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Sample records for subjects performed grasping

  1. Mode of grasp, materials, and grooved chopstick tip on gripping performance and evaluation.

    Science.gov (United States)

    Ho, Cheng-Pin; Wu, Swei-Pi

    2006-02-01

    This study evaluated the effects of the mode of grasping, chopstick materials, and the groove of the chopstick-tip on gripping performance of 32 participants, among whom 16 were accustomed to using chopsticks with a pliers-grasping mode and the other 16 with a scissors-grasping mode. Based on a random sequence, 8 kinds of chopsticks with different combinations (materials: bamboo, wood, plastic, and stainless steel, with and without grooves in the chopstick-tip) were used to carry out the action of gripping two different objects (peanuts and longan). The time to finish gripping 50 pieces of peanut and longan, the number which fell on the table when gripping, the subjective effort and the subjective preference were measures of efficiency of pinching for 8 kinds of chopsticks. Analysis showed that chopstick materials significantly affect time of gripping. The large object (such as longan) could be gripped more easily with the pliers-grasping mode or gripped with the grooved chopstick-tip. However, for small objects (such as peanuts), there was no significant difference in performance whether the chopstick-tip was grooved or not. A combination of bamboo chopsticks with grooved tips used with a pliers-grasping seem preferrable for more favorable gripping performance.

  2. Electrotactile feedback improves performance and facilitates learning in the routine grasping task

    Directory of Open Access Journals (Sweden)

    Milica Isaković

    2016-06-01

    Full Text Available Aim of this study was to investigate the feasibility of electrotactile feedback in closed loop training of force control during the routine grasping task. The feedback was provided using an array electrode and a simple six-level spatial coding, and the experiment was conducted in three amputee subjects. The psychometric tests confirmed that the subjects could perceive and interpret the electrotactile feedback with a high success rate. The subjects performed the routine grasping task comprising 4 blocks of 60 grasping trials. In each trial, the subjects employed feedforward control to close the hand and produce the desired grasping force (four levels. First (baseline and the last (validation session were performed in open loop, while the second and the third session (training included electrotactile feedback. The obtained results confirmed that using the feedback improved the accuracy and precision of the force control. In addition, the subjects performed significantly better in the validation vs. baseline session, therefore suggesting that electrotactile feedback can be used for learning and training of myoelectric control.

  3. Blending of brain-machine interface and vision-guided autonomous robotics improves neuroprosthetic arm performance during grasping.

    Science.gov (United States)

    Downey, John E; Weiss, Jeffrey M; Muelling, Katharina; Venkatraman, Arun; Valois, Jean-Sebastien; Hebert, Martial; Bagnell, J Andrew; Schwartz, Andrew B; Collinger, Jennifer L

    2016-03-18

    Recent studies have shown that brain-machine interfaces (BMIs) offer great potential for restoring upper limb function. However, grasping objects is a complicated task and the signals extracted from the brain may not always be capable of driving these movements reliably. Vision-guided robotic assistance is one possible way to improve BMI performance. We describe a method of shared control where the user controls a prosthetic arm using a BMI and receives assistance with positioning the hand when it approaches an object. Two human subjects with tetraplegia used a robotic arm to complete object transport tasks with and without shared control. The shared control system was designed to provide a balance between BMI-derived intention and computer assistance. An autonomous robotic grasping system identified and tracked objects and defined stable grasp positions for these objects. The system identified when the user intended to interact with an object based on the BMI-controlled movements of the robotic arm. Using shared control, BMI controlled movements and autonomous grasping commands were blended to ensure secure grasps. Both subjects were more successful on object transfer tasks when using shared control compared to BMI control alone. Movements made using shared control were more accurate, more efficient, and less difficult. One participant attempted a task with multiple objects and successfully lifted one of two closely spaced objects in 92 % of trials, demonstrating the potential for users to accurately execute their intention while using shared control. Integration of BMI control with vision-guided robotic assistance led to improved performance on object transfer tasks. Providing assistance while maintaining generalizability will make BMI systems more attractive to potential users. NCT01364480 and NCT01894802 .

  4. Grasp force control in telemanipulation

    Science.gov (United States)

    Wiker, Steven F.; Duffie, Neil A.

    1992-01-01

    This paper presents two experiments which focus upon the issue of grasp force control in telemanipulation. The first experiment examines the ability to control and stabilize master-controller grasp force during a 30-s compensatory tracking task under different levels of master controller digit mass, friction, and backlash. The second experiment explores the potential for substituting tactile feedback in lieu of direct force-feedback to gage and control remote grasp force. Results show that subjects were better able to control force when mass and friction levels were increased. Even when perceptual gains between tactile and direct force feedback displays were matched, force reflection produced better grasp control. The lack of backlash effects and improvements in performance with direct force reflection in comparison to tactile feedback are attributable to reflexive short-loop adjustment of grasp tension afforded by the muscle's length-tension control system. The criterion of acceptable operator performance, dependent upon both the quality of the transmission of control commands and feedback, and the response of the remote device, is discussed.

  5. Probabilistic Classification of Grasping Behaviours Using Visuo-Haptic Perception

    OpenAIRE

    S. Hosseini; Faria, Diego,; Lobo, Jorge; Dias, Jorge

    2012-01-01

    Part 9: Perceptional Systems; International audience; This paper presents a novel approach to visuo-haptic perception of grasping/manipulative tasks. The proposed approach is founded on a hierarchical Bayesian model which integrates the visual information with the haptic data to reach a reasonable percept of what is happening in grasping tasks. The primary goal of the approach is to identify what type of grasping behaviour is being performed by the human subject, and as a secondary goal, to s...

  6. Fast grasping of unknown objects using principal component analysis

    Science.gov (United States)

    Lei, Qujiang; Chen, Guangming; Wisse, Martijn

    2017-09-01

    Fast grasping of unknown objects has crucial impact on the efficiency of robot manipulation especially subjected to unfamiliar environments. In order to accelerate grasping speed of unknown objects, principal component analysis is utilized to direct the grasping process. In particular, a single-view partial point cloud is constructed and grasp candidates are allocated along the principal axis. Force balance optimization is employed to analyze possible graspable areas. The obtained graspable area with the minimal resultant force is the best zone for the final grasping execution. It is shown that an unknown object can be more quickly grasped provided that the component analysis principle axis is determined using single-view partial point cloud. To cope with the grasp uncertainty, robot motion is assisted to obtain a new viewpoint. Virtual exploration and experimental tests are carried out to verify this fast gasping algorithm. Both simulation and experimental tests demonstrated excellent performances based on the results of grasping a series of unknown objects. To minimize the grasping uncertainty, the merits of the robot hardware with two 3D cameras can be utilized to suffice the partial point cloud. As a result of utilizing the robot hardware, the grasping reliance is highly enhanced. Therefore, this research demonstrates practical significance for increasing grasping speed and thus increasing robot efficiency under unpredictable environments.

  7. Interlimb Transfer of Grasp Orientation is Asymmetrical

    Directory of Open Access Journals (Sweden)

    Victor Frak

    2006-01-01

    Full Text Available One the most fundamental aspects of the human motor system is the hemispheric asymmetry seen in behavioral specialization. Hemispheric dominance can be inferred by a contralateral hand preference in grasping. Few studies have considered grasp orientation in the context of manual lateralization and none has looked at grasp orientation with natural prehension. Thirty right-handed adults performed precision grasps of a cylinder using the thumb and index fingers, and the opposition axis (OA was defined as the line connecting these two contact points on the cylinder. Subjects made ten consecutive grasps with one hand (primary hand movements followed by ten grasps with the other hand (trailing movements. Differences between primary and trailing grasps revealed that each hemisphere is capable of programming the orientation of the OA and that primary movements with the right hand significantly influenced OA orientation of the trailing left hand. These results extend the hemispheric dominance of the left hemisphere to the final positions of fingers during prehension.

  8. Grasp force sensor for robotic hands

    Science.gov (United States)

    Scheinman, Victor D. (Inventor); Bejczy, Antal K. (Inventor); Primus, Howard C. (Inventor)

    1989-01-01

    A grasp force sensor for robotic hands is disclosed. A flexible block is located in the base of each claw through which the grasp force is exerted. The block yields minute parallelogram deflection when the claws are subjected to grasping forces. A parallelogram deflection closely resembles pure translational deflection, whereby the claws remain in substantial alignment with each other during grasping. Strain gauge transducers supply signals which provide precise knowledge of and control over grasp forces.

  9. Representation of motor habit in a sequence of repetitive reach and grasp movements performed by macaque monkeys: evidence for a contribution of the dorsolateral prefrontal cortex.

    Science.gov (United States)

    Kaeser, Mélanie; Wannier, Thierry; Brunet, Jean-François; Wyss, Alexander; Bloch, Jocelyne; Rouiller, Eric M

    2013-05-01

    In the context of an autologous cell transplantation study, a unilateral biopsy of cortical tissue was surgically performed from the right dorsolateral prefrontal cortex (dlPFC) in two intact adult macaque monkeys (dlPFC lesioned group), together with the implantation of a chronic chamber providing access to the left motor cortex. Three other monkeys were subjected to the same chronic chamber implantation, but without dlPFC biopsy (control group). All monkeys were initially trained to perform sequential manual dexterity tasks, requiring precision grip. The motor performance and the prehension's sequence (temporal order to grasp pellets from different spatial locations) were analysed for each hand. Following the surgery, transient and moderate deficits of manual dexterity per se occurred in both groups, indicating that they were not due to the dlPFC lesion (most likely related to the recording chamber implantation and/or general anaesthesia/medication). In contrast, changes of motor habit were observed for the sequential order of grasping in the two monkeys with dlPFC lesion only. The changes were more prominent in the monkey subjected to the largest lesion, supporting the notion of a specific effect of the dlPFC lesion on the motor habit of the monkeys. These observations are reminiscent of previous studies using conditional tasks with delay that have proposed a specialization of the dlPFC for visuo-spatial working memory, except that this is in a different context of "free-will", non-conditional manual dexterity task, without a component of working memory. Copyright © 2013. Published by Elsevier Ltd.

  10. Continuum robots and underactuated grasping

    Directory of Open Access Journals (Sweden)

    N. Giri

    2011-02-01

    Full Text Available We discuss the capabilities of continuum (continuous backbone robot structures in the performance of under-actuated grasping. Continuum robots offer the potential of robust grasps over a wide variety of object classes, due to their ability to adapt their shape to interact with the environment via non-local continuum contact conditions. Furthermore, this capability can be achieved with simple, low degree of freedom hardware. However, there are practical issues which currently limit the application of continuum robots to grasping. We discuss these issues and illustrate via an experimental continuum grasping case study.

    This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010, 19 August 2010, Montréal, Canada.

  11. Effects of unilateral motor cortex lesion on ipsilesional hand's reach and grasp performance in monkeys: relationship with recovery in the contralesional hand.

    Science.gov (United States)

    Kaeser, Mélanie; Wyss, Alexander F; Bashir, Shahid; Hamadjida, Adjia; Liu, Yu; Bloch, Jocelyne; Brunet, Jean-François; Belhaj-Saif, Abderaouf; Rouiller, Eric M

    2010-03-01

    Manual dexterity, a prerogative of primates, is under the control of the corticospinal (CS) tract. Because 90-95% of CS axons decussate, it is assumed that this control is exerted essentially on the contralateral hand. Consistently, unilateral lesion of the hand representation in the motor cortex is followed by a complete loss of dexterity of the contralesional hand. During the months following lesion, spontaneous recovery of manual dexterity takes place to a highly variable extent across subjects, although largely incomplete. In the present study, we tested the hypothesis that after a significant postlesion period, manual performance in the ipsilesional hand is correlated with the extent of functional recovery in the contralesional hand. To this aim, ten adult macaque monkeys were subjected to permanent unilateral motor cortex lesion. Monkeys' manual performance was assessed for each hand during several months postlesion, using our standard behavioral test (modified Brinkman board task) that provides a quantitative measure of reach and grasp ability. The ipsilesional hand's performance was found to be significantly enhanced over the long term (100-300 days postlesion) in six of ten monkeys, with the six exhibiting the best, though incomplete, recovery of the contralesional hand. There was a statistically significant correlation (r = 0.932; P < 0.001) between performance in the ipsilesional hand after significant postlesion period and the extent of recovery of the contralesional hand. This observation is interpreted in terms of different possible mechanisms of recovery, dependent on the recruitment of motor areas in the lesioned and/or intact hemispheres.

  12. Attentional focus of feedback for improving performance of reach-to-grasp after stroke: a randomised crossover study.

    Science.gov (United States)

    Durham, K F; Sackley, C M; Wright, C C; Wing, A M; Edwards, M G; van Vliet, P

    2014-06-01

    To investigate whether feedback inducing an external focus (EF) of attention (about movement effects) was more effective for retraining reach-to-grasp after stroke compared with feedback inducing an internal focus (IF) of attention (about body movement). It was predicted that inducing an EF of attention would be more beneficial to motor performance. Crossover trial where participants were assigned at random to two feedback order groups: IF followed by EF or EF followed by IF. Research laboratory. Forty-two people with upper limb impairment after stroke. Participants performed three reaching tasks: (A) reaching to grasp a jar; (B) placing a jar forwards on to a table; and (C) placing a jar on to a shelf. Ninety-six reaches were performed in total over one training session. Kinematic measures were collected using motion analysis. Primary outcome measures were movement duration, peak velocity of the wrist, size of peak aperture and peak elbow extension. Feedback inducing an EF of attention produced shorter movement durations {first feedback order group: IF mean 2.53 seconds [standard deviation (SD) 1.85]; EF mean 2.12 seconds (SD 1.63), mean difference 0.41 seconds; 95% confidence interval -0.68 to 1.5; P=0.008}, an increased percentage time to peak deceleration (P=0.01) when performing Task B, and an increased percentage time to peak velocity (P=0.039) when performing Task A compared with feedback inducing an IF of attention. However, an order effect was present whereby performance was improved if an EF of attention was preceded by an IF of attention. Feedback inducing an EF of attention may be of some benefit for improving motor performance of reaching in people with stroke in the short term; however, these results should be interpreted with caution. Further research using a randomised design is recommended to enable effects on motor learning to be assessed. Copyright © 2013 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

  13. Reduction in Cylindrical Grasp Strength Is Associated With Early Thumb Carpometacarpal Osteoarthritis.

    Science.gov (United States)

    Coughlan, Monica J; Bourdillon, Alexandra; Crisco, Joseph J; Kenney, Deborah; Weiss, Arnold-Peter; Ladd, Amy L

    2017-02-01

    Advanced thumb carpometacarpal (CMC) osteoarthritis (OA) can cause substantial impairment in hand function, from grasping heavy objects to fine manipulation of implements and tools. In the clinical setting, we commonly measure the grip strength of gross grasp with a hand dynamometer in patients with CMC OA. Cylindrical grasp, which requires more thumb contribution than gross grasp, is an alternative method of measuring grip strength and one that may provide insight into thumb-related conditions. Because gross grasp and cylindrical grasp use the thumb in different planes, measurement of gross grasp alone might underestimate impairment. Therefore, it is important to evaluate cylindrical grasp as well. To our knowledge this tool has yet to be examined in a population with early thumb CMC OA. (1) Is cylindrical grasp and gross grasp strength reduced in subjects with early thumb CMC OA compared with asymptomatic control subjects? (2) What is the association of cylindrical and gross grasp to thumb CMC OA after adjusting for age, sex, and hand dominance? We recruited 90 subjects with early symptomatic and radiographic thumb CMC OA and 38 asymptomatic healthy control subjects for this multisite controlled study. Demographic information, hand examination, comprehensive histories, plain film radiographs, and cylindrical and gross grasp strength data were collected on all 128 subjects. Mean grasp strength was calculated for cylindrical and gross grasp in the population with early CMC OA and the control population. A t-test was performed on cylindrical and gross grasp to evaluate the difference between the mean in the control and early CMC OA populations. We used separate linear regression models for the two types of grasp to further quantify the association of grasp with a diagnosis of early thumb CMC OA controlling for age, sex, and whether the subject used their dominant or nondominant hand in the study. Cylindrical grasp was weaker in the population with thumb CMC OA

  14. Visually guided grasping produces fMRI activation in dorsal but not ventral stream brain areas.

    Science.gov (United States)

    Culham, Jody C; Danckert, Stacey L; DeSouza, Joseph F X; Gati, Joseph S; Menon, Ravi S; Goodale, Melvyn A

    2003-11-01

    Although both reaching and grasping require transporting the hand to the object location, only grasping also requires processing of object shape, size and orientation to preshape the hand. Behavioural and neuropsychological evidence suggests that the object processing required for grasping relies on different neural substrates from those mediating object recognition. Specifically, whereas object recognition is believed to rely on structures in the ventral (occipitotemporal) stream, object grasping appears to rely on structures in the dorsal (occipitoparietal) stream. We used functional magnetic resonance imaging (fMRI) to determine whether grasping (compared to reaching) produced activation in dorsal areas, ventral areas, or both. We found greater activity for grasping than reaching in several regions, including anterior intraparietal (AIP) cortex. We also performed a standard object perception localizer (comparing intact vs. scrambled 2D object images) in the same subjects to identify the lateral occipital complex (LOC), a ventral stream area believed to play a critical role in object recognition. Although LOC was activated by the objects presented on both grasping and reaching trials, there was no greater activity for grasping compared to reaching. These results suggest that dorsal areas, including AIP, but not ventral areas such as LOC, play a fundamental role in computing object properties during grasping.

  15. Refining Grasp Affordance Models by Experience

    DEFF Research Database (Denmark)

    Detry, Renaud; Kraft, Dirk; Buch, Anders Glent

    2010-01-01

    with a visual model of the object they characterize. We explore a batch-oriented, experience-based learning paradigm where grasps sampled randomly from a density are performed, and an importance-sampling algorithm learns a refined density from the outcomes of these experiences. The first such learning cycle...... grasps. These affordances are represented probabilistically with grasp densities, which correspond to continuous density functions defined on the space of 6D gripper poses. A grasp density characterizes an object’s grasp affordance; densities are linked to visual stimuli through registration......We present a method for learning object grasp affordance models in 3D from experience, and demonstrate its applicability through extensive testing and evaluation on a realistic and largely autonomous platform. Grasp affordance refers here to relative object-gripper configurations that yield stable...

  16. Human Hand Motion Analysis and Synthesis of Optimal Power Grasps for a Robotic Hand

    Directory of Open Access Journals (Sweden)

    Francesca Cordella

    2014-03-01

    Full Text Available Biologically inspired robotic systems can find important applications in biomedical robotics, since studying and replicating human behaviour can provide new insights into motor recovery, functional substitution and human-robot interaction. The analysis of human hand motion is essential for collecting information about human hand movements useful for generalizing reaching and grasping actions on a robotic system. This paper focuses on the definition and extraction of quantitative indicators for describing optimal hand grasping postures and replicating them on an anthropomorphic robotic hand. A motion analysis has been carried out on six healthy human subjects performing a transverse volar grasp. The extracted indicators point to invariant grasping behaviours between the involved subjects, thus providing some constraints for identifying the optimal grasping configuration. Hence, an optimization algorithm based on the Nelder-Mead simplex method has been developed for determining the optimal grasp configuration of a robotic hand, grounded on the aforementioned constraints. It is characterized by a reduced computational cost. The grasp stability has been tested by introducing a quality index that satisfies the form-closure property. The grasping strategy has been validated by means of simulation tests and experimental trials on an arm-hand robotic system. The obtained results have shown the effectiveness of the extracted indicators to reduce the non-linear optimization problem complexity and lead to the synthesis of a grasping posture able to replicate the human behaviour while ensuring grasp stability. The experimental results have also highlighted the limitations of the adopted robotic platform (mainly due to the mechanical structure to achieve the optimal grasp configuration.

  17. Active Grasp Synthesis for Grasping Unknown Objects

    NARCIS (Netherlands)

    Çall?, B.

    2015-01-01

    Manipulation is a key feature for robots which are designed to work in daily environments like homes, offices and streets. These robots do not often have manipulators that are specialized for specific tasks, but grippers that can grasp the target object. This makes grasping a crucial ability that

  18. Learning Grasp Affordance Densities

    DEFF Research Database (Denmark)

    Detry, Renaud; Kraft, Dirk; Kroemer, Oliver

    2011-01-01

    these and records their outcomes. When a satisfactory number of grasp data is available, an importance-sampling algorithm turns these into a grasp density. We evaluate our method in a largely autonomous learning experiment run on three objects of distinct shapes. The experiment shows how learning increases success......We address the issue of learning and representing object grasp affordance models. We model grasp affordances with continuous probability density functions (grasp densities) which link object-relative grasp poses to their success probability. The underlying function representation is nonparametric...... and relies on kernel density estimation to provide a continuous model. Grasp densities are learned and refined from exploration, by letting a robot “play” with an object in a sequence of graspand-drop actions: The robot uses visual cues to generate a set of grasp hypotheses; it then executes...

  19. Object recognition and grasping using bimanual robot

    OpenAIRE

    Ripoll Ruiz, Aleix

    2016-01-01

    This document presents an algorithm to recognise and locate known bulky objects from a workspace and compute grasps using two anthropomorphic hands. Once valid grasp points have been found and they are kinematically reachable by the manipulator, motion planning and a collision check are performed. In the first place, this document presents a general architecture of the system and the hardware devices and software implemented. Then, a detailed description of the object recognition, grasp and m...

  20. Grasping deficits and adaptations in adults with stereo vision losses.

    Science.gov (United States)

    Melmoth, Dean R; Finlay, Alison L; Morgan, Michael J; Grant, Simon

    2009-08-01

    To examine the effects of permanent versus brief reductions in binocular stereo vision on reaching and grasping (prehension) skills. The first experiment compared prehension proficiency in 20 normal and 20 adults with long-term stereo-deficiency (10 with coarse and 10 with undetectable disparity sensitivities) when using binocular vision or just the dominant or nondominant eye. The second experiment examined effects of temporarily mimicking similar stereoacuity losses in normal adults, by placing defocusing low- or high-plus lenses over one eye, compared with their control (neutral lens) binocular performance. Kinematic and error measures of prehension planning and execution were quantified from movements of the subjects' preferred hand recorded while they reached, precision-grasped, and lifted cylindrical objects (two sizes, four locations) on 40 to 48 trials under each viewing condition. Performance was faster and more accurate with normal compared with reduced binocular vision and least accomplished under monocular conditions. Movement durations were extended (up to approximately 100 ms) whenever normal stereo vision was permanently (ANOVA P stereo-deficiency showed increased variability in digit placement at initial object contact, and they adapted by prolonging (by approximately 25%) the time spent subsequently applying their grasp (ANOVA P stereo vision is essential for skilled precision grasping. Reduced disparity sensitivity results in inaccurate grasp-point selection and greater reliance on nonvisual (somesthetic) information from object contact to control grip stability.

  1. Performance of locomotion and foot grasping following a unilateral thoracic corticospinal tract lesion in monkeys (Macaca mulatta).

    Science.gov (United States)

    Courtine, Grégoire; Roy, Roland R; Raven, Joseph; Hodgson, John; McKay, Heather; Yang, Hong; Zhong, Hui; Tuszynski, Mark H; Edgerton, V Reggie

    2005-10-01

    Six adult monkeys (Macaca mulatta) received a unilateral lesion of the lateral corticospinal tract (CST) in the thoracic spinal cord. Prior to surgery, the animals were trained to perform quadrupedal stepping on a treadmill, and item retrieval with the foot. Whole body kinematics and electromyogram (EMG) recordings were made prior to, and at regular intervals over a period of 12 weeks after the CST lesion. After 1 week of recovery, all monkeys were able to walk unaided quadrupedally on the treadmill. The animals, however, dragged the hindpaw ipsilateral to the lesion along the treadmill belt during the swing phase and showed a significant reorganization of the spatiotemporal pattern of hindlimb (HL) and forelimb (FL) displacements. The inability to appropriately trigger the swing phase resulted in an increase in the cycle duration and stride length of both HLs. The stance duration decreased in the ipsilateral HL, and increased in the contralateral HL and both FLs. Consequently, there was a dramatic disruption of interlimb and intralimb coupling that was reflected in the limb kinematic and EMG patterns. The CST lesion completely abolished the ability of the monkeys to retrieve items with the foot ipsilateral to the lesion and significantly disrupted the level of performance of the contralateral HL during the first 2 weeks post-lesion. Interestingly, selected HL muscles remained almost quiescent when the monkeys attempted to retrieve items, but were unsuccessful with the affected foot at 1 week post-lesion, whereas the capacity to activate the same muscles was preserved, although reduced, during stepping. Spatial and temporal parameters of gait, kinematics, and EMG patterns recorded during locomotion generally converged toward control values over time, but significant differences persisted up to 12 weeks post-lesion. Although some control was recovered over the distal foot musculature, fine foot grasping remained significantly impaired at the end of the testing

  2. Grasping in Robotics

    CERN Document Server

    2013-01-01

    Grasping in Robotics contains original contributions in the field of grasping in robotics with a broad multidisciplinary approach. This gives the possibility of addressing all the major issues related to robotized grasping, including milestones in grasping through the centuries, mechanical design issues, control issues, modelling achievements and issues, formulations and software for simulation purposes, sensors and vision integration, applications in industrial field and non-conventional applications (including service robotics and agriculture).   The contributors to this book are experts in their own diverse and wide ranging fields. This multidisciplinary approach can help make Grasping in Robotics of interest to a very wide audience. In particular, it can be a useful reference book for researchers, students and users in the wide field of grasping in robotics from many different disciplines including mechanical design, hardware design, control design, user interfaces, modelling, simulation, sensors and hum...

  3. GRASP: A multitasking tether

    Directory of Open Access Journals (Sweden)

    Catherine eRabouille

    2016-01-01

    Full Text Available Originally identified as Golgi stacking factors in vitro, the Golgi reassembly stacking protein (GRASP family has been shown to act as membrane tethers with multiple cellular roles. As an update to previous comprehensive reviews of the GRASP family (Vinke et al., 2011 (Giuliani et al., 2011;Jarvela and Linstedt, 2012, we outline here the latest findings concerning their diverse roles. New insights into the mechanics of GRASP-mediated tethering come from recent crystal structures. The models of how GRASP65 and GRASP55 tether membranes relate directly to their role in Golgi ribbon formation in mammalian cells and the unlinking of the ribbon at the onset of mitosis. However, it is also clear that GRASPs act outside the Golgi with roles at the ER and ER exit sites (ERES. Furthermore, the proteins of this family display other roles upon cellular stress, especially in mediating unconventional secretion of both transmembrane proteins (Golgi bypass and cytoplasmic proteins (through secretory autophagosomes.

  4. GRASP: A Multitasking Tether.

    Science.gov (United States)

    Rabouille, Catherine; Linstedt, Adam D

    2016-01-01

    Originally identified as Golgi stacking factors in vitro, the Golgi reassembly stacking protein (GRASP) family has been shown to act as membrane tethers with multiple cellular roles. As an update to previous comprehensive reviews of the GRASP family (Giuliani et al., 2011; Vinke et al., 2011; Jarvela and Linstedt, 2012), we outline here the latest findings concerning their diverse roles. New insights into the mechanics of GRASP-mediated tethering come from recent crystal structures. The models of how GRASP65 and GRASP55 tether membranes relate directly to their role in Golgi ribbon formation in mammalian cells and the unlinking of the ribbon at the onset of mitosis. However, it is also clear that GRASPs act outside the Golgi with roles at the ER and ER exit sites (ERES). Furthermore, the proteins of this family display other roles upon cellular stress, especially in mediating unconventional secretion of both transmembrane proteins (Golgi bypass) and cytoplasmic proteins (through secretory autophagosomes).

  5. GRASP : A Multitasking Tether

    OpenAIRE

    Catherine eRabouille; Adam eLinstedt

    2016-01-01

    Originally identified as Golgi stacking factors in vitro, the Golgi reassembly stacking protein (GRASP) family has been shown to act as membrane tethers with multiple cellular roles. As an update to previous comprehensive reviews of the GRASP family (Giuliani et al., 2011; Vinke et al., 2011; Jarvela and Linstedt, 2012), we outline here the latest findings concerning their diverse roles. New insights into the mechanics of GRASP-mediated tethering come from recent crystal structures. The model...

  6. Grasps Recognition and Evaluation of Stroke Patients for Supporting Rehabilitation Therapy

    Directory of Open Access Journals (Sweden)

    Beatriz Leon

    2014-01-01

    Full Text Available Stroke survivors often suffer impairments on their wrist and hand. Robot-mediated rehabilitation techniques have been proposed as a way to enhance conventional therapy, based on intensive repeated movements. Amongst the set of activities of daily living, grasping is one of the most recurrent. Our aim is to incorporate the detection of grasps in the machine-mediated rehabilitation framework so that they can be incorporated into interactive therapeutic games. In this study, we developed and tested a method based on support vector machines for recognizing various grasp postures wearing a passive exoskeleton for hand and wrist rehabilitation after stroke. The experiment was conducted with ten healthy subjects and eight stroke patients performing the grasping gestures. The method was tested in terms of accuracy and robustness with respect to intersubjects’ variability and differences between different grasps. Our results show reliable recognition while also indicating that the recognition accuracy can be used to assess the patients’ ability to consistently repeat the gestures. Additionally, a grasp quality measure was proposed to measure the capabilities of the stroke patients to perform grasp postures in a similar way than healthy people. These two measures can be potentially used as complementary measures to other upper limb motion tests.

  7. Visual Descriptor Learning for Predicting Grasping Affordances

    DEFF Research Database (Denmark)

    Thomsen, Mikkel Tang

    2016-01-01

    -rates for predicting grasps were between 75% and 90% depending on the object class. The investigations also provided insights into the importance of selecting a proper visual feature space when utilising it for predicting affordances. As a consequence of the gained insights, a semi-local surface feature, the Sliced...... by the task of grasping unknown objects given visual sensor information. The contributions from this thesis stem from three works that all relate to the task of grasping unknown objects but with particular focus on the visual representation part of the problem. First an investigation of a visual feature space...... consisting of surface features was performed. Dimensions in the visual space were varied and the effects were evaluated with the task of grasping unknown object. The evaluation was performed using a novel probabilistic grasp prediction approach based on neighbourhood analysis. The resulting success...

  8. Stereovision and augmented reality for closed-loop control of grasping in hand prostheses.

    Science.gov (United States)

    Markovic, Marko; Dosen, Strahinja; Cipriani, Christian; Popovic, Dejan; Farina, Dario

    2014-08-01

    Technologically advanced assistive devices are nowadays available to restore grasping, but effective and effortless control integrating both feed-forward (commands) and feedback (sensory information) is still missing. The goal of this work was to develop a user friendly interface for the semi-automatic and closed-loop control of grasping and to test its feasibility. We developed a controller based on stereovision to automatically select grasp type and size and augmented reality (AR) to provide artificial proprioceptive feedback. The system was experimentally tested in healthy subjects using a dexterous hand prosthesis to grasp a set of daily objects. The subjects wore AR glasses with an integrated stereo-camera pair, and triggered the system via a simple myoelectric interface. The results demonstrated that the subjects got easily acquainted with the semi-autonomous control. The stereovision grasp decoder successfully estimated the grasp type and size in realistic, cluttered environments. When allowed (forced) to correct the automatic system decisions, the subjects successfully utilized the AR feedback and achieved close to ideal system performance. The new method implements a high level, low effort control of complex functions in addition to the low level closed-loop control. The latter is achieved by providing rich visual feedback, which is integrated into the real life environment. The proposed system is an effective interface applicable with small alterations for many advanced prosthetic and orthotic/therapeutic rehabilitation devices.

  9. Subjective performance evaluations and employee careers

    DEFF Research Database (Denmark)

    Frederiksen, Anders; Lange, Fabian; Kriechell, Ben

    Firms commonly use supervisor evaluations to assess the performance of employees who work in complex environments. Doubts persist whether their subjective nature invalidates using these performance measures to learn about careers of individuals and to inform theory in personnel economics. We...... examine personnel data from six large companies and establish how subjective ratings, interpreted as ordinal rankings of employee performances within narrowly defined peer-groups, correlate with objective career outcomes. We find many similarities across firms in how subjective ratings correlate with base...

  10. Functional classification of grasp strategies used by hemiplegic patients.

    Directory of Open Access Journals (Sweden)

    Alicia García Álvarez

    Full Text Available This study aimed to identify and qualify grasp-types used by patients with stroke and determine the clinical parameters that could explain the use of each grasp. Thirty-eight patients with chronic stroke-related hemiparesis and a range of motor and functional capacities (17 females and 21 males, aged 25-78, and 10 healthy subjects were included. Four objects were used (tissue packet, teaspoon, bottle and tennis ball. Participants were instructed to "grasp the object as if you are going to use it". Three trials were video-recorded for each object. A total of 456 grasps were analysed and rated using a custom-designed Functional Grasp Scale. Eight grasp-types were identified from the analysis: healthy subjects used Multi-pulpar, Pluri-digital, Lateral-pinch and Palmar grasps (Standard Grasps. Patients used the same grasps with in addition Digito-palmar, Raking, Ulnar and Interdigital grasps (Alternative Grasps. Only patients with a moderate or relatively good functional ability used Standard grasps. The correlation and regression analyses showed this was conditioned by sufficient finger and elbow extensor strength (Pluri-digital grasp; thumb extensor and wrist flexor strength (Lateral pinch or in forearm supinator strength (Palmar grasp. By contrast, the patients who had severe impairment used Alternative grasps that did not involve the thumb. These strategies likely compensate specific impairments. Regression and correlation analyses suggested that weakness had a greater influence over grasp strategy than spasticity. This would imply that treatment should focus on improving hand strength and control although reducing spasticity may be useful in some cases.

  11. Rope Caging and Grasping

    NARCIS (Netherlands)

    Kwok, T.H.; Wan, W.; Pan, J.; Wang, C.C.; Yuan, J.; Harada, K; Chen, Y.

    2016-01-01

    We present a novel method for caging grasps in this paper by stretching ropes on the surface of a 3D object. Both topology and shape of a model to be grasped has been
    considered in our approach. Our algorithm can guarantee generating local minimal rings on every topological branches of a given

  12. GRASP : A Multitasking Tether

    NARCIS (Netherlands)

    Rabouille, Catherine; Linstedt, Adam D

    2016-01-01

    Originally identified as Golgi stacking factors in vitro, the Golgi reassembly stacking protein (GRASP) family has been shown to act as membrane tethers with multiple cellular roles. As an update to previous comprehensive reviews of the GRASP family (Giuliani et al., 2011; Vinke et al., 2011;

  13. Control of a neuroprosthesis for grasping using off-line classification of electrocorticographic signals: case study.

    Science.gov (United States)

    Márquez-Chin, C; Popovic, M R; Cameron, T; Lozano, A M; Chen, R

    2009-11-01

    Proof of concept study to control a neuroprosthesis for grasping using identification of arm movements from ECoG signals. To test the feasibility of using electrocorticographic (ECoG) signals as a control method for a neuroprosthesis for grasping. Acute care hospital, Toronto Western Hospital and spinal cord injury (SCI) rehabilitation centre, Toronto Rehabilitation Institute, Lyndhurst Centre. Both hospitals are located in Toronto, Canada. Two subjects participated in this study. The first subject had subdural electrodes implanted on the motor cortex for the treatment of essential tremor (ET). ECoG signals were recorded while the subject performed specific arm movements. The second subject had a complete SCI at C6 level (ASIA B score) and was fitted with a neuroprosthesis, capable of identifying arm movements from ECoG signals off-line, for grasping. To operate the neuroprosthesis, subject 2 issued a command that would trigger the release of a randomly selected ECoG signal recorded from subject 1, associated with a particular arm movement. The neuroprosthesis identified which arm movement was performed at the time of recording and used that information to trigger the stimulation sequence. A correct ECoG classification resulted in the neuroprosthesis producing the correct hand function (that is grasp and release). The neuroprosthesis classified ECoG signals correctly delivering the correct stimulation strategy with 94.5% accuracy. The feasibility of using ECoG signals as a control strategy for a neuroprosthesis for grasping was shown.

  14. Passive reach and grasp with functional electrical stimulation and robotic arm support.

    Science.gov (United States)

    Westerveld, Ard J; Schouten, Alfred C; Veltink, Peter H; van der Kooij, Herman

    2014-01-01

    Rehabilitation of arm and hand function is crucial to increase functional independence of stroke subjects. Here, we investigate the technical feasibility of an integrated training system combining robotics and functional electrical stimulation (FES) to support reach and grasp during functional manipulation of objects. To support grasp and release, FES controlled the thumb and fingers using Model Predictive Control (MPC), while a novel 3D robotic manipulator provided reach support. The system's performance was assessed in both stroke and blindfolded healthy subjects, where the subject's passive arm and hand made functional reach, grasp, move and release movements while manipulating objects. The success rate of complete grasp, move and release tasks with different objects ranged from 33% to 87% in healthy subjects. In severe chronic stroke subjects especially the hand opening had a low success rate (arm and hand for functional pick and place movements. In the current setup, the positioning accuracy of the robot with respect to the object position was critical for the overall performance. The use of a higher virtual stiffness and including feedback of object position in the robot control would likely improve the relative position accuracy. The system has potential for post-stroke rehabilitation, where support could be reduced based on patient performance which is needed to aid motor relearning of reach, grasp and release.

  15. Analysis of Hand and Wrist Postural Synergies in Tolerance Grasping of Various Objects

    Science.gov (United States)

    Liu, Yuan; Jiang, Li; Yang, Dapeng; Liu, Hong

    2016-01-01

    Human can successfully grasp various objects in different acceptable relative positions between human hand and objects. This grasp functionality can be described as the grasp tolerance of human hand, which is a significant functionality of human grasp. To understand the motor control of human hand completely, an analysis of hand and wrist postural synergies in tolerance grasping of various objects is needed. Ten healthy right-handed subjects were asked to perform the tolerance grasping with right hand using 6 objects of different shapes, sizes and relative positions between human hand and objects. Subjects were wearing CyberGlove attaching motion tracker on right hand, allowing a measurement of the hand and wrist postures. Correlation analysis of joints and inter-joint/inter-finger modules were carried on to explore the coordination between joints or modules. As the correlation between hand and wrist module is not obvious in tolerance grasping, individual analysis of wrist synergies would be more practical. In this case, postural synergies of hand and wrist were then presented separately through principal component analysis (PCA), expressed through the principal component (PC) information transmitted ratio, PC elements distribution and reconstructed angle error of joints. Results on correlation comparison of different module movements can be well explained by the influence factors of the joint movement correlation. Moreover, correlation analysis of joints and modules showed the wrist module had the lowest correlation among all inter-finger and inter-joint modules. Hand and wrist postures were both sufficient to be described by a few principal components. In terms of the PC elements distribution of hand postures, compared with previous investigations, there was a greater proportion of movement in the thumb joints especially the interphalangeal (IP) and opposition rotation (ROT) joint. The research could serve to a complete understanding of hand grasp, and the design

  16. Subjective performance evaluations and employee careers

    DEFF Research Database (Denmark)

    Frederiksen, Anders; Lange, Fabian; Kriechel, Ben

    Firms commonly use supervisor ratings to evaluate employees when objective performance measures are unavailable. Supervisor ratings are subjective and data containing supervisor ratings typically stem from individual firm level data sets. For both these reasons, doubts persist on how useful...... such data are for evaluating theories in personnel economics and whether findings from such data generalize to the labor force at large. In this paper, we examine personnel data from six large companies and establish how subjective ratings, interpreted as ordinal rankings of employees within narrowly...

  17. Assessing Grasp Stability Based on Learning and Haptic Data

    DEFF Research Database (Denmark)

    Bekiroglu, Yasemin; Laaksonen, Janne; Jørgensen, Jimmy Alison

    2011-01-01

    An important ability of a robot that interacts with the environment and manipulates objects is to deal with the uncertainty in sensory data. Sensory information is necessary to, for example, perform online assessment of grasp stability. We present methods to assess grasp stability based on haptic...... data and machine-learning methods, including AdaBoost, support vector machines (SVMs), and hidden Markov models (HMMs). In particular, we study the effect of different sensory streams to grasp stability. This includes object information such as shape; grasp information such as approach vector; tactile...... measurements from fingertips; and joint configuration of the hand. Sensory knowledge affects the success of the grasping process both in the planning stage (before a grasp is executed) and during the execution of the grasp (closed-loop online control). In this paper, we study both of these aspects. We propose...

  18. Global cortical activity predicts shape of hand during grasping

    Directory of Open Access Journals (Sweden)

    Harshavardhan Ashok Agashe

    2015-04-01

    Full Text Available Recent studies show that the amplitude of cortical field potentials is modulated in the time domain by grasping kinematics. However, it is unknown if these low frequency modulations persist and contain enough information to decode grasp kinematics in macro-scale activity measured at the scalp via electroencephalography (EEG. Further, it is unclear as to whether joint angle velocities or movement synergies are the optimal kinematics spaces to decode. In this offline decoding study, we infer from human EEG, hand joint angular velocities as well as synergistic trajectories as subjects perform natural reach-to-grasp movements. Decoding accuracy, measured as the correlation coefficient (r between the predicted and actual movement kinematics, was r = 0.49 ± 0.02 across fifteen hand joints. Across the first three kinematic synergies, decoding accuracies were r = 0.59 ± 0.04, 0.47 ± 0.06 and 0.32 ± 0.05. The spatial-temporal pattern of EEG channel recruitment showed early involvement of contralateral frontal-central scalp areas followed by later activation of central electrodes over primary sensorimotor cortical areas. Information content in EEG about the grasp type peaked at 250 ms after movement onset. The high decoding accuracies in this study are significant not only as evidence for time-domain modulation in macro-scale brain activity, but for the field of brain-machine interfaces as well. Our decoding strategy, which harnesses the neural ‘symphony’ as opposed to local members of the neural ensemble (as in intracranial approaches, may provide a means of extracting information about motor intent for grasping without the need for penetrating electrodes and suggests that it may be soon possible to develop non-invasive neural interfaces for the control of prosthetic limbs.

  19. Global cortical activity predicts shape of hand during grasping

    Science.gov (United States)

    Agashe, Harshavardhan A.; Paek, Andrew Y.; Zhang, Yuhang; Contreras-Vidal, José L.

    2015-01-01

    Recent studies show that the amplitude of cortical field potentials is modulated in the time domain by grasping kinematics. However, it is unknown if these low frequency modulations persist and contain enough information to decode grasp kinematics in macro-scale activity measured at the scalp via electroencephalography (EEG). Further, it is unclear as to whether joint angle velocities or movement synergies are the optimal kinematics spaces to decode. In this offline decoding study, we infer from human EEG, hand joint angular velocities as well as synergistic trajectories as subjects perform natural reach-to-grasp movements. Decoding accuracy, measured as the correlation coefficient (r) between the predicted and actual movement kinematics, was r = 0.49 ± 0.02 across 15 hand joints. Across the first three kinematic synergies, decoding accuracies were r = 0.59 ± 0.04, 0.47 ± 0.06, and 0.32 ± 0.05. The spatial-temporal pattern of EEG channel recruitment showed early involvement of contralateral frontal-central scalp areas followed by later activation of central electrodes over primary sensorimotor cortical areas. Information content in EEG about the grasp type peaked at 250 ms after movement onset. The high decoding accuracies in this study are significant not only as evidence for time-domain modulation in macro-scale brain activity, but for the field of brain-machine interfaces as well. Our decoding strategy, which harnesses the neural “symphony” as opposed to local members of the neural ensemble (as in intracranial approaches), may provide a means of extracting information about motor intent for grasping without the need for penetrating electrodes and suggests that it may be soon possible to develop non-invasive neural interfaces for the control of prosthetic limbs. PMID:25914616

  20. Subject to Form: Research Interviews, Performative Subjectivity, Professional Development

    Science.gov (United States)

    Sarigianides, Sophia Tatiana

    2010-01-01

    In this dissertation, I analyze teacher, literacy coach and researcher subjectivities in a five-year study of on-site professional development with middle-grade Language Arts teachers in a school designated by its district and state as severely underperforming. Interested in the role of research interviews as both research method and cultural…

  1. Grasp posture alters visual processing biases near the hands

    Science.gov (United States)

    Thomas, Laura E.

    2015-01-01

    Observers experience biases in visual processing for objects within easy reach of their hands that may assist them in evaluating items that are candidates for action. I investigated the hypothesis that hand postures affording different types of actions differentially bias vision. Across three experiments, participants performed global motion detection and global form perception tasks while their hands were positioned a) near the display in a posture affording a power grasp, b) near the display in a posture affording a precision grasp, or c) in their laps. Although the power grasp posture facilitated performance on the motion task, the precision grasp posture instead facilitated performance on the form task. These results suggest that the visual system weights processing based on an observer’s current affordances for specific actions: fast and forceful power grasps enhance temporal sensitivity, while detail-oriented precision grasps enhance spatial sensitivity. PMID:25862545

  2. Weber's law in 2D and 3D grasping.

    Science.gov (United States)

    Ozana, Aviad; Ganel, Tzvi

    2017-09-04

    Visually guided grasping movements directed to real, 3D objects are characterized by a distinguishable trajectory pattern that evades the influence of Weber's law, a basic principle of perception. Conversely, grasping trajectories directed to 2D line drawings of objects adhere to Weber's law. It can be argued, therefore, that during 2D grasping, the visuomotor system fails at operating in analytic mode and is intruded by irrelevant perceptual information. Here, we explored the visual and tactile cues that enable such analytic processing during grasping. In Experiment 1, we compared grasping directed to 3D objects with grasping directed to 2D object photos. Grasping directed to photos adhered to Weber's law, suggesting that richness in visual detail does not contribute to analytic processing. In Experiment 2, we tested whether the visual presentation of 3D objects could support analytic processing even when only partial object-specific tactile information is provided. Surprisingly, grasping could be performed in an analytic fashion, violating Weber's law. In Experiment 3, participants were denied of any haptic feedback at the end of the movement and grasping trajectories again showed adherence to Weber's law. Taken together, the findings suggest that the presentation of real objects combined with indirect haptic information at the end of the movement is sufficient to allow analytic processing during grasp.

  3. Fast C-shape grasping for unknown objects

    NARCIS (Netherlands)

    Lei, Q.; Meijer, Jonathan; Wisse, M.; Buss, Martin; Sawodny, Oliver

    2017-01-01

    This paper identifies high-performing Open Motion Planning Library (OMPL) planners for grasp execution and simultaneously presents useful benchmark data. Four grasp executions were defined using a UR5 manipulator. The performance was measured by means of solved runs, computing time and path

  4. Electrotactile EMG feedback improves the control of prosthesis grasping force

    Science.gov (United States)

    Schweisfurth, Meike A.; Markovic, Marko; Dosen, Strahinja; Teich, Florian; Graimann, Bernhard; Farina, Dario

    2016-10-01

    Objective. A drawback of active prostheses is that they detach the subject from the produced forces, thereby preventing direct mechanical feedback. This can be compensated by providing somatosensory feedback to the user through mechanical or electrical stimulation, which in turn may improve the utility, sense of embodiment, and thereby increase the acceptance rate. Approach. In this study, we compared a novel approach to closing the loop, namely EMG feedback (emgFB), to classic force feedback (forceFB), using electrotactile interface in a realistic task setup. Eleven intact-bodied subjects and one transradial amputee performed a routine grasping task while receiving emgFB or forceFB. The two feedback types were delivered through the same electrotactile interface, using a mixed spatial/frequency coding to transmit 8 discrete levels of the feedback variable. In emgFB, the stimulation transmitted the amplitude of the processed myoelectric signal generated by the subject (prosthesis input), and in forceFB the generated grasping force (prosthesis output). The task comprised 150 trials of routine grasping at six forces, randomly presented in blocks of five trials (same force). Interquartile range and changes in the absolute error (AE) distribution (magnitude and dispersion) with respect to the target level were used to assess precision and overall performance, respectively. Main results. Relative to forceFB, emgFB significantly improved the precision of myoelectric commands (min/max of the significant levels) for 23%/36% as well as the precision of force control for 12%/32%, in intact-bodied subjects. Also, the magnitude and dispersion of the AE distribution were reduced. The results were similar in the amputee, showing considerable improvements. Significance. Using emgFB, the subjects therefore decreased the uncertainty of the forward pathway. Since there is a correspondence between the EMG and force, where the former anticipates the latter, the emgFB allowed for

  5. Hand-use and tool-use in grasping control.

    Science.gov (United States)

    Itaguchi, Yoshihiro; Fukuzawa, Kazuyoshi

    2014-11-01

    The goal of this study was to elucidate the underlying mechanisms of hand and tool grasping control. We assumed that there is a single principle-governing grasping control irrespective of its effectors and that the degree of prior experience of the effector determines the smoothness of aperture control. Eight participants performed a reach-to-grasp task with four different effectors: index finger and thumb, middle finger and thumb, chopsticks, and a scissor-like tool. Although we employed different effectors with large mechanical variations and different degrees of prior use, maximum grip aperture was scaled as a function of object size and appeared at almost the same timing in all four types of grasping movements. Moreover, reaching time did not substantially differ among grasping conditions. However, plateau duration of the aperture profile differed by effector. Plateau duration was the longest in the unfamiliar scissor-like tool grasping condition. There was no difference between the unfamiliar hand-use grasp with the thumb and the middle finger and the familiar tool-grasp with chopsticks. The familiar hand-use grasp with the thumb and the index finger had the shortest plateau duration. These results supported the idea that there is an effector-independent continuity between hand-use and tool-use in motor control as a function of prior degree of use, rather than the conventionally assumed dichotomy between them.

  6. Safe Robotic Grasping: Minimum Impact-Force Grasp Selection

    OpenAIRE

    Mavrakis, Nikos; E, Amir M Ghalamzan; Stolkin, Rustam

    2017-01-01

    This paper addresses the problem of selecting from a choice of possible grasps, so that impact forces will be minimised if a collision occurs while the robot is moving the grasped object along a post-grasp trajectory. Such considerations are important for safety in human-robot interaction, where even a certified "human-safe" (e.g. compliant) arm may become hazardous once it grasps and begins moving an object, which may have significant mass, sharp edges or other dangers. Additionally, minimis...

  7. Hand Grasping Synergies As Biometrics

    Directory of Open Access Journals (Sweden)

    Ramana Vinjamuri

    2017-05-01

    Full Text Available Recently, the need for more secure identity verification systems has driven researchers to explore other sources of biometrics. This includes iris patterns, palm print, hand geometry, facial recognition, and movement patterns (hand motion, gait, and eye movements. Identity verification systems may benefit from the complexity of human movement that integrates multiple levels of control (neural, muscular, and kinematic. Using principal component analysis, we extracted spatiotemporal hand synergies (movement synergies from an object grasping dataset to explore their use as a potential biometric. These movement synergies are in the form of joint angular velocity profiles of 10 joints. We explored the effect of joint type, digit, number of objects, and grasp type. In its best configuration, movement synergies achieved an equal error rate of 8.19%. While movement synergies can be integrated into an identity verification system with motion capture ability, we also explored a camera-ready version of hand synergies—postural synergies. In this proof of concept system, postural synergies performed well, but only when specific postures were chosen. Based on these results, hand synergies show promise as a potential biometric that can be combined with other hand-based biometrics for improved security.

  8. From robot to human grasping simulation

    CERN Document Server

    León, Beatriz; Sancho-Bru, Joaquin

    2013-01-01

    The human hand and its dexterity in grasping and manipulating objects are some of the hallmarks of the human species. For years, anatomic and biomechanical studies have deepened the understanding of the human hand’s functioning and, in parallel, the robotics community has been working on the design of robotic hands capable of manipulating objects with a performance similar to that of the human hand. However, although many researchers have partially studied various aspects, to date there has been no comprehensive characterization of the human hand’s function for grasping and manipulation of

  9. The Role of Object Contact in Pointing and Grasping

    NARCIS (Netherlands)

    M. Biegstraten-Meeuws

    2005-01-01

    textabstractWe grasp and lift objects many times a day. Most of us perform such a task without any difficulty. However even just grasping the packet of chocolate flakes at the breakfast table is in fact a complex task. Our brain has to – among others - coordinate and select multiple muscles, select

  10. Golgi GRASPs: moonlighting membrane tethers

    Directory of Open Access Journals (Sweden)

    Jarvela T

    2012-05-01

    Full Text Available Timothy Jarvela, Adam D LinstedtDepartment of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USAAbstract: The identification of mammalian Golgi reassembly stacking proteins (GRASPs 15 years ago was followed by experiments implicating them in diverse functions, including two differing structural roles in Golgi biogenesis and at least two distinct roles in the secretion of proteins. GRASP55 and GRASP65 are localized to cis and medial/trans Golgi cisternae, respectively. They are both required for stacking of Golgi membranes in a Golgi reassembly assay. Depletion of either GRASP from cultured cells prevents the linking of Golgi membranes into their normal ribbon-like network. While GRASPs are not required for transport of secretory cargo per se, they are required for ER-to-Golgi transport of certain specific cargo, such as those containing a C-terminal valine motif. Surprisingly, GRASPs also promote secretion of cargo by the so-called unconventional secretory pathway, which bypasses the Golgi apparatus where the GRASPs reside. Furthermore, regulation of GRASP activity is now recognized for its connections to cell cycle control, development, and disease. Underlying these diverse activities is the structurally conserved N-terminal GRASP domain whose crystal structure was recently determined. It consists of a tandem array of atypical PSD95–DlgA–Zo–1 (PDZ domains, which are well-known protein–protein interaction motifs. The GRASP PDZ domains are used to localize the proteins to the Golgi as well as GRASP-mediated membrane tethering and cargo interactions. These activities are regulated, in part, by phosphorylation of the large unstructured C-terminal domain.Keywords: GRASP, review, membrane, tether, PDZ domain, secretory chaperone, unconventional secretion

  11. The Validity of Subjective Performance Measures

    DEFF Research Database (Denmark)

    Meier, Kenneth J.; Winter, Søren C.; O'Toole, Laurence J.

    2015-01-01

    Public management studies are increasingly using survey data on managers’ perceptions of performance to measure organizational performance. The perceptual measures are tempting to apply because archival performance data or surveys of target group outcomes and satisfaction are often lacking, costly...... to provide, and are highly policy specific rendering generalization difficult. But are perceptual performance measures valid, and do they generate unbiased findings? We examine these questions in a comparative study of middle managers in schools in Texas and Denmark. The findings are remarkably similar...... the resources it has. Even worse, the use of perceptual performance measures seems to provide biased estimates when examining how management affects performance....

  12. Grasp Densities for Grasp Refinement in Industrial Bin Picking

    DEFF Research Database (Denmark)

    Hupfauf, Benedikt; Hahn, Heiko; Bodenhagen, Leon

    Automatic picking of randomly distributed objects from a bin has been denoted the "Holy Grail" in the world of robot automation. A particular property of the bin-picking scenario (in contrast to most other industrial robot applications) is that grasp errors are allowed to occur: Usually bin......-pickers fill feeding stations such that occasional errors do not disturb the main process, since the feeding station has a buffer of a number of objects which it provides to the assembly process. Grasping errors are usually detected by haptic feedback. We intend to utilize the huge amount of grasp data...... in terms of object-relative gripper pose, can be learned from empirical experience, and allow the automatic choice of optimal grasps in a given scene context (object pose, workspace constraints, etc.). We will show grasp densities extracted from empirical data in a real industrial bin picking context...

  13. All-day performance variations in normal and narcoleptic subjects.

    Science.gov (United States)

    Godbout, R; Montplaisir, J

    1986-01-01

    This study compared the performance of narcoleptic and control subjects on one psychomotor task, examined the recuperative power of naps in narcoleptic subjects, and evaluated the respective recuperative values of REM and NREM sleep. Ten untreated narcoleptic and eight control subjects repeatedly responded to a choice reaction time task during days with and days without napping. Narcoleptic subjects exhibited low performance levels relative to control subjects on all variables. Napping improved the performance of narcoleptic subjects except for the number of long latency (reaction time greater than 1,000 ms) responses. Finally, performance, particularly on accuracy measures, was better, although not significantly, after NREM naps when compared with REM naps.

  14. Does postural stability affect grasping?

    NARCIS (Netherlands)

    Voudouris, D.; Radhakrishnan, S.; Hatzitaki, V.; Brenner, E.

    2013-01-01

    We examined whether challenging upright stance influences the execution of a grasping task. Participants reached to grasp a small sphere while standing either on a stable surface or on foam. Before reaching for the sphere, participants exhibited more body sway and greater fluctuations in the centre

  15. Minimal Reducts with Grasp

    Directory of Open Access Journals (Sweden)

    Iris Iddaly Mendez Gurrola

    2011-03-01

    Full Text Available The proper detection of patient level of dementia is important to offer the suitable treatment. The diagnosis is based on certain criteria, reflected in the clinical examinations. From these examinations emerge the limitations and the degree in which each patient is in. In order to reduce the total of limitations to be evaluated, we used the rough set theory, this theory has been applied in areas of the artificial intelligence such as decision analysis, expert systems, knowledge discovery, classification with multiple attributes. In our case this theory is applied to find the minimal limitations set or reduct that generate the same classification that considering all the limitations, to fulfill this purpose we development an algorithm GRASP (Greedy Randomized Adaptive Search Procedure.

  16. Automatic Grasp Generation and Improvement for Industrial Bin-Picking

    DEFF Research Database (Denmark)

    Kraft, Dirk; Ellekilde, Lars-Peter; Rytz, Jimmy Alison

    2014-01-01

    This paper presents work on automatic grasp generation and grasp learning for reducing the manual setup time and increase grasp success rates within bin-picking applications. We propose an approach that is able to generate good grasps automatically using a dynamic grasp simulator, a newly developed...... and achieve comparable results and that our learning approach can improve system performance significantly. Automatic bin-picking is an important industrial process that can lead to significant savings and potentially keep production in countries with high labour cost rather than outsourcing it. The presented...... work allows to minimize cycle time as well as setup cost, which are essential factors in automatic bin-picking. It therefore leads to a wider applicability of bin-picking in industry....

  17. Development of a non-invasive, multifunctional grasp neuroprosthesis and its evaluation in an individual with a high spinal cord injury.

    Science.gov (United States)

    Rupp, Rüdiger; Kreilinger, Alex; Rohm, Martin; Kaiser, Vera; Müller-Putz, Gernot R

    2012-01-01

    Over the last decade the improvement of a missing hand function by application of neuroprostheses in particular the implantable Freehand system has been successfully shown in high spinal cord injured individuals. The clinically proven advantages of the Freehand system is its ease of use, the reproducible generation of two distinct functional grasp patterns and an analog control scheme based on movements of the contralateral shoulder. However, after the Freehand system is not commercially available for more than ten years, alternative grasp neuroprosthesis with a comparable functionality are still missing. Therefore, the aim of this study was to develop a non-invasive neuroprosthesis and to show that a degree of functional restoration can be provided to end users comparable to implanted devices. By introduction of an easy to handle forearm electrode sleeve the reproducible generation of two grasp patterns has been achieved. Generated grasp forces of the palmar grasp are in the range of the implanted system. Though pinch force of the lateral grasp is significantly lower, it can effectively used by a tetraplegic subject to perform functional tasks. The non-invasive grasp neuroprosthesis developed in this work may serve as an easy to apply and inexpensive way to restore a missing hand and finger function at any time after spinal cord injury.

  18. Subjective performance evaluation and gender discrimination

    NARCIS (Netherlands)

    Maas, V.S.; Torres-Gonzalez, R.

    2011-01-01

    Gender discrimination continues to be a problem in organizations. It is therefore important that organizations use performance evaluation methods that ensure equal opportunities for men and women. This article reports the results of an experiment to investigate whether and, if so, how the gender of

  19. Occupational performance of women subjected to mastectomy

    Directory of Open Access Journals (Sweden)

    Jamylle Silva de Brito

    2014-12-01

    Full Text Available Among the several therapeutic approaches to combat breast cancer, mastectomy is the most feared by women, not only because of its aggressive invasive characteristics to the female body, but also because of its biological, functional, emotional, and social repercussions. The objective of the present study was to outline the occupational performance profile through the description of daily life, productive and leisure activities of women that have undergone mastectomy. This is a descriptive cross-sectional study with 21 women carried out at a school hospital in Recife, Pernambuco state, Brazil, from June to September, 2011. We used a sociodemographic questionnaire and occupational assessment by the Canadian Model of Occupational Performance (CMOP. In the occupational performance evaluation, Productivity was the most compromised area, followed by Leisure. Taking care of the body after mastectomy was not a restraint to the development of the daily-life, productive and leisure activities for the operated women, although some reorganization was needed to maintain a satisfactory performance.

  20. Electromyographic analysis of goal-directed grasping behavior in the American lobster.

    Science.gov (United States)

    Tomina, Yusuke; Takahata, Masakazu

    2014-10-15

    Animals spontaneously initiate goal-directed behavior including foraging action based on their appetitive motivation. The American lobster Homarus americanus exhibits grasping behavior with its crusher claw as feeding behavior that can be initiated after appropriate operant conditioning. In order to quantitatively characterize the goal-directed grasping behavior with a time resolution fine enough for neurophysiological analysis of its initiation and control mechanisms, we made simultaneous electromyographic (EMG) recording from grasping- and reaching-related muscles of the crusher claw while animals initiated grasping behavior. We developed an in vivo extracellular recording chamber that allowed the animal under a semi-restrained condition to perform operant reward learning of claw grasping. Three muscles in the crusher claw (propodite-dactyl closer/opener and coxal protractor) were found to be closely associated with spontaneous grasping behavior. In spontaneous grasping, the activation of those muscles consistently preceded the grasping onset time and exhibited different activity patterns from the grasp induced by a mechanical stimulus. Furthermore, we found that the timing of coxal protractor activation was closer to the grasp onset and its activity was briefer for goal-directed grasping behavior in trained and hungry animals than for non-goal-directed spontaneous grasping behavior in naive or satiated animals. It is suggested that the goal-directed grasping behavior of lobster is characterized, at least partly, by experience-dependent briefer activity of specific muscles involved in reaching action. © 2014. Published by The Company of Biologists Ltd.

  1. Occupational performance of women subjected to mastectomy

    OpenAIRE

    Jamylle Silva de Brito; Juliana Fonsêca de Queiroz Marcelino

    2014-01-01

    Among the several therapeutic approaches to combat breast cancer, mastectomy is the most feared by women, not only because of its aggressive invasive characteristics to the female body, but also because of its biological, functional, emotional, and social repercussions. The objective of the present study was to outline the occupational performance profile through the description of daily life, productive and leisure activities of women that have undergone mastectomy. This is a descriptive ...

  2. Passive Aerial Grasping of Ferrous Objects

    KAUST Repository

    Fiaz, Usman Amin

    2017-10-19

    Aerial transportation is probably the most efficient way to supply quick and effective aid especially in cases of emergency like search and rescue operations. Thus the ability to grasp and deliver objects is of vital importance in all sorts of unmanned and autonomous aerial operations. We detail a simple yet novel approach for aerial grasping of ferrous objects using a passive magnetic pickup and an impulse based drop mechanism. The design enables our gripper to grasp ferrous objects using single as well as multiple gripping pads, with visual as well as pickup and drop feedback. We describe the various components of the gripper with emphasis on its low mass and high lift capability since weight is a matter of high consideration in all aerial applications. In addition, we investigate and address the issues that may cause our design to fail. We demonstrate by experiments that the proposed design is robust and effective, based on its high payload capability, its sturdiness against possible slide during aggressive aerial maneuvers, and optimum performance of the drop mechanism for the designed range of payloads. We also show that the gripper is able to pick up and drop a single as well as multiple ferrous objects of different shapes, curvature, and inclination, which also involves picking up an object and then grasping the next, while keeping hold of the previous one.

  3. Using an accelerometer for analyzing a reach-to-grasp movement after stroke

    Directory of Open Access Journals (Sweden)

    Stella Maris Michaelsen

    2013-12-01

    Full Text Available The purpose of this study was using an accelerometer to access the kinematics of reach-to-grasp movements in subjects with hemiparesis. Eight subjects (59.4 ± 6.9 years old with chronic hemiparesis (50.9 ± 25.8 months post-stroke participated in this study. Kinematic assessment was performed using a triaxial accelerometer (EMG Systems, Brazil attached to the subjects' forearm. Ten reach-to-grasp movements of grabbing a 500ml-size bottle were performed by the subjects with the paretic and the non-paretic upper limbs (ULs. The following space-temporal variables were calculated and used to compare the paretic and non-paretic ULs: movement time (MT, time to reach the peak velocity, absolute and relative (TPV and TPV%MT, relative deceleration duration (DEC%MT, time to peak acceleration (TPA and peak hand acceleration (PA. Movements were slower in the paretic UL with increased MT, TPA and DEC. The accelerometer allowed to identify of changes in reaching-to-grasp movements of subjects with hemiparesis. When complex systems are not available, accelerometers can be an alternative to measure UL movements.

  4. Performance pinned down: studying subjectivity and the language of performance

    NARCIS (Netherlands)

    Hoedemaekers, C.; Keegan, A.

    2010-01-01

    We draw on Lacan’s notion of language to study employee subjectivity in a public sector organization (Publica) in the Netherlands. Our main contribution lies in using Lacan’s theorization of language and subjectivity as a basis for a detailed textual analysis of how local organizational discourses

  5. Grasping Pattern Recognition and Grasping Force Estimation For Prosthetic Hands

    OpenAIRE

    Zhang Bing-Ke; Zhong Guo-Liang; Deng Hua

    2016-01-01

    Human’s movement can be decoded by surface electromyography (EMG), and the prosthetic hand can be controlled freely through EMG signal. This paper proposes a grasping pattern and force synchronized decoding method for prosthetic hands. Considering pattern recognition and force estimation simultaneously, this paper analyzes whether different muscle contraction levels affect pattern recognition and whether different grasping modes have impact on force estimation, then proposes two schemes to co...

  6. Subjectivity

    Directory of Open Access Journals (Sweden)

    Jesús Vega Encabo

    2015-11-01

    Full Text Available In this paper, I claim that subjectivity is a way of being that is constituted through a set of practices in which the self is subject to the dangers of fictionalizing and plotting her life and self-image. I examine some ways of becoming subject through narratives and through theatrical performance before others. Through these practices, a real and active subjectivity is revealed, capable of self-knowledge and self-transformation. 

  7. Prosthetic hand sensor placement: Analysis of touch perception during the grasp

    Directory of Open Access Journals (Sweden)

    Mirković Bojana

    2014-01-01

    Full Text Available Humans rely on their hands to perform everyday tasks. The hand is used as a tool, but also as the interface to “sense” the world. Current prosthetic hands are based on sophisticated multi-fingered structures, and include many sensors which counterpart natural proprioceptors and exteroceptors. The sensory information is used for control, but not sent to the user of the hand (amputee. Grasping without sensing is not good enough. This research is part of the development of the sensing interface for amputees, specifically addressing the analysis of human perception while grasping. The goal is to determine the small number of preferred positions of sensors on the prosthetic hand. This task has previously been approached by trying to replicate a natural sensory system characteristic for healthy humans, resulting in a multitude of redundant sensors and basic inability to make the patient aware of the sensor readings on the subconscious level. We based our artificial perception system on the reported sensations of humans when grasping various objects without seeing the objects (obstructed visual feedback. Subjects, with no known sensory deficits, were asked to report on the touch sensation while grasping. The analysis included objects of various sizes, weights, textures and temperatures. Based on this data we formed a map of the preferred positions for the sensors that is appropriate for five finger human-like robotic hand. The final map was intentionally minimized in size (number of sensors.

  8. Efficient GRASP based heuristics for the capacitated continuous location-allocation problem

    Science.gov (United States)

    Luis, Martino; Ramli, Mohammad Fadzli; Saputra, Ruswiati Surya

    2015-05-01

    This paper explores the np-hard capacitated continuous location-allocation problem, where the number of facilities to be located is specified and each of which has a constant capacity. Efficient greedy randomised adaptive search procedure (GRASP) based heuristics are proposed to tackle the problem. A scheme that applies the furthest distance rule (FDR) and self-adjusted threshold parameters to generate initial facility locations that are situated sparsely within GRASP framework is also put forward. The construction of the restricted candidate list (RCL) within GRASP is also guided by applying a concept of restricted regions that prevents new facility locations to be sited too close to the previous selected facility locations. The performance of the proposed GRASP heuristics is evaluated by conducting experiments using data sets taken from the literature typically used for the uncapacitated continuous location-allocation problem. The preliminary computational experiments show that the proposed methods provide encouraging solutions when compared to recently published papers. Some future research avenues on the subject are also briefly highlighted.

  9. Robot Grasp Learning by Demonstration without Predefined Rules

    Directory of Open Access Journals (Sweden)

    César Fernández

    2011-12-01

    Full Text Available A learning‐based approach to autonomous robot grasping is presented. Pattern recognition techniques are used to measure the similarity between a set of previously stored example grasps and all the possible candidate grasps for a new object. Two sets of features are defined in order to characterize grasps: point attributes describe the surroundings of a contact point; point‐set attributes describe the relationship between the set of n contact points (assuming an n‐fingered robot gripper is used. In the experiments performed, the nearest neighbour classifier outperforms other approaches like multilayer perceptrons, radial basis functions or decision trees, in terms of classification accuracy, while computational load is not excessive for a real time application (a grasp is fully synthesized in 0.2 seconds. The results obtained on a synthetic database show that the proposed system is able to imitate the grasping behaviour of the user (e.g. the system learns to grasp a mug by its handle. All the code has been made available for testing purposes.

  10. Robot Grasp Learning by Demonstration without Predefined Rules

    Directory of Open Access Journals (Sweden)

    César Fernández

    2011-12-01

    Full Text Available A learning-based approach to autonomous robot grasping is presented. Pattern recognition techniques are used to measure the similarity between a set of previously stored example grasps and all the possible candidate grasps for a new object. Two sets of features are defined in order to characterize grasps: point attributes describe the surroundings of a contact point; point-set attributes describe the relationship between the set of n contact points (assuming an n-fingered robot gripper is used. In the experiments performed, the nearest neighbour classifier outperforms other approaches like multilayer perceptrons, radial basis functions or decision trees, in terms of classification accuracy, while computational load is not excessive for a real time application (a grasp is fully synthesized in 0.2 seconds. The results obtained on a synthetic database show that the proposed system is able to imitate the grasping behaviour of the user (e.g. the system learns to grasp a mug by its handle. All the code has been made available for testing purposes.

  11. Exploring manual asymmetries during grasping: a dynamic causal modeling approach.

    Directory of Open Access Journals (Sweden)

    Chiara eBegliomini

    2015-02-01

    Full Text Available Recording of neural activity during grasping actions in macaques showed that grasp-related sensorimotor transformations are accomplished in a circuit constituted by the anterior part of the intraparietal sulcus (AIP, the ventral (F5 and the dorsal (F2 region of the premotor area. In humans, neuroimaging studies have revealed the existence of a similar circuit, involving the putative homolog of macaque areas AIP, F5 and F2. These studies have mainly considered grasping movements performed with the right dominant hand and only a few studies have measured brain activity associated with a movement performed with the left non-dominant hand. As a consequence of this gap, how the brain controls for grasping movement performed with the dominant and the non-dominant hand still represents an open question. A functional resonance imaging experiment (fMRI has been conducted, and effective connectivity (Dynamic Causal Modelling, DCM was used to assess how connectivity among grasping-related areas is modulated by hand (i.e., left and right during the execution of grasping movements towards a small object requiring precision grasping. Results underlined boosted inter-hemispheric couplings between dorsal premotor cortices during the execution of movements performed with the left rather than the right dominant hand. More specifically, they suggest that the dorsal premotor cortices may play a fundamental role in monitoring the configuration of fingers when grasping movements are performed by either the right and the left hand. This role becomes particularly evident when the hand less-skilled (i.e., the left hand to perform such action is utilized. The results are discussed in light of recent theories put forward to explain how parieto-frontal connectivity is modulated by the execution of prehensile movements.

  12. Decoding natural reach-and-grasp actions from human EEG

    Science.gov (United States)

    Schwarz, Andreas; Ofner, Patrick; Pereira, Joana; Ioana Sburlea, Andreea; Müller-Putz, Gernot R.

    2018-02-01

    Objective. Despite the high number of degrees of freedom of the human hand, most actions of daily life can be executed incorporating only palmar, pincer and lateral grasp. In this study we attempt to discriminate these three different executed reach-and-grasp actions utilizing their EEG neural correlates. Approach. In a cue-guided experiment, 15 healthy individuals were asked to perform these actions using daily life objects. We recorded 72 trials for each reach-and-grasp condition and from a no-movement condition. Main results. Using low-frequency time domain features from 0.3 to 3 Hz, we achieved binary classification accuracies of 72.4%, STD  ±  5.8% between grasp types, for grasps versus no-movement condition peak performances of 93.5%, STD  ±  4.6% could be reached. In an offline multiclass classification scenario which incorporated not only all reach-and-grasp actions but also the no-movement condition, the highest performance could be reached using a window of 1000 ms for feature extraction. Classification performance peaked at 65.9%, STD  ±  8.1%. Underlying neural correlates of the reach-and-grasp actions, investigated over the primary motor cortex, showed significant differences starting from approximately 800 ms to 1200 ms after the movement onset which is also the same time frame where classification performance reached its maximum. Significance. We could show that it is possible to discriminate three executed reach-and-grasp actions prominent in people’s everyday use from non-invasive EEG. Underlying neural correlates showed significant differences between all tested conditions. These findings will eventually contribute to our attempt of controlling a neuroprosthesis in a natural and intuitive way, which could ultimately benefit motor impaired end users in their daily life actions.

  13. Expertise affects representation structure and categorical activation of grasp postures in climbing

    Directory of Open Access Journals (Sweden)

    Bettina E. Bläsing

    2014-09-01

    Full Text Available In indoor rock climbing, the perception of object properties and the adequate execution of grasping actions highly determine climbers’ performance. In two consecutive experiments, effects of climbing expertise on the cognitive activation of grasping actions following the presentation of climbing holds was investigated. Experiment 1 evaluated the representation of climbing holds in the long-term memory of climbers and non-climbers with the help of a psychometric measurement method. Within a hierarchical splitting procedure subjects had to decide about the similarity of required grasping postures. For the group of climbers, representation structures corresponded clearly to four grip types. In the group of non-climbers, representation structures differed more strongly than in climbers and did not clearly refer to grip types. To learn about categorical knowledge activation in Experiment 2, a priming paradigm was applied. Images of hands in grasping postures were presented as targets and images of congruent, neutral, or incongruent climbing holds were used as primes. Only in climbers, reaction times were shorter and error rates were smaller for the congruent condition than for the incongruent condition. The neutral condition resulted in intermediate performance. The findings suggest that perception of climbing holds activates the commonly associated grasping postures in climbers but not in non-climbers. The findings of this study give evidence that the categorization of visually perceived objects is fundamentally influenced by the cognitive-motor potential for interaction, which depends on the observer’s experience and expertise. Thus, motor expertise not only facilitates precise action perception, but also benefits the perception of action-relevant objects.

  14. Expertise affects representation structure and categorical activation of grasp postures in climbing.

    Science.gov (United States)

    Bläsing, Bettina E; Güldenpenning, Iris; Koester, Dirk; Schack, Thomas

    2014-01-01

    In indoor rock climbing, the perception of object properties and the adequate execution of grasping actions highly determine climbers' performance. In two consecutive experiments, effects of climbing expertise on the cognitive activation of grasping actions following the presentation of climbing holds was investigated. Experiment 1 evaluated the representation of climbing holds in the long-term memory of climbers and non-climbers with the help of a psychometric measurement method. Within a hierarchical splitting procedure subjects had to decide about the similarity of required grasping postures. For the group of climbers, representation structures corresponded clearly to four grip types. In the group of non-climbers, representation structures differed more strongly than in climbers and did not clearly refer to grip types. To learn about categorical knowledge activation in Experiment 2, a priming paradigm was applied. Images of hands in grasping postures were presented as targets and images of congruent, neutral, or incongruent climbing holds were used as primes. Only in climbers, reaction times were shorter and error rates were smaller for the congruent condition than for the incongruent condition. The neutral condition resulted in intermediate performance. The findings suggest that perception of climbing holds activates the commonly associated grasping postures in climbers but not in non-climbers. The findings of this study give evidence that the categorization of visually perceived objects is fundamentally influenced by the cognitive-motor potential for interaction, which depends on the observer's experience and expertise. Thus, motor expertise not only facilitates precise action perception, but also benefits the perception of action-relevant objects.

  15. Expertise affects representation structure and categorical activation of grasp postures in climbing

    Science.gov (United States)

    Bläsing, Bettina E.; Güldenpenning, Iris; Koester, Dirk; Schack, Thomas

    2014-01-01

    In indoor rock climbing, the perception of object properties and the adequate execution of grasping actions highly determine climbers' performance. In two consecutive experiments, effects of climbing expertise on the cognitive activation of grasping actions following the presentation of climbing holds was investigated. Experiment 1 evaluated the representation of climbing holds in the long-term memory of climbers and non-climbers with the help of a psychometric measurement method. Within a hierarchical splitting procedure subjects had to decide about the similarity of required grasping postures. For the group of climbers, representation structures corresponded clearly to four grip types. In the group of non-climbers, representation structures differed more strongly than in climbers and did not clearly refer to grip types. To learn about categorical knowledge activation in Experiment 2, a priming paradigm was applied. Images of hands in grasping postures were presented as targets and images of congruent, neutral, or incongruent climbing holds were used as primes. Only in climbers, reaction times were shorter and error rates were smaller for the congruent condition than for the incongruent condition. The neutral condition resulted in intermediate performance. The findings suggest that perception of climbing holds activates the commonly associated grasping postures in climbers but not in non-climbers. The findings of this study give evidence that the categorization of visually perceived objects is fundamentally influenced by the cognitive-motor potential for interaction, which depends on the observer's experience and expertise. Thus, motor expertise not only facilitates precise action perception, but also benefits the perception of action-relevant objects. PMID:25309480

  16. Differences between kinematic synergies and muscle synergies during two-digit grasping

    Directory of Open Access Journals (Sweden)

    Michele eTagliabue

    2015-03-01

    Full Text Available The large number of mechanical degrees of freedom of the hand is not fully exploited during actual movements such as grasping. Usually, angular movements in various joints tend to be coupled, and EMG activities in different hand muscles tend to be correlated. The occurrence of covariation in the former was termed kinematic synergies, in the latter muscle synergies. This study addresses two questions: (i Whether kinematic and muscle synergies can simultaneously accommodate for kinematic and kinetic constraints. (ii If so, whether there is an interrelation between kinematic and muscle synergies. We used a reach-grasp-and-pull paradigm and recorded the hand kinematics as well as 8 surface EMGs. Subjects had to either perform a precision grip or side grip and had to modify their grip force in order to displace an object against a low or high load. The analysis was subdivided into three epochs: reach, grasp-and-pull, and static hold. Principal component analysis (PCA, temporal or static was performed separately for all three epochs, in the kinematic and in the EMG domain. PCA revealed that (i Kinematic- and muscle-synergies can simultaneously accommodate kinematic (grip type and kinetic task constraints (load condition. (ii Upcoming grip and load conditions of the grasp are represented in kinematic- and muscle-synergies already during reach. Phase plane plots of the principal muscle-synergy against the principal kinematic synergy revealed (iii that the muscle-synergy is linked (correlated, and in phase advance to the kinematic synergy during reach and during grasp-and-pull. Furthermore (iv, pair-wise correlations of EMGs during hold suggest that muscle-synergies are (in part implemented by coactivation of muscles through common input. Together, these results suggest that kinematic synergies have (at least in part their origin not just in muscular activation, but in synergiestic muscle activation. In short: kinematic synergies may result from muscle

  17. Functional evaluation of natural sensory feedback incorporated in a hand grasp neuroprosthesis.

    Science.gov (United States)

    Inmann, Andreas; Haugland, Morten

    2004-07-01

    We investigated whether automatic control of a hand grasp neuroprosthesis by means of signals from natural sensors in the skin of the index finger can mimic the natural control of grasp force in an important task of daily living, namely eating. We designed a simulated eating task with the same ratio of rest and activity as was found on average in a video analysis of three meals consumed in a social environment. An instrumented fork measured grasp force as well as the force in the long axis and perpendicular to the long axis at the tip of the fork. The simulated eating task was performed by a tetraplegic volunteer using a hand grasp neuroprosthesis both with and without use of feedback from the natural sensors. Further, 10 able-bodied volunteers performed the task with the same (lateral) grasp as the tetraplegic volunteer to obtain measures for improving the control strategy of the hand grasp neuroprosthesis. We have shown that a hand grasp neuroprosthesis incorporating natural sensory feedback can to some extent mimic the natural application of grasp force on a fork during simulated eating. The mean grasp force during active phases was higher than the mean grasp force during inactive phases. The mean grasp force applied during a simulated eating task was reduced by using the system with sensory feedback compared to using the system without sensory feedback.

  18. Subjective performance evaluations and reciprocity in principal-agent relations

    DEFF Research Database (Denmark)

    Sebald, Alexander Christopher; Walzl, Markus

    2014-01-01

    . In contrast to existing models of reciprocity, we find that agents tend to sanction whenever the feedback of principals is below their subjective self-evaluations even if agents' pay-offs are independent of it. In turn, principals provide more positive feedback (relative to their actual performance assessment......We conduct a laboratory experiment with agents working on, and principals benefiting from, a real effort task in which the agents' performance can only be evaluated subjectively. Principals give subjective performance feedback to agents, and agents have an opportunity to sanction principals...

  19. Relations between subjective evaluations of memory and objective memory performance

    NARCIS (Netherlands)

    Schmidt, I.W; Berg, I.J; Deelman, B.G

    2001-01-01

    Several explanations for the weak relations between subjective memory judgments and objective memory performance were investigated in two groups of normal older adults. Group 1 sampled a general population (mean age 61.6 yr., range 46-891, while Group 2 sampled subjects who were on a waiting Est for

  20. Stereovision system for estimation of the grasp type for electrotherapy

    Directory of Open Access Journals (Sweden)

    Štrbac Matija

    2011-01-01

    Full Text Available This paper presents hardware and software for scene analysis that are designed for the system used in treatment of post stroke hemiplegic patients using electrical stimulation. New hardware includes two cameras and a laser pointer, while new software is given as a Matlab program that performs real-time estimate of size and shape of targeted object. Based on heuristic contemplation the system makes a decision grasp type and necessary actions for the purpose of hand opening and closing. The system was tested on 13 objects and in 95% of cases it worked according to demands, i.e. corresponding to choices of healthy subjects when they wanted to grab that same object.

  1. Performance of Pekin ducks subjected to qualitative feed restriction ...

    African Journals Online (AJOL)

    Performance of Pekin ducks subjected to qualitative feed restriction at various ages during the rearing period. Different diets low in lysine were fed to ducklings of various ages in three separate trials to investigate the effect of these diets on bodymass and subsequent reproductive performance. The results showed that when ...

  2. Optimal contracts based on subjective performance evaluations and reciprocity

    DEFF Research Database (Denmark)

    Sebald, Alexander Christopher; Walzl, Markus

    2015-01-01

    As demonstrated in a recent laboratory experiment (see Sebald & Walzl, 2014), individuals tend to sanction others who subjectively evaluate their performance whenever this assessment falls short of the individuals’ self-evaluation. Interestingly, this is the case even if the individuals’ earnings...... are unaffected by the subjective performance appraisal. Hence, performance feedback which falls short of agents’ self- evaluations can be interpreted as an unkind act that triggers a negatively reciprocal response not only if the assessment determines agents’ earnings but also when it lacks monetary consequences...

  3. Online kinematic regulation by visual feedback for grasp versus transport during reach-to-pinch.

    Science.gov (United States)

    Nataraj, Raviraj; Pasluosta, Cristian; Li, Zong-Ming

    2014-08-01

    This study investigated novel kinematic performance parameters to understand regulation by visual feedback (VF) of the reaching hand on the grasp and transport components during the reach-to-pinch maneuver. Conventional metrics often signify discrete movement features to postulate sensory-based control effects (e.g., time for maximum velocity to signify feedback delay). The presented metrics of this study were devised to characterize relative vision-based control of the sub-movements across the entire maneuver. Movement performance was assessed according to reduced variability and increased efficiency of kinematic trajectories. Variability was calculated as the standard deviation about the observed mean trajectory for a given subject and VF condition across kinematic derivatives for sub-movements of inter-pad grasp (distance between thumb and index finger-pads; relative orientation of finger-pads) and transport (distance traversed by wrist). A Markov analysis then examined the probabilistic effect of VF on which movement component exhibited higher variability over phases of the complete maneuver. Jerk-based metrics of smoothness (minimal jerk) and energy (integrated jerk-squared) were applied to indicate total movement efficiency with VF. The reductions in grasp variability metrics with VF were significantly greater (pjerk, suggesting separate control pathways for each component. The Markov analysis indicated that VF preferentially regulates grasp over transport when continuous control is modeled probabilistically during the movement. Efficiency measures demonstrated VF to be more integral for early motor planning of grasp than transport in producing greater increases in smoothness and trajectory adjustments (i.e., jerk-energy) early compared to late in the movement cycle. These findings demonstrate the greater regulation by VF on kinematic performance of grasp compared to transport and how particular features of this relativistic control occur continually over the

  4. Neural correlates of action perception at the onset of functional grasping.

    Science.gov (United States)

    Bakker, Marta; Daum, Moritz M; Handl, Andrea; Gredebäck, Gustaf

    2015-06-01

    Event-related potentials were recorded while infants observe congruent or incongruent grasping actions at the age when organized grasping first emerges (4-6 months of age). We demonstrate that the event-related potential component P400 encodes the congruency of power grasps at the age of 6 months (Experiment 1) and in 5-month-old infants that have developed the ability to use power grasps (Experiment 2). This effect does not extend to precision grasps, which infants cannot perform (Experiment 3). Our findings suggest that infants' encoding of the relationship between an object and a grasping hand (the action-perception link) is highly specialized to actions and manual configurations of actions that infants are able to perform. © The Author (2014). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  5. Grasping Pattern Recognition and Grasping Force Estimation For Prosthetic Hands

    Directory of Open Access Journals (Sweden)

    Zhang Bing-Ke

    2016-01-01

    Full Text Available Human’s movement can be decoded by surface electromyography (EMG, and the prosthetic hand can be controlled freely through EMG signal. This paper proposes a grasping pattern and force synchronized decoding method for prosthetic hands. Considering pattern recognition and force estimation simultaneously, this paper analyzes whether different muscle contraction levels affect pattern recognition and whether different grasping modes have impact on force estimation, then proposes two schemes to complete EMG simultaneously decoding. Experiments compare the accuracy of the two methods. The results show that there is no much difference between two methods in force estimation, the former’s accuracy of pattern recognition is a little higher than the latter.

  6. Visual Field Preferences of Object Analysis for Grasping with One Hand

    Directory of Open Access Journals (Sweden)

    Ada eLe

    2014-10-01

    Full Text Available When we grasp an object using one hand, the opposite hemisphere predominantly guides the motor control of grasp movements (Davare et al. 2007; Rice et al. 2007. However, it is unclear whether visual object analysis for grasp control relies more on inputs (a from the contralateral than the ipsilateral visual field, (b from one dominant visual field regardless of the grasping hand, or (c from both visual fields equally. For bimanual grasping of a single object we have recently demonstrated a visual field preference for the left visual field (Le and Niemeier 2013a, 2013b, consistent with a general right-hemisphere dominance for sensorimotor control of bimanual grasps (Le et al., 2013. But visual field differences have never been tested for unimanual grasping. Therefore, here we asked right-handed participants to fixate to the left or right of an object and then grasp the object either with their right or left hand using a precision grip. We found that participants grasping with their right hand performed better with objects in the right visual field: maximum grip apertures (MGAs were more closely matched to the object width and were smaller than for objects in the left visual field. In contrast, when people grasped with their left hand, preferences switched to the left visual field. What is more, MGA scaling showed greater visual field differences compared to right-hand grasping. Our data suggest that, visual object analysis for unimanual grasping shows a preference for visual information from the ipsilateral visual field, and that the left hemisphere is better equipped to control grasps in both visual fields.

  7. Performance, Pinned Down: A Lacanian Analysis of Subjectivity at Work

    NARCIS (Netherlands)

    C.M.W. Hoedemaekers (Casper)

    2008-01-01

    textabstractThis study seeks to create an account of how the performing subject comes into being within a specific organizational context. It looks at some of the ways in which managerial practices impact upon the selfhood of employees by means of the language in which they are couched. Drawing

  8. Shaping of Reach-to-Grasp Kinematics by Intentions: A Meta-Analysis

    DEFF Research Database (Denmark)

    Egmose, Ida; Køppe, Simo

    2017-01-01

    a restricted maximum likelihood random effect model. The meta-analyses showed that changes in both object properties and prior intentions affected reach-to-grasp kinematics. Based on these results, the authors argue for a tripartition of the reach-to-grasp movement in which the accelerating part of the reach......When we reach to grasp something, we need to take into account both the properties of the object we are grasping and the intention we have in mind. Previous research has found these constraints to be visible in the reach-to-grasp kinematics, but there is no consensus on which kinematic parameters...... are the most sensitive. To examine this, a systematic literature search and meta-analyses were performed. The search identified studies assessing how changes in either an object property or a prior intention affect reach-to-grasp kinematics in healthy participants. Hereafter, meta-analyses were conducted using...

  9. Grasping Claws of Bionic Climbing Robot for Rough Wall Surface: Modeling and Analysis

    Directory of Open Access Journals (Sweden)

    Quansheng Jiang

    2017-12-01

    Full Text Available Aiming at the inspection of rough stone and concrete wall surfaces, a grasping module of cross-arranged claw is designed. It can attach onto rough wall surfaces by hooking or grasping walls. First, based on the interaction mechanism of hooks and rough wall surfaces, the hook structures in claw tips are developed. Then, the size of the hook tip is calculated and the failure mode is analyzed. The effectiveness and reliability of the mechanism are verified through simulation and finite element analysis. Afterwards, the prototype of the grasping module of claw is established to carry out grasping experiment on vibrating walls. Finally, the experimental results demonstrate that the proposed cross-arranged claw is able to stably grasp static wall surfaces and perform well in grasping vibrating walls, with certain anti-rollover capability. This research lays a foundation for future researches on wall climbing robots with vibrating rough wall surfaces.

  10. An empirical study of single-query motion planning for grasp execution

    NARCIS (Netherlands)

    Meijer, Jonathan; Lei, Q.; Wisse, M.; Buss, Martin; Sawodny, Oliver

    2017-01-01

    This paper identifies high-performing Open Motion Planning Library (OMPL) planners for grasp execution and simultaneously presents useful benchmark data. Four grasp executions were defined using a UR5 manipulator. The performance was measured by means of solved runs, computing time and path

  11. Ground Robotic Hand Applications for the Space Program study (GRASP)

    Science.gov (United States)

    Grissom, William A.; Rafla, Nader I. (Editor)

    1992-01-01

    This document reports on a NASA-STDP effort to address research interests of the NASA Kennedy Space Center (KSC) through a study entitled, Ground Robotic-Hand Applications for the Space Program (GRASP). The primary objective of the GRASP study was to identify beneficial applications of specialized end-effectors and robotic hand devices for automating any ground operations which are performed at the Kennedy Space Center. Thus, operations for expendable vehicles, the Space Shuttle and its components, and all payloads were included in the study. Typical benefits of automating operations, or augmenting human operators performing physical tasks, include: reduced costs; enhanced safety and reliability; and reduced processing turnaround time.

  12. Distinct neural patterns enable grasp types decoding in monkey dorsal premotor cortex

    Science.gov (United States)

    Hao, Yaoyao; Zhang, Qiaosheng; Controzzi, Marco; Cipriani, Christian; Li, Yue; Li, Juncheng; Zhang, Shaomin; Wang, Yiwen; Chen, Weidong; Chiara Carrozza, Maria; Zheng, Xiaoxiang

    2014-12-01

    Objective. Recent studies have shown that dorsal premotor cortex (PMd), a cortical area in the dorsomedial grasp pathway, is involved in grasp movements. However, the neural ensemble firing property of PMd during grasp movements and the extent to which it can be used for grasp decoding are still unclear. Approach. To address these issues, we used multielectrode arrays to record both spike and local field potential (LFP) signals in PMd in macaque monkeys performing reaching and grasping of one of four differently shaped objects. Main results. Single and population neuronal activity showed distinct patterns during execution of different grip types. Cluster analysis of neural ensemble signals indicated that the grasp related patterns emerged soon (200-300 ms) after the go cue signal, and faded away during the hold period. The timing and duration of the patterns varied depending on the behaviors of individual monkey. Application of support vector machine model to stable activity patterns revealed classification accuracies of 94% and 89% for each of the two monkeys, indicating a robust, decodable grasp pattern encoded in the PMd. Grasp decoding using LFPs, especially the high-frequency bands, also produced high decoding accuracies. Significance. This study is the first to specify the neuronal population encoding of grasp during the time course of grasp. We demonstrate high grasp decoding performance in PMd. These findings, combined with previous evidence for reach related modulation studies, suggest that PMd may play an important role in generation and maintenance of grasp action and may be a suitable locus for brain-machine interface applications.

  13. Posture-based motion planning: applications to grasping.

    Science.gov (United States)

    Rosenbaum, D A; Meulenbroek, R J; Vaughan, J; Jansen, C

    2001-10-01

    This article describes a model of motion planning instantiated for grasping. According to the model, one of the most important aspects of motion planning is establishing a constraint hierarchy--a set of prioritized requirements defining the task to be performed. For grasping, constraints include avoiding collisions with to-be-grasped objects and minimizing movement-related effort. These and other constraints are combined with instance retrieval (recall of stored postures) and instance generation (generation of new postures and movements to them) to simulate flexible prehension. Dynamic deadline setting is used to regulate termination of instance generation, and performance of more than one movement at a time with a single effector is used to permit obstacle avoidance. Old and new data are accounted for with the model.

  14. Factor structure of trunk performance data for healthy subjects.

    Science.gov (United States)

    Lee, Y; Kuo, C

    2000-05-01

    To examine the factor structure of various measurements of trunk muscle performance for healthy subjects. A total of 22 performance scores were collected and their univariate and multi-variate relationships were examined. Extensive literature exists on the measurement of trunk performance data and the relationships between measurements but what needs to be collected to realize a true performance score remains unclear. Trunk muscle performance scores of 150 subjects (71 males and 79 females) were obtained on an Isostation B-200 Dynamometer. Twenty-two parameters measuring range of motion, isometric strength, velocity, and endurance on all three planes of motion were collected. The factor structures were constructed using Principal Components Analysis. Clear-cut factor patterns (explained 96.3% of the total variance) suggests that the five-factor structure might be valid and appropriate for this population. The major loading on each factor indicated that: Factor 1 could be labeled as a static strength measure; Factor 2 as velocity; Factor 3 as flexibility; and Factors 4 and 5 as fatigue-resistance. No single mode of measurement can provide a good representation of a total trunk muscle performance. RelevanceFor the realization of trunk muscle performance, clinics have to measure all modes of isometric strength, velocity, range of motion, and endurance. Care must be taken in eliminating any parameter.

  15. Association of Chronic Subjective Tinnitus with Neuro- Cognitive Performance.

    Science.gov (United States)

    Gudwani, Sunita; Munjal, Sanjay K; Panda, Naresh K; Kohli, Adarsh

    2017-12-01

    Chronic subjective tinnitus is associated with cognitive disruptions affecting perception, thinking, language, reasoning, problem solving, memory, visual tasks (reading) and attention. To evaluate existence of any association between tinnitus parameters and neuropsychological performance to explain cognitive processing. Study design was prospective, consisting 25 patients with idiopathic chronic subjective tinnitus and gave informed consent before planning their treatment. Neuropsychological profile included (i) performance on verbal information, comprehension, arithmetic and digit span; (ii) non-verbal performance for visual pattern completion analogies; (iii) memory performance for long-term, recent, delayed-recall, immediate-recall, verbal-retention, visualretention, visual recognition; (iv) reception, interpretation and execution for visual motor gestalt. Correlation between tinnitus onset duration/ loudness perception with neuropsychological profile was assessed by calculating Spearman's coefficient. Findings suggest that tinnitus may interfere with cognitive processing especially performance on digit span, verbal comprehension, mental balance, attention & concentration, immediate recall, visual recognition and visual-motor gestalt subtests. Negative correlation between neurocognitive tasks with tinnitus loudness and onset duration indicated their association. Positive correlation between tinnitus and visual-motor gestalt performance indicated the brain dysfunction. Tinnitus association with non-auditory processing of verbal, visual and visuo-spatial information suggested neuroplastic changes that need to be targeted in cognitive rehabilitation.

  16. A constrained optimization framework for compliant underactuated grasping

    Directory of Open Access Journals (Sweden)

    M. Ciocarlie

    2011-02-01

    Full Text Available This study focuses on the design and analysis of underactuated robotic hands that use tendons and compliant joints to enable passive mechanical adaptation during grasping tasks. We use a quasistatic equilibrium formulation to predict the stability of a given grasp. This method is then used as the inner loop of an optimization algorithm that can find a set of actuation mechanism parameters that optimize the stability measure for an entire set of grasps. We discuss two possible approaches to design optimization using this framework, one using exhaustive search over the parameter space, and the other using a simplified gripper construction to cast the problem to a form that is directly solvable using well-established optimization methods. Computations are performed in 3-D, allow arbitrary geometry of the grasped objects and take into account frictional constraints.

    This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010, 19 August 2010, Montréal, Canada.

  17. Repeatability of grasp recognition for robotic hand prosthesis control based on sEMG data.

    Science.gov (United States)

    Palermo, Francesca; Cognolato, Matteo; Gijsberts, Arjan; Muller, Henning; Caputo, Barbara; Atzori, Manfredo

    2017-07-01

    Control methods based on sEMG obtained promising results for hand prosthetics. Control system robustness is still often inadequate and does not allow the amputees to perform a large number of movements useful for everyday life. Only few studies analyzed the repeatability of sEMG classification of hand grasps. The main goals of this paper are to explore repeatability in sEMG data and to release a repeatability database with the recorded experiments. The data are recorded from 10 intact subjects repeating 7 grasps 12 times, twice a day for 5 days. The data are publicly available on the Ninapro web page. The analysis for the repeatability is based on the comparison of movement classification accuracy in several data acquisitions and for different subjects. The analysis is performed using mean absolute value and waveform length features and a Random Forest classifier. The accuracy obtained by training and testing on acquisitions at different times is on average 27.03% lower than training and testing on the same acquisition. The results obtained by training and testing on different acquisitions suggest that previous acquisitions can be used to train the classification algorithms. The inter-subject variability is remarkable, suggesting that specific characteristics of the subjects can affect repeatibility and sEMG classification accuracy. In conclusion, the results of this paper can contribute to develop more robust control systems for hand prostheses, while the presented data allows researchers to test repeatability in further analyses.

  18. Motor imagery practice for improving sit to stand and reaching to grasp in individuals with poststroke hemiparesis.

    Science.gov (United States)

    Guttman, Avia; Burstin, Arie; Brown, Riki; Bril, Shai; Dickstein, Ruth

    2012-01-01

    Motor imagery practice refers to the mental rehearsal of motor acts in the absence of actual movement production. To evaluate the effect of motor imagery practice on the performance of sit to stand (STS) and reaching to grasp in subjects with post stroke chronic hemiparesis. The study was designed as a crossover intervention. Participants were 13 individuals (mean age, 68.9 [±4.9] years) with chronic hemiparesis enrolled in a day center at the Bet-Rivka Rehabilitation Hospital in Petach Tikvah, Israel. Following 1 week of baseline measurements of the performance of STS and reaching to grasp, these functions were mentally practiced for 15 minutes 3 times a week for 4 weeks. Half of the subjects mentally practiced STS, while the other half practiced the reaching imagery protocol. Subsequently, the participants in each group crossed over to practice the second function for the next 4 weeks. All practice sessions were performed according to a pre-established protocol under supervision. Measurements of real performance took place twice before and twice immediately following each practice session. For STS, the Tetrax Balance System was used to measure the speed of performance and weight distribution between the legs. Reaching to grasp was appraised via a "kinematic" glove and included speed variables of the hand. A significant decrease was found in the values of STS duration. Weight distribution between the legs was not affected by the intervention. For reaching to grasp, a significant improvement was found in the mean and the maximum reaching velocity. In individuals with chronic hemiparesis, the imagery practice of meaningful motor tasks can positively affect real performance.

  19. Which one Enhances Muscular Performance in ACL Reconstructed Subjects

    Science.gov (United States)

    Harput, Gulcan; Ulusoy, Burak; Atay, Ahmet Ozgur; Baltacı, Gul

    2014-01-01

    Objectives: The aim of this study was to investigate the effects of functional knee brace and kinesiotaping on muscular performance in anterior cruciate ligament reconstructed subjects who reached return to sport phase of the rehabilitation. Methods: Twenty (17 males, 3 females, Age: 24.7±7.1 years, Body weight: 74.4±12.0 kg, Height: 177.9±6.5 cm, BMI: 23.9±3.6 kg/m2) subjects who underwent anterior cruciate ligament reconstruction by using hamstring tendon auto graft were included in this study. When the subjects reached the return to sports phase of rehabilitation which was 6th months after surgery, knee muscle strength, jump performance and balance tests were performed 3 times: bare, with knee brace and with kinesio taping. The order of the tests were randomized to eliminate the effects of fatigue and motor learning. Quadriceps and hamstring muscle strength was measured on an isokinetic dynamometer at 180 °/s and 60°/s angular velocities. Vertical Jump (VJ) and One Leg Hop Tests (OLHT) were used to assess jump performance. Star Excursion Balance Test (SEBT) with anterior, posteromedial and posterolateral reach distance was used to assess the dynamic balance. When all tests were performed, the subjects were asked under which test condition they felt more confident. Repeated measures of ANOVA was used to analyze the difference among three test conditions (bare, kinesiotaping, knee brace). Bonferroni post hoc test was used for pairwise comparison. Results: SEBT posteromedial (PM)and posterolateral (PL) reach distances were found significantly different among three test conditions(PM: F(2,38)=3.42,p=0.04), PL: F(2,38)=4.37,p=0.02). Kinesiotaping increased posteromedial reach distance (p=0.03). On the other hand, brace decreased posterolateral reach distance (p=0.04). VJ and OLHT performance were also found significantly different between three test conditions (VJ: F (2,38)=3.44,p=0.04, OLHT: (F(2,38)=4.04,p=0.02). Kinesio taping increased one leg hop distance

  20. Quality of Grasping and the Role of Haptics in a 3-D Immersive Virtual Reality Environment in Individuals With Stroke.

    Science.gov (United States)

    Levin, Mindy F; Magdalon, Eliane C; Michaelsen, Stella M; Quevedo, Antonio A F

    2015-11-01

    Reaching and grasping parameters with and without haptic feedback were characterized in people with chronic post-stroke behaviors. Twelve (67 ± 10 years) individuals with chronic stroke and arm/hand paresis (Fugl-Meyer Assessment-Arm: ≥ 46/66 pts) participated. Three dimensional (3-D) temporal and spatial kinematics of reaching and grasping movements to three objects (can: cylindrical grasp; screwdriver: power grasp; pen: precision grasp) in a physical environment (PE) with and without additional haptic feedback and a 3-D virtual environment (VE) with haptic feedback were recorded. Participants reached, grasped and transported physical and virtual objects using similar movement strategies in all conditions. Reaches made in VE were less smooth and slower compared to the PE. Arm and trunk kinematics were similar in both environments and glove conditions. For grasping, stroke subjects preserved aperture scaling to object size but used wider hand apertures with longer delays between times to maximal reaching velocity and maximal grasping aperture. Wearing the glove decreased reaching velocity. Our results in a small group of subjects suggest that providing haptic information in the VE did not affect the validity of reaching and grasping movement. Small disparities in movement parameters between environments may be due to differences in perception of object distance in VE. Reach-to-grasp kinematics to smaller objects may be improved by better 3-D rendering. Comparable kinematics between environments and conditions is encouraging for the incorporation of high quality VEs in rehabilitation programs aimed at improving upper limb recovery.

  1. Passive reach and grasp with functional electrical stimulation and robotic arm support

    NARCIS (Netherlands)

    Westerveld, Ard J.; Schouten, Alfred C.; Veltink, Peter H.; van der Kooij, Herman

    2014-01-01

    Rehabilitation of arm and hand function is crucial to increase functional independence of stroke subjects. Here, we investigate the technical feasibility of an integrated training system combining robotics and functional electrical stimulation (FES) to support reach and grasp during functional

  2. A Biologically Inspired Learning to Grasp System

    Science.gov (United States)

    2001-10-25

    contact the object. (adapted from [2]) The macaque inferior premotor cortex has been identified as being involved in reaching and grasping movements [3... motoneuronal system, which has not been developed by the age of reflex grasping and early voluntary grasping [7]. Therefore, it is unlikely that the...Camarda, L. Fogassi, M. Gentilucci, G. Luppino, M. Matelli. “Functional Organization of Inferior Area 6 in the Macaque Monkey II. Area F5 and the

  3. Real-time vision, tactile cues, and visual form agnosia in pantomimed grasping: removing haptic feedback induces a switch from natural to pantomime-like grasps

    Directory of Open Access Journals (Sweden)

    Robert Leslie Whitwell

    2015-05-01

    Full Text Available Investigators study the kinematics of grasping movements (prehension under a variety of conditions to probe visuomotor function in normal and brain-damaged individuals. When patient DF, who suffers from visual form agnosia, performs natural grasps, her in-flight hand aperture is scaled to the widths of targets ('grip scaling' that she cannot discriminate amongst. In contrast, when DF's pantomime grasps are based on a memory of a previewed object, her grip scaling is very poor. Her failure on this task has been interpreted as additional support for the dissociation between the use of object vision for action and object vision for perception. Curiously, however, when DF directs her pantomimed grasps towards a displaced imagined copy of a visible object where her fingers make contact with the surface of the table, her grip scaling does not appear to be particularly poor. In the first of two experiments, we revisit this previous work and show that her grip scaling in this real-time pantomime grasping task does not differ from controls, suggesting that terminal tactile feedback from a proxy of the target can maintain DF's grip scaling. In a second experiment with healthy participants, we tested a recent variant of a grasping task in which no tactile feedback is available (i.e. no haptic feedback by comparing the kinematics of target-directed grasps with and without haptic feedback to those of real-time pantomime grasps without haptic feedback. Compared to natural grasps, removing haptic feedback increased RT, slowed the velocity of the reach, reduced grip aperture, sharpened the slopes relating grip aperture to target width, and reduced the final grip aperture. All of these effects were also observed in the pantomime grasping task. Taken together, these results provide compelling support for the view that removing haptic feedback induces a switch from real-time visual control to one that depends more on visual perception and cognitive supervision.

  4. Deep learning-based artificial vision for grasp classification in myoelectric hands.

    Science.gov (United States)

    Ghazaei, Ghazal; Alameer, Ali; Degenaar, Patrick; Morgan, Graham; Nazarpour, Kianoush

    2017-06-01

    Computer vision-based assistive technology solutions can revolutionise the quality of care for people with sensorimotor disorders. The goal of this work was to enable trans-radial amputees to use a simple, yet efficient, computer vision system to grasp and move common household objects with a two-channel myoelectric prosthetic hand. We developed a deep learning-based artificial vision system to augment the grasp functionality of a commercial prosthesis. Our main conceptual novelty is that we classify objects with regards to the grasp pattern without explicitly identifying them or measuring their dimensions. A convolutional neural network (CNN) structure was trained with images of over 500 graspable objects. For each object, 72 images, at [Formula: see text] intervals, were available. Objects were categorised into four grasp classes, namely: pinch, tripod, palmar wrist neutral and palmar wrist pronated. The CNN setting was first tuned and tested offline and then in realtime with objects or object views that were not included in the training set. The classification accuracy in the offline tests reached [Formula: see text] for the seen and [Formula: see text] for the novel objects; reflecting the generalisability of grasp classification. We then implemented the proposed framework in realtime on a standard laptop computer and achieved an overall score of [Formula: see text] in classifying a set of novel as well as seen but randomly-rotated objects. Finally, the system was tested with two trans-radial amputee volunteers controlling an i-limb UltraTM prosthetic hand and a motion controlTM prosthetic wrist; augmented with a webcam. After training, subjects successfully picked up and moved the target objects with an overall success of up to [Formula: see text]. In addition, we show that with training, subjects' performance improved in terms of time required to accomplish a block of 24 trials despite a decreasing level of visual feedback. The proposed design constitutes a

  5. Ethographic ubiquity: original fake, expanded codex, transurban subject, performative doll

    Directory of Open Access Journals (Sweden)

    Massimo Canevacci

    2012-12-01

    Full Text Available My essay presents the emerging of fake as a concept that does not mean false, but a post-dualistic mix of false/truth. The relation between digital culture and ubiquitous subjectivity is fundamental during its process; in the same way, the relation between aura and reproducibility cannot be determined dialectically as Benjamin did. Digital auratic reproducibility is the contemporary context and communicational metropolis is characterized by spontaneous and public performance: so, my conclusion is an analysis of some “living” doll and their uncanny presence.

  6. An opportunity cost model of subjective effort and task performance.

    Science.gov (United States)

    Kurzban, Robert; Duckworth, Angela; Kable, Joseph W; Myers, Justus

    2013-12-01

    Why does performing certain tasks cause the aversive experience of mental effort and concomitant deterioration in task performance? One explanation posits a physical resource that is depleted over time. We propose an alternative explanation that centers on mental representations of the costs and benefits associated with task performance. Specifically, certain computational mechanisms, especially those associated with executive function, can be deployed for only a limited number of simultaneous tasks at any given moment. Consequently, the deployment of these computational mechanisms carries an opportunity cost--that is, the next-best use to which these systems might be put. We argue that the phenomenology of effort can be understood as the felt output of these cost/benefit computations. In turn, the subjective experience of effort motivates reduced deployment of these computational mechanisms in the service of the present task. These opportunity cost representations, then, together with other cost/benefit calculations, determine effort expended and, everything else equal, result in performance reductions. In making our case for this position, we review alternative explanations for both the phenomenology of effort associated with these tasks and for performance reductions over time. Likewise, we review the broad range of relevant empirical results from across sub-disciplines, especially psychology and neuroscience. We hope that our proposal will help to build links among the diverse fields that have been addressing similar questions from different perspectives, and we emphasize ways in which alternative models might be empirically distinguished.

  7. Object grasping by combining caging and force closure

    NARCIS (Netherlands)

    Lei, Q.; Wisse, M.

    2016-01-01

    The current research trends of object grasping can be summarized as caging grasping and force closure grasping. The motivation of this paper is to combine the advantage of caging grasping and force closure grasping to enable under-actuated grippers like the Lacquey gripper and the parallel

  8. Continuous decoding of human grasp kinematics using epidural and subdural signals

    Science.gov (United States)

    Flint, Robert D.; Rosenow, Joshua M.; Tate, Matthew C.; Slutzky, Marc W.

    2017-02-01

    Objective. Restoring or replacing function in paralyzed individuals will one day be achieved through the use of brain-machine interfaces. Regaining hand function is a major goal for paralyzed patients. Two competing prerequisites for the widespread adoption of any hand neuroprosthesis are accurate control over the fine details of movement, and minimized invasiveness. Here, we explore the interplay between these two goals by comparing our ability to decode hand movements with subdural and epidural field potentials (EFPs). Approach. We measured the accuracy of decoding continuous hand and finger kinematics during naturalistic grasping motions in five human subjects. We recorded subdural surface potentials (electrocorticography; ECoG) as well as with EFPs, with both standard- and high-resolution electrode arrays. Main results. In all five subjects, decoding of continuous kinematics significantly exceeded chance, using either EGoG or EFPs. ECoG decoding accuracy compared favorably with prior investigations of grasp kinematics (mean ± SD grasp aperture variance accounted for was 0.54 ± 0.05 across all subjects, 0.75 ± 0.09 for the best subject). In general, EFP decoding performed comparably to ECoG decoding. The 7-20 Hz and 70-115 Hz spectral bands contained the most information about grasp kinematics, with the 70-115 Hz band containing greater information about more subtle movements. Higher-resolution recording arrays provided clearly superior performance compared to standard-resolution arrays. Significance. To approach the fine motor control achieved by an intact brain-body system, it will be necessary to execute motor intent on a continuous basis with high accuracy. The current results demonstrate that this level of accuracy might be achievable not just with ECoG, but with EFPs as well. Epidural placement of electrodes is less invasive, and therefore may incur less risk of encephalitis or stroke than subdural placement of electrodes. Accurately decoding motor

  9. The influence of reducing intermediate target constraints on grasp posture planning during a three-segment object manipulation task.

    Science.gov (United States)

    Seegelke, Christian; Hughes, Charmayne M L; Knoblauch, Andreas; Schack, Thomas

    2015-02-01

    The present experiment examined the influence of final target position on grasp posture planning during a three-segment object manipulation task in which the required object orientation at the first target position was unconstrained. Participants grasped a cylindrical object from a home position, placed it at an intermediate position in a freely chosen orientation, and subsequently placed it at one of four final target positions. Considerable inter-individual differences in initial grasp selection were observed which also led to differences in final grasp postures. Whereas some participants strongly adjusted their initial grasp postures to the final target orientation, and thus showed a preference for end-state comfort, other participants showed virtually no adjustment in initial grasp postures, hence satisfying initial-state comfort. Interestingly, as intermediate grasp postures were similar regardless of initial grasp adjustment, intermediate-state comfort was prioritized by all participants. These results provide further evidence for the interaction of multiple action selection constraints in grasp posture planning during multi-segment object manipulation tasks. Whereas some constraints may take strict precedence in a given task, other constraints may be more flexible and weighted differently among participants. This differentiated weighting leads to task- and subject-specific constraint hierarchies and is reflected in inter-individual differences in grasp selection.

  10. Growth performance of pigs subjected to multiple concurrent environmental stressors.

    Science.gov (United States)

    Hyun, Y; Ellis, M; Riskowski, G; Johnson, R W

    1998-03-01

    The effects of many single stressors have been reported, but how pigs perform when subjected to more than one or two stressors at a time, as is common in commercial swine production, has not. To study this, 256 Yorkshire x Hampshire or purebred Duroc pigs (34.7+/-.5 kg) were subjected to one of the eight treatment combinations (2 x 2 x 2 factorial) of ambient temperature (constant thermoneutral [24 degrees C] or high cycling temperature [28 to 34 degrees C]), stocking density (.56 or .25 m2/pig), and social group (static group or regrouped at the start of wk 1 and 3) during a 4-wk experiment. The temperature regimens were imposed in two adjacent mechanically ventilated rooms, and each temperature was imposed in each room across two trials. Four barrows and four gilts were assigned to each of the eight pens in the two rooms, and they always had free access to water and a corn-soybean meal-based diet. Treatments were imposed after a 7-d acclimation period at 24 degrees C and .56 m2/pig. Weight gain and feed intake were measured weekly. The main effects of each of the stressors for 4-wk ADG and ADFI were significant (P stressor interactions for ADG, ADFI, and gain:feed (G:F), there were no significant three-way interactions and only six two-way interactions, suggesting that the effects of the individual stressors were additive. Accordingly, the growth rate of pigs subjected to the single stressor of high cycling temperature, restricted space allowance, or regrouping was depressed 10, 16, and 11%, respectively, and ADG of pigs subjected to all three stressors simultaneously was depressed by 31%. Stressor additivity was further corroborated by examining the effect of stressor order, or the number of stressors imposed simultaneously. As the number of stressors increased from 0 to 3, ADG, ADFI, and G:F decreased linearly. These data suggest that multiple concurrent stressors affect growth performance of pigs in a predictable fashion (i.e., additively) and indicate that

  11. On Transferability of grasp-affordances in data-driven grasping

    DEFF Research Database (Denmark)

    Rytz, Jimmy Alison; Ellekilde, Lars-Peter; Kraft, Dirk

    2013-01-01

    It has become a common practice to use simulation to generate large databases of good grasps for grasp planning in robotics research. However, the existence of a generic simulation context that enables generation of high quality grasps that can be used in several different contexts such as bin-picking...... or picking objects from a table, has to our knowledge not been discussed in the literature. In this paper we investigate how well the quality of grasps simulated in a commonly used ”generic” context transfer to a specific context where the object is placed on a table. We generate a large database of grasp...

  12. Fast grasping of unknown objects using cylinder searching on a single point cloud

    Science.gov (United States)

    Lei, Qujiang; Wisse, Martijn

    2017-03-01

    Grasping of unknown objects with neither appearance data nor object models given in advance is very important for robots that work in an unfamiliar environment. The goal of this paper is to quickly synthesize an executable grasp for one unknown object by using cylinder searching on a single point cloud. Specifically, a 3D camera is first used to obtain a partial point cloud of the target unknown object. An original method is then employed to do post treatment on the partial point cloud to minimize the uncertainty which may lead to grasp failure. In order to accelerate the grasp searching, surface normal of the target object is then used to constrain the synthetization of the cylinder grasp candidates. Operability analysis is then used to select out all executable grasp candidates followed by force balance optimization to choose the most reliable grasp as the final grasp execution. In order to verify the effectiveness of our algorithm, Simulations on a Universal Robot arm UR5 and an under-actuated Lacquey Fetch gripper are used to examine the performance of this algorithm, and successful results are obtained.

  13. Grasp Algorithms For Optotactile Robotic Sample Acquisition Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Robotic sample acquisition is basically grasping. Multi-finger robot sample grasping devices are controlled to securely pick up samples. While optimal grasps for...

  14. Deep learning-based artificial vision for grasp classification in myoelectric hands

    Science.gov (United States)

    Ghazaei, Ghazal; Alameer, Ali; Degenaar, Patrick; Morgan, Graham; Nazarpour, Kianoush

    2017-06-01

    Objective. Computer vision-based assistive technology solutions can revolutionise the quality of care for people with sensorimotor disorders. The goal of this work was to enable trans-radial amputees to use a simple, yet efficient, computer vision system to grasp and move common household objects with a two-channel myoelectric prosthetic hand. Approach. We developed a deep learning-based artificial vision system to augment the grasp functionality of a commercial prosthesis. Our main conceptual novelty is that we classify objects with regards to the grasp pattern without explicitly identifying them or measuring their dimensions. A convolutional neural network (CNN) structure was trained with images of over 500 graspable objects. For each object, 72 images, at {{5}\\circ} intervals, were available. Objects were categorised into four grasp classes, namely: pinch, tripod, palmar wrist neutral and palmar wrist pronated. The CNN setting was first tuned and tested offline and then in realtime with objects or object views that were not included in the training set. Main results. The classification accuracy in the offline tests reached 85 % for the seen and 75 % for the novel objects; reflecting the generalisability of grasp classification. We then implemented the proposed framework in realtime on a standard laptop computer and achieved an overall score of 84 % in classifying a set of novel as well as seen but randomly-rotated objects. Finally, the system was tested with two trans-radial amputee volunteers controlling an i-limb UltraTM prosthetic hand and a motion controlTM prosthetic wrist; augmented with a webcam. After training, subjects successfully picked up and moved the target objects with an overall success of up to 88 % . In addition, we show that with training, subjects’ performance improved in terms of time required to accomplish a block of 24 trials despite a decreasing level of visual feedback. Significance. The proposed design constitutes a substantial

  15. Improvement and Neuroplasticity after Combined Rehabilitation to Forced Grasping

    Directory of Open Access Journals (Sweden)

    Michiko Arima

    2017-01-01

    Full Text Available The grasp reflex is a distressing symptom but the need to treat or suppress it has rarely been discussed in the literature. We report the case of a 17-year-old man who had suffered cerebral infarction of the right putamen and temporal lobe 10 years previously. Forced grasping of the hemiparetic left upper limb was improved after a unique combined treatment. Botulinum toxin type A (BTX-A was first injected into the left biceps, wrist flexor muscles, and finger flexor muscles. Forced grasping was reduced along with spasticity of the upper limb. In addition, repetitive facilitative exercise and object-related training were performed under low-amplitude continuous neuromuscular electrical stimulation. Since this 2-week treatment improved upper limb function, we compared brain activities, as measured by near-infrared spectroscopy during finger pinching, before and after the combined treatment. Brain activities in the ipsilesional sensorimotor cortex (SMC and medial frontal cortex (MFC during pinching under electrical stimulation after treatment were greater than those before. The results suggest that training under electrical stimulation after BTX-A treatment may modulate the activities of the ipsilesional SMC and MFC and lead to functional improvement of the affected upper limb with forced grasping.

  16. Working memory performance and thalamus microstructure in healthy subjects.

    Science.gov (United States)

    Piras, F; Caltagirone, C; Spalletta, G

    2010-12-01

    Research on the neural basis of working memory (WM) has generally focused on cortical regions, specifically frontal and parietal areas. Comparatively, evidence of a possible involvement of deep gray matter structures, that are parts of cortico-cortical circuits linking anterior and posterior cortical areas, is far less clear. The goal of the present study is to test the hypothesis that individual structural variations within deep gray matter structures may affect the cortical networks involved in WM. To this aim, a large sample (n=181) of healthy subjects underwent a high-resolution structural magnetic resonance imaging (MRI) and a diffusion tensor imaging (DTI) scan protocol. Data of micro- (mean diffusivity, MD) and macro- (volume) structural variations of six bilateral deep gray matter structures (thalamus, caudate nucleus, putamen, hippocampus, amygdala and pallidum) and lateral ventriculi volume were analyzed in association with score in a WM (the so-called n-back task) and other neuropsychological tasks. Results showed that increased MD of bilateral thalami was the only structural parameter that significantly correlated with reduced WM performance. In particular, a voxel-by-voxel analysis revealed that the greater percentage of voxels showing significant anticorrelation between WM score and MD values were localized in those thalamic nuclei projecting to prefrontal and posterior parietal cortices. Results highlight the specific involvement of thalamus microstructure, not volume, in modulating WM performance, possibly by regulating the connections among cortical areas that are recruited during WM tasks. Copyright © 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

  17. Viscoelastic performance of dielectric elastomer subject to different voltage stimulation

    Science.gov (United States)

    Sheng, Junjie; Zhang, Yuqing; Liu, Lei; Li, Bo; Chen, Hualing

    2017-04-01

    Dielectric elastomer (DE) is capable of giant deformation subject to an electric field, and demonstrates significant advantages in the potentially application of soft machines with muscle-like characteristics. Due to an inherent property of all macromolecular materials, DE exhibits strong viscoelastic properties. Viscoelasticity could cause a time-dependent deformation and lower the response speed and energy conversion efficiency of DE based actuators, thus strongly affect its electromechanical performance and applications. Combining with the rheological model of viscoelastic relaxation, the viscoelastic performance of a VHB membrane in a circular actuator configuration undergoing separately constant, ramp and sinusoidal voltages are analyzed both theoretically and experimentally. The theoretical results indicated that DE could attain a big deformation under a small constant voltage with a longer time or under a big voltage with a shorter time. The model also showed that a higher critical stretch could be achieved by applying ramping voltage with a lower rate and the stretch magnitude under sinusoidal voltage is much larger at a relatively low frequency. Finally, experiments were designed to validate the simulation and show well consistent with the simulation results.

  18. One digit interruption: the altered force patterns during functionally cylindrical grasping tasks in patients with trigger digits.

    Directory of Open Access Journals (Sweden)

    Po-Tsun Chen

    Full Text Available Most trigger digit (TD patients complain that they have problems using their hand in daily or occupational tasks due to single or multiple digits being affected. Unfortunately, clinicians do not know much about how this disease affects the subtle force coordination among digits during manipulation. Thus, this study examined the differences in force patterns during cylindrical grasp between TD and healthy subjects. Forty-two TD patients with single digit involvement were included and sorted into four groups based on the involved digits, including thumb, index, middle and ring fingers. Twelve healthy subjects volunteered as healthy controls. Two testing tasks, holding and drinking, were performed by natural grasping with minimal forces. The relations between the force of the thumb and each finger were examined by Pearson correlation coefficients. The force amount and contribution of each digit were compared between healthy controls and each TD group by the independent t test. The results showed all TD groups demonstrated altered correlation patterns of the thumb relative to each finger. Larger forces and higher contributions of the index finger were found during holding by patients with index finger involved, and also during drinking by patients with affected thumb and with affected middle finger. Although no triggering symptom occurred during grasping, the patients showed altered force patterns which may be related to the role of the affected digit in natural grasping function. In conclusion, even if only one digit was affected, the subtle force coordination of all the digits was altered during simple tasks among the TD patients. This study provides the information for the future studies to further comprehend the possible injuries secondary to the altered finger coordination and also to adopt suitable treatment strategies.

  19. Learning to Grasp Unknown Objects Based on 3D Edge Information

    DEFF Research Database (Denmark)

    Bodenhagen, Leon; Kraft, Dirk; Popovic, Mila

    2010-01-01

    an offline or an online learning scheme. Both methods are implemented using a hybrid artificial neural network containing standard nodes with a sigmoid activation function and nodes with a radial basis function. We show that a significant performance improvement can be achieved.......In this work we refine an initial grasping behavior based on 3D edge information by learning. Based on a set of autonomously generated evaluated grasps and relations between the semi-global 3D edges, a prediction function is learned that computes a likelihood for the success of a grasp using either...

  20. Decoding Information for Grasping from the Macaque Dorsomedial Visual Stream.

    Science.gov (United States)

    Filippini, Matteo; Breveglieri, Rossella; Akhras, M Ali; Bosco, Annalisa; Chinellato, Eris; Fattori, Patrizia

    2017-04-19

    Neurodecoders have been developed by researchers mostly to control neuroprosthetic devices, but also to shed new light on neural functions. In this study, we show that signals representing grip configurations can be reliably decoded from neural data acquired from area V6A of the monkey medial posterior parietal cortex. Two Macaca fascicularis monkeys were trained to perform an instructed-delay reach-to-grasp task in the dark and in the light toward objects of different shapes. Population neural activity was extracted at various time intervals on vision of the objects, the delay before movement, and grasp execution. This activity was used to train and validate a Bayes classifier used for decoding objects and grip types. Recognition rates were well over chance level for all the epochs analyzed in this study. Furthermore, we detected slightly different decoding accuracies, depending on the task's visual condition. Generalization analysis was performed by training and testing the system during different time intervals. This analysis demonstrated that a change of code occurred during the course of the task. Our classifier was able to discriminate grasp types fairly well in advance with respect to grasping onset. This feature might be important when the timing is critical to send signals to external devices before the movement start. Our results suggest that the neural signals from the dorsomedial visual pathway can be a good substrate to feed neural prostheses for prehensile actions.SIGNIFICANCE STATEMENT Recordings of neural activity from nonhuman primate frontal and parietal cortex have led to the development of methods of decoding movement information to restore coordinated arm actions in paralyzed human beings. Our results show that the signals measured from the monkey medial posterior parietal cortex are valid for correctly decoding information relevant for grasping. Together with previous studies on decoding reach trajectories from the medial posterior parietal

  1. A novel device for grasping assessment during functional tasks: preliminary results

    Directory of Open Access Journals (Sweden)

    Ana Carolinne Portela Rocha

    2016-02-01

    Full Text Available This paper presents a methodology and first results obtained in a study with a novel device that allows the analysis of grasping quality. Such a device is able to acquire motion information of upper limbs allowing kinetic of manipulation analysis as well. A pilot experiment was carried out with six groups of typically developing children aged between 5 and 10 years old, with 7-8 children in each one. The device, designed to emulate a glass, has an optical system composed by one digital camera and a special convex mirror that together allow image acquisition of grasping hand posture when it is grasped and manipulated. It also carries an Inertial Measurement Unit (IMU that captures motion data as acceleration, orientation, and angular velocities. The novel instrumented object is used in our approach to evaluate functional tasks performance in quantitative terms. During tests each child was invited to grasp the cylindrical part of the device that was placed on the top of a table, simulating the task of drinking a glass of water. In the sequence the child was oriented to transport the device back to the starting position and release it. The task was repeated 3 times for each child. A grasping hand posture evaluation is presented as an example to evaluate grasping quality. Additionally, motion patterns obtained with the triasl performed with the different groups are presented and discussed. This device is attractive due to its portable characteristics, the small size and its ability to evaluate grasping form. The results may be also useful to analyze the evolution of the rehabilitation process through reach-to-grasping movement and the grasping images analysis.

  2. Depth-cue integration in grasp programming: no evidence for a binocular specialism.

    Science.gov (United States)

    Keefe, Bruce D; Hibbard, Paul B; Watt, Simon J

    2011-04-01

    When we grasp with one eye covered, the finger and thumb are typically opened wider than for binocularly guided grasps, as if to build a margin-for-error into the movement. Also, patients with visual form agnosia can have profound deficits in their (otherwise relatively normal) grasping when binocular information is removed. One interpretation of these findings is that there is a functional specialism for binocular vision in the control of grasping. Alternatively, cue-integration theory suggests that binocular and monocular depth cues are combined in the control of grasping, and so impaired performance reflects not the loss of 'critical' binocular cues, but increased uncertainty per se. Unfortunately, removing binocular information confounds removing particular (binocular) depth cues with an overall reduction in the available information, and so such experiments cannot distinguish between these alternatives. We measured the effects on visually open-loop grasping of selectively removing monocular (texture) or binocular depth cues. To allow meaningful comparisons, we made psychophysical measurements of the uncertainty in size estimates in each case, so that the informativeness of binocular and monocular cues was known in each condition. Consistent with cue-integration theory, removing either binocular or monocular cues resulted in similar increases in grip apertures. In a separate experiment, we also confirmed that changes in uncertainty per se (keeping the same depth cues available) resulted in larger grip apertures. Overall, changes in the margin-for-error in grasping movements were determined by the uncertainty in size estimates and not by the presence or absence of particular depth cues. Our data therefore argue against a binocular specialism for grasp programming. Instead, grip apertures were smaller when binocular and monocular cues were available than with either cue alone, providing strong evidence that the visuo-motor system exploits the redundancy available

  3. Performance of FRCM strengthened beams subject to fatigue.

    Science.gov (United States)

    2017-05-31

    Fabric Reinforced Cementitious Matrix (FRCM) systems have been developed to strengthen or rehabilitate existing concrete and masonry structures subject to damage, steel reinforcement corrosion or requiring resistance capacity improvements due to incr...

  4. Monocular-Based 6-Degree of Freedom Pose Estimation Technology for Robotic Intelligent Grasping Systems

    Directory of Open Access Journals (Sweden)

    Tao Liu

    2017-02-01

    Full Text Available Industrial robots are expected to undertake ever more advanced tasks in the modern manufacturing industry, such as intelligent grasping, in which robots should be capable of recognizing the position and orientation of a part before grasping it. In this paper, a monocular-based 6-degree of freedom (DOF pose estimation technology to enable robots to grasp large-size parts at informal poses is proposed. A camera was mounted on the robot end-flange and oriented to measure several featured points on the part before the robot moved to grasp it. In order to estimate the part pose, a nonlinear optimization model based on the camera object space collinearity error in different poses is established, and the initial iteration value is estimated with the differential transformation. Measuring poses of the camera are optimized based on uncertainty analysis. Also, the principle of the robotic intelligent grasping system was developed, with which the robot could adjust its pose to grasp the part. In experimental tests, the part poses estimated with the method described in this paper were compared with those produced by a laser tracker, and results show the RMS angle and position error are about 0.0228° and 0.4603 mm. Robotic intelligent grasping tests were also successfully performed in the experiments.

  5. Monocular-Based 6-Degree of Freedom Pose Estimation Technology for Robotic Intelligent Grasping Systems.

    Science.gov (United States)

    Liu, Tao; Guo, Yin; Yang, Shourui; Yin, Shibin; Zhu, Jigui

    2017-02-14

    Industrial robots are expected to undertake ever more advanced tasks in the modern manufacturing industry, such as intelligent grasping, in which robots should be capable of recognizing the position and orientation of a part before grasping it. In this paper, a monocular-based 6-degree of freedom (DOF) pose estimation technology to enable robots to grasp large-size parts at informal poses is proposed. A camera was mounted on the robot end-flange and oriented to measure several featured points on the part before the robot moved to grasp it. In order to estimate the part pose, a nonlinear optimization model based on the camera object space collinearity error in different poses is established, and the initial iteration value is estimated with the differential transformation. Measuring poses of the camera are optimized based on uncertainty analysis. Also, the principle of the robotic intelligent grasping system was developed, with which the robot could adjust its pose to grasp the part. In experimental tests, the part poses estimated with the method described in this paper were compared with those produced by a laser tracker, and results show the RMS angle and position error are about 0.0228° and 0.4603 mm. Robotic intelligent grasping tests were also successfully performed in the experiments.

  6. Classification of Hand Grasp Kinetics and Types Using Movement-Related Cortical Potentials and EEG Rhythms

    Directory of Open Access Journals (Sweden)

    Mads Jochumsen

    2017-01-01

    Full Text Available Detection of single-trial movement intentions from EEG is paramount for brain-computer interfacing in neurorehabilitation. These movement intentions contain task-related information and if this is decoded, the neurorehabilitation could potentially be optimized. The aim of this study was to classify single-trial movement intentions associated with two levels of force and speed and three different grasp types using EEG rhythms and components of the movement-related cortical potential (MRCP as features. The feature importance was used to estimate encoding of discriminative information. Two data sets were used. 29 healthy subjects executed and imagined different hand movements, while EEG was recorded over the contralateral sensorimotor cortex. The following features were extracted: delta, theta, mu/alpha, beta, and gamma rhythms, readiness potential, negative slope, and motor potential of the MRCP. Sequential forward selection was performed, and classification was performed using linear discriminant analysis and support vector machines. Limited classification accuracies were obtained from the EEG rhythms and MRCP-components: 0.48±0.05 (grasp types, 0.41±0.07 (kinetic profiles, motor execution, and 0.39±0.08 (kinetic profiles, motor imagination. Delta activity contributed the most but all features provided discriminative information. These findings suggest that information from the entire EEG spectrum is needed to discriminate between task-related parameters from single-trial movement intentions.

  7. Grasp specific and user friendly interface design for myoelectric hand prostheses.

    Science.gov (United States)

    Mohammadi, Alireza; Lavranos, Jim; Howe, Rob; Choong, Peter; Oetomo, Denny

    2017-07-01

    This paper presents the design and characterisation of a hand prosthesis and its user interface, focusing on performing the most commonly used grasps in activities of daily living (ADLs). Since the operation of a multi-articulated powered hand prosthesis is difficult to learn and master, there is a significant rate of abandonment by amputees in preference for simpler devices. In choosing so, amputees chose to live with fewer features in their prosthesis that would more reliably perform the basic operations. In this paper, we look simultaneously at a hand prosthesis design method that aims for a small number of grasps, a low complexity user interface and an alternative method to the current use of EMG as a preshape selection method through the use of a simple button; to enable amputees to get to and execute the intended hand movements intuitively, quickly and reliably. An experiment is reported at the end of the paper comparing the speed and accuracy with which able-bodied naive subjects are able to select the intended preshapes through the use of a simplified EMG method and a simple button. It is shown that the button was significantly superior in the speed of successful task completion and marginally superior in accuracy (success of first attempt).

  8. The impact of subjectivity in performance evaluation practices on public sector managers' motivation

    NARCIS (Netherlands)

    van Rinsum, M.; Verbeeten, F.H.M.

    2012-01-01

    We conduct an explorative study to investigate the effect of subjectivity in performance evaluation practices on managerial motivation in public sector organisations. Increased subjectivity can enhance motivation if supervisors are able to provide better informational feedback. However, subjectivity

  9. Monkey hand postural synergies during reach-to-grasp in the absence of vision of the hand and object.

    Science.gov (United States)

    Mason, Carolyn R; Theverapperuma, Lalin S; Hendrix, Claudia M; Ebner, Timothy J

    2004-06-01

    Understanding how the CNS controls reach-to-grasp will require behavioral and neurophysiological studies of reach-to-grasp in the monkey, including the evaluation of whole-hand grasp with explicit force requirements. In this study, monkeys performed a reach-to-grasp task in which the size, shape, and orientation of the objects were varied. The monkeys were required to grasp each object at five force levels based on visual feedback. Seventeen positions on the wrist and hand were monitored to quantify kinematics. Hand shaping began with initiation of reach and continued throughout the reach, matching object properties even without vision of the hand or object. Grasp aperture scaled to object size. Singular value decomposition analysis of the marker positions identified two dominant hand postures. The first eigenvector or "eigenposture" consisted of an open hand configuration midway between flexion and extension that explained >93% of the variance. The second eigenposture consisted of hyperextension of all joints that accounted for another 4-5% of the variance. The two eigenpostures were similar across force levels and between monkeys. Reach kinematics consisted of a U-shaped hand path with a bell-shaped velocity profile. Trajectory and speed were independent of grasp force and object properties. In summary, hand shaping during the reach occurred without vision of the hand or object, and hand kinematics were not dependent on grasp force. Furthermore, the reach was independent of grasp force and object properties. These observations imply that the kinematics of reach-to-grasp and grasp force are controlled independently. Similar to humans, monkeys may use a simplifying strategy to reduce the degrees of freedom of the hand during reach-to-grasp.

  10. Medial grasping sutures significantly improve load to failure of the rotator cuff suture bridge repair.

    Science.gov (United States)

    Awwad, George E; Eng, Kevin; Bain, Gregory I; McGuire, Duncan; Jones, Claire F

    2014-05-01

    The suture bridge (SB) transosseous-equivalent rotator cuff repair reduces re-tear rates compared with single-row or other double-row constructs. However, failure rates continue to be high, especially in large and massive tears. The aim of this study was to assess the biomechanical performance of a new SB repair with use of a medial grasping suture compared with the traditional SB repair. Seven matched pairs of sheep infraspinatus tendons were randomly assigned to either SB or suture bridge with grasping suture (SBGS) repair. Each construct was subjected to cyclic loading and then loaded until failure under displacement control in a materials testing machine. Footprint displacement, ultimate load to failure, and mode of failure were assessed. The rotator cuff footprint displacement was less during tensile loading with the addition of the medial grasping suture. The ultimate load to failure was significantly greater for the SBGS repair group than for the SB repair group (334.0 N vs 79.8 N). The mode of failure was the tendon pulling off the footprint in all cases (type 1 tear). There were no failures in which the tendon tore at the medial row of anchors, leaving part of the tendon still on the footprint (type 2 tear). The addition of a medial grasping suture significantly improved the ultimate load to failure and reduced the footprint displacement of the SB rotator cuff repair in a biomechanical model. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

  11. Subjective sleepiness and sleep quality in adolescents are related to objective and subjective measures of school performance

    OpenAIRE

    Annemarie eBoschloo; Lydia eKrabbendam; Sanne eDekker; Lee, Nikki C.; Renate ede Groot; Jelle eJolles

    2013-01-01

    This study investigated the relation between sleep and school performance in a large sample of 561 adolescents aged 11-18 years. Three subjective measures of sleep were used: sleepiness, sleep quality and sleep duration. They were compared to three measures of school performance: objective school grades, self-reported school performance, and parent-reported school performance. Sleepiness – ‘I feel sleepy during the first hours at school’ – appeared to predict both school grades and self-repor...

  12. What a successful grasp tells about the success chances of grasps in its vicinity

    DEFF Research Database (Denmark)

    Bodenhagen, Leon; Detry, Renaud; Piater, Justus

    2011-01-01

    . We then show that convergence is an important problem associated with the grasp density approach and we propose a measure for the convergence of the densities. In this context, we show that the use of the statistically grounded anisotropic kernels leads to a significantly faster convergence of grasp...

  13. Subjective sleepiness and sleep quality in adolescents are related to objective and subjective measures of school performance

    NARCIS (Netherlands)

    Boschloo, Annemarie; Krabbendam, Lydia; Dekker, Sanne; Lee, Nikki; De Groot, Renate; Jolles, Jelle

    2016-01-01

    This study investigated the relation between sleep and school performance in a large sample of 561 adolescents aged 11–18 years. Three subjective measures of sleep were used: sleepiness, sleep quality, and sleep duration. They were compared to three measures of school performance: objective school

  14. Subjective sleepiness and sleep quality in adolescents are related to objective and subjective measures of school performance

    NARCIS (Netherlands)

    Boschloo, Annemarie; Krabbendam, Lydia; Dekker, Sanne; Lee, Nikki; De Groot, Renate; Jolles, Jelle

    2018-01-01

    This study investigated the relation between sleep and school performance in a large sam- ple of 561 adolescents aged 11–18 years. Three subjective measures of sleep were used: sleepiness, sleep quality, and sleep duration. They were compared to three measures of school performance: objective school

  15. Subjective sleepiness and sleep quality in adolescents are related to objective and subjective measures of school performance

    NARCIS (Netherlands)

    Boschloo, A.; Krabbendam, L.; Dekker, S.; Lee, N.; Groot, R. de; Jolles, J.

    2013-01-01

    This study investigated the relation between sleep and school performance in a large sample of 561 adolescents aged 11-18 years. Three subjective measures of sleep were used: sleepiness, sleep quality, and sleep duration. They were compared to three measures of school performance: objective school

  16. GRASPs in Golgi Structure and Function

    Science.gov (United States)

    Zhang, Xiaoyan; Wang, Yanzhuang

    2016-01-01

    The Golgi apparatus is a central intracellular membrane organelle for trafficking and modification of proteins and lipids. Its basic structure is a stack of tightly aligned flat cisternae. In mammalian cells, dozens of stacks are concentrated in the pericentriolar region and laterally connected to form a ribbon. Despite extensive research in the last decades, how this unique structure is formed and why its formation is important for proper Golgi functioning remain largely unknown. The Golgi ReAssembly Stacking Proteins, GRASP65, and GRASP55, are so far the only proteins shown to function in Golgi stacking. They are peripheral membrane proteins on the cytoplasmic face of the Golgi cisternae that form trans-oligomers through their N-terminal GRASP domain, and thereby function as the “glue” to stick adjacent cisternae together into a stack and to link Golgi stacks into a ribbon. Depletion of GRASPs in cells disrupts the Golgi structure and results in accelerated protein trafficking and defective glycosylation. In this minireview we summarize our current knowledge on how GRASPs function in Golgi structure formation and discuss why Golgi structure formation is important for its function. PMID:26779480

  17. GRASPs in Golgi Structure and Function

    Directory of Open Access Journals (Sweden)

    Xiaoyan eZhang

    2016-01-01

    Full Text Available The Golgi apparatus is a central intracellular membrane organelle for trafficking and modification of proteins and lipids. Its basic structure is a stack of tightly aligned flat cisternae. In mammalian cells, dozens of stacks are concentrated in the pericentriolar region and laterally connected to form a ribbon. Despite extensive research in the last decades, how this unique structure is formed and why its formation is important for proper Golgi functioning remain largely unknown. The Golgi ReAssembly Stacking Proteins, GRASP65 and GRASP55, are so far the only proteins shown to function in Golgi stacking. They are peripheral membrane proteins on the cytoplasmic face of the Golgi cisternae that form trans-oligomers through their N-terminal GRASP domain, and thereby function as the glue to stick adjacent cisternae together into a stack and to link Golgi stacks into a ribbon. Depletion of GRASPs in cells disrupts the Golgi structure and results in accelerated protein trafficking and defective glycosylation. In this minireview we summarize our current knowledge on how GRASPs function in Golgi structure formation and discuss why Golgi structure formation is important for its function.

  18. The visual neuroscience of robotic grasping achieving sensorimotor skills through dorsal-ventral stream integration

    CERN Document Server

    Chinellato, Eris

    2016-01-01

    This book presents interdisciplinary research that pursues the mutual enrichment of neuroscience and robotics. Building on experimental work, and on the wealth of literature regarding the two cortical pathways of visual processing - the dorsal and ventral streams - we define and implement, computationally and on a real robot, a functional model of the brain areas involved in vision-based grasping actions. Grasping in robotics is largely an unsolved problem, and we show how the bio-inspired approach is successful in dealing with some fundamental issues of the task. Our robotic system can safely perform grasping actions on different unmodeled objects, denoting especially reliable visual and visuomotor skills. The computational model and the robotic experiments help in validating theories on the mechanisms employed by the brain areas more directly involved in grasping actions. This book offers new insights and research hypotheses regarding such mechanisms, especially for what concerns the interaction between the...

  19. Development of autonomous grasping and navigating robot

    Science.gov (United States)

    Kudoh, Hiroyuki; Fujimoto, Keisuke; Nakayama, Yasuichi

    2015-01-01

    The ability to find and grasp target items in an unknown environment is important for working robots. We developed an autonomous navigating and grasping robot. The operations are locating a requested item, moving to where the item is placed, finding the item on a shelf or table, and picking the item up from the shelf or the table. To achieve these operations, we designed the robot with three functions: an autonomous navigating function that generates a map and a route in an unknown environment, an item position recognizing function, and a grasping function. We tested this robot in an unknown environment. It achieved a series of operations: moving to a destination, recognizing the positions of items on a shelf, picking up an item, placing it on a cart with its hand, and returning to the starting location. The results of this experiment show the applicability of reducing the workforce with robots.

  20. Human Grasp Assist Device With Exoskeleton

    Science.gov (United States)

    Bergelin, Bryan J (Inventor); Ihrke, Chris A. (Inventor); Davis, Donald R. (Inventor); Linn, Douglas Martin (Inventor); Bridgwater, Lyndon B. J. (Inventor)

    2014-01-01

    A grasp assist system includes a glove, actuator assembly, and controller. The glove includes a digit, i.e., a finger or thumb, and a force sensor. The sensor measures a grasping force applied to an object by an operator wearing the glove. Phalange rings are positioned with respect to the digit. A flexible tendon is connected at one end to one of the rings and is routed through the remaining rings. An exoskeleton positioned with respect to the digit includes hinged interconnecting members each connected to a corresponding ring, and/or a single piece of slotted material. The actuator assembly is connected to another end of the tendon. The controller calculates a tensile force in response to the measured grasping force, and commands the tensile force from the actuator assembly to thereby pull on the tendon. The exoskeleton offloads some of the tensile force from the operator's finger to the glove.

  1. Getting the right grasp on executive function

    Directory of Open Access Journals (Sweden)

    Claudia L R Gonzalez

    2014-04-01

    Full Text Available Executive Function (EF refers to important socio-emotional and cognitive skills that are known to be highly correlated with both academic and life success. EF is a blanket term that is considered to include self-regulation, working memory, and planning. Recent studies have shown a relationship between EF and motor control. The emergence of motor control coincides with that of EF, hence understanding the relationship between these two domains could have significant implications for early detection and remediation of later EF deficits. The purpose of the current study was to investigate this relationship in young children. This study incorporated the Behavioural Rating Inventory of Executive Function (BRIEF and two motor assessments with a focus on precision grasping to test this hypothesis. The BRIEF is comprised of two indices of EF: 1 the Behavioral Regulation Index (BRI containing three subscales: Inhibit, Shift, and Emotional Control; 2 the Metacognition Index (MI containing five subscales: Initiate, Working Memory, Plan/Organize, Organization of Materials, and Monitor. A global executive composite (GEC is derived from the two indices. In this study, right-handed children aged 5-6 and 9-10 were asked to: grasp-to-construct (Lego® models; and grasp-to-place (wooden blocks, while their parents completed the BRIEF questionnaire. Analysis of results indicated significant correlations between the strength of right hand preference for grasping and numerous elements of the BRIEF including the BRI, MI, and GEC. Specifically, the more the right hand was used for grasping the better the EF ratings. In addition, patterns of space-use correlated with the GEC in several subscales of the BRIEF. Finally and remarkably, the results also showed a reciprocal relationship between hand and space use for grasping and EF. These findings are discussed with respect to: 1 the developmental overlap of motor and executive functions; 2 detection of EF deficits through

  2. Performativity / Expressivity: The Mobile Micro Screen and Its Subject.

    NARCIS (Netherlands)

    Verhoeff, N.|info:eu-repo/dai/nl/241603471

    2014-01-01

    Informed by a tradition of cinema and visual culture studies on the one hand, and science and technology studies and new materialism on the other, we mobilize Peircean semiotics in order to theorize new media technologies and related practices. Our question is, in what way performativity and

  3. Real-time vision, tactile cues, and visual form agnosia: removing haptic feedback from a "natural" grasping task induces pantomime-like grasps.

    Science.gov (United States)

    Whitwell, Robert L; Ganel, Tzvi; Byrne, Caitlin M; Goodale, Melvyn A

    2015-01-01

    Investigators study the kinematics of grasping movements (prehension) under a variety of conditions to probe visuomotor function in normal and brain-damaged individuals. "Natural" prehensile acts are directed at the goal object and are executed using real-time vision. Typically, they also entail the use of tactile, proprioceptive, and kinesthetic sources of haptic feedback about the object ("haptics-based object information") once contact with the object has been made. Natural and simulated (pantomimed) forms of prehension are thought to recruit different cortical structures: patient DF, who has visual form agnosia following bilateral damage to her temporal-occipital cortex, loses her ability to scale her grasp aperture to the size of targets ("grip scaling") when her prehensile movements are based on a memory of a target previewed 2 s before the cue to respond or when her grasps are directed towards a visible virtual target but she is denied haptics-based information about the target. In the first of two experiments, we show that when DF performs real-time pantomimed grasps towards a 7.5 cm displaced imagined copy of a visible object such that her fingers make contact with the surface of the table, her grip scaling is in fact quite normal. This finding suggests that real-time vision and terminal tactile feedback are sufficient to preserve DF's grip scaling slopes. In the second experiment, we examined an "unnatural" grasping task variant in which a tangible target (along with any proxy such as the surface of the table) is denied (i.e., no terminal tactile feedback). To do this, we used a mirror-apparatus to present virtual targets with and without a spatially coincident copy for the participants to grasp. We compared the grasp kinematics from trials with and without terminal tactile feedback to a real-time-pantomimed grasping task (one without tactile feedback) in which participants visualized a copy of the visible target as instructed in our laboratory in the

  4. Real-time vision, tactile cues, and visual form agnosia: removing haptic feedback from a “natural” grasping task induces pantomime-like grasps

    Science.gov (United States)

    Whitwell, Robert L.; Ganel, Tzvi; Byrne, Caitlin M.; Goodale, Melvyn A.

    2015-01-01

    Investigators study the kinematics of grasping movements (prehension) under a variety of conditions to probe visuomotor function in normal and brain-damaged individuals. “Natural” prehensile acts are directed at the goal object and are executed using real-time vision. Typically, they also entail the use of tactile, proprioceptive, and kinesthetic sources of haptic feedback about the object (“haptics-based object information”) once contact with the object has been made. Natural and simulated (pantomimed) forms of prehension are thought to recruit different cortical structures: patient DF, who has visual form agnosia following bilateral damage to her temporal-occipital cortex, loses her ability to scale her grasp aperture to the size of targets (“grip scaling”) when her prehensile movements are based on a memory of a target previewed 2 s before the cue to respond or when her grasps are directed towards a visible virtual target but she is denied haptics-based information about the target. In the first of two experiments, we show that when DF performs real-time pantomimed grasps towards a 7.5 cm displaced imagined copy of a visible object such that her fingers make contact with the surface of the table, her grip scaling is in fact quite normal. This finding suggests that real-time vision and terminal tactile feedback are sufficient to preserve DF’s grip scaling slopes. In the second experiment, we examined an “unnatural” grasping task variant in which a tangible target (along with any proxy such as the surface of the table) is denied (i.e., no terminal tactile feedback). To do this, we used a mirror-apparatus to present virtual targets with and without a spatially coincident copy for the participants to grasp. We compared the grasp kinematics from trials with and without terminal tactile feedback to a real-time-pantomimed grasping task (one without tactile feedback) in which participants visualized a copy of the visible target as instructed in our

  5. Planning reaching and grasping movements: the problem of obstacle avoidance.

    Science.gov (United States)

    Vaughan, J; Rosenbaum, D A; Meulenbroek, R G

    2001-04-01

    In this article, we review a model of the movement-planning processes that people use for direct reaching, reaching around obstacles, and grasping, and we present observations of subjects' repeated movements of the hand to touch 2 target locations, circumventing an intervening obstacle. The model defines an obstacle as a posture that, if adopted, would intersect with any part of the environment (including the actor himself or herself). The model finds a trajectory that is likely to bring the end-effector to the target by means of a one-or two- stage planning process. Each stage exploits the principles of instance retrieval and instance generation. In the first stage, a goal posture is identified, and the trajectory of a direct transition to that posture is tested for collision. If the direct movement has no collision, the movement to the target is immediately executed in joint space. If, however, the direct movement is foreseen to result in a collision, a second planning stage is invoked. The second planing stage identifies a via posture, movement through which will probably avoid the collision. Movement to and from the via posture is then superimposed on the main movement to the target so that the combined movement reaches the target without colliding with intervening obstacles. We describe the details of instance retrieval and instance generation for each of these planning stages and compare the model's performance with the observed kinematics of direct movements as well as movements around an obstacle. Then we suggest how the model might contribute to the study of movements in people with motor disorders such as spastic hemiparesis.

  6. Subjective Sleepiness and Sleep Quality in Adolescents are Related to Objective and Subjective Measures of School Performance

    OpenAIRE

    Boschloo, Annemarie; Krabbendam, Lydia; Dekker, Sanne; Lee, Nikki; De Groot, Renate; Jolles, Jelle

    2013-01-01

    This study investigated the relation between sleep and school performance in a large sample of 561 adolescents aged 11–18 years. Three subjective measures of sleep were used: sleepiness, sleep quality, and sleep duration. They were compared to three measures of school performance: objective school grades, self-reported school performance, and parent-reported school performance. Sleepiness – “I feel sleepy during the first hours at school” – appeared to predict both school grades and self-repo...

  7. Interactions of task and subject variables among continuous performance tests.

    Science.gov (United States)

    Denney, Colin B; Rapport, Mark D; Chung, Kyong-Mee

    2005-04-01

    Contemporary models of working memory suggest that target paradigm (TP) and target density (TD) should interact as influences on error rates derived from continuous performance tests (CPTs). The present study evaluated this hypothesis empirically in a typically developing, ethnically diverse sample of children. The extent to which scores based on different combinations of these task parameters showed different patterns of relationship to age, intelligence, and gender was also assessed. Four continuous performance tests were derived by combining two target paradigms (AX and repeated letter target stimuli) with two levels of target density (8.3% and 33%). Variations in mean omission (OE) and commission (CE) error rates were examined within and across combinations of TP and TD. In addition, a nested series of structural equation models was utilized to examine patterns of relationship among error rates, age, intelligence, and gender. Target paradigm and target density interacted as influences on error rates. Increasing density resulted in higher OE and CE rates for the AX paradigm. In contrast, the high density condition yielded a decline in OE rates accompanied by a small increase in CEs using the repeated letter CPT. Target paradigms were also distinguishable on the basis of age when using OEs as the performance measure, whereas combinations of age and intelligence distinguished between density levels but not target paradigms using CEs as the dependent measure. Different combinations of target paradigm and target density appear to yield scores that are conceptually and psychometrically distinguishable. Consequently, developmentally appropriate interpretation of error rates across tasks may require (a) careful analysis of working memory and attentional resources required for successful performance, and (b) normative data bases that are differently stratified with respect to combinations of age and intelligence.

  8. The force synergy of human digits in static and dynamic cylindrical grasps.

    Directory of Open Access Journals (Sweden)

    Li-Chieh Kuo

    Full Text Available This study explores the force synergy of human digits in both static and dynamic cylindrical grasping conditions. The patterns of digit force distribution, error compensation, and the relationships among digit forces are examined to quantify the synergetic patterns and coordination of multi-finger movements. This study recruited 24 healthy participants to perform cylindrical grasps using a glass simulator under normal grasping and one-finger restricted conditions. Parameters such as the grasping force, patterns of digit force distribution, and the force coefficient of variation are determined. Correlation coefficients and principal component analysis (PCA are used to estimate the synergy strength under the dynamic grasping condition. Specific distribution patterns of digit forces are identified for various conditions. The compensation of adjacent fingers for the force in the normal direction of an absent finger agrees with the principle of error compensation. For digit forces in anti-gravity directions, the distribution patterns vary significantly by participant. The forces exerted by the thumb are closely related to those exerted by other fingers under all conditions. The index-middle and middle-ring finger pairs demonstrate a significant relationship. The PCA results show that the normal forces of digits are highly coordinated. This study reveals that normal force synergy exists under both static and dynamic cylindrical grasping conditions.

  9. Grasp planning for a reconfigurable parallel robot with an underactuated arm structure

    Directory of Open Access Journals (Sweden)

    M. Riedel

    2010-12-01

    Full Text Available In this paper, a novel approach of grasp planning is applied to find out the appropriate grasp points for a reconfigurable parallel robot called PARAGRIP (Parallel Gripping. This new handling system is able to manipulate objects in the six-dimensional Cartesian space by several robotic arms using only six actuated joints. After grasping, the contact elements at the end of the underactuated arm mechanisms are connected to the object which forms a closed loop mechanism similar to the architecture of parallel manipulators. As the mounting and grasp points of the arms can easily be changed, the manipulator can be reconfigured to match the user's preferences and needs. This paper raises the question, how and where these grasp points are to be placed on the object to perform well for a certain manipulation task.

    This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010, 19 August 2010, Montréal, Canada.

  10. Action is immune to the effects of Weber's law throughout the entire grasping trajectory.

    Science.gov (United States)

    Ganel, Tzvi; Freud, Erez; Meiran, Nachshon

    2014-06-24

    Vision for action and vision for perception have been suggested to be mediated by overlapping yet dissociable mechanisms. Recent evidence provided basic psychophysical support for this suggestion. In particular, it has been shown that Weber's law, the decrease in visual resolution with object size, does not affect the maximum grip aperture (MGA) between the fingers prior to grasp. Several studies replicated this result, but have argued that grasping may still obey Weber's law at early movement stages. Here, we show that this apparent adherence to Weber's law was confounded by task demands. Specifically, subjects were asked to keep their fingers closed prior to grasp, which encouraged them to open their fingers faster for larger compared to smaller objects. In two experiments, we tested this proposal by disentangling the effects of velocity from those of Weber's law. In Experiment 1, subjects were asked to keep their fingers open wide-apart prior to grasp, which encouraged them to close their fingers faster, rather than slower, to smaller objects. Now, the apparent adherence to Weber's law was reversed, and higher resolution was found for larger compared to smaller objects, thus indicating a "reversed" Weber's law. In Experiment 2, we manipulated task demands to equate aperture velocities across different objects sizes. When velocity was equated, no effects of Weber's law were found throughout the movement. These findings show that previous studies have confounded visual resolution with fingers' velocity, which led to an erroneous conclusion that Weber's law affected grasping at early stages of the movement. © 2014 ARVO.

  11. How to grasp a ripe tomato

    NARCIS (Netherlands)

    Verhagen, L.

    2012-01-01

    Fortunately, we don’t have to think about this when we are standing in the supermarket after a busy day. We adjust our grip without effort, making sure we don’t squish an overripe tomato, while we firmly grasp a hard green one. This is actually a complex task in which humans are surprisingly

  12. Foot-targeting in reaching and grasping

    NARCIS (Netherlands)

    Sparrow, W.A.; van der Kamp, J.; Savelsbergh, G.J.P.; Tirosh, O.

    2003-01-01

    Foot positioning was investigated when right-handed (Experiment One) and left handed adults (Experiment Two) stopped walking to grasp a stationary 70 mm ball at shoulder height. In both experiments centroid location formed by the toe and heel coordinates relative to the object was highly consistent

  13. Grasp Algorithms For Optotactile Robotic Sample Acquisition Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Robotic sample acquisition is essentially grasping. Multi-finger robot sample grasping devices are controlled to securely pick up samples. Equations have been...

  14. Homography-based grasp tracking for planar objects

    NARCIS (Netherlands)

    Carloni, Raffaella; Recatala, Gabriel; Melchiorri, Claudio; Sanz, Pedro J.; Cervera, Enric

    The visual tracking of grasp points is an essential operation for the execution of an approaching movement of a robot arm to an object: the grasp points are used as features for the definition of the control law. This work describes a strategy for tracking grasps on planar objects based on the use

  15. On transferability and contexts when using simulated grasp databases

    DEFF Research Database (Denmark)

    Jørgensen, Jimmy Alison; Ellekilde, Lars-Peter; Kraft, Dirk

    2015-01-01

    It has become a common practice to use simulation to generate large databases of good grasps for grasp planning in robotics research. However, the existence of a generic simulation context that enables the generation of high quality grasps that can be used in several different contexts such as bi...

  16. The psychophysics of workload - A second look at the relationship between subjective measures and performance

    Science.gov (United States)

    Gopher, D.; Chillag, N.; Arzi, N.

    1985-01-01

    Load estimates based upon subjective and performance indices were compared for subjects performing size matching and letter typing tasks under 6 levels of priorities, in single and dual task conditions. Each half of the group used a different task as reference in their subjective judgement. The results are interpreted to indicate that subjective measures are especially sensitive to voluntary allocation of attention and to the load on working memory. Association with performance is expected whenever these two factors are main determinants of performance efficiency, otherwise the two are likely to dissociate.

  17. Subjective sleepiness and sleep quality in adolescents are related to objective and subjective measures of school performance

    Directory of Open Access Journals (Sweden)

    Annemarie eBoschloo

    2013-02-01

    Full Text Available This study investigated the relation between sleep and school performance in a large sample of 561 adolescents aged 11-18 years. Three subjective measures of sleep were used: sleepiness, sleep quality and sleep duration. They were compared to three measures of school performance: objective school grades, self-reported school performance, and parent-reported school performance. Sleepiness – ‘I feel sleepy during the first hours at school’ – appeared to predict both school grades and self-reported school performance. Sleep quality on the other hand – as a measure of (uninterrupted sleep and/or problems falling asleep or waking up – predicted parent-reported school performance. Self- and parent-reported school performance correlated only moderately with school grades. So it turns out that the measures used to measure either sleep or school performance impacts whether or not a relation is found. Further research on sleep and school performance should take this into account. The findings do underscore the notion that sleep in adolescence can be important for learning. They are compatible with the hypothesis that a reduced sleep quality can give rise to sleepiness in the first hours at school which results in lower school performance. This notion could have applied value in counseling adolescents and their parents in changing adolescents’ sleep behavior.

  18. Subjective Sleepiness and Sleep Quality in Adolescents are Related to Objective and Subjective Measures of School Performance.

    Science.gov (United States)

    Boschloo, Annemarie; Krabbendam, Lydia; Dekker, Sanne; Lee, Nikki; de Groot, Renate; Jolles, Jelle

    2013-01-01

    This study investigated the relation between sleep and school performance in a large sample of 561 adolescents aged 11-18 years. Three subjective measures of sleep were used: sleepiness, sleep quality, and sleep duration. They were compared to three measures of school performance: objective school grades, self-reported school performance, and parent-reported school performance. Sleepiness - "I feel sleepy during the first hours at school" - appeared to predict both school grades and self-reported school performance. Sleep quality on the other hand - as a measure of (un)interrupted sleep and/or problems falling asleep or waking up - predicted parent-reported school performance. Self- and parent-reported school performance correlated only moderately with school grades. So it turns out that the measures used to measure either sleep or school performance impacts whether or not a relation is found. Further research on sleep and school performance should take this into account. The findings do underscore the notion that sleep in adolescence can be important for learning. They are compatible with the hypothesis that a reduced sleep quality can give rise to sleepiness in the first hours at school which results in lower school performance. This notion could have applied value in counseling adolescents and their parents in changing adolescents' sleep behavior.

  19. Improved grasp force sensitivity for prosthetic hands through force-derivative feedback.

    Science.gov (United States)

    Engeberg, Erik D; Meek, Sanford

    2008-02-01

    Sensitivity of applied grasp force is improved for a myoelectrically controlled prosthetic hand under force control through normal force-derivative feedback. Benchtop experiments and results from 12 human test subjects indicate that normal force-derivative feedback can be used in prosthetic hands to help prevent accidental damage to delicate objects.

  20. Continuous grasp algorithm applied to economic dispatch problem of thermal units

    Energy Technology Data Exchange (ETDEWEB)

    Vianna Neto, Julio Xavier [Pontifical Catholic University of Parana - PUCPR, Curitiba, PR (Brazil). Undergraduate Program at Mechatronics Engineering; Bernert, Diego Luis de Andrade; Coelho, Leandro dos Santos [Pontifical Catholic University of Parana - PUCPR, Curitiba, PR (Brazil). Industrial and Systems Engineering Graduate Program, LAS/PPGEPS], e-mail: leandro.coelho@pucpr.br

    2010-07-01

    The economic dispatch problem (EDP) is one of the fundamental issues in power systems to obtain benefits with the stability, reliability and security. Its objective is to allocate the power demand among committed generators in the most economical manner, while all physical and operational constraints are satisfied. The cost of power generation, particularly in fossil fuel plants, is very high and economic dispatch helps in saving a significant amount of revenue. Recently, as an alternative to the conventional mathematical approaches, modern heuristic optimization techniques such as simulated annealing, evolutionary algorithms, neural networks, ant colony, and tabu search have been given much attention by many researchers due to their ability to find an almost global optimal solution in EDPs. On other hand, continuous GRASP (C-GRASP) is a stochastic local search meta-heuristic for finding cost-efficient solutions to continuous global optimization problems subject to box constraints. Like a greedy randomized adaptive search procedure (GRASP), a C-GRASP is a multi-start procedure where a starting solution for local improvement is constructed in a greedy randomized fashion. The C-GRASP algorithm is validated for a test system consisting of fifteen units, test system that takes into account spinning reserve and prohibited operating zones constrains. (author)

  1. The MICROSTAR electrostatic accelerometer for the GRASP Mission

    Science.gov (United States)

    Foulon, Bernard; Christophe, Bruno; Liorzou, Francoise; Huynh, Phuong-Anh; Perrot, Eddy

    2015-04-01

    The Geodetic Reference Antenna in Space (GRASP) is a micro satellite mission concept dedicated to the enhancement of all the space geodetic techniques, and promising revolutionary improvements to the definition of the Terrestrial Reference Frame (TRF). GRASP collocates GPS, SLR, VLBI, and DORIS sensors on a dedicated spacecraft in order to establish precise and stable ties between the key geodetic techniques used to define and disseminate the TRF. GRASP also offers a space-based reference antenna for the present and future Global Navigation Satellite Systems (GNSS). The integration of an ultra sensitive accelerometer at the Center of mass of the satellite can provide not only improvement of the Precise Orbit Determination (POD) by the accurate measurement of the non-gravitational force acting on the surface of the satellite but also by the possibility to calibrate with an accuracy better than 100 µm the change in the position of the Satellite Center of Mass as it is performed in the GRACE mission and to determine the precise motion of the antennas assuming some rigid structure between them and the accelerometer as it is done between the star sensor, the optical cube assembly of satellite laser ranging system and the accelerometer in the GRACE-Follow On mission. The proposed accelerometer is miniaturized version of the electrostatic accelerometers developed for the Earth gravity missions CHAMP, GRACE, GOCE and GRACE-FO. He has 3 sensitive axes thanks to a cubic proof-mass and provides the 3 linear accelerations and the 3 angular accelerations about its 3 orthogonal axes. He is called MICROSTAR and its foreseen performance is a linear acceleration noise lower than 10-11 ms-2/Hz1/2 into a measurement bandwidth between 10-3 Hz and 0.1 Hz.

  2. Grasping the Formless in Stones

    DEFF Research Database (Denmark)

    Aktor, Mikael

    2017-01-01

    Investigating the ritual and social aesthetics of "petromorphic gods" in a Hindu context, this chapter demonstrates that it is not a single theoretical key but rather the interpretive combination of theories which allows one to understand how stones connect religious knowledge, performative action...... objects in cognitive technologies, and the structure of the human mind, the chapter unravels how the sensory and synaesthetic qualities have made these stones ritually important. In this weaving together of different aspects, the chapter illustrates the way in which an aesthetic approach forms...... a connective pathway within religious studies scholarship....

  3. Grasping Unknown Objects in an Early Cognitive Vision System

    DEFF Research Database (Denmark)

    Popovic, Mila

    2011-01-01

    Grasping of unknown objects presents an important and challenging part of robot manipulation. The growing area of service robotics depends upon the ability of robots to autonomously grasp and manipulate a wide range of objects in everyday environments. Simple, non task-specific grasps of unknown...... presents a system for robotic grasping of unknown objects us- ing stereo vision. Grasps are defined based on contour and surface information provided by the Early Cognitive Vision System, that organizes visual informa- tion into a biologically motivated hierarchical representation. The contributions...

  4. Simulation results of the grasping analysis of an underactuated finger

    Directory of Open Access Journals (Sweden)

    Niola Vincenzo

    2016-01-01

    Full Text Available The results of a number of simulations concerning the grasping analysis is presented. The grasping device consist in an under-actuated finger driven by un-extendible tendon that is one of the fingers of a mechanical prosthesis that was principally conceived as human prosthesis. The results, however, are useful for any similar finger to be used in grasping devices for industrial and agricultural applications, Aanalysis maps of the grasping were obtained which show the “robustness” of the socket. The method seems to be a suitable tool for the optimum design of such under-actuated fingers for grasping devices.

  5. Tactile feedback is an effective instrument for the training of grasping with a prosthesis at low- and medium-force levels.

    Science.gov (United States)

    De Nunzio, Alessandro Marco; Dosen, Strahinja; Lemling, Sabrina; Markovic, Marko; Schweisfurth, Meike Annika; Ge, Nan; Graimann, Bernhard; Falla, Deborah; Farina, Dario

    2017-08-01

    Grasping is a complex task routinely performed in an anticipatory (feedforward) manner, where sensory feedback is responsible for learning and updating the internal model of grasp dynamics. This study aims at evaluating whether providing a proportional tactile force feedback during the myoelectric control of a prosthesis facilitates learning a stable internal model of the prosthesis force control. Ten able-bodied subjects controlled a sensorized myoelectric prosthesis performing four blocks of consecutive grasps at three levels of target force (30, 50, and 70%), repeatedly closing the fully opened hand. In the first and third block, the subjects received tactile and visual feedback, respectively, while during the second and fourth block, the feedback was removed. The subjects also performed an additional block with no feedback 1 day after the training (Retest). The median and interquartile range of the generated forces was computed to assess the accuracy and precision of force control. The results demonstrated that the feedback was indeed an effective instrument for the training of prosthesis control. After the training, the subjects were still able to accurately generate the desired force for the low and medium target (30 and 50% of maximum force available in a prosthesis), despite the feedback being removed within the session and during the retest (low target force). However, the training was substantially less successful for high forces (70% of prosthesis maximum force), where subjects exhibited a substantial loss of accuracy as soon as the feedback was removed. The precision of control decreased with higher forces and it was consistent across conditions, determined by an intrinsic variability of repeated myoelectric grasping. This study demonstrated that the subject could rely on the tactile feedback to adjust the motor command to the prosthesis across trials. The subjects adjusted the mean level of muscle activation (accuracy), whereas the precision could not

  6. The magic grasp: motor expertise in deception.

    Directory of Open Access Journals (Sweden)

    Cristiana Cavina-Pratesi

    Full Text Available BACKGROUND: Most of us are poor at faking actions. Kinematic studies have shown that when pretending to pick up imagined objects (pantomimed actions, we move and shape our hands quite differently from when grasping real ones. These differences between real and pantomimed actions have been linked to separate brain pathways specialized for different kinds of visuomotor guidance. Yet professional magicians regularly use pantomimed actions to deceive audiences. METHODOLOGY AND PRINCIPAL FINDINGS: In this study, we tested whether, despite their skill, magicians might still show kinematic differences between grasping actions made toward real versus imagined objects. We found that their pantomimed actions in fact closely resembled real grasps when the object was visible (but displaced (Experiment 1, but failed to do so when the object was absent (Experiment 2. CONCLUSIONS AND SIGNIFICANCE: We suggest that although the occipito-parietal visuomotor system in the dorsal stream is designed to guide goal-directed actions, prolonged practice may enable it to calibrate actions based on visual inputs displaced from the action.

  7. A multilevel approach to relating subjective workload to performance after shifts in task demand.

    Science.gov (United States)

    Mracek, Derek L; Arsenault, Matthew L; Day, Eric Anthony; Hardy, Jay H; Terry, Robert A

    2014-12-01

    The aim of this laboratory experiment was to demonstrate how taking a longitudinal, multilevel approach can be used to examine the dynamic relationship between subjective workload and performance over a given period of activity involving shifts in task demand. Subjective workload and conditions of the performance environment are oftentimes examined via cross-sectional designs without distinguishing within-from between-person effects. Given the dynamic nature of performance phenomena, multilevel designs coupled with manipulations of task demand shifts are needed to better model the dynamic relationships between state and trait components of subjective workload and performance. With a sample of 75 college students and a computer game representing a complex decision-making environment, increases and decreases in task demand were counterbalanced and subjective workload and performance were measured concurrently in regular intervals within performance episodes. Data were analyzed using hierarchical linear modeling. Both between- and especially within-person effects were dynamic. Nevertheless, at both levels of analysis, higher subjective workload reflected performance problems, especially more downstream from increases in task demand. As a function of cognitive-energetic processes, shifts in task demand are associated with changes in how subjective workload is related to performance over a given period of activity. Multilevel, longitudinal approaches are useful for distinguishing and examining the dynamic relationships between state and trait components of subjective workload and performance. The findings of this research help to improve the understanding of how a sequence of demands can exceed a performer's capability to respond to further demands.

  8. Evaluation of Human Prehension Using Grasp Quality Measures

    Directory of Open Access Journals (Sweden)

    Beatriz León

    2012-10-01

    Full Text Available One of the main features of the human hand is its grasping ability. Robot grasping has been studied for years and different quality measures have been proposed to evaluate the stability and manipulability of grasps. Although the human hand is obviously more complex than robot hands, the methods used in robotics might be adopted to study the human grasp. The purpose of this work is to propose a set of measures that allow the evaluation of different aspects of the human grasp. The most common robotic grasp quality measures have been adapted to the evaluation of the human hand and a new quality measure – the fatigue index – is proposed in order to incorporate the biomechanical aspect into the evaluation. The minimum set of indices that allows the evaluation of the different aspects of the grasp is obtained from the analysis of a human prehension experiment.

  9. Determinants of Girls' Performance in Science, Mathematics and Technology Subjects in Public Secondary Schools in Kenya

    Science.gov (United States)

    Musau, Lydia Mbaki; Migosi, Joash; Muola, James Matee

    2013-01-01

    There has been incessant low academic performance in Science, Mathematics and Technology (SMT) subjects especially among girls at form four level in Kitui Central District over the years. The aim of this study was to investigate the determinants of girls' performance in SMT subjects in public secondary schools. Using ex-post-facto survey research…

  10. GRASP to minimize total weighted tardiness in a permutation flow shop environment

    Directory of Open Access Journals (Sweden)

    Lina Paola Molina-Sánchez

    2016-01-01

    Full Text Available This paper addresses the scheduling problem in a Permutation Flow Shop (PFS environment, which is associated with many types of industries such as chemical, petrochemical, automobile manufacturing, metallurgical, textile, etc. Thus, this work intends to solve a PFS scheduling problem in order to minimize the total weighted tardiness, since it is an important sequencing criterion not only for on time delivery jobs but also for customer satisfaction. To solve the problem, GRASP (Greedy Randomized Adaptive Search Procedure metaheuristic is proposed as a solution, which has shown competitive results compared with other combinatorial problems. In addition, two utility functions called Weighted Modified Due Date (WMDD and Apparent Tardiness Cost (ATC are proposed to develop GRASP. These are based on dynamic dispatching rules and also known for solving the problem of total weighted tardiness for single machine scheduling problem. Next, an experimental design was carried out for comparing the GRASP performance with both utility functions and against the WEDD dispatching rule results. The results indicate that GRASP-WMDD could improve the total weighted tardiness in 47.8% compared with WEDD results. Finally, the GRASP-WMDD performance for the PFS total tardiness problem was evaluated, obtaining a relative deviation index of 13.89% and ranking the method over 26 heuristics and metaheuristics.

  11. Impact of glucose metabolism and birth size on cognitive performance in elderly subjects.

    Science.gov (United States)

    Paile-Hyvärinen, Maria; Räikkönen, Katri; Kajantie, Eero; Darby, David; Ylihärsilä, Hilkka; Salonen, Minna K; Osmond, Clive; Eriksson, Johan G

    2009-03-01

    We aimed to investigate the impact of diabetes and impaired glucose tolerance on cognitive performance and to explore the association between birth weight and cognitive performance among diabetic subjects. We performed a standard oral glucose tolerance test and a computerised test for assessment of cognitive performance (CogState) in 1243 subjects; 173 of them had type 2 diabetes. At the time of cognitive testing the mean age of the subjects was 64 years. Subjects with type 1 diabetes or a history of stroke were excluded. Subjects with known diabetes performed significantly poorer in cognitive tasks measuring visual attention, working memory and episodic learning than subjects with normal glucose tolerance. Subjects with newly diagnosed diabetes or milder impairments in glucose regulation did not differ from the normoglycaemic group. A low birth weight enhanced the association between diabetes and poor performance in the working memory and episodic learning tasks. Poorer cognitive performance was associated with known type 2 diabetes but not with newly diagnosed diabetes or milder impairments in glucose regulation. Low birth weight was found to be an additional vulnerability factor enhancing cognitive decline in diabetic subjects.

  12. Complex modulation of fingertip forces during precision grasp and lift after theta burst stimulation over the dorsal premotor cortex

    Directory of Open Access Journals (Sweden)

    Drljačić Dragana

    2017-01-01

    Full Text Available Background/Aim. Adaptive control and fingertip force synchronization of precise grasp stability during unimanual manipulation of small objects represents an illustrative example of highly fractionated movements that are foundation of fine motor control. It is assumed that this process is controlled by several motor areas of the frontal lobe, particularly applicable to the primary motor (M-1 and dorsal premotor cortex (PMd. Aiming to examine the role of PMd during fine coordination of fingertip forces we applied theta burst repetitive magnetic stimulation (TBS to disrupt neural processing in that cortical area. Methods. Using a single-blind, randomized, crossover design, 10 healthy subjects (29 ± 3.9 years received single sessions of continuous TBS (cTBS600, intermittent TBS (iTBS600, or sham stimulation, separate from one another at least one week, over the PMd region of dominant hemisphere. Precision grasp and lift were assessed by instrumented device, recording grip (G and load (L forces, during three manipulation tasks (ramp-and-hold, oscillation force producing and simple lifting tasks, with each hand separately, before and after interventions. Results. We observed the improvement of task performance related to constant error (CE in oscillation task with the dominant hand (DH after the iTBS (p = 0.009. On the contrary, the cTBS reduced variable error (VE for non-dominant hand (NH, p = 0.005. Considering force coordination we found that iTBS worsened variables for NH (G/L ratio, p = 0.017; cross-correlation of the G and L, p = 0.047; Gain, p = 0.047. Conclusion. These results demonstrate the ability of TBS to modulate fingertip forces during precision grasping and lifting, when applied over PMd. These findings support the role of PMd in human motor control and forces generation required to hold small objects stable in our hands.

  13. Active Grasping Control of Virtual-Dexterous-Robot Hand with Open Inventor

    Directory of Open Access Journals (Sweden)

    Jinbao Chen

    2014-01-01

    Full Text Available The grasping technology of the virtual-dexterous-robot (VDR hand plays a key role in the teleoperation of the space robot. For a grasp task in the virtual environment, the collision detection and virtual force calculation need to be implemented. Firstly, a tree-structure virtual scene including a VDR hand and a target object is built up with open inventor (OIV. Secondly, the collision manager provided by OIV is used for collision detection and the oriented bounding box (OBB is adopted to improve the real-time performance of collision detection. Thirdly, an algorithm is proposed for calculating the virtual force by using the contact deformation. And the contact deformation is calculated according to the transformation matrix between the coordinate systems of the two contact objects. Furthermore, the contact friction is also calculated by this matrix. Considering the virtual force, the modified stable grasping conditions are proposed which are suitable for the virtual grasping. Then a method is proposed for implementing the grasp or release operation by translating different nodes in the tree-structure scene, which can avoid destroying the tree structure. Finally, the viability and effectiveness of the proposed algorithms are proved by simulation experiments.

  14. Theta power decreases in preparation for voluntary isometric contractions performed with maximal subjective effort.

    Science.gov (United States)

    Weiss, T; Sust, M; Beyer, L; Hansen, E; Rost, R; Schmalz, T

    1995-07-07

    In order to find EEG parameters that can be attributed to movements performed with maximal subjective effort, EEG recordings and force measurements were realized in connection with isometric contractions (IMC). IMC were performed with submaximal and maximal subjective effort. Mean spectral power density within the theta band was found as an indicator for maximal subjective effort. The theta power across the parieto-occipital area decreases from rest through movements performed with submaximal force to movements performed with maximal effort. It is argued that this theta decrease possibly reflects a down-regulation of the posterior attention system in order to minimize the influences of external stimuli during the preparation for voluntary IMC performed with maximal subjective effort.

  15. Measuring organizational performance in the hospital industry: an exploratory comparison of objective and subjective methods.

    Science.gov (United States)

    McCracken, M J; McIlwain, T F; Fottler, M D

    2001-11-01

    One of the major challenges facing health services management researchers is the measurement of various aspects of organizational performance. This challenge is exacerbated by a reluctance of many healthcare organizations to share data with researchers because of a fear of competitor access to these data. Even where objective, reliable and valid measures of organizational performance are available, typically they are available only in aggregate form, rather than for individual organizations. In response to these constraints, researchers have used subjective measures of performance often based on the perception of key executives. This research compares the subjective perceptions of hospital executives to the objective financial performance data of 60 hospitals. While the correlations between the subjective and objective measures vary, return of assets (ROA) and operating margin are the most valid subjective financial measures of hospital performance. Implications for future research are discussed.

  16. Successful voluntary grasp and release using the cookie crusher myoelectric hand in 2-year-olds.

    Science.gov (United States)

    Meredith, J M; Uellendahl, J E; Keagy, R D

    1993-09-01

    We examined the ability of two 2-year-old children with limb deficiency to demonstrate grasp and release while using the cable-operated voluntary opening hook-hand and the externally powered single-site myoelectric Cookie Crusher system. The Cookie Crusher circuit is an electronic package that causes the prosthetic hand to open in response to muscle contraction and closes (as if crushing a cookie) when the muscle is relaxed. Both children were consistently good prosthetic wearers, beginning with their initial passive devices and progressing through their cable-operated hooks and hands. However, before they began to use the Cookie Crusher (Subject 1 at 25 months, Subject 2 at 30 months), neither had developed voluntary grasp or release in spite of 3 to 12 months' use of cable-operated voluntary opening prehensors. Both children developed a voluntary grasp and release for the first time within minutes of starting to use the Cookie Crusher. The more adept of the two children, a girl with a traumatic above-elbow amputation, showed prehensile function with the Cookie Crusher during play. The spontaneous use of the Cookie Crusher may be related to the predominance of associated reactions in young children. As children play bimanually, associated movements of the nondominant extremity often occur and, in the case of children with limb deficiencies fitted with Cookie Crusher prehensors, these associated reactions result in successful grasp and release. We will continue to follow the choice of effective control schemes in these children as they mature.

  17. A Strategy for Grasping unknown Objects based on Co-Planarity and Colour Information

    DEFF Research Database (Denmark)

    Popovic, Mila; Kraft, Dirk; Bodenhagen, Leon

    2010-01-01

    In this work, we describe and evaluate a grasping mechanism that does not make use of any specific object prior knowledge. The mechanism makes use of second-order relations between visually extracted multi-modal 3D features provided by an early cognitive vision system. More specifically...... with a reasonable success rate in rather complex environments (i.e., cluttered scenes with multiple objects). Moreover, we have embedded the algorithm within a cognitive system that allows for autonomous exploration and learning in different contexts. First, the system is able to perform long action sequences which...... a gasping attempt). Such labelled data is then used for improving the initially hard-wired algorithm by learning. Moreover, the grasping behaviour has been used in a cognitive system to trigger higher level processes such as object learning and learning of object specific grasping....

  18. Multisession, noninvasive closed-loop neuroprosthetic control of grasping by upper limb amputees.

    Science.gov (United States)

    Agashe, H A; Paek, A Y; Contreras-Vidal, J L

    2016-01-01

    Upper limb amputation results in a severe reduction in the quality of life of affected individuals due to their inability to easily perform activities of daily living. Brain-machine interfaces (BMIs) that translate grasping intent from the brain's neural activity into prosthetic control may increase the level of natural control currently available in myoelectric prostheses. Current BMI techniques demonstrate accurate arm position and single degree-of-freedom grasp control but are invasive and require daily recalibration. In this study we tested if transradial amputees (A1 and A2) could control grasp preshaping in a prosthetic device using a noninvasive electroencephalography (EEG)-based closed-loop BMI system. Participants attempted to grasp presented objects by controlling two grasping synergies, in 12 sessions performed over 5 weeks. Prior to closed-loop control, the first six sessions included a decoder calibration phase using action observation by the participants; thereafter, the decoder was fixed to examine neuroprosthetic performance in the absence of decoder recalibration. Ability of participants to control the prosthetic was measured by the success rate of grasping; ie, the percentage of trials within a session in which presented objects were successfully grasped. Participant A1 maintained a steady success rate (63±3%) across sessions (significantly above chance [41±5%] for 11 sessions). Participant A2, who was under the influence of pharmacological treatment for depression, hormone imbalance, pain management (for phantom pain as well as shoulder joint inflammation), and drug dependence, achieved a success rate of 32±2% across sessions (significantly above chance [27±5%] in only two sessions). EEG signal quality was stable across sessions, but the decoders created during the first six sessions showed variation, indicating EEG features relevant to decoding at a smaller timescale (100ms) may not be stable. Overall, our results show that (a) an EEG

  19. GRASP agents: social first, intelligent later

    OpenAIRE

    Hofstede, G.J.

    2017-01-01

    This paper urges that if we wish to give social intelligence to our agents, it pays to look at how we acquired our social intelligence ourselves. We are born with drives and motives that are innate and deeply social. Next, as children we are socialized to acquire norms and values and to understand rituals large and small. These social elements are the core of our being. We capture them in the acronym GRASP: Groups, Rituals, Affiliation, Status, Power. As a consequence, economic rationality or...

  20. Forward lunge as a functional performance test in ACL deficient subjects: test-retest reliability

    DEFF Research Database (Denmark)

    Alkjaer, Tine; Henriksen, Marius; Dyhre-Poulsen, Poul

    2009-01-01

    The forward lunge movement may be used as a functional performance test of anterior cruciate ligament (ACL) deficient and reconstructed subjects. The purposes were 1) to determine the test-retest reliability of a forward lunge in healthy subjects and 2) to determine the required numbers...

  1. Subjective Performance Evaluations, Self-esteem, and Ego-threats in Principal-agent Relations

    DEFF Research Database (Denmark)

    Sebald, Alexander Christopher; Walzl, Markus

    find that agents sanction whenever the feedback of principals is below their subjective self-evaluations even if the agents' payoff is independent of the principals' feedback. Based on our experimental analysis we propose a principal-agent model with subjective performance evaluations that accommodates...

  2. Stress and Performance: Effects of Subjective Work Load and Time Urgency.

    Science.gov (United States)

    Friend, Kenneth E.

    1982-01-01

    Measured subjective work load, time urgency, and other stress/motivation variables for management personnel taking a demanding problem-solving exam. Data suggest increases in psychological stresses like subjectively high work load and time urgency uniformly impair performance across the whole range of these variables. (Author)

  3. A method to evaluate performance reliability of individual subjects in laboratory research applied to work settings.

    Science.gov (United States)

    1978-10-01

    This report presents a method that may be used to evaluate the reliability of performance of individual subjects, particularly in applied laboratory research. The method is based on analysis of variance of a tasks-by-subjects data matrix, with all sc...

  4. Optimization by GRASP greedy randomized adaptive search procedures

    CERN Document Server

    Resende, Mauricio G C

    2016-01-01

    This is the first book to cover GRASP (Greedy Randomized Adaptive Search Procedures), a metaheuristic that has enjoyed wide success in practice with a broad range of applications to real-world combinatorial optimization problems. The state-of-the-art coverage and carefully crafted pedagogical style lends this book highly accessible as an introductory text not only to GRASP, but also to combinatorial optimization, greedy algorithms, local search, and path-relinking, as well as to heuristics and metaheuristics, in general. The focus is on algorithmic and computational aspects of applied optimization with GRASP with emphasis given to the end-user, providing sufficient information on the broad spectrum of advances in applied optimization with GRASP. For the more advanced reader, chapters on hybridization with path-relinking and parallel and continuous GRASP present these topics in a clear and concise fashion. Additionally, the book offers a very complete annotated bibliography of GRASP and combinatorial optimizat...

  5. Bio-inspired grasp control in a robotic hand with massive sensorial input.

    Science.gov (United States)

    Ascari, Luca; Bertocchi, Ulisse; Corradi, Paolo; Laschi, Cecilia; Dario, Paolo

    2009-02-01

    The capability of grasping and lifting an object in a suitable, stable and controlled way is an outstanding feature for a robot, and thus far, one of the major problems to be solved in robotics. No robotic tools able to perform an advanced control of the grasp as, for instance, the human hand does, have been demonstrated to date. Due to its capital importance in science and in many applications, namely from biomedics to manufacturing, the issue has been matter of deep scientific investigations in both the field of neurophysiology and robotics. While the former is contributing with a profound understanding of the dynamics of real-time control of the slippage and grasp force in the human hand, the latter tries more and more to reproduce, or take inspiration by, the nature's approach, by means of hardware and software technology. On this regard, one of the major constraints robotics has to overcome is the real-time processing of a large amounts of data generated by the tactile sensors while grasping, which poses serious problems to the available computational power. In this paper a bio-inspired approach to tactile data processing has been followed in order to design and test a hardware-software robotic architecture that works on the parallel processing of a large amount of tactile sensing signals. The working principle of the architecture bases on the cellular nonlinear/neural network (CNN) paradigm, while using both hand shape and spatial-temporal features obtained from an array of microfabricated force sensors, in order to control the sensory-motor coordination of the robotic system. Prototypical grasping tasks were selected to measure the system performances applied to a computer-interfaced robotic hand. Successful grasps of several objects, completely unknown to the robot, e.g. soft and deformable objects like plastic bottles, soft balls, and Japanese tofu, have been demonstrated.

  6. Efficacy of an implanted neuroprosthesis for restoring hand grasp in tetraplegia: a multicenter study.

    Science.gov (United States)

    Peckham, P H; Keith, M W; Kilgore, K L; Grill, J H; Wuolle, K S; Thrope, G B; Gorman, P; Hobby, J; Mulcahey, M J; Carroll, S; Hentz, V R; Wiegner, A

    2001-10-01

    To evaluate an implanted neuroprosthesis that allows tetraplegic users to control grasp and release in 1 hand. Multicenter cohort trial with at least 3 years of follow-up. Function for each participant was compared before and after implantation, and with and without the neuroprosthesis activated. Tertiary spinal cord injury (SCI) care centers, 8 in the United States, 1 in the United Kingdom, and 1 in Australia. Fifty-one tetraplegic adults with C5 or C6 SCIs. An implanted neuroprosthetic system, in which electric stimulation of the grasping muscles of 1 arm are controlled by using contralateral shoulder movements, and concurrent tendon transfer surgery. Assessed participants' ability to grasp, move, and release standardized objects; degree of assistance required to perform activities of daily living (ADLs), device usage; and user satisfaction. Pinch force; grasp and release tests; ADL abilities test and ADL assessment test; and user satisfaction survey. Pinch force was significantly greater with the neuroprosthesis in all available 50 participants, and grasp-release abilities were improved in 49. All tested participants (49/49) were more independent in performing ADLs with the neuroprosthesis than they were without it. Home use of the device for regular function and exercise was reported by over 90% of the participants, and satisfaction with the neuroprosthesis was high. The grasping ability provided by the neuroprosthesis is substantial and lasting. The neuroprosthesis is safe, well accepted by users, and offers improved independence for a population without comparable alternatives. Copyright 2001 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

  7. Subjective user experience and performance with active tangibles on a tabletop interface

    NARCIS (Netherlands)

    Erp, J.B. van; Toet, A.; Meijer, K.; Janssen, J.; Jong, A. de

    2015-01-01

    We developed active tangibles (Sensators) that can be used in combination with multitouch tabletops and that can provide multisensory (visual, auditory, and vibrotactile) feedback. For spatial alignment and rotation tasks we measured subjective user experience and objective performance with these

  8. Subjective User Experience and Performance with Active Tangibles on a Tabletop Interfaces.

    NARCIS (Netherlands)

    van Erp, Johannes Bernardus Fransiscus; Toet, Alexander; Meijer, Koos; Janssen, Joris; Jong, Arnoud

    We developed active tangibles (Sensators) that can be used in combination with multitouch tabletops and that can provide multisensory (visual, auditory, and vibrotactile) feedback. For spatial alignment and rotation tasks we measured subjective user experience and objective performance with these

  9. Robotic Hand with Flexible Fingers for Grasping Cylindrical Objects

    OpenAIRE

    柴田, 瑞穂

    2015-01-01

    In this manuscript, a robotic hand for grasping a cylindrical object is proposed. This robotic hand has flexible fingers that can hold a cylindrical object during moving. We introduce a grasping strategy for a cylindrical object in terms of state transition graph. In this strategy the robotic hand picks up the cylindrical object utilizing a suction device before the hand grasp the object. We also design the flexible fingers; then, we investigate the validity of this robotic hand via several e...

  10. EMG Biofeedback for online predictive control of grasping force in a myoelectric prosthesis.

    Science.gov (United States)

    Dosen, Strahinja; Markovic, Marko; Somer, Kelef; Graimann, Bernhard; Farina, Dario

    2015-06-19

    Active hand prostheses controlled using electromyography (EMG) signals have been used for decades to restore the grasping function, lost after an amputation. Although myocontrol is a simple and intuitive interface, it is also imprecise due to the stochastic nature of the EMG recorded using surface electrodes. Furthermore, the sensory feedback from the prosthesis to the user is still missing. In this study, we present a novel concept to close the loop in myoelectric prostheses. In addition to conveying the grasping force (system output), we provided to the user the online information about the system input (EMG biofeedback). As a proof-of-concept, the EMG biofeedback was transmitted in the current study using a visual interface (ideal condition). Ten able-bodied subjects and two amputees controlled a state-of-the-art myoelectric prosthesis in routine grasping and force steering tasks using EMG and force feedback (novel approach) and force feedback only (classic approach). The outcome measures were the variability of the generated forces and absolute deviation from the target levels in the routine grasping task, and the root mean square tracking error and the number of sudden drops in the force steering task. During the routine grasping, the novel method when used by able-bodied subjects decreased twofold the force dispersion as well as absolute deviations from the target force levels, and also resulted in a more accurate and stable tracking of the reference force profiles during the force steering. Furthermore, the force variability during routine grasping did not increase for the higher target forces with EMG biofeedback. The trend was similar in the two amputees. The study demonstrated that the subjects, including the two experienced users of a myoelectric prosthesis, were able to exploit the online EMG biofeedback to observe and modulate the myoelectric signals, generating thereby more consistent commands. This allowed them to control the force predictively

  11. Spatiotemporal distribution of location and object effects in the electromyographic activity of upper extremity muscles during reach-to-grasp

    Science.gov (United States)

    Rouse, Adam G.

    2016-01-01

    In reaching to grasp an object, proximal muscles that act on the shoulder and elbow classically have been viewed as transporting the hand to the intended location, while distal muscles that act on the fingers simultaneously shape the hand to grasp the object. Prior studies of electromyographic (EMG) activity in upper extremity muscles therefore have focused, by and large, either on proximal muscle activity during reaching to different locations or on distal muscle activity as the subject grasps various objects. Here, we examined the EMG activity of muscles from the shoulder to the hand, as monkeys reached and grasped in a task that dissociated location and object. We quantified the extent to which variation in the EMG activity of each muscle depended on location, on object, and on their interaction—all as a function of time. Although EMG variation depended on both location and object beginning early in the movement, an early phase of substantial location effects in muscles from proximal to distal was followed by a later phase in which object effects predominated throughout the extremity. Interaction effects remained relatively small. Our findings indicate that neural control of reach-to-grasp may occur largely in two sequential phases: the first, serving to project the entire upper extremity toward the intended location, and the second, acting predominantly to shape the entire extremity for grasping the object. PMID:27009156

  12. Learning Grasp Strategies Composed of Contact Relative Motions

    Science.gov (United States)

    Platt, Robert, Jr.

    2007-01-01

    Of central importance to grasp synthesis algorithms are the assumptions made about the object to be grasped and the sensory information that is available. Many approaches avoid the issue of sensing entirely by assuming that complete information is available. In contrast, this paper proposes an approach to grasp synthesis expressed in terms of units of control that simultaneously change the contact configuration and sense information about the object and the relative manipulator-object pose. These units of control, known as contact relative motions (CRMs), allow the grasp synthesis problem to be recast as an optimal control problem where the goal is to find a strategy for executing CRMs that leads to a grasp in the shortest number of steps. An experiment is described that uses Robonaut, the NASA-JSC space humanoid, to show that CRMs are a viable means of synthesizing grasps. However, because of the limited amount of information that a single CRM can sense, the optimal control problem may be partially observable. This paper proposes expressing the problem as a k-order Markov Decision Process (MDP) and solving it using Reinforcement Learning. This approach is tested in a simulation of a two-contact manipulator that learns to grasp an object. Grasp strategies learned in simulation are tested on the physical Robonaut platform and found to lead to grasp configurations consistently.

  13. Getting a grip on numbers : Numerical magnitude priming in object grasping

    NARCIS (Netherlands)

    Lindemann, Oliver; Abolafia, Juan A.; Girardi, Giovanna; Bekkering, Harold

    2007-01-01

    To investigate the functional connection between numerical cognition and action planning, the authors required participants to perform different grasping responses depending on the parity status of Arabic digits. The results show that precision grip actions were initiated faster in response to small

  14. Predicting subjective vitality and performance in sports: the role of passion and achievement goals.

    Science.gov (United States)

    Li, Chiung-Huang

    2010-06-01

    The major purpose of this study was to test the hypothesized paths from dualistic passions through achievement goals to subjective vitality and performance in sports. 645 high school athletes participated. The proposed structural equation model, with relationships between dualistic passions and subjective vitality and sports performance mediated by achievement goals, fit the data well, especially for mastery-approach and performance-approach goals. Harmonious and obsessive passions may lead athletes to high performance via the adoption of mastery-approach goals. However, these passions seem to have two paths influencing personal functioning: direct effects make players feel energetic, and indirect effects on subjective vitality through adoption of mastery-approach and performance-approach goals.

  15. Reach-to-grasp movement as a minimization process.

    Science.gov (United States)

    Yang, Fang; Feldman, Anatol G

    2010-02-01

    It is known that hand transport and grasping are functionally different but spatially coordinated components of reach-to-grasp (RTG) movements. As an extension of this notion, we suggested that body segments involved in RTG movements are controlled as a coherent ensemble by a global minimization process associated with the necessity for the hand to reach the motor goal. Different RTG components emerge following this process without pre-programming. Specifically, the minimization process may result from the tendency of neuromuscular elements to diminish the spatial gap between the actual arm-hand configuration and its virtual (referent) configuration specified by the brain. The referent configuration is specified depending on the object shape, localization, and orientation. Since the minimization process is gradual, it can be interrupted and resumed following mechanical perturbations, at any phase during RTG movements, including hand closure. To test this prediction of the minimization hypothesis, we asked subjects to reach and grasp a cube placed within the reach of the arm. Vision was prevented during movement until the hand returned to its initial position. As predicted, by arresting wrist motion at different points of hand transport in randomly selected trials, it was possible to halt changes in hand aperture at any phase, not only during hand opening but also during hand closure. Aperture changes resumed soon after the wrist was released. Another test of the minimization hypothesis was made in RTG movements to an object placed beyond the reach of the arm. It has previously been shown (Rossi et al. in J Physiol 538:659-671, 2002) that in such movements, the trunk motion begins to contribute to hand transport only after a critical phase when the shifts in the referent arm configuration have finished (at about the time when hand velocity is maximal). The minimization rule suggests that when the virtual contribution of the arm to hand transport is completed

  16. Getting a grip on reality: Grasping movements directed to real objects and images rely on dissociable neural representations.

    Science.gov (United States)

    Freud, Erez; Macdonald, Scott N; Chen, Juan; Quinlan, Derek J; Goodale, Melvyn A; Culham, Jody C

    2018-01-01

    In the current era of touchscreen technology, humans commonly execute visually guided actions directed to two-dimensional (2D) images of objects. Although real, three-dimensional (3D), objects and images of the same objects share high degree of visual similarity, they differ fundamentally in the actions that can be performed on them. Indeed, previous behavioral studies have suggested that simulated grasping of images relies on different representations than actual grasping of real 3D objects. Yet the neural underpinnings of this phenomena have not been investigated. Here we used functional magnetic resonance imaging (fMRI) to investigate how brain activation patterns differed for grasping and reaching actions directed toward real 3D objects compared to images. Multivoxel Pattern Analysis (MVPA) revealed that the left anterior intraparietal sulcus (aIPS), a key region for visually guided grasping, discriminates between both the format in which objects were presented (real/image) and the motor task performed on them (grasping/reaching). Interestingly, during action planning, the representations of real 3D objects versus images differed more for grasping movements than reaching movements, likely because grasping real 3D objects involves fine-grained planning and anticipation of the consequences of a real interaction. Importantly, this dissociation was evident in the planning phase, before movement initiation, and was not found in any other regions, including motor and somatosensory cortices. This suggests that the dissociable representations in the left aIPS were not based on haptic, motor or proprioceptive feedback. Together, these findings provide novel evidence that actions, particularly grasping, are affected by the realness of the target objects during planning, perhaps because real targets require a more elaborate forward model based on visual cues to predict the consequences of real manipulation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Static, dynamic balance and functional performance in subjects with and without plantar fasciitis

    Directory of Open Access Journals (Sweden)

    Geiseane Aguiar Gonçalves

    Full Text Available Abstract Introduction: Plantar fasciitis (PF is characterized by non-inflammatory degeneration and pain under the heel, and is one of the most common foot complaints. The compensations and adjustments made to decrease the discomfort caused by the disease are clinical findings and can be a factor that contributes to impaired balance and decreased functional performance. Objective: To compare functional performance as well as static and dynamic balance among subjects with and without PF. Methods: The sample consisted of 124 subjects of both sexes aged 20-60 years. Participants were divided into two groups: a bilateral PF group (PFG; n = 62 and a control group (CG, n = 62. The following outcomes were analyzed: static and dynamic balance (using functional tests and functional performance (using a questionnaire. We used Student’s t test for independent samples to compare variables between the groups. The alpha error was set at 0.05. Results: Subjects with PF showed greater impairment in their overall dynamic balance performance (p < 0.001 than the control group, except for left posteromedial movement (p = 0.19. The CG showed showed better functional performance (p < 0.001 than the PF group. There was no difference between groups for the variable static balance on stable (p = 0.160 and unstable surfaces (p = 0.085. Conclusion: Subjects with PF displayed smaller reach distances in the overall Star Excursion Balance Test (SEBT, demonstrating a deficit in dynamic balance and functional performance when compared with healthy subjects.

  18. Grasping without sight: insights from the congenitally blind.

    Directory of Open Access Journals (Sweden)

    Kayla D Stone

    Full Text Available We reach for and grasp different sized objects numerous times per day. Most of these movements are visually-guided, but some are guided by the sense of touch (i.e. haptically-guided, such as reaching for your keys in a bag, or for an object in a dark room. A marked right-hand preference has been reported during visually-guided grasping, particularly for small objects. However, little is known about hand preference for haptically-guided grasping. Recently, a study has shown a reduction in right-hand use in blindfolded individuals, and an absence of hand preference if grasping was preceded by a short haptic experience. These results suggest that vision plays a major role in hand preference for grasping. If this were the case, then one might expect congenitally blind (CB individuals, who have never had a visual experience, to exhibit no hand preference. Two novel findings emerge from the current study: first, the results showed that contrary to our expectation, CB individuals used their right hand during haptically-guided grasping to the same extent as visually-unimpaired (VU individuals did during visually-guided grasping. And second, object size affected hand use in an opposite manner for haptically- versus visually-guided grasping. Big objects were more often picked up with the right hand during haptically-guided, but less often during visually-guided grasping. This result highlights the different demands that object features pose on the two sensory systems. Overall the results demonstrate that hand preference for grasping is independent of visual experience, and they suggest a left-hemisphere specialization for the control of grasping that goes beyond sensory modality.

  19. Task-Independent Cognitive State Transition Detection From Cortical Neurons During 3-D Reach-to-Grasp Movements.

    Science.gov (United States)

    Kang, Xiaoxu; Sarma, Sridevi V; Santaniello, Sabato; Schieber, Marc; Thakor, Nitish V

    2015-07-01

    Complex reach, grasp, and object manipulation tasks require sequential, temporal coordination of movements by neurons in the brain. Detecting cognitive state transitions associated with motor tasks from sequential neural data is pivotal in rehabilitation engineering. The cognitive state detectors proposed thus far rely on task-dependent (TD) models, i.e., the detection strategy exploits a priori knowledge of the movement tasks to determine the actual cognitive states, regardless of whether these cognitive states actually depend on the movement tasks or not. This approach, however, is not viable when the tasks are not known a priori (e.g., the subject performs many different tasks) or there is paucity of neural data for each task. Moreover, some cognitive states (e.g., holding) may be invariant to the movement tasks performed. Here we propose a real-time (online) task-independent (TI) framework to detect cognitive state transitions from spike trains and kinematic measurements. We constructed this detection framework using 452 single-unit neural spike recordings collected via multielectrode arrays in the premotor dorsal and ventral (PMd and PMv) cortical regions of two nonhuman primates performing 3-D multiobject reach-to-grasp tasks. We used the detection latency and accuracy of state transitions to measure the performance. We find that, in both online and offline detection modes: 1) TI models have significantly better performance than corresponding TD models when using neuronal data alone and 2) during movements, the addition of the kinematics history to the TI models further improves detection performance. These findings suggest that TI models may accurately detect cognitive state transitions. Our framework could pave the way for a TI control of neural prosthesis from cortical neurons.

  20. Noninvasive Electroencephalogram Based Control of a Robotic Arm for Reach and Grasp Tasks

    Science.gov (United States)

    Meng, Jianjun; Zhang, Shuying; Bekyo, Angeliki; Olsoe, Jaron; Baxter, Bryan; He, Bin

    2016-12-01

    Brain-computer interface (BCI) technologies aim to provide a bridge between the human brain and external devices. Prior research using non-invasive BCI to control virtual objects, such as computer cursors and virtual helicopters, and real-world objects, such as wheelchairs and quadcopters, has demonstrated the promise of BCI technologies. However, controlling a robotic arm to complete reach-and-grasp tasks efficiently using non-invasive BCI has yet to be shown. In this study, we found that a group of 13 human subjects could willingly modulate brain activity to control a robotic arm with high accuracy for performing tasks requiring multiple degrees of freedom by combination of two sequential low dimensional controls. Subjects were able to effectively control reaching of the robotic arm through modulation of their brain rhythms within the span of only a few training sessions and maintained the ability to control the robotic arm over multiple months. Our results demonstrate the viability of human operation of prosthetic limbs using non-invasive BCI technology.

  1. Identifying relevant feature-action associations for grasping unmodelled objects

    DEFF Research Database (Denmark)

    Thomsen, Mikkel Tang; Kraft, Dirk; Krüger, Norbert

    2015-01-01

    content. The method is provided with a large and structured set of visual features, motivated by the visual hierarchy in primates and finds relevant feature action associations automatically. We apply our method in a simulated environment on three different object sets for the case of grasp affordance......Action affordance learning based on visual sensory information is a crucial problem within the development of cognitive agents. In this paper, we present a method for learning action affordances based on basic visual features, which can vary in their granularity, order of combination and semantic...... learning. For box objects, we achieve a 0.90 success probability, 0.80 for round objects and up to 0.75 for open objects, when presented with novel objects. In this work, we in particular demonstrate the effect of choosing appropriate feature representations. We demonstrate a significant performance...

  2. The effects of energy drink in combination with alcohol on performance and subjective awareness

    OpenAIRE

    Alford, Chris; Hamilton-Morris, Jennifer; Verster, Joris C

    2012-01-01

    Rationale This study investigated the coadministration of an energy drink with alcohol to study the effects on subjective intoxication and objective performance. Objectives This study aims to evaluate the objective and subjective effects of alcohol versus placebo at two alcohol doses, alone and in combination with an energy drink, in a balanced order, placebo-controlled, double-blind design. Methods Two groups of ten healthy volunteers, mean (SD) age of 24 (6.5), participated in the study. On...

  3. Subjective trust, perceived risk and exchange performance in buyer-supplier relationships

    OpenAIRE

    Emanuela Delbufalo

    2012-01-01

    This article offers some theoretical and empirical contributions to the literature on relational exchange by examining the nature of subjective trust and perceived risk in buyer-supplier relationships. The relational view represents the theoretical framework for the research. The study explores the theoretical proposition that subjective trust and perceived risk in buyer-supplier relationships impact on exchange performance through the mediating effects of four sources of relational rents: as...

  4. GRASP65 controls the cis Golgi integrity in vivo

    NARCIS (Netherlands)

    Veenendaal, Tineke; Jarvela, Tim; Grieve, Adam G; van Es, Johan H; Linstedt, Adam D; Rabouille, Catherine

    2014-01-01

    GRASP65 and GRASP55 are peripheral Golgi proteins localized to cis and medial/trans cisternae, respectively. They are implicated in diverse aspects of protein transport and structure related to the Golgi complex, including the stacking of the Golgi stack and/or the linking of mammalian Golgi stacks

  5. Differences in fixations between grasping and viewing objects

    NARCIS (Netherlands)

    Brouwer, A.M.; Franz, V.H.; Gegenfurtner, K.R.

    2009-01-01

    Where exactly do people look when they grasp an object? An object is usually contacted at two locations, whereas the gaze can only be at one location at the time. We investigated participants' fixation locations when they grasp objects with the contact positions of both index finger and thumb being

  6. Grasping social dynamics of participatory innovation

    DEFF Research Database (Denmark)

    Sproedt, Henrik; Boer, Laurens

    2011-01-01

    and stakeholders themselves to understand their relations and what it means to participate. We argue that we can grasp these social dynamics of participatory innovation through play. From a management perspective we study how playing games helps us to understand these dynamics, while from an interaction design......The key element in participatory innovation is to understand innovation as a social problem solving process between different stakeholders. The social dynamics amongst stakeholders are fundamental to the participatory process and outcome, and it’s therefore beneficial for facilitators...... perspective we study how a game that addresses these dynamics can be designed. We describe a case of a game, designed for the Participatory Innovation Conference of 2011 in Sønderborg, Denmark. The game was particularly designed around the themes of conflict and interdependence, captured by the dilemma of co...

  7. Grasping social dynamics of participatory innovation

    DEFF Research Database (Denmark)

    Sproedt, Henrik; Boer, Laurens

    2011-01-01

    The key element in participatory innovation is to understand innovation as a social problem solving process between different stakeholders. The social dynamics amongst stakeholders are fundamental to the participatory process and outcome, and it’s therefore beneficial for facilitators...... and stakeholders themselves to understand their relations and what it means to participate. We argue that we can grasp these social dynamics of participatory innovation through play. From a management perspective we study how playing games helps us to understand these dynamics, while from an interaction design...... perspective we study how a game that addresses these dynamics can be designed. We describe a case of a game, designed for the Participatory Innovation Conference of 2011 in Sønderborg, Denmark. The game was particularly designed around the themes of conflict and interdependence, captured by the dilemma of co...

  8. Improved automated perimetry performance in elderly subjects after listening to Mozart

    Directory of Open Access Journals (Sweden)

    Junia Cabral Marques

    2009-01-01

    Full Text Available PURPOSE: To evaluate the performance of automated perimetry of elderly subjects naïve to AP after listening to a Mozart sonata. INTRODUCTION: Automated perimetry (AP is a psychophysical test used to assess visual fields in patients with neurological disorders and glaucoma. In a previous study, Fiorelli et al. showed that young subjects who listened to a Mozart sonata prior to undergoing AP performed better in terms of reliability than those who did not listen to the sonata. METHODS: Fifty-two AP-naïve, normal subjects underwent Automated perimetry (SITA 24-2. The study group (25 subjects underwent AP after listening to Mozart's Sonata for Two Pianos in D Major, and the control group (27 subjects underwent Automated perimetry without prior exposure to the music. RESULTS: The study group had significantly lower false negative rates and a lower visual field reliability score than the controls (P=0.04 and P=0.04, respectively. The test time was shorter for the study group (P=0.03. DISCUSSION: This study shows that elderly subjects, when exposed to the Mozart sonata immediately before AP testing, have lower false negative rates and lower visual field reliability scores when compared with an age- and gender-matched control group. Our results differ from those of Fiorelli et al. who found lower false positive rates and less fixation loss in addition to lower false negative rates. CONCLUSION: Listening to a Mozart sonata seems to improve automated perimetry reliability in elderly subjects.

  9. Improved automated perimetry performance in elderly subjects after listening to Mozart.

    Science.gov (United States)

    Marques, Junia Cabral; Vanessa, Adriana Chaves Oliveira; Fiorelli, Macedo Batista; Kasahara, Niro

    2009-01-01

    To evaluate the performance of automated perimetry of elderly subjects naïve to AP after listening to a Mozart sonata. Automated perimetry (AP) is a psychophysical test used to assess visual fields in patients with neurological disorders and glaucoma. In a previous study, Fiorelli et al. showed that young subjects who listened to a Mozart sonata prior to undergoing AP performed better in terms of reliability than those who did not listen to the sonata. Fifty-two AP-naïve, normal subjects underwent Automated perimetry (SITA 24-2). The study group (25 subjects) underwent AP after listening to Mozart's Sonata for Two Pianos in D Major, and the control group (27 subjects) underwent Automated perimetry without prior exposure to the music. The study group had significantly lower false negative rates and a lower visual field reliability score than the controls (P=0.04 and P=0.04, respectively). The test time was shorter for the study group (P=0.03). This study shows that elderly subjects, when exposed to the Mozart sonata immediately before AP testing, have lower false negative rates and lower visual field reliability scores when compared with an age- and gender-matched control group. Our results differ from those of Fiorelli et al. who found lower false positive rates and less fixation loss in addition to lower false negative rates. Listening to a Mozart sonata seems to improve automated perimetry reliability in elderly subjects.

  10. Fast Grasp Contact Computation for a Serial Robot

    Science.gov (United States)

    Shi, Jianying (Inventor); Hargrave, Brian (Inventor); Diftler, Myron A. (Inventor)

    2015-01-01

    A system includes a controller and a serial robot having links that are interconnected by a joint, wherein the robot can grasp a three-dimensional (3D) object in response to a commanded grasp pose. The controller receives input information, including the commanded grasp pose, a first set of information describing the kinematics of the robot, and a second set of information describing the position of the object to be grasped. The controller also calculates, in a two-dimensional (2D) plane, a set of contact points between the serial robot and a surface of the 3D object needed for the serial robot to achieve the commanded grasp pose. A required joint angle is then calculated in the 2D plane between the pair of links using the set of contact points. A control action is then executed with respect to the motion of the serial robot using the required joint angle.

  11. Grasping devices and methods in automated production processes

    DEFF Research Database (Denmark)

    Fantoni, Gualtiero; Santochi, Marco; Dini, Gino

    2014-01-01

    In automated production processes grasping devices and methods play a crucial role in the handling of many parts, components and products. This keynote paper starts with a classification of grasping phases, describes how different principles are adopted at different scales in different applications...... and continues explaining different releasing strategies and principles. Then the paper classifies the numerous sensors used to monitor the effectiveness of grasping (part presence, exchanged force, stick-slip transitions, etc.). Later the grasping and releasing problems in different fields (from mechanical...... assembly to disassembly, from aerospace to food industry, from textile to logistics) are discussed. Finally, the most recent research is reviewed in order to introduce the new trends in grasping. They provide an outlook on the future of both grippers and robotic hands in automated production processes. (C...

  12. Autonomous Object Manipulation Using a Soft Planar Grasping Manipulator.

    Science.gov (United States)

    Katzschmann, Robert K; Marchese, Andrew D; Rus, Daniela

    2015-12-01

    This article presents the development of an autonomous motion planning algorithm for a soft planar grasping manipulator capable of grasp-and-place operations by encapsulation with uncertainty in the position and shape of the object. The end effector of the soft manipulator is fabricated in one piece without weakening seams using lost-wax casting instead of the commonly used multilayer lamination process. The soft manipulation system can grasp randomly positioned objects within its reachable envelope and move them to a desired location without human intervention. The autonomous planning system leverages the compliance and continuum bending of the soft grasping manipulator to achieve repeatable grasps in the presence of uncertainty. A suite of experiments is presented that demonstrates the system's capabilities.

  13. A Comparison of Tandem Walk Performance Between Bed Rest Subjects and Astronauts

    Science.gov (United States)

    Miller, Chris; Peters, Brian; Kofman, Igor; Philips, Tiffany; Batson, Crystal; Cerisano, Jody; Fisher, Elizabeth; Mulavara, Ajitkumar; Feiveson, Alan; Reschke, Millard; hide

    2015-01-01

    Astronauts experience a microgravity environment during spaceflight, which results in a central reinterpretation of both vestibular and body axial-loading information by the sensorimotor system. Subjects in bed rest studies lie at 6deg head-down in strict bed rest to simulate the fluid shift and gravity-unloading of the microgravity environment. However, bed rest subjects still sense gravity in the vestibular organs. Therefore, bed rest isolates the axial-unloading component, thus allowing for the direct study of its effects. The Tandem Walk is a standard sensorimotor test of dynamic postural stability. In a previous abstract, we compared performance on a Tandem Walk test between bed rest control subjects, and short- and long-duration astronauts both before and after flight/bed rest using a composite index of performance, called the Tandem Walk Parameter (TWP), that takes into account speed, accuracy, and balance control. This new study extends the previous data set to include bed rest subjects who performed exercise countermeasures. The purpose of this study was to compare performance during the Tandem Walk test between bed rest subjects (with and without exercise), short-duration (Space Shuttle) crewmembers, and long-duration International Space Station (ISS) crewmembers at various time points during their recovery from bed rest or spaceflight.

  14. Connections of Grasping and Horizontal Hand Movements with Articulation in Czech Speakers

    Czech Academy of Sciences Publication Activity Database

    Tiainen, M.; Lukavský, Jiří; Tiippana, K.; Vainio, M.; Šimko, J.; Felisberti, F.; Vainio, L.

    2017-01-01

    Roč. 8, duben (2017), s. 1-10, č. článku 516. ISSN 1664-1078 Grant - others:AV ČR(CZ) StrategieAV21/14 Program:StrategieAV Institutional support: RVO:68081740 Keywords : articulation * motor actions * language * grasping * manual gestures * speech * manual actions Subject RIV: AN - Psychology Impact factor: 2.323, year: 2016

  15. Speech perception performance of subjects with type I diabetes mellitus in noise

    Directory of Open Access Journals (Sweden)

    Bárbara Cristiane Sordi Silva

    Full Text Available Abstract Introduction: Diabetes mellitus (DM is a chronic metabolic disorder of various origins that occurs when the pancreas fails to produce insulin in sufficient quantities or when the organism fails to respond to this hormone in an efficient manner. Objective: To evaluate the speech recognition in subjects with type I diabetes mellitus (DMI in quiet and in competitive noise. Methods: It was a descriptive, observational and cross-section study. We included 40 participants of both genders aged 18-30 years, divided into a control group (CG of 20 healthy subjects with no complaints or auditory changes, paired for age and gender with the study group, consisting of 20 subjects with a diagnosis of DMI. First, we applied basic audiological evaluations (pure tone audiometry, speech audiometry and immittance audiometry for all subjects; after these evaluations, we applied Sentence Recognition Threshold in Quiet (SRTQ and Sentence Recognition Threshold in Noise (SRTN in free field, using the List of Sentences in Portuguese test. Results: All subjects showed normal bilateral pure tone threshold, compatible speech audiometry and "A" tympanometry curve. Group comparison revealed a statistically significant difference for SRTQ (p = 0.0001, SRTN (p < 0.0001 and the signal-to-noise ratio (p < 0.0001. Conclusion: The performance of DMI subjects in SRTQ and SRTN was worse compared to the subjects without diabetes.

  16. Testing of visual field with virtual reality goggles in manual and visual grasp modes.

    Science.gov (United States)

    Wroblewski, Dariusz; Francis, Brian A; Sadun, Alfredo; Vakili, Ghazal; Chopra, Vikas

    2014-01-01

    Automated perimetry is used for the assessment of visual function in a variety of ophthalmic and neurologic diseases. We report development and clinical testing of a compact, head-mounted, and eye-tracking perimeter (VirtualEye) that provides a more comfortable test environment than the standard instrumentation. VirtualEye performs the equivalent of a full threshold 24-2 visual field in two modes: (1) manual, with patient response registered with a mouse click, and (2) visual grasp, where the eye tracker senses change in gaze direction as evidence of target acquisition. 59 patients successfully completed the test in manual mode and 40 in visual grasp mode, with 59 undergoing the standard Humphrey field analyzer (HFA) testing. Large visual field defects were reliably detected by VirtualEye. Point-by-point comparison between the results obtained with the different modalities indicates: (1) minimal systematic differences between measurements taken in visual grasp and manual modes, (2) the average standard deviation of the difference distributions of about 5 dB, and (3) a systematic shift (of 4-6 dB) to lower sensitivities for VirtualEye device, observed mostly in high dB range. The usability survey suggested patients' acceptance of the head-mounted device. The study appears to validate the concepts of a head-mounted perimeter and the visual grasp mode.

  17. Optimal capture occasion determination and trajectory generation for space robots grasping tumbling objects

    Science.gov (United States)

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

    2017-07-01

    This paper presents an optimal trajectory planning scheme for robotic capturing of a tumbling object. Motion planning of a space robot is much more complex than that of a fixed-based robot, due to the dynamic coupling between the manipulator and its base. In this work, the Path Independent Workspace (PIW), in which no dynamic singularity occurs, and Path Dependent Workspace (PDW) of the space robot are first calculated by the proposed algorithm. The motion equations of the tumbling object are formulated based on the Euler dynamics equations and the quaternion, which are used to predict the long-term motion of a grasping point on the tumbling object. Subsequently, the obtained PIW workspace and predicted motion trajectories are used to plan the trajectory of the end-effector to intercept the grasping point with zero relative velocity (to avoid impact) in an optimal way. In order to avoid dynamic singularity occurring at the capture moment, the optimal capture occasion is first determined by three proposed criterions guaranteeing the capture can be safely, reliably and rapidly performed, then the optimal trajectory of the end-effector is generated minimizing a cost function which acts as a constraint on acceleration magnitude. Simulations are presented to demonstrate the trajectory planning scheme for a space robot with a 3-degree of freedom (DOF) manipulator grasping a tumbling satellite, the results show that the manipulator end-effector can smoothly intercept the grasping point on the tumbling satellite with zero relative velocity.

  18. Testing of Visual Field with Virtual Reality Goggles in Manual and Visual Grasp Modes

    Directory of Open Access Journals (Sweden)

    Dariusz Wroblewski

    2014-01-01

    Full Text Available Automated perimetry is used for the assessment of visual function in a variety of ophthalmic and neurologic diseases. We report development and clinical testing of a compact, head-mounted, and eye-tracking perimeter (VirtualEye that provides a more comfortable test environment than the standard instrumentation. VirtualEye performs the equivalent of a full threshold 24-2 visual field in two modes: (1 manual, with patient response registered with a mouse click, and (2 visual grasp, where the eye tracker senses change in gaze direction as evidence of target acquisition. 59 patients successfully completed the test in manual mode and 40 in visual grasp mode, with 59 undergoing the standard Humphrey field analyzer (HFA testing. Large visual field defects were reliably detected by VirtualEye. Point-by-point comparison between the results obtained with the different modalities indicates: (1 minimal systematic differences between measurements taken in visual grasp and manual modes, (2 the average standard deviation of the difference distributions of about 5 dB, and (3 a systematic shift (of 4–6 dB to lower sensitivities for VirtualEye device, observed mostly in high dB range. The usability survey suggested patients’ acceptance of the head-mounted device. The study appears to validate the concepts of a head-mounted perimeter and the visual grasp mode.

  19. Effects of EVA spacesuit glove on grasping and pinching tasks

    Science.gov (United States)

    Appendino, Silvia; Battezzato, Alessandro; Chen Chen, Fai; Favetto, Alain; Mousavi, Mehdi; Pescarmona, Francesco

    2014-03-01

    The human hand has a wide range of degrees of freedom, allowing a great variety of movements, and is also one of the most sensitive parts of the human body. Due to these characteristics, it is the most important tool for astronauts to perform extravehicular activities (EVA). However, astronauts must wear mandatory EVA equipment to be protected from the harsh conditions in space and this strongly reduces hand performance, in particular as regards dexterity, tactile perception, mobility and fatigue. Several studies have been conducted to determine the influence of the EVA glove on manual capabilities, both in the past and more recently. This study presents experimental data regarding the performance decline occurring in terms of force and fatigue in the execution of grasping and pinching tasks when wearing an EVA glove, in pressurized and unpressurized conditions, compared with barehanded potential. Results show that wearing the unpressurized EVA glove hinders grip and lateral pinch performances, dropping exerted forces to about 50-70%, while it barely affects two- and three-finger pinch performances. On the other hand, wearing the pressurized glove worsens performances in all cases, reducing forces to about 10-30% of barehanded potential. The results are presented and compared with the previous literature.

  20. Assessment of pilot workload - Converging measures from performance based, subjective and psychophysiological techniques

    Science.gov (United States)

    Kramer, Arthur F.; Sirevaag, Erik J.; Braune, Rolf

    1986-01-01

    This study explores the relationship between the P300 component of the event-related brain potential (ERP) and the processing demands of a complex real-world task. Seven male volunteers enrolled in an Instrument Flight Rule (IFR) aviation course flew a series of missions in a single engine fixed-based simulator. In dual task conditions subjects were also required to discriminate between two tones differing in frequency. ERPs time-locked to the tones, subjective effort ratings and overt performance measures were collected during two 45 min flights differing in difficulty (manipulated by varying both atmospheric conditions and instrument reliability). The more difficult flight was associated with poorer performance, increased subjective effort ratings, and smaller secondary task P300s. Within each flight, P300 amplitude was negatively correlated with deviations from command headings indicating that P300 amplitude was a sensitive workload metric both between and within the flight missions.

  1. Motor performance during and following acute alcohol intoxication in healthy non-alcoholic subjects

    DEFF Research Database (Denmark)

    Poulsen, Mette Buch; Jakobsen, Johannes Klitgaard; Andersen, Henning

    2007-01-01

    Chronic alcohol abuse has adverse effects on skeletal muscle, and reduced muscle strength is frequently seen in chronic alcoholics. In this study the acute effects of moderate alcohol intoxication on motor performance was evaluated in 19 non-alcoholic healthy subjects (10 women, 9 men). A randomi...... of moderate alcohol intoxication (1,4 g/l) does not impair motor performance, and no accelerated exercise-induced muscle damage is seen. Udgivelsesdato: 2007-Nov...

  2. Student Performance on the NBME Part II Subtest and Subject Examination in Obstetrics-Gynecology.

    Science.gov (United States)

    Metheny, William P.; Holzman, Gerald B.

    1988-01-01

    Comparison of the scores of 342 third-year medical students on the National Board of Medical Examiners subject examination and the Part II subtest on obstetrics-gynecology found significantly better performance on the former, suggesting a need to interpret the scores differently. (Author/MSE)

  3. Multimodal decoding and congruent sensory information enhance reaching performance in subjects with cervical spinal cord injury

    Directory of Open Access Journals (Sweden)

    Elaine Anna Corbett

    2014-05-01

    Full Text Available Cervical spinal cord injury (SCI paralyzes muscles of the hand and arm, making it difficult to perform activities of daily living. Restoring the ability to reach can dramatically improve quality of life for people with cervical SCI. Any reaching system requires a user interface to decode parameters of an intended reach, such as trajectory and target. A challenge in developing such decoders is that often few physiological signals related to the intended reach remain under voluntary control, especially in patients with high cervical injuries. Furthermore, the decoding problem changes when the user is controlling the motion of their limb, as opposed to an external device. The purpose of this study was to investigate the benefits of combining disparate signal sources to control reach in people with a range of impairments, and to consider the effect of two feedback approaches. Subjects with cervical SCI performed robot-assisted reaching, controlling trajectories with either shoulder electromyograms (EMGs or EMGs combined with gaze. We then evaluated how reaching performance was influenced by task-related sensory feedback, testing the EMG-only decoder in two conditions. The first involved moving the arm with the robot, providing congruent sensory feedback through their remaining sense of proprioception. In the second, the subjects moved the robot without the arm attached, as in applications that control external devices. We found that the multimodal decoding algorithm worked well for all subjects, enabling them to perform straight, accurate reaches. The inclusion of gaze information, used to estimate target location, was especially important for the most impaired subjects. In the absence of gaze information, congruent sensory feedback improved performance. These results highlight the importance of proprioceptive feedback, and suggest that multi-modal decoders are likely to be most beneficial for highly impaired subjects and in tasks where such

  4. The detailed aerosol properties derived using GRASP Algorithm from multi-angular polarimetric POLDER/PARASOL observations

    Science.gov (United States)

    Dubovik, Oleg; Litvinov, Pavel; Lapyonok, Tatyana; Ducos, Fabrice; Fuertes, David; Huang, Xin; Derimian, Yevgeny; Ovigneur, Bertrand; Descloitres, Jacques

    2015-04-01

    The presentation introduces a new aerosol product derived from multi-angular polarimetric POLDER/PARASOL observations using recently developed GRASP algorithm The GRASP (Generalized Retrieval of Aerosol and Surface Properties) algorithm described by Dubovik et al. (2011, 2014) derives an extended set of aerosol parameters including detailed particle size distribution, spectral refractive index, single scattering albedo and the fraction of non-spherical particles. Over land GRASP simultaneously retrieves properties of both aerosol and underlying surface. The robust performance of algorithm was illustrated in a series of numerical tests and real data case studies. However, the algorithm is significantly slower than conventional look-up-table retrievals because it performs all radiative transfer calculations on-line. This is why the application of the algorithm for processing large volumes of satellite data was considered as unacceptably challenging task. During two last years GRASP algorithm and its operational retrieval environment has been significantly optimized, improved and adapted for processing extended set of observational data. Hence, here we demonstrate the first results of GRASP aerosol products obtained from large data sets of PARASOL/POLDER observations. It should be noted that in addition the core retrieved aerosol and surface parameters GRASP output may include a variety of user-oriented products including values of daily fluxes and aerosol radiative forcing. 1. Dubovik, O., M. Herman, A. Holdak, T. Lapyonok, D. Tanré, J. L. Deuzé, F. Ducos, A. Sinyuk, and A. Lopatin, "Statistically optimized inversion algorithm for enhanced retrieval of aerosol properties from spectral multi-angle polarimetric satellite observations", Atmos. Meas. Tech., 4, 975-1018, 2011. 2. Dubovik, O., T. Lapyonok, P. Litvinov, M. Herman, D. Fuertes, F. Ducos, A. Lopatin, A. Chaikovsky, B. Torres, Y. Derimian, X. Huang, M. Aspetsberger, and C. Federspiel "GRASP: a versatile

  5. Improved Automated Perimetry Performance in Elderly Subjects after Listening To Mozart

    Science.gov (United States)

    Marques, Junia Cabral; Vanessa, Adriana Chaves Oliveira; Fiorelli, Macedo Batista; Kasahara, Niro

    2009-01-01

    PURPOSE: To evaluate the performance of automated perimetry of elderly subjects naïve to AP after listening to a Mozart sonata. INTRODUCTION: Automated perimetry (AP) is a psychophysical test used to assess visual fields in patients with neurological disorders and glaucoma. In a previous study, Fiorelli et al. showed that young subjects who listened to a Mozart sonata prior to undergoing AP performed better in terms of reliability than those who did not listen to the sonata. METHODS: Fifty-two AP-naïve, normal subjects underwent Automated perimetry (SITA 24-2). The study group (25 subjects) underwent AP after listening to Mozart’s Sonata for Two Pianos in D Major, and the control group (27 subjects) underwent Automated perimetry without prior exposure to the music. RESULTS: The study group had significantly lower false negative rates and a lower visual field reliability score than the controls (P=0.04 and P=0.04, respectively). The test time was shorter for the study group (P=0.03). DISCUSSION: This study shows that elderly subjects, when exposed to the Mozart sonata immediately before AP testing, have lower false negative rates and lower visual field reliability scores when compared with an age- and gender-matched control group. Our results differ from those of Fiorelli et al. who found lower false positive rates and less fixation loss in addition to lower false negative rates. CONCLUSION: Listening to a Mozart sonata seems to improve automated perimetry reliability in elderly subjects. PMID:19606243

  6. Monocular and binocular reading performance in subjects with normal binocular vision.

    Science.gov (United States)

    Johansson, Jan; Pansell, Tony; Ygge, Jan; Seimyr, Gustaf Öqvist

    2014-07-01

    It is well known that problems with binocular vision can cause issues for reading; less known is to what extent binocular vision improves reading performance. The purpose of this study was to explore the role of binocularity by directly comparing monocular and binocular reading in subjects with typical reading skills and normal binocular vision. A secondary purpose was to assess any asymmetry in monocular performance and its association with the sighting dominant eye. In a balanced repeated measures experiment, 18 subjects read paragraphs of text under monocular and binocular conditions. All subjects went through an optometric examination before inclusion. Reading speed and eye movements were recorded with an eye tracker. The mean difference in reading speed (2.1 per cent) between monocular (dominant and non-dominant eye averaged) and binocular reading speed was not significant. A significant difference in reading speed was found between binocular and the non-dominant eye, as determined by the far sighting test (p = 0.03). Monocular reading showed significantly increased (8.9 per cent) fixation duration (p binocular vision, there is no marked enhancement in reading performance by binocular vision when reading paragraphs of text. Furthermore, the monocular reading performance appears to be close to equal and any small differences in performance appear not to be strongly associated with ocular dominance. © 2014 The Authors. Clinical and Experimental Optometry © 2014 Optometrists Association Australia.

  7. Precompetitive state anxiety, objective and subjective performance, and causal attributions in competitive swimmers.

    Science.gov (United States)

    Polman, Remco; Rowcliffe, Naomi; Borkoles, Erika; Levy, Andrew

    2007-02-01

    This study investigated the nature of the relationship between precompetitive state anxiety (CSAI-2C), subjective (race position) and objective (satisfaction) performance outcomes, and self-rated causal attributions (CDS-IIC) for performance in competitive child swimmers. Race position, subjective satisfaction, self-confidence, and, to a lesser extent, cognitive state anxiety (but not somatic state anxiety) were associated with the attributions provided by the children for their swimming performance. The study partially supported the self-serving bias hypothesis; winners used the ego-enhancing attributional strategy, but the losers did not use an ego-protecting attributional style. Age but not gender appeared to influence the attributions provided in achievement situations.

  8. Learning Objects and Grasp Affordances through Autonomous Exploration

    DEFF Research Database (Denmark)

    Kraft, Dirk; Detry, Renaud; Pugeault, Nicolas

    2009-01-01

    We describe a system for autonomous learning of visual object representations and their grasp affordances on a robot-vision system. It segments objects by grasping and moving 3D scene features, and creates probabilistic visual representations for object detection, recognition and pose estimation...... image sequences as well as (3) a number of built-in behavioral modules on the one hand, and autonomous exploration on the other hand, the system is able to generate object and grasping knowledge through interaction with its environment....

  9. Single subject analyses reveal consistent recruitment of frontal operculum in performance monitoring.

    Science.gov (United States)

    Amiez, Céline; Wutte, Magdalena G; Faillenot, Isabelle; Petrides, Michael; Burle, Boris; Procyk, Emmanuel

    2016-06-01

    There are continuing uncertainties regarding whether performance monitoring recruits the anterior insula (aI) and/or the frontal operculum (fO). The proximity and morphological complexity of these two regions make proper identification and isolation of the loci of activation extremely difficult. The use of group averaging methods in human neuroimaging might contribute to this problem. The result has been heterogeneous labeling of this region as aI, fO, or aI/fO, and a discussion of results oriented towards either cognitive or interoceptive functions depending on labeling. In the present article, we adapted the spatial preprocessing of functional magnetic resonance imaging data to account for group averaging artifacts and performed a subject-by-subject analysis in three performance monitoring tasks. Results show that functional activity related to feedback or action monitoring consistently follows local morphology in this region and demonstrate that the activity is located predominantly in the fO rather than in the aI. From these results, we propose that a full understanding of the respective role of aI and fO would benefit from increased spatial resolution and subject-by-subject analysis. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Subjective Evaluation of Packet Service Performance in UMTS and Heterogeneous Networks

    DEFF Research Database (Denmark)

    Teyeb, Oumer Mohammed; Sørensen, Troels Bundgaard; Mogensen, Preben

    2006-01-01

    Quality of Service (QoS) in mobile telecommunication systems is usually identified by some basic performance metrics such as delay, throughput and jitter. However, the main impact of service quality is on the end user, and as such a detailed study of service performance should involve the end user....... In this paper, such an approach is taken where subjective performance evaluation is undertaken for web browsing and video streaming services in Universal Mobile Telecommunication System (UMTS) and a heterogeneous network comprised of UMTS and Wireless LAN (WLAN). Using a real-time network emulation testbed...

  11. Performance effects and subjective disturbance of speech in acoustically different office types--a laboratory experiment.

    Science.gov (United States)

    Haka, M; Haapakangas, A; Keränen, J; Hakala, J; Keskinen, E; Hongisto, V

    2009-12-01

    This study examined how the intelligibility of irrelevant speech, determined with the Speech Transmission Index (STI), affects demanding cognitive task performance. Experiment was carried out in a laboratory that resembled an open-plan office. Three speech conditions were tested corresponding to a private office (STI = 0.10), an acoustically excellent open office (STI = 0.35) and an acoustically poor open office (STI = 0.65). All conditions were presented at equal level, 48 dBA. The STI was adjusted by the relative levels of speech and masking sound. Thirty-seven students participated in the experiment that lasted for 4 h. All participants performed five tasks in each of the three speech conditions. Questionnaires were used to assess subjective perceptions of the speech conditions. Performance in the operation span task, the serial recall and the activation of prior knowledge from long-term memory were deteriorated in the speech condition with the highest speech intelligibility (STI = 0.65) in comparison with the other two conditions (STI = 0.10 and STI = 0.35). Unlike performance measures, questionnaire results showed consistent differences among all three speech conditions, i.e. subjective disturbance increased with ascending speech intelligibility. Thus, subjective comfort was disturbed more easily than performance. The results support the use of STI as an essential room acoustic design measure in open-plan offices. Reduction of speech intelligibility in office environments by proper acoustic design would be beneficial in terms of both work performance and subjective comfort. Proper acoustic design requires both the use of high acoustic absorption and an appropriate masking sound.

  12. Pantomime-grasping: Advance knowledge of haptic feedback availability supports an absolute visuo-haptic calibration

    Directory of Open Access Journals (Sweden)

    Shirin eDavarpanah Jazi

    2016-05-01

    Full Text Available An emerging issue in movement neurosciences is whether haptic feedback influences the nature of the information supporting a simulated grasping response (i.e., pantomime-grasping. In particular, recent work by our group contrasted pantomime-grasping responses performed with (i.e., PH+ trials and without (i.e., PH- trials terminal haptic feedback in separate blocks of trials. Results showed that PH- trials were mediated via relative visual information. In contrast, PH+ trials showed evidence of an absolute visuo-haptic calibration – a finding attributed to an error signal derived from a comparison between expected and actual haptic feedback (i.e., an internal forward model. The present study examined whether advanced knowledge of haptic feedback availability influences the aforementioned calibration process. To that end, PH- and PH+ trials were completed in separate blocks (i.e., the feedback schedule used in our group’s previous study and a block wherein PH- and PH+ trials were randomly interleaved on a trial-by-trial basis (i.e., random feedback schedule. In other words, the random feedback schedule precluded participants from predicting whether haptic feedback would be available at the movement goal location. We computed just-noticeable-difference (JND values to determine whether responses adhered to, or violated, the relative psychophysical principles of Weber’s law. Results for the blocked feedback schedule replicated our group’s previous work, whereas in the random feedback schedule PH- and PH+ trials were supported via relative visual information. Accordingly, we propose that a priori knowledge of haptic feedback is necessary to support an absolute visuo-haptic calibration. Moreover, our results demonstrate that the presence and expectancy of haptic feedback is an important consideration in contrasting the behavioral and neural properties of natural and stimulated (i.e., pantomime-grasping grasping.

  13. The use of underactuation in prosthetic grasping

    Directory of Open Access Journals (Sweden)

    P. J. Kyberd

    2011-02-01

    Full Text Available Underactuation as a method of driving prosthetic hands has a long history. The pragmatic requirements of such a device to be light enough to be worn and used regularly have meant that any multi degree of freedom prosthetic hand must have fewer actuators than the usable degrees of freedom. Aesthetics ensures that while the hand needs five fingers, five actuators have considerable mass, and only in recent years has it even been possible to construct a practical anthropomorphic hand with five motors. Thus there is an important trade off as to which fingers are driven, and which joints on which fingers are actuated, and how the forces are distributed to create a functional device. This paper outlines some of the historical solutions created for this problem and includes those designs of recent years that are now beginning to be used in the commercial environment.

    This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010, 19 August 2010, Montréal, Canada.

  14. Evaluation of Subjective and Objective Performance Metrics for Haptically Controlled Robotic Systems

    Directory of Open Access Journals (Sweden)

    Cong Dung Pham

    2014-07-01

    Full Text Available This paper studies in detail how different evaluation methods perform when it comes to describing the performance of haptically controlled mobile manipulators. Particularly, we investigate how well subjective metrics perform compared to objective metrics. To find the best metrics to describe the performance of a control scheme is challenging when human operators are involved; how the user perceives the performance of the controller does not necessarily correspond to the directly measurable metrics normally used in controller evaluation. It is therefore important to study whether there is any correspondence between how the user perceives the performance of a controller, and how it performs in terms of directly measurable metrics such as the time used to perform a task, number of errors, accuracy, and so on. To perform these tests we choose a system that consists of a mobile manipulator that is controlled by an operator through a haptic device. This is a good system for studying different performance metrics as the performance can be determined by subjective metrics based on feedback from the users, and also as objective and directly measurable metrics. The system consists of a robotic arm which provides for interaction and manipulation, which is mounted on a mobile base which extends the workspace of the arm. The operator thus needs to perform both interaction and locomotion using a single haptic device. While the position of the on-board camera is determined by the base motion, the principal control objective is the motion of the manipulator arm. This calls for intelligent control allocation between the base and the manipulator arm in order to obtain intuitive control of both the camera and the arm. We implement three different approaches to the control allocation problem, i.e., whether the vehicle or manipulator arm actuation is applied to generate the desired motion. The performance of the different control schemes is evaluated, and our

  15. Force Myography for Monitoring Grasping in Individuals with Stroke with Mild to Moderate Upper-Extremity Impairments: A Preliminary Investigation in a Controlled Environment

    Science.gov (United States)

    Sadarangani, Gautam P.; Jiang, Xianta; Simpson, Lisa A.; Eng, Janice J.; Menon, Carlo

    2017-01-01

    There is increasing research interest in technologies that can detect grasping, to encourage functional use of the hand as part of daily living, and thus promote upper-extremity motor recovery in individuals with stroke. Force myography (FMG) has been shown to be effective for providing biofeedback to improve fine motor function in structured rehabilitation settings, involving isolated repetitions of a single grasp type, elicited at a predictable time, without upper-extremity movements. The use of FMG, with machine learning techniques, to detect and distinguish between grasping and no grasping, continues to be an active area of research, in healthy individuals. The feasibility of classifying FMG for grasp detection in populations with upper-extremity impairments, in the presence of upper-extremity movements, as would be expected in daily living, has yet to be established. We explore the feasibility of FMG for this application by establishing and comparing (1) FMG-based grasp detection accuracy and (2) the amount of training data necessary for accurate grasp classification, in individuals with stroke and healthy individuals. FMG data were collected using a flexible forearm band, embedded with six force-sensitive resistors (FSRs). Eight participants with stroke, with mild to moderate upper-extremity impairments, and eight healthy participants performed 20 repetitions of three tasks that involved reaching, grasping, and moving an object in different planes of movement. A validation sensor was placed on the object to label data as corresponding to a grasp or no grasp. Grasp detection performance was evaluated using linear and non-linear classifiers. The effect of training set size on classification accuracy was also determined. FMG-based grasp detection demonstrated high accuracy of 92.2% (σ = 3.5%) for participants with stroke and 96.0% (σ = 1.6%) for healthy volunteers using a support vector machine (SVM). The use of a training set that was 50% the size of

  16. Force Myography for Monitoring Grasping in Individuals with Stroke with Mild to Moderate Upper-Extremity Impairments: A Preliminary Investigation in a Controlled Environment

    Directory of Open Access Journals (Sweden)

    Gautam P. Sadarangani

    2017-07-01

    Full Text Available There is increasing research interest in technologies that can detect grasping, to encourage functional use of the hand as part of daily living, and thus promote upper-extremity motor recovery in individuals with stroke. Force myography (FMG has been shown to be effective for providing biofeedback to improve fine motor function in structured rehabilitation settings, involving isolated repetitions of a single grasp type, elicited at a predictable time, without upper-extremity movements. The use of FMG, with machine learning techniques, to detect and distinguish between grasping and no grasping, continues to be an active area of research, in healthy individuals. The feasibility of classifying FMG for grasp detection in populations with upper-extremity impairments, in the presence of upper-extremity movements, as would be expected in daily living, has yet to be established. We explore the feasibility of FMG for this application by establishing and comparing (1 FMG-based grasp detection accuracy and (2 the amount of training data necessary for accurate grasp classification, in individuals with stroke and healthy individuals. FMG data were collected using a flexible forearm band, embedded with six force-sensitive resistors (FSRs. Eight participants with stroke, with mild to moderate upper-extremity impairments, and eight healthy participants performed 20 repetitions of three tasks that involved reaching, grasping, and moving an object in different planes of movement. A validation sensor was placed on the object to label data as corresponding to a grasp or no grasp. Grasp detection performance was evaluated using linear and non-linear classifiers. The effect of training set size on classification accuracy was also determined. FMG-based grasp detection demonstrated high accuracy of 92.2% (σ = 3.5% for participants with stroke and 96.0% (σ = 1.6% for healthy volunteers using a support vector machine (SVM. The use of a training set that was 50

  17. Music performance anxiety in skilled pianists: effects of social-evaluative performance situation on subjective, autonomic, and electromyographic reactions.

    Science.gov (United States)

    Yoshie, Michiko; Kudo, Kazutoshi; Murakoshi, Takayuki; Ohtsuki, Tatsuyuki

    2009-11-01

    Music performance anxiety (MPA), or stage fright in music performance, is a serious problem for many musicians, because performance impairment accompanied by MPA can threaten their career. The present study sought to clarify on how a social-evaluative performance situation affects subjective, autonomic, and motor stress responses in pianists. Measurements of subjective state anxiety, heart rate (HR), sweat rate (SR), and electromyographic (EMG) activity of upper extremity muscles were obtained while 18 skilled pianists performed a solo piano piece(s) of their choice under stressful (competition) and non-stressful (rehearsal) conditions. Participants reported greater anxiety in the competition condition, which confirmed the effectiveness of stress manipulation. The HR and SR considerably increased from the rehearsal to competition condition reflecting the activation of sympathetic division of the autonomic nervous system. Furthermore, participants showed higher levels of the EMG magnitude of proximal muscles (biceps brachii and upper trapezius) and the co-contraction of antagonistic muscles in the forearm (extensor digitorum communis and flexor digitorum superficialis) in the competition condition. Although these responses can be interpreted as integral components of an adaptive biological system that creates a state of motor readiness in an unstable or unpredictable environment, they can adversely influence pianists by disrupting their fine motor control on stage and by increasing the risk of playing-related musculoskeletal disorders.

  18. Effect of a Bluetooth-implemented hearing aid on speech recognition performance: subjective and objective measurement.

    Science.gov (United States)

    Kim, Min-Beom; Chung, Won-Ho; Choi, Jeesun; Hong, Sung Hwa; Cho, Yang-Sun; Park, Gyuseok; Lee, Sangmin

    2014-06-01

    The object was to evaluate speech perception improvement through Bluetooth-implemented hearing aids in hearing-impaired adults. Thirty subjects with bilateral symmetric moderate sensorineural hearing loss participated in this study. A Bluetooth-implemented hearing aid was fitted unilaterally in all study subjects. Objective speech recognition score and subjective satisfaction were measured with a Bluetooth-implemented hearing aid to replace the acoustic connection from either a cellular phone or a loudspeaker system. In each system, participants were assigned to 4 conditions: wireless speech signal transmission into hearing aid (wireless mode) in quiet or noisy environment and conventional speech signal transmission using external microphone of hearing aid (conventional mode) in quiet or noisy environment. Also, participants completed questionnaires to investigate subjective satisfaction. Both cellular phone and loudspeaker system situation, participants showed improvements in sentence and word recognition scores with wireless mode compared to conventional mode in both quiet and noise conditions (P Bluetooth-implemented hearing aids helped to improve subjective and objective speech recognition performances in quiet and noisy environments during the use of electronic audio devices.

  19. Conformal grasping using feedback controlled bubble actuator array

    Science.gov (United States)

    Carrigan, Wei; Stein, Richard; Mittal, Manoj; Wijesundara, Muthu B. J.

    2014-06-01

    This paper presents an implementation of a bubble actuator array (BAA) based active robotic skin, a modular system, onto existing low cost robotic end-effectors or prosthetic hands for conformal grasping of objects. The active skin is comprised of pneumatically controlled polyurethane rubber bubbles with overlaid sensors for feedback control. Sensor feedback allows the BAA based robotic skin to conformally grasp an object with an explicit uniform force distribution. The bubble actuator array reported here is capable of applying up to 4N of force at each point of contact and tested for conformally grasping objects with a radius of curvature up to 57.15mm. Once integrated onto a two-finger gripper with one degree of freedom (DOF), the active skin was shown to reduce point of contact forces of up to 50% for grasped objects.

  20. The contributions of vision and haptics to reaching and grasping

    Directory of Open Access Journals (Sweden)

    Kayla Dawn Stone

    2015-09-01

    Full Text Available This review aims to provide a comprehensive outlook on the sensory (visual and haptic contributions to reaching and grasping. The focus is on studies in developing children, normal and neuropsychological populations, and in sensory-deprived individuals. Studies have suggested a right-hand/left-hemisphere specialization for visually-guided grasping and a left-hand/right-hemisphere specialization for haptically-guided object recognition. This poses the interesting possibility that when vision is not available and grasping relies heavily on the haptic system, there is an advantage to use the left hand. We review the evidence for this possibility and dissect the unique contributions of the visual and haptic systems to grasping. We ultimately discuss how the integration of these two sensory modalities shape hand preference.

  1. The relationship between wrist position, grasp size, and grip strength.

    Science.gov (United States)

    O'Driscoll, S W; Horii, E; Ness, R; Cahalan, T D; Richards, R R; An, K N

    1992-01-01

    In the first part of this study, the position assumed by a normal wrist during unconstrained maximal grip and the relationship between wrist position and grip strength were investigated in 20 healthy subjects. Grip strength and wrist position were recorded in the self-selected position and then again while the subjects voluntarily deviated the wrist randomly into flexion, extension, or radial or ulnar deviation of 10 to 15 degrees. The self-selected position was 35 degrees of extension and 7 degrees of ulnar deviation. Grip strength was significantly less in any position of deviation from this self-selected position, even after accounting for fatigue. With the wrist in only 15 degrees of extension or in neutral radio-ulnar deviation, grip strength was reduced to two thirds to three fourths of normal. Sex did not affect wrist position. The dominant wrists were within 5 degrees of the nondominant ones but were relatively less extended and in more ulnar deviation. Grip strength is significantly reduced when wrist position deviates from this self-selected optimum position. In the second part of the study, the effect of grasp size on this self-selected position was studied in 21 subjects. The degree of wrist extension was inversely and linearly related to how large a setting on the Jamar dynamometer was used. This was true regardless of hand size, although the effect was more significant for smaller hands. Radial and ulnar deviations were not affected by handle position. A minimum of 25 degrees of wrist extension was required for optimum grip strength.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. A mathematical model for grasping analysis of flexible materials

    Science.gov (United States)

    Lin, Hua; Taylor, Paul M.; Bull, Steve J.

    2005-03-01

    The issue of grasping is fundamental as part of handling routines. Many gripping devices have been proposed and invented for flexible material handling, but a mathematical understanding of the relationship between the parameters of gripper and the properties of object to be grasped has not been obtained completely. With this, it is unrealistic to expect to develop a flexible grasping system—an intelligent grasping system. In this paper, a mathematical model for analysis of flexible materials pressed by a curved surface pinch gripper using the elasticity theory is presented. The relationship between an indenter, an external load and the properties of the material being handled is established. The distributions of stress and displacement within a sample have been derived. The contact interface between the indenter and the sample is solved with the aid of the Hertz elastic contact equations. A solution for calculating the contact length between a sample and a rigid table is developed. In order to model experimental behaviour the non-linear elastic response of the material and large deformations have to be incorporated in the model. Thus, this model provides a complete system for solving the problem of a small indenter pressing a flexible specimen of a much larger size. The predictions of the model are tested against experimental data and the results of finite element analysis, and reasonably good agreement is obtained. It is expected that the intelligent grasping system can adjust its grasping force systematically based on this model by adapting to the properties of the material to be grasped, and this should be of benefit for both grasping analysis and gripper design.

  3. The efficacy of objective and subjective predictors of driving performance during sleep restriction and circadian misalignment.

    Science.gov (United States)

    Kosmadopoulos, Anastasi; Sargent, Charli; Zhou, Xuan; Darwent, David; Matthews, Raymond W; Dawson, Drew; Roach, Gregory D

    2017-02-01

    Fatigue is a significant contributor to motor-vehicle accidents and fatalities. Shift workers are particularly susceptible to fatigue-related risks as they are often sleep-restricted and required to commute around the clock. Simple assays of performance could provide useful indications of risk in fatigue management, but their effectiveness may be influenced by changes in their sensitivity to sleep loss across the day. The aim of this study was to evaluate the sensitivity of several neurobehavioral and subjective tasks to sleep restriction (SR) at different circadian phases and their efficacy as predictors of performance during a simulated driving task. Thirty-two volunteers (M±SD; 22.8±2.9 years) were time-isolated for 13-days and participated in one of two 14-h forced desynchrony protocols with sleep opportunities equivalent to 8h/24h (control) or 4h/24h (SR). At regular intervals during wake periods, participants completed a simulated driving task, several neurobehavioral tasks, including the psychomotor vigilance task (PVT), and subjective ratings, including a self-assessment measure of ability to perform. Scores transformed into standardized units relative to baseline were folded into circadian phase bins based on core body temperature. Sleep dose and circadian phase effect sizes were derived via mixed models analyses. Predictors of driving were identified with regressions. Performance was most sensitive to sleep restriction around the circadian nadir. The effects of sleep restriction around the circadian nadir were larger for simulated driving and neurobehavioral tasks than for subjective ratings. Tasks did not significantly predict driving performance during the control condition or around the acrophase during the SR condition. The PVT and self-assessed ability were the best predictors of simulated driving across circadian phases during SR. These results show that simple performance measures and self-monitoring explain a large proportion of the variance in

  4. Effect of tone-based sound stimulation on balance performance of normal subjects: preliminary investigation.

    Science.gov (United States)

    Pagnacco, Guido; Klotzek, Adam S; Carrick, Frederick R; Wright, Cameron H G; Oggero, Elena

    2015-01-01

    Sound is known to affect the human brain, hence sound or music therapy is sometimes used to improve a subject's physicaland mental health. In this study, the effects sound stimulation has on balance were investigated by means of computerizeddynamic posturography tests performed with eyes closed on an unstable surface using a CAPS® system, exceeding theInternational Society for Posture and Gait Research (ISPGR) recommended metrological performance standards. Subjectswere tested without listening to any music (baseline), listening to “pure music”, and listening to the same music with differenttones embedded into it (one for each key). We found that different subjects react differently to different tones. Music alonedid not have a statistically significant effect on balance compared to the baseline, but the “best” tone significantly improvedbalance compared to the baseline or the “pure music” conditions. Furthermore, the “worst” tone reduced the balancecompared to “pure music”, but the reduction was not statistically significant relative to the baseline. The results thereforeindicate that, at least relative to balance performance, the tone-based sound stimulation we investigated is effective andinherently safe, but that tone selection depends on the individual subject.

  5. Bioinspired locomotion and grasping in water: the soft eight-arm OCTOPUS robot.

    Science.gov (United States)

    Cianchetti, M; Calisti, M; Margheri, L; Kuba, M; Laschi, C

    2015-05-13

    The octopus is an interesting model for the development of soft robotics, due to its high deformability, dexterity and rich behavioural repertoire. To investigate the principles of octopus dexterity, we designed an eight-arm soft robot and evaluated its performance with focused experiments. The OCTOPUS robot presented here is a completely soft robot, which integrates eight arms extending in radial direction and a central body which contains the main processing units. The front arms are mainly used for elongation and grasping, while the others are mainly used for locomotion. The robotic octopus works in water and its buoyancy is close to neutral. The experimental results show that the octopus-inspired robot can walk in water using the same strategy as the animal model, with good performance over different surfaces, including walking through physical constraints. It can grasp objects of different sizes and shapes, thanks to its soft arm materials and conical shape.

  6. Effects of Background Music on Objective and Subjective Performance Measures in an Auditory BCI.

    Science.gov (United States)

    Zhou, Sijie; Allison, Brendan Z; Kübler, Andrea; Cichocki, Andrzej; Wang, Xingyu; Jin, Jing

    2016-01-01

    Several studies have explored brain computer interface (BCI) systems based on auditory stimuli, which could help patients with visual impairments. Usability and user satisfaction are important considerations in any BCI. Although background music can influence emotion and performance in other task environments, and many users may wish to listen to music while using a BCI, auditory, and other BCIs are typically studied without background music. Some work has explored the possibility of using polyphonic music in auditory BCI systems. However, this approach requires users with good musical skills, and has not been explored in online experiments. Our hypothesis was that an auditory BCI with background music would be preferred by subjects over a similar BCI without background music, without any difference in BCI performance. We introduce a simple paradigm (which does not require musical skill) using percussion instrument sound stimuli and background music, and evaluated it in both offline and online experiments. The result showed that subjects preferred the auditory BCI with background music. Different performance measures did not reveal any significant performance effect when comparing background music vs. no background. Since the addition of background music does not impair BCI performance but is preferred by users, auditory (and perhaps other) BCIs should consider including it. Our study also indicates that auditory BCIs can be effective even if the auditory channel is simultaneously otherwise engaged.

  7. Effects of background music on objective and subjective performance measures in an auditory BCI

    Directory of Open Access Journals (Sweden)

    Sijie Zhou

    2016-10-01

    Full Text Available Several studies have explored brain computer interface (BCI systems based on auditory stimuli, which could help patients with visual impairments. Usability and user satisfaction are important considerations in any BCI. Although background music can influence emotion and performance in other task environments, and many users may wish to listen to music while using a BCI, auditory and other BCIs are typically studied without background music. Some work has explored the possibility of using polyphonic music in auditory BCI systems. However, this approach requires users with good musical skills, and has not been explored in online experiments. Our hypothesis was that an auditory BCI with background music would be preferred by subjects over a similar BCI without background music, without any difference in BCI performance. We introduce a simple paradigm (which does not require musical skill using percussion instrument sound stimuli and background music, and evaluated it in both offline and online experiments. The result showed that subjects preferred the auditory BCI with background music. Different performance measures did not reveal any significant performance effect when comparing background music vs. no background. Since the addition of background music does not impair BCI performance but is preferred by users, auditory (and perhaps other BCIs should consider including it. Our study also indicates that auditory BCIs can be effective even if the auditory channel is simultaneously otherwise engaged.

  8. Preserving Subject Variability in Group fMRI Analysis: Performance Evaluation of GICA versus IVA

    Directory of Open Access Journals (Sweden)

    Andrew eMichael

    2014-06-01

    Full Text Available Independent component analysis (ICA is a widely applied technique to derive functionally connected brain networks from fMRI data. Group ICA (GICA and Independent Vector Analysis (IVA are extensions of ICA that enable users to perform group fMRI analyses; however a full comparison of the performance limits of GICA and IVA has not been investigated. Recent interest in resting state fMRI data with potentially higher degree of subject variability makes the evaluation of the above techniques important. In this paper we compare component estimation accuracies of GICA and an improved version of IVA using simulated fMRI datasets. We systematically change the degree of component spatial variability and evaluate estimation accuracy over all spatial maps (SMs and time courses (TCs of the decomposition. Our results indicate the following: (1 at low levels of SM variability or when just one SM is varied, both GICA and IVA perform well, (2 at higher levels of SM variability or when more than one SMs are varied, IVA continues to perform well but GICA yields SM estimates that are composites of other SMs with errors in TCs, (3 both GICA and IVA remove spatial correlations of overlapping SMs and introduce artificial correlations in their TCs, (4 if number of SMs is over estimated, IVA continues to perform well but GICA introduces artifacts in the varying and extra SMs with artificial correlations in the TCs of extra components, and (5 in the absence or presence of SMs unique to one subject, GICA produces errors in TCs and IVA estimates are accurate. In summary, our simulation experiments (both simplistic and realistic and our holistic analyses approach indicate that IVA produces results that are closer to ground truth and thereby better preserves subject variability. The improved version of IVA is now packaged into the GIFT toolbox (http://mialab.mrn.org/software/gift.

  9. Grasping force hysteresis compensation of a piezoelectric-actuated wire clamp with a modified inverse Prandtl-Ishlinskii model

    Science.gov (United States)

    Liang, Cunman; Wang, Fujun; Tian, Yanling; Zhao, Xingyu; Zhang, Dawei

    2017-11-01

    This paper presents the grasping force hysteresis compensation of a piezoelectric-actuated wire clamp with a modified hysteresis model. Considering dynamic characteristics of the wire clamp, a modified inverse Prandtl-Ishlinskii (MIPI) hysteresis model is developed to improve the hysteresis modeling accuracy. The proposed MIPI model is composed of a P-I model and a dynamic model which are connected in parallel. The proposed hysteresis model has the advantage of high modeling accuracy with a concise identification process, which means the step by step identification is not needed here. Experiments on grasping force hysteresis compensation with a feedforward controller are carried out based on the developed MIPI model. The grasping force error in steady state lies in ±8.17 mN, while the maximum percentage and root mean square percentage of the grasping force error are 2.93% and 0.92%, respectively. The results show that the proposed hysteresis model is efficient and the wire clamp exhibits good performance with the feedforward controller. Therefore high frequency grasping operations can be realized based on the proposed MIPI hysteresis model.

  10. Effect of oral dietary supplement for chicks subjected to thermal oscillation on performance and intestinal morphometry

    Directory of Open Access Journals (Sweden)

    Jovanir Inês Müller Fernandes

    2017-09-01

    Full Text Available The aim of the study was to evaluate the efficacy of a nutritional formulation based on amino acids and vitamins supplemented in the drinking water for chicks in the first week of life subjected to thermal oscillation on performance, organ development and intestinal morphometry from 1 to 21 days. 640-male broiler chicks were distributed in a 2x2 factorial completely randomized design (with or without dietary supplementation and at comfort temperature or thermal oscillation. Chicks subjected to thermal oscillation presented worse performance (p < 0.05 than those under thermal comfort of 1 to 7, 1 to 14 and 1 to 21 days. Nutritional supplementation did not alter the performance (p < 0.05 of the birds, but resulted in a higher body weight (p < 0.05 regardless of the environmental thermal condition. At 7 days, chicks under thermal comfort had better intestinal morphometric parameters (p < 0.05, in relation to birds under thermal oscillation. In conclusion, the temperature oscillations caused negative consequences to the productive performance and the intestinal morphology of chicks for which dietary supplementation was not enough to mitigate the effects of the environmental challenge during the first week of life of the birds.

  11. Tracking Systems for Virtual Rehabilitation: Objective Performance vs. Subjective Experience. A Practical Scenario

    Directory of Open Access Journals (Sweden)

    Roberto Lloréns

    2015-03-01

    Full Text Available Motion tracking systems are commonly used in virtual reality-based interventions to detect movements in the real world and transfer them to the virtual environment. There are different tracking solutions based on different physical principles, which mainly define their performance parameters. However, special requirements have to be considered for rehabilitation purposes. This paper studies and compares the accuracy and jitter of three tracking solutions (optical, electromagnetic, and skeleton tracking in a practical scenario and analyzes the subjective perceptions of 19 healthy subjects, 22 stroke survivors, and 14 physical therapists. The optical tracking system provided the best accuracy (1.074 ± 0.417 cm while the electromagnetic device provided the most inaccurate results (11.027 ± 2.364 cm. However, this tracking solution provided the best jitter values (0.324 ± 0.093 cm, in contrast to the skeleton tracking, which had the worst results (1.522 ± 0.858 cm. Healthy individuals and professionals preferred the skeleton tracking solution rather than the optical and electromagnetic solution (in that order. Individuals with stroke chose the optical solution over the other options. Our results show that subjective perceptions and preferences are far from being constant among different populations, thus suggesting that these considerations, together with the performance parameters, should be also taken into account when designing a rehabilitation system.

  12. Evaluation of Pressure Capacitive Sensors for Application in Grasping and Manipulation Analysis

    Directory of Open Access Journals (Sweden)

    Paola Pessia

    2017-12-01

    Full Text Available The analysis of the human grasping and manipulation capabilities is paramount for investigating human sensory-motor control and developing prosthetic and robotic hands resembling the human ones. A viable solution to perform this analysis is to develop instrumented objects measuring the interaction forces with the hand. In this context, the performance of the sensors embedded in the objects is crucial. This paper focuses on the experimental characterization of a class of capacitive pressure sensors suitable for biomechanical analysis. The analysis was performed in three loading conditions (Distributed load, 9 Tips load, and Wave-shaped load, thanks to three different inter-elements via a traction/compression testing machine. Sensor assessment was also carried out under human- like grasping condition by placing a silicon material with the same properties of prosthetic cosmetic gloves in between the sensor and the inter-element in order to simulate the human skin. Data show that the input–output relationship of the analyzed, sensor is strongly influenced by both the loading condition (i.e., type of inter-element and the grasping condition (with or without the silicon material. This needs to be taken into account to avoid significant measurement error. To go over this hurdle, the sensors have to be calibrated under each specific condition in order to apply suitable corrections to the sensor output and significantly improve the measurement accuracy.

  13. Evaluation of Pressure Capacitive Sensors for Application in Grasping and Manipulation Analysis.

    Science.gov (United States)

    Pessia, Paola; Cordella, Francesca; Schena, Emiliano; Davalli, Angelo; Sacchetti, Rinaldo; Zollo, Loredana

    2017-12-08

    The analysis of the human grasping and manipulation capabilities is paramount for investigating human sensory-motor control and developing prosthetic and robotic hands resembling the human ones. A viable solution to perform this analysis is to develop instrumented objects measuring the interaction forces with the hand. In this context, the performance of the sensors embedded in the objects is crucial. This paper focuses on the experimental characterization of a class of capacitive pressure sensors suitable for biomechanical analysis. The analysis was performed in three loading conditions (Distributed load, 9 Tips load, and Wave-shaped load, thanks to three different inter-elements) via a traction/compression testing machine. Sensor assessment was also carried out under human- like grasping condition by placing a silicon material with the same properties of prosthetic cosmetic gloves in between the sensor and the inter-element in order to simulate the human skin. Data show that the input-output relationship of the analyzed, sensor is strongly influenced by both the loading condition (i.e., type of inter-element) and the grasping condition (with or without the silicon material). This needs to be taken into account to avoid significant measurement error. To go over this hurdle, the sensors have to be calibrated under each specific condition in order to apply suitable corrections to the sensor output and significantly improve the measurement accuracy.

  14. Intra-Subject Variability of 5 Km Time Trial Performance Completed by Competitive Trained Runners

    Directory of Open Access Journals (Sweden)

    Fisher James

    2017-06-01

    Full Text Available Time-trials represent an ecologically valid approach to assessment of endurance performance. Such information is useful in the application of testing protocols and estimation of sample sizes required for research/magnitude based inference methods. The present study aimed to investigate the intra-subject variability of 5 km time-trial running performance in trained runners. Six competitive trained male runners (age = 33.8 ± 10.1 years; stature = 1.78 ± 0.01 m; body mass = 69.0 ± 10.4 kg, V. $\\it V^{.}$ O2max = 62.6 ± 11.0 ml·kg·min-1 completed an incremental exercise test to volitional exhaustion followed by 5 x 5 km time-trials (including a familiarisation trial, individually spaced by 48 hours. The time taken to complete each trial, heart rate, rating of perceived exertion and speed were all assessed. Intra-subject absolute standard error of measurement and the coefficient of variance were calculated for time-trial variables in addition to the intra-class correlation coefficient for time taken to complete the time-trial. For the primary measure time, results showed a coefficient of variation score across all participants of 1.5 ± 0.59% with an intra-class correlation coefficient score of 0.990. Heart rate, rating of perceived exertion and speed data showed a variance range between 0.8 and 3.05%. It was concluded that when compared with related research, there was observed low intra-subject variability in trained runners over a 5 km distance. This supports the use of this protocol for 5 km time-trial performance for assessment of nutritional strategies, ergogenic aids or training interventions on endurance running performance.

  15. The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers

    Directory of Open Access Journals (Sweden)

    Makoto eBannai

    2012-04-01

    Full Text Available Approximately 30% of the general population suffers from insomnia. Given that insomnia causes many problems, amelioration of the symptoms is crucial. Recently, we found that a nonessential amino acid, glycine subjectively and objectively improves sleep quality in humans who have difficulty sleeping. We evaluated the effects of glycine on daytime sleepiness, fatigue and performances in sleep-restricted healthy subjects. Sleep was restricted to 25% less than the usual sleep time for three consecutive nights. Before bedtime, 3 g of glycine or placebo were ingested, sleepiness and fatigue were evaluated using the visual analogue scale (VAS and a questionnaire, and performance were estimated by personal computer (PC performance test program on the following day. In subjects given glycine, the VAS data showed a significant reduction in fatigue and a tendency toward reduced sleepiness. These observations were also found via the questionnaire, indicating that glycine improves daytime sleepiness and fatigue induced by acute sleep restriction. PC performance test revealed significant improvement in psychomotor vigilance test. We also measured plasma melatonin and the expression of circadian-modulated genes expression in the rat suprachiasmatic nucleus (SCN to evaluate the effects of glycine on circadian rhythms. Glycine did not show significant effects on plasma melatonin concentrations during either the dark or light period. Moreover, the expression levels of clock genes such as Bmal1 and Per2 remained unchanged. However, we observed a glycine-induced increase in the neuropeptides arginine vasopressin and vasoactive intestinal polypeptide in the light period. Although no alterations in the circadian clock itself were observed, our results indicate that glycine modulated SCN function. Thus, glycine modulates certain neuropeptides in the SCN and this phenomenon may indirectly contribute to improving the occasional sleepiness and fatigue induced by sleep

  16. Reliability and validity of videotaped functional performance tests in ACL-injured subjects

    DEFF Research Database (Denmark)

    von Porat, Anette; Holmström, Eva; Roos, Ewa

    2008-01-01

    during five functional tests in subjects with an anterior cruciate ligament (ACL) injury. METHOD: Twelve ACL-injured men, mean age 40 years, were video filmed before and after 12 weeks of knee-specific training when performing five different functional tests: walking, knee bending, step activity......, crossover hop on one leg and one-leg hop. The videos were observed by four physiotherapists, and the knee movement pattern quality, a feature of the loading strategy of the lower extremity, was scored on an 11-point rating scale. To assess the criterion validity, the observational rating was correlated...... validity found indicate that the knee movement pattern quality in ACL-injured subjects can be determined by visual observation of more demanding functional tests such as crossover hop on one leg and one-leg hop for distance....

  17. Pilot study of light therapy and neurocognitive performance of attention and memory in healthy subjects.

    Science.gov (United States)

    Bersani, Giuseppe; Marconi, Daniela; Limpido, Lucilla; Tarolla, Emanuele; Caroti, Eleonora

    2008-02-01

    The aim of this pilot study was to investigate whether light therapy improves healthy subjects' neurocognitive performance of attention, memory, and language. Ten subjects were treated with white bright light for 5 days and a control group of 10 with no treatment were assessed with a battery of neurocognitive tests which included the Stroop Colour Word Interference Test, the Verbal Fluency Test, the Story Recall Test, and the Word Pairs Recall Test. Analysis showed improvements in cognitive scores in both groups, although on all the cognitive tests the mean difference scores between baseline and endpoint were significantly larger in the light-treated group. These preliminary results suggest that short-term bright light may exert beneficial effects on cognitive functions.

  18. A Comparative Study of the Empirical Relationship in Student Performance between Physics and Other STEM Subjects

    Science.gov (United States)

    Guerra, Maricela

    The Next Generation Science Standards (NGSS) advocated by the National Research Council emphasize the connections among Science, Technology, Engineering, and Mathematics (STEM) disciplines. By design, NGSS is expected to replace the previous science education standards to enhance the quality of STEM education across the nation. To support this initiative, this investigation was conducted to fill a void in the research literature by developing an empirical indicator for the relationship of student performance across STEM subjects using a large-scale database from the Trends in Mathematics and Science Study (TIMSS). In particular, an innovative approach has been taken in this study to support the canonical correlation analysis of student plausible scores between physics and other STEM subjects at different grade levels and in a cross-country context. Results from this doctoral research revealed the need to strengthen the alignment between the intended, implemented, and attained curricula to support the integration of STEM disciplines in the United States.

  19. Scheduling trucks in cross docking systems with temporary storage and dock repeat truck holding pattern using GRASP method

    Directory of Open Access Journals (Sweden)

    Hassan Javanshir

    2012-10-01

    Full Text Available Cross docking play an important role in management of supply chains where items delivered to a warehouse by inbound trucks are directly sorted out, reorganized based on customer demands, routed and loaded into outbound trucks for delivery to customers without virtually keeping them at the warehouse. If any item is held in storage, it is usually for a short time, which is normally less than 24 hours. The proposed model of this paper considers a special case of cross docking where there is temporary storage and uses GRASP technique to solve the resulted problem for some realistic test problems. In our method, we first use some heuristics as initial solutions and then improve the final solution using GRASP method. The preliminary test results indicate that the GRASP method performs better than alternative solution strategies.

  20. A rough concrete wall-climbing robot based on grasping claws

    Directory of Open Access Journals (Sweden)

    Fengyu Xu

    2016-10-01

    Full Text Available Climbing robots have been widely used to inspect smooth walls. However, a good adsorption method has not been found for the inspection of a cliff surface and a dusty high-altitude surface with small vibration, both of which are made of coarse concrete, square brick, or rock. In this article, first, we analyzed the bionic structure of the cockroach legs and observed their morphological characteristics of the spiny claws on these legs. We also studied the interaction theory of the bionic claw with the bulges on the rough wall surfaces and deduced the mechanical criteria of the claws grabbing steadily these bulges. Then, an initial mechanical structure of a wall-climbing robot was proposed based on a grasping claw and a climbing model. Furthermore, a mathematical model was established to reflect the relationship between sharp hooks and bulges on the rough wall. Finally, we performed several laboratory experiments to verify the grasping stability.

  1. Keeping Safe: Intra-individual Consistency in Obstacle Avoidance Behaviour Across Grasping and Locomotion Tasks.

    Science.gov (United States)

    Kangur, Karina; Billino, Jutta; Hesse, Constanze

    2017-01-01

    Successful obstacle avoidance requires a close coordination of the visual and the motor systems. Visual information is essential for adjusting movements in order to avoid unwanted collisions. Yet, established obstacle avoidance paradigms have typically either focused on gaze strategies or on motor adjustments. Here we were interested in whether humans show similar visuomotor sensitivity to obstacles when gaze and motor behaviour are measured across different obstacle avoidance tasks. To this end, we measured participants' hand movement paths when grasping targets in the presence of obstacles as well as their gaze behaviour when walking through a cluttered hallway. We found that participants who showed more pronounced motor adjustments during grasping also spent more time looking at obstacles during locomotion. Furthermore, movement durations correlated positively in both tasks. Results suggest considerable intra-individual consistency in the strength of the avoidance response across different visuomotor measures potentially indicating an individual's tendency to perform safe actions.

  2. School-performance indicators and subjective health complaints: are there gender differences?

    Science.gov (United States)

    Brolin Låftman, Sara; Modin, Bitte

    2012-05-01

    Although boys and girls are generally located in the same physical school environment, it may be experienced differently by, and have varying implications for, boys and girls. Girls like school more and achieve higher school marks, but they also perceive more school-related pressure. Based on a total sample of 8456 ninth grade pupils in Stockholm in 2004, this study uses multilevel linear regression to analyse differences between boys and girls with regard to a number of school-performance indicators (demands, motivation, teacher support and school marks) and their association with subjective health complaints. Results showed that girls perceive more demands, show greater academic motivation, perform better in school and report more emotional support from teachers than boys. In contrast, instrumental and appraisal support from teachers are more commonly reported by boys. Associations between school-performance indicators and subjective health complaints were slightly stronger for girls than for boys. Contextual variation in health complaints, especially between classes, was found only for girls. High achievement motivation and emotional teacher support in the school class was associated with better pupil health, suggesting that a positive climate in terms of motivation and support favours class health as a whole. © 2011 The Authors. Sociology of Health & Illness © 2011 Foundation for the Sociology of Health & Illness/Blackwell Publishing Ltd.

  3. Performance Testing of Lidar Components Subjected to Space Exposure in Space via MISSE 7 Mission

    Science.gov (United States)

    Prasad, Narasimha S.

    2012-01-01

    .The objective of the Materials International Space Station Experiment (MISSE) is to study the performance of novel materials when subjected to the synergistic effects of the harsh space environment for several months. MISSE missions provide an opportunity for developing space qualifiable materials. Several laser and lidar components were sent by NASA Langley Research Center (LaRC) as a part of the MISSE 7 mission. The MISSE 7 module was transported to the international space station (ISS) via STS 129 mission that was launched on Nov 16, 2009. Later, the MISSE 7 module was brought back to the earth via the STS 134 that landed on June 1, 2011. The MISSE 7 module that was subjected to exposure in space environment for more than one and a half year included fiber laser, solid-state laser gain materials, detectors, and semiconductor laser diode. Performance testing of these components is now progressing. In this paper, the current progress on post-flight performance testing of a high-speed photodetector and a balanced receiver is discussed. Preliminary findings show that detector characteristics did not undergo any significant degradation.

  4. Effects of habitual variations in napping on psychomotor performance, memory and subjective states.

    Science.gov (United States)

    Taub, J M

    1979-01-01

    Effects of habitual variations in napping on psychomotor performance, short-term memory and subjective states were investigated. The subjects were 32 healthy male university students who napped twice or more weekly in themorning and at night. Sixteen were randomly assigned to a control group and 16 to a nap(treatment) group. The experiment comprised two conditions of electrographically (EEG) recorded sleep for the nap group and two EEG monitored conditions of wakefulness for the controls. These conditions were scheduled from 9:35 to 11:35 a.m. and 12 hr later between 9:35 p.m. and 11:35 p.m. Measurements were obtained from: (a) a continuous 10-min auditory reaction time task, (b) a free recall task of short-term memory, (c) an activation-mood adjective check list, and (d) the Stanford Sleepiness scale. Except for memory the dependent variables of waking function were assessed 20 min before and 20 min after all conditions. Following each sleep condition the nap group as opposed to the controls showed a statistically significant improvement in reaction time performance, higher short-term retention, less reported sleepiness and elevated subjective states reflected by fice factors on the adjective mood-activation check list. Among the correlations computed the largest significant coefficients were of stage 4 and REM with posttreatment Stanford Sleepiness ratings. After naps, increased postdormital sleepiness was correlated with stage 4 and decreased sleepiness with REM sleep. Although few strikingly divergent functional effects were associated with morning and nocturanal naps, these did covary with sleep psychophysiology. It is postulated that the phase, the EEG-sleep stages and possibly the duration of accustomed naps are less salient factors influencing performance when the time since awakening until behavioral assessment can be kept constant.

  5. Subjective experiences of occupational performance of activities of daily living in patients with mild stroke

    DEFF Research Database (Denmark)

    Kristensen, Hanne Kaae; Postat, Annemette; Poulsen, Trine

    2014-01-01

    and risk of accidents. Conclusion: It is important to view the patients with mild stroke as heterogeneous, and consider post-stroke fatigue and emotional reactions when evaluating rehabilitation needs. Therefore, it is important to look further into structured tools, which examine how well the participant......Aim: To investigate the subjective experiences of occupational performance of activities of daily living (ADL) in patients with mild stroke. Methodology: Data was generated from January – December 2011 and consisted of 41 individual ADL-I interviews with patients in hospital and another 41...

  6. Effects of Sleep Hygiene Education on Subjective Sleep Quality and Academic Performance

    Directory of Open Access Journals (Sweden)

    Erkan Sahin

    2014-12-01

    Full Text Available Aim: Sleep problems are common in students with one third of university students reporting insufficient sleep. It is known that sleep quality and daytime sleepiness cause decrasing academic performans. For this reason we aimed to investigate the effects of a sleep hygiene education on sleep quality and academic performance of first year medical students. Material and Method: Self-reported sleep data and academic performance of 131 first grade medical students were collected. To all students enrolled Pittsburg Sleep Quality Scale in the assessment of sleep quality and Epworth Sleepiness Scale for assessment of daytime sleepiness in the evaluation.The students were divided into two subgroups and the intervention group received a 30 minute structured sleep hygiene education. Global academic performance was assessed by grade point average at the end of the year. Results: Mean Pittsburgh sleep quality index score of the students was 7.9±3.5 and 106 (82.8% of then had a score %u22655.After intervention, .the worse the initial sleep quality, the more improvement by the sleep hygiene education on sleep quality and academic performance. Discussion: An education on sleep hygiene might improve subjective sleep quality and academic performance of medical students.

  7. Systematic Influence of Perceived Grasp Shape on Speech Production.

    Science.gov (United States)

    Vainio, Lari; Rantala, Aleksi; Tiainen, Mikko; Tiippana, Kaisa; Komeilipoor, Naeem; Vainio, Martti

    2017-01-01

    Previous research has shown that precision and power grip performance is consistently influenced by simultaneous articulation. For example, power grip responses are performed relatively fast with the open-back vowel [a], whereas precision grip responses are performed relatively fast with the close-front vowel [i]. In the present study, the participants were presented with a picture of a hand shaped to the precision or power grip. They were required to pronounce speech sounds according to the front/above perspective of the hand. The results showed that not only the grip performance is affected by simultaneously pronouncing the speech sound but also the production of speech sound can be affected by viewing an image of a grip. The precision grip stimulus triggered relatively rapid production of the front-close vowel [i]. In contrast, the effect related to the power grip stimulus was mostly linked to the vertical dimension of the pronounced vowel since this stimulus triggered relatively rapid production of the back-open vowel [a] and back-mid-open vowel [o] while production of the back-close vowel [u] was not influenced by it. The fact that production of the dorsal consonant [k] or coronal consonant [t] were not influenced by these stimuli suggests that the effect was not associated with a relative front-back tongue shape of the articulation in the absence of changes in any vertical articulatory components. These findings provide evidence for an intimate interaction between certain articulatory gestures and grip types, suggesting that an overlapping visuomotor network operates for planning articulatory gestures and grasp actions.

  8. Toward autonomous avian-inspired grasping for micro aerial vehicles.

    Science.gov (United States)

    Thomas, Justin; Loianno, Giuseppe; Polin, Joseph; Sreenath, Koushil; Kumar, Vijay

    2014-06-01

    Micro aerial vehicles, particularly quadrotors, have been used in a wide range of applications. However, the literature on aerial manipulation and grasping is limited and the work is based on quasi-static models. In this paper, we draw inspiration from agile, fast-moving birds such as raptors, that are able to capture moving prey on the ground or in water, and develop similar capabilities for quadrotors. We address dynamic grasping, an approach to prehensile grasping in which the dynamics of the robot and its gripper are significant and must be explicitly modeled and controlled for successful execution. Dynamic grasping is relevant for fast pick-and-place operations, transportation and delivery of objects, and placing or retrieving sensors. We show how this capability can be realized (a) using a motion capture system and (b) without external sensors relying only on onboard sensors. In both cases we describe the dynamic model, and trajectory planning and control algorithms. In particular, we present a methodology for flying and grasping a cylindrical object using feedback from a monocular camera and an inertial measurement unit onboard the aerial robot. This is accomplished by mapping the dynamics of the quadrotor to a level virtual image plane, which in turn enables dynamically-feasible trajectory planning for image features in the image space, and a vision-based controller with guaranteed convergence properties. We also present experimental results obtained with a quadrotor equipped with an articulated gripper to illustrate both approaches.

  9. Alternative computer mouse designs: performance, posture, and subjective evaluations for college students aged 18-25.

    Science.gov (United States)

    Feathers, David J; Rollings, Kimberly; Hedge, Alan

    2013-01-01

    Students are faced with work demands requiring intense computer use throughout the week, often with cumulative hourly use per day exceeding that of adult workers. Extended daily computer use has been associated with a reported increase of musculoskeletal symptoms for college-aged students. New mouse designs offer alternative movement and postural strategies to potentially mitigate musculoskeletal stress for students. This study investigates the use of alternative computer mouse designs by college-aged students (18-25) through a precision task (point-and-click an on-screen target). Wrist movements, hand posture, and associated subjective user data were collected across innovative mouse designs to understand the physical impact and basic usability issues for this population. Twenty-one (21) healthy, right handed students (11 female; 10 male) were enrolled in this study. Five mouse designs were assessed by investigating hand fit, wrist movements, and subjective accounts of ease of use, perceived control, comfort and aesthetics. Human performance was captured for each mouse design in terms of peak velocity, average movement time, and fastest movement direction using an electrogoniometer as participants performed the ISO 9241 multipoint standard Fitts' task using the Generalized Fitts' Law Model Builder software (GFLMB v.1.1C; [1]) within a zero-error setting (point-and-click task). Hand measurements were taken in both standardized anthropometric positions and adapted hand positions on five alternative mouse designs for a total of seven sets of measurements for each participant. Subjective data was collected through a series of questionnaires that were administered before, during, and after the mouse tasks. Results for human performance, distal upper extremity posture (hand/wrist), and subjective data such as overall preference, ease of use, perceived control, and comfort are given for this population. Wrist extension exceeded 30 degrees for over 50% of the total

  10. Objective and subjective visual performance of multifocal contact lenses: pilot study.

    Science.gov (United States)

    Vasudevan, Balamurali; Flores, Michael; Gaib, Sara

    2014-06-01

    The aim of the present study was to compare the objective and subjective visual performance of three different soft multifocal contact lenses. 10 subjects (habitual soft contact lens wearers) between the ages of 40 and 45 years participated in the study. Three different multifocal silicone hydrogel contact lenses (Acuvue Oasys, Air Optix and Biofinity) were fit within the same visit. All the lenses were fit according to the manufacturers' recommendation using the respective fitting guide. Visual performance tests included low and high contrast distance and near visual acuity, contrast sensitivity, range of clear vision and through-focus curve. Objective visual performance tests included measurement of open field accommodative response at different defocus levels and optical aberrations at different viewing distances. Accommodative response was not significantly different between the three types of multifocal contact lenses at each of the accommodative stimulus levels (p>0.05). Accommodative lag increased for higher stimulus levels for all 3 types of contact lenses. Ocular aberrations were not significantly different between these 3 contact lens designs at each of the different viewing distances (p>0.05). In addition, optical aberrations did not significantly differ between different viewing distances for any of these lenses (p>0.05). ANOVA revealed no significant difference in high and low contrast distance visual acuity as well as near visual acuity and contrast sensitivity function between the 3 multifocal contact lenses and spectacles (p>0.05). There was no statistically significant difference in accommodative response, optical aberrations or visual performance between the 3 multifocal contact lenses in early presbyopes. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  11. Performance of Purunã beef calves subjected to different weaning systems

    Directory of Open Access Journals (Sweden)

    Fernando Kuss

    2014-09-01

    Full Text Available The study was developed at Fazenda Modelo an Experimental Station belonged to the Instituto Agronômico do Paraná - IAPAR, in the city of Ponta Grossa, PR, from June to November 2011. The objective was to evaluate the performance of calves subjected to different weaning systems. 161 calves crossbred Purunã were divided into three groups: calves subjected to early weaning (DP, weaned at an average of 75 days old; calves subjected to controlled nursing system (AC with 75 days of age, exposed to suck only once a day during the duration of the breeding season (85 days and; the control group, calves submitted to the system of conventional weaning (DC, were kept together with cow, without interfering in breastfeeding until the end of the breeding season (85 days. Calves fed the DP had lower mean (P<0.05 average daily gain (0.56 kg during the experimental group compared to the AC and DC (0.95 kg and 0.88 kg, respectively which did not differ (P<0.05. Thus, the DP had calves at the end of the breeding season, 32.36 kg and 26.48 kg unless the AC group (167.44 kg and DC (161.56 kg, respectively. The system controlled breastfeeding does not provid damage on the performance of calves at 150 days of age. Already early weaning at 75 days cause decrease of 19.6% in weight of calves at 150 days of age compared to suckler calves.

  12. Effects of Visual Communication Tool and Separable Status Display on Team Performance and Subjective Workload in Air Battle Management

    National Research Council Canada - National Science Library

    Schwartz, Daniel; Knott, Benjamin A; Galster, Scott M

    2008-01-01

    ... ambient cabin noise while performing several visual and manual tasks. The purpose of this study is to compare team performance and subjective workload on a simulated AWACS scenario, for two conditions of communication...

  13. Using subjective judgement to determine the validity of a tutorial performance evaluation instrument

    Directory of Open Access Journals (Sweden)

    Melanie L. Lack

    2009-04-01

    Full Text Available

    Evaluating students’ learning performance is dependent on assessment criteria from which valid inferences can be made about student learning. An existing 36-item instrument used to evaluate baccalaureate nursing students’ performance in problem-based learning tutorials was presented to experts in nursing for their subjective judgement of item validity. Quantitative analysis of data sets from experts’ judgements was used to construct a valid measurement scale for evaluating students’ tutorial performance. The objectives of the study were to determine the content validity of items in a tutorial performance evaluation (TPE instrument and to determine the construct validity of items through paired comparison of main and sub-items in the instrument. Academic experts (n = 8 from two South African universities were selected by means of purposive, maximum variation sampling. Data were collected in three rounds of the Delphi technique, which incorporated the Subjective Judgement Model for paired comparison of instrument items. Experts’ ratings were captured on a visual analogue scale for each item. Relative item weights were determined using
    paired comparisons. Statistical analysis resulted in ratio scale data, each item being assigned a ratio relative to its weight. It was concluded that quantitative analysis of subjective judgements is useful to determine the construct validity of items through paired comparison of items in a TPE instrument. This article presents the methodological perspectives of subjective judgement to establish instrument validity.

    Opsomming

    Die evaluering van studente se leervermoë is afhanklik van die waardebepalingskriteria waarvan geldige afleidings betreffende die student se leerervaring gemaak kan word. ’n Bestaande instrument met 36 items waarmee baccalaureus-verpleegkundestudente se prestasie in die probleemgebaseerde leertutoriale geëvalueer is, is aan kundiges in

  14. 40 CFR 80.820 - What gasoline is subject to the toxics performance requirements of this subpart?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false What gasoline is subject to the toxics... PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Gasoline Toxics Gasoline Toxics Performance Requirements § 80.820 What gasoline is subject to the toxics performance...

  15. When ears drive hands: the influence of contact sound on reaching to grasp.

    Directory of Open Access Journals (Sweden)

    Umberto Castiello

    Full Text Available BACKGROUND: Most research on the roles of auditory information and its interaction with vision has focused on perceptual performance. Little is known on the effects of sound cues on visually-guided hand movements. METHODOLOGY/PRINCIPAL FINDINGS: We recorded the sound produced by the fingers upon contact as participants grasped stimulus objects which were covered with different materials. Then, in a further session the pre-recorded contact sounds were delivered to participants via headphones before or following the initiation of reach-to-grasp movements towards the stimulus objects. Reach-to-grasp movement kinematics were measured under the following conditions: (i congruent, in which the presented contact sound and the contact sound elicited by the to-be-grasped stimulus corresponded; (ii incongruent, in which the presented contact sound was different to that generated by the stimulus upon contact; (iii control, in which a synthetic sound, not associated with a real event, was presented. Facilitation effects were found for congruent trials; interference effects were found for incongruent trials. In a second experiment, the upper and the lower parts of the stimulus were covered with different materials. The presented sound was always congruent with the material covering either the upper or the lower half of the stimulus. Participants consistently placed their fingers on the half of the stimulus that corresponded to the presented contact sound. CONCLUSIONS/SIGNIFICANCE: Altogether these findings offer a substantial contribution to the current debate about the type of object representations elicited by auditory stimuli and on the multisensory nature of the sensorimotor transformations underlying action.

  16. Learning to control a brain-machine interface for reaching and grasping by primates.

    Directory of Open Access Journals (Sweden)

    Jose M Carmena

    2003-11-01

    Full Text Available Reaching and grasping in primates depend on the coordination of neural activity in large frontoparietal ensembles. Here we demonstrate that primates can learn to reach and grasp virtual objects by controlling a robot arm through a closed-loop brain-machine interface (BMIc that uses multiple mathematical models to extract several motor parameters (i.e., hand position, velocity, gripping force, and the EMGs of multiple arm muscles from the electrical activity of frontoparietal neuronal ensembles. As single neurons typically contribute to the encoding of several motor parameters, we observed that high BMIc accuracy required recording from large neuronal ensembles. Continuous BMIc operation by monkeys led to significant improvements in both model predictions and behavioral performance. Using visual feedback, monkeys succeeded in producing robot reach-and-grasp movements even when their arms did not move. Learning to operate the BMIc was paralleled by functional reorganization in multiple cortical areas, suggesting that the dynamic properties of the BMIc were incorporated into motor and sensory cortical representations.

  17. Neuroprosthesis for retraining reaching and grasping functions in severe hemiplegic patients.

    Science.gov (United States)

    Popovic, Milos R; Thrasher, T Adam; Zivanovic, Vera; Takaki, Jennifer; Hajek, Vlasta

    2005-01-01

    During the course of rehabilitation hemiplegic patients who have Chedoke McMaster Stages of Motor Recovery scores 4 and 5 measured three weeks after onset of stroke often improve their arm and hand function to the point that they can later use it in the activities of daily living (ADL) (1). These patients can be considered to have mild arm and hand paralysis since they can grasp objects and manipulate them with minor restrictions in the range of movement and force. On the other hand, hemiplegic patients who have Chedoke McMaster Stages of Motor Recovery scores 1 and 2 measured three weeks after onset of stroke, during the course of rehabilitation seldom improve their arm and hand function, and when they do, the improvements are not sufficient to allow these patients to use the arm and hand in ADL (1). These patients can be also described as patients who have severe arm and hand paralysis. Patients with severe arm and hand paralysis cannot move their arm and hand voluntarily at all or have very limited voluntary movements that cannot be used to carry out ADL. In recent years a variety of treatments such as constraint induced therapy, functional electrical therapy, biofeedback therapy, and robotics assisted therapies, were proposed which main objective is to improve reaching and grasping functions in subjects with unilateral arm paralysis. These therapies have shown encouraging results in patients with mild arm and hand paralysis. However, the efficacy of these therapies was limited when they were applied to patients with severe arm and hand paralysis. This article describes a new rehabilitation technique that can improve both reaching and grasping functions in hemiplegic patients with severe unilateral arm paralysis. A neuroprosthesis that applies surface electrical stimulation technology was used to retrain hemiplegic patients who had severe arm and hand paralysis to reach and grasp. The neuroprosthesis was applied both to acute and long-term hemiplegic patients

  18. Grasping convergent evolution in syngnathids: a unique tale of tails.

    Science.gov (United States)

    Neutens, C; Adriaens, D; Christiaens, J; De Kegel, B; Dierick, M; Boistel, R; Van Hoorebeke, L

    2014-06-01

    Seahorses and pipehorses both possess a prehensile tail, a unique characteristic among teleost fishes, allowing them to grasp and hold onto substrates such as sea grasses. Although studies have focused on tail grasping, the pattern of evolutionary transformations that made this possible is poorly understood. Recent phylogenetic studies show that the prehensile tail evolved independently in different syngnathid lineages, including seahorses, Haliichthys taeniophorus and several types of so-called pipehorses. This study explores the pattern that characterizes this convergent evolution towards a prehensile tail, by comparing the caudal musculoskeletal organization, as well as passive bending capacities in pipefish (representing the ancestral state), pipehorse, seahorse and H. taeniophorus. To study the complex musculoskeletal morphology, histological sectioning, μCT-scanning and phase contrast synchrotron scanning were combined with virtual 3D-reconstructions. Results suggest that the independent evolution towards tail grasping in syngnathids reflects at least two quite different strategies in which the ancestral condition of a heavy plated and rigid system became modified into a highly flexible one. Intermediate skeletal morphologies (between the ancestral condition and seahorses) could be found in the pygmy pipehorses and H. taeniophorus, which are phylogenetically closely affiliated with seahorses. This study suggests that the characteristic parallel myoseptal organization as already described in seahorse (compared with a conical organization in pipefish and pipehorse) may not be a necessity for grasping, but represents an apomorphy for seahorses, as this pattern is not found in other syngnathid species possessing a prehensile tail. One could suggest that the functionality of grasping evolved before the specialized, parallel myoseptal organization seen in seahorses. However, as the grasping system in pipehorses is a totally different one, this cannot be

  19. Grasping with the Press of a Button: Grasp-selective Responses in the Human Anterior Intraparietal Sulcus Depend on Nonarbitrary Causal Relationships between Hand Movements and End-effector Actions.

    Science.gov (United States)

    Frey, Scott H; Hansen, Marc; Marchal, Noah

    2015-06-01

    Evidence implicates ventral parieto-premotor cortices in representing the goal of grasping independent of the movements or effectors involved [Umilta, M. A., Escola, L., Intskirveli, I., Grammont, F., Rochat, M., Caruana, F., et al. When pliers become fingers in the monkey motor system. Proceedings of the National Academy of Sciences, U.S.A., 105, 2209-2213, 2008; Tunik, E., Frey, S. H., & Grafton, S. T. Virtual lesions of the anterior intraparietal area disrupt goal-dependent on-line adjustments of grasp. Nature Neuroscience, 8, 505-511, 2005]. Modern technologies that enable arbitrary causal relationships between hand movements and tool actions provide a strong test of this hypothesis. We capitalized on this unique opportunity by recording activity with fMRI during tasks in which healthy adults performed goal-directed reach and grasp actions manually or by depressing buttons to initiate these same behaviors in a remotely located robotic arm (arbitrary causal relationship). As shown previously [Binkofski, F., Dohle, C., Posse, S., Stephan, K. M., Hefter, H., Seitz, R. J., et al. Human anterior intraparietal area subserves prehension: A combined lesion and functional MRI activation study. Neurology, 50, 1253-1259, 1998], we detected greater activity in the vicinity of the anterior intraparietal sulcus (aIPS) during manual grasp versus reach. In contrast to prior studies involving tools controlled by nonarbitrarily related hand movements [Gallivan, J. P., McLean, D. A., Valyear, K. F., & Culham, J. C. Decoding the neural mechanisms of human tool use. Elife, 2, e00425, 2013; Jacobs, S., Danielmeier, C., & Frey, S. H. Human anterior intraparietal and ventral premotor cortices support representations of grasping with the hand or a novel tool. Journal of Cognitive Neuroscience, 22, 2594-2608, 2010], however, responses within the aIPS and premotor cortex exhibited no evidence of selectivity for grasp when participants employed the robot. Instead, these regions showed

  20. Upper Limb Rehabilitation Robot Powered by PAMs Cooperates with FES Arrays to Realize Reach-to-Grasp Trainings

    Science.gov (United States)

    Tu, Xikai; Han, Hualin; Huang, Jian; Li, Jian; Su, Chen; Jiang, Xiaobo; He, Jiping

    2017-01-01

    The reach-to-grasp activities play an important role in our daily lives. The developed RUPERT for stroke patients with high stiffness in arm flexor muscles is a low-cost lightweight portable exoskeleton rehabilitation robot whose joints are unidirectionally actuated by pneumatic artificial muscles (PAMs). In order to expand the useful range of RUPERT especially for patients with flaccid paralysis, functional electrical stimulation (FES) is taken to activate paralyzed arm muscles. As both the exoskeleton robot driven by PAMs and the neuromuscular skeletal system under FES possess the highly nonlinear and time-varying characteristics, iterative learning control (ILC) is studied and is taken to control this newly designed hybrid rehabilitation system for reaching trainings. Hand function rehabilitation refers to grasping. Because of tiny finger muscles, grasping and releasing are realized by FES array electrodes and matrix scan method. By using the surface electromyography (EMG) technique, the subject's active intent is identified. The upper limb rehabilitation robot powered by PAMs cooperates with FES arrays to realize active reach-to-grasp trainings, which was verified through experiments. © 2017 Xikai Tu et al.

  1. Upper Limb Rehabilitation Robot Powered by PAMs Cooperates with FES Arrays to Realize Reach-to-Grasp Trainings

    Science.gov (United States)

    Su, Chen; Jiang, Xiaobo

    2017-01-01

    The reach-to-grasp activities play an important role in our daily lives. The developed RUPERT for stroke patients with high stiffness in arm flexor muscles is a low-cost lightweight portable exoskeleton rehabilitation robot whose joints are unidirectionally actuated by pneumatic artificial muscles (PAMs). In order to expand the useful range of RUPERT especially for patients with flaccid paralysis, functional electrical stimulation (FES) is taken to activate paralyzed arm muscles. As both the exoskeleton robot driven by PAMs and the neuromuscular skeletal system under FES possess the highly nonlinear and time-varying characteristics, iterative learning control (ILC) is studied and is taken to control this newly designed hybrid rehabilitation system for reaching trainings. Hand function rehabilitation refers to grasping. Because of tiny finger muscles, grasping and releasing are realized by FES array electrodes and matrix scan method. By using the surface electromyography (EMG) technique, the subject's active intent is identified. The upper limb rehabilitation robot powered by PAMs cooperates with FES arrays to realize active reach-to-grasp trainings, which was verified through experiments. PMID:29065566

  2. Evaluating the subject-performed task effect in healthy older adults: relationship with neuropsychological tests

    Directory of Open Access Journals (Sweden)

    Ana Rita Silva

    2015-04-01

    Full Text Available Background: An enhancement in recall of simple instructions is found when actions are performed in comparison to when they are verbally presented – the subject-performed task (SPT effect. This enhancement has also been found with older adults. However, the reason why older adults, known to present a deficit in episodic memory, have a better performance for this type of information remains unclear. In this article, we explored this effect by comparing the performance on the SPT task with the performance on other tasks, in order to understand the underlying mechanisms that may explain this effect. Objective: We hypothesized that both young and older adult groups should show higher recall in SPT compared with the verbal learning condition, and that the differences between age groups should be lower in the SPT condition. We aimed to explore the correlations between these tasks and known neuropsychological tests, and we also measured source memory for the encoding condition. Design: A mixed design was used with 30 healthy older adults, comparing their performance with 30 healthy younger adults. Each participant was asked to perform 16 simple instructions (SPT condition and to only read the other 16 instructions (Verbal condition – VT. The test phase included a free recall task. Participants were also tested with a set of neuropsychological measures (speed of processing, working memory and verbal episodic memory. Results: The SPT effect was found for both age groups; but even for SPT materials, group differences in recall persisted. Source memory was found to be preserved for the two groups. Simple correlations suggested differences in correlates of SPT performance between the two groups. However, when controlling for age, the SPT and VT tasks correlate with each other, and a measure of episodic memory correlated moderately with both SPT and VT performance. Conclusions: A strong effect of SPT was observed for all but one, which still displayed the

  3. The role of vision in perching and grasping for MAVs

    Science.gov (United States)

    Thomas, Justin; Loianno, Giuseppe; Daniilidis, Kostas; Kumar, Vijay

    2016-05-01

    In this work, we provide an overview of vision-based control for perching and grasping for Micro Aerial Vehicles. We investigate perching on at, inclined, or vertical surfaces as well as visual servoing techniques for quadrotors to enable autonomous perching by hanging from cylindrical structures using only a monocular camera and an appropriate gripper. The challenges of visual servoing are discussed, and we focus on the problems of relative pose estimation, control, and trajectory planning for maneuvering a robot with respect to an object of interest. Finally, we discuss future challenges to achieve fully autonomous perching and grasping in more realistic scenarios.

  4. Software engineering capability for Ada (GRASP/Ada Tool)

    Science.gov (United States)

    Cross, James H., II

    1995-01-01

    The GRASP/Ada project (Graphical Representations of Algorithms, Structures, and Processes for Ada) has successfully created and prototyped a new algorithmic level graphical representation for Ada software, the Control Structure Diagram (CSD). The primary impetus for creation of the CSD was to improve the comprehension efficiency of Ada software and, as a result, improve reliability and reduce costs. The emphasis has been on the automatic generation of the CSD from Ada PDL or source code to support reverse engineering and maintenance. The CSD has the potential to replace traditional prettyprinted Ada Source code. A new Motif compliant graphical user interface has been developed for the GRASP/Ada prototype.

  5. Occupational performance in daily life activities of subjects hospitalized because of chronic malnutrition

    Directory of Open Access Journals (Sweden)

    Lauren Machado Pinto

    2013-08-01

    Full Text Available : Introduction: Malnutrition is configured as a health condition that causes deficits in occupational performance. Objective: To establish a correlation between nutritional status and occupational performance in activities of daily life (ADLs according to the desnutrition state level. Methodology: A descriptive, exploratory, cross-sectional evaluation of 50 patients diagnosed with chronic malnutrition admitted to a University Hospital in Curitiba, Parana state. We used the Functional Independence Measure (FIM and a semi-structured questionnaire in which the subjects named the three main performance limiting reasons. The Kruskal-Wallis test was used to identify the existence of differences between at least two groups in the analysis, while the test of Multiple Comparisons was used to determine which pairs of groups showed statistically significant differences at 95% significance level (p ≤ 0.05. Results: We assessed 28 (56% female and 22 (44% male patients with mean age of 50.16 (±16.74 for one year. Out of these, 19 (38% presented mild chronic malnutrition, 16 (32% showed moderate chronic malnutrition, and 14 (28% presented severe chronic malnutrition. We identified changes particularly in activities evaluated in the use of motor FIM, with relevant alterations of dependence level for the states of moderate to severe malnutrition. Patients’ complaints were in agreement with those pointed by the literature as symptoms of malnutrition. Conclusion: This study confirms the correlation between deterioration in nutritional status and high dependence level upon ADLs.

  6. Effort provides its own reward: endeavors reinforce subjective expectation and evaluation of task performance.

    Science.gov (United States)

    Wang, Lei; Zheng, Jiehui; Meng, Liang

    2017-04-01

    Although many studies have investigated the relationship between the amount of effort invested in a certain task and one's attitude towards the subsequent reward, whether exerted effort would impact one's expectation and evaluation of performance feedback itself still remains to be examined. In the present study, two types of calculation tasks that varied in the required effort were adopted, and we resorted to electroencephalography to probe the temporal dynamics of how exerted effort would affect one's anticipation and evaluation of performance feedback. In the high-effort condition, a more salient stimulus-preceding negativity was detected during the anticipation stage, which was accompanied with a more salient FRN/P300 complex (a more positive P300 and a less negative feedback-related negativity) in response to positive outcomes in the evaluation stage. These results suggested that when more effort was invested, an enhanced anticipatory attention would be paid toward one's task performance feedback and that positive outcomes would be subjectively valued to a greater extent.

  7. Performance of Hybrid Steel Fibers Reinforced Concrete Subjected to Air Blast Loading

    Directory of Open Access Journals (Sweden)

    Mohammed Alias Yusof

    2013-01-01

    Full Text Available This paper presents the results of the experimental data and simulation on the performance of hybrid steel fiber reinforced concrete (HSFRC and also normal reinforced concrete (NRC subjected to air blast loading. HSFRC concrete mix consists of a combination of 70% long steel hook end fibre and also 30% of short steel hook end fibre with a volume fraction of 1.5% mix. A total of six concrete panels were subjected to air blast using plastic explosive (PE4 weighing 1 kg each at standoff distance of 0.3 meter. The parameters measured are mode of failure under static and blast loading and also peak overpressure that resulted from detonation using high speed data acquisition system. In addition to this simulation work using AUTODYN was carried out and validated using experimental data. The experimental results indicate that hybrid steel fiber reinforced concrete panel (HSFRC possesses excellent resistance to air blast loading as compared to normal reinforced concrete (NRC panel. The simulation results were also found to be close with experimental data. Therefore the results have been validated using experimental data.

  8. COMT Val158Met modulates subjective responses to intravenous nicotine and cognitive performance in abstinent smokers

    Science.gov (United States)

    Herman, Aryeh I.; Jatlow, Peter I.; Gelernter, Joel; Listman, Jennifer B.; Sofuoglu, Mehmet

    2013-01-01

    The COMT Val158Met polymorphism may be a risk factor for nicotine addiction. This study examined the influence of the COMT Val158Met polymorphism on subjective, physiological, and cognitive effects of intravenous (IV) nicotine use in African American (AAs) (n=56) and European American (EAs) (n=68) smokers. Overnight abstinent smokers received saline followed by 0.5 and 1.0 mg/70 kg doses of nicotine, administered 30 minutes apart. Smokers with Val/Val genotype, compared to Met carriers, had greater negative subjective effects from IV nicotine and had more severe withdrawal severity following overnight abstinence from smoking. Women with Val/Val genotype reported greater difficulty concentrating and irritability than men with Val/Val or Met carrier genotypes. The Val/Val genotype was associated with better performance on the math task and in AA smokers it was associated with greater systolic blood pressure. These results support the rationale of pharmacologically inhibiting COMT to aid with smoking cessation among Val/Val genotype smokers. PMID:23459442

  9. Subjective Preference of Cellists for the Delay Time of a Single Reflection in a Performance

    Science.gov (United States)

    SATO, S.; ANDO, Y.; OTA, S.

    2000-04-01

    To provide knowledge useful in designing the stage enclosure in a concert hall, Nakayama reported the subjective preference of alto-recorder players for sound fields with a single reflection [Acustica54, 217-221 (1984)]. The present study evaluates the subjective preferences, with regard to ease of performance, of five cello soloists for the delay time of a single reflection. The scale values of preference for the delay time of a single reflection were obtained using a paired comparison method, and the results were compared with those for the alto-recorder players and listeners. The scale values of preference for both individuals and for global cellists with regard to the delay time of reflection can be expressed by a single approximate formula, normalizing the delay time by the most-preferred delay time observed for different music motifs. A notable finding is that the most-preferred delay time of a single reflection for each cellist can be calculated from the amplitude of the reflection and the minimum value of the effective duration (τe)minof the running autocorrelation function of the music motifs played by each cellist.

  10. Life events, salivary cortisol, and cognitive performance in nondemented subjects: a population-based study.

    Science.gov (United States)

    Ouanes, Sami; Castelao, Enrique; Gebreab, Sirak; von Gunten, Armin; Preisig, Martin; Popp, Julius

    2017-03-01

    Older people are particularly exposed to stressful events, known to activate the hypothalamus-pituitary-adrenal axis resulting in increased cortisol levels. High cortisol has been associated with deleterious effects on cognition. We hypothesized that stressful life events could increase cortisol secretion leading to cognitive impairment. A cross-sectional analysis was conducted using data from Colaus/PsyColaus, a longitudinal population-based study among Lausanne residents. Salivary cortisol samples were obtained from 796 nondemented subjects aged at least 65. A neuropsychological battery was used to assess cognitive performance and determine the Clinical Dementia Rating Sum of Boxes (CDRSOB). Lifetime life events and their subjective impact were assessed using a validated questionnaire. The total impact of life events was associated neither with cortisol area under the curve (AUC) nor with CDRSOB nor with any cognitive domain performance. The CDRSOB was associated with the cortisol AUC, controlling for age, sex, body mass index, education and depressive symptoms (p = 0.003; B = 0.686 [0.240; 1.333]; r = 0.114). This association between CDRSOB and the cortisol AUC remained significant after controlling for life events total impact (p = 0.040; B = 0.591 [0.027; 1.155]; r = 0.106). These findings do not support the hypothesis that stressful life events increase cortisol secretion leading to cognitive impairment. The association of higher cortisol levels with poorer cognition might be not a mere reflection of stressful events but rather explained by other factors, yet to be elucidated. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Metformin improves performance in high-intensity exercise, but not anaerobic capacity in healthy male subjects.

    Science.gov (United States)

    Learsi, S K; Bastos-Silva, V J; Lima-Silva, A E; Bertuzzi, R; De Araujo, G G

    2015-10-01

    The aim of this study was to determine the ergogenic effects of metformin in high-intensity exercise, as well as its effects on anaerobic capacity, in healthy and physically active men. Ten subjects (mean (± standard deviation) maximal oxygen uptake (V˙O2max ) 38.6 ± 4.5 mL/kg per min) performed the following tests in a cycle ergometer: (i) an incremental test; (ii) six submaximal constant workload tests at 40%-90% (V˙O2max ); and (iii) two supramaximal tests (110% (V˙O2max ). Metformin (500 mg) or placebo was ingested 60 min before the supramaximal test. There were no significant differences between the placebo and metformin groups in terms of maximum accumulated oxygen deficit (2.8 ± 0.6 vs 3.0 ± 0.8 L, respectively; P = 0.08), lactate concentrations (7.8 ± 2.6 vs 7.5 ± 3.0 mmol/L, respectively; P = 0.75) or O2 consumed in either the last 30 s of exercise (40.4 ± 4.4 vs 39.9 ± 4.0 mL/kg per min, respectively; P = 0.35) or the first 110 s of exercise (29.0 ± 2.5 vs 29.5 ± 3.0 mL/kg per min, respectively; P = 0.42). Time to exhaustion was significantly higher after metformin than placebo ingestion (191 ± 33 vs 167 ± 32 s, respectively; P = 0.001). The fast component of V˙O2 recovery was higher in the metformin than placebo group (12.71 vs 12.18 mL/kg per min, respectively; P = 0.025). Metformin improved performance and anaerobic alactic contribution during high-intensity exercise, but had no effect on overall anaerobic capacity in healthy subjects. © 2015 Wiley Publishing Asia Pty Ltd.

  12. Objective and subjective assessments of lighting in a hospital setting: implications for health, safety and performance.

    Science.gov (United States)

    Dianat, Iman; Sedghi, Ali; Bagherzade, Javad; Jafarabadi, Mohammad Asghari; Stedmon, Alex W

    2013-01-01

    A field study was conducted to evaluate the illumination levels, to examine the effect of lighting conditions (including lighting characteristics and disturbances) on employee satisfaction, job performance, safety and health, and to compare the employees' perception of lighting level with actual illuminance levels in a hospital setting using both questionnaire and physical illuminance measurements. The illumination levels varied across different locations within the hospital and were lower than standards for 52.2% of the workplaces surveyed. Most respondents indicated that at least one of the four lighting characteristics (i.e. light level, type of light sources, light colour and use of daylight) was inappropriate, and that at least one of the three lighting disturbances (i.e. flickering lights, glare and unwanted shadows) was a major disturbance to them. The employees' perceptions of illuminance generally reflected the actual illuminance levels. The more appropriate maintenance or installation of lighting fixtures was rated as the most appropriate for improving lighting. The findings suggest that environmental ergonomics should be given a more prominent role in hospital building and workplace design to support safer healthcare facilities (for staff and potentially for patients). Good lighting is essential to improve employee performance, health and safety. The findings suggest that quantitative physical measurements should be supplemented by qualitative subjective assessments to provide a more holistic approach where specific details about the lighting condition in each working environment are incorporated from the workers' perspective.

  13. Functional asymmetries in early learning during right, left, and bimanual performance in right-handed subjects.

    Science.gov (United States)

    Aznárez-Sanado, Maite; Fernández-Seara, Maria A; Loayza, Francis R; Pastor, Maria A

    2013-03-01

    To elucidate differences in activity and connectivity during early learning due to the performing hand. Twenty right-handed subjects were recruited. The neural correlates of explicit visuospatial learning executed with the right, the left hand, and bimanually were investigated using functional magnetic resonance imaging. Connectivity analyses were carried out using the psychophysiological interactions model, considering right and left anterior putamen as index regions. A common neural network was found for the three tasks during learning. Main activity increases were located in posterior cingulate cortex, supplementary motor area, parietal cortex, anterior putamen, and cerebellum (IV-V), whereas activity decrements were observed in prefrontal regions. However, the left hand task showed a greater recruitment of left hippocampal areas when compared with the other tasks. In addition, enhanced connectivity between the right anterior putamen and motor cortical and cerebellar regions was found for the left hand when compared with the right hand task. An additional recruitment of brain regions and increased striato-cortical and striato-cerebellar functional connections is needed when early learning is performed with the nondominant hand. In addition, access to brain resources during learning may be directed by the dominant hand in the bimanual task. Copyright © 2012 Wiley Periodicals, Inc.

  14. Stability Criterion of Linear Stochastic Systems Subject to Mixed H2/Passivity Performance

    Directory of Open Access Journals (Sweden)

    Cheung-Chieh Ku

    2015-01-01

    Full Text Available The H2 control scheme and passivity theory are applied to investigate the stability criterion of continuous-time linear stochastic system subject to mixed performance. Based on the stochastic differential equation, the stochastic behaviors can be described as multiplicative noise terms. For the considered system, the H2 control scheme is applied to deal with the problem on minimizing output energy. And the asymptotical stability of the system can be guaranteed under desired initial conditions. Besides, the passivity theory is employed to constrain the effect of external disturbance on the system. Moreover, the Itô formula and Lyapunov function are used to derive the sufficient conditions which are converted into linear matrix inequality (LMI form for applying convex optimization algorithm. Via solving the sufficient conditions, the state feedback controller can be established such that the asymptotical stability and mixed performance of the system are achieved in the mean square. Finally, the synchronous generator system is used to verify the effectiveness and applicability of the proposed design method.

  15. Performance Evaluation on Transmission Tower-Line System with Passive Friction Dampers Subjected to Wind Excitations

    Directory of Open Access Journals (Sweden)

    Bo Chen

    2015-01-01

    Full Text Available The vibration control and performance evaluation on a transmission-tower line system by using friction dampers subjected to wind excitations are carried out in this study. The three-dimensional finite element (FE model of a transmission tower is firstly constructed. A two-dimensional lumped mass model of a transmission tower is developed for dynamic analysis. The analytical model of transmission tower-line system is proposed by taking the dynamic interaction between the tower and the transmission lines into consideration. The mechanical model of passive friction damper is presented by involving the effects of damper axial stiffness. The equation of motion of the transmission tower-line system incorporated with the friction dampers disturbed by wind excitations is established. A real transmission tower-line system is taken as an example to examine the feasibility and reliability of the proposed control approach. An extensive parameter study is carried out to find the optimal parameters of friction damper and to assess the effects of slipping force axial stiffness and hysteresis loop on control performance. The work on an example structure indicates that the application of friction dampers with optimal parameters could significantly reduce wind-induced responses of the transmission tower-line system.

  16. Hand Preference for Precision Grasping Predicts Language Lateralization

    Science.gov (United States)

    Gonzalez, Claudia L. R.; Goodale, Melvyn A.

    2009-01-01

    We investigated whether or not there is a relationship between hand preference for grasping and hemispheric dominance for language--and how each of these is related to other traditional measures of handedness. To do this we asked right- and left-handed participants to put together two different sets of 3D puzzles made out of big or very small…

  17. A GRASP algorithm for the container stowage slot planning problem

    DEFF Research Database (Denmark)

    Parreno, Francisco; Pacino, Dario; Alvarez-Valdes, Ramon

    2016-01-01

    integer programming formulation and a Greedy Randomized Adaptive Search Procedure (GRASP) to solve the problem. The approach is able to find high-quality solution within 1 s. We also provide comparison with the state-of-the-art on an existing and a new set of benchmark instances. (C) 2016 Elsevier Ltd...

  18. Modelling primate control of grasping for robotics applications

    CSIR Research Space (South Africa)

    Kleinhans, A

    2014-09-01

    Full Text Available -1 European Conference on Computer Vision (ECCV) Workshops, Zurich, Switzerland, 7 September 2014 Modelling primate control of grasping for robotics applications Ashley Kleinhans1, Serge Thill2, Benjamin Rosman1, Renaud Detry3 & Bryan Tripp4 1 CSIR...

  19. Corticospinal excitability preceding the grasping of emotion-laden stimuli.

    Directory of Open Access Journals (Sweden)

    Anaelli Aparecida Nogueira-Campos

    Full Text Available Evolutionary theories posit that emotions prime organisms for action. This study examined whether corticospinal excitability (CSE is modulated by the emotional valence of a to-be-grasped stimulus. CSE was estimated based on the amplitude of motor evoked potentials (MEPs elicited using transcranial magnetic stimulation (TMS and recorded on the first dorsal interosseous (FDI muscle. Participants were instructed to grasp (ACTION condition or just look at (NO-ACTION condition unpleasant, pleasant and neutral stimuli. TMS pulses were applied randomly at 500 or 250 ms before a go signal. MEP amplitudes were normalized within condition by computing a ratio for the emotion-laden stimuli by reference to the neutral stimuli. A divergent valence effect was observed in the ACTION condition, where the CSE ratio was higher during the preparation to grasp unpleasant compared to pleasant stimuli. In addition, the CSE ratio was lower for pleasant stimuli during the ACTION condition compared to the NO-ACTION condition. Altogether, these results indicate that motor preparation is selectively modulated by the valence of the stimulus to be grasped. The lower CSE for pleasant stimuli may result from the need to refrain from executing an imminent action.

  20. Development of Object and Grasping Knowledge by Robot Exploration

    DEFF Research Database (Denmark)

    Kraft, Dirk; Detry, Renaud; Pugeault, Nicolas

    2010-01-01

    We describe a bootstrapping cognitive robot system that—mainly based on pure exploration—acquires rich object representations and associated object-specific grasp affordances. Such bootstrapping becomes possible by combining innate competences and behaviours by which the system gradually enriches...

  1. Development of prosthesis grasp control systems on a robotic testbed

    NARCIS (Netherlands)

    Peerdeman, B.; Fabrizi, Ugo; Palli, Gianluca; Melchiorri, Claudio; Stramigioli, Stefano; Misra, Sarthak

    2012-01-01

    Modern myoelectric hand prostheses continue to increase in functionality, while their control is constrained by the limits of myoelectric input. This paper covers the development and testing of grasp control systems for multifunctional myoelectric prosthetic hands. The functionality of modern hand

  2. Unmanned Systems: A Lab-Based Robotic Arm for Grasping

    Science.gov (United States)

    2015-06-01

    A LAB-BASED ROBOTIC ARM FOR GRASPING by Arturo Jacinto II June 2015 Thesis Advisor: Richard M. Harkins Second Reader: Peter Crooker......learning opportunities for various student experiments including the initial selection, startup and development of the Robotic arm and glove controller

  3. Modeling the shape hierarchy for visually guided grasping

    CSIR Research Space (South Africa)

    Rezai, O

    2014-10-01

    Full Text Available The monkey anterior intraparietal area (AIP) encodes visual information about three-dimensional object shape that is used to shape the hand for grasping. We modeled shape tuning in visual AIP neurons and its relationship with curvature and gradient...

  4. Differences in performance on the functional movement screen between chronic low back pain patients and healthy control subjects

    OpenAIRE

    Ko, Min-Joo; Noh, Kyung-Hee; Kang, Min-Hyeok; Oh, Jae-Seop

    2016-01-01

    [Purpose] Differences in scores on the Functional Movement Screen between patients with chronic lower back pain and healthy control subjects were investigated. [Subjects and Methods] In all, 20 chronic lower back pain patients and 20 healthy control subjects were recruited. Chronic lower back pain patients and healthy controls performed the Functional Movement Screen (deep squat, hurdle step, inline lunge, shoulder mobility, active straight leg raise, trunk stability pushup, and rotary stabil...

  5. GRASP (Greedy Randomized Adaptive Search Procedures) applied to optimization of petroleum products distribution in pipeline networks; GRASP (Greedy Randomized Adaptative Search Procedures) aplicado ao 'scheduling' de redes de distribuicao de petroleo e derivados

    Energy Technology Data Exchange (ETDEWEB)

    Conte, Viviane Cristhyne Bini; Arruda, Lucia Valeria Ramos de; Yamamoto, Lia [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil)

    2008-07-01

    Planning and scheduling of the pipeline network operations aim the most efficient use of the resources resulting in a better performance of the network. A petroleum distribution pipeline network is composed by refineries, sources and/or storage parks, connected by a set of pipelines, which operate the transportation of petroleum and derivatives among adjacent areas. In real scenes, this problem is considered a combinatorial problem, which has difficult solution, which makes necessary methodologies of the resolution that present low computational time. This work aims to get solutions that attempt the demands and minimize the number of batch fragmentations on the sent operations of products for the pipelines in a simplified model of a real network, through by application of the local search metaheuristic GRASP. GRASP does not depend of solutions of previous iterations and works in a random way so it allows the search for the solution in an ampler and diversified search space. GRASP utilization does not demand complex calculation, even the construction stage that requires more computational effort, which provides relative rapidity in the attainment of good solutions. GRASP application on the scheduling of the operations of this network presented feasible solutions in a low computational time. (author)

  6. The Relationship between Happiness, Subjective Well-Being, Creativity and Job Performance of Primary School Teachers in Ramhormoz City

    Science.gov (United States)

    Jalali, Zohreh; Heidari, Alireza

    2016-01-01

    The research aimed to investigate the relationship between happiness, subjective well-being, creativity and job performance of primary school teachers in Ramhormoz City. Hence, a sample of 330 individuals was selected through random stratified sampling. The research tools included Oxford Happiness Inventory, Subjective Well-being Scale by Keyes…

  7. The influence of force feedback and visual feedback in grasping tissue laparoscopically.

    Science.gov (United States)

    Heijnsdijk, E A M; Pasdeloup, A; van der Pijl, A J; Dankelman, J; Gouma, D J

    2004-06-01

    Due to the limited force feedback provided by laparoscopic instruments, surgeons may have difficulty in applying the appropriate force on the tissue. The aim of this study was to determine the influence of force feedback and visual feedback on the exerted pinch force. A grasper with a force sensor in the jaws was developed. Subjects with and without laparoscopic experience grasped and pulled pig bowel with a force of 5 N. The applied pinch force was measured during tasks of 1-s and 1-min duration. Visual feedback was provided in half the measurements. Force feedback was adjusted by changing the mechanical efficiency of the forceps from 30% to 90%. The mean pinch force applied was 6.8 N (+/-0.5), whereas the force to prevent slippage was 3.0 N (+/-0.4). Improving the mechanical efficiency had no effect on the pinch force for the 1-s measurements. The amount of excessive pinch force when holding tissue for 1 min was lower at 30% mechanical efficiency compared with 90% (105% vs 131%, p = 0.04). The tissue slipped more often when the subject had no visual feedback (2% vs 8%, p = 0.02). Force feedback and visual feedback play a more limited role than expected in the task of grasping tissue with laparoscopic forceps.

  8. Anticipatory modulation of digit placement for grasp control is affected by Parkinson's disease.

    Directory of Open Access Journals (Sweden)

    Jamie R Lukos

    2010-02-01

    Full Text Available Successful object manipulation relies on the ability to form and retrieve sensorimotor memories of digit forces and positions used in previous object lifts. Past studies of patients affected by Parkinson's disease (PD have revealed that the basal ganglia play a crucial role in the acquisition and/or retrieval of sensorimotor memories for grasp control. Whereas it is known that PD impairs anticipatory control of digit forces during grasp, learning deficits associated with the planning of digit placement have yet to be explored. This question is motivated by recent work in healthy subjects revealing that anticipatory control of digit placement plays a crucial role for successful manipulation.We asked ten PD patients off medication and ten age-matched controls to reach, grasp and lift an object whose center of mass (CM was on the left, right or center. The only task requirement was to minimize object roll during lift. The CM remained the same across consecutive trials (blocked condition or was altered from trial to trial (random condition. We hypothesized that impairment of the basal ganglia-thalamo-cortical circuits in PD patients would reduce their ability to anticipate digit placement appropriate to the CM location. Consequently, we predicted that PD patients would exhibit similar digit placement in the blocked vs. random conditions and produce larger peak object rolls than that of control subjects. In the blocked condition, PD patients exhibited significantly weaker modulation of fingertip contact points to CM location and larger object roll than controls (p<0.05 and p<0.01, respectively. Nevertheless, both controls and PD patients minimized object roll more in the blocked than in the random condition (p<0.01.Our findings indicate that, even though PD patients may have a residual ability of anticipatory control of digit contact points and forces, they fail to implement a motor plan with the same degree of effectiveness as controls. We conclude

  9. Characterizing “fibrofog”: Subjective appraisal, objective performance, and task-related brain activity during a working memory task

    Directory of Open Access Journals (Sweden)

    Brian Walitt

    2016-01-01

    Full Text Available The subjective experience of cognitive dysfunction (“fibrofog” is common in fibromyalgia. This study investigated the relation between subjective appraisal of cognitive function, objective cognitive task performance, and brain activity during a cognitive task using functional magnetic resonance imaging (fMRI. Sixteen fibromyalgia patients and 13 healthy pain-free controls completed a battery of questionnaires, including the Multiple Ability Self-Report Questionnaire (MASQ, a measure of self-perceived cognitive difficulties. Participants were evaluated for working memory performance using a modified N-back working memory task while undergoing Blood Oxygen Level Dependent (BOLD fMRI measurements. Fibromyalgia patients and controls did not differ in working memory performance. Subjective appraisal of cognitive function was associated with better performance (accuracy on the working memory task in healthy controls but not in fibromyalgia patients. In fibromyalgia patients, increased perceived cognitive difficulty was positively correlated with the severity of their symptoms. BOLD response during the working memory task did not differ between the groups. BOLD response correlated with task accuracy in control subjects but not in fibromyalgia patients. Increased subjective cognitive impairment correlated with decreased BOLD response in both groups but in different anatomic regions. In conclusion, “fibrofog” appears to be better characterized by subjective rather than objective impairment. Neurologic correlates of this subjective experience of impairment might be separate from those involved in the performance of cognitive tasks.

  10. Effect of Protectants on the Fermentation Performance of Wine Yeasts Subjected to Osmotic Stress

    Directory of Open Access Journals (Sweden)

    Andrea Caridi

    2003-01-01

    Full Text Available During alcoholic fermentation of must from dried grapes, yeasts are subjected to very high sugar concentrations, besides other environmental stresses, and they modify their metabolic behaviour giving low ethanol yield and abnormally high acetic acid production. To investigate the protective effect of catechin, inositol, and SO2 on wine yeasts, three thermotolerant strains of Saccharomyces cerevisiae, selected for wine making of must from dried grapes, and three strains of Saccharomyces selected for the production of wine, were inoculated in a sample of must at very high osmotic strength. A significant (p<0.01 or p<0.05 relationship between the addition of 100 mg/L of catechin, inositol or SO2 to the grape must and the change in the metabolic behaviour of the yeasts was observed. Compared to the control and depending on strain and protectant, the fermentation rate after 3 days increased up to 55 %, the ethanol content of the wines increased up to 16 %, the unitary succinic acid production increased up to 55 %, the unitary acetic acid production decreased up to 53 %, and the unitary glycerol production decreased up to 69 %. So by adding catechin, inositol or SO2 to the grape must it is possible to minimise the abnormal fermentation performance that wine yeasts exhibit in wine making of must from dried grapes.

  11. Too much anticipation? Large anticipatory adjustments of grasping movements to minimal object manipulations.

    Science.gov (United States)

    Herbort, Oliver

    2015-08-01

    When humans grasp objects, the grasps foreshadow the intended object manipulation. It has been suggested that grasps are selected that lead to medial arm postures, which facilitate movement speed and precision, during critical phases of the object manipulation. In Experiment 1, it has been tested whether grasp selections lead to medial postures during rotations of a dial. Participants twisted their arms considerably before grasping the dial, even when the upcoming dial rotation was minimal (5°). Participants neither assumed a medial posture at any point during a short rotation, nor did they assume any of the postures involved in short rotations in the opposite direction. Thus, grasp selections did not necessarily lead to specific postures at any point of the object manipulation. Experiment 2 examined the effect of various grasps on the speed of dial rotations. A medial initial grasp resulted in the fastest dial rotations for most rotation angles. Spontaneously selected grasps were more excursed than necessary to maximize dial rotation speed. This apparent overshot might be explained by participants' sensitive to the variability of their grasps and is in line with the assumption that grasps facilitate control over the grasped object. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. New version: GRASP2K relativistic atomic structure package

    Science.gov (United States)

    Jönsson, P.; Gaigalas, G.; Bieroń, J.; Fischer, C. Froese; Grant, I. P.

    2013-09-01

    , Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 730252 No. of bytes in distributed program, including test data, etc.: 14808872 Distribution format: tar.gz Programming language: Fortran. Computer: Intel Xeon, 2.66 GHz. Operating system: Suse, Ubuntu, and Debian Linux 64-bit. RAM: 500 MB or more Classification: 2.1. Catalogue identifier of previous version: ADZL_v1_0 Journal reference of previous version: Comput. Phys. Comm. 177 (2007) 597 Does the new version supersede the previous version?: Yes Nature of problem: Prediction of atomic properties — atomic energy levels, oscillator strengths, radiative decay rates, hyperfine structure parameters, Landé gJ-factors, and specific mass shift parameters — using a multiconfiguration Dirac-Hartree-Fock approach. Solution method: The computational method is the same as in the previous GRASP2K [1] version except that for v3 codes the njgraf library module [2] for recoupling has been replaced by librang [3,4]. Reasons for new version: New angular libraries with improved performance are available. Also methodology for transforming from jj- to LSJ-coupling has been developed. Summary of revisions: New angular libraries where the coefficients of fractional parentage have been extended to j=9/2, making calculations feasible for the lanthanides and actinides. Inclusion of a new program jj2lsj, which reports the percentage composition of the wave function in LSJ. Transition programs have been modified to produce a file of transition data with one record for each transition in the same format as Atsp2K [C. Froese Fischer, G. Tachiev, G. Gaigalas and M.R. Godefroid, Comput. Phys. Commun. 176 (2007) 559], which identifies each atomic state by the total energy and a label for the CSF with the largest expansion coefficient in LSJ intermediate coupling. Updated to 64-bit architecture. A

  13. COMT Val158Met modulates subjective responses to intravenous nicotine and cognitive performance in abstinent smokers

    National Research Council Canada - National Science Library

    Herman, A I; Jatlow, P I; Gelernter, J; Listman, J B; Sofuoglu, M

    2013-01-01

    ...)/Val genotype, compared with methionine (Met) carriers, had greater negative subjective effects from IV nicotine and had more severe withdrawal severity following overnight abstinence from smoking...

  14. Longitudinal Associations of Subjective Memory with Memory Performance and Depressive Symptoms: Between-Person and Within-Person Perspectives

    Science.gov (United States)

    Hülür, Gizem; Hertzog, Christopher; Pearman, Ann; Ram, Nilam; Gerstorf, Denis

    2015-01-01

    Clinical diagnostic criteria for memory loss in adults typically assume that subjective memory ratings accurately reflect compromised memory functioning. Research has documented small positive between-person associations between subjective memory and memory performance in older adults. Less is known, however, about whether within-person fluctuations in subjective memory covary with within-person variance in memory performance and depressive symptoms. The present study applied multilevel models of change to nine waves of data from 27,395 participants of the Health and Retirement Study (HRS; mean age at baseline = 63.78; SD = 10.30; 58% women) to examine whether subjective memory is associated with both between-person differences and within-person variability in memory performance and depressive symptoms and explored the moderating role of known correlates (age, gender, education, and functional limitations). Results revealed that across persons, level of subjective memory indeed covaried with level of memory performance and depressive symptoms, with small-to-moderate between-person standardized effect sizes (0.19 for memory performance and 0.21 for depressive symptoms). Within individuals, occasions when participants scored higher than usual on a test of episodic memory or reported fewer-than-average depressive symptoms generated above-average subjective memory. At the within-person level, subjective memory ratings became more sensitive to within-person alterations in memory performance over time and those suffering from functional limitations were more sensitive to within-person alterations in memory performance and depressive symptoms. We take our results to suggest that within-person changes in subjective memory in part reflect monitoring flux in one’s own memory functioning, but are also influenced by flux in depressive symptoms. PMID:25244464

  15. Perceiving the Causes of Objective and Subjective Outcomes Following Motor Performance

    Science.gov (United States)

    Iso-Ahola, Seppo

    1978-01-01

    Subjective perceptions of outcomes (both success and failure) may vary considerably from those of the experimenter's, and causal attributions are based as much on subject's own perceptions of success and failure as on the experimenter's definitions of outcomes. (Author/MJB)

  16. Evaluation of upper extremity robot-assistances in subacute and chronic stroke subjects.

    Science.gov (United States)

    Ziherl, Jaka; Novak, Domen; Olenšek, Andrej; Mihelj, Matjaž; Munih, Marko

    2010-10-18

    Robotic systems are becoming increasingly common in upper extremity stroke rehabilitation. Recent studies have already shown that the use of rehabilitation robots can improve recovery. This paper evaluates the effect of different modes of robot-assistances in a complex virtual environment on the subjects' ability to complete the task as well as on various haptic parameters arising from the human-robot interaction. The MIMICS multimodal system that includes the haptic robot HapticMaster and a dynamic virtual environment is used. The goal of the task is to catch a ball that rolls down a sloped table and place it in a basket above the table. Our study examines the influence of catching assistance, pick-and-place movement assistance and grasping assistance on the catching efficiency, placing efficiency and on movement-dependent parameters: mean reaching forces, deviation error, mechanical work and correlation between the grasping force and the load force. The results with groups of subjects (23 subacute hemiparetic subjects, 10 chronic hemiparetic subjects and 23 control subjects) showed that the assistance raises the catching efficiency and pick-and-place efficiency. The pick-and-place movement assistance greatly limits the movements of the subject and results in decreased work toward the basket. The correlation between the load force and the grasping force exists in a certain phase of the movement. The results also showed that the stroke subjects without assistance and the control subjects performed similarly. The robot-assistances used in the study were found to be a possible way to raise the catching efficiency and efficiency of the pick-and-place movements in subacute and chronic subjects. The observed movement parameters showed that robot-assistances we used for our virtual task should be improved to maximize physical activity.

  17. Evaluation of upper extremity robot-assistances in subacute and chronic stroke subjects

    Directory of Open Access Journals (Sweden)

    Mihelj Matjaž

    2010-10-01

    Full Text Available Abstract Background Robotic systems are becoming increasingly common in upper extremity stroke rehabilitation. Recent studies have already shown that the use of rehabilitation robots can improve recovery. This paper evaluates the effect of different modes of robot-assistances in a complex virtual environment on the subjects' ability to complete the task as well as on various haptic parameters arising from the human-robot interaction. Methods The MIMICS multimodal system that includes the haptic robot HapticMaster and a dynamic virtual environment is used. The goal of the task is to catch a ball that rolls down a sloped table and place it in a basket above the table. Our study examines the influence of catching assistance, pick-and-place movement assistance and grasping assistance on the catching efficiency, placing efficiency and on movement-dependant parameters: mean reaching forces, deviation error, mechanical work and correlation between the grasping force and the load force. Results The results with groups of subjects (23 subacute hemiparetic subjects, 10 chronic hemiparetic subjects and 23 control subjects showed that the assistance raises the catching efficiency and pick-and-place efficiency. The pick-and-place movement assistance greatly limits the movements of the subject and results in decreased work toward the basket. The correlation between the load force and the grasping force exists in a certain phase of the movement. The results also showed that the stroke subjects without assistance and the control subjects performed similarly. Conclusions The robot-assistances used in the study were found to be a possible way to raise the catching efficiency and efficiency of the pick-and-place movements in subacute and chronic subjects. The observed movement parameters showed that robot-assistances we used for our virtual task should be improved to maximize physical activity.

  18. [Investigation on dental impression disinfection knowledge grasped by medical staff in stomatological hospitals].

    Science.gov (United States)

    Deng, Li-mei; Zhao, Fu-rong

    2008-10-01

    To investigate the situation about the dental impression disinfection knowledge of the medical staff in stomatological hospitals. A questionnaire investigation was conducted on 582 medical staff in five Grade A Class Three stomatological hospitals. The investigation items included demographic characteristics and knowledge on dental impression disinfection. Of 582 subjects, 424 subjects (72.85%) thought that the dental impressions should be disinfected. 76 persons chose 75% alcohol to disinfect the dental impressions, 26 persons chose povidone iodine or glutaral, 103 persons chose sterilization machine, 180 persons chose to wash with water, and 197 persons were unknown about the sterilization methods. The status of the staff grasping knowledge on dental impression disinfection was related with the working department. Our results suggest that it is necessary to strengthen the importance of impression disinfection to medical staff in stomatological hospitals. The consciousness of protection should be enhanced to reduce the cross infection in hospitals.

  19. Impaired cognitive performance in subjects with methamphetamine dependence during exposure to neutral versus methamphetamine-related cues.

    Science.gov (United States)

    Tolliver, Bryan K; Price, Kimber L; Baker, Nathaniel L; LaRowe, Steven D; Simpson, Annie N; McRae-Clark, Aimee L; Saladin, Michael E; DeSantis, Stacia M; Chapman, Elizabeth; Garrett, Margaret; Brady, Kathleen T

    2012-05-01

    Chronic methamphetamine abuse is associated with cognitive deficits that may impede treatment in methamphetamine-dependent patients. Exposure to methamphetamine-related cues can elicit intense craving in chronic users of the drug, but the effects of exposure to drug cues on cognitive performance in these individuals are unknown. This study assessed whether exposure to methamphetamine-related visual cues can elicit craving and/or alter dual task cognitive performance in 30 methamphetamine-dependent subjects and 30 control subjects in the laboratory. Reaction time, response errors, and inhibition errors were assessed on an auditory Go-No Go task performed by adult participants (total N = 60) while watching neutral versus methamphetamine-related video cues. Craving was assessed with the Within-Session Rating Scale modified for methamphetamine-dependent subjects. Exposure to methamphetamine-related cues elicited craving only in methamphetamine-dependent subjects. Even in the absence of methamphetamine cues, methamphetamine-dependent subjects exhibited slower reaction times and higher rates of both inhibition and response errors than control subjects did. Upon exposure to methamphetamine cues, rates of both response errors and inhibition errors increased significantly in methamphetamine-dependent subjects. Control subjects exhibited no increase in inhibition errors and only slightly increased rates of response errors upon exposure to methamphetamine cues. Response error rates, but not inhibition error rates or reaction times, during methamphetamine cue exposure were significantly associated with craving scores in methamphetamine-dependent subjects. Methamphetamine-dependent individuals exhibit cognitive performance deficits that are more pronounced during exposure to methamphetamine-related cues. Interventions that reduce cue reactivity may have utility in the treatment of methamphetamine dependence.

  20. SUBJECTIVITY AND HYBRIDITY IN THE AGE OF INTERACTIVE INTERNET MEDIA: THE MUSICAL PERFORMANCES OF CHARICE PEMPENGCO AND ARNEL PINEDA

    Directory of Open Access Journals (Sweden)

    Christi-Anne Castro

    2010-06-01

    Full Text Available This paper examines hybrid subjectivity in the performances by and in the reception of musical artists utilizing the technology of interactive Internet media. It focuses on the career trajectories of the popular Filipino music performers Charice Pempengco and Arnel Pineda, taking into account how their transnational presence and dissemination through internet media communities affect perceptions of locality, nationality and race.

  1. Performance Levels in Science and Other Subjects for Jamaican Adolescents Attending Single-Sex and Co-Educational High Schools.

    Science.gov (United States)

    Hamilton, Marlene A.

    1985-01-01

    Examination results from 1146 Jamaican high school students in single-sex and coeducational schools indicated students from coeducational schools had lower performance on all measures. A subsample provided more information on sex differences, performance in individual subjects, and students receiving grades of A or B. (DH)

  2. Modeling and Simulation of Grasping of Deformable Objects

    DEFF Research Database (Denmark)

    Fugl, Andreas Rune

    . The purpose of this thesis is to address the modeling and simulation of deformable objects, as applied to robotic grasping and manipulation. The main contributions of this work are: An evaluation of 3D linear elasticity used for robot grasping as implemented by a Finite Difference Method supporting regular...... and adaptively refined grids, a stable and accurate non-linear 2D beam model supporting large deformations and difficult boundary effects, a method for the estimation of material properties and pose from depth and colour images, a method for the learning of Peg-in-Hole actions, an outline for Laying-Down actions...... as well a throughout evaluation of the accuracy of models under large deformations....

  3. A pilot study to evaluate simulated driving performance and cognitive function in healthy subjects and patients with restless legs syndrome

    Directory of Open Access Journals (Sweden)

    Chen D

    2013-10-01

    Full Text Available Dan Chen,1 Paula Shaw,2 Daniel M Canafax,1,3 James Catesby Ware4 1XenoPort, Inc., Santa Clara, CA, USA; 2Charles River Northwest, Tacoma, WA, USA; 3Theravance Inc., South San Francisco, CA, USA; 4Division of Sleep Medicine, Eastern Virginia Medical School, Norfolk, VA, USA Objective: Symptoms of restless legs syndrome (RLS usually occur during the evening and night time, resulting in disrupted sleep and subsequent daytime fatigue. This study compared simulated driving performance, alertness, and cognitive function between healthy subjects and patients with a diagnosis of RLS. Methods: Fifteen healthy subjects and 15 untreated RLS subjects were enrolled and completed two driving tests. The first test occurred at 4 PM followed by the second test at 8 AM the next morning. Outcome measures included lane position variability (LPV, speed variability, frequency of simulated crashes (off-road events or collision, and brake reaction time. Other assessments included visual analog scale (VAS of alertness and the Brief Assessment of Cognition (BAC. Results: Overall, RLS patients and healthy subjects performed similarly on driving assessments. Two subjects within each group experienced off-road events. RLS patients had less alertness on the VAS than healthy subjects before and after driving assessments. Both groups scored similarly on the cognitive function assessments. Conclusion: Despite reported diminished alertness, RLS patients did not demonstrate impairment in driving or cognitive performance. Keywords: restless legs syndrome, simulated driving performance, cognitive function

  4. Grasp plannind under task-specific contact constraints

    OpenAIRE

    Rosales Gallegos, Carlos

    2013-01-01

    Several aspects have to be addressed before realizing the dream of a robotic hand-arm system with human-like capabilities, ranging from the consolidation of a proper mechatronic design, to the development of precise, lightweight sensors and actuators, to the efficient planning and control of the articular forces and motions required for interaction with the environment. This thesis provides solution algorithms for a main problem within the latter aspect, known as the {\\em grasp planning} prob...

  5. Modelling the shape hierarchy for visually guided grasping

    Directory of Open Access Journals (Sweden)

    Omid eRezai

    2014-10-01

    Full Text Available The monkey anterior intraparietal area (AIP encodes visual information about three-dimensional object shape that is used to shape the hand for grasping. We modelled shape tuning in visual AIP neurons and its relationship with curvature and gradient information from the caudal intraparietal area (CIP. The main goal was to gain insight into the kinds of shape parameterizations that can account for AIP tuning and that are consistent with both the inputs to AIP and the role of AIP in grasping. We first experimented with superquadric shape parameters. We considered superquadrics because they occupy a role in robotics that is similar to AIP, in that superquadric fits are derived from visual input and used for grasp planning. We also experimented with an alternative shape parameterization that was based on an Isomap dimension reduction of spatial derivatives of depth (i.e. distance from the observer to the object surface. We considered an Isomap-based model because its parameters lacked discontinuities between similar shapes. When we matched the dimension of the Isomap to the number of superquadric parameters, the superquadric model fit the AIP data somewhat more closely. However, higher-dimensional Isomaps provided excellent fits. Also, we found that the Isomap parameters could be approximated much more accurately than superquadric parameters by feedforward neural networks with CIP-like inputs. We conclude that Isomaps, or perhaps alternative dimension reductions of visual inputs to AIP, provide a promising model of AIP electrophysiology data. However (in contrast with superquadrics further work is needed to test whether such shape parameterizations actually provide an effective basis for grasp control.

  6. The Synthesis of Force Closure Grasps in the Plane.

    Science.gov (United States)

    1985-09-01

    TASK U Artificial Inteligence Laboratory AREA A WORK UN IT "NMUIERS ~( 545 Technology Square Cambridge, MA 02139 SI. CONTROLLING OFICE NAME ANO... ARTIFICIAL INThLLIX’ ENCE LABORATORY A. 1. Memo 861 September, 1985 The Synthesis of Force-Closure Grasps In the Plane DTIC ’VeL% ,#ECTE 1 VnDcNguyenU Abstract... Artificial In- telligenmcc Liabomatory of thle Massachuset Is hInsttute of Teclhnolog3 . Support for the Lahoratot * s Artificial Intelligence research is

  7. Detumbling control for kinematically redundant space manipulator post-grasping a rotational satellite

    Science.gov (United States)

    Wang, Mingming; Luo, Jianjun; Yuan, Jianping; Walter, Ulrich

    2017-12-01

    The objective of this paper is to establish a detumbling strategy and a coordination control scheme for a kinematically redundant space manipulator post-grasping a rotational satellite. First, the dynamics of the kinematically redundant space robot after grasping the target is presented, which lays the foundation for the coordination controller design. Subsequently, optimal detumbling and motion planning strategy for the post-capture phase is proposed based on the quartic Bézier curves and adaptive differential evolution (DE) algorithm subject to the specific constraints. Both detumbling time and control torques are taken into account for the generation of the optimal detumbling strategy. Furthermore, a coordination control scheme is presented to track the designed reference path while regulating the attitude of the chaser to a desired value, which successfully dumps the initial angular velocity of the rotational satellite and controls the base attitude synchronously. Simulation results are presented for detumbling a target with rotational motion using a 7 degree-of-freedom (DOF) redundant space manipulator, which demonstrates the effectiveness of the proposed method.

  8. Water- versus land-based exercise in elderly subjects: effects on physical performance and body composition

    National Research Council Canada - National Science Library

    Bergamin, Marco; Ermolao, Andrea; Tolomio, Silvia; Berton, Linda; Sergi, Giuseppe; Zaccaria, Marco

    2013-01-01

    The aim of this study was to assess the effectiveness of a 24-week exercise protocol carried out in geothermal spring water to improve overall physical function and muscle mass in a group of healthy elderly subjects...

  9. Evaluation of performance, safety, subject acceptance, and compliance of a disposable autoinjector for subcutaneous injections in healthy volunteers.

    Science.gov (United States)

    Berteau, Cecile; Schwarzenbach, Florence; Donazzolo, Yves; Latreille, Mathilde; Berube, Julie; Abry, Herve; Cotten, Joël; Feger, Celine; Laurent, Philippe E

    2010-10-05

    A disposable autoinjector was developed for subcutaneous (SC) self-injection by patients with chronic diseases. To verify its performance and evaluate its acceptance, a clinical study was conducted in healthy volunteers, comparing SC injections performed by subjects using the autoinjector with SC injections performed by nurses using a syringe. This was a randomized, single-center, crossover study comparing SC self-injection using an autoinjector with SC nurse-administered injection using a syringe. Two volumes (0.2 mL and 1 mL) were injected into healthy volunteers. Study objectives included assessment of the accuracy and consistency of the volume injected by the injection systems, and skin reaction and pain associated with the injection. The fluid depot in the SC tissue layer was evaluated by ultrasound. Subject acceptance was evaluated using questionnaires on attitudes and emotions towards the injection technique, and challenged by seeking the subjects' preferred system for a final study injection or future treatment. A total of 960 injections (480 with autoinjector, 480 with syringe) were performed in 40 subjects. There were no significant differences in mean fluid leakage and injected volumes between the systems. Pain associated with the injection was significantly lower with the auto-injector than with the syringe. Local skin reaction at the injection site was overall satisfactory. Injections were appropriately performed by all subjects. At study end, all 40 subjects preferred the autoinjector for a final study injection and for future treatment. This study indicated that the autoinjector used by the subject was similar to a syringe used by a nurse in terms of performance and safety in administering the injections, and better in terms of pain, overall acceptance, and preference.

  10. Endoscopic submucosal dissection using a novel grasping type scissors forceps.

    Science.gov (United States)

    Akahoshi, K; Akahane, H; Murata, A; Akiba, H; Oya, M

    2007-12-01

    Endoscopic submucosal dissection (ESD) with a knife is a technically demanding procedure that is associated with a high complication rate. The shortcoming of this method is the difficulty in fixing the knife to the target lesion. This difficulty can lead to unexpected incision, resulting in major complications such as perforation and bleeding. To reduce the risk of complications related to ESD, we developed a new grasping type scissors forceps (GSF), which can grasp and incise the targeted tissue using an electrosurgical current. The ESD procedure using the GSF was carried out in an animal model (resected porcine stomachs in vitro). After marking the lesion and injecting a solution into the submucosa, the lesion was separated from the surrounding normal mucosa following complete incision around the lesion using the GSF. A piece of submucosal tissue was grasped and cut with the GSF using an electrosurgical current to achieve submucosal exfoliation. ESD using the GSF was carried out safely and easily without unintentional incision. ESD using GSF appears to be an easy, safe, and technically efficient method for resecting gastrointestinal neoplasms.

  11. Effect of pencil grasp on the speed and legibility of handwriting after a 10-minute copy task in Grade 4 children.

    Science.gov (United States)

    Schwellnus, Heidi; Carnahan, Heather; Kushki, Azadeh; Polatajko, Helene; Missiuna, Cheryl; Chau, Tom

    2012-06-01

    To investigate the impact of common pencil grasp patterns on the speed and legibility of handwriting after a 10-minute copy task, intended to induce muscle fatigue, in typically developing children and in those non-proficient in handwriting. A total of 120 Grade 4 students completed a standardised handwriting assessment before and after a 10-minute copy task. The students indicated the perceived difficulty of the handwriting task at baseline and after 10 minutes. The students also completed a self-report questionnaire regarding their handwriting proficiency upon completion. The majority of the students rated higher effort after the 10-minute copy task than at baseline (rank sum: P = 0.00001). The effort ratings were similar for the different grasp patterns (multiple linear regression: F = 0.37, P = 0.895). For both typically developing children and those with handwriting issues, the legibility of the writing samples decreased after the 10-minute copy task but the speed of writing increased. CONCLUSIONS AND SIGNIFICANCE OF THE STUDY: The quality of the handwriting decreased after the 10-minute copy task; however, there was no difference in the quality or speed scores among the different pencil grasps before and after the copy task. The dynamic tripod pencil grasp did not offer any advantage over the lateral tripod or the dynamic or lateral quadrupod pencil grasps in terms of quality of handwriting after a 10-minute copy task. These four pencil grasp patterns performed equivalently. Our findings question the practice of having students adopt the dynamic tripod pencil grasp. © 2012 The Authors Australian Occupational Therapy Journal © 2012 Occupational Therapy Australia.

  12. Evaluation of performance, safety, subject acceptance, and compliance of a disposable autoinjector for subcutaneous injections in healthy volunteers

    OpenAIRE

    Berteau, Cecile; Schwarzenbach, Florence; Donazzolo, Yves; Latreille, Mathilde; Berube, Julie; Abry, Herve; Cotten, Jo?l; Feger, Celine; Laurent, Philippe E

    2010-01-01

    Objective: A disposable autoinjector was developed for subcutaneous (SC) self-injection by patients with chronic diseases. To verify its performance and evaluate its acceptance, a clinical study was conducted in healthy volunteers, comparing SC injections performed by subjects using the autoinjector with SC injections performed by nurses using a syringe. Methods: This was a randomized, single-center, crossover study comparing SC self-injection using an autoinjector with SC nurse-administered ...

  13. Multifocal intraparietal activation during discrimination of action intention in observed tool grasping.

    Science.gov (United States)

    Vingerhoets, G; Honoré, P; Vandekerckhove, E; Nys, J; Vandemaele, P; Achten, E

    2010-09-01

    The way we grasp an object varies depending on how we want to use that object, and this knowledge can be used to predict the object-related behavior of others. In this study, we assessed the neural correlates that determine the action intention of another person based on observed prehensile movements. Fourteen right-handed volunteers watched video clips of a person performing right-handed transitive grasping gestures that were either aimed at displacing or using a tool-object. Clips showing the grasping and displacement of neutral shapes served as a control condition. By discrimination of the actor's intention, three roughly symmetrical foci were activated in the anterior, middle, and caudal segments of the intraparietal sulci, and in the fusiform gyri and parts of the lateral occipital complex. Anterior intraparietal activation has been associated with the representation of object goals (object specific), and the present findings extend its involvement to functional goals (use-specific). Activation in the middle intraparietal region during intention discrimination was very similar to the activation elicited in a saccadic localizer task, suggesting a relation with spatial attention and eye movements. The caudal intraparietal region has been related with visuospatial guidance of reaching, and its activation during action intention discrimination indicates that the visuospatial properties of the observed reaching movement contribute to understanding of actions. As these parietal regions are strongly linked with motor behavior, our results appear to support the motor simulation hypothesis for action understanding with the preferential recruitment of the mirror-neuron system. This could at least be the case when no contextual information other than the visual properties of the movement is provided to discriminate the intention of an observed hand action. Copyright (c) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

  14. A genome-wide supported psychiatric risk variant in NCAN influences brain function and cognitive performance in healthy subjects.

    Science.gov (United States)

    Raum, Heidelore; Dietsche, Bruno; Nagels, Arne; Witt, Stephanie H; Rietschel, Marcella; Kircher, Tilo; Krug, Axel

    2015-01-01

    The A allele of the single nucleotide polymorphism (SNP) rs1064395 in the NCAN gene has recently been identified as a susceptibility factor for bipolar disorder and schizophrenia. NCAN encodes neurocan, a brain-specific chondroitin sulfate proteoglycan that is thought to influence neuronal adhesion and migration. Several lines of research suggest an impact of NCAN on neurocognitive functioning. In the present study, we investigated the effects of rs1064395 genotype on neural processing and cognitive performance in healthy subjects. Brain activity was measured with functional magnetic resonance imaging (fMRI) during an overt semantic verbal fluency task in 110 healthy subjects who were genotyped for the NCAN SNP rs1064395. Participants additionally underwent comprehensive neuropsychological testing. Whole brain analyses revealed that NCAN risk status, defined as AA or AG genotype, was associated with a lack of task-related deactivation in a large left lateral temporal cluster extending from the middle temporal gyrus to the temporal pole. Regarding neuropsychological measures, risk allele carriers demonstrated poorer immediate and delayed verbal memory performance when compared to subjects with GG genotype. Better verbal memory performance was significantly associated with greater deactivation of the left temporal cluster during the fMRI task in subjects with GG genotype. The current data demonstrate that common genetic variation in NCAN influences both neural processing and cognitive performance in healthy subjects. Our study provides new evidence for a specific genetic influence on human brain function. © 2014 Wiley Periodicals, Inc.

  15. Secondary School Science Predictors of Academic Performance in University Bioscience Subjects

    Science.gov (United States)

    Green, Rod; Brown, Elizabeth; Ward, Alex

    2009-01-01

    In 2009 the Faculty of Health Sciences at La Trobe University in Melbourne, Australia is introducing a common first year for 11 different undergraduate courses in the faculty. Current prerequisite science entry requirements vary with course and range from none to at least two science or mathematics subjects and from [approximately]50 to 99 in…

  16. Effect of fish oil on cognitive performance in older subjects: a randomized, controlled trial

    NARCIS (Netherlands)

    van de Rest, O.; Geleijnse, J.M.; Kok, F. J.; van Staveren, W.A.; Dullemeijer, C.; Olde Rikkert, M.G.M.; Beekman, A.T.F.; de Groot, C.P.

    2008-01-01

    Background: High intake of n-3 polyunsaturated fatty acids may protect against age-related cognitive decline. However, results from epidemiologic studies are inconclusive, and results from randomized trials in elderly subjects without dementia are lacking. Objective: To investigate the effect of

  17. Subjective vs objective predictors of functional knee joint performance in anterior cruciate ligament-reconstructed patients

    DEFF Research Database (Denmark)

    Holsgaard-Larsen, Anders; Jensen, Carsten; Aagaard, Per

    2014-01-01

    BACKGROUND: Associations between objective and subjective measures of knee function may facilitate rehabilitation in ACL-patients. AIM: The aim of this study is to investigate if a test-battery of functional and/or muscle outcomes are associated with Knee osteoarthritis outcome score (KOOS) subsc...

  18. Subspecialty Exposure in a Psychiatry Clerkship Does Not Improve Student Performance in the Subject Examination

    Science.gov (United States)

    Retamero, Carolina; Ramchandani, Dilip

    2013-01-01

    Objective: The authors compared the NBME subject examination scores and subspecialty profiles of 3rd-year medical students who were assigned to psychiatry subspecialties during their clerkship with those who were not. Method: The authors collated and analyzed the shelf examination scores, the clinical grades, and the child psychiatry and emergency…

  19. Effect of fish oil on cognitive performance in older subjects: a randomized, controlled trial.

    NARCIS (Netherlands)

    Rest, O van de; Geleijnse, J.M.; Kok, F.J.; Staveren, W.A. van; Dullemeijer, C.; Olderikkert, M.G.; Beekman, A.T.; Groot, CP de

    2008-01-01

    BACKGROUND: High intake of n-3 polyunsaturated fatty acids may protect against age-related cognitive decline. However, results from epidemiologic studies are inconclusive, and results from randomized trials in elderly subjects without dementia are lacking. OBJECTIVE: To investigate the effect of

  20. Differences between Functional and Subjective Overconfidence in Postdiction Judgments of Test Performance

    Science.gov (United States)

    Shake, Matthew C.; Shulley, Leah J.

    2014-01-01

    Introduction: Recent research has shown that students tend to be overconfident when judging future performance on coursework, particularly students with lower academic ability. Some research suggests that these lower performing students are "doubly cursed" in that they are not only less capable of assessing their own performance, but…

  1. Associations of subjective vitality with DNA damage, cardiovascular risk factors and physical performance

    DEFF Research Database (Denmark)

    Maynard, Scott; Keijzers, Guido; Hansen, A-M

    2015-01-01

    To examine associations of DNA damage, cardiovascular risk factors and physical performance with vitality, in middle-aged men. We also sought to elucidate underlying factors of physical performance by comparing physical performance parameters to DNA damage parameters and cardiovascular risk factors....

  2. Is the Control of Applied Digital Forces During Natural Five-digit Grasping Affected by Carpal Tunnel Syndrome?

    Science.gov (United States)

    Chen, Po-Tsun; Jou, I-Ming; Lin, Chien-Ju; Chieh, Hsiao-Feng; Kuo, Li-Chieh; Su, Fong-Chin

    2015-07-01

    The impaired sensory function of the hand induced by carpal tunnel syndrome (CTS) is known to disturb dexterous manipulations. However, force control during daily grasping configuration among the five digits has not been a prominent focus of study. Because grasping is so important to normal function and use of a hand, it is important to understand how sensory changes in CTS affect the digit force of natural grasp. We therefore examined the altered patterns of digit forces applied during natural five-digit grasping in patients with CTS and compared them with those seen in control subjects without CTS. We hypothesized that the patients with CTS will grasp by applying larger forces with lowered pair correlations and more force variability of the involved digits than the control subjects. Specifically, we asked: (1) Is there a difference between patients with CTS and control subjects in applied force by digits during lift-hold-lower task? (2) Is there a difference in force correlation coefficient of the digit pairs? (3) Are there force variability differences during the holding phase? We evaluated 15 female patients with CTS and 15 control subjects matched for age, gender, and hand dominance. The applied radial forces (Fr) of the five digits were recorded by respective force transducers on a cylinder simulator during the lift-hold-lower task with natural grasping. The movement phases of the task were determined by a video-based motion capture system. The applied forces of the thumb in patients with CTS (7 ± 0.8 N; 95% CI, 7.2-7.4 N) versus control subjects (5 ± 0.8 N; 95% CI, 5.1-5.3 N) and the index finger in patients with CTS (3 ± 0.3 N; 95% CI, 3.2-3.3 N) versus control subjects (2 ± 0.3 N; 95% CI, 2.2-2.3 N) observed throughout most of the task were larger in the CTS group (p ranges 0.035-0.050 for thumb and 0.016-0.050 for index finger). In addition, the applied force of the middle finger in patients with CTS (1 ± 0.1 N; 95% CI, 1.3-1.4

  3. Spatiotemporal distribution of location and object effects in reach-to-grasp kinematics

    Science.gov (United States)

    Rouse, Adam G.

    2015-01-01

    In reaching to grasp an object, the arm transports the hand to the intended location as the hand shapes to grasp the object. Prior studies that tracked arm endpoint and grip aperture have shown that reaching and grasping, while proceeding in parallel, are interdependent to some degree. Other studies of reaching and grasping that have examined the joint angles of all five digits as the hand shapes to grasp various objects have not tracked the joint angles of the arm as well. We, therefore, examined 22 joint angles from the shoulder to the five digits as monkeys reached, grasped, and manipulated in a task that dissociated location and object. We quantified the extent to which each angle varied depending on location, on object, and on their interaction, all as a function of time. Although joint angles varied depending on both location and object beginning early in the movement, an early phase of location effects in joint angles from the shoulder to the digits was followed by a later phase in which object effects predominated at all joint angles distal to the shoulder. Interaction effects were relatively small throughout the reach-to-grasp. Whereas reach trajectory was influenced substantially by the object, grasp shape was comparatively invariant to location. Our observations suggest that neural control of reach-to-grasp may occur largely in two sequential phases: the first determining the location to which the arm transports the hand, and the second shaping the entire upper extremity to grasp and manipulate the object. PMID:26445870

  4. Subjective Perception of Sports Performance, Training, Sleep and Dietary Patterns of Malaysian Junior Muslim Athletes during Ramadan Intermittent Fasting

    OpenAIRE

    Singh, Rabindarjeet; Hwa, Ooi Cheong; Roy, Jolly; Jin, Chai Wen; Ismail, Siti Musyrifah; Lan, Mohamad Faizal; Hiong, Loo Lean; Aziz, Abdul-Rashid

    2011-01-01

    Purpose To examine the subjective perception of daily acute fasting on sports performance, training, sleep and dietary patterns of Muslim athletes during the Ramadan month. Methods Seven hundred and thirty-four (411 male and 323 female) Malaysian Junior-level Muslim athletes (mean age 16.3 ± 2.6 y) participated in the survey which was designed to establish the personal perception of their sport performance, sleep pattern, food and fluid intake during Ramadan fasting. The survey was conducted ...

  5. Performance Gaps between Online and Face-to-Face Courses: Differences across Types of Students and Academic Subject Areas

    Science.gov (United States)

    Xu, Di; Jaggars, Shanna S.

    2014-01-01

    Using a dataset containing nearly 500,000 courses taken by over 40,000 community and technical college students in Washington State, this study examines the performance gap between online and face-to-face courses and how the size of that gap differs across student subgroups and academic subject areas. While all types of students in the study…

  6. `Grasp of Practice' as a Reasoning Resource for Inquiry and Nature of Science Understanding

    Science.gov (United States)

    Ford, Michael

    2008-02-01

    This article articulates how a ‘grasp of practice’ serves as a reasoning resource for inquiry and citizenship abilities associated with nature of science (NOS) understanding. Theoretically, this resource is elaborated through an overlapping concern with ‘practice’ in two literatures, science studies and psychology of learning, bringing attention to two key roles in scientific practice, Critiquers and Constructors of claims. Empirically, this resource is made plausible by the results of an expert-novice study and a classroom study. In the expert-novice study, reactions of scientists and laypeople to science-related claims in the popular media were contrasted, underlining the appropriate ways scientists tend to Critique such claims. In the classroom study, sixth-grade students engaged in a 2-week ramp experiment, experiencing first hand the roles of Critiquers and Constructors of claims, and were subsequently assessed with a novel experimental task. Performances suggest that students had attained a grasp of practice, going well beyond mere execution of methods or procedures. These results challenge a common assumption that declarative knowledge best characterizes learning targets for supporting inquiry and NOS understanding.

  7. A multi-pad electrode based functional electrical stimulation system for restoration of grasp

    Directory of Open Access Journals (Sweden)

    Malešević Nebojša M

    2012-09-01

    Full Text Available Abstract Background Functional electrical stimulation (FES applied via transcutaneous electrodes is a common rehabilitation technique for assisting grasp in patients with central nervous system lesions. To improve the stimulation effectiveness of conventional FES, we introduce multi-pad electrodes and a new stimulation paradigm. Methods The new FES system comprises an electrode composed of small pads that can be activated individually. This electrode allows the targeting of motoneurons that activate synergistic muscles and produce a functional movement. The new stimulation paradigm allows asynchronous activation of motoneurons and provides controlled spatial distribution of the electrical charge that is delivered to the motoneurons. We developed an automated technique for the determination of the preferred electrode based on a cost function that considers the required movement of the fingers and the stabilization of the wrist joint. The data used within the cost function come from a sensorized garment that is easy to implement and does not require calibration. The design of the system also includes the possibility for fine-tuning and adaptation with a manually controllable interface. Results The device was tested on three stroke patients. The results show that the multi-pad electrodes provide the desired level of selectivity and can be used for generating a functional grasp. The results also show that the procedure, when performed on a specific user, results in the preferred electrode configuration characteristics for that patient. The findings from this study are of importance for the application of transcutaneous stimulation in the clinical and home environments.

  8. Oral hapsis guides accurate hand preshaping for grasping food targets in the mouth.

    Science.gov (United States)

    Karl, Jenni M; Sacrey, Lori-Ann R; Doan, Jon B; Whishaw, Ian Q

    2012-08-01

    Preshaping the digits and orienting the hand when reaching to grasp a distal target is proposed to be optimal when guided by vision. A reach-to-grasp movement to an object in one's own mouth is a natural and commonly used movement, but there has been no previous description of how it is performed. The movement requires accuracy but likely depends upon haptic rather than visual guidance, leading to the question of whether the kinematics of this movement are similar to those with vision or whether the movement depends upon an alternate strategy. The present study used frame-by-frame video analysis and linear kinematics to analyze hand movements as participants reached for ethologically relevant food targets placed either at a distal location or in the mouth. When reaching for small and medium-sized food items (blueberries and donut balls) that had maximal lip-to-target contact, hand preshaping was equivalent to that used for visually guided reaching. When reaching for a large food item (orange slice) that extended beyond the edges of the mouth, hand preshaping was suboptimal compared to vision. Nevertheless, hapsis from the reaching hand was used to reshape and reorient the hand after first contact with the large target. The equally precise guidance of hand preshaping under oral hapsis is discussed in relation to the idea that hand preshaping, and its requisite neural circuitry, may have originated under somatosensory control, with secondary access by vision.

  9. Selective interference of grasp and space representations with number magnitude and serial order processing.

    Science.gov (United States)

    van Dijck, Jean-Philippe; Fias, Wim; Andres, Michael

    2015-10-01

    It has been proposed that the metrics of space, time and other magnitudes relevant for action are coupled through a generalized magnitude system that also contribute to number representation. Several studies capitalized on stimulus-response compatibility effects to show that numbers map onto left-right representations and grasp representations as a function of their magnitude. However, the tasks typically used do not allow disentangling magnitude from serial order processing. Here, we devised a working memory (WM) task where participants had to remember random sequences of numbers and perform a precision/whole-hand grip (Experiment 1) or a uni-manual left/right button press (Experiment 2) in response to numbers presented during the retention interval. This task does allow differentiating the interference of number magnitude and serial order with each set of responses. Experiment 1 showed that precision grips were initiated faster than whole-hand grips in response to small numbers, irrespective of their serial position in WM. In contrast, Experiment 2 revealed an advantage of right over left button presses as serial position increased, without any influence of number magnitude. These findings demonstrate that grasping and left-right movements overlap with distinct dimensions of number processing. These findings are discussed in the light of different theories explaining the interactions between numbers, space and action.

  10. Subjective Estimates of Job Performance after Job Preview: Determinants of Anticipated Learning Curves

    Science.gov (United States)

    Ackerman, Phillip L.; Shapiro, Stacey; Beier, Margaret E.

    2011-01-01

    When people choose a particular occupation, they presumably make an implicit judgment that they will perform well on a job at some point in the future, typically after extensive education and/or on-the-job experience. Research on learning and skill acquisition has pointed to a power law of practice, where large gains in performance come early in…

  11. A GRASP-based approach to the multi activity combined timetabling and crew scheduling problem considering a heterogeneous workforce

    Directory of Open Access Journals (Sweden)

    Diego Novoa

    2016-09-01

    Full Text Available This paper tackles an extension to the Multi-activity Combined Timetabling and Crew Scheduling Problem (MCTCSP. The goal of the original problem is to schedule the minimum number of homogenous workers required, in order to visit a set of customers characterized by services needed against schedule availability. However, since in home services it is common to have specialized workers, a mathematical model considering a heterogeneous workforce is proposed. As a solution, a GRASP-based algorithm is designed. In order to test the metaheuristic performance, 110 instances from the literature are adapted to include categorical skills. In addition, another 10 instances are randomly generated to consider large problems. The results show that the proposed GRASP finds optimal solutions in 46% of the cases and saves 40–96% computational time.

  12. Interest of the MICROSTAR Accelerometer to improve the GRASP Mission.

    Science.gov (United States)

    Perrot, E.; Lebat, V.; Foulon, B.; Christophe, B.; Liorzou, F.; Huynh, P. A.

    2015-12-01

    The Geodetic Reference Antenna in Space (GRASP) is a micro satellite mission concept proposed by JPL to improve the definition of the Terrestrial Reference Frame (TRF). GRASP collocates GPS, SLR, VLBI, and DORIS sensors on a dedicated spacecraft in order to establish precise and stable ties between the key geodetic techniques used to define and disseminate the TRF. GRASP also offers a space-based reference antenna for the present and future Global Navigation Satellite Systems (GNSS). By taking advantage of the new testing possibilities offer by the catapult facility at the ZARM drop tower, the ONERA's space accelerometer team proposes an up-dated version, called MICROSTAR, of its ultra sensitive electrostatic accelerometers which have contributed to the success of the last Earth's gravity missions GRACE and GOCE. Built around a cubic proof-mass, it provides the 3 linear accelerations with a resolution better than 10-11 ms-2/Hz1/2 into a measurement bandwidth between 10-3 Hz and 0.1 Hz and the 3 angular accelerations about its 3 orthogonal axes with 5´10-10 rad.s-2/Hz1/2 resolution. Integrated at the centre of mass of the satellite, MICROSTAR improves the Precise Orbit Determination (POD) by accurate measurement of the non-gravitational force acting on the satellite. It offers also the possibility to calibrate the change in the position of the satellite center of mass with an accuracy better than 100 μm as demonstrated in the GRACE mission. Assuming a sufficiently rigid structure between the antennas and the accelerometer, its data can participate to reach the mission objective of 1 mm precision for the TRF position.

  13. RCT - subjective physical performance and quality of life after a 6-month programmed sports therapy (PST) in patients with haemophilia.

    Science.gov (United States)

    Runkel, B; Von Mackensen, S; Hilberg, T

    2017-01-01

    Musculoskeletal bleedings lead to limitations in the locomotor system and consequently, in health-related quality of life (HRQoL) in patients with haemophilia (PwH). Sports therapy is increasingly recommended to improve their physical performance. Until today, randomised controlled studies investigating changes in physical performance in PwH are rare. This study investigates the impact of programmed sports therapy on the subjective physical performance and the HRQoL in PwH. A randomised controlled trial (RCT) was conducted with a training intervention for over 6 months. For this purpose, 64 PwH with moderate (n = 5) or severe (n = 59) haemophilia A (n = 57) or B (n = 7) were randomised into two groups - intervention (IG) or control group (CG). The HRQoL was assessed with the SF-36 questionnaire and the disease-specific Haem-A-QoL before and after the intervention. The subjective physical performance was tested by the HEP-Test-Q. After the 6-month training intervention, PwH in the IG subjectively reported significant better 'endurance' (P = 0.000) in the HEP-Test-Q compared to the CG. In the SF-36, a significant difference in the domains 'general health perceptions' (P = 0.005) and 'mental health' (P = 0.001) was detected. The haemophilia-specific HRQoL questionnaire showed a significant improvement in the dimensions 'feeling' (P = 0.049), 'work' (P = 0.046) and 'family' (P = 0.040). In the first RCT evaluating the impact of a 6-month training intervention on the subjective perception of PwH, an increase in subjective physical performance and some domains of HRQoL was demonstrated in the IG. Specific sports therapy should be included into the comprehensive treatment under supervision and monitoring by experienced staff. © 2016 John Wiley & Sons Ltd.

  14. Aircraft Route Recovery Based on An Improved GRASP Method

    Directory of Open Access Journals (Sweden)

    Yang He

    2017-01-01

    Full Text Available Aircrafts maintenance, temporary airport closures are common factors that disrupt normal flight schedule. The aircraft route recovery aims to recover original schedules by some strategies, including flights swaps, and cancellations, which is a NP-hard problem. This paper proposes an improved heuristic procedure based on Greedy Random Adaptive Search Procedure (GRASP to solve this problem. The effectiveness and high global optimization capability of the heuristic is illustrated through experiments based on large-scale problems. Compared to the original one, it is shown that the improved procedure can find feasible flight recovered schedules with lower cost in a short time.

  15. Performance of Pre-Stressed Sandwich Composites Subjected to Shock Wave Loading

    Directory of Open Access Journals (Sweden)

    Shukla A.

    2010-06-01

    Full Text Available The present paper experimentally studies the dynamic behaviour of prestressed sandwich composites under blast loading. The in-plane static compression loadings are implemented on the sandwich composites before they are subjected to the transverse shock wave loading. Three different pre-stress levels are chosen. 3-D realtime deformation data are captured by two high-speed photography systems: a backview Digital Image Correlation (DIC system and a side-view camera system. The results show that pre-stresses can induce local buckling in the front face-sheet of sandwich composites, consequently reduce the blast resistance of sandwich composites.

  16. The Mulligan ankle taping does not affect balance performance in healthy subjects: a prospective, randomized blinded trial.

    Science.gov (United States)

    de-la-Morena, Jose Maria Delfa; Alguacil-Diego, Isabel Maria; Molina-Rueda, Francisco; Ramiro-González, Maria; Villafañe, Jorge Hugo; Fernández-Carnero, Josué

    2015-05-01

    [Purpose] The aim of this study was to evaluate the immediate effects of Mulligan fibular taping on static and dynamic postural balance in healthy subjects using computerized dynamic posturography (CDP). [Subjects and Methods] Forty-four volunteers (26 males and 18 females) aged 21 ±2 years participated in the study. The Mulligan tape was applied by a specialist in this technique. The placebo group received a treatment with a similar tape but with several cuts to avoid the fibular repositioning effect produced by Mulligan tape. The Sensory Organization Test (SOT) and the Motor Control Test (MCT) were performed by each subject at baseline and after the interventions. Outcome measures included equilibrium and strategy scores from each trial and condition of the SOT, and speed of reaction (latency period) from the MCT. [Results] Mulligan ankle taping did not have an impact on postural control during static and dynamic balance in subjects with healthy ankles when compared with placebo taping. [Conclusion] There was no difference in, equilibrium and strategy (SOT) and speed of reaction (MCT) in any of the subjects in this study. Therefore, this study suggests that Mulligan ankle taping does not have an impact on balance in healthy subjects.

  17. The role of perspective in discriminating between social and non-social intentions from reach-to-grasp kinematics.

    Science.gov (United States)

    Ciardo, Francesca; Campanini, Isabella; Merlo, Andrea; Rubichi, Sandro; Iani, Cristina

    2017-04-25

    Making correct inferences regarding social and individual intentions may be crucial for successful interactions, especially when we are required to discriminate between cooperative and competitive behaviors. The results of previous studies indicate that reach-to-grasp kinematic parameters may be used to infer the social or individual outcome of a movement. However, the majority of the studies investigated this ability by presenting reach-to-grasp movements from a third-person perspective only. The aim of the present study was to assess whether the ability to recognize the intent associated to a reach-to-grasp movement varies as a function of perspective by manipulating the perspective of observation (second- and third-perspective) within participants. To this end, we presented participants with video clips of models performing a reach-to-grasp movement with different intents. The video clips were recorded both from a lateral view (third-person perspective) and from a frontal view (second-person perspective). After viewing the clips, in two subsequent tasks participants were asked to distinguish between social and non-social intentions by observing the initial phase of the same action recorded from the two different views. Results showed that, when a fast-speed movement was presented from a lateral view, participants were able to predict its social intention. In contrast, when the same movement was observed from a frontal view, performance was impaired. These results indicate that the ability to detect social intentions from motor cues can be biased by the visual perspective of the observer, specifically for fast-speed movements.

  18. Closed-Loop Task Difficulty Adaptation during Virtual Reality Reach-to-Grasp Training Assisted with an Exoskeleton for Stroke Rehabilitation

    Science.gov (United States)

    Grimm, Florian; Naros, Georgios; Gharabaghi, Alireza

    2016-01-01

    Stroke patients with severe motor deficits of the upper extremity may practice rehabilitation exercises with the assistance of a multi-joint exoskeleton. Although this technology enables intensive task-oriented training, it may also lead to slacking when the assistance is too supportive. Preserving the engagement of the patients while providing “assistance-as-needed” during the exercises, therefore remains an ongoing challenge. We applied a commercially available seven degree-of-freedom arm exoskeleton to provide passive gravity compensation during task-oriented training in a virtual environment. During this 4-week pilot study, five severely affected chronic stroke patients performed reach-to-grasp exercises resembling activities of daily living. The subjects received virtual reality feedback from their three-dimensional movements. The level of difficulty for the exercise was adjusted by a performance-dependent real-time adaptation algorithm. The goal of this algorithm was the automated improvement of the range of motion. In the course of 20 training and feedback sessions, this unsupervised adaptive training concept led to a progressive increase of the virtual training space (p virtual reality provides customized rehabilitation environments for severely affected stroke patients. This approach may facilitate motor learning by progressively challenging the subject in accordance with the individual capacity for functional restoration. It might be necessary to apply concurrent restorative interventions to translate these improvements into relevant functional gains of severely motor impaired patients in activities of daily living. PMID:27895550

  19. Concept mapping improves academic performance in problem solving questions in biochemistry subject

    National Research Council Canada - National Science Library

    Baig, Mukhtiar; Tariq, Saba; Rehman, Rehana; Ali, Sobia; Gazzaz, Zohair J

    2016-01-01

    To assess the effectiveness of concept mapping (CM) on the academic performance of medical students' in problem-solving as well as in declarative knowledge questions and their perception regarding CM...

  20. Effects of Sleep Hygiene Education on Subjective Sleep Quality and Academic Performance

    National Research Council Canada - National Science Library

    Şahin, Erkan Melih

    .... It is known that sleep quality and daytime sleepiness cause decrasing academic performans. For this reason we aimed to investigate the effects of a sleep hygiene education on sleep quality and academic performance of first year medical students...

  1. Relationship between ACE-DD polymorphism and diastolic performance in healthy subjects.

    Science.gov (United States)

    Di Pasquale, Pietro; Cannizzaro, Sergio; Scalzo, Sebastiano; Giubilato, Alfonso; Maringhini, Giorgio; Giambanco, Francesco; Sarullo, Filippo; Tarsia, Giandomenico; Giammanco, Marco; Gaspare, Parrinello; Paterna, Salvatore

    2004-05-01

    The ACE-D allele has been associated with cardiovascular disease. The study evaluates the relationship between the ACE-ID genotypes and diastolic function in healthy subjects after 6 years of follow-up. Two hundred and seventy-five healthy volunteers aged 25-55 years had normal physical examination, 12-lead ECG, acceptable echocardiographic windows and echocardiogram at entry. Venous blood was drawn for DNA analysis. Two hundred and forty-two subjects completed 6 years of follow-up. Three genetically distinct groups were obtained: ACE-DD group (n=71, 26F/45M, mean age 48 +/- 7 years); ACE-ID (n=115, 39F/76M, mean age 40 +/- 7 years); and ACE-II (n=56, 20F/36M, mean age 47 +/- 6 years). Significant differences in E/A ratio were found between ACE-DD and ACE-ID, and ACE II (p=0.028, <0.0001, 0.0001), respectively. After 6 years, echocardiography showed a significant reduction of E/A ratio in the ACE-DD group, p=0.0001. The data suggest that ACE-DD is associated with deteriorating myocardial diastolic properties.

  2. Relation of eye dominancy with color vision discrimination performance ability in normal subjects

    Directory of Open Access Journals (Sweden)

    Belkıs Koçtekin

    2013-10-01

    Full Text Available AIM: To evaluate the performance of dominant eye (DE for color vision discrimination ability among the medical students with normal color vision.CONCLUSION: The color vision discrimination performance ability was found prominent for DE. This superiority was attributed to higher sensitivityof the r/g local color spectral region. We conclude that DE has priority in r/g color spectral region, probably including inhibition of NDE.

  3. Effects of Sleep Hygiene Education on Subjective Sleep Quality and Academic Performance

    OpenAIRE

    Erkan Sahin

    2014-01-01

    Aim: Sleep problems are common in students with one third of university students reporting insufficient sleep. It is known that sleep quality and daytime sleepiness cause decrasing academic performans. For this reason we aimed to investigate the effects of a sleep hygiene education on sleep quality and academic performance of first year medical students. Material and Method: Self-reported sleep data and academic performance of 131 first grade medical students were collected. To all students e...

  4. Flupentixolhydrochloride in low dosages: effects on perceptual and psychomotor performance in emotionally stable and emotionally labile healthy subjects.

    Science.gov (United States)

    Rösler, F; Stieglitz, R D; Manzey, D

    1986-01-01

    Effects of flupentixol on performance were evaluated in a double-blind study with 107 healthy male subjects. Experimental factors were dosage (0, 1, and 2 mg Fluanxol 0.5/day), the trait variable 'neuroticism' (high vs. low score on a questionnaire scale), and time of measurement (before and after 4 days of treatment). Drug effects were measured by means of seven paper-and-pencil tests and eight apparatus tests covering the following cognitive functions: endurance in attention, spacial orientation, flexibility and speed of closure, perceptual speed, response speed, psychomotor coordination, knowledge of traffic rules, and basic motoric tempo. Univariate and multivariate ANOVAs disclosed that flupentixol has detrimental effects on perceptual and psychomotor functions, in particular when administered in a dosage of 2 mg/day. These treatment effects did not interact with the trait variable neuroticism. Nevertheless, there were substantial differences between emotionally stable and emotionally labile subjects in both absolute performance level and change of performance over time.

  5. Mismatch negativity and cognitive performance for the prediction of psychosis in subjects with at-risk mental state.

    Directory of Open Access Journals (Sweden)

    Yuko Higuchi

    Full Text Available BACKGROUND: A shorter duration of untreated psychosis has been associated with better prognosis in schizophrenia. In this study, we measured the duration mismatch negativity (dMMN, an event-related potential, and cognitive performance in subjects with at-risk mental state (ARMS, patients with first-episode or chronic schizophrenia, and healthy volunteers. The main interest was to determine if these neurocognitive measures predict progression to overt schizophrenia in ARMS subjects. METHODOLOGY/PRINCIPAL FINDINGS: Seventeen ARMS subjects, meeting the criteria of the Comprehensive Assessment of At-Risk Mental State, 31 schizophrenia patients (20 first-episode and 11 chronic and healthy controls (N=20 participated in the study. dMMN was measured by an auditory odd-ball paradigm at baseline. Neuropsychological performance was evaluated by the Japanese version of the Brief assessment of cognitive function of schizophrenia (BACS-J. The first-episode schizophrenia group showed significantly smaller amplitudes at frontal electrodes than did control subjects whereas chronic patients elicited smaller amplitudes at frontal and central electrodes, consistent with previous reports. During the follow-up period, 4 out of the 17 ARMS subjects transitioned to schizophrenia (converters while 13 did not (non-converters. Specifically, dMMN amplitudes of non-converters did not differ from those of healthy controls, while converters showed significantly smaller dMMN amplitudes at some electrodes compared to control subjects. Converters performed significantly worse on tests of working memory, verbal fluency, and attention/information processing than did non-converters. There was a significant positive correlation between dMMN amplitudes at the frontal electrodes and verbal fluency, as measured by the BACS, in the AMRS subjects as a whole. CONCLUSIONS/SIGNIFICANCE: ARMS subjects who later developed schizophrenia elicited smaller dMMN amplitudes to begin with, compared

  6. Comparison of the pedalling performance induced by magnetic and electrical stimulation cycle ergometry in able-bodied subjects.

    Science.gov (United States)

    Szecsi, J; Straube, A; Fornusek, C

    2014-04-01

    The purpose of the study was to compare the mechanical power and work generated by able-bodied subjects during functional magnetic stimulation (FMS) vs. functional electrical stimulation (FES) induced ergometer training conditions. Both stimulation methods were applied at a 30 Hz frequency to the quadriceps muscles of 22 healthy able-bodied subjects to induce cycling for 4× four minutes or until exhaustion. FMS was performed via large surface, cooled coils, while FES was applied with a typical stimulation setup used for cycling. Significantly more (pstimulation induced pain and fatigue mechanisms of the neuromuscular system. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

  7. Monocular-Based 6-Degree of Freedom Pose Estimation Technology for Robotic Intelligent Grasping Systems

    OpenAIRE

    Tao Liu; Yin Guo; Shourui Yang; Shibin Yin; Jigui Zhu

    2017-01-01

    Industrial robots are expected to undertake ever more advanced tasks in the modern manufacturing industry, such as intelligent grasping, in which robots should be capable of recognizing the position and orientation of a part before grasping it. In this paper, a monocular-based 6-degree of freedom (DOF) pose estimation technology to enable robots to grasp large-size parts at informal poses is proposed. A camera was mounted on the robot end-flange and oriented to measure several featured points...

  8. Can a multimedia tool help students' learning performance in complex biology subjects?

    Directory of Open Access Journals (Sweden)

    Pinar Koseoglu

    2015-11-01

    Full Text Available The aim of the present study was to determine the effects of multimedia-based biology teaching (Mbio and teacher-centered biology (TCbio instruction approaches on learners' biology achievements, as well as their views towards learning approaches. During the research process, an experimental design with two groups, TCbio (n = 22 and Mbio (n = 26, were used. The results of the study proved that the Mbio approach was more effective than the TCbio approach with regard to supporting meaningful learning, academic achievement, enjoyment and motivation. Moreover, the TCbio approach is ineffective in terms of time management, engaging attention, and the need for repetition of subjects. Additionally, the results were discussed in terms of teaching, learning, multimedia design as well as biology teaching/learning.

  9. Performances on simulator and da Vinci robot on subjects with and without surgical background.

    Science.gov (United States)

    Moglia, Andrea; Ferrari, Vincenzo; Melfi, Franca; Ferrari, Mauro; Mosca, Franco; Cuschieri, Alfred; Morelli, Luca

    2017-08-17

    To assess whether previous training in surgery influences performance on da Vinci Skills Simulator and da Vinci robot. In this prospective study, thirty-seven participants (11 medical students, 17 residents, and 9 attending surgeons) without previous experience in laparoscopy and robotic surgery performed 26 exercises at da Vinci Skills Simulator. Thirty-five then executed a suture using a da Vinci robot. The overall scores on the exercises at the da Vinci Skills Simulator show a similar performance among the groups with no statistically significant pair-wise differences (p robotic surgery, insignificant differences in the scores at the da Vinci Skills Simulator and at the da Vinci robot on inanimate models.

  10. Cultural performances: the zombie invasion, the death of the subject and other disorientation

    Directory of Open Access Journals (Sweden)

    Sainy C.B. Veloso

    2013-06-01

    Full Text Available The article considers how contemporary cultural performances indicial, the worldwide proliferation of fictional theme of the zombie apocalypse, through comic books, board games, movies, games, television serials, posters, rallies. Since then, reflects the theme and looks at this set of products and actions, limited the issue: the current crisis is a crisis of guidance within a world not interpretable, as demonstrates the zombie invasion? To this end, rests on concepts of cultural performances delimiters (GOFFMAN, 2011; social drama (TURNER, 1974; culture (GEERTZ, 1989; and social crisis (JAMESON, 1997; SENNETT, 1998.

  11. Electromyographic analysis of goal-directed grasping behavior in the American lobster

    National Research Council Canada - National Science Library

    Tomina, Yusuke; Takahata, Masakazu

    2014-01-01

    .... In order to quantitatively characterize the goal-directed grasping behavior with a time resolution fine enough for neurophysiological analysis of its initiation and control mechanisms, we made...

  12. Adding vibrotactile feedback to a myoelectric-controlled hand improves performance when online visual feedback is disturbed.

    Science.gov (United States)

    Raveh, Eitan; Portnoy, Sigal; Friedman, Jason

    2018-01-17

    We investigated whether adding vibrotactile feedback to a myoelectric-controlled hand, when visual feedback is disturbed, can improve performance during a functional test. For this purpose, able-bodied subjects, activating a myoelectric-controlled hand attached to their right hand performed the modified Box & Blocks test, grasping and manipulating wooden blocks over a partition. This was performed in 3 conditions, using a repeated-measures design: in full light, in a dark room where visual feedback was disturbed and no auditory feedback - one time with the addition of tactile feedback provided during object grasping and manipulation, and one time without any tactile feedback. The average time needed to transfer one block was measured, and an infrared camera was used to give information on the number of grasping errors during performance of the test. Our results show that when vibrotactile feedback was provided, performance time was reduced significantly, compared with when no vibrotactile feedback was available. Furthermore, the accuracy of grasping and manipulation was improved, reflected by significantly fewer errors during test performance. In conclusion, adding vibrotactile feedback to a myoelectric-controlled hand has positive effects on functional performance when visual feedback is disturbed. This may have applications to current myoelectric-controlled hands, as adding tactile feedback may help prosthesis users to improve their functional ability during daily life activities in different environments, particularly when limited visual feedback is available or desirable. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Heuristic methods using grasp, path relinking and variable neighborhood search for the clustered traveling salesman problem

    Directory of Open Access Journals (Sweden)

    Mário Mestria

    2013-08-01

    Full Text Available The Clustered Traveling Salesman Problem (CTSP is a generalization of the Traveling Salesman Problem (TSP in which the set of vertices is partitioned into disjoint clusters and objective is to find a minimum cost Hamiltonian cycle such that the vertices of each cluster are visited contiguously. The CTSP is NP-hard and, in this context, we are proposed heuristic methods for the CTSP using GRASP, Path Relinking and Variable Neighborhood Descent (VND. The heuristic methods were tested using Euclidean instances with up to 2000 vertices and clusters varying between 4 to 150 vertices. The computational tests were performed to compare the performance of the heuristic methods with an exact algorithm using the Parallel CPLEX software. The computational results showed that the hybrid heuristic method using VND outperforms other heuristic methods.

  14. Locomotion and Grasping impairment in preschoolers with autism spectrum disorder

    Directory of Open Access Journals (Sweden)

    Francesca Fulceri

    2015-08-01

    Full Text Available Objective: To investigate expressiveness of motor impairment in autism spectrum disorder (ASD and its correlation with developmental and clinical features of ASD. Method: Thirty-five male preschoolers with ASD completed the Peabody Developmental Motor Scales-2 (PDMS-2; Folio and Fewell, 2000 and underwent a multidisciplinary assessment including medical examination, standardized assessment of cognitive abilities, administration of Autism_Diagnostic_Observation_Schedule (ADOS and a parent interview about adaptive skills. Results: Results revealed a substantial impairment in locomotion and grasping skills. Both fine and gross motor skills were significantly correlated with non verbal IQ and adaptive behaviours (p<0.01 but not with chronological age or ADOS scores. Children with weaker motor skills have greater cognitive and adaptive behaviours deficits. Conclusions: Motor development in ASD can be detected at preschool age and locomotion and grasping skills are substantially the most impaired area. These findings support the need to assess motor skills in preschoolers with ASD in addition to other developmental skill areas. Along with the increasingly acknowledged importance of motor skills for subsequent social, cognitive, and communicative development our findings support the need to consider motor intervention as a key area in therapeutic program to improve outcome in preschoolers with ASD.

  15. Validation of a novel automatic sleep spindle detector with high performance during sleep in middle aged subjects

    DEFF Research Database (Denmark)

    Wendt, Sabrina Lyngbye; Christensen, Julie A. E.; Kempfner, Jacob

    2012-01-01

    Many of the automatic sleep spindle detectors currently used to analyze sleep EEG are either validated on young subjects or not validated thoroughly. The purpose of this study is to develop and validate a fast and reliable sleep spindle detector with high performance in middle aged subjects....... An automatic sleep spindle detector using a bandpass filtering approach and a time varying threshold was developed. The validation was done on sleep epochs from EEG recordings with manually scored sleep spindles from 13 healthy subjects with a mean age of 57.9 ± 9.7 years. The sleep spindle detector reached...... a mean sensitivity of 84.6 % and a mean specificity of 95.3 %. The sleep spindle detector can be used to obtain measures of spindle count and density together with quantitative measures such as the mean spindle frequency, mean spindle amplitude, and mean spindle duration....

  16. Structural Performance of a Hybrid FRP-Aluminum Modular Triangular Truss System Subjected to Various Loading Conditions

    Directory of Open Access Journals (Sweden)

    Dongdong Zhang

    2014-01-01

    Full Text Available A novel hybrid FRP-aluminum truss system has been employed in a two-rut modular bridge superstructure composed of twin inverted triangular trusses. The actual flexural behavior of a one-rut truss has been previously investigated under the on-axis loading test; however, the structural performance of the one-rut truss subjected to an off-axis load is still not fully understood. In this paper, a geometrical linear finite element model is introduced and validated by the on-axis loading test; the structural performance of the one-rut truss subjected to off-axis load was numerically obtained; the dissimilarities of the structural performance between the two different loading cases are investigated in detail. The results indicated that (1 the structural behavior of the off-axis load differs from that of the on-axis load, and the off-axis load is the critical loading condition controlling the structural performance of the triangular truss; (2 under the off-axis load, the FRP trussed members and connectors bear certain out-of-plane bending moments and are subjected to a complicated stress state; and (3 the stress state of these members does not match that of the initial design, and optimization for the redesign of these members is needed, especially for the pretightened teeth connectors.

  17. A within-subjects comparison of learning and memory performance before and after cardiac catheterization.

    NARCIS (Netherlands)

    Verwey, B.; Derikx, R.L.; Waarde, J.A. van; Essink, G.; Rooij, I.A.L.M. van; Zitman, F.G.

    2007-01-01

    OBJECTIVE: To investigate the influence of stress on the recall of neutral information in a clinical setting, a prospective study was performed on patients who were admitted to the hospital for cardiac catheterization. METHODS: During their hospital stay, 39 cardiac patients were tested for verbal

  18. Clearing the air : The effect of experimenter race on target's test performance and subjective experience

    NARCIS (Netherlands)

    Marx, DM; Goff, PA

    2005-01-01

    According to stereotype threat theory (Steele, 1997), stereotyped targets under-perform on challenging tests, in part because they are worried about being viewed in terms of the negative stereotype that they are intellectually inferior. How then are the negative effects of stereotype threat reduced

  19. Executive Functions in Older Adults With Autism Spectrum Disorder : Objective Performance and Subjective Complaints

    NARCIS (Netherlands)

    Davids, Roeliena C. D.; Groen, Yvonne; Berg, Ina J.; Tucha, Oliver M.; van Balkom, Ingrid D. C.

    Although deficits in Executive Functioning (EF) are reported frequently in young individuals with Autism Spectrum Disorders (ASD), they remain relatively unexplored later in life (> 50 years). We studied objective performance on EF measures (Tower of London, Zoo map, phonetic/semantic fluency) as

  20. International Differences in Subjective Performance Evaluation, Compensation and Career Dynamics in a Global Company

    DEFF Research Database (Denmark)

    Halse, Nikolaj; Smeets, Valerie Anne Rolande; Warzynski, Frederic Michel Patrick

    .S. and Asia (Japan and China). We try to understand why performance evaluation is distributed differently across countries, and how these differences affect wage growth, the size of the bonus and promotion decisions. We find that evaluations tend to be better on average at the headquarter, but also that wages...

  1. First year medical students' learning style preferences and their correlation with performance in different subjects within the medical course.

    Science.gov (United States)

    Hernández-Torrano, Daniel; Ali, Syed; Chan, Chee-Kai

    2017-08-08

    Students commencing their medical training arrive with different educational backgrounds and a diverse range of learning experiences. Consequently, students would have developed preferred approaches to acquiring and processing information or learning style preferences. Understanding first-year students' learning style preferences is important to success in learning. However, little is understood about how learning styles impact learning and performance across different subjects within the medical curriculum. Greater understanding of the relationship between students' learning style preferences and academic performance in specific medical subjects would be valuable. This cross-sectional study examined the learning style preferences of first-year medical students and how they differ across gender. This research also analyzed the effect of learning styles on academic performance across different subjects within a medical education program in a Central Asian university. A total of 52 students (57.7% females) from two batches of first-year medical school completed the Index of Learning Styles Questionnaire, which measures four dimensions of learning styles: sensing-intuitive; visual-verbal; active-reflective; sequential-global. First-year medical students reported preferences for visual (80.8%) and sequential (60.5%) learning styles, suggesting that these students preferred to learn through demonstrations and diagrams and in a linear and sequential way. Our results indicate that male medical students have higher preference for visual learning style over verbal, while females seemed to have a higher preference for sequential learning style over global. Significant associations were found between sensing-intuitive learning styles and performance in Genetics [β = -0.46, B = -0.44, p styles and performance in Genetics [β = 0.36, B = 0.43, p learning techniques. Instructors can also benefit by modifying and adapting more appropriate teaching approaches in these

  2. The prefrontal model revisited: double dissociations between young sleep deprived and elderly subjects on cognitive components of performance.

    Science.gov (United States)

    Tucker, Adrienne M; Stern, Yaakov; Basner, Robert C; Rakitin, Brian C

    2011-08-01

    The prefrontal model suggests that total sleep deprivation (TSD) and healthy aging produce parallel cognitive deficits. Here we decompose global performance on two common tasks into component measures of specific cognitive processes to pinpoint the source of impairments in elderly and young TSD participants relative to young controls and to each other. The delayed letter recognition task (DLR) was performed in 3 studies. The psychomotor vigilance task (PVT) was performed in 1 of the DLR studies and 2 additional studies. For DLR, young TSD (n=20, age=24.60 ± 0.62 years) and young control (n=17, age=24.00 ± 2.42); elderly (n=26, age=69.92 ± 1.06). For the PVT, young TSD (n=18, age=26.65 ± 4.57) and young control (n=16, age=25.19 ± 2.90); elderly (n=21, age=71.1 ± 4.92). Both elderly and young TSD subjects displayed impaired reaction time (RT), our measure of global performance, on both tasks relative to young controls. After decomposing global performance on the DLR, however, a double dissociation was observed as working memory scanning speed was impaired only in elderly subjects while other components of performance were impaired only by TSD. Similarly, for the PVT a second double dissociation was observed as vigilance impairments were present only in TSD while short-term response preparation effects were altered only in the elderly. The similarity between TSD and the elderly in impaired performance was evident only when examining global RT. In contrast, when specific cognitive components were examined double dissociations were observed between TSD and elderly subjects. This demonstrates the heterogeneity in those cognitive processes impaired in TSD versus the elderly.

  3. The impact of sleep duration and subject intelligence on declarative and motor memory performance: how much is enough?

    Science.gov (United States)

    Tucker, Matthew A; Fishbein, William

    2009-09-01

    Recent findings clearly demonstrate that daytime naps impart substantial memory benefits compared with equivalent periods of wakefulness. Using a declarative paired associates task and a procedural motor sequence task, this study examined the effect of two lengthier durations of nocturnal sleep [either a half night (3.5 h) or a full night (7.5 h) of sleep] on over-sleep changes in memory performance. We also assessed whether subject intelligence is associated with heightened task acquisition and, more importantly, whether greater intelligence translates to greater over-sleep declarative and procedural memory enhancement. Across both tasks, we demonstrate that postsleep performance gains are nearly equivalent, regardless of whether subjects obtain a half night or a full night of sleep. Remarkably, the over-sleep memory changes observed on both tasks are very similar to findings from studies examining performance following a daytime nap. Consistent with previous research, we also observed a strong positive correlation between amount of Stage 2 sleep and motor skill performance in the full-night sleep group. This finding contrasts with a highly significant correlation between spectral power in the spindle frequency band (12-15 Hz) and motor skill enhancement only in the half-night group, suggesting that sigma power and amount of Stage 2 sleep are both important for optimal motor memory processing. While subject intelligence correlated positively with acquisition and retest performance on both tasks, it did not correlate with over-sleep changes in performance on either task, suggesting that intelligence may not be a powerful modulator of sleep's effect on memory performance.

  4. Objective vs. Subjective Evaluation of Cognitive Performance During 0.4-MPa Dives Breathing Air or Nitrox.

    Science.gov (United States)

    Germonpré, Peter; Balestra, Costantino; Hemelryck, Walter; Buzzacott, Peter; Lafère, Pierre

    2017-05-01

    Divers try to limit risks associated with their sport, for instance by breathing enriched air nitrox (EANx) instead of air. This double blinded, randomized trial was designed to see if the use of EANx could effectively improve cognitive performance while diving. Eight volunteers performed two no-decompression dry dives breathing air or EANx for 20 min at 0.4 MPa. Cognitive functions were assessed with a computerized test battery, including MathProc and Ptrail. Measurements were taken before the dive, upon arrival and after 15 min at depth, upon surfacing, and at 30 min postdive. After each dive subjects were asked to identify the gas they had just breathed. Identification of the breathing gas was not possible on subjective assessment alone, while cognitive assessments showed significantly better performance while breathing EANx. Before the dives, breathing air, mean time to complete the task was 1795 ms for MathProc and 1905 ms for Ptrail. When arriving at depth MathProc took 1616 ms on air and 1523 ms on EANx, and Ptrail took 1318 ms on air and and 1356 ms on EANx, followed 15 min later by significant performance inhibition while breathing air during the ascent and the postdive phase, supporting the concept of late dive/postdive impairment. The results suggest that EANx could protect against decreased neuro-cognitive performance induced by inert gas narcosis. It was not possible for blinded divers to identify which gas they were breathing and differences in postdive fatigue between air and EANx diving deserve further investigation.Germonpré P, Balestra C, Hemelryck W, Buzzacott P, Lafère P. Objective vs. subjective evaluation of cognitive performance during 0.4-MPa dives breathing air or nitrox. Aerosp Med Hum Perform. 2017; 88(5):469-475.

  5. It matters how old you feel: Antecedents and performance consequences of average relative subjective age in organizations.

    Science.gov (United States)

    Kunze, Florian; Raes, Anneloes M L; Bruch, Heike

    2015-09-01

    This article extends the conceptual knowledge of average relative subjective age in organizations by exploring organizational-level antecedents and consequences of employees, on average, feeling younger than their chronological age. We draw from the theories of selection-optimization-compensation and socioemotional selectivity to build a theoretical framework for relative subjective age in organizations. We hypothesize that companies in which employees, on average, perceive themselves to be younger than they actually are have a higher average individual goal accomplishment and, in turn, experience higher company performance. We further hypothesize that employees' average experience of high work-related meaning relates to a lower subjective age in organizations. In addition, we assess the role of environmental dynamism and age-inclusive human resource management as moderators in this theoretical model. Through empirically testing this model in a multisource dataset, including 107 companies with 15,164 participating employees, we received support for the hypothesized relationships. Our results contribute to current debates in the scientific literature on age and have important practical implications in light of the demographic changes faced by many companies. This research indicates to both researchers and practitioners that it is not employees' chronological age but their subjective age, a factor that can be influenced, which drives organizational performance outcomes. (c) 2015 APA, all rights reserved).

  6. Effects of Background Music on Objective and Subjective Performance Measures in an Auditory BCI

    OpenAIRE

    Zhou, Sijie; Allison, Brendan Z.; Kübler, Andrea; Cichocki, Andrzej; Wang, Xingyu; Jin, Jing

    2016-01-01

    Several studies have explored brain computer interface (BCI) systems based on auditory stimuli, which could help patients with visual impairments. Usability and user satisfaction are important considerations in any BCI. Although background music can influence emotion and performance in other task environments, and many users may wish to listen to music while using a BCI, auditory, and other BCIs are typically studied without background music. Some work has explored the possibility of using po...

  7. Comparison of design procedures and observed performance of bridges subjected to lateral spreading

    OpenAIRE

    Turner, Benjamin J; Brandenberg, Scott J.; Stewart, Jonathan P.

    2014-01-01

    Recently developed guidelines for analyzing deep foundations in liquefiable soils are compared with the performance of a highway bridge and adjacent railroad bridge that suffered damage during the 2010 Mw 7.2 El Mayor-Cucapah earthquake in Baja California, Mexico. A span of the pile-supported railroad bridge collapsed due to movement of a pier from lateral spreading. The highway bridge, supported on drilled shafts, suffered moderate structural damage but did not collapse. An overview of the s...

  8. Subjective cognitive complaints and neuropsychological performance in former smokers with and without chronic obstructive pulmonary disease.

    Science.gov (United States)

    Brunette, Amanda M; Holm, Kristen E; Wamboldt, Frederick S; Kozora, Elizabeth; Moser, David J; Make, Barry J; Crapo, James D; Meschede, Kimberly; Weinberger, Howard D; Moreau, Kerrie L; Bowler, Russell P; Hoth, Karin F

    2017-08-02

    This study examined the association of perceived cognitive difficulties with objective cognitive performance in former smokers. We hypothesized that greater perceived cognitive difficulties would be associated with poorer performance on objective executive and memory tasks. Participants were 95 former smokers recruited from the COPDGene study. They completed questionnaires (including the Cognitive Difficulties Scale [CDS] and the Hospital Anxiety and Depression Scale [HADS]), neuropsychological assessment, and pulmonary function testing. Pearson correlations and t-tests were conducted to examine the bivariate association of the CDS (total score and subscales for attention/concentration, praxis, delayed recall, orientation for persons, temporal orientation, and prospective memory) with each domain of objective cognitive functioning (memory recall, executive functioning/processing speed, visuospatial processing, and language). Simultaneous multiple linear regression was used to further examine all statistically significant bivariate associations. The following covariates were included in all regression models: age, sex, pack-years, premorbid functioning (WRAT-IV Reading), HADS total score, and chronic obstructive pulmonary disease (COPD) status (yes/no based on GOLD criteria). In regression models, greater perceived cognitive difficulties overall (using CDS total score) were associated with poorer performance on executive functioning/processing speed tasks (b = -0.07, SE = 0.03, p = .037). Greater perceived cognitive difficulties on the CDS praxis subscale were associated with poorer performance on executive functioning/processing speed tasks (b = -3.65, SE = 1.25, p = .005), memory recall tasks (b = -4.60, SE = 1.75, p = .010), and language tasks (b = -3.89, SE = 1.39, p = .006). Clinicians should be aware that cognitive complaints may be indicative of problems with the executive functioning/processing speed and memory of former smokers with

  9. Effects of the handle diameter and tip angle of chopsticks on the food-serving performance of male subjects.

    Science.gov (United States)

    Wu, S P

    1995-12-01

    The effects of chopsticks handle diameter and tip angle on the food-serving performance of pinching food, pulling food, shearing food and thrusting food, were investigated in this study. A total of 24 male subjects was tested using 12 pairs of experimental chopsticks, consisting of three types of different handle diameters and four types of different tip angles. These results indicated that chopstick handle diameter and tip angle have a significant influence on eating efficiency, and that these two variables have a significant interaction. In addition, chopstick tip diameter also had significant effects on performance at the four tasks and subjective ratings. Generally, according to the results, when the chopsticks design is presented in terms of handle diameter, tip angle and tip diameter, a pair of chopsticks with 6 mm handle diameter x 2 degrees tip angle x 4 mm tip diameter would be optimum.

  10. Medical Student Dissection of Cadavers Improves Performance on Practical Exams but not on the NBME Anatomy Subject Exam

    OpenAIRE

    Sargent Jones, Leslie; Paulman, Lance E.; Thadani, Raj; Terracio, Louis

    2009-01-01

    We have examined whether cadaver dissection by first year medical students (MIs) affected their performance in two test measures: the NBME Gross Anatomy and Embryology Subject Exam (dissection-relevant questions only), and practical exams given at the end of each major section within the course. The dissections for the entire course were divided into 18 regional dissection units and each student was assigned to dissect one third of the regional units; the other two-thirds of the material was ...

  11. Functional knee brace use by non-injured subjects while performing an anaerobic capacity task: preliminary study.

    Science.gov (United States)

    Rishiraj, N; Taunton, J E; Lloyd-Smith, R; Niven, B; Regan, W; Woollard, R

    2010-12-01

    The objective of this paper was to investigate if performance was hindered in non-injured braced athletes during an anaerobic task. If performance was affected, could accommodation to wearing a knee brace occur and thus decreasing performance hindrance concern while using a functional knee brace (FKB). A 2x3 non-braced (NBr) and braced repeated measure factorial design. Five healthy athletes completed all testing. Subjects performed the Repeated High Intensity Shuttle Test (RHIST) over six days (three days NBr and three days braced). Running times were recorded each testing day to determine performance measures and percent fatigue levels while using a FKB and if accommodation to FKB use was possible. Non significant (F1,4=1.42, P=0.299) faster group mean performance time, was recorded for braced subjects relative to the non-braced condition. Although relatively faster performance levels were noted during the braced testing conditions during days 1 and 3 compared to the non-braced condition, these results were also not significant (F2,8=2.82, P=0.118). Lower percent fatigue level was recorded during all three braced days compared to non-braced days. Further, a tendency for accommodation to knee brace trend use was noted as the percentage performance difference between the two conditions had decreased by the last day of testing. Use of a knee brace did not hinder performance once accommodation to using the knee brace occurred and fatigue was not a factor while using a knee brace. Additional research, using a larger sample size and longer testing duration, is required to confirm the potential accommodation trend.

  12. Cardiopulmonary performance testing using a robotics-assisted tilt table: feasibility assessment in able-bodied subjects.

    Science.gov (United States)

    Saengsuwan, J; Laubacher, M; Nef, T; Hunt, K J

    2014-01-01

    Robotics-assisted tilt table technology was introduced for early rehabilitation of neurological patients. It provides cyclical stepping movement and physiological loading of the legs. The aim of the present study was to assess the feasibility of this type of device for peak cardiopulmonary performance testing using able-bodied subjects. A robotics-assisted tilt table was augmented with force sensors in the thigh cuffs and a work rate estimation algorithm. A custom visual feedback system was employed to guide the subjects' work rate and to provide real time feedback of actual work rate. Feasibility assessment focused on: (i) implementation (technical feasibility), and (ii) responsiveness (was there a measurable, high-level cardiopulmonary reaction?). For responsiveness testing, each subject carried out an incremental exercise test to the limit of functional capacity with a work rate increment of 5 W/min in female subjects and 8 W/min in males. 11 able-bodied subjects were included (9 male, 2 female; age 29.6 ± 7.1 years: mean ± SD). Resting oxygen uptake (O_{2}) was 4.6 ± 0.7 mL/min/kg and O_{2}peak was 32.4 ± 5.1 mL/min/kg; this mean O_{2}peak was 81.1% of the predicted peak value for cycle ergometry. Peak heart rate (HRpeak) was 177.5 ± 9.7 beats/min; all subjects reached at least 85% of their predicted HRpeak value. Respiratory exchange ratio (RER) at O_{2}peak was 1.02 ± 0.07. Peak work rate) was 61.3 ± 15.1 W. All subjects reported a Borg CR10 value for exertion and leg fatigue of 7 or more. The robotics-assisted tilt table is deemed feasible for peak cardiopulmonary performance testing: the approach was found to be technically implementable and substantial cardiopulmonary responses were observed. Further testing in neurologically-impaired subjects is warranted.

  13. School Achievement and Performance in Chilean High Schools: The Mediating Role of Subjective Wellbeing in School-Related Evaluations

    Directory of Open Access Journals (Sweden)

    Verónica López

    2017-07-01

    Full Text Available School achievement gaps and school failure are problematic issues in Latin America, and are mainly explained by the socio-economic status (SES of the students. What schools can do to improve school achievement and reduce school failure is a critical issue, both for school management and teacher training. In this study, we present the association of individual and school-related socio-emotional variables with school achievement and performance, controlling for the effects of SES. A probabilistic sample of 4,964 students, drawn from 191 schools enrolled in year 10 in urban areas of Chile, answered questionnaires assessing subjective wellbeing, social wellbeing in school, school climate, school social wellbeing and students’ perceptions of teachers’ wellbeing. Using structural equation modeling, and controlling for SES, we modeled subjective wellbeing as a mediator of the relationship between school-related variables, such as school climate and perception of teacher’s wellbeing, and (a school achievement, and (b school performance. School achievement was computed as a product of (a the probability of passing the school year, and (b the percentage of yearly attendance at school. Data on school achievement was drawn from administrative registries from the Chilean Ministry of Education. School performance was computed as the estimated grade point average (GPA at the end of the school year, based on the students’ previous 5-year GPAs, and was also obtained through administrative data of the last 5 years. Findings reveal the mediating role of subjective wellbeing in the relationship between school-related evaluations (students’ social wellbeing at school, their perception of teachers’ wellbeing and school climate and school achievement. For school achievement, two variables were mediated (students’ social wellbeing at school and school climate. However, for school performance, no significant mediations were found. We conclude that, on the

  14. School Achievement and Performance in Chilean High Schools: The Mediating Role of Subjective Wellbeing in School-Related Evaluations

    Science.gov (United States)

    López, Verónica; Oyanedel, Juan C.; Bilbao, Marian; Torres, Javier; Oyarzún, Denise; Morales, Macarena; Ascorra, Paula; Carrasco, Claudia

    2017-01-01

    School achievement gaps and school failure are problematic issues in Latin America, and are mainly explained by the socio-economic status (SES) of the students. What schools can do to improve school achievement and reduce school failure is a critical issue, both for school management and teacher training. In this study, we present the association of individual and school-related socio-emotional variables with school achievement and performance, controlling for the effects of SES. A probabilistic sample of 4,964 students, drawn from 191 schools enrolled in year 10 in urban areas of Chile, answered questionnaires assessing subjective wellbeing, social wellbeing in school, school climate, school social wellbeing and students’ perceptions of teachers’ wellbeing. Using structural equation modeling, and controlling for SES, we modeled subjective wellbeing as a mediator of the relationship between school-related variables, such as school climate and perception of teacher’s wellbeing, and (a) school achievement, and (b) school performance. School achievement was computed as a product of (a) the probability of passing the school year, and (b) the percentage of yearly attendance at school. Data on school achievement was drawn from administrative registries from the Chilean Ministry of Education. School performance was computed as the estimated grade point average (GPA) at the end of the school year, based on the students’ previous 5-year GPAs, and was also obtained through administrative data of the last 5 years. Findings reveal the mediating role of subjective wellbeing in the relationship between school-related evaluations (students’ social wellbeing at school, their perception of teachers’ wellbeing and school climate) and school achievement. For school achievement, two variables were mediated (students’ social wellbeing at school and school climate). However, for school performance, no significant mediations were found. We conclude that, on the one hand

  15. School Achievement and Performance in Chilean High Schools: The Mediating Role of Subjective Wellbeing in School-Related Evaluations.

    Science.gov (United States)

    López, Verónica; Oyanedel, Juan C; Bilbao, Marian; Torres, Javier; Oyarzún, Denise; Morales, Macarena; Ascorra, Paula; Carrasco, Claudia

    2017-01-01

    School achievement gaps and school failure are problematic issues in Latin America, and are mainly explained by the socio-economic status (SES) of the students. What schools can do to improve school achievement and reduce school failure is a critical issue, both for school management and teacher training. In this study, we present the association of individual and school-related socio-emotional variables with school achievement and performance, controlling for the effects of SES. A probabilistic sample of 4,964 students, drawn from 191 schools enrolled in year 10 in urban areas of Chile, answered questionnaires assessing subjective wellbeing, social wellbeing in school, school climate, school social wellbeing and students' perceptions of teachers' wellbeing. Using structural equation modeling, and controlling for SES, we modeled subjective wellbeing as a mediator of the relationship between school-related variables, such as school climate and perception of teacher's wellbeing, and (a) school achievement, and (b) school performance. School achievement was computed as a product of (a) the probability of passing the school year, and (b) the percentage of yearly attendance at school. Data on school achievement was drawn from administrative registries from the Chilean Ministry of Education. School performance was computed as the estimated grade point average (GPA) at the end of the school year, based on the students' previous 5-year GPAs, and was also obtained through administrative data of the last 5 years. Findings reveal the mediating role of subjective wellbeing in the relationship between school-related evaluations (students' social wellbeing at school, their perception of teachers' wellbeing and school climate) and school achievement. For school achievement, two variables were mediated (students' social wellbeing at school and school climate). However, for school performance, no significant mediations were found. We conclude that, on the one hand, after

  16. Eccentric training for shoulder abductors improves pain, function and isokinetic performance in subjects with shoulder impingement syndrome: a case series.

    Science.gov (United States)

    Camargo, Paula R; Avila, Mariana A; Alburquerque-Sendín, Francisco; Asso, Naoe A; Hashimoto, Larissa H; Salvini, Tania F

    2012-01-01

    Conservative treatments have been proposed for people with shoulder impingement syndrome (SIS), such as strengthening of the rotator cuff and scapular muscles and stretching of the soft tissues of the shoulder. However, there is a lack of studies analyzing the effectiveness of eccentric training in the treatment of SIS. To evaluate the effects of eccentric training for shoulder abductors on pain, function, and isokinetic performance during concentric and eccentric abduction of the shoulder in subjects with SIS. Twenty subjects (7 females, 34.2 SD 10.2 years, 1.7 SD 0.1 m, 78.0 SD 16.3 kg) with unilateral SIS completed the study protocol. Bilateral isokinetic eccentric training at 60º/s for shoulder abductors was performed for six consecutive weeks, twice a week, on alternate days. For each training day, three sets of 10 repetitions were performed with a 3-minute rest period between the sets for each side. The range of motion trained was 60° (ranging from 80° to 20°). The Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire was used to evaluate functional status and symptoms of the upper limbs. Peak torque, total work and acceleration time were measured during concentric and eccentric abduction of the arm at 60º/s and 180º/s using an isokinetic dynamometer. DASH scores, peak torque, total work and acceleration time improved (pshoulder abductors improves physical function of the upper limbs in subjects with SIS.

  17. Trajectories in glycemic control over time are associated with cognitive performance in elderly subjects with type 2 diabetes.

    Science.gov (United States)

    Ravona-Springer, Ramit; Heymann, Anthony; Schmeidler, James; Moshier, Erin; Godbold, James; Sano, Mary; Leroith, Derek; Johnson, Sterling; Preiss, Rachel; Koifman, Keren; Hoffman, Hadas; Silverman, Jeremy M; Beeri, Michal Schnaider

    2014-01-01

    To study the relationships of long-term trajectories of glycemic control with cognitive performance in cognitively normal elderly with type 2 diabetes (T2D). Subjects (n = 835) pertain to a diabetes registry (DR) established in 1998 with an average of 18 HbA1c measurements per subject, permitting identification of distinctive trajectory groups of HbA1c and examining their association with cognitive function in five domains: episodic memory, semantic categorization, attention/working memory, executive function, and overall cognition. Analyses of covariance compared cognitive function among the trajectory groups adjusting for sociodemographic, cardiovascular, diabetes-related covariates and depression. Subjects averaged 72.8 years of age. Six trajectories of HbA1c were identified, characterized by HbA1c level at entry into the DR (Higher/Lower), and trend over time (Stable/Decreasing/Increasing). Both groups with a trajectory of decreasing HbA1c levels had high HbA1c levels at entry into the DR (9.2%, 10.7%), and high, though decreasing, HbA1c levels over time. They had the worst cognitive performance, particularly in overall cognition (pperformed best in cognitive tests. Glycemic control trajectories, which better reflect chronicity of T2D than a single HbA1c measurement, predict cognitive performance. A trajectory of stable HbA1c levels over time is associated with better cognitive function.

  18. Concept mapping improves academic performance in problem solving questions in biochemistry subject.

    Science.gov (United States)

    Baig, Mukhtiar; Tariq, Saba; Rehman, Rehana; Ali, Sobia; Gazzaz, Zohair J

    2016-01-01

    To assess the effectiveness of concept mapping (CM) on the academic performance of medical students' in problem-solving as well as in declarative knowledge questions and their perception regarding CM. The present analytical and questionnaire-based study was carried out at Bahria University Medical and Dental College (BUMDC), Karachi, Pakistan. In this analytical study, students were assessed with problem-solving questions (A-type MCQs), and declarative knowledge questions (short essay questions), and 50% of the questions were from the topics learned by CM. Students also filled a 10-item, 3-point Likert scale questionnaire about their perception regarding the effectiveness of the CM approach, and two open-ended questions were also asked. There was a significant difference in the marks obtained in those problem-solving questions, which were learned by CM as compared to those topics which were taught by the traditional lectures (pstudents' perception regarding CM showed that majority of the students perceive that CM is a helpful technique and it is enjoyed by the students. In open-ended questions, the majority of the students commented positively about the effectiveness of CM. Our results indicate that CM improves academic performance in problem solving but not in declarative knowledge questions. Students' perception about the effectiveness of CM was overwhelmingly positive.

  19. Concept mapping improves academic performance in problem solving questions in biochemistry subject

    Science.gov (United States)

    Baig, Mukhtiar; Tariq, Saba; Rehman, Rehana; Ali, Sobia; Gazzaz, Zohair J

    2016-01-01

    Objective: To assess the effectiveness of concept mapping (CM) on the academic performance of medical students’ in problem-solving as well as in declarative knowledge questions and their perception regarding CM. Methods: The present analytical and questionnaire-based study was carried out at Bahria University Medical and Dental College (BUMDC), Karachi, Pakistan. In this analytical study, students were assessed with problem-solving questions (A-type MCQs), and declarative knowledge questions (short essay questions), and 50% of the questions were from the topics learned by CM. Students also filled a 10-item, 3-point Likert scale questionnaire about their perception regarding the effectiveness of the CM approach, and two open-ended questions were also asked. Results: There was a significant difference in the marks obtained in those problem-solving questions, which were learned by CM as compared to those topics which were taught by the traditional lectures (p<0.001), while no significant difference was observed in marks in declarative knowledge questions (p=0.704). Analysis of students’ perception regarding CM showed that majority of the students perceive that CM is a helpful technique and it is enjoyed by the students. In open-ended questions, the majority of the students commented positively about the effectiveness of CM. Conclusion: Our results indicate that CM improves academic performance in problem solving but not in declarative knowledge questions. Students’ perception about the effectiveness of CM was overwhelmingly positive. PMID:27648017

  20. Performance of dairy cattle subjected to different food strategies during the growing and finishing phases

    Directory of Open Access Journals (Sweden)

    Marcondes Dias de Freitas Neto

    2014-09-01

    Full Text Available The objective of this study was to evaluate the performance of the crossbreed animals, in feedlot, previously fed with different supplemented energetic systems and Brachiaria brizantha pasture. The treatments were: TAA – high level intake of energy during the growing and finishing phases; TAM – high intake of energy during the growing phase and medium intake of energy during of the finishing phase; TMA – medium intake of energy during growing phase and high intake of energy during finishing phase; TMM – medium intake of energy during the growing and finishing phases. During the growth phase the animals received supplementation of 1.0% and 0.5% body weight of animals. In the finishing phase, the animals were fed diets containing 50% of concentrate (medium intake of energy, TDN = 71% or 80% of concentrate (high intake of energy, TDN = 80% in the dry matter of the total diet. The animals of the TAA and TAM treatments had higher average body weight at the beginning of feedlot due to that achieved average slaughter weights of 42 and 21 days less than the other treatments. The animals of the TAA and TAM treatments were more dry matter intake (P 0.05 between treatments for these measures at the end of the termination. The high level of energy supplementation during the growing phase allowed animals to a greater initial weight input in confinement, and consequently, the best performance.

  1. Artificial gait in complete spinal cord injured subjects: how to assess clinical performance

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    Karla Rocha Pithon

    2015-02-01

    Full Text Available Objective Adapt the 6 minutes walking test (6MWT to artificial gait in complete spinal cord injured (SCI patients aided by neuromuscular electrical stimulation. Method Nine male individuals with paraplegia (AIS A participated in this study. Lesion levels varied between T4 and T12 and time post injured from 4 to 13 years. Patients performed 6MWT 1 and 6MWT 2. They used neuromuscular electrical stimulation, and were aided by a walker. The differences between two 6MWT were assessed by using a paired t test. Multiple r-squared was also calculated. Results The 6MWT 1 and 6MWT 2 were not statistically different for heart rate, distance, mean speed and blood pressure. Multiple r-squared (r2 = 0.96 explained 96% of the variation in the distance walked. Conclusion The use of 6MWT in artificial gait towards assessing exercise walking capacity is reproducible and easy to apply. It can be used to assess SCI artificial gait clinical performance.

  2. The grasp2K relativistic atomic structure package

    Science.gov (United States)

    Jönsson, P.; He, X.; Froese Fischer, C.; Grant, I. P.

    2007-10-01

    This paper describes grasp2K, a general-purpose relativistic atomic structure package. It is a modification and extension of the GRASP92 package by [F.A. Parpia, C. Froese Fischer, I.P. Grant, Comput. Phys. Comm. 94 (1996) 249]. For the sake of continuity, two versions are included. Version 1 retains the GRASP92 formats for wave functions and expansion coefficients, but no longer requires preprocessing and more default options have been introduced. Modifications have eliminated some errors, improved the stability, and simplified interactive use. The transition code has been extended to cases where the initial and final states have different orbital sets. Several utility programs have been added. Whereas Version 1 constructs a single interaction matrix for all the J's and parities, Version 2 treats each J and parity as a separate matrix. This block structure results in a reduction of memory use and considerably shorter eigenvectors. Additional tools have been developed for this format. The CPU intensive parts of Version 2 have been parallelized using MPI. The package includes a "make" facility that relies on environment variables. These make it easier to port the application to different platforms. The present version supports the 32-bit Linux and ibmSP environments where the former is compatible with many Unix systems. Descriptions of the features and the program/data flow of the package will be given in some detail in this report. Program summaryProgram title: grasp2K Catalogue identifier: ADZL_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZL_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 213 524 No. of bytes in distributed program, including test data, etc.: 1 328 588 Distribution format: tar.gz Programming language: Fortran and C Computer: Intel

  3. Improved single pellet grasping using automated ad libitum full-time training robot.

    Science.gov (United States)

    Fenrich, Keith K; May, Zacnicte; Hurd, Caitlin; Boychuk, Carolyn E; Kowalczewski, Jan; Bennett, David J; Whishaw, Ian Q; Fouad, Karim

    2015-03-15

    The single pellet grasping (SPG) task is a skilled forelimb motor task commonly used to evaluate reaching and grasp kinematics and recovery of forelimb function in rodent models of CNS injuries and diseases. To train rats in the SPG task, the animals are usually food restricted then placed in an SPG task enclosure and presented food pellets on a platform located beyond a slit located at the front of the task enclosure for 10-30 min, normally every weekday for several weeks. When the SPG task is applied in studies involving various experimental groups, training quickly becomes labor intensive, and can yield results with significant day-to-day variability. Furthermore, training is frequently done during the animals' light-cycle, which for nocturnal rodents such as mice and rats could affect performance. Here we describe an automated pellet presentation (APP) robotic system to train and test rats in the SPG task that reduces some of the procedural weaknesses of manual training. We found that APP trained rats performed significantly more trials per 24 h period, and had higher success rates with less daily and weekly variability than manually trained rats. Moreover, the results show that success rates are positively correlated with the number of dark-cycle trials, suggesting that dark-cycle training has a positive effect on success rates. These results demonstrate that automated training is an effective method for evaluating and training skilled reaching performance of rats, opening up the possibility for new approaches to investigating the role of motor systems in enabling skilled forelimb use and new approaches to investigating rehabilitation following CNS injury. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Interaction between physiological and subjective states predicts the effect of a judging panel on the postures of cellists in performance

    Directory of Open Access Journals (Sweden)

    Satoshi eEndo

    2014-08-01

    Full Text Available This study investigated the effect of a panel of judges on the movements and postures of cellists in performance. 24 expert cellists played a short piece of music, to a metronome beat, in the presence and absence of the panel. Kinematic analyses showed that in the presence of the panel the temporal execution of left arm shifting movements became less variable and closer to the metronome beat. In contrast, the panel's presence had no reliable effect on their spatial accuracy. A detailed postural analysis indicated that left elbow angle during execution of a given high note was correlated with level of heart rate, though the nature of this correlation was systematically affected by the relevant participant's subjective state: if anxious, a higher heart rate correlated with a more flexed elbow, if not anxious then with a more extended elbow. Our results suggest a change in physiological state alone does not reliably predict a change in behaviour in performing cellists, which instead depends on the interaction between physiological state and subjective experience of anxiety. This highlights a need to distinguish performance anxiety from physiological arousal, to which end we advocate currency for the specific term performance arousal to describe heightened physiological activity in a performer.

  5. RADIATION PERFORMANCE OF GAN AND INAS/GAAS QUANTUM DOT BASED DEVICES SUBJECTED TO NEUTRON RADIATION

    Directory of Open Access Journals (Sweden)

    Dhiyauddin Ahmad Fauzi

    2017-05-01

    Full Text Available In addition to their useful optoelectronics functions, gallium nitride (GaN and quantum dots (QDs based structures are also known for their radiation hardness properties. With demands on such semiconductor material structures, it is important to investigate the differences in reliability and radiation hardness properties of these two devices. For this purpose, three sets of GaN light-emitting diode (LED and InAs/GaAs dot-in-a well (DWELL samples were irradiated with thermal neutron of fluence ranging from 3×1013 to 6×1014 neutron/cm2 in PUSPATI TRIGA research reactor. The radiation performances for each device were evaluated based on the current-voltage (I-V and capacitance-voltage (C-V electrical characterisation method. Results suggested that the GaN based sample is less susceptible to electrical changes due to the thermal neutron radiation effects compared to the QD based sample.

  6. Performance of asphaltic concrete incorporating styrene butadiene rubber subjected to varying aging condition

    Science.gov (United States)

    Salah, Faisal Mohammed; Jaya, Ramadhansyah Putra; Mohamed, Azman; Hassan, Norhidayah Abdul; Rosni, Nurul Najihah Mad; Mohamed, Abdullahi Ali; Agussabti

    2017-12-01

    The influence of styrene butadiene rubber (SBR) on asphaltic concrete properties at different aging conditions was presented in this study. These aging conditions were named as un-aged, short-term, and long-term aging. The conventional asphalt binder of penetration grade 60/70 was used in this work. Four different levels of SBR addition were employed (i.e., 0 %, 1 %, 3 %, and 5 % by binder weight). Asphalt concrete mixes were prepared at selected optimum asphalt content (5 %). The performance was evaluated based on Marshall Stability, resilient modulus, and dynamic creep tests. Results indicated the improving stability and permanent deformation characteristics that the mixes modified with SBR polymer have under aging conditions. The result also showed that the stability, resilient modulus, and dynamic creep tests have the highest rates compared to the short-term aging and un-aged samples. Thus, the use of 5 % SBR can produce more durable asphalt concrete mixtures with better serviceability.

  7. Effects of team-based learning on perceived teamwork and academic performance in a health assessment subject.

    Science.gov (United States)

    Park, Hyung-Ran; Kim, Chun-Ja; Park, Jee-Won; Park, Eunyoung

    2015-01-01

    The purpose of this study was to examine the effectiveness of team-based learning (a well-recognized learning and teaching strategy), applied in a health assessment subject, on nursing students' perceived teamwork (team-efficacy and team skills) and academic performance (individual and team readiness assurance tests, and examination scores). A prospective, one-group, pre- and post-test design enrolled a convenience sample of 74 second-year nursing students at a university in Suwon, Korea. Team-based learning was applied in a 2-credit health assessment subject over a 16-week semester. All students received written material one week before each class for readiness preparation. After administering individual- and team-readiness assurance tests consecutively, the subject instructor gave immediate feedback and delivered a mini-lecture to the students. Finally, students carried out skill based application exercises. The findings showed significant improvements in the mean scores of students' perceived teamwork after the introduction of team-based learning. In addition, team-efficacy was associated with team-adaptability skills and team-interpersonal skills. Regarding academic performance, team readiness assurance tests were significantly higher than individual readiness assurance tests over time. Individual readiness assurance tests were significantly related with examination scores, while team readiness assurance tests were correlated with team-efficacy and team-interpersonal skills. The application of team-based learning in a health assessment subject can enhance students' perceived teamwork and academic performance. This finding suggests that team-based learning may be an effective learning and teaching strategy for improving team-work of nursing students, who need to collaborate and effectively communicate with health care providers to improve patients' health.

  8. 'It's quite hard to grasp the enormity of it': perceived needs of people upon diagnosis of rheumatoid arthritis.

    Science.gov (United States)

    Radford, S; Carr, M; Hehir, M; Davis, B; Robertson, L; Cockshott, Z; Tipler, S; Hewlett, S

    2008-09-01

    The diagnosis of rheumatoid arthritis (RA) brings rapid pharmacological and multidisciplinary team interventions to address inflammatory processes and symptom management. However, people may also need support on the journey to self-management. The aim of this study was to explore what professional support patients feel they receive upon diagnosis, and what support they feel would be most helpful. Two focus groups comprised patients with at least five years'; disease duration (n = 7), and patients more recently diagnosed (5-18 months, n = 5). The latter had attended at least two appointments in a rheumatology nurse specialist clinic during the previous year, aimed at providing support upon diagnosis. Transcripts were subjected to thematic analysis to identify common issues regarding support needs, which were then grouped into themes. Interviewing and analysis was performed by researchers not involved in clinical care. Four overarching themes emerged. 'Information' was needed about the symptoms of RA, its management and personal outcome, while 'Support' related to emotional needs ('It's quite hard to grasp the enormity of it'). Information and Support overlapped, in that patients wanted someone to talk to, and to be listened to. These two themes were underpinned by issues of service delivery: 'Choice' (patient or professional to talk to, groups, one-to-one) and 'Involvement' (holistic care, partnership), which overlapped in terms of the opportunity to decide when and which interventions to access. People with RA report not only informational, but also emotional support needs at diagnosis. The potential for delivering emotional support to patients around the time of diagnosis warrants further exploration. (c) 2008 John Wiley & Sons, Ltd.

  9. The effect of subjective awareness measures on performance in artificial grammar learning task.

    Science.gov (United States)

    Ivanchei, Ivan I; Moroshkina, Nadezhda V

    2018-01-01

    Systematic research into implicit learning requires well-developed awareness-measurement techniques. Recently, trial-by-trial measures have been widely used. However, they can increase complexity of a study because they are an additional experimental variable. We tested the effects of these measures on performance in artificial grammar learning study. Four groups of participants were assigned to different awareness measures conditions: confidence ratings, post-decision wagering, decision strategy attribution or none. Decision-strategy-attribution participants demonstrated better grammar learning and longer response times compared to controls. They also exhibited a conservative bias. Grammaticality by itself was a stronger predictor of strings endorsement in decision-strategy-attribution group compared to other groups. Confidence ratings and post-decision wagering only affected the response times. These results were supported by an additional experiment that used a balanced chunk strength design. We conclude that a decision-strategy-attribution procedure may force participants to adopt an analytical decision-making strategy and rely mostly on conscious knowledge of artificial grammar. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. PERFORMANCE-RELIABILITY – THE MAIN SUBJECT OF THE BANKING ANALYSIS OF THE CREDITED SOCIETIES

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    AVRAM (BOITOŞ CAMELIA

    2013-12-01

    Full Text Available Since the crediting activity occupies the primary role in any banking institution, the necessity of study and its analysis is required by following some steps both at a microeconomic level and at a macroeconomic one. Going over the theme, which aims at the importance of a thorough study of the clients' reliability for highlighting the existing risks in the banking activity in general, and particularly in the crediting activity, becomes as more interesting as their approach at the level of the member states of the European Union tends towards a common theme. Starting from these premises, we have considered as being extremely important the selection of a research theme which aims at the risks in the crediting activity, emphasizing the analysis of the clients' reliability both in the decision of crediting in order to assume the risk of credit and in determining the financial and banking performances. Being given the complexity of the existing risks in the banking activity in general and particularly of the credit risk, the clients' reliability represents an extremely important field, of research and application, bearing in mind both the actual stage of developing the Romanian banking system and the attempts of its alignment to the requirements imposed by the European Union.

  11. Performance Evaluation of Submerged Floating Tunnel Subjected to Hydrodynamic and Seismic Excitations

    Directory of Open Access Journals (Sweden)

    Naik Muhammad

    2017-10-01

    Full Text Available Submerged floating tunnels (SFTs are innovative structural solutions to waterway crossings, such as sea-straits, fjords and lakes. As the width and depth of straits increase, the conventional structures such as cable-supported bridges, underground tunnels or immersed tunnels become uneconomical alternatives. For the realization of SFT, the structural response under extreme environmental conditions needs to be evaluated properly. This study evaluates the displacements and internal forces of SFT under hydrodynamic and three-dimensional seismic excitations to check the global performance of an SFT in order to conclude on the optimum design. The formulations incorporate modeling of ocean waves, currents and mooring cables. The SFT responses were evaluated using three different mooring cable arrangements to determine the stability of the mooring configuration, and the most promising configuration was then used for further investigations. A comparison of static, hydrodynamic and seismic response envelope curves of the SFT is provided to determine the dominant structural response. The study produces useful conclusions regarding the structural behavior of the SFT using a three-dimensional numerical model.

  12. Electromechanical performance of induction motor/drive systems subjected to voltage sags

    Science.gov (United States)

    Tunaboylu, Serdar N.

    Induction Motors are workhorses for many industries. They are extensively utilized in industrial variable-frequency drive (VFD) or adjustable-speed drive (ASD) applications as well as constant speed applications. Recent advances in power electronics have made AC motor drives an economically viable solution for ASD applications traditionally dominated by dc motor drives. In this study, electromechanical performance variables of an Induction Motor (IM) have been studied during the balanced voltage sags. For this purpose a laboratory prototype of an industrial mixer has been designed. IM has been coupled to a speed reducer that is worm gear type with a ratio 10 to 1. Then the reducer is vertically coupled to a food process mixer within a metal canister. The mixer represents a high friction load with practically zero inertia. Voltage, current, speed, and power measurements have been collected and compared with the simulation results from Simnon. An open-loop control Volts per Hertz boost strategy has been used in order to compensate the speed loss during the three-phase balanced voltage sags. Both compensated and uncompensated cases have been run and compared with simulation results. Results are verified with a reasonably good agreement that the total system modeling is successful and boost compensation circuit is effective.

  13. Assessment of Mechanical Properties and Damage of High Performance Concrete Subjected to Magnesium Sulfate Environment

    Directory of Open Access Journals (Sweden)

    Sheng Cang

    2017-01-01

    Full Text Available Sulfate attack is one of the most important problems affecting concrete structures, especially magnesium sulfate attack. This paper presents an investigation on the mechanical properties and damage evolution of high performance concrete (HPC with different contents of fly ash exposure to magnesium sulfate environment. The microstructure, porosity, mass loss, dimensional variation, compressive strength, and splitting tensile strength of HPC were investigated at various erosion times up to 392 days. The ultrasonic pulse velocity (UPV propagation in HPC at different erosion time was determined by using ultrasonic testing technique. A relationship between damage and UPV of HPC was derived according to damage mechanics, and a correlation between the damage of HPC and erosion time was obtained eventually. The results indicated that (1 the average increasing amplitude of porosity for HPCs was 34.01% before and after exposure to magnesium sulfate solution; (2 the damage evolution of HPCs under sulfate attack could be described by an exponential fitting; (3 HPC containing 20% fly ash had the strongest resistance to magnesium sulfate attack.

  14. Differences in performance on the functional movement screen between chronic low back pain patients and healthy control subjects.

    Science.gov (United States)

    Ko, Min-Joo; Noh, Kyung-Hee; Kang, Min-Hyeok; Oh, Jae-Seop

    2016-07-01

    [Purpose] Differences in scores on the Functional Movement Screen between patients with chronic lower back pain and healthy control subjects were investigated. [Subjects and Methods] In all, 20 chronic lower back pain patients and 20 healthy control subjects were recruited. Chronic lower back pain patients and healthy controls performed the Functional Movement Screen (deep squat, hurdle step, inline lunge, shoulder mobility, active straight leg raise, trunk stability pushup, and rotary stability). The Mann-Whitney test was used to analyze differences in Functional Movement Screen scores between the two groups. [Results] Chronic lower back pain patients scored lower on the Functional Movement Screen total composite compared with healthy control subjects. Chronic lower back pain patients scored lower on Functional Movement Screen subtests including the deep squat, hurdle step, active straight leg raise, and rotary stability tests. [Conclusion] The deep squat, hurdle step, active straight leg raise, and rotary stability tasks of the Functional Movement Screen can be recommended as a functional assessment tools to identify functional deficits in chronic lower back pain patients.

  15. Cortical control of object-specific grasp relies on adjustments of both activity and effective connectivity

    DEFF Research Database (Denmark)

    Tia, Banty; Takemi, Mitsuaki; Kosugi, Akito

    2017-01-01

    The cortical mechanisms of grasping have been extensively studied in macaques and humans. Here, we investigated whether common marmosets could rely on similar mechanisms despite striking differences in manual dexterity. Two common marmosets were trained to grasp-and-pull three objects eliciting d...

  16. The effect of food properties on grasping and manipulation in the aquatic frog, Xenopus laevis.

    Science.gov (United States)

    Anzeraey, Aude; Aumont, Madeleine; Decamps, Thierry; Herrel, Anthony; Pouydebat, Emmanuelle

    2017-10-05

    The ability to grasp an object is fundamental from an evolutionary perspective. Involved in many daily activities, grasping has been extensively studied in primates and other mammals. Yet, other groups of tetrapods, including anurans, have also evolved significant forelimb prehensile capacities that are often thought to have originated in an arboreal context. However, grasping is also observed in aquatic species. Yet, how aquatic frogs use their forelimbs to capture and manipulate prey remains largely unknown. The aim of this study is to explore how the grasping and manipulation of food items in aquatic frogs is impacted by food properties such as size and mobility. To do so we use the aquatic frog Xenopus laevis and quantified the use of the hands and fingers while processing mobile and stationary prey of different sizes (small, intermediate, and large prey). Our results show that X. laevis is able to individualize the digits and that the mobility and the length of the prey significantly influence the kind of grasping pattern used. Grasping abilities are thus not specific to terrestrial, nor arboreal species. These results illustrate how prey properties impact grasping and manipulation strategies in an aquatic frog and shed further light on the ecological contexts that may have given rise to the origin of grasping in frogs. © 2017. Published by The Company of Biologists Ltd.

  17. Kinematic rules for upper and lower arm contributions to grasp orientation

    NARCIS (Netherlands)

    Marotta, J.J.; Medendorp, W.P.; Crawford, J.D.

    2003-01-01

    The purpose of the current study was to investigate the contribution of upper and lower arm torsion to grasp orientation during a reaching and grasping movement. In particular, we examined how the visuomotor system deals with the conflicting demands of coordinating upper and lower arm torsion and

  18. Fast grasping of unknown objects using cylinder searching on a single point cloud

    NARCIS (Netherlands)

    Lei, Q.; Wisse, M.; Verikas, Antanas; Radeva, Petia; Nikolaev, Dmitry P.; Zhang, Wei; Zhou, Jianhong

    2017-01-01

    Grasping of unknown objects with neither appearance data nor object models given in advance is very important for robots that work in an unfamiliar environment. The goal of this paper is to quickly synthesize an executable grasp for one unknown object by using cylinder searching on a single point

  19. Development of Reaching and Grasping skills in infants with Down syndrome

    NARCIS (Netherlands)

    de Campos, A.C.; Rocha, N.A.C.F.; Savelsbergh, G.J.P.

    2010-01-01

    Reaching and grasping skills have been described to emerge from a dynamic interaction between intrinsic and extrinsic factors. The aims of the study were to investigate the effect of such intrinsic factors as age and Down syndrome on the development of reaching and grasping skills and on overall

  20. Managing distributed dynamic systems with spatial grasp technology

    CERN Document Server

    Sapaty, Peter Simon

    2017-01-01

    The book describes a novel ideology and supporting information technology for integral management of both civil and defence-orientated large, distributed dynamic systems. The approach is based on a high-level Spatial Grasp Language, SGL, expressing solutions in physical, virtual, executive and combined environments in the form of active self-evolving and self-propagating patterns spatially matching the systems to be created, modified and controlled. The communicating interpreters of SGL can be installed in key system points, which may be in large numbers (up to millions and billions) and represent equipped humans, robots, laptops, smartphones, smart sensors, etc. Operating under gestalt-inspired scenarios in SGL initially injected from any points, these systems can be effectively converted into goal-driven spatial machines (rather than computers as dealing with physical matter too) capable of responding to numerous challenges caused by growing world dynamics in the 21st century. Including numerous practical e...

  1. Quantification of intestinal bacteria, operating cost and performance of fingerlings Nile tilapia subjected to probiotics

    Directory of Open Access Journals (Sweden)

    Nilton Garcia-Marengoni

    2015-05-01

    Full Text Available The use of microorganisms of the genus Bacillus in aquaculture is a nutritional management practice that is rapidly expanding in regions with intensive fish farming. This study aimed to quantify the total bacteria and total coliforms from the intestinal microbiota and estimate the partial operating costs and growth performance of Nile tilapia (Oreochromis niloticus of the GIFT strain. A total of 1,200 post-larvae (24.7 ± 0.50 mg were distributed into 24 aquaria (0.03-m³ capacity within a completely randomized design in 2 x 3 factorial (phase x bacteria, with four replications. Each aquarium, containing 50 post-larvae (sex reversal phase or 30 fish (fingerlings phase, it was considered to be an experimental unit, consisting of three treatments (diet+Bacillus subtilis C-3102, diet+Bacillus cereus var. toyoi and diet without probiotic addition. The quantification of the total bacteria and total coliforms of the intestinal microbiota of tilapia were influenced (P 0.05 by adding probiotics in the diets and no effect of the interaction between phase and bacteria was observed. The weight gain, average daily weight gain, specific growth rate and apparent feed conversion were not affected (P > 0.05 by inclusion of probiotics as part of the diets. The inclusion of B. subtilis and B. cereus as part of diets for Nile tilapia promotes intestinal colonization and improves the survival rate without negatively influencing the feed intake, total biomass, gross revenue and partial operating costs and net revenue. Therefore it recommends the use of these probiotics to growth of tilapia fingerlings Nile, GIFT strain.

  2. Cognitive performance and the thymus among HIV-infected subjects receiving HAART

    Directory of Open Access Journals (Sweden)

    Maria J Miguez-Burbano

    2008-06-01

    Full Text Available Maria J Miguez-Burbano1, John E Lewis2, Jose Moreno3, Joel Fishman41Robert Stempel School of Public Health & School of Medicine, Florida International University, Miami, FL, USA; 2Department of Psychiatry and Behavioral Sciences, 3Department of Medicine, 4Department of Radiology, University of Miami Miller School of Medicine, Miami, FL, USAObjective: To evaluate the impact of alcohol use, which is widespread in human immunodeficiency virus (HIV+ individuals, on highly active antiretroviral therapy (HAART-associated immune and cognitive improvements and the relationship between those two responses.Methods: In a case-control longitudinal study, thymic volume, cognition, and immune responses were evaluated at baseline and after 6 months therapy in HIV+ and HIV- controls. Cognitive performance was evaluated using the HIV Dementia Score (HDS and the California Verbal Learning Test (CVLT.Results: Prior to HAART, thymic volume varied considerably from 2.7 to 29.3 cm3 (11 ± 7.2 cm3. Thymic volume at baseline showed a significantly inverse correlation with the patient’s number of years of drinking (r2 = 0.207; p < 0.01, as well as HDS and the CVLT scores in both HIV-infected (r2 = 0.37, p = 0.03 and noninfected (r2 = 0.8, p = 0.01. HIV-infected individuals with a small thymic volume scored in the demented range, as compared with those with a larger thymus (7 ± 2.7 vs. 12 ± 2.3, p = 0.005. After HAART, light/moderate drinkers exhibited thymus size twice that of heavy drinkers (14.8 ± 10.4 vs. 6.9 ± 3.3 cm3.Conclusions: HAART-associated increases of thymus volume appear to be negatively affected by alcohol consumption and significantly related to their cognitive status. This result could have important clinical implications.Keywords: thymus, CNS, immune, alcohol

  3. Quantitative performance of E-Scribe warehouse in detecting quality issues with digital annotated ECG data from healthy subjects.

    Science.gov (United States)

    Sarapa, Nenad; Mortara, Justin L; Brown, Barry D; Isola, Lamberto; Badilini, Fabio

    2008-05-01

    The US Food and Drug Administration recommends submission of digital electrocardiograms in the standard HL7 XML format into the electrocardiogram warehouse to support preapproval review of new drug applications. The Food and Drug Administration scrutinizes electrocardiogram quality by viewing the annotated waveforms and scoring electrocardiogram quality by the warehouse algorithms. Part of the Food and Drug Administration warehouse is commercially available to sponsors as the E-Scribe Warehouse. The authors tested the performance of E-Scribe Warehouse algorithms by quantifying electrocardiogram acquisition quality, adherence to QT annotation protocol, and T-wave signal strength in 2 data sets: "reference" (104 digital electrocardiograms from a phase I study with sotalol in 26 healthy subjects with QT annotations by computer-assisted manual adjustment) and "test" (the same electrocardiograms with an intentionally introduced predefined number of quality issues). The E-Scribe Warehouse correctly detected differences between the 2 sets expected from the number and pattern of errors in the "test" set (except for 1 subject with QT misannotated in different leads of serial electrocardiograms) and confirmed the absence of differences where none was expected. E-Scribe Warehouse scores below the threshold value identified individual electrocardiograms with questionable T-wave signal strength. The E-Scribe Warehouse showed satisfactory performance in detecting electrocardiogram quality issues that may impair reliability of QTc assessment in clinical trials in healthy subjects.

  4. Reach and grasp by people with tetraplegia using a neurally controlled robotic arm.

    Science.gov (United States)

    Hochberg, Leigh R; Bacher, Daniel; Jarosiewicz, Beata; Masse, Nicolas Y; Simeral, John D; Vogel, Joern; Haddadin, Sami; Liu, Jie; Cash, Sydney S; van der Smagt, Patrick; Donoghue, John P

    2012-05-16

    Paralysis following spinal cord injury, brainstem stroke, amyotrophic lateral sclerosis and other disorders can disconnect the brain from the body, eliminating the ability to perform volitional movements. A neural interface system could restore mobility and independence for people with paralysis by translating neuronal activity directly into control signals for assistive devices. We have previously shown that people with long-standing tetraplegia can use a neural interface system to move and click a computer cursor and to control physical devices. Able-bodied monkeys have used a neural interface system to control a robotic arm, but it is unknown whether people with profound upper extremity paralysis or limb loss could use cortical neuronal ensemble signals to direct useful arm actions. Here we demonstrate the ability of two people with long-standing tetraplegia to use neural interface system-based control of a robotic arm to perform three-dimensional reach and grasp movements. Participants controlled the arm and hand over a broad space without explicit training, using signals decoded from a small, local population of motor cortex (MI) neurons recorded from a 96-channel microelectrode array. One of the study participants, implanted with the sensor 5 years earlier, also used a robotic arm to drink coffee from a bottle. Although robotic reach and grasp actions were not as fast or accurate as those of an able-bodied person, our results demonstrate the feasibility for people with tetraplegia, years after injury to the central nervous system, to recreate useful multidimensional control of complex devices directly from a small sample of neural signals.

  5. Grasping and Placing Operation for Labware Transportation in Life Science Laboratories using Mobile Robots

    Directory of Open Access Journals (Sweden)

    Mohammed Myasar Ali

    2017-07-01

    Full Text Available In automated working environments, mobile robots can be used for different purposes such as material handling, domestic services, and objects transportation. This work presents a grasping and placing operation for multiple labware and tube racks in life science laboratories using the H20 mobile robots. The H20 robot has dual arms where each arm consists of 6 revolute joints with 6-DOF and 2-DOF grippers. The labware, which have to be manipulated and transported, contain chemical and biological components. Therefore, an accurate approach for object recognition and position estimation is required. The recognition and pose estimation of the desired objects are very essential to guide the robotic arm in the manipulation tasks. In this work, the problem statement of H20 transportation system with the proposed methodology are presented. Different strategies (visual and non-visual of labware manipulation using mobile robots are described. The H20 robot is equipped with a Kinect V2 sensor to identify and estimate the position of the target. The local features recognition based on SURF algorithm (Speeded-Up Robust Features is used. The recognition process is performed for the required labware and holder to perform the grasping and placing operation. A strategy is proposed to find the required holder and to check its emptiness for the placing tasks. Different styles of grippers and labware containers are used to manipulate different weights of labware and to realize a safe transportation. The parts of mobile robot transportation system are communicated with each other using Asynchronous socket Channels.

  6. Cognitive Performance in Subjects With Multiple Sclerosis Is Robustly Influenced by Gender in Canonical-Correlation Analysis.

    Science.gov (United States)

    Lin, Sue-Jin; Lam, Janet; Beveridge, Samantha; Vavasour, Irene; Traboulsee, Anthony; Li, David K B; MacKay, Alex; McKeown, Martin; Kosaka, Brenda

    2017-01-01

    The authors explored the relations between clinical/demographic characteristics and performance on a neuropsychological battery (eight tests) in a cohort (N=46) of multiple sclerosis (MS) subjects. Findings resulted from a secondary analysis of a study examining the relationships between imaging biomarkers in MS and cognitive tasks of executive functioning. The objective was to determine whether the overlapping test results could be judiciously combined and associated with clinical/demographic variables. Canonical-correlation analysis (CCA) was utilized, and it was found that differences between performance on untimed tests, and the sum of performance on timed Trail-Making Tests, Parts A and B, best matched clinical/demographic variables, and gender was the most important feature.

  7. Virtual Control of Prosthetic Hand Based on Grasping Patterns and Estimated Force from Semg

    Directory of Open Access Journals (Sweden)

    Zhu Gao-Ke

    2016-01-01

    Full Text Available Myoelectric prosthetic hands aim to serve upper limb amputees. The myoelectric control of the hand grasp action is a kind of real-time or online method. Thus it is of great necessity to carry on a study of online prosthetic hand electrical control. In this paper, the strategy of simultaneous EMG decoding of grasping patterns and grasping force was realized by controlling a virtual multi-degree-freedom prosthetic hand and a real one-degree-freedom prosthetic hand simultaneously. The former realized the grasping patterns from the recognition of the sEMG pattern. The other implemented the grasping force from sEMG force decoding. The results show that the control method is effective and feasible.

  8. A Grasp-Pose Generation Method Based on Gaussian Mixture Models

    Directory of Open Access Journals (Sweden)

    Wenjia Wu

    2015-11-01

    Full Text Available A Gaussian Mixture Model (GMM-based grasp-pose generation method is proposed in this paper. Through offline training, the GMM is set up and used to depict the distribution of the robot's reachable orientations. By dividing the robot's workspace into small 3D voxels and training the GMM for each voxel, a look-up table covering all the workspace is built with the x, y and z positions as the index and the GMM as the entry. Through the definition of Task Space Regions (TSR, an object's feasible grasp poses are expressed as a continuous region. With the GMM, grasp poses can be preferentially sampled from regions with high reachability probabilities in the online grasp-planning stage. The GMM can also be used as a preliminary judgement of a grasp pose's reachability. Experiments on both a simulated and a real robot show the superiority of our method over the existing method.

  9. Do aging and dual-tasking impair the capacity to store and retrieve visuospatial information needed to guide perturbation-evoked reach-to-grasp reactions?

    Directory of Open Access Journals (Sweden)

    Kenneth C Cheng

    Full Text Available A recent study involving young adults showed that rapid perturbation-evoked reach-to-grasp balance-recovery reactions can be guided successfully with visuospatial-information (VSI retained in memory despite: 1 a reduction in endpoint accuracy due to recall-delay (time between visual occlusion and perturbation-onset, PO and 2 slowing of the reaction when performing a concurrent cognitive task during the recall-delay interval. The present study aimed to determine whether this capacity is compromised by effects of aging. Ten healthy older adults were tested with the previous protocol and compared with the previously-tested young adults. Reactions to recover balance by grasping a small handhold were evoked by unpredictable antero-posterior platform-translation (barriers deterred stepping reactions, while using liquid-crystal goggles to occlude vision post-PO and for varying recall-delay times (0-10 s prior to PO (the handhold was moved unpredictably to one of four locations 2 s prior to vision-occlusion. Subjects also performed a spatial- or non-spatial-memory cognitive task during the delay-time in a subset of trials. Results showed that older adults had slower reactions than the young across all experimental conditions. Both age groups showed similar reduction in medio-lateral end-point accuracy when recall-delay was longest (10 s, but differed in the effect of recall delay on vertical hand elevation. For both age groups, engaging in either the non-spatial or spatial-memory task had similar (slowing effects on the arm reactions; however, the older adults also showed a dual-task interference effect (poorer cognitive-task performance that was specific to the spatial-memory task. This provides new evidence that spatial working memory plays a role in the control of perturbation-evoked balance-recovery reactions. The delays in completing the reaction that occurred when performing either cognitive task suggest that such dual-task situations in daily

  10. The effects of receiver placement on probe microphone, performance, and subjective measures with open canal hearing instruments.

    Science.gov (United States)

    Alworth, Lynzee N; Plyler, Patrick N; Reber, Monika Bertges; Johnstone, Patti M

    2010-04-01

    Open canal hearing instruments differ in method of sound delivery to the ear canal, distance between the microphone and the receiver, and physical size of the devices. Moreover, RITA (receiver in the aid) and RITE (receiver in the ear) hearing instruments may also differ in terms of retention and comfort as well as ease of use and care for certain individuals. What remains unclear, however, is if any or all of the abovementioned factors contribute to hearing aid outcome. To determine the effect of receiver location on performance and/or preference of listeners using open canal hearing instruments. An experimental study in which subjects were exposed to a repeated measures design. Twenty-five adult listeners with mild sloping to moderately severe sensorineural hearing loss (mean age 67 yr). Participants completed two six-week trial periods for each device type. Probe microphone, objective, and subjective measures (quiet, noise) were conducted unaided and aided at the end of each trial period. Occlusion effect results were not significantly different between the RITA and RITE instruments; however, frequency range was extended in the RITE instruments, resulting in significantly greater maximum gain for the RITE instruments than the RITA instruments at 4000 and 6000 Hz. Objective performance in quiet or in noise was unaffected by receiver location. Subjective measures revealed significantly greater satisfaction ratings for the RITE than for the RITA instruments. Similarly, preference in quiet and overall preference were significantly greater for the RITE than for the RITA instruments. Although no occlusion differences were noted between instruments, the RITE did demonstrate a significant difference in reserve gain before feedback at 4000 and 6000 Hz. Objectively; no positive benefit was noted between unaided and aided conditions on speech recognition tests. These results suggest that such testing may not be sensitive enough to determine aided benefit with open canal

  11. Grasping neurons of monkey parietal and premotor cortices encode action goals at distinct levels of abstraction during complex action sequences

    National Research Council Canada - National Science Library

    Bonini, Luca; Serventi, Francesca Ugolotti; Simone, Luciano; Rozzi, Stefano; Ferrari, Pier Francesco; Fogassi, Leonardo

    2011-01-01

    ...), chained together to attain the final action goal. Previous studies have shown that grasping neurons of parietal area PFG and premotor area F5 can code the goal of simple actions in which grasping is embedded...

  12. Effects of three therapeutic doses of codeine/paracetamol on driving performance, a psychomotor vigilance test, and subjective feelings.

    Science.gov (United States)

    Amato, Jean-Noël; Marie, Sullivan; Lelong-Boulouard, Véronique; Paillet-Loilier, Magalie; Berthelon, Catherine; Coquerel, Antoine; Denise, Pierre; Bocca, Marie-Laure

    2013-07-01

    Some recent pharmacoepidemiological studies revealed an elevated risk of driving accidents after opioid analgesics uses. Among analgesics, codeine is often associated with paracetamol in numerous pharmaceutical specialties. The objective of this study was to evaluate the dose-effect relationship of three usual therapeutic doses of codeine/paracetamol on driving ability, psychomotor performance, subjective alertness, in link with blood concentrations in healthy young volunteers. Driving performance, responses to psychomotor vigilance tests, and scales reflecting alertness were evaluated during the morning after drug intake in a double-blind, randomized, placebo-controlled study. Sixteen healthy volunteers (23.4 ± 2.7 years old, 8 men and 8 women) participated in this balanced, cross-over study. Three doses of codeine/paracetamol (20/400, 40/800, 60/1200 mg) were evaluated against placebo. Two blood samples were collected, 1 and 4 h after drug intake. In serum, codeine and morphine concentrations were determined in serum using high-performance liquid chromatography electrospray ionization-tandem mass spectrometry, and paracetamol concentrations using fluorescence polarization immunoassay. Driving and psychomotor performance were not affected by any of the three codeine/paracetamol doses. However, significant, though modest, correlations were observed between the driving parameters and both morphine and codeine blood concentrations. This study did not reveal any significant impairment in performance due to the three therapeutic doses used in healthy young volunteers. However, the relationships between drug blood concentration and behavioral measures suggest that an inter-subject variability in blood concentration may influence the power of the observed drug effect.

  13. A Comparison of Robotic Simulation Performance on Basic Virtual Reality Skills: Simulator Subjective Versus Objective Assessment Tools.

    Science.gov (United States)

    Dubin, Ariel K; Smith, Roger; Julian, Danielle; Tanaka, Alyssa; Mattingly, Patricia

    2017-07-27

    To answer the question of whether there is a difference between robotic virtual reality simulator performance assessment and validated human reviewers. Current surgical education relies heavily on simulation. Several assessment tools are available to the trainee, including the actual robotic simulator assessment metrics and the Global Evaluative Assessment of Robotic Skills (GEARS) metrics, both of which have been independently validated. GEARS is a rating scale through which human evaluators can score trainees' performances on 6 domains: depth perception, bimanual dexterity, efficiency, force sensitivity, autonomy, and robotic control. Each domain is scored on a 5-point Likert scale with anchors. We used 2 common robotic simulators, the dV-Trainer (dVT; Mimic Technologies Inc., Seattle, WA) and the da Vinci Skills Simulator (dVSS; Intuitive Surgical, Sunnyvale, CA), to compare the performance metrics of robotic surgical simulators with the GEARS for a basic robotic task on each simulator. A prospective single-blinded randomized study. A surgical education and training center. Surgeons and surgeons in training. Demographic information was collected including sex, age, level of training, specialty, and previous surgical and simulator experience. Subjects performed 2 trials of ring and rail 1 (RR1) on each of the 2 simulators (dVSS and dVT) after undergoing randomization and warm-up exercises. The second RR1 trial simulator performance was recorded, and the deidentified videos were sent to human reviewers using GEARS. Eight different simulator assessment metrics were identified and paired with a similar performance metric in the GEARS tool. The GEARS evaluation scores and simulator assessment scores were paired and a Spearman rho calculated for their level of correlation. Seventy-four subjects were enrolled in this randomized study with 9 subjects excluded for missing or incomplete data. There was a strong correlation between the GEARS score and the simulator metric

  14. Principal components of hand kinematics and neurophysiological signals in motor cortex during reach to grasp movements.

    Science.gov (United States)

    Mollazadeh, Mohsen; Aggarwal, Vikram; Thakor, Nitish V; Schieber, Marc H

    2014-10-15

    A few kinematic synergies identified by principal component analysis (PCA) account for most of the variance in the coordinated joint rotations of the fingers and wrist used for a wide variety of hand movements. To examine the possibility that motor cortex might control the hand through such synergies, we collected simultaneous kinematic and neurophysiological data from monkeys performing a reach-to-grasp task. We used PCA, jPCA and isomap to extract kinematic synergies from 18 joint angles in the fingers and wrist and analyzed the relationships of both single-unit and multiunit spike recordings, as well as local field potentials (LFPs), to these synergies. For most spike recordings, the maximal absolute cross-correlations of firing rates were somewhat stronger with an individual joint angle than with any principal component (PC), any jPC or any isomap dimension. In decoding analyses, where spikes and LFP power in the 100- to 170-Hz band each provided better decoding than other LFP-based signals, the first PC was decoded as well as the best decoded joint angle. But the remaining PCs and jPCs were predicted with lower accuracy than individual joint angles. Although PCs, jPCs or isomap dimensions might provide a more parsimonious description of kinematics, our findings indicate that the kinematic synergies identified with these techniques are not represented in motor cortex more strongly than the original joint angles. We suggest that the motor cortex might act to sculpt the synergies generated by subcortical centers, superimposing an ability to individuate finger movements and adapt the hand to grasp a wide variety of objects. Copyright © 2014 the American Physiological Society.

  15. The granularity of grasping. Comment on "Grasping synergies: A motor-control approach to the mirror neuron mechanism" by A. D'Ausilio et al.

    Science.gov (United States)

    Hamilton, Antonia F. de C.

    2015-03-01

    The idea that mirror neuron systems in the human and the macaque monkey could provide a link between perceiving an action and performing it has spurred intense research [1,2]. Hundreds of papers now examine if this link exists and what it might contribute to human behaviour. The review article from D'Ausilio et al. [3] highlights how relatively few papers have considered the granularity of coding with mirror neuron systems, and even fewer have directly tested different possibilities. Granularity refers to the critical question of what actually is encoded within the mirror system - are neurons selective for low level kinematic features such as joint angle, or for postural synergies, or for action goals? Focusing on studies of single neurons in macaques and on studies measuring the excitability of primary motor cortex with TMS, the review suggests that it is very hard to distinguish low-level kinematic from goal representations. Furthermore, these two levels are often highly correlated in real-life contexts - the kinematics needed to grasp an apple are defined by the shape of the goal (an apple tends to be a large sphere) and these kinematics differ for other possible goals (a pencil which is a narrow cylinder). In some cases, kinematics may be enough to define a goal [4]. The review suggests that it is therefore arbitrary to distinguish these levels, and that a synergy level might be a better way to understand the mirror system. Synergies are a form of coding based on commonly used hand-shapes or hand postures, which take into account the fact that some joint angles are more likely to co-occur than others. Evidence that different grasp shapes are represented separately in premotor cortex has been found [5]. These could provide an intermediate level of representation between muscle activity and goals. The review proposes that a synergy level of granularity provides the best way to consider both the motor system and the role of the mirror system in understanding

  16. Towards a standardized grasping and refuelling on-orbit servicing for geo spacecraft

    Science.gov (United States)

    Medina, Alberto; Tomassini, Angelo; Suatoni, Matteo; Avilés, Marcos; Solway, Nick; Coxhill, Ian; Paraskevas, Iosif S.; Rekleitis, Georgios; Papadopoulos, Evangelos; Krenn, Rainer; Brito, André; Sabbatinelli, Beatrice; Wollenhaupt, Birk; Vidal, Christian; Aziz, Sarmad; Visentin, Gianfranco

    2017-05-01

    Exploitation of space must benefit from the latest advances in robotics. On-orbit servicing is a clear candidate for the application of autonomous rendezvous and docking mechanisms. However, during the last three decades most of the trials took place combining extravehicular activities (EVAs) with telemanipulated robotic arms. The European Space Agency (ESA) considers that grasping and refuelling are promising near-mid-term capabilities that could be performed by servicing spacecraft. Minimal add-ons on spacecraft to enhance their serviceability may protect them for a changing future in which satellite servicing may become mainstream. ESA aims to conceive and promote standard refuelling provisions that can be installed in present and future European commercial geostationary orbit (GEO) satellite platforms and scientific spacecraft. For this purpose ESA has started the ASSIST activity addressing the analysis, design and validation of internal provisions (such as modifications to fuel, gas, electrical and data architecture to allow servicing) and external provisions (such as integrated berthing fixtures with peripheral electrical, gas, liquid connectors, leak check systems and corresponding optical and radio markers for cooperative rendezvous and docking). This refuelling approach is being agreed with European industry (OHB, Thales Alenia Space) and expected to be consolidated with European commercial operators as a first step to become an international standard; this approach is also being considered for on-orbit servicing spacecraft, such as the SpaceTug, by Airbus DS. This paper describes in detail the operational means, structure, geometry and accommodation of the system. Internal and external provisions will be designed with the minimum possible impact on the current architecture of GEO satellites without introducing additional risks in the development and commissioning of the satellite. End-effector and berthing fixtures are being designed in the range of few

  17. When does stress help or harm? The effects of stress controllability and subjective stress response on stroop performance.

    Science.gov (United States)

    Henderson, Roselinde K; Snyder, Hannah R; Gupta, Tina; Banich, Marie T

    2012-01-01

    The ability to engage in goal-directed behavior despite exposure to stress is critical to resilience. Questions of how stress can impair or improve behavioral functioning are important in diverse settings, from athletic competitions to academic testing. Previous research suggests that controllability is a key factor in the impact of stress on behavior: learning how to control stressors buffers people from the negative effects of stress on subsequent cognitively demanding tasks. In addition, research suggests that the impact of stress on cognitive functioning depends on an individual's response to stressors: moderate responses to stress can lead to improved performance while extreme (high or low) responses can lead to impaired performance. The present studies tested the hypothesis that (1) learning to behaviorally control stressors leads to improved performance on a test of general executive functioning, the color-word Stroop, and that (2) this improvement emerges specifically for people who report moderate (subjective) responses to stress. Experiment 1: Stroop performance, measured before and after a stress manipulation, was compared across groups of undergraduate participants (n = 109). People who learned to control a noise stressor and received accurate performance feedback demonstrated reduced Stroop interference compared with people exposed to uncontrollable noise stress and feedback indicating an exaggerated rate of failure. In the group who learned behavioral control, those who reported moderate levels of stress showed the greatest reduction in Stroop interference. In contrast, in the group exposed to uncontrollable events, self-reported stress failed to predict performance. Experiment 2: In a second sample (n = 90), we specifically investigated the role of controllability by keeping the rate of failure feedback constant across groups. In the group who learned behavioral control, those who reported moderate levels of stress showed the greatest Stroop

  18. Performance evaluation method of electric energy data acquire system based on combination of subjective and objective weights

    Science.gov (United States)

    Gao, Chen; Ding, Zhongan; Deng, Bofa; Yan, Shengteng

    2017-10-01

    According to the characteristics of electric energy data acquire system (EEDAS), considering the availability of each index data and the connection between the index integrity, establishing the performance evaluation index system of electric energy data acquire system from three aspects as master station system, communication channel, terminal equipment. To determine the comprehensive weight of each index based on triangular fuzzy number analytic hierarchy process with entropy weight method, and both subjective preference and objective attribute are taken into consideration, thus realize the performance comprehensive evaluation more reasonable and reliable. Example analysis shows that, by combination with analytic hierarchy process (AHP) and triangle fuzzy numbers (TFN) to establish comprehensive index evaluation system based on entropy method, the evaluation results not only convenient and practical, but also more objective and accurate.

  19. Subjectivation and Performative Politics--Butler Thinking Althusser and Foucault: Intelligibility, Agency and the Raced-Nationed-Religioned Subjects of Education

    Science.gov (United States)

    Youdell, Deborah

    2006-01-01

    Judith Butler is perhaps best known for her take-up of the debate between Derrida and Austin over the function of the performative and her subsequent suggestion that the subject be understood as performatively constituted. Another important but less often noted move within Butler's consideration of the processes through which the subject is…

  20. Distraction and task engagement: How interesting and boring information impact driving performance and subjective and physiological responses.

    Science.gov (United States)

    Horrey, William J; Lesch, Mary F; Garabet, Angela; Simmons, Lucinda; Maikala, Rammohan

    2017-01-01

    As more devices and services are integrated into vehicles, drivers face new opportunities to perform additional tasks while driving. While many studies have explored the detrimental effects of varying task demands on driving performance, there has been little attention devoted to tasks that vary in terms of personal interest or investment-a quality we liken to the concept of task engagement. The purpose of this study was to explore the impact of task engagement on driving performance, subjective appraisals of performance and workload, and various physiological measurements. In this study, 31 participants (M = 37 yrs) completed three driving conditions in a driving simulator: listening to boring auditory material; listening to interesting material; and driving with no auditory material. Drivers were simultaneously monitored using near-infrared spectroscopy, heart monitoring and eye tracking systems. Drivers exhibited less variability in lane keeping and headway maintenance for both auditory conditions; however, response times to critical braking events were longer in the interesting audio condition. Drivers also perceived the interesting material to be less demanding and less complex, although the material was objectively matched for difficulty. Drivers showed a reduced concentration of cerebral oxygenated hemoglobin when listening to interesting material, compared to baseline and boring conditions, yet they exhibited superior recognition for this material. The practical implications, from a safety standpoint, are discussed. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. Static Stability Analysis of a Planar Object Grasped by Multifingers with Three Joints

    Directory of Open Access Journals (Sweden)

    Takayoshi Yamada

    2015-11-01

    Full Text Available This paper discusses static stability of a planar object grasped by multifingers with three joints. Each individual joint (prismatic joint or revolute joint is modeled as a linear spring stiffness. The object mass and the link masses are also included. We consider not only pure rolling contact but also frictionless sliding contact. The grasp stability is investigated using the potential energy method. This paper makes the following contributions: (i Grasp wrench vectors and grasp stiffness matrices are analytically derived not only for the rolling contact but also for the sliding contact; (ii It is shown in detail that the vectors and the matrices are given by functions of grasp parameters such as the contact conditions (rolling contact and sliding contact, the contact position, the contact force, the local curvature, the link shape, the object mass, the link masses, and so on; (iii By using positive definiteness of the difference matrix of the grasp stiffness matrices, it is analytically proved that the rolling contact grasp is more stable than the sliding contact grasp. The displacement direction affected by the contact condition deviation is derived; (iv By using positive definiteness of the differential matrix with respect to the local curvatures, it is analytically proved that the grasp stability increases when the local curvatures decrease. The displacement direction affected by the local curvature deviation is also derived; (v Effects of the object mass and the joint positions are discussed using numerical examples. The numerical results are reinforced by analytical explanations. The effect of the link masses is also investigated.

  2. Comparison of the perceived subjective exertion and total load lifted response in resistance exercises performed on stable and unstable platforms

    Directory of Open Access Journals (Sweden)

    Liliane Cunha Aranda

    2015-03-01

    Full Text Available This study aimed to compare the perceived subjective exertion (PSE and total load lifted in resistance exercises performed on stable platforms (SP and unstable platforms (UP. Participants were 20 men (24.6 ± 3.4 years, 179 ± 0.1 cm, 80.6 ± 9.1 kg and 11.8 ± 3.4% fat. Each subject performed a 15 maximum repetition test in half squat exercises (soil and balance discs, pronated barbell row (soil and bosu and biceps curl (soil and balance discs in both conditions. PSE was measured using the OMNI-RES scale and the load lifted value (kg. To verify the normality of data, the Shapiro-Wilk test was used. Possible differences related to loads and PSE on the platforms were performed by the paired t test. Significance level of p <0.05 was adopted. No significant differences between PSE values on SP and UP were respectively observed in the half squat (8.2 and 8.5 / p = 0.8, pronated barbell row (8.4 and 8.4 / p = 0.7 and biceps curl (8.6 and 8.7 / p = 1.0. Higher load values on SP and UP were respectively found in half squat (83.9kg and 70.3kg / p <0.001 and pronated barbell row exercises (53.2kg and 48.6kg / p = 0.01 on SP. However, biceps curl showed dissimilar behavior (48.2kg and 47.4kg / p = 0.5. It was concluded that UP does not promote differences in PSE responses even working with smaller load or similar load.

  3. When does stress help or harm? The effects of stress controllability and subjective stress response on Stroop performance.

    Directory of Open Access Journals (Sweden)

    Roselinde Kaiser Henderson

    2012-06-01

    Full Text Available The ability to engage in goal-directed behavior despite exposure to stress is critical to resilience. Questions of how stress can impair or improve behavioral functioning are important in diverse settings, from athletic competitions to academic testing to clinical therapy. Previous research suggests that controllability is a key factor in the impact of stress on behavior: learning how to control stressors buffers people from the negative effects of stress on subsequent cognitively demanding tasks. In addition, research suggests that the impact of stress on cognitive functioning depends on an individual’s response to stressors: moderate responses to stress can lead to improved performance while extreme (high or low responses can lead to impaired performance. The present studies tested the hypothesis that 1 learning to behaviorally control stressors leads to improved performance on a test of general executive functioning, the color-word Stroop, and that 2 this improvement emerges specifically for people who report moderate (subjective responses to stress. Experiment 1: Stroop performance, measured before and after a stress manipulation, was compared across groups of undergraduate participants (n=109. People who learned to control a noise stressor and received accurate performance feedback demonstrated reduced Stroop interference compared with people exposed to uncontrollable noise stress and feedback indicating an exaggerated rate of failure. In the group who learned behavioral control, those who reported moderate levels of stress showed the greatest reduction in Stroop interference. In contrast, in the group exposed to uncontrollable events, self-reported stress failed to predict performance. Experiment 2: In a second sample (n=90, we specifically investigated the role of controllability by keeping the rate of failure feedback constant across groups. In the group who learned behavioral control, those who reported moderate levels of stress

  4. Learning to grasp efficiently: the development of motor planning and the role of observational learning.

    Science.gov (United States)

    Jovanovic, Bianca; Schwarzer, Gudrun

    2011-04-22

    We examined whether 18-, 24-, and 42-month-old children, like adults, prospectively adjust their hand movements to insure a comfortable hand posture at the endpoint, and whether children can learn to grasp efficiently by observation. The task required grasping a bar and fitting it into a hollow cylinder in order to make it light up. Measures of quantitative (grip height), as well as qualitative (grip type) prospective grip adaptation were analyzed. Grip height adaptation was found reliably by 24 months, grip type adaptation by 3 years. The ability to learn efficient grasping by observation seems however very restricted. Copyright © 2010 Elsevier Ltd. All rights reserved.

  5. Virtual Control of Prosthetic Hand Based on Grasping Patterns and Estimated Force from Semg

    OpenAIRE

    Zhu Gao-Ke; Xu Li-Sha; Zhang Yi; Deng Hua

    2016-01-01

    Myoelectric prosthetic hands aim to serve upper limb amputees. The myoelectric control of the hand grasp action is a kind of real-time or online method. Thus it is of great necessity to carry on a study of online prosthetic hand electrical control. In this paper, the strategy of simultaneous EMG decoding of grasping patterns and grasping force was realized by controlling a virtual multi-degree-freedom prosthetic hand and a real one-degree-freedom prosthetic hand simultaneously. The former rea...

  6. Playing With Nonverbal Communication: Using Grasp and Facial Direction to Create Adaptive Interaction in a Game

    DEFF Research Database (Denmark)

    Mortensen, Ditte Hvas; Bærentsen, Klaus B.

    2014-01-01

    We examine the use of automatic adaptation to the user’s grasp and facial direction in interaction with a game. Two experimental studies were conducted. The first experiment identified patterns in grasp and facial direction that can be used as objective indicators of intentions and attention....... In the second experiment, we used the patterns identified in experiment 1 to create a game that adapted to grasp and facial direction. We compared two adaptive games to a purely command-based game. The results show that the participants in the adaptive versions of the game were significantly faster and made...

  7. VisGraB: A Benchmark for Vision-Based Grasping. Paladyn Journal of Behavioral Robotics

    DEFF Research Database (Denmark)

    Kootstra, Gert; Popovic, Mila; Jørgensen, Jimmy Alison

    2012-01-01

    We present a database and a software tool, VisGraB, for benchmarking of methods for vision-based grasping of unknown objects with no prior object knowledge. The benchmark is a combined real-world and simulated experimental setup. Stereo images of real scenes containing several objects in different...... that a large number of grasps can be executed and evaluated while dealing with dynamics and the noise and uncertainty present in the real world images. VisGraB enables a fair comparison among different grasping methods. The user furthermore does not need to deal with robot hardware, focusing on the vision...

  8. Subsystems of sensory attention for skilled reaching: vision for transport and pre-shaping and somatosensation for grasping, withdrawal and release.

    Science.gov (United States)

    Sacrey, Lori-Ann R; Whishaw, Ian Q

    2012-06-01

    Skilled reaching is a forelimb movement in which a subject reaches for a piece of food that is placed in the mouth for eating. It is a natural movement used by many animal species and is a routine, daily activity for humans. Its prominent features include transport of the hand to a target, shaping the digits in preparation for grasping, grasping, and withdrawal of the hand to place the food in the mouth. Studies on normal human adults show that skilled reaching is mediated by at least two sensory attention processes. Hand transport to the target and hand shaping are temporally coupled with visual fixation on the target. Grasping, withdrawal, and placing the food into the mouth are associated with visual disengagement and somatosensory guidance. Studies on nonhuman animal species illustrate that shared visual and somatosensory attention likely evolved in the primate lineage. Studies on developing infants illustrate that shared attention requires both experience and maturation. Studies on subjects with Parkinson's disease and Huntington's disease illustrate that decomposition of shared attention also features compensatory visual guidance. The evolutionary, developmental, and neural control of skilled reaching suggests that associative learning processes are importantly related to normal adult attention sharing and so can be used in remediation. The economical use of sensory attention in the different phases of skilled reaching ensures efficiency in eating, reduces sensory interference between sensory reference frames, and provides efficient neural control of the advance and withdrawal components of skilled reaching movements. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Evaluation of reach and grasp robot-assisted therapy suggests similar functional recovery patterns on proximal and distal arm segments in sub-acute hemiplegia.

    Science.gov (United States)

    Loureiro, Rui C V; Harwin, William S; Lamperd, Robert; Collin, Christine

    2014-05-01

    This paper provides some additional evidence in support of the hypothesis that robot therapies are clinically beneficial in neurorehabilitation. Although only four subjects were included in the study, the design of the intervention and the measures were done so as to minimize bias. The results are presented as single case studies, and can only be interpreted as such due to the study size. The intensity of intervention was 16 h and the therapy philosophy (based on Carr and Shepherd) was that coordinated movements are preferable to joint based therapies, and that coordinating distal movements (in this case grasps) helps not only to recover function in these areas, but has greater value since the results are immediately transferable to daily skills such as reach and grasp movements.

  10. Subjective Perception of Sports Performance, Training, Sleep and Dietary Patterns of Malaysian Junior Muslim Athletes during Ramadan Intermittent Fasting.

    Science.gov (United States)

    Singh, Rabindarjeet; Hwa, Ooi Cheong; Roy, Jolly; Jin, Chai Wen; Ismail, Siti Musyrifah; Lan, Mohamad Faizal; Hiong, Loo Lean; Aziz, Abdul-Rashid

    2011-09-01

    To examine the subjective perception of daily acute fasting on sports performance, training, sleep and dietary patterns of Muslim athletes during the Ramadan month. Seven hundred and thirty-four (411 male and 323 female) Malaysian Junior-level Muslim athletes (mean age 16.3 ± 2.6 y) participated in the survey which was designed to establish the personal perception of their sport performance, sleep pattern, food and fluid intake during Ramadan fasting. The survey was conducted during and immediately after the month of Ramadan in 2009. Twenty-four percent of the athletes perceived that there was an adverse effect of the Ramadan fast on their sporting performance and 29.3% reported that quality of training during Ramadan was also negatively influenced. Majority (48.2%) of the athletes stated that Ramadan fasting did not affect their normal sleep pattern but 66.6% of them complained of sleepiness during the daytime. Half of the athletes (41.4%) maintained the caloric intake during Ramadan as they normally would with the majority of them (76.2%) reporting that they consumed more fluids during Ramadan. Overall, Malaysian Junior-level Muslim athletes showed diverse views in their perception of changes in their training, sleep and dietary patterns during Ramadan fast. These individual differences probably indicate differences in the athletes' adaptability and coping strategies during fasting and training in Ramadan.

  11. Electrically evoked and voluntary maximal isometric tension in relation to dynamic muscle performance in elderly male subjects, aged 69 years.

    Science.gov (United States)

    Davies, C T; White, M J; Young, K

    1983-01-01

    The dynamic performance and electrically evoked mechanical properties of elderly triceps surae muscle have been investigated in 9 men, aged 69 yr. Dynamic performance consisted of cycling on a force bicycle and a vertical jump off two feet from a force platform. The results showed that the time to peak tension (TPT) and half relaxation time (1/2 RT) were significantly greater (p less than 0.001) by 30 ms and 22 ms and the supramaximal twitch (Pt) and tetanic (20 Hz-P020) tensions and maximal voluntary contraction (MVC) were less by 45 N (-33%), 708 N (-49%), and 899 N (-43%) in the elderly compared with young male control subjects. On the force platform, the height jumped (Ht), maximal force exerted (P), take-off velocity (VT), net impulse (NI) and peak power output (W) were less by 18.6 cm, 173 N, 0.9 ms-1, 52 Ns and 1120 w respectively. Similar differences of power, force and velocity were observed on the force bicycle. The reduction of W in the elderly was associated with the contractile characteristics of the leg muscle. The loss of contractile speed and capacity to to generate force in old people was reflected in their inability to develop power during the performance of a maximal vertical jump and cycling.

  12. Subjective Perception of Sports Performance, Training, Sleep and Dietary Patterns of Malaysian Junior Muslim Athletes during Ramadan Intermittent Fasting

    Science.gov (United States)

    Singh, Rabindarjeet; Hwa, Ooi Cheong; Roy, Jolly; Jin, Chai Wen; Ismail, Siti Musyrifah; Lan, Mohamad Faizal; Hiong, Loo Lean; Aziz, Abdul-Rashid

    2011-01-01

    Purpose To examine the subjective perception of daily acute fasting on sports performance, training, sleep and dietary patterns of Muslim athletes during the Ramadan month. Methods Seven hundred and thirty-four (411 male and 323 female) Malaysian Junior-level Muslim athletes (mean age 16.3 ± 2.6 y) participated in the survey which was designed to establish the personal perception of their sport performance, sleep pattern, food and fluid intake during Ramadan fasting. The survey was conducted during and immediately after the month of Ramadan in 2009. Results Twenty-four percent of the athletes perceived that there was an adverse effect of the Ramadan fast on their sporting performance and 29.3% reported that quality of training during Ramadan was also negatively influenced. Majority (48.2%) of the athletes stated that Ramadan fasting did not affect their normal sleep pattern but 66.6% of them complained of sleepiness during the daytime. Half of the athletes (41.4%) maintained the caloric intake during Ramadan as they normally would with the majority of them (76.2%) reporting that they consumed more fluids during Ramadan. Conclusions Overall, Malaysian Junior-level Muslim athletes showed diverse views in their perception of changes in their training, sleep and dietary patterns during Ramadan fast. These individual differences probably indicate differences in the athletes’ adaptability and coping strategies during fasting and training in Ramadan. PMID:22375236

  13. “How many sums can I do”? Performative strategies and diffractive thinking as methodological tools for rethinking mathematical subjectivity

    Directory of Open Access Journals (Sweden)

    Anna Palmer

    2011-12-01

    Full Text Available The aim of this article is to illustrate how the understanding of mathematical subjectivity changes when transiting theoretically and methodologically from a discursive and performative thinking, as suggested by Judith Butler (1990, 1993, 1997, to an agential realist and diffractive thinking, inspired by Karen Barad’s theories (2007, 2008. To show this I have examined narrative memory stories about mathematics written by students participating in Teacher Education maths courses. I provide examples of such stories and present an in-depth analysis of one such story. The first part of the analysis has been carried out using performative methodological strategies – in relation to Judith Butler’s theories – while the latter part of analysis has been performed with the aid of diffractive methodological thinking – in relation to Barad’s theoretical perspectives. When summarising the different analyses, it becomes evident that the understanding of data – and of me as researcher – changes when transiting from one theoretical and methodological arena to another. Depending on which questions we pose, what methodological strategies we use, and which theoretical fields we get involved in, we would see and understand this differently.

  14. Performance Evaluation of Waterproofing Membrane Systems Subject to the Concrete Joint Load Behavior of Below-Grade Concrete Structures

    Directory of Open Access Journals (Sweden)

    Jaeyoung Song

    2017-11-01

    Full Text Available Below-grade structures such as parking lots, underground subway tunnels, and basements are growing in scale and reaching deeper below-ground levels. In this type of environment, they become subject to higher water pressure. The concrete material of the structures is exposed to wet conditions for longer periods of time, which makes the proper adhesion of waterproofing membranes difficult. Joint movements from increased structural settlement, thermal expansion/shrinkage, and physical loads from external sources (e.g., vehicles make securing durable waterproofing challenging. While ASTM Guides, Korean Codes, and BS Practice Codes on below-grade waterproofing stress the importance of manufacturer specification for quality control, ensuring high quality waterproofing for the ever-changing scale of construction remains a challenge. This study proposes a new evaluation method and criteria which allow for the selection of waterproofing membranes based on specific performance attributes and workmanship. It subjects six different waterproofing membrane systems (installed on dry and wet surface conditioned mortar slab specimens with an artificial joint to different cyclic movement widths to 300 cycles in water to demonstrate that inadequate material properties and workmanship are key causes for leakages.

  15. Neurocognitive performance, subjective well-being, and psychosocial functioning after benzodiazepine withdrawal in patients with schizophrenia or bipolar disorder

    DEFF Research Database (Denmark)

    Baandrup, Lone; Fagerlund, Birgitte; Glenthoj, Birte

    2017-01-01

    Chronic benzodiazepine use is common in patients with mental illness and is associated with cognitive impairment. It is unclear whether benzodiazepine-induced cognitive impairment is reversible. Amelioration of cognitive dysfunction may be facilitated during benzodiazepine tapering by add......-on melatonin due to its anti-inflammatory and neuroprotective properties. We examined how melatonin and benzodiazepine withdrawal affect cognition, subjective well-being, and psychosocial functioning. Eighty patients with schizophrenia or bipolar disorder were randomized to add-on treatment once daily...... with either prolonged-release melatonin or placebo in a 24-week, double-blind clinical trial. All participants gradually tapered usual benzodiazepine dosage in a closely monitored treatment setting. We used the Brief Assessment of Cognition in Schizophrenia (BACS) to assess neurocognitive performance...

  16. Structure of the Membrane-tethering GRASP Domain Reveals a Unique PDZ Ligand Interaction That Mediates Golgi Biogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Truschel, S.T.; Heroux, A.; Sengupta, D.; Foote, A.; Macbeth, M. R.; Linstedt, A. D.

    2011-06-10

    Biogenesis of the ribbon-like membrane network of the mammalian Golgi requires membrane tethering by the conserved GRASP domain in GRASP65 and GRASP55, yet the tethering mechanism is not fully understood. Here, we report the crystal structure of the GRASP55 GRASP domain, which revealed an unusual arrangement of two tandem PDZ folds that more closely resemble prokaryotic PDZ domains. Biochemical and functional data indicated that the interaction between the ligand-binding pocket of PDZ1 and an internal ligand on PDZ2 mediates the GRASP self-interaction, and structural analyses suggest that this occurs via a unique mode of internal PDZ ligand recognition. Our data uncover the structural basis for ligand specificity and provide insight into the mechanism of GRASP-dependent membrane tethering of analogous Golgi cisternae.

  17. Structure of the Membrane-tethering GRASP Domain Reveals a Unique PDZ Ligand Interaction That Mediates Golgi Biogenesis

    Energy Technology Data Exchange (ETDEWEB)

    S Truschel; D Sengupta; A Foote; A Heroux; M Macbeth; A Linstedt

    2011-12-31

    Biogenesis of the ribbon-like membrane network of the mammalian Golgi requires membrane tethering by the conserved GRASP domain in GRASP65 and GRASP55, yet the tethering mechanism is not fully understood. Here, we report the crystal structure of the GRASP55 GRASP domain, which revealed an unusual arrangement of two tandem PDZ folds that more closely resemble prokaryotic PDZ domains. Biochemical and functional data indicated that the interaction between the ligand-binding pocket of PDZ1 and an internal ligand on PDZ2 mediates the GRASP self-interaction, and structural analyses suggest that this occurs via a unique mode of internal PDZ ligand recognition. Our data uncover the structural basis for ligand specificity and provide insight into the mechanism of GRASP-dependent membrane tethering of analogous Golgi cisternae.

  18. Holding-on: co-evolution between infant carrying and grasping behaviour in strepsirrhines.

    Science.gov (United States)

    Peckre, Louise; Fabre, Anne-Claire; Wall, Christine E; Brewer, David; Ehmke, Erin; Haring, David; Shaw, Erin; Welser, Kay; Pouydebat, Emmanuelle

    2016-11-24

    The origin and evolution of manual grasping remain poorly understood. The ability to cling requires important grasping abilities and is essential to survive in species where the young are carried in the fur. A previous study has suggested that this behaviour could be a pre-adaptation for the evolution of fine manipulative skills. In this study we tested the co-evolution between infant carrying in the fur and manual grasping abilities in the context of food manipulation. As strepsirrhines vary in the way infants are carried (mouth vs. fur), they are an excellent model to test this hypothesis. Data on food manipulation behaviour were collected for 21 species of strepsirrhines. Our results show that fur-carrying species exhibited significantly more frequent manual grasping of food items. This study clearly illustrates the potential novel insights that a behaviour (infant carrying) that has previously been largely ignored in the discussion of the evolution of primate manipulation can bring.

  19. Action perception in infancy: the plasticity of 7-month-olds' attention to grasping actions.

    Science.gov (United States)

    Daum, Moritz M; Wronski, Caroline; Harms, Annekatrin; Gredebäck, Gustaf

    2016-09-01

    The present study investigates the plasticity of 7-month-old infants' orienting of attention during their perception of grasping actions. Previous research has shown that when infants observe a grasping hand, they shift their attention in line with the grasping direction, which is indicated by a reliable priming effect in this direction. The mechanisms behind this priming effect are largely unknown, and it is unclear how malleable this priming effect is with respect to a brief exposure to novel action-target contingencies. In a spatial-cueing paradigm, we presented a series of training trials prior to a series of test trials. These training sequences significantly modulated infants' attention. This suggests that action perception, when assessed through shifts of attention, is not solely based on the infants' grasping experience but quickly adapts to context-specific observed regularities.

  20. E-GRASP/Eratosthenes: a mission proposal for millimetric TRF realization

    Science.gov (United States)

    Biancale, Richard; Pollet, Arnaud; Coulot, David; Mandea, Mioara

    2017-04-01

    The ITRF is currently worked out by independent concatenation of space technique information. GNSS, DORIS, SLR and VLBI data are processed independently by analysis centers before combination centers form mono-technique sets which are then combined together to produce official ITRF solutions. Actually this approach performs quite well, although systematisms between techniques remain visible in origin or scale parameters of the underlying terrestrial frames, for instance. Improvement and homogenization of TRF are expected in the future, provided that dedicated multi-technique platforms are used at best. The goal fixed by GGOS to realizing the terrestrial reference system with an accuracy of 1 mm and a long-term stability of 0.1 mm/yr can be next achieved in the E-GRASP/Eratosthenes scenario. This mission proposed to ESA as response of the 2017 Earth Explorer-9 call was already scientifically well assessed in the 2016 EE9 call. It co-locates all of the fundamental space-based geodetic instruments, GNSS and DORIS receivers, laser retro-reflectors, and a VLBI transmitter on the same satellite platform on a highly eccentric orbit with particular attention paid to the time and space metrology on board. Different kinds of simulations were performed both for discriminating the best orbital scenario according to many geometric/technical/physical criteria and for assessing the expected performances on the TRF according to GGOS goals. The presentation will focus on the mission scenario and simulation results.

  1. Effects of zeolite supplementation on parameters of intestinal barrier integrity, inflammation, redoxbiology and performance in aerobically trained subjects.

    Science.gov (United States)

    Lamprecht, Manfred; Bogner, Simon; Steinbauer, Kurt; Schuetz, Burkhard; Greilberger, Joachim F; Leber, Bettina; Wagner, Bernhard; Zinser, Erwin; Petek, Thomas; Wallner-Liebmann, Sandra; Oberwinkler, Tanja; Bachl, Norbert; Schippinger, Gert

    2015-01-01

    Zeolites are crystalline compounds with microporous structures of Si-tetrahedrons. In the gut, these silicates could act as adsorbents, ion-exchangers, catalysts, detergents or anti-diarrheic agents. This study evaluated whether zeolite supplementation affects biomarkers of intestinal wall permeability and parameters of oxidation and inflammation in aerobically trained individuals, and whether it could improve their performance. In a randomized, double-blinded, placebo controlled trial, 52 endurance trained men and women, similar in body fat, non-smokers, 20-50 years, received 1.85 g of zeolite per day for 12 weeks. Stool samples for determination of intestinal wall integrity biomarkers were collected. From blood, markers of redox biology, inflammation, and DNA damage were determined at the beginning and the end of the study. In addition, VO2max and maximum performance were evaluated at baseline and after 12 weeks of treatment. For statistical analyses a 2-factor ANOVA was used. At baseline both groups showed slightly increased stool zonulin concentrations above normal. After 12 weeks with zeolite zonulin was significantly (p zeolite group. There were no significant changes observed in the other measured parameters. Twelve weeks of zeolite supplementation exerted beneficial effects on intestinal wall integrity as indicated via decreased concentrations of the tight junction modulator zonulin. This was accompanied by mild anti-inflammatory effects in this cohort of aerobically trained subjects. Further research is needed to explore mechanistic explanations for the observations in this study.

  2. Measuring cognitive load during simulation-based psychomotor skills training: sensitivity of secondary-task performance and subjective ratings.

    Science.gov (United States)

    Haji, Faizal A; Khan, Rabia; Regehr, Glenn; Drake, James; de Ribaupierre, Sandrine; Dubrowski, Adam

    2015-12-01

    As interest in applying cognitive load theory (CLT) to the study and design of pedagogic and technological approaches in healthcare simulation grows, suitable measures of cognitive load (CL) are needed. Here, we report a two-phased study investigating the sensitivity of subjective ratings of mental effort (SRME) and secondary-task performance (signal detection rate, SDR and recognition reaction time, RRT) as measures of CL. In phase 1 of the study, novice learners and expert surgeons attempted a visual-monitoring task under two conditions: single-task (monitoring a virtual patient's heart-rate) and dual-task (tying surgical knots on a bench-top simulator while monitoring the virtual patient's heart-rate). Novices demonstrated higher mental effort and inferior secondary-task performance on the dual-task compared to experts (RRT 1.76 vs. 0.73, p = 0.012; SDR 0.27 vs. 0.97, p instructional design research are discussed.

  3. How academic career and habits related to the school environment influence on academic performance in the physical education subject

    Directory of Open Access Journals (Sweden)

    Vizuete Carrizosa, Manuel

    2012-01-01

    Full Text Available The main objective of this study was to analyze the degree of influence of some school habits and scholar trayectory on academic achievement in physical education (PE students in secondary education (ESO in the city of Badajoz. A total sample of 1197 students in compulsory secondary education 49.9% men, and 50.1% women, participated in the study. They spent a questionnaire filled out by the river questions about major school habits, of which eight variables were analyzed also included the final course in the subject of EF as a variable for analysis of academic performance. Through statistical analysis with ANOVA, Mann-Whitney U, and Kruskal Wallis H, there are significant differences in PE scores in all variables analyzed (p d».001, among which being repetitive, being truant, the time to read and study daily. In the variable environment perceived in class, there is a degree of significance (p d».05. Pupils who were repeaters, missing more classes or were delayed more times than read and studied less and earned a worse environment in their classes, are those who obtained poorer performance on EF.

  4. Objective and subjective evaluation of the performance of medical contact lenses fitted using a contact lens selection algorithm.

    Science.gov (United States)

    Visser, Esther-Simone; Wisse, Robert P L; Soeters, Nienke; Imhof, Saskia M; Van der Lelij, Allegonda

    2016-08-01

    To evaluate the performance of medical contact lenses (CLs) for a wide range of clinical indications. Prospective cross-sectional study. A total of 281 eyes were evaluated in 281 consecutive patients (≥18 years of age; CL use ≥3 months) who visited the contact lens service in a tertiary academic clinic for a scheduled follow-up visit. The main outcome measured were clinical indications for CL wear; CL type; change in corrected distance visual acuity (CDVA) with CL use; CL wearing duration; CL wearing time; subjective performance measured using a visual analog scale (VAS) questionnaire (score range: 0-100); and effectiveness of the lens-selection algorithm. Wearing CLs significantly improved CDVA compared to wearing spectacles (median change: -0.15 logMAR, range: 1.00 to -2.10; Plenses and users of soft lenses. These results underscore the importance of prescribing scleral lenses and the need for tertiary eye clinics to offer patients a variety of CL types. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  5. GRASP1 Regulates Synaptic Plasticity and Learning through Endosomal Recycling of AMPA Receptors.

    Science.gov (United States)

    Chiu, Shu-Ling; Diering, Graham Hugh; Ye, Bing; Takamiya, Kogo; Chen, Chih-Ming; Jiang, Yuwu; Niranjan, Tejasvi; Schwartz, Charles E; Wang, Tao; Huganir, Richard L

    2017-03-22

    Learning depends on experience-dependent modification of synaptic efficacy and neuronal connectivity in the brain. We provide direct evidence for physiological roles of the recycling endosome protein GRASP1 in glutamatergic synapse function and animal behavior. Mice lacking GRASP1 showed abnormal excitatory synapse number, synaptic plasticity, and hippocampal-dependent learning and memory due to a failure in learning-induced synaptic AMPAR incorporation. We identified two GRASP1 point mutations from intellectual disability (ID) patients that showed convergent disruptive effects on AMPAR recycling and glutamate uncaging-induced structural and functional plasticity. Wild-type GRASP1, but not ID mutants, rescued spine loss in hippocampal CA1 neurons in Grasp1 knockout mice. Together, these results demonstrate a requirement for normal recycling endosome function in AMPAR-dependent synaptic function and neuronal connectivity in vivo, and suggest a potential role for GRASP1 in the pathophysiology of human cognitive disorders. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Corrections in Grasp Posture in Response to Modifications of Action Goals

    Science.gov (United States)

    Hughes, Charmayne M. L.; Seegelke, Christian; Spiegel, Marnie Ann; Oehmichen, Corinna; Hammes, Julia; Schack, Thomas

    2012-01-01

    There is ample evidence that people plan their movements to ensure comfortable final grasp postures at the end of a movement. The end-state comfort effect has been found to be a robust constraint during unimanual movements, and leads to the inference that goal-postures are represented and planned prior to movement initiation. The purpose of this study was to examine whether individuals make appropriate corrections to ensure comfortable final goal postures when faced with an unexpected change in action goal. Participants reached for a horizontal cylinder and placed the left or right end of the object into the target disk. As soon as the participant began to move, a secondary stimuli was triggered, which indicated whether the intended action goal had changed or not. Confirming previous research, participants selected initial grasp postures that ensured end-state comfort during non-perturbed trials. In addition, participants made appropriate on-line corrections to their reach-to-grasp movements to ensure end-state comfort during perturbed trials. Corrections in grasp posture occurred early or late in the reach-to-grasp phase. The results indicate that individuals plan their movements to afford comfort at the end of the movement, and that grasp posture planning is controlled via both feedforward and feedback mechanisms. PMID:22970119

  7. In vivo definition of parieto-motor connections involved in planning of grasping movements.

    Science.gov (United States)

    Koch, Giacomo; Cercignani, Mara; Pecchioli, Cristiano; Versace, Viviana; Oliveri, Massimiliano; Caltagirone, Carlo; Rothwell, John; Bozzali, Marco

    2010-05-15

    We combined bifocal transcranial magnetic stimulation (TMS) and diffusion tensor imaging (DTI) tractography to investigate in humans the contribution of connections originating from different parietal areas in planning of different reaching to grasp movements. TMS experiments revealed that in the left hemisphere functional connectivity between the primary motor cortex (M1) and a portion of the angular gyrus (AG) close to the caudal intraparietal sulcus was activated during early preparation of reaching and grasping movements only when the movement was made with a whole hand grasp (WHG) towards objects in contralateral space. In contrast, a different pathway, linking M1 with a part of the supramarginal gyrus (SMG) close to the anterior intraparietal sulcus, was sensitive only to the type of grasp required (precision grasping) but not to the position of the object in space. A triple coil experiment revealed that inactivation of the ventral premotor area (PMv) by continuous theta burst stimulation interfered with some of these interactions. Anatomical DTI tractography revealed that AG and SMG are strongly connected with PMv and with M1 by different bundles of the superior longitudinal fasciculus (SLF). These results demonstrate the existence of segregated parieto-premotor-motor pathways crucial for preparation of different grasping actions and indicate that these may process information relevant to both the position of the object and the hand shape required to use it. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  8. Functional morphology of the hallucal metatarsal with implications for inferring grasping ability in extinct primates.

    Science.gov (United States)

    Goodenberger, Katherine E; Boyer, Doug M; Orr, Caley M; Jacobs, Rachel L; Femiani, John C; Patel, Biren A

    2015-03-01

    Primate evolutionary morphologists have argued that selection for life in a fine branch niche resulted in grasping specializations that are reflected in the hallucal metatarsal (Mt1) morphology of extant "prosimians", while a transition to use of relatively larger, horizontal substrates explains the apparent loss of such characters in anthropoids. Accordingly, these morphological characters-Mt1 torsion, peroneal process length and thickness, and physiological abduction angle-have been used to reconstruct grasping ability and locomotor mode in the earliest fossil primates. Although these characters are prominently featured in debates on the origin and subsequent radiation of Primates, questions remain about their functional significance. This study examines the relationship between these morphological characters of the Mt1 and a novel metric of pedal grasping ability for a large number of extant taxa in a phylogenetic framework. Results indicate greater Mt1 torsion in taxa that engage in hallucal grasping and in those that utilize relatively small substrates more frequently. This study provides evidence that Carpolestes simpsoni has a torsion value more similar to grasping primates than to any scandentian. The results also show that taxa that habitually grasp vertical substrates are distinguished from other taxa in having relatively longer peroneal processes. Furthermore, a longer peroneal process is also correlated with calcaneal elongation, a metric previously found to reflect leaping proclivity. A more refined understanding of the functional associations between Mt1 morphology and behavior in extant primates enhances the potential for using these morphological characters to comprehend primate (locomotor) evolution. © 2014 Wiley Periodicals, Inc.

  9. Psychomotor performance in relation to acute oral administration of Delta9-tetrahydrocannabinol and standardized cannabis extract in healthy human subjects.

    Science.gov (United States)

    Roser, Patrik; Gallinat, Jürgen; Weinberg, Gordon; Juckel, Georg; Gorynia, Inge; Stadelmann, Andreas M

    2009-08-01

    Abnormalities in psychomotor performance are a consistent finding in schizophrenic patients as well as in chronic cannabis users. The high levels of central cannabinoid (CB(1)) receptors in the basal ganglia, the cerebral cortex and the cerebellum indicate their implication in the regulation of motor activity. Based on the close relationship between cannabis use, the endogenous cannabinoid system and motor disturbances found in schizophrenia, we expected that administration of cannabinoids may change pattern of psychomotor activity like in schizophrenic patients. This prospective, double-blind, placebo-controlled cross-over study investigated the acute effects of cannabinoids on psychomotor performance in 24 healthy right-handed volunteers (age 27.9 +/- 2.9 years, 12 male) by comparing Delta(9)-tetrahydrocannabinol (Delta(9)-THC) and standardized cannabis extract containing Delta(9)-THC and cannabidiol. Psychomotor performance was assessed by using a finger tapping test series. Cannabis extract, but not Delta(9)-THC, revealed a significant reduction of right-hand tapping frequencies that was also found in schizophrenia. As to the pure Delta(9)-THC condition, left-hand tapping frequencies were correlated with the plasma concentrations of the Delta(9)-THC metabolite 11-OH-THC. These effects are thought to be related to cannabinoid actions on CB(1) receptors in the basal ganglia, the cerebral cortex and the cerebellum. Our data further demonstrate that acute CB(1) receptor activation under the cannabis extract condition may also affect intermanual coordination (IMC) as an index of interhemispheric transfer. AIR-Scale scores as a measure of subjective perception of intoxication were dose-dependently related to IMC which was shown by an inverted U-curve. This result may be due to functional changes involving GABAergic and glutamatergic neurotransmission within the corpus callosum.

  10. G3DB: A database of successful and failed grasps with RGB-D images, point clouds, mesh models and gripper parameters

    CSIR Research Space (South Africa)

    Kleinhans, A

    2015-05-01

    Full Text Available is with the University of Lie`ge, Belgium renaud.detry@ulg.ac.be direct mapping from vision to grasp parameters. A learning- based grasp planner does not necessitate the operator to input hundreds of rules defining how to plan a grasp based on the shape of an object...; it instead extracts those rules automatically from grasp examples. A common requirement of grasp learning algorithms is thus a database of grasp examples, representative of a variety of objects and relative hand-object configurations. A database of grasp...

  11. Bodily Expression Support for Creative Dance Education by Grasping-Type Musical Interface with Embedded Motion and Grasp Sensors

    Directory of Open Access Journals (Sweden)

    Tomoyuki Yamaguchi

    2017-05-01

    Full Text Available Dance has been made mandatory as one of the physical education courses in Japan because it can cultivate capacities for expression and communication. Among several types of dance education, creative dance especially contributes to the cultivation of these capacities. However, creative dance requires some level of particular skills, as well as creativity, and it is difficult to presuppose these pre-requisites in beginner-level dancers without experience. We propose a novel supporting device for dance beginners to encourage creative dance performance by continuously generating musical sounds in real-time in accordance with their bodily movements. It has embedded sensors developed for this purpose. Experiments to evaluate the effectiveness of the device were conducted with ten beginner-level dancers. Using the proposed device, the subjects demonstrated enhanced creative dance movements with greater variety, evaluated in terms of Laban dance movement description. Also, using the device, they performed with better accuracy and repeatability in a task where they produced an imagined circular trajectory by hand. The proposed interface is effective in terms of creative dance activity and accuracy of motion generation for beginner-level dancers.

  12. Bodily Expression Support for Creative Dance Education by Grasping-Type Musical Interface with Embedded Motion and Grasp Sensors †

    Science.gov (United States)

    Yamaguchi, Tomoyuki; Kadone, Hideki

    2017-01-01

    Dance has been made mandatory as one of the physical education courses in Japan because it can cultivate capacities for expression and communication. Among several types of dance education, creative dance especially contributes to the cultivation of these capacities. However, creative dance requires some level of particular skills, as well as creativity, and it is difficult to presuppose these pre-requisites in beginner-level dancers without experience. We propose a novel supporting device for dance beginners to encourage creative dance performance by continuously generating musical sounds in real-time in accordance with their bodily movements. It has embedded sensors developed for this purpose. Experiments to evaluate the effectiveness of the device were conducted with ten beginner-level dancers. Using the proposed device, the subjects demonstrated enhanced creative dance movements with greater variety, evaluated in terms of Laban dance movement description. Also, using the device, they performed with better accuracy and repeatability in a task where they produced an imagined circular trajectory by hand. The proposed interface is effective in terms of creative dance activity and accuracy of motion generation for beginner-level dancers. PMID:28531114

  13. Bodily Expression Support for Creative Dance Education by Grasping-Type Musical Interface with Embedded Motion and Grasp Sensors.

    Science.gov (United States)

    Yamaguchi, Tomoyuki; Kadone, Hideki

    2017-05-20

    Dance has been made mandatory as one of the physical education courses in Japan because it can cultivate capacities for expression and communication. Among several types of dance education, creative dance especially contributes to the cultivation of these capacities. However, creative dance requires some level of particular skills, as well as creativity, and it is difficult to presuppose these pre-requisites in beginner-level dancers without experience. We propose a novel supporting device for dance beginners to encourage creative dance performance by continuously generating musical sounds in real-time in accordance with their bodily movements. It has embedded sensors developed for this purpose. Experiments to evaluate the effectiveness of the device were conducted with ten beginner-level dancers. Using the proposed device, the subjects demonstrated enhanced creative dance movements with greater variety, evaluated in terms of Laban dance movement description. Also, using the device, they performed with better accuracy and repeatability in a task where they produced an imagined circular trajectory by hand. The proposed interface is effective in terms of creative dance activity and accuracy of motion generation for beginner-level dancers.

  14. The responses of subjective feeling, task performance ability, cortisol and HRV for the various types of floor impact sound: a pilot study

    National Research Council Canada - National Science Library

    Seok Hyeon Yun; Sang Jin Park; Chang Sun Sim; Joo Hyun Sung; Ahra Kim; Jang Myeong Lee; Sang Hyun Lee; Jiho Lee

    2017-01-01

    ...) may have the different effects on the human’s body and mind. The purpose of this study is to assess the responses of subjective feeling, task performance ability, cortisol and HRV for the various types of floor impact...

  15. Underground verification of the large deflection performance of fibre reinforced shotcrete subjected to high stresses and convergence and to dynamic loading.

    CSIR Research Space (South Africa)

    Joughin, WC

    2002-04-01

    Full Text Available Committee Final Project Report Underground verification of the large deflection performance of fibre reinforced shotcrete subjected to high stresses and convergence and to dynamic loading W.C. Joughin, J.L. Human and P.J. Terbrugge Research agency...: Steffen, Robertson and Kirsten Project number: GAP 710 Date: April 2002 2 Executive summary The underground verification of the performance of fibre reinforced shotcrete, subject to high stresses, convergence and dynamic loading, was identified...

  16. Tribological performance evaluation of coated steels with TiNbCN subjected to tribo-chemical wear in Ringers solution

    Energy Technology Data Exchange (ETDEWEB)

    Caballero G, J.; Aperador, W. [Universidad Militar Nueva Granada, Volta Research Group, 101-80 Bogota (Colombia); Caicedo, J. C., E-mail: g.ing.materiales@gmail.com [Universidad del Valle, Tribology Polymers, Powder Metallurgy and Processing of Solid Recycled Research Group, Cali (Colombia)

    2016-11-01

    With the aim of generating solutions against the deterioration of the joint prostheses, it was studied the tribo-corrosive behavior of titanium niobium carbonitride (TiNbCN) deposited on stainless steel AISI 316 LVM using the technique of magnetron sputtering physical vapor deposition. The tests were performed in a balanced saline solution (Ringers solution) which represents the characteristics of the body fluids, using an equipment where the micro-abrasive wear is generated by the contact of micro particles in the system; the micro-abrasion-corrosion mechanism is described by means of the incorporation of an electrochemical cell consisting of three electrodes. Both the substrate and the coating, were subjected to micro-abrasive wear simultaneously with the electrochemical tests of Tafel polarization curves and electrochemical impedance spectroscopy (EIS); subsequently of the tests, the specimens were analyzed by optical microscopy and scanning electron microscopy characterizing the surface morphology. It was observed that the coating presents an increase in its corrosion and wear resistance with the presence of a simulated biological fluid. The samples were characterized via X-ray diffraction. (Author)

  17. Performance of Patient-Generated Subjective Global Assessment (PG-SGA) in Patients With Advanced Cancer in Palliative Care.

    Science.gov (United States)

    Wiegert, Emanuelly Varea Maria; Padilha, Patricia de Carvalho; Peres, Wilza Arantes Ferreira

    2017-10-01

    The purpose of this study was to evaluate the prognostic significance of the Patient-Generated Subjective Global Assessment (PG-SGA) in patients receiving palliative care for advanced cancer. The PG-SGA was used to assess nutrition status of 120 patients admitted to the Palliative Care Unit at the National Cancer Institute in Brazil. According to the PG-SGA, 94.2% (n = 113) of the patients were evaluated as malnourished. The PG-SGA evaluated that xerostomia was the only symptom associated with a short survival (odds ratio [OR], 2.54; 95% confidence interval [CI], 1.2-5.38; P = .014). Survival was found to be significantly higher in well-nourished (PG-SGA A) than malnourished (PG-SGA B [ P = .021] or C [ P = .013]) patients. Total PG-SGA score (hazard ratio [HR], 1.06; 95% CI, 1.001-1.09; P = .045) and Karnofsky Performance Status of 20%-30% (HR, 15.4; 95% CI, 1.63-92.9; P = .001) and 40%-50% (HR, 10.0; 95% CI, 1.22-64.9; P = .031) were found to be independent prognostic survival factors. The scored PG-SGA is an independent prognostic factor of survival and thus can be a useful tool for nutrition evaluation in palliative care.

  18. Closed-Loop Neuroprosthesis for Reach-to-Grasp Assistance: Combining Adaptive Multi-channel Neuromuscular Stimulation with a Multi-joint Arm Exoskeleton

    Science.gov (United States)

    Grimm, Florian; Gharabaghi, Alireza

    2016-01-01

    Stroke patients with severe motor deficits cannot execute task-oriented rehabilitation exercises with their affected upper extremity. Advanced rehabilitation technology may support them in performing such reach-to-grasp movements. The challenge is, however, to provide assistance as needed, while maintaining the participants' commitment during the exercises. In this feasibility study, we introduced a closed-loop neuroprosthesis for reach-to-grasp assistance which combines adaptive multi-channel neuromuscular stimulation with a multi-joint arm exoskeleton. Eighteen severely affected chronic stroke patients were assisted by a gravity-compensating, seven-degree-of-freedom exoskeleton which was attached to the paretic arm for performing reach-to-grasp exercises resembling activities of daily living in a virtual environment. During the exercises, adaptive electrical stimulation was applied to seven different muscles of the upper extremity in a performance-dependent way to enhance the task-oriented movement trajectory. The stimulation intensity was individualized for each targeted muscle and remained subthreshold, i.e., induced no overt support. Closed-loop neuromuscular stimulation could be well integrated into the exoskeleton-based training, and increased the task-related range of motion (p = 0.0004) and movement velocity (p = 0.015), while preserving accuracy. The highest relative stimulation intensity was required to facilitate the grasping function. The facilitated range of motion correlated with the upper extremity Fugl-Meyer Assessment score of the patients (p = 0.028). Combining adaptive multi-channel neuromuscular stimulation with antigravity assistance amplifies the residual motor capabilities of severely affected stroke patients during rehabilitation exercises and may thus provide a customized training environment for patient-tailored support while preserving the participants' engagement. PMID:27445658

  19. Closed-Loop Neuroprosthesis for Reach-to-Grasp Assistance: Combining Adaptive Multi-channel Neuromuscular Stimulation with a Multi-joint Arm Exoskeleton.

    Science.gov (United States)

    Grimm, Florian; Gharabaghi, Alireza

    2016-01-01

    Stroke patients with severe motor deficits cannot execute task-oriented rehabilitation exercises with their affected upper extremity. Advanced rehabilitation technology may support them in performing such reach-to-grasp movements. The challenge is, however, to provide assistance as needed, while maintaining the participants' commitment during the exercises. In this feasibility study, we introduced a closed-loop neuroprosthesis for reach-to-grasp assistance which combines adaptive multi-channel neuromuscular stimulation with a multi-joint arm exoskeleton. Eighteen severely affected chronic stroke patients were assisted by a gravity-compensating, seven-degree-of-freedom exoskeleton which was attached to the paretic arm for performing reach-to-grasp exercises resembling activities of daily living in a virtual environment. During the exercises, adaptive electrical stimulation was applied to seven different muscles of the upper extremity in a performance-dependent way to enhance the task-oriented movement trajectory. The stimulation intensity was individualized for each targeted muscle and remained subthreshold, i.e., induced no overt support. Closed-loop neuromuscular stimulation could be well integrated into the exoskeleton-based training, and increased the task-related range of motion (p = 0.0004) and movement velocity (p = 0.015), while preserving accuracy. The highest relative stimulation intensity was required to facilitate the grasping function. The facilitated range of motion correlated with the upper extremity Fugl-Meyer Assessment score of the patients (p = 0.028). Combining adaptive multi-channel neuromuscular stimulation with antigravity assistance amplifies the residual motor capabilities of severely affected stroke patients during rehabilitation exercises and may thus provide a customized training environment for patient-tailored support while preserving the participants' engagement.

  20. Concatenation of observed grasp phases with observer's distal movements: a behavioural and TMS study.

    Directory of Open Access Journals (Sweden)

    Elisa De Stefani

    Full Text Available The present study aimed at determining how actions executed by two conspecifics can be coordinated with each other, or more specifically, how the observation of different phases of a reaching-grasping action is temporary related to the execution of a movement of the observer. Participants observed postures of initial finger opening, maximal finger aperture, and final finger closing of grasp after observation of an initial hand posture. Then, they opened or closed their right thumb and index finger (experiments 1, 2 and 3. Response times decreased, whereas acceleration and velocity of actual finger movements increased when observing the two late phases of grasp. In addition, the results ruled out the possibility that this effect was due to salience of the visual stimulus when the hand was close to the target and confirmed an effect of even hand postures in addition to hand apparent motion due to the succession of initial hand posture and grasp phase. In experiments 4 and 5, the observation of grasp phases modulated even foot movements and pronunciation of syllables. Finally, in experiment 6, transcranial magnetic stimulation applied to primary motor cortex 300 ms post-stimulus induced an increase in hand motor evoked potentials of opponens pollicis muscle when observing the two late phases of grasp. These data suggest that the observation of grasp phases induced simulation which was stronger during observation of finger closing. This produced shorter response times, greater acceleration and velocity of the successive movement. In general, our data suggest best concatenation between two movements (one observed and the other executed when the observed (and simulated movement was to be accomplished. The mechanism joining the observation of a conspecific's action with our own movement may be precursor of social functions. It may be at the basis for interactions between conspecifics, and related to communication between individuals.

  1. Emergent Coordination Underlying Learning to Reach-to-Grasp with a Brain-Machine Interface.

    Science.gov (United States)

    Vaidya, Mukta; Balasubramanian, Karthikeyan; Southerland, Joshua; Badreldin, Islam; Eleryan, Ahmed; Shattuck, Kelsey; Gururangan, Suchin; Slutzky, Marc W; Osborne, Leslie C; Fagg, Andrew H; Oweiss, Karim G; Hatsopoulos, Nicholas G

    2017-12-13

    The development of coordinated reach to grasp has been well-studied in infants and children (Kuhtz-Buschbeck, Stolze, Jöhnk, Boczek-Funcke, & Illert, 1998; von Hofsten, 1984a). However, the role of motor cortex during this development is unclear because it is difficult to study in humans. We took the approach using a brain-machine interface (BMI) paradigm in rhesus macaques with prior therapeutic amputations to examine the emergence of novel, coordinated reach-to-grasp. Previous research has shown that after amputation, the cortical area previously involved in the control of the lost limb undergoes reorganization (Qi, Stepniewska, & Kaas, 2000; Schieber & Deuel, 1997; Wu & Kaas, 1999), but prior BMI work has largely relied on finding neurons that already encode specific movement-related information. Here, we taught macaques to cortically control a robotic arm and hand through operant conditioning using neurons that were not explicitly reach- or grasp-related. Over the course of training, stereotypical patterns emerged and stabilized in the cross-covariance between the reaching and grasping velocity profiles, between pairs of neurons involved in controlling reach and grasp, and to a comparable, but lesser, extent between other stable neurons in the network. In fact, we found evidence of this structured coordination between pairs composed of all combinations of neurons decoding reach or grasp, and other stable neurons in the network. The degree of and participation in coordination was highly correlated across all pair-types. Our approach provides a unique model for studying the development of novel, coordinated reach-to-grasp at the behavioral and cortical levels.

  2. Local field potentials in primate motor cortex encode grasp kinetic parameters.

    Science.gov (United States)

    Milekovic, Tomislav; Truccolo, Wilson; Grün, Sonja; Riehle, Alexa; Brochier, Thomas

    2015-07-01

    Reach and grasp kinematics are known to be encoded in the spiking activity of neuronal ensembles and in local field potentials (LFPs) recorded from primate motor cortex during movement planning and execution. However, little is known, especially in LFPs, about the encoding of kinetic parameters, such as forces exerted on the object during the same actions. We implanted two monkeys with microelectrode arrays in the motor cortical areas MI and PMd to investigate encoding of grasp-related parameters in motor cortical LFPs during planning and execution of reach-and-grasp movements. We identified three components of the LFP that modulated during grasps corresponding to low (0.3-7Hz), intermediate (~10-~40Hz) and high (~80-250Hz) frequency bands. We show that all three components can be used to classify not only grip types but also object loads during planning and execution of a grasping movement. In addition, we demonstrate that all three components recorded during planning or execution can be used to continuously decode finger pressure forces and hand position related to the grasping movement. Low and high frequency components provide similar classification and decoding accuracies, which were substantially higher than those obtained from the intermediate frequency component. Our results demonstrate that intended reach and grasp kinetic parameters are encoded in multiple LFP bands during both movement planning and execution. These findings also suggest that the LFP is a reliable signal for the control of parameters related to object load and applied pressure forces in brain-machine interfaces. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. When perception trips action! The increase in the perceived size of both hand and target matters in reaching and grasping movements.

    Science.gov (United States)

    Ambron, Elisabetta; Schettino, Luis F; Coyle, Marlee; Jax, Steven; Coslett, H Branch

    2017-10-01

    Reaching and grasping movements rely on visual information regarding the target characteristics (e.g. size) and the hand position during the action execution. Changes in the visual representation of the body (e.g. increase in the perceived size of the hand) can modify action performance, but it is still unclear how these modifications interact with changes in the external environment. We investigated this topic by manipulating the perceived size of both hand and target objects and the degree of visual feedback available during the movement execution. Ten young adults were asked to reach and grasp geometrical objects in four different conditions: (i) with normal vision with the light on, (ii) with normal vision in the dark, (iii) using magnifying lenses in the light and (iv) using magnifying lenses in the dark. In contrast with previous works, our results show that movement execution is longer in magnified vision compared to normal when the action is executed in the light, but the grasping component was not affected by changes in size in this condition. On the contrary, when the visual feedback of the hand was removed and participants performed the action in the dark, movements were faster and the distances across fingers larger in the magnified than normal vision. This pattern of data suggests that grasping movements adapt rapidly and compensate for changes in vision when this process depends on the degree of visual feedback and/or environmental cues available. In the debate regarding the dissociation between action and perception, our data suggest that action may overcome changes in perception when visual feedback is available, but perception may trick action in situations of reduced visual information. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Testing of Performance of Optical Fibers Under Irradiation in Intense Radiation Fields, When Subjected to Very High Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Blue, Thomas [The Ohio State Univ., Columbus, OH (United States); Windl, Wolfgang [The Ohio State Univ., Columbus, OH (United States); Dickerson, Bryan [Luna Innovations, Inc. (United States)

    2013-01-03

    The primary objective of this project is to measure and model the performance of optical fibers in intense radiation fields when subjected to very high temperatures. This research will pave the way for fiber optic and optically based sensors under conditions expected in future high-temperature gas-cooled reactors. Sensor life and signal-to-noise ratios are susceptible to attenuation of the light signal due to scattering and absorbance in the fibers. This project will provide an experimental and theoretical study of the darkening of optical fibers in high-radiation and high-temperature environments. Although optical fibers have been studied for moderate radiation fluence and flux levels, the results of irradiation at very high temperatures have not been published for extended in-core exposures. Several previous multi-scale modeling efforts have studied irradiation effects on the mechanical properties of materials. However, model-based prediction of irradiation-induced changes in silica's optical transport properties has only recently started to receive attention due to possible applications as optical transmission components in fusion reactors. Nearly all damage-modeling studies have been performed in the molecular-dynamics domain, limited to very short times and small systems. Extended-time modeling, however, is crucial to predicting the long-term effects of irradiation at high temperatures, since the experimental testing may not encompass the displacement rate that the fibers will encounter if they are deployed in the VHTR. The project team will pursue such extended-time modeling, including the effects of the ambient and recrystallization. The process will be based on kinetic MC modeling using the concept of amorphous material consisting of building blocks of defect-pairs or clusters, which has been successfully applied to kinetic modeling in amorphized and recrystallized silicon. Using this procedure, the team will model compensation for rate effects, and

  5. Effects of repeated snowboard exercise in virtual reality with time lags of visual scene behind body rotation on head stability and subjective slalom run performance in healthy young subjects.

    Science.gov (United States)

    Wada, Yoshiro; Nishiike, Suetaka; Kitahara, Tadashi; Yamanaka, Toshiaki; Imai, Takao; Ito, Taeko; Sato, Go; Matsuda, Kazunori; Kitamura, Yoshiaki; Takeda, Noriaki

    2016-11-01

    After repeated snowboard exercises in the virtual reality (VR) world with increasing time lags in trials 3-8, it is suggested that the adaptation to repeated visual-vestibulosomatosensory conflict in the VR world improved dynamic posture control and motor performance in the real world without the development of motion sickness. The VR technology was used and the effects of repeated snowboard exercise examined in the VR world with time lags between visual scene and body rotation on the head stability and slalom run performance during exercise in healthy subjects. Forty-two healthy young subjects participated in the study. After trials 1 and 2 of snowboard exercise in the VR world without time lag, trials 3-8 were conducted with 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6 s time lags of the visual scene that the computer creates behind board rotation, respectively. Finally, trial 9 was conducted without time lag. Head linear accelerations and subjective slalom run performance were evaluated. The standard deviations of head linear accelerations in inter-aural direction were significantly increased in trial 8, with a time lag of 0.6 s, but significantly decreased in trial 9 without a time lag, compared with those in trial 2 without a time lag. The subjective scores of slalom run performance were significantly decreased in trial 8, with a time lag of 0.6 s, but significantly increased in trial 9 without a time lag, compared with those in trial 2 without a time lag. Motion sickness was not induced in any subjects.

  6. Grasping two-dimensional images and three-dimensional objects in visual-form agnosia.

    Science.gov (United States)

    Westwood, David A; Danckert, James; Servos, Philip; Goodale, Melvyn A

    2002-05-01

    Visually guided prehension is controlled by a specialized visuomotor system in the posterior parietal cortex. It is not clear how this system responds to visual stimuli that lack three-dimensional (3D) structure, such as two-dimensional (2D) images of objects. We asked a neurological patient with visual-form agnosia (patient D.F.) to grasp 3D objects and 2D images of the same objects and to estimate their sizes manually. D.F.'s grip aperture was scaled to the sizes of the 2D and 3D target stimuli, but her manual estimates were poorly correlated with object size. Control participants demonstrated appropriate size-scaling in both the grasping and manual size-estimation tasks, but tended to use a smaller peak aperture when reaching to grasp 2D images. We conclude that: (1) the dorsal stream grasping system does not discriminate in a fundamental way between 2D and 3D objects, and (2) neurologically normal participants might adopt a different visuomotor strategy for target objects that are recognized to be ungraspable. These findings are consistent with the view that the dorsal grasping system accesses a pragmatic, spatial representation of the target object, whereas the ventral system accesses a more comprehensive, volumetric description of the object.

  7. Viewing geometry determines the contribution of binocular vision to the online control of grasping.

    Science.gov (United States)

    Keefe, Bruce D; Watt, Simon J

    2017-12-01

    Binocular vision is often assumed to make a specific, critical contribution to online visual control of grasping by providing precise information about the separation between digits and object. This account overlooks the 'viewing geometry' typically encountered in grasping, however. Separation of hand and object is rarely aligned precisely with the line of sight (the visual depth dimension), and analysis of the raw signals suggests that, for most other viewing angles, binocular feedback is less precise than monocular feedback. Thus, online grasp control relying selectively on binocular feedback would not be robust to natural changes in viewing geometry. Alternatively, sensory integration theory suggests that different signals contribute according to their relative precision, in which case the role of binocular feedback should depend on viewing geometry, rather than being 'hard-wired'. We manipulated viewing geometry, and assessed the role of binocular feedback by measuring the effects on grasping of occluding one eye at movement onset. Loss of binocular feedback resulted in a significantly less extended final slow-movement phase when hand and object were separated primarily in the frontoparallel plane (where binocular information is relatively imprecise), compared to when they were separated primarily along the line of sight (where binocular information is relatively precise). Consistent with sensory integration theory, this suggests the role of binocular (and monocular) vision in online grasp control is not a fixed, 'architectural' property of the visuo-motor system, but arises instead from the interaction of viewer and situation, allowing robust online control across natural variations in viewing geometry.

  8. Improvement of grasping after motor imagery in C6-C7 tetraplegia: A kinematic and MEG pilot study.

    Science.gov (United States)

    Mateo, Sébastien; Di Rienzo, Franck; Reilly, Karen T; Revol, Patrice; Delpuech, Claude; Daligault, Sébastien; Guillot, Aymeric; Jacquin-Courtois, Sophie; Luauté, Jacques; Rossetti, Yves; Collet, Christian; Rode, Gilles

    2015-01-01

    Grasp recovery after C6-C7-spinal cord injury (SCI) requires learning "tenodesis grasp" whereby active wrist extension elicits passive thumb-to-forefinger and finger-to-palm flexion. Evidence that motor imagery (MI) promotes upper limb function after tetraplegia is growing, but whether MI potentiates grasp recovery in C6-C7-SCI individuals who have successfully learned the "tenodesis grasp" remains unknown. Six chronic stable C6-C7-SCI inpatients and six healthy control participants were included. C6-C7-SCI participants imagined grasping movements and controls visualized geometric forms for 45 minutes, three times a week for five weeks. Three separate measures taken over a five week period before the intervention formed the baseline. Intervention effects were assessed immediately after the intervention and eight weeks later. Each testing session consisted of kinematic recordings during reach-to-grasp and magnetoencephalographic (MEG) recordings during wrist extension. During baseline, kinematic wrist extension angle during "tenodesis grasp" and MEG contralateral sensorimotor cortex (cSMC) activity during wrist extension were stable. Moreover, SCI participants exhibited a greater number of voxels within cSMC than controls. After MI sessions, wrist extension angle increased during "tenodesis grasp" and the number of voxels within cSMC during wrist extension decreased and became similar to controls. These findings provide further support for the use of MI to reinforce a compensatory grasping movement (tenodesis) and induce brain plasticity.

  9. Compensation or Restoration: Closed-Loop Feedback of Movement Quality for Assisted Reach-to-Grasp Exercises with a Multi-Joint Arm Exoskeleton.

    Science.gov (United States)

    Grimm, Florian; Naros, Georgios; Gharabaghi, Alireza

    2016-01-01

    Assistive technology allows for intensive practice and kinematic measurements during rehabilitation exercises. More recent approaches attach a gravity-compensating multi-joint exoskeleton to the upper extremity to facilitate task-oriented training in three-dimensional space with virtual reality feedback. The movement quality, however, is mostly captured through end-point measures that lack information on proximal inter-joint coordination. This limits the differentiation between compensation strategies and genuine restoration both during the exercise and in the course of rehabilitation. We extended in this proof-of-concept study a commercially available seven degree-of-freedom arm exoskeleton by using the real-time sensor data to display a three-dimensional multi-joint visualization of the user's arm. Ten healthy subjects and three severely affected chronic stroke patients performed reach-to-grasp exercises resembling activities of daily living assisted by the attached exoskeleton and received closed-loop online feedback of the three-dimensional movement in virtual reality. Patients in this pilot study differed significantly with regard to motor performance (accuracy, temporal efficiency, range of motion) and movement quality (proximal inter-joint coordination) from the healthy control group. In the course of 20 training and feedback sessions over 4 weeks, these pathological measures improved significantly toward the reference parameters of healthy participants. It was moreover feasible to capture the evolution of movement pattern kinematics of the shoulder and elbow and to quantify the individual degree of natural movement restoration for each patient. The virtual reality visualization and closed-loop feedback of joint-specific movement kinematics makes it possible to detect compensation strategies and may provide a tool to achieve the rehabilitation goals in accordance with the individual capacity for genuine functional restoration; a proposal that warrants

  10. A Dynamic Programming Based Improvement Heuristic for a Repetitive Routing Problem of Grasp-and-Delivery Robots

    Science.gov (United States)

    Shurbevski, Aleksandar; Karuno, Yoshiyuki; Nagamochi, Hiroshi

    We consider a repetitive routing problem of a single grasp-and-delivery robot used on a printed circuit board (PCB) assembly line. The robot arranges n identical pins from their current configuration to the next required one by transferring at most one pin at a time. The pins support a PCB from underneath to prevent it from overbending, while an automated manipulator embeds electronic parts in the PCB from above. Given an initial configuration of pins and a sequence of m required configurations, the problem asks to find a transfer route of the robot that minimizes the route length over all m transitions. A polynomial time approximation algorithm with factor two has been proposed by the authors to the problem. In this paper, we design a dynamic programming (DP) procedure to improve its empirical performance, and also conduct numerical experiments to show how well the proposed DP procedure performs.

  11. Increased motor cortex excitability during motor imagery in brain-computer interface trained subjects

    Directory of Open Access Journals (Sweden)

    Olesya eMokienko

    2013-11-01

    Full Text Available Background: Motor imagery (MI is the mental performance of movement without muscle activity. It is generally accepted that MI and motor performance have similar physiological mechanisms.Purpose: To investigate the activity and excitability of cortical motor areas during MI in subjects who were previously trained with an MI-based brain-computer interface (BCI.Subjects and methods: Eleven healthy volunteers without neurological impairments (mean age, 36 years; range: 24–68 years were either trained with an MI-based BCI (BCI-trained, n = 5 or received no BCI training (n = 6, controls. Subjects imagined grasping in a blocked paradigm task with alternating rest and task periods. For evaluating the activity and excitability of cortical motor areas we used functional MRI and navigated transcranial magnetic stimulation (nTMS.Results: fMRI revealed activation in Brodmann areas 3 and 6, the cerebellum, and the thalamus during MI in all subjects. The primary motor cortex was activated only in BCI-trained subjects. The associative zones of activation were larger in non-trained subjects. During MI, motor evoked potentials recorded from two of the three targeted muscles were significantly higher only in BCI-trained subjects. The motor threshold decreased (median = 17% during MI, which was also observed only in BCI-trained subjects.Conclusion: Previous BCI training increased motor cortex excitability during MI. These data may help to improve BCI applications, including rehabilitation of patients with cerebral palsy.

  12. Performance Evaluation of Waterproofing Membrane Systems Subject to the Concrete Joint Load Behavior of Below-Grade Concrete Structures

    National Research Council Canada - National Science Library

    Jaeyoung Song; Kyuhwan Oh; Byoungil Kim; Sangkeun Oh

    2017-01-01

    .... In this type of environment, they become subject to higher water pressure. The concrete material of the structures is exposed to wet conditions for longer periods of time, which makes the proper adhesion of waterproofing membranes difficult...

  13. A modular force-controlled robotic instrument for minimally invasive surgery - efficacy for being used in autonomous grasping against a variable pull force.

    Science.gov (United States)

    Khadem, Seyed Mohsen; Behzadipour, Saeed; Mirbagheri, Alireza; Farahmand, Farzam

    2016-12-01

    Many deficiencies of minimally invasive robotic surgery systems can be eliminated by using automated laparoscopic tools with force measurement and control capability. A fully modular, automated laparoscopic instrument with a proximal force sensory system was designed and fabricated. The efficacy of the instrument was evaluated experimentally when functioning in an autonomous force-controlled grasping scheme. The designed instrument was shown to work easily with standard laparoscopic tools, with the whole distal part detachable for autoclave sterilization. The root mean squared error (RMSE) of the actual pinch force from the target ramp was 0.318 N; it was 0.402 N for a sinusoidal pull force, which dropped by 21% using a static friction compensation. A secure grasping condition was achieved, in spite of this error, by applying a sufficiently large margin from the slip boundary. With a simple and practical design, the instrument enjoys affordability, versatility and autoclave sterilizability for clinical usage, with an acceptable performance for being used in an auto-grasping control scheme. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  14. Statistical Identification of Composed Visual Features Indicating High Likelihood of Grasp Success

    DEFF Research Database (Denmark)

    Thomsen, Mikkel Tang; Bodenhagen, Leon; Krüger, Norbert

    2013-01-01

    configurations of three 3D surface features that predict grasping actions with a high success probability. The strategy is based on first computing spatial relations between visual entities and secondly, exploring the cross-space of these relational feature space and grasping actions. The data foundation...... on a set of novel objects and evaluating the proposed grasping actions in dynamic simulation. In this validation, we have achieved an average success-rate between 0.74 and 0.89 when relying on the information inherent in configuration of three 3D surface features.......In this paper, we address the problem of extracting knowledge on the graspability of unknown objects based on visual information using an Early Cognitive Vision system representing contours and surfaces on different level of granularity. We present an approach towards automatically identifying...

  15. A General Contact Fo