived from health promotion. They have displayed more personal involvement in health promotion implementation. The most often mentioned obstacles have included limited financial resources and little interest of employees regarding health issues. The larger and wealthier the company is, the more often health promotion in the company is performed. Such a company is more convinced about an increase in its activities and has more reasons to care about health. Unequal access to health promotion of wor kers in different companies may contribute to an increase in health inequalities in the working population.

  8. Orientation of liquid crystalline blue phases on unidirectionally orienting surfaces

    NASA Astrophysics Data System (ADS)

    Takahashi, Misaki; Ohkawa, Takuma; Yoshida, Hiroyuki; Fukuda, Jun-ichi; Kikuchi, Hirostugu; Ozaki, Masanori

    2018-03-01

    Liquid crystalline cholesteric blue phases (BPs) continue to attract interest due to their fast response times and quasi-polarization-independent phase modulation capabilities. Various approaches have recently been proposed to control the crystal orientation of BPs on substrates; however, their basic orientation properties on standard, unidirectionally orienting alignment layers have not been investigated in detail. Through analysis of the azimuthal orientation of Kossel diagrams, we study the 3D crystal orientation of a BP material—with a phase sequence of cholesteric, BP I, and BP II—on unidirectionally orienting surfaces prepared using two methods: rubbing and photoalignment. BP II grown from the isotropic phase is sensitive to surface conditions, with different crystal planes orienting on the two substrates. On the other hand, strong thermal hysteresis is observed in BPs grown through a different liquid crystal phase, implying that the preceding structure determines the orientation. More specifically, the BP II-I transition is accompanied by a rotation of the crystal such that the crystal direction defined by certain low-value Miller indices transform into different directions, and within the allowed rotations, different azimuthal configurations are obtained in the same cell depending on the thermal process. Our findings demonstrate that, for the alignment control of BPs, the thermal process is as important as the properties of the alignment layer.

  9. Laminar CuO-water nano-fluid flow and heat transfer in a backward-facing step with and without obstacle

    NASA Astrophysics Data System (ADS)

    Togun, Hussein

    2016-03-01

    This paper presents a numerical investigate on CuO-water nano-fluid and heat transfer in a backward-facing step with and without obstacle. The range of Reynolds number varied from 75 to 225 with volume fraction on CuO nanoparticles varied from 1 to 4 % at constant heat flux was investigated. Continuity, momentum, and energy equations with finite volume method in two dimensions were employed. Four different configurations of backward-facing step (without obstacle, with obstacle of 1.5 mm, with obstacle of 3 mm, with obstacle of 4.5 mm) were considered to find the best thermal performance. The results show that the maximum augmentation in heat transfer was about 22 % for backward-facing step with obstacle of 4.5 mm and using CuO nanoparticles at Reynolds number of 225 compared with backward-facing step without obstacle. It is also observed that increase in size of recirculation region with increase of height obstacle on the channel wall has remarkable effect on thermal performance. The results also found that increases in Reynolds number, height obstacle, and volume fractions of CuO nanoparticles lead to increase of pressure drop.

  10. Neuroepigenomics: Resources, Obstacles, and Opportunities

    PubMed Central

    Satterlee, John S.; Beckel-Mitchener, Andrea; Little, Roger; Procaccini, Dena; Rutter, Joni L.; Lossie, Amy C.

    2014-01-01

    Long-lived post-mitotic cells, such as the majority of human neurons, must respond effectively to ongoing changes in neuronal stimulation or microenvironmental cues through transcriptional and epigenomic regulation of gene expression. The role of epigenomic regulation in neuronal function is of fundamental interest to the neuroscience community, as these types of studies have transformed our understanding of gene regulation in post-mitotic cells. This perspective article highlights many of the resources available to researchers interested in neuroepigenomic investigations and discusses some of the current obstacles and opportunities in neuroepigenomics. PMID:25722961

  11. Learn to Avoid or Overcome Leadership Obstacles

    ERIC Educational Resources Information Center

    D'Auria, John

    2015-01-01

    Leadership is increasingly recognized as an important factor in moving schools forward, yet we have been relatively random in how we prepare and support them. Four obstacles often block or diminish their effectiveness. Avoiding or overcoming each of these requires an underlying set of skills and knowledge that we believe can be learned and…

  12. Understanding the Association Between School Climate and Future Orientation.

    PubMed

    Lindstrom Johnson, Sarah; Pas, Elise; Bradshaw, Catherine P

    2016-08-01

    Promoting students' future orientation is inherently a goal of the educational system. Recently, it has received more explicit attention given the increased focus on career readiness. This study aimed to examine the association between school climate and adolescents' report of future orientation using data from youth (N = 27,698; 49.4 % female) across 58 high schools. Three-level hierarchical linear models indicated that perceptions of available emotional and service supports, rules and consequences, and parent engagement were positively related to adolescents' future orientation. Additionally, the school-level average future orientation was significantly related to individuals' future orientation, indicating a potential influence of contextual effects on this construct. Taken together, these findings suggest that interventions targeting school climate may hold promise for promoting future orientation.

  13. Portuguese primary school children's conceptions about digestion: identification of learning obstacles

    NASA Astrophysics Data System (ADS)

    Silva, Rui Graça; Lima, Nelson; Coquet, Eduarda; Clément, Pierre

    2004-09-01

    A cross-sectional study of Portuguese primary school pupils' conceptions on digestion and the digestive tract was carried out before and after teaching this topic. Pupils of the prior four school years (5/6 to 9/10 year old) drew what happens to a cookie inside their body. In some cases they also wrote a short text or were interviewed. To identify their level of graphic development, they produced a free-hand drawing. The main conceptual changes in explaining digestion were strongly linked to teaching. Children's previous conceptions were not epistemological obstacles to learning about digestion. The main obstacles were of didactical origin, as images of primary school books do not represent (i) the path of food from the intestine into the blood, (associated to the epistemological obstacle of the permeability of the gut wall); (ii) a clear continuous tract from stomach to anus, which causes a specific confusion at the intestine level.

  14. A Method on Dynamic Path Planning for Robotic Manipulator Autonomous Obstacle Avoidance Based on an Improved RRT Algorithm.

    PubMed

    Wei, Kun; Ren, Bingyin

    2018-02-13

    In a future intelligent factory, a robotic manipulator must work efficiently and safely in a Human-Robot collaborative and dynamic unstructured environment. Autonomous path planning is the most important issue which must be resolved first in the process of improving robotic manipulator intelligence. Among the path-planning methods, the Rapidly Exploring Random Tree (RRT) algorithm based on random sampling has been widely applied in dynamic path planning for a high-dimensional robotic manipulator, especially in a complex environment because of its probability completeness, perfect expansion, and fast exploring speed over other planning methods. However, the existing RRT algorithm has a limitation in path planning for a robotic manipulator in a dynamic unstructured environment. Therefore, an autonomous obstacle avoidance dynamic path-planning method for a robotic manipulator based on an improved RRT algorithm, called Smoothly RRT (S-RRT), is proposed. This method that targets a directional node extends and can increase the sampling speed and efficiency of RRT dramatically. A path optimization strategy based on the maximum curvature constraint is presented to generate a smooth and curved continuous executable path for a robotic manipulator. Finally, the correctness, effectiveness, and practicability of the proposed method are demonstrated and validated via a MATLAB static simulation and a Robot Operating System (ROS) dynamic simulation environment as well as a real autonomous obstacle avoidance experiment in a dynamic unstructured environment for a robotic manipulator. The proposed method not only provides great practical engineering significance for a robotic manipulator's obstacle avoidance in an intelligent factory, but also theoretical reference value for other type of robots' path planning.

  15. Longitudinal kinematic and kinetic adaptations to obstacle crossing in recent lower limb amputees.

    PubMed

    Barnett, Cleveland T; Polman, Remco C J; Vanicek, Natalie

    2014-12-01

    Obstacle crossing is an important activity of daily living, necessary to avoid tripping or falling, although it is not fully understood how transtibial amputees adapt to performing this activity of daily living following discharge from rehabilitation. The objective of this study was to investigate the longitudinal adaptations in obstacle crossing in transtibial amputees post-discharge from rehabilitation. Longitudinal repeated measures. Seven unilateral transtibial amputees crossed an obstacle 0.1m high positioned along a walkway while kinematic and kinetic data were recorded at 1, 3 and 6 months post-discharge. At 6 months post-discharge, walking velocity had increased (0.17 m.s(-1)) with most participants self-selecting an intact lead limb preference. During swing phase, peak knee flexion (p = 0.03) and peak knee power absorption (K4; p = 0.01) were greater with an intact versus affected lead limb preference. Having crossed the obstacle, intact limb peak ankle power generation in pre-swing (A2; p = 0.01) and knee power absorption (K3; p = 0.05) during stance phase were greater when compared to the affected limb. Obstacle crossing improved, although a greater reliance on intact limb function was highlighted. Results suggested that further improvements to locomotor performance may be obtained by increasing affected limb knee range of motion and concentric and eccentric strength of the knee extensors and flexors. The novel objective data from this study establish an understanding of how recent transtibial amputees adapt to performing obstacle crossing following discharge from rehabilitation. This allows for evidence-based clinical interventions to be developed, aimed at optimising biomechanical function, thus improving overall locomotor performance and perhaps subsequent quality of life. © The International Society for Prosthetics and Orthotics 2013.

  16. An Object Oriented Analysis Method for Ada and Embedded Systems

    DTIC Science & Technology

    1989-12-01

    expansion of the paradligm from the coding anld desiningactivities into the earlier activity of reurmnsalyi.Ts hpl, begins by discussing the application of...response time: 0.1 seconds.I Step le: Identify Known Restrictions on the Software.I " The cruise control system object code must fit within 16K of mem- orv...application of object-oriented techniques to the coding and desigll phases of the life cycle, as well as various approaches to requirements analysis. 3

  17. A Landscape Analysis to Understand Orientation of Honey Bee (Hymenoptera: Apidae) Drones in Puerto Rico.

    PubMed

    Galindo-Cardona, A; Monmany, A C; Diaz, G; Giray, T

    2015-08-01

    Honey bees [Apis mellifera L. (Apidae, Hymenoptera)] show spatial learning behavior or orientation, in which animals make use of structured home ranges for their daily activities. Worker (female) orientation has been studied more extensively than drone (male) orientation. Given the extensive and large flight range of drones as part of their reproductive biology, the study of drone orientation may provide new insight on landscape features important for orientation. We report the return rate and orientation of drones released at three distances (1, 2, and 4 km) and at the four cardinal points from an apiary located in Gurabo, Puerto Rico. We used high-resolution aerial photographs to describe landscape characteristics at the releasing sites and at the apiary. Analyses of variance were used to test significance among returning times from different distances and directions. A principal components analysis was used to describe the landscape at the releasing sites and generalized linear models were used to identify landscape characteristics that influenced the returning times of drones. Our results showed for the first time that drones are able to return from as far as 4 km from the colony. Distance to drone congregation area, orientation, and tree lines were the most important landscape characteristics influencing drone return rate. We discuss the role of landscape in drone orientation. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Flight data acquisition methodology for validation of passive ranging algorithms for obstacle avoidance

    NASA Technical Reports Server (NTRS)

    Smith, Phillip N.

    1990-01-01

    The automation of low-altitude rotorcraft flight depends on the ability to detect, locate, and navigate around obstacles lying in the rotorcraft's intended flightpath. Computer vision techniques provide a passive method of obstacle detection and range estimation, for obstacle avoidance. Several algorithms based on computer vision methods have been developed for this purpose using laboratory data; however, further development and validation of candidate algorithms require data collected from rotorcraft flight. A data base containing low-altitude imagery augmented with the rotorcraft and sensor parameters required for passive range estimation is not readily available. Here, the emphasis is on the methodology used to develop such a data base from flight-test data consisting of imagery, rotorcraft and sensor parameters, and ground-truth range measurements. As part of the data preparation, a technique for obtaining the sensor calibration parameters is described. The data base will enable the further development of algorithms for computer vision-based obstacle detection and passive range estimation, as well as provide a benchmark for verification of range estimates against ground-truth measurements.

  19. Orientation perception in Williams Syndrome: discrimination and integration

    PubMed Central

    Palomares, Melanie; Landau, Barbara; Egeth, Howard

    2009-01-01

    Williams Syndrome (WS) is a rare neurodevelopmental disorder, which stems from a genetic deletion on chromosome 7 that causes a profound weakness in visuospatial cognition. Our current study explores how orientation perception may contribute to the visuospatial deficits in WS. In Experiment 1, we found that WS individuals and normal 3-4 year olds had similar orientation discrimination thresholds and had similar prevalence of mirror-reversal errors for diagonal targets (±45 deg). In Experiment 2, we asked whether this immaturity in orientation discrimination would also be reflected in a task requiring integration of oriented elements. We found that sensitivities of WS individuals for detecting orientation-defined contours were higher than sensitivities of normal 3-4 year olds, and were not significantly different from sensitivities of normal adults. Together, these results suggest that orientation discrimination and orientation integration have different maturational trajectories in normal development and different susceptibilities to damage in WS, which may reflect largely separate visuospatial mechanisms. PMID:19231058

  20. Initiating Formal Requirements Specifications with Object-Oriented Models

    NASA Technical Reports Server (NTRS)

    Ampo, Yoko; Lutz, Robyn R.

    1994-01-01

    This paper reports results of an investigation into the suitability of object-oriented models as an initial step in developing formal specifications. The requirements for two critical system-level software modules were used as target applications. It was found that creating object-oriented diagrams prior to formally specifying the requirements enhanced the accuracy of the initial formal specifications and reduced the effort required to produce them. However, the formal specifications incorporated some information not found in the object-oriented diagrams, such as higher-level strategy or goals of the software.