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Sample records for visuomotor adaptive improvement

  1. Playing Action Video Games Improves Visuomotor Control.

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    Li, Li; Chen, Rongrong; Chen, Jing

    2016-08-01

    Can playing action video games improve visuomotor control? If so, can these games be used in training people to perform daily visuomotor-control tasks, such as driving? We found that action gamers have better lane-keeping and visuomotor-control skills than do non-action gamers. We then trained non-action gamers with action or nonaction video games. After they played a driving or first-person-shooter video game for 5 or 10 hr, their visuomotor control improved significantly. In contrast, non-action gamers showed no such improvement after they played a nonaction video game. Our model-driven analysis revealed that although different action video games have different effects on the sensorimotor system underlying visuomotor control, action gaming in general improves the responsiveness of the sensorimotor system to input error signals. The findings support a causal link between action gaming (for as little as 5 hr) and enhancement in visuomotor control, and suggest that action video games can be beneficial training tools for driving. © The Author(s) 2016.

  2. Impact of Parkinson's Disease and Dopaminergic Medication on Adaptation to Explicit and Implicit Visuomotor Perturbations

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    Mongeon, David; Blanchet, Pierre; Messier, Julie

    2013-01-01

    The capacity to learn new visuomotor associations is fundamental to adaptive motor behavior. Evidence suggests visuomotor learning deficits in Parkinson's disease (PD). However, the exact nature of these deficits and the ability of dopamine medication to improve them are under-explored. Previous studies suggested that learning driven by large and…

  3. Robustness of muscle synergies during visuomotor adaptation

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    Reinhard eGentner

    2013-09-01

    Full Text Available During visuomotor adaptation a novel mapping between visual targets and motor commands is gradually acquired. How muscle activation patterns are affected by this process is an open question. We tested whether the structure of muscle synergies is preserved during adaptation to a visuomotor rotation. Eight subjects applied targeted isometric forces on a handle instrumented with a force transducer while electromyographic (EMG activity was recorded from 13 shoulder and elbow muscles. The recorded forces were mapped into horizontal displacements of a virtual sphere with simulated mass, elasticity, and damping. The task consisted of moving the sphere to a target at one of eight equally spaced directions. Subjects performed three baseline blocks of 32 trials, followed by six blocks with a 45° CW rotation applied to the planar force, and finally three wash-out blocks without the perturbation. The sphere position at 100 ms after movement onset revealed significant directional error at the beginning of the rotation, a gradual learning in subsequent blocks, and aftereffects at the beginning of the wash-out. The change in initial force direction was closely related to the change in directional tuning of the initial EMG activity of most muscles. Throughout the experiment muscle synergies extracted using a non-negative matrix factorization algorithm from the muscle patterns recorded during the baseline blocks could reconstruct the muscle patterns of all other blocks with an accuracy significantly higher than chance indicating structural robustness. In addition, the synergies extracted from individual blocks remained similar to the baseline synergies throughout the experiment. Thus synergy structure is robust during visuomotor adaptation suggesting that changes in muscle patterns are obtained by rotating the directional tuning of the synergy recruitment.

  4. In Experts, underlying processes that drive visuomotor adaptation are different than in Novices.

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    Leukel, Christian; Gollhofer, Albert; Taube, Wolfgang

    2015-01-01

    Processes responsible for improvements in motor performance are often contrasted in an explicit and an implicit part. Explicit learning enables task success by using strategic (declarative) knowledge. Implicit learning refers to a change in motor performance without conscious effort. In this study, we tested the contribution of explicit and implicit processes in a visuomotor adaptation task in subjects with different expertise in the task they were asked to adapt. Thirty handball players (Experts) and 30 subjects without handball experience (Novices) participated. Three experiments tested visuomotor adaptation of a free throw in team handball using prismatic glasses. The difference between experiments was that in Experiment 2 and 3, contribution of explicit processes was prevented, whereas Experiment 1 allowed contribution of explicit and implicit processes. Retention was assessed in Experiment 3. There were three main findings: (i) contribution of explicit processes to adaptation was stronger in Experts than Novices (Experiment 1); (ii) adaptation took longer in Experts when preventing contribution of explicit processes (Experiment 2); and (iii) retention was stronger in Experts (Experiment 3). This study shows that learning processes involved in visuomotor adaptation change by expertise, with more involvement of explicit processes and most likely other implicit processes to adaptation in Experts.

  5. Consolidation of visuomotor adaptation memory with consistent and noisy environments.

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    Maeda, Rodrigo S; McGee, Steven E; Marigold, Daniel S

    2017-01-01

    Our understanding of how we learn and retain motor behaviors is still limited. For instance, there is conflicting evidence as to whether the memory of a learned visuomotor perturbation consolidates; i.e., the motor memory becomes resistant to interference from learning a competing perturbation over time. Here, we sought to determine the factors that influence consolidation during visually guided walking. Subjects learned a novel mapping relationship, created by prism lenses, between the perceived location of two targets and the motor commands necessary to direct the feet to their positions. Subjects relearned this mapping 1 wk later. Different groups experienced protocols with or without a competing mapping (and with and without washout trials), presented either on the same day as initial learning or before relearning on day 2 We tested identical protocols under constant and noisy mapping structures. In the latter, we varied, on a trial-by-trial basis, the strength of prism lenses around a non-zero mean. We found that a novel visuomotor mapping is retained at least 1 wk after initial learning. We also found reduced foot-placement error with relearning in constant and noisy mapping groups, despite learning a competing mapping beforehand, and with the exception of one protocol, with and without washout trials. Exposure to noisy mappings led to similar performance on relearning compared with the equivalent constant mapping groups for most protocols. Overall, our results support the idea of motor memory consolidation during visually guided walking and suggest that constant and noisy practices are effective for motor learning. The adaptation of movement is essential for many daily activities. To interact with targets, this often requires learning the mapping to produce appropriate motor commands based on visual input. Here, we show that a novel visuomotor mapping is retained 1 wk after initial learning in a visually guided walking task. Furthermore, we find that this

  6. Age-related variations of visuo-motor adaptation beyond explicit knowledge

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    Herbert eHeuer

    2014-07-01

    Full Text Available Visuo-motor adaptation suffers at older working age. The age-related decline of behavioural adjustments is accompanied by reduced explicit knowledge of the visuo-motor transformation. It disappears when explicit knowledge is kept constant across the age range, except for particularly high levels of explicit knowledge. According to these findings, at older adult age both the acquisition of explicit knowledge and its application for strategic corrections become poorer. Recently it has been posited that visuo-motor adaptation can involve model-free reinforcement mechanisms of learning in addition to model-based mechanisms. We tested whether age-related declines of reinforcement learning can also contribute to the age-related changes of visuo-motor adaptation. Therefore we enhanced the contribution of reinforcement learning to visuo-motor adaptation by way of introducing salient markers of success and failure during practice. With such modified practice conditions, there were residual age-related variations of behavioural adjustments at all levels of explicit knowledge, even when explicit knowledge was absent. The residual age-related variations were observed for practiced target directions only, but not for new target directions. These findings are consistent with an age-related decline of model-free reinforcement learning as a third factor in the age-related decline of visuo-motor adaptation. Under practice conditions, which spur model-free reward-based learning, this factor adds to the decrements of the acquisition of explicit knowledge and its use for strategic corrections.

  7. Sleep benefits consolidation of visuo-motor adaptation learning in older adults.

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    Mantua, Janna; Baran, Bengi; Spencer, Rebecca M C

    2016-02-01

    Sleep is beneficial for performance across a range of memory tasks in young adults, but whether memories are similarly consolidated in older adults is less clear. Performance benefits have been observed following sleep in older adults for declarative learning tasks, but this benefit may be reduced for non-declarative, motor skill learning tasks. To date, studies of sleep-dependent consolidation of motor learning in older adults are limited to motor sequence tasks. To examine whether reduced sleep-dependent consolidation in older adults is generalizable to other forms of motor skill learning, we examined performance changes over intervals of sleep and wake in young (n = 62) and older adults (n = 61) using a mirror-tracing task, which assesses visuo-motor adaptation learning. Participants learned the task either in the morning or in evening, and performance was assessed following a 12-h interval containing overnight sleep or daytime wake. Contrary to our prediction, both young adults and older adults exhibited sleep-dependent gains in visuo-motor adaptation. There was a correlation between performance improvement over sleep and percent of the night in non-REM stage 2 sleep. These results indicate that motor skill consolidation remains intact with increasing age although this relationship may be limited to specific forms of motor skill learning.

  8. Stimulating the cerebellum affects visuomotor adaptation but not intermanual transfer of learning.

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    Block, Hannah; Celnik, Pablo

    2013-12-01

    When systematic movement errors occur, the brain responds with a systematic change in motor behavior. This type of adaptive motor learning can transfer intermanually; adaptation of movements of the right hand in response to training with a perturbed visual signal (visuomotor adaptation) may carry over to the left hand. While visuomotor adaptation has been studied extensively, it is unclear whether the cerebellum, a structure involved in adaptation, is important for intermanual transfer as well. We addressed this question with three experiments in which subjects reached with their right hands as a 30° visuomotor rotation was introduced. Subjects received anodal or sham transcranial direct current stimulation on the trained (experiment 1) or untrained (experiment 2) hemisphere of the cerebellum, or, for comparison, motor cortex (M1). After the training period, subjects reached with their left hand, without visual feedback, to assess intermanual transfer of learning aftereffects. Stimulation of the right cerebellum caused faster adaptation, but none of the stimulation sites affected transfer. To ascertain whether cerebellar stimulation would increase transfer if subjects learned faster as well as a larger amount, in experiment 3 anodal and sham cerebellar groups experienced a shortened training block such that the anodal group learned more than sham. Despite the difference in adaptation magnitude, transfer was similar across these groups, although smaller than in experiment 1. Our results suggest that intermanual transfer of visuomotor learning does not depend on cerebellar activity and that the number of movements performed at plateau is an important predictor of transfer.

  9. The effects of smooth pursuit adaptation on the gain of visuomotor transmission in monkeys

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    Seiji eOno

    2013-12-01

    Full Text Available Smooth pursuit eye movements are supported by visual-motor systems, where visual motion information is transformed into eye movement commands. Adaptation of the visuomotor systems for smooth pursuit is an important factor to maintain pursuit accuracy and high acuity vision. Short-term adaptation of initial pursuit gain can be produced experimentally using by repeated trials of a step-ramp tracking with two different velocities (double-step paradigm that step-up (10–30 °/s or step-down (20–5 °/s. It is also known that visuomotor gain during smooth pursuit is regulated by a dynamic gain control mechanism by showing that eye velocity evoked by a target perturbation during pursuit increases bidirectionally when ongoing pursuit velocity is higher. However, it remains uncertain how smooth pursuit adaptation alters the gain of visuomotor transmission. Therefore, a single cycle of sinusoidal motion (2.5 Hz, ± 10 °/s was introduced during step-ramp tracking pre- and post-adaptation to determine whether smooth pursuit adaptation affects the perturbation response. The results showed that pursuit adaptation had a significant effect on the perturbation response that was specific to the adapted direction. These results indicate that there might be different visuomotor mechanisms between adaptation and dynamic gain control. Furthermore, smooth pursuit adaptation altered not only the gain of the perturbation response, but also the gain slope (regression curve at different target velocities (5, 10 and 15 °/s. Therefore, pursuit adaptation could affect the dynamic regulation of the visuomotor gain at different pursuit velocities.

  10. Visuomotor adaptation of voluntary step initiation in older adults.

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    Tseng, Shih-Chiao; Stanhope, Steven J; Morton, Susanne M

    2010-02-01

    It has been suggested that feedforward planning of gait and posture is diminished in older adults. Motor adaptation is one mechanism by which feedforward commands can be updated or fine-tuned. Thus, if feedforward mechanisms are diminished in older adults, motor adaptation is also likely to be limited. The purpose of the study was to compare the ability of healthy older versus young adults in generating a voluntary stepping motor adaptation in response to a novel visual sensory perturbation. We recorded stepping movements from 18 healthy older and 18 young adults during baseline and adaptation stepping blocks. During baseline, the stepping target remained stationary; in adaptation, a visual perturbation was introduced by shifting the target laterally during mid-step. We compared adaptation between groups, measured by improvements in endpoint accuracy and movement duration. Older adults adapted stepping accuracy similarly to young adults (accuracy improvement: 29.7 + or - 27.6% vs. 37.3 + or - 22.9%, older vs. young group respectively, p = 0.375), but showed significant slowness during movement. Thus older adults were able to achieve accuracy levels nearly equivalent to younger adults, but only at the expense of movement speed, at least during the early adaptation period (movement duration: 1143.7 + or - 170.6 ms vs. 956.0 + or - 74.6 ms, p adults. These findings suggest older adults may retain the ability for stepping adaptations to environmental changes or novel demands, given sufficient practice. Copyright 2009 Elsevier B.V. All rights reserved.

  11. Elasticity improves handgrip performance and user experience during visuomotor control.

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    Mace, Michael; Rinne, Paul; Liardon, Jean-Luc; Uhomoibhi, Catherine; Bentley, Paul; Burdet, Etienne

    2017-02-01

    Passive rehabilitation devices, providing motivation and feedback, potentially offer an automated and low-cost therapy method, and can be used as simple human-machine interfaces. Here, we ask whether there is any advantage for a hand-training device to be elastic, as opposed to rigid, in terms of performance and preference. To address this question, we have developed a highly sensitive and portable digital handgrip, promoting independent and repetitive rehabilitation of grasp function based around a novel elastic force and position sensing structure. A usability study was performed on 66 healthy subjects to assess the effect of elastic versus rigid handgrip control during various visuomotor tracking tasks. The results indicate that, for tasks relying either on feedforward or on feedback control, novice users perform significantly better with the elastic handgrip, compared with the rigid equivalent (11% relative improvement, 9-14% mean range; p design consideration for grip training devices.

  12. Online Adaptation and Over-Trial Learning in Macaque Visuomotor Control

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    Braun, Daniel A.; Aertsen, Ad; Paz, Rony; Vaadia, Eilon; Rotter, Stefan; Mehring, Carsten

    2011-01-01

    When faced with unpredictable environments, the human motor system has been shown to develop optimized adaptation strategies that allow for online adaptation during the control process. Such online adaptation is to be contrasted to slower over-trial learning that corresponds to a trial-by-trial update of the movement plan. Here we investigate the interplay of both processes, i.e., online adaptation and over-trial learning, in a visuomotor experiment performed by macaques. We show that simple non-adaptive control schemes fail to perform in this task, but that a previously suggested adaptive optimal feedback control model can explain the observed behavior. We also show that over-trial learning as seen in learning and aftereffect curves can be explained by learning in a radial basis function network. Our results suggest that both the process of over-trial learning and the process of online adaptation are crucial to understand visuomotor learning. PMID:21720526

  13. A possible correlation between performance IQ, visuomotor adaptation ability and mu suppression.

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    Anwar, Muhammad Nabeel; Navid, Muhammad Samran; Khan, Mushtaq; Kitajo, Keiichi

    2015-04-07

    Psychometric, anatomical and functional brain studies suggest that individuals differ in the way that they perceive and analyze information and strategically control and execute movements. Inter-individual differences are also observed in neural correlates of specific and general cognitive ability. As a result, some individuals perceive and adapt to environmental conditions and perform motor activities better than others. The aim of this study was to identify a common factor that predicts adaptation of a reaching movement to a visual perturbation and suppression of movement-related brain activity (mu rhythms). Twenty-eight participants participated in two different experiments designed to evaluate visuomotor adaptation and mu suppression ability. Performance intelligence quotient (IQ) was assessed using the revised Wechsler Adult Intelligence Scale. Performance IQ predicted adaptation index of visuomotor performance (r=0.43, p=0.02) and suppression of mu rhythms (r=-0.59; pIQ were faster at adapting to a visuomotor perturbation and better at suppressing mu activity than participants with low performance IQ. We found a possible link between performance IQ and mu suppression, and performance IQ and the initial rate of adaptation. Individuals with high performance IQ were better in suppressing mu rhythms and were quicker at associating motor command and required movement than individuals with low performance IQ. Copyright © 2015 Elsevier B.V. All rights reserved.

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

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    Miya K Rand

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

  15. Consolidation through the looking-glass: sleep-dependent proactive interference on visuomotor adaptation in children.

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    Urbain, Charline; Houyoux, Emeline; Albouy, Geneviève; Peigneux, Philippe

    2014-02-01

    Although a beneficial role of post-training sleep for declarative memory has been consistently evidenced in children, as in adults, available data suggest that procedural memory consolidation does not benefit from sleep in children. However, besides the absence of performance gains in children, sleep-dependent plasticity processes involved in procedural memory consolidation might be expressed through differential interference effects on the learning of novel but related procedural material. To test this hypothesis, 32 10-12-year-old children were trained on a motor rotation adaptation task. After either a sleep or a wake period, they were first retested on the same rotation applied at learning, thus assessing offline sleep-dependent changes in performance, then on the opposite (unlearned) rotation to assess sleep-dependent modulations in proactive interference coming from the consolidated visuomotor memory trace. Results show that children gradually improve performance over the learning session, showing effective adaptation to the imposed rotation. In line with previous findings, no sleep-dependent changes in performance were observed for the learned rotation. However, presentation of the opposite, unlearned deviation elicited significantly higher interference effects after post-training sleep than wakefulness in children. Considering that a definite feature of procedural motor memory and skill acquisition is the implementation of highly automatized motor behaviour, thus lacking flexibility, our results suggest a better integration and/or automation or motor adaptation skills after post-training sleep, eventually resulting in higher proactive interference effects on untrained material. © 2013 European Sleep Research Society.

  16. The role of cognition for different stages of visuomotor adaptation in younger and older adults.

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    Simon, Anja; Bock, Otmar

    2017-04-01

    A recent model identified three stages of learning, the first drawing on cognitive flexibility, the second on inhibition, and the third on automation. We explored the validity of this model for visuomotor learning and found that adaptation is associated with inhibition early during adaptation and with automaticity later on. An initial association with cognitive flexibility remained inconclusive. This work employs another marker of cognitive flexibility and extends our work to older adults. Twenty young and 20 older adults completed three cognitive tasks (switch task, Stroop task and four-choice-reaction-time-task). They performed a visuomotor adaptation task under 60° rotation of visual feedback. Based on their cognitive scores, participants were divided into good and poor performers. Young adults outperformed older adults in visuomotor adaptation tasks and in cognitive tasks. Switch task performance was not associated with adaptation in either age group. Stroop performance was associated with early and four-choice-reaction-time-task with late adaptation in young adults. In older adults, Stroop performance was associated with early as well as late adaptation whereas four-choice-reaction-time-task was not associated with adaptation. All associations were present during adaptation, but not during de-adaptation. Our findings do not confirm the existence of the first postulated learning stage for the case of adaptation. They support the second and third stage in young persons for strategical components of adaptation. In older adults, the duration of the second stage seems to extend so that the third stage was not reached within the duration of our experiment. We conclude that degraded cognition in older age could explain why adaptation is impaired while aftereffects remain intact. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Parkinson’s Disease Differentially Affects Adaptation to Gradual as Compared to Sudden Visuomotor Distortions

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    Venkatakrishnan, Anusha; Banquet, Jean P.; Burnod, Yves; Contreras-Vidal, José L.

    2011-01-01

    Patients with Parkinson’s disease (PD) have difficulties in movement adaptation to optimize performance in novel environmental contexts such as altered screen cursor-hand relationships. Prior studies have shown that the time course of the distortion differentially affects visuomotor adaptation to screen cursor rotations, suggesting separate mechanisms for gradual and sudden adaptation. Moreover, studies in human and non-human primates suggest that adaptation to sudden kinematic distortions may engage the basal ganglia, whereas adaptation to gradual kinematic distortions involves cerebellar structures. In the present studies, participants were patients with PD, who performed center-out pointing movements, using either a digitizer tablet and pen or a computer trackball, under normal or rotated screen cursor feedback conditions. The initial study tested patients with PD using a cross-over experimental design for adaptation to gradual as compared with sudden rotated hand-screen cursor relationships and revealed significant after-effects for the gradual adaptation task only. Consistent with these results, findings from a follow-up experiment using a trackball that required only small finger movements showed that patients with PD adapt better to gradual as against sudden perturbations, when compared to age-matched healthy controls. We conclude that Parkinson’s disease affects adaptation to sudden visuomotor distortions but spares adaptation to gradual distortions. PMID:21414678

  18. Sleep-dependent improvement in visuomotor learning: a causal role for slow waves.

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    Landsness, Eric C; Crupi, Domenica; Hulse, Brad K; Peterson, Michael J; Huber, Reto; Ansari, Hidayath; Coen, Michael; Cirelli, Chiara; Benca, Ruth M; Ghilardi, M Felice; Tononi, Giulio

    2009-10-01

    Sleep after learning often benefits memory consolidation, but the underlying mechanisms remain unclear. In previous studies, we found that learning a visuomotor task is followed by an increase in sleep slow wave activity (SWA, the electroencephalographic [EEG] power density between 0.5 and 4.5 Hz during non-rapid eye movement sleep) over the right parietal cortex. The SWA increase correlates with the postsleep improvement in visuomotor performance, suggesting that SWA may be causally responsible for the consolidation of visuomotor learning. Here, we tested this hypothesis by studying the effects of slow wave deprivation (SWD). After learning the task, subjects went to sleep, and acoustic stimuli were timed either to suppress slow waves (SWD) or to interfere as little as possible with spontaneous slow waves (control acoustic stimulation, CAS). Sound-attenuated research room. Healthy subjects (mean age 24.6 +/- 1.0 years; n = 9 for EEG analysis, n = 12 for behavior analysis; 3 women). Sleep time and efficiency were not affected, whereas SWA and the number of slow waves decreased in SWD relative to CAS. Relative to the night before, visuomotor performance significantly improved in the CAS condition (+5.93% +/- 0.88%) but not in the SWD condition (-0.77% +/- 1.16%), and the direct CAS vs SWD comparison showed a significant difference (P = 0.0007, n = 12, paired t test). Changes in visuomotor performance after SWD were correlated with SWA changes over right parietal cortex but not with the number of arousals identified using clinically established criteria, nor with any sign of "EEG lightening" identified using a novel automatic method based on event-related spectral perturbation analysis. These results support a causal role for sleep slow waves in sleep-dependent improvement of visuomotor performance.

  19. Generalization patterns for reach adaptation and proprioceptive recalibration differ after visuomotor learning

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    Cressman, Erin K.

    2015-01-01

    Visuomotor learning results in changes in both motor and sensory systems (Cressman EK, Henriques DY. J Neurophysiol 102: 3505–3518, 2009), such that reaches are adapted and sense of felt hand position recalibrated after reaching with altered visual feedback of the hand. Moreover, visuomotor learning has been shown to generalize such that reach adaptation achieved at a trained target location can influence reaches to novel target directions (Krakauer JW, Pine ZM, Ghilardi MF, Ghez C. J Neurosci 20: 8916–8924, 2000). We looked to determine whether proprioceptive recalibration also generalizes to novel locations. Moreover, we looked to establish the relationship between reach adaptation and changes in sense of felt hand position by determining whether proprioceptive recalibration generalizes to novel targets in a similar manner as reach adaptation. On training trials, subjects reached to a single target with aligned or misaligned cursor-hand feedback, in which the cursor was either rotated or scaled in extent relative to hand movement. After reach training, subjects reached to the training target and novel targets (including targets from a second start position) without visual feedback to assess generalization of reach adaptation. Subjects then performed a proprioceptive estimation task, in which they indicated the position of their hand relative to visual reference markers placed at similar locations as the trained and novel reach targets. Results indicated that shifts in hand position generalized across novel locations, independent of reach adaptation. Thus these distinct sensory and motor generalization patterns suggest that reach adaptation and proprioceptive recalibration arise from independent error signals and that changes in one system cannot guide adjustments in the other. PMID:25972587

  20. Flexible explicit but rigid implicit learning in a visuomotor adaptation task

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    Bond, Krista M.

    2015-01-01

    There is mounting evidence for the idea that performance in a visuomotor rotation task can be supported by both implicit and explicit forms of learning. The implicit component of learning has been well characterized in previous experiments and is thought to arise from the adaptation of an internal model driven by sensorimotor prediction errors. However, the role of explicit learning is less clear, and previous investigations aimed at characterizing the explicit component have relied on indirect measures such as dual-task manipulations, posttests, and descriptive computational models. To address this problem, we developed a new method for directly assaying explicit learning by having participants verbally report their intended aiming direction on each trial. While our previous research employing this method has demonstrated the possibility of measuring explicit learning over the course of training, it was only tested over a limited scope of manipulations common to visuomotor rotation tasks. In the present study, we sought to better characterize explicit and implicit learning over a wider range of task conditions. We tested how explicit and implicit learning change as a function of the specific visual landmarks used to probe explicit learning, the number of training targets, and the size of the rotation. We found that explicit learning was remarkably flexible, responding appropriately to task demands. In contrast, implicit learning was strikingly rigid, with each task condition producing a similar degree of implicit learning. These results suggest that explicit learning is a fundamental component of motor learning and has been overlooked or conflated in previous visuomotor tasks. PMID:25855690

  1. Visuomotor adaptation needs a validation of prediction error by feedback error

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    Valérie eGaveau

    2014-11-01

    Full Text Available The processes underlying short-term plasticity induced by visuomotor adaptation to a shifted visual field are still debated. Two main sources of error can induce motor adaptation: reaching feedback errors, which correspond to visually perceived discrepancies between hand and target positions, and errors between predicted and actual visual reafferences of the moving hand. These two sources of error are closely intertwined and difficult to disentangle, as both the target and the reaching limb are simultaneously visible. Accordingly, the goal of the present study was to clarify the relative contributions of these two types of errors during a pointing task under prism-displaced vision. In ‘terminal feedback error’ condition, viewing of their hand by subjects was allowed only at movement end, simultaneously with viewing of the target. In ‘movement prediction error’ condition, viewing of the hand was limited to movement duration, in the absence of any visual target, and error signals arose solely from comparisons between predicted and actual reafferences of the hand. In order to prevent intentional corrections of errors, a subthreshold, progressive stepwise increase in prism deviation was used, so that subjects remained unaware of the visual deviation applied in both conditions. An adaptive aftereffect was observed in the ‘terminal feedback error’ condition only. As far as subjects remained unaware of the optical deviation and self-assigned pointing errors, prediction error alone was insufficient to induce adaptation. These results indicate a critical role of hand-to-target feedback error signals in visuomotor adaptation; consistent with recent neurophysiological findings, they suggest that a combination of feedback and prediction error signals is necessary for eliciting aftereffects. They also suggest that feedback error updates the prediction of reafferences when a visual perturbation is introduced gradually and cognitive factors are

  2. Both movement-end and task-end are critical for error feedback in visuomotor adaptation: a behavioral experiment.

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    Takumi Ishikawa

    Full Text Available An important issue in motor learning/adaptation research is how the brain accepts the error information necessary for maintaining and improving task performance in a changing environment. The present study focuses on the effect of timing of error feedback. Previous research has demonstrated that adaptation to displacement of the visual field by prisms in a manual reaching task is significantly slowed by delayed visual feedback of the endpoint, suggesting that error feedback is most effective when given at the end of a movement. To further elucidate the brain mechanism by which error information is accepted in visuomotor adaptation, we tested whether error acceptance is linked to the end of a given task or to the end of an executed movement. We conducted a behavioral experiment using a virtual shooting task in which subjects controlled their wrist movements to meet a target with a cursor as accurately as possible. We manipulated the timing of visual feedback of the impact position so that it occurred either ahead of or behind the true time of impact. In another condition, the impact timing was explicitly indicated by an additional cue. The magnitude of the aftereffect significantly varied depending on the timing of feedback (p < 0.05, Friedman's Test. Interestingly, two distinct peaks of aftereffect were observed around movement-end and around task-end, irrespective of the existence of the timing cue. However, the peak around task-end was sharper when the timing cue was given. Our results demonstrate that the brain efficiently accepts error information at both movement-end and task-end, suggesting that two different learning mechanisms may underlie visuomotor transformation.

  3. Gaze locations affect explicit process but not implicit process during visuomotor adaptation.

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    Rand, Miya K; Rentsch, Sebastian

    2015-01-01

    The role of vision in implicit and explicit processes involved in adaptation to novel visuomotor transformations is not well-understood. We manipulated subjects' gaze locations through instructions during a visuomotor rotation task that established a conflict between implicit and explicit processes. Subjects were informed of a rotated visual feedback (45° counterclockwise from the desired target) and instructed to counteract it by using an explicit aiming strategy to the neighboring target (45° clockwise from the target). Simultaneously, they were instructed to gaze at either the desired target (target-gaze group), the neighboring target (hand-target-gaze group), or anywhere (free-gaze group) during aiming. After initial elimination of behavioral errors caused by strategic aiming, the subjects gradually overcompensated the rotation in the early practice, thereby increasing behavioral errors (i.e., a drift). This was caused by an implicit adaptation overriding the explicit strategy. Notably, prescribed gaze locations did not affect this implicit adaptation. In the late practice, the target-gaze and free-gaze groups reduced the drift, whereas the hand-target-gaze group did not. Furthermore, the free-gaze group changed gaze locations for strategic aiming through practice from the neighboring target to the desired target. The onset of this change was correlated with the onset of the drift reduction. These results suggest that gaze locations critically affect explicit adjustments of aiming directions to reduce the drift by taking into account the implicit adaptation that is occurring in parallel. Taken together, spatial eye-hand coordination that ties the gaze and the reach target influences the explicit process but not the implicit process. Copyright © 2015 the American Physiological Society.

  4. Eye-Hand Coordination during Visuomotor Adaptation with Different Rotation Angles

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    Rentsch, Sebastian; Rand, Miya K.

    2014-01-01

    This study examined adaptive changes of eye-hand coordination during a visuomotor rotation task. Young adults made aiming movements to targets on a horizontal plane, while looking at the rotated feedback (cursor) of hand movements on a monitor. To vary the task difficulty, three rotation angles (30°, 75°, and 150°) were tested in three groups. All groups shortened hand movement time and trajectory length with practice. However, control strategies used were different among groups. The 30° group used proportionately more implicit adjustments of hand movements than other groups. The 75° group used more on-line feedback control, whereas the 150° group used explicit strategic adjustments. Regarding eye-hand coordination, timing of gaze shift to the target was gradually changed with practice from the late to early phase of hand movements in all groups, indicating an emerging gaze-anchoring behavior. Gaze locations prior to the gaze anchoring were also modified with practice from the cursor vicinity to an area between the starting position and the target. Reflecting various task difficulties, these changes occurred fastest in the 30° group, followed by the 75° group. The 150° group persisted in gazing at the cursor vicinity. These results suggest that the function of gaze control during visuomotor adaptation changes from a reactive control for exploring the relation between cursor and hand movements to a predictive control for guiding the hand to the task goal. That gaze-anchoring behavior emerged in all groups despite various control strategies indicates a generality of this adaptive pattern for eye-hand coordination in goal-directed actions. PMID:25333942

  5. Eye-hand coordination during visuomotor adaptation with different rotation angles.

    Directory of Open Access Journals (Sweden)

    Sebastian Rentsch

    Full Text Available This study examined adaptive changes of eye-hand coordination during a visuomotor rotation task. Young adults made aiming movements to targets on a horizontal plane, while looking at the rotated feedback (cursor of hand movements on a monitor. To vary the task difficulty, three rotation angles (30°, 75°, and 150° were tested in three groups. All groups shortened hand movement time and trajectory length with practice. However, control strategies used were different among groups. The 30° group used proportionately more implicit adjustments of hand movements than other groups. The 75° group used more on-line feedback control, whereas the 150° group used explicit strategic adjustments. Regarding eye-hand coordination, timing of gaze shift to the target was gradually changed with practice from the late to early phase of hand movements in all groups, indicating an emerging gaze-anchoring behavior. Gaze locations prior to the gaze anchoring were also modified with practice from the cursor vicinity to an area between the starting position and the target. Reflecting various task difficulties, these changes occurred fastest in the 30° group, followed by the 75° group. The 150° group persisted in gazing at the cursor vicinity. These results suggest that the function of gaze control during visuomotor adaptation changes from a reactive control for exploring the relation between cursor and hand movements to a predictive control for guiding the hand to the task goal. That gaze-anchoring behavior emerged in all groups despite various control strategies indicates a generality of this adaptive pattern for eye-hand coordination in goal-directed actions.

  6. Neural Predictors of Visuomotor Adaptation Rate and Multi-Day Savings

    Science.gov (United States)

    Cassady, Kaitlin; Ruitenberg, Marit; Koppelmans, Vincent; Reuter-Lorenz, Patricia; De Dios, Yiri; Gadd, Nichole; Wood, Scott; Riascos Castenada, Roy; Kofman, Igor; Bloomberg, Jacob; hide

    2017-01-01

    Recent studies of sensorimotor adaptation have found that individual differences in task-based functional brain activation are associated with the rate of adaptation and savings at subsequent sessions. However, few studies to date have investigated offline neural predictors of adaptation and multi-day savings. In the present study, we explore whether individual differences in the rate of visuomotor adaptation and multi-day savings are associated with differences in resting state functional connectivity and gray matter volume. Thirty-four participants performed a manual adaptation task during two separate test sessions, on average 9 days apart. We found that resting state functional connectivity strength between sensorimotor, anterior cingulate, and temporoparietal areas of the brain was a significant predictor of adaptation rate during the early, cognitive phase of practice. In contrast, default mode network functional connectivity strength was found to predict late adaptation rate and savings on day two, which suggests that these behaviors may rely on overlapping processes. We also found that gray matter volume in temporoparietal and occipital regions was a significant predictor of early learning, whereas gray matter volume in superior posterior regions of the cerebellum was a significant predictor of late adaptation. The results from this study suggest that offline neural predictors of early adaptation facilitate the cognitive mechanisms of sensorimotor adaptation, with support from by the involvement of temporoparietal and cingulate networks. In contrast, the neural predictors of late adaptation and savings, including the default mode network and the cerebellum, likely support the storage and modification of newly acquired sensorimotor representations. These findings provide novel insights into the neural processes associated with individual differences in sensorimotor adaptation.

  7. The rate of visuomotor adaptation correlates with cerebellar white-matter microstructure.

    Science.gov (United States)

    Della-Maggiore, Valeria; Scholz, Jan; Johansen-Berg, Heidi; Paus, Tomás

    2009-12-01

    Convergent experimental evidence points to the cerebellum as a key neural structure mediating adaptation to visual and proprioceptive perturbations. In a previous study, we have shown that activity in the anterior cerebellum varies with the rate of learning, with fast learners exhibiting more activity in this region than slow learners. Here, we investigated whether this variability in behavior may partly reflect inter-individual differences in the structural properties of cerebellar white-matter output tracts. For this purpose, we used diffusion-weighted magnetic resonance imaging to estimate fractional anisotropy (FA), and correlated the FA with the rate of adaptation to an optical rotation in 11 subjects. We found that FA in a region consistent with the superior cerebellar peduncle (SCP), containing fibers connecting the cerebellar cortex with motor and premotor cortex, was positively correlated with the rate of adaptation but not with the general level of performance or the initial deviation. The same pattern was observed in a region of the lateral posterior cerebellum. In contrast, FA in the angular gyrus of the posterior parietal cortex correlated positively both with the rate of adaptation and the overall level of performance. Our results show that the rate of learning a visuomotor task is associated with FA of cerebellar pathways. 2009 Wiley-Liss, Inc.

  8. Daytime sleep has no effect on the time course of motor sequence and visuomotor adaptation learning.

    Science.gov (United States)

    Backhaus, Winifried; Braaß, Hanna; Renné, Thomas; Krüger, Christian; Gerloff, Christian; Hummel, Friedhelm C

    2016-05-01

    Sleep has previously been claimed to be essential for the continued learning processes of declarative information as well as procedural learning. This study was conducted to examine the importance of sleep, especially the effects of midday naps, on motor sequence and visuomotor adaptation learning. Thirty-five (27 females) healthy, young adults aged between 18 and 30years of age participated in the current study. Addressing potential differences in explicit sequence and motor adaptation learning participants were asked to learn both, a nine-element explicit sequence and a motor adaptation task, in a crossover fashion on two consecutive days. Both tasks were performed with their non-dominant left hand. Prior to learning, each participant was randomized to one of three interventions; (1) power nap: 10-20min sleep, (2) long nap: 50-80min sleep or (3) a 45-min wake-condition. Performance of the motor learning task took place prior to and after a midday rest period, as well as after a night of sleep. Both sleep conditions were dominated by Stage N2 sleep with embedded sleep spindles, which have been described to be associated with enhancement of motor performance. Significant performance changes were observed in both tasks across all interventions (sleep and wake) confirming that learning took place. In the present setup, the magnitude of motor learning was not sleep-dependent in young adults - no differences between the intervention groups (short nap, long nap, no nap) could be found. The effect of the following night of sleep was not influenced by the previous midday rest or sleep period. This finding may be related to the selectiveness of the human brain enhancing especially memory being thought of as important in the future. Previous findings on motor learning enhancing effects of sleep, especially of daytime sleep, are challenged. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Improved human visuomotor performance and pupil constriction after choline supplementation in a placebo-controlled double-blind study

    NARCIS (Netherlands)

    Naber, M.; Hommel, Bernhard; Colzato, Lorenza

    2015-01-01

    Only few nutrients are known to enhance cognition. Here we explore whether visuomotor performance can be improved through the intake of the nutrient choline, an essential chemical compound in a vertebrate’s diet. Choline is abundant in for example eggs and shrimps and many animal studies suggest

  10. Age-related variations of visuomotor adaptation result from both the acquisition and the application of explicit knowledge.

    Science.gov (United States)

    Hegele, Mathias; Heuer, Herbert

    2013-06-01

    The present study aimed to assess whether age-related differences in visuomotor adaptation are limited to the acquisition of explicit knowledge or extend to the application of the explicit knowledge in terms of deliberate strategic corrections. Old and young participants performed aiming movements, controlling a cursor on a computer screen with rotated visual feedback. Participants either received an explicit pretraining of the rotation or practiced a similar task that was unrelated to the upcoming rotation. Results show an age-related difference in the application of explicit knowledge and thereby extend previous findings of age-related differences in the acquisition of explicit knowledge. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  11. Probability differently modulating the effects of reward and punishment on visuomotor adaptation.

    Science.gov (United States)

    Song, Yanlong; Smiley-Oyen, Ann L

    2017-12-01

    Recent human motor learning studies revealed that punishment seemingly accelerated motor learning but reward enhanced consolidation of motor memory. It is not evident how intrinsic properties of reward and punishment modulate the potentially dissociable effects of reward and punishment on motor learning and motor memory. It is also not clear what causes the dissociation of the effects of reward and punishment. By manipulating probability of distribution, a critical property of reward and punishment, the present study demonstrated that probability had distinct modulation on the effects of reward and punishment in adapting to a sudden visual rotation and consolidation of the adaptation memory. Specifically, two probabilities of monetary reward and punishment distribution, 50 and 100%, were applied during young adult participants adapting to a sudden visual rotation. Punishment and reward showed distinct effects on motor adaptation and motor memory. The group that received punishments in 100% of the adaptation trials adapted significantly faster than the other three groups, but the group that received rewards in 100% of the adaptation trials showed marked savings in re-adapting to the same rotation. In addition, the group that received punishments in 50% of the adaptation trials that were randomly selected also had savings in re-adapting to the same rotation. Sensitivity to sensory prediction error or difference in explicit process induced by reward and punishment may likely contribute to the distinct effects of reward and punishment.

  12. Longitudinal development of cognitive, visuomotor and adaptive behavior skills in HIV uninfected children, aged 3-5 years of age, exposed pre- and perinatally to anti-retroviral medications.

    Science.gov (United States)

    Smith, Mary Lou; Puka, Klajdi; Sehra, Ramandeep; Read, Stanley E; Bitnun, Ari

    2017-10-01

    Little is known about the neurodevelopmental outcomes of children older than 3 years of age born to HIV infected mother but who are HIV-uninfected (HEU), and who have been exposed in utero and early in life to HIV and to antiretroviral medications (ARVs). We conducted a longitudinal study of cognitive, visuomotor and adaptive function of HEU children, who were assessed at two ages, 3.5 and 5.5 years. Sixty-four children (33 female) were assessed. In comparison with population norms for their age, at 3.5 years of age they had scores significantly below age expectations on aspects of adaptive behavior, but at age 5.5 years, their scores did not significantly diverge from the population norms on any of the measures. Verbal intelligence was lower at age 5.5 than at age 3.5 years, although there were also improvements in some features of adaptive behavior. Exposure to PI-based ARVs (compared to NNRTIs) was associated with higher Performance IQ, visuomotor and communication scores at age 5.5 years. Birth, early growth, and sociodemographic variables were predictive of outcomes. This study is important in tracking the trajectory of neurocognitive development across the pre-school and early school age years. The findings suggest that the full impact of early ARV exposure may not be evident until a considerable period of development has occurred. The results raise the possibility of negative effects of early ARV exposure on neurodevelopment that emerge over time, and reiterate the importance of sociodemographic and early health variables for optimal development.

  13. Impaired visuomotor generalization by inconsistent attentional contexts.

    Science.gov (United States)

    Wang, Tony S L; Song, Joo-Hyun

    2017-09-01

    In daily life, people are constantly presented with situations in which they have to learn and acquire new motor skills in complex environments, where attention is often distracted by other events. Being able to generalize and perform the acquired motor action in different environments is a crucial part of visuomotor learning. The current study examined whether attentional distraction impairs generalization of visuomotor adaptation or whether consistent distraction can operate as an internal cue to facilitate generalization. Using a dual-task paradigm combining visuomotor rotational adaptation and an attention-demanding secondary task, we showed that switching the attentional context from training (dual-task) to generalization (single-task) reduced the range of transfer of visuomotor adaptation to untrained directions. However, when consistent distraction was present throughout training and generalization, visuomotor generalization was equivalent to without distractions at all. Furthermore, this attentional context-dependent generalization was evident even when sensory modality of distractions differed between training and generalization. Therefore, the general nature of the dual tasks, rather than the specific stimuli, is associated with visuomotor memory and serves as a critical cue for generalization. Taken together, we demonstrated that attention plays a critical role during sensorimotor adaptation in selecting and associating multisensory signals with motor memory. This finding provides insight into developing learning programs that are generalizable in complex daily environments.NEW & NOTEWORTHY Learning novel motor actions in complex environments with attentional distraction is a critical function. Successful motor learning involves the ability to transfer the acquired skill from the trained to novel environments. Here, we demonstrate attentional distraction does not impair visuomotor adaptation. Rather, consistency in the attentional context from training

  14. A robot-aided visuo-motor training that improves proprioception and spatial accuracy of untrained movement.

    Science.gov (United States)

    Elangovan, Naveen; Cappello, Leonardo; Masia, Lorenzo; Aman, Joshua; Konczak, Jürgen

    2017-12-06

    Proprioceptive function can become enhanced during motor learning. Yet, we have incomplete knowledge to what extent proprioceptive function is trainable and how a training that enhances proprioception may influence performance in untrained motor skills. To address this knowledge gap, healthy young adults (N = 14) trained in a visuomotor task that required learners to make increasingly accurate wrist movements. Using a robotic exoskeleton coupled with a virtual visual environment, participants tilted a virtual table through continuous wrist flexion/extension movements with the goal to position a rolling ball on table into a target. With learning progress, the level of difficulty increased by altering the virtual ball mechanics and the gain between joint movement and ball velocity. Before and after training, wrist position sense acuity and spatial movement accuracy in an untrained, discrete wrist-pointing task was assessed using the same robot. All participants showed evidence of proprioceptive-motor learning. Mean position sense discrimination threshold improved by 34%. Wrist movement accuracy in the untrained pointing task improved by 27% in 13/14 participants. This demonstrates that a short sensorimotor training challenging proprioception can a) effectively enhance proprioceptive acuity and b) improve the accuracy of untrained movement. These findings provide a scientific basis for applying such somatosensory-based motor training to clinical populations with known proprioceptive dysfunction to enhance sensorimotor performance.

  15. Contributions of Spatial Working Memory to Visuomotor Learning

    Science.gov (United States)

    Anguera, Joaquin A.; Reuter-Lorenz, Patricia A.; Willingham, Daniel T.; Seidler, Rachael D.

    2010-01-01

    Previous studies of motor learning have described the importance of cognitive processes during the early stages of learning; however, the precise nature of these processes and their neural correlates remains unclear. The present study investigated whether spatial working memory (SWM) contributes to visuomotor adaptation depending on the stage of…

  16. Interactive effects of visuomotor perturbation and an afternoon nap on performance and the flow experience.

    Directory of Open Access Journals (Sweden)

    Kosuke Kaida

    Full Text Available The present study was designed (1 to clarify the relationship between the flow experience and improvements in visuomotor skills, (2 to examine the effects of rotating the axis of a computer mouse on visuomotor skills, and (3 to investigate the effects of sleep for improving visuomotor skills. Participants (N = 18 responded to Perturbation and nap (PER+Nap, No-perturbation and nap (NoPER+Nap and Perturbation and rest (PER+Rest conditions. In the PER+Nap condition, participants conducted a visuomotor tracking task using a computer mouse, which was accompanied by perturbation caused by rotating the axis of their mouse. After the task, they took a 90 min nap. In NoPER+Nap condition, they conducted the same visuomotor task without any perturbation and took a nap. In the PER+Rest condition, participants conducted the task with the perturbation and took a 90 min break spent reading magazines instead of taking a nap. Results indicated (1 the flow experience did not occur when participants' skills and the degree of the visuomotor challenge were matching, (2 improvements of visuomotor skills occurred regardless of the perturbation, (3 improvements of visuomotor skills occurred unrelated to the flow experience, or to mood states, and (4 improvements of visuomotor performance occurred regardless of sleep. These findings suggest that improvements of visuomotor skills occur regardless of mood status and occur independently of perturbations by axis rotation. The study also suggests that the acquisition of skills is related to merely the time elapsed since learning, rather than to sleep.

  17. Differential effect of alcoholism and HIV infection on visuomotor procedural learning and retention.

    Science.gov (United States)

    Fama, Rosemary; Rosenbloom, Margaret J; Sassoon, Stephanie A; Pfefferbaum, Adolf; Sullivan, Edith V

    2012-10-01

    Selective declarative memory processes are differentially compromised in chronic alcoholism (ALC) and HIV infection (HIV) and likely reflect neuropathology associated with each condition: frontocerebellar dysfunction in ALC and frontostriatal dysfunction in HIV infection. Evidence for disease overlap derives from observed exacerbated impairments in these declarative memory processes in ALC-HIV comorbidity. Less is known about nondeclarative memory processes in these disease conditions. Examination of visuomotor learning in chronic ALC and HIV infection could provide insight into the differential and combined contribution of selective disease-related injury to visuomotor procedural memory processes. We examined component processes of visuomotor learning and retention on the rotary pursuit task in 29 ALC, 23 HIV, 28 ALC + HIV, and 20 control subjects. Participants were given 4 rotary pursuit learning sessions over 2 testing days, typically separated by 1 week, to assess visuomotor learning and retention patterns. Ancillary measures of simple motor, psychomotor, explicit memory, and balance abilities were administered to test which component processes independently predicted visuomotor learning. All clinical groups showed visuomotor learning across rotary pursuit testing sessions, despite impairment in visuomotor speed in the HIV groups and impairment in explicit memory and psychomotor speed in the alcohol groups. The 2 alcoholic groups showed retention and consolidation over time (i.e., improved performance without further training), whereas the HIV-infected group showed learning and retention but no consolidation effect. The comorbid group shared impairments associated with the ALC-only group (explicit memory and psychomotor speed) and the HIV-only group (visuomotor speed), although there was no clear compounded effect of alcohol and HIV infection on visuomotor learning performance. This study supports the hypothesis that ALC and HIV infection exert differential

  18. Evidence from Visuomotor Adaptation for Two Partially Independent Visuomotor Systems

    Science.gov (United States)

    Thaler, Lore; Todd, James T.

    2010-01-01

    Visual information can specify spatial layout with respect to the observer (egocentric) or with respect to an external frame of reference (allocentric). People can use both of these types of visual spatial information to guide their hands. The question arises if movements based on egocentric and movements based on allocentric visual information…

  19. Action Video Game Playing Is Reflected In Enhanced Visuomotor Performance and Increased Corticospinal Excitability

    OpenAIRE

    Morin-Moncet, Olivier; Therrien-Blanchet, Jean-Marc; Ferland, Marie C.; Th?oret, Hugo; West, Greg L.

    2016-01-01

    Action video game playing is associated with improved visuomotor performance; however, the underlying neural mechanisms associated with this increased performance are not well understood. Using the Serial Reaction Time Task in conjunction with Transcranial Magnetic Stimulation, we investigated if improved visuomotor performance displayed in action video game players (actionVGPs) was associated with increased corticospinal plasticity in primary motor cortex (M1) compared to non-video game play...

  20. Effects of normal aging on visuo-motor plasticity

    Science.gov (United States)

    Roller, Carrie A.; Cohen, Helen S.; Kimball, Kay T.; Bloomberg, Jacob J.

    2002-01-01

    Normal aging is associated with declines in neurologic function. Uncompensated visual and vestibular problems may have dire consequences including dangerous falls. Visuo-motor plasticity is a form of behavioral neural plasticity, which is important in the process of adapting to visual or vestibular alteration, including those changes due to pathology, pharmacotherapy, surgery or even entry into microgravity or an underwater environment. To determine the effects of aging on visuo-motor plasticity, we chose the simple and easily measured paradigm of visual-motor rearrangement created by using visual displacement prisms while throwing small balls at a target. Subjects threw balls before, during and after wearing a set of prisms which displace the visual scene by twenty degrees to the right. Data obtained during adaptation were modeled using multilevel modeling techniques for 73 subjects, aged 20 to 80 years. We found no statistically significant difference in measures of visuo-motor plasticity with advancing age. Further studies are underway examining variable practice training as a potential mechanism for enhancing this form of behavioral neural plasticity.

  1. Generalization of stochastic visuomotor rotations.

    Directory of Open Access Journals (Sweden)

    Hugo L Fernandes

    Full Text Available Generalization studies examine the influence of perturbations imposed on one movement onto other movements. The strength of generalization is traditionally interpreted as a reflection of the similarity of the underlying neural representations. Uncertainty fundamentally affects both sensory integration and learning and is at the heart of many theories of neural representation. However, little is known about how uncertainty, resulting from variability in the environment, affects generalization curves. Here we extend standard movement generalization experiments to ask how uncertainty affects the generalization of visuomotor rotations. We find that although uncertainty affects how fast subjects learn, the perturbation generalizes independently of uncertainty.

  2. Generalization of Stochastic Visuomotor Rotations

    Science.gov (United States)

    Fernandes, Hugo L.; Stevenson, Ian H.; Kording, Konrad P.

    2012-01-01

    Generalization studies examine the influence of perturbations imposed on one movement onto other movements. The strength of generalization is traditionally interpreted as a reflection of the similarity of the underlying neural representations. Uncertainty fundamentally affects both sensory integration and learning and is at the heart of many theories of neural representation. However, little is known about how uncertainty, resulting from variability in the environment, affects generalization curves. Here we extend standard movement generalization experiments to ask how uncertainty affects the generalization of visuomotor rotations. We find that although uncertainty affects how fast subjects learn, the perturbation generalizes independently of uncertainty. PMID:22916198

  3. Influence of Internal and External Noise on Spontaneous Visuomotor Synchronization.

    Science.gov (United States)

    Varlet, Manuel; Schmidt, R C; Richardson, Michael J

    2016-01-01

    Historically, movement noise or variability is considered to be an undesirable property of biological motor systems. In particular, noise is typically assumed to degrade the emergence and stability of rhythmic motor synchronization. Recently, however, it has been suggested that small levels of noise might actually improve the functioning of motor systems and facilitate their adaptation to environmental events. Here, the authors investigated whether noise can facilitate spontaneous rhythmic visuomotor synchronization. They examined the influence of internal noise in the rhythmic limb movements of participants and external noise in the movement of an oscillating visual stimulus on the occurrence of spontaneous synchronization. By indexing the natural frequency variability of participants and manipulating the frequency variability of the visual stimulus, the authors demonstrated that both internal and external noise degrade synchronization when the participants' and stimulus movement frequencies are similar, but can actually facilitate synchronization when the frequencies are different. Furthermore, the two kinds of noise interact with each other. Internal noise facilitates synchronization only when external noise is minimal and vice versa. Too much internal and external noise together degrades synchronization. These findings open new perspectives for better understanding the role of noise in human rhythmic coordination.

  4. Improving Flood Plain Management through Adaptive Learning ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    This project will explore how an adaptive learning approach can improve CBO governance (transparency, equity, gender relations), generate new knowledge for improving resource sustainability and productivity, and facilitate learning and an exchange of experiences between CBOs, and between CBOs and policymakers.

  5. Abnormal visuomotor processing in schizophrenia

    Directory of Open Access Journals (Sweden)

    Siân E. Robson

    2016-01-01

    Full Text Available Subtle disturbances of visual and motor function are known features of schizophrenia and can greatly impact quality of life; however, few studies investigate these abnormalities using simple visuomotor stimuli. In healthy people, electrophysiological data show that beta band oscillations in sensorimotor cortex decrease during movement execution (event-related beta desynchronisation (ERBD, then increase above baseline for a short time after the movement (post-movement beta rebound (PMBR; whilst in visual cortex, gamma oscillations are increased throughout stimulus presentation. In this study, we used a self-paced visuomotor paradigm and magnetoencephalography (MEG to contrast these responses in patients with schizophrenia and control volunteers. We found significant reductions in the peak-to-peak change in amplitude from ERBD to PMBR in schizophrenia compared with controls. This effect was strongest in patients who made fewer movements, whereas beta was not modulated by movement in controls. There was no significant difference in the amplitude of visual gamma between patients and controls. These data demonstrate that clear abnormalities in basic sensorimotor processing in schizophrenia can be observed using a very simple MEG paradigm.

  6. Adapting to Climate Change through Improved Watershed ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Adapting to Climate Change through Improved Watershed Management and Payment for Environmental Services in Morocco's Tensift Basin ... Women in the developing world continue to face obstacles that limit their ability to establish careers and become leaders in the fields of science, technology, engineering, and ...

  7. Inferring visuomotor priors for sensorimotor learning.

    Directory of Open Access Journals (Sweden)

    Edward J A Turnham

    2011-03-01

    Full Text Available Sensorimotor learning has been shown to depend on both prior expectations and sensory evidence in a way that is consistent with Bayesian integration. Thus, prior beliefs play a key role during the learning process, especially when only ambiguous sensory information is available. Here we develop a novel technique to estimate the covariance structure of the prior over visuomotor transformations--the mapping between actual and visual location of the hand--during a learning task. Subjects performed reaching movements under multiple visuomotor transformations in which they received visual feedback of their hand position only at the end of the movement. After experiencing a particular transformation for one reach, subjects have insufficient information to determine the exact transformation, and so their second reach reflects a combination of their prior over visuomotor transformations and the sensory evidence from the first reach. We developed a Bayesian observer model in order to infer the covariance structure of the subjects' prior, which was found to give high probability to parameter settings consistent with visuomotor rotations. Therefore, although the set of visuomotor transformations experienced had little structure, the subjects had a strong tendency to interpret ambiguous sensory evidence as arising from rotation-like transformations. We then exposed the same subjects to a highly-structured set of visuomotor transformations, designed to be very different from the set of visuomotor rotations. During this exposure the prior was found to have changed significantly to have a covariance structure that no longer favored rotation-like transformations. In summary, we have developed a technique which can estimate the full covariance structure of a prior in a sensorimotor task and have shown that the prior over visuomotor transformations favor a rotation-like structure. Moreover, through experience of a novel task structure, participants can

  8. Environmental Adaptations Improve Everyday Action in Schizophrenia.

    Science.gov (United States)

    Kessler, Rachel K; Rhodes, Emma; Giovannetti, Tania

    2015-05-01

    Cognitive functioning, particularly executive functioning, is a strong predictor of functional outcomes in people with schizophrenia. Cognitive remediation has been shown to improve specific cognitive processes, but adjunctive interventions are required for meaningful gains in adaptive functioning, particularly in people with chronic illness. This study examined whether (and how) environmental adaptations, used without training, may circumvent cognitive difficulties and facilitate everyday task performance in individuals with chronic schizophrenia. Forty-two individuals with chronic schizophrenia/schizoaffective disorder were administered cognitive measures and two versions of the Naturalistic Action Test (NAT)-a standard version (ST-NAT), and a user-centered version (UC-NAT) that incorporated environmental adaptations designed to facilitate task performance. The NAT conditions were counterbalanced across participants. Analyses compared performance between the NAT versions and examined the cognitive correlates of each NAT condition. Individuals with schizophrenia made fewer errors on the UC-NAT as compared to the ST-NAT; this between-group difference was significant for all error types. Compared to the ST-NAT, the UC-NAT performance was not significantly associated with an executive function measure of planning. Environmental adaptations may be implemented without extensive training to improve everyday action in individuals with chronic schizophrenia. Environmental adaptations that reduce planning demands may be most effective in this population.

  9. An integrative framework of stress, attention, and visuomotor performance

    Directory of Open Access Journals (Sweden)

    Samuel James Vine

    2016-11-01

    Full Text Available The aim of this article is to present an integrative conceptual framework that depicts the effect of acute stress on the performance of visually guided motor skills. We draw upon seminal theories highlighting the importance of subjective interpretations of stress on subsequent performance and outline how models of disrupted attentional control might explain this effect through impairments in visuomotor control. We first synthesize and critically discuss empirical support for theories examining these relationships in isolation. We then outline our integrative framework that seeks to provide a more complete picture of the interacting influences of stress responses (challenge and threat and attention in explaining how elevated stress may lead to different visuomotor performance outcomes. We propose a number of mechanisms that explain why evaluations of stress are related to attentional control, and highlight the emotion of anxiety as the most likely candidate to explain why negative reactions to stress lead to disrupted attention and poor visuomotor skill performance. Finally, we propose a number of feedback loops that explain why stress responses are often self-perpetuating, as well as a number of proposed interventions that are designed to help improve or maintain performance in real world performance environments (e.g., sport, surgery, military, and aviation.

  10. An Adaptive Tutor for Improving Visual Diagnosis

    Science.gov (United States)

    2017-10-01

    AWARD NUMBER: W81XWH-16-1-0797 TITLE: An Adaptive Tutor for Improving Visual Diagnosis PRINCIPAL INVESTIGATOR: Martin V. Pusic, MD RECIPIENT... Visual Diagnosis 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-16-1-0797 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Martin V. Pusic – NYUSoM; David...for visual diagnosis can transcend institutional barriers to enable broad distribution of learning material. However, most current examples are based

  11. Improved LMS algorithm for adaptive beamforming

    Science.gov (United States)

    Godara, Lal C.

    1990-01-01

    Two adaptive algorithms which make use of all the available samples to estimate the required gradient are proposed and studied. The first algorithm is referred to as the recursive LMS (least mean squares) and is applicable to a general array. The second algorithm is referred to as the improved LMS algorithm and exploits the Toeplitz structure of the ACM (array correlation matrix); it can be used only for an equispaced linear array.

  12. Using brain potentials to understand prism adaptation: the error-related negativity and the P300

    Science.gov (United States)

    MacLean, Stephane J.; Hassall, Cameron D.; Ishigami, Yoko; Krigolson, Olav E.; Eskes, Gail A.

    2015-01-01

    Prism adaptation (PA) is both a perceptual-motor learning task as well as a promising rehabilitation tool for visuo-spatial neglect (VSN)—a spatial attention disorder often experienced after stroke resulting in slowed and/or inaccurate motor responses to contralesional targets. During PA, individuals are exposed to prism-induced shifts of the visual-field while performing a visuo-guided reaching task. After adaptation, with goggles removed, visuomotor responding is shifted to the opposite direction of that initially induced by the prisms. This visuomotor aftereffect has been used to study visuomotor learning and adaptation and has been applied clinically to reduce VSN severity by improving motor responding to stimuli in contralesional (usually left-sided) space. In order to optimize PA's use for VSN patients, it is important to elucidate the neural and cognitive processes that alter visuomotor function during PA. In the present study, healthy young adults underwent PA while event-related potentials (ERPs) were recorded at the termination of each reach (screen-touch), then binned according to accuracy (hit vs. miss) and phase of exposure block (early, middle, late). Results show that two ERP components were evoked by screen-touch: an error-related negativity (ERN), and a P300. The ERN was consistently evoked on miss trials during adaptation, while the P300 amplitude was largest during the early phase of adaptation for both hit and miss trials. This study provides evidence of two neural signals sensitive to visual feedback during PA that may sub-serve changes in visuomotor responding. Prior ERP research suggests that the ERN reflects an error processing system in medial-frontal cortex, while the P300 is suggested to reflect a system for context updating and learning. Future research is needed to elucidate the role of these ERP components in improving visuomotor responses among individuals with VSN. PMID:26124715

  13. Action Video Game Playing Is Reflected In Enhanced Visuomotor Performance and Increased Corticospinal Excitability.

    Science.gov (United States)

    Morin-Moncet, Olivier; Therrien-Blanchet, Jean-Marc; Ferland, Marie C; Théoret, Hugo; West, Greg L

    2016-01-01

    Action video game playing is associated with improved visuomotor performance; however, the underlying neural mechanisms associated with this increased performance are not well understood. Using the Serial Reaction Time Task in conjunction with Transcranial Magnetic Stimulation, we investigated if improved visuomotor performance displayed in action video game players (actionVGPs) was associated with increased corticospinal plasticity in primary motor cortex (M1) compared to non-video game players (nonVGPs). Further, we assessed if actionVGPs and nonVGPs displayed differences in procedural motor learning as measured by the SRTT. We found that at the behavioral level, both the actionVGPs and nonVGPs showed evidence of procedural learning with no significant difference between groups. However, the actionVGPs displayed higher visuomotor performance as evidenced by faster reaction times in the SRTT. This observed enhancement in visuomotor performance amongst actionVGPs was associated with increased corticospinal plasticity in M1, as measured by corticospinal excitability changes pre- and post- SRTT and corticospinal excitability at rest before motor practice. Our results show that aVGPs, who are known to have better performance on visual and motor tasks, also display increased corticospinal excitability after completing a novel visuomotor task.

  14. Action Video Game Playing Is Reflected In Enhanced Visuomotor Performance and Increased Corticospinal Excitability.

    Directory of Open Access Journals (Sweden)

    Olivier Morin-Moncet

    Full Text Available Action video game playing is associated with improved visuomotor performance; however, the underlying neural mechanisms associated with this increased performance are not well understood. Using the Serial Reaction Time Task in conjunction with Transcranial Magnetic Stimulation, we investigated if improved visuomotor performance displayed in action video game players (actionVGPs was associated with increased corticospinal plasticity in primary motor cortex (M1 compared to non-video game players (nonVGPs. Further, we assessed if actionVGPs and nonVGPs displayed differences in procedural motor learning as measured by the SRTT. We found that at the behavioral level, both the actionVGPs and nonVGPs showed evidence of procedural learning with no significant difference between groups. However, the actionVGPs displayed higher visuomotor performance as evidenced by faster reaction times in the SRTT. This observed enhancement in visuomotor performance amongst actionVGPs was associated with increased corticospinal plasticity in M1, as measured by corticospinal excitability changes pre- and post- SRTT and corticospinal excitability at rest before motor practice. Our results show that aVGPs, who are known to have better performance on visual and motor tasks, also display increased corticospinal excitability after completing a novel visuomotor task.

  15. Visuomotor cerebellum in human and nonhuman primates.

    Science.gov (United States)

    Voogd, Jan; Schraa-Tam, Caroline K L; van der Geest, Jos N; De Zeeuw, Chris I

    2012-06-01

    In this paper, we will review the anatomical components of the visuomotor cerebellum in human and, where possible, in non-human primates and discuss their function in relation to those of extracerebellar visuomotor regions with which they are connected. The floccular lobe, the dorsal paraflocculus, the oculomotor vermis, the uvula-nodulus, and the ansiform lobule are more or less independent components of the visuomotor cerebellum that are involved in different corticocerebellar and/or brain stem olivocerebellar loops. The floccular lobe and the oculomotor vermis share different mossy fiber inputs from the brain stem; the dorsal paraflocculus and the ansiform lobule receive corticopontine mossy fibers from postrolandic visual areas and the frontal eye fields, respectively. Of the visuomotor functions of the cerebellum, the vestibulo-ocular reflex is controlled by the floccular lobe; saccadic eye movements are controlled by the oculomotor vermis and ansiform lobule, while control of smooth pursuit involves all these cerebellar visuomotor regions. Functional imaging studies in humans further emphasize cerebellar involvement in visual reflexive eye movements and are discussed.

  16. Visuomotor resonance in autism spectrum disorders

    Directory of Open Access Journals (Sweden)

    Cristina eBecchio

    2012-11-01

    Full Text Available When we observe the actions performed by others, our motor system ‘resonates' along with that of the observed agent. Is a similar visuomotor resonant response observed in autism spectrum disorders (ASD? Studies investigating action observation in ASD have yielded inconsistent findings. In this perspective article we examine behavioral and neuroscientific evidence in favor of visuomotor resonance in ASD, and consider the possible role of action-perception coupling in social cognition. We distinguish between different aspects of visuomotor resonance and conclude that while some aspects may be preserved in ASD, abnormalities exist in the way individuals with ASD convert visual information from observed actions into a program for motor execution. Such abnormalities, we surmise, may contribute to but also depend on the difficulties that individuals with ASD encounter during social interaction.

  17. Improvement of Adaptive Cruise Control Performance

    Directory of Open Access Journals (Sweden)

    Nakagami Takashi

    2010-01-01

    Full Text Available This paper describes the Adaptive Cruise Control system (ACC, a system which reduces the driving burden on the driver. The ACC system primarily supports four driving modes on the road and controls the acceleration and deceleration of the vehicle in order to maintain a set speed or to avoid a crash. This paper proposes more accurate methods of detecting the preceding vehicle by radar while cornering, with consideration for the vehicle sideslip angle, and also of controlling the distance between vehicles. By making full use of the proposed identification logic for preceding vehicles and path estimation logic, an improvement in driving stability was achieved.

  18. Visuomotor Dissociation in Cerebral Scaling of Size

    NARCIS (Netherlands)

    Potgieser, Adriaan R. E.; de Jong, Bauke M.

    2016-01-01

    Estimating size and distance is crucial in effective visuomotor control. The concept of an internal coordinate system implies that visual and motor size parameters are scaled onto a common template. To dissociate perceptual and motor components in such scaling, we performed an fMRI experiment in

  19. Atypical visuomotor performance in children with PDD

    NARCIS (Netherlands)

    Schlooz, W.A.J.M.; Hulstijn, W.

    2012-01-01

    Children with autism spectrum disorders (ASD) frequently encounter difficulties in visuomotor tasks, which are possibly caused by atypical visuoperceptual processing. This was tested in children (aged 9–12 years) with pervasive developmental disorder (PDD; including PDD-NOS and Asperger syndrome),

  20. High-frequency TRNS reduces BOLD activity during visuomotor learning.

    Directory of Open Access Journals (Sweden)

    Catarina Saiote

    Full Text Available Transcranial direct current stimulation (tDCS and transcranial random noise stimulation (tRNS consist in the application of electrical current of small intensity through the scalp, able to modulate perceptual and motor learning, probably by changing brain excitability. We investigated the effects of these transcranial electrical stimulation techniques in the early and later stages of visuomotor learning, as well as associated brain activity changes using functional magnetic resonance imaging (fMRI. We applied anodal and cathodal tDCS, low-frequency and high-frequency tRNS (lf-tRNS, 0.1-100 Hz; hf-tRNS 101-640 Hz, respectively and sham stimulation over the primary motor cortex (M1 during the first 10 minutes of a visuomotor learning paradigm and measured performance changes for 20 minutes after stimulation ceased. Functional imaging scans were acquired throughout the whole experiment. Cathodal tDCS and hf-tRNS showed a tendency to improve and lf-tRNS to hinder early learning during stimulation, an effect that remained for 20 minutes after cessation of stimulation in the late learning phase. Motor learning-related activity decreased in several regions as reported previously, however, there was no significant modulation of brain activity by tDCS. In opposition to this, hf-tRNS was associated with reduced motor task-related-activity bilaterally in the frontal cortex and precuneous, probably due to interaction with ongoing neuronal oscillations. This result highlights the potential of lf-tRNS and hf-tRNS to differentially modulate visuomotor learning and advances our knowledge on neuroplasticity induction approaches combined with functional imaging methods.

  1. Improved neonatal seizure detection using adaptive learning.

    Science.gov (United States)

    Ansari, A H; Cherian, P J; Caicedo, A; De Vos, M; Naulaers, G; Van Huffel, S

    2017-07-01

    In neonatal intensive care units performing continuous EEG monitoring, there is an unmet need for around-the-clock interpretation of EEG, especially for recognizing seizures. In recent years, a few automated seizure detection algorithms have been proposed. However, these are suboptimal in detecting brief-duration seizures (<; 30s), which frequently occur in neonates with severe neurological problems. Recently, a multi-stage neonatal seizure detector, composed of a heuristic and a data-driven classifier was proposed by our group and showed improved detection of brief seizures. In the present work, we propose to add a third stage to the detector in order to use feedback of the Clinical Neurophysiologist and adaptively retune a threshold of the second stage to improve the performance of detection of brief seizures. As a result, the false alarm rate (FAR) of the brief seizure detections decreased by 50% and the positive predictive value (PPV) increased by 18%. At the same time, for all detections, the FAR decreased by 35% and PPV increased by 5% while the good detection rate remained unchanged.

  2. Improvements to the adaptive maneuvering logic program

    Science.gov (United States)

    Burgin, George H.

    1986-01-01

    The Adaptive Maneuvering Logic (AML) computer program simulates close-in, one-on-one air-to-air combat between two fighter aircraft. Three important improvements are described. First, the previously available versions of AML were examined for their suitability as a baseline program. The selected program was then revised to eliminate some programming bugs which were uncovered over the years. A listing of this baseline program is included. Second, the equations governing the motion of the aircraft were completely revised. This resulted in a model with substantially higher fidelity than the original equations of motion provided. It also completely eliminated the over-the-top problem, which occurred in the older versions when the AML-driven aircraft attempted a vertical or near vertical loop. Third, the requirements for a versatile generic, yet realistic, aircraft model were studied and implemented in the program. The report contains detailed tables which make the generic aircraft to be either a modern, high performance aircraft, an older high performance aircraft, or a previous generation jet fighter.

  3. Adaptive Quantum State Tomography Improves Accuracy Quadratically

    Science.gov (United States)

    Mahler, D. H.; Rozema, Lee A.; Darabi, Ardavan; Ferrie, Christopher; Blume-Kohout, Robin; Steinberg, A. M.

    2013-11-01

    We introduce a simple protocol for adaptive quantum state tomography, which reduces the worst-case infidelity [1-F(ρ^,ρ)] between the estimate and the true state from O(1/N) to O(1/N). It uses a single adaptation step and just one extra measurement setting. In a linear optical qubit experiment, we demonstrate a full order of magnitude reduction in infidelity (from 0.1% to 0.01%) for a modest number of samples (N≈3×104).

  4. Improving WCDMA netwotk capacity using adaptive sectorisation ...

    African Journals Online (AJOL)

    A major problem affecting the capacity of Wideband Code Division Multiple Access (WCDMA) is interference. This work focuses on reducing co-channel interference problem by the application of adaptive sectorisation in nonuniform traffic. It considers an isolated areas of congested traffic called Hot Spots (HS).

  5. Chunking during human visuomotor sequence learning.

    Science.gov (United States)

    Sakai, Katsuyuki; Kitaguchi, Katsuya; Hikosaka, Okihide

    2003-09-01

    Motor sequence learning is a process whereby a series of elementary movements is re-coded into an efficient representation for the entire sequence. Here we show that human subjects learn a visuomotor sequence by spontaneously chunking the elementary movements, while each chunk acts as a single memory unit. The subjects learned to press a sequence of 10 sets of two buttons through trial and error. By examining the temporal patterns with which subjects performed a visuomotor sequence, we found that the subjects performed the 10 sets as several clusters of sets, which were separated by long time gaps. While the overall performance time decreased by repeating the same sequence, the clusters became clearer and more consistent. The cluster pattern was uncorrelated with the distance of hand movements and was different across subjects who learned the same sequence. We then split a learned sequence into three segments, while preserving or destroying the clusters in the learned sequence, and shuffled the segments. The performance on the shuffled sequence was more accurate and quicker when the clusters in the original sequence were preserved than when they were destroyed. The results suggest that each cluster is processed as a single memory unit, a chunk, and is necessary for efficient sequence processing. A learned visuomotor sequence is hierarchically represented as chunks that contain several elementary movements. We also found that the temporal patterns of sequence performance transferred from the nondominant to dominant hand, but not vice versa. This may suggest a role of the dominant hemisphere in storage of learned chunks. Together with our previous unit-recording and imaging studies that used the same learning paradigm, we predict specific roles of the dominant parietal area, basal ganglia, and presupplementary motor area in the chunking.

  6. Subtle visuomotor difficulties in preclinical Alzheimer's disease.

    Science.gov (United States)

    Mollica, Maria A; Navarra, Jordi; Fernández-Prieto, Irune; Olives, Jaume; Tort, Adrià; Valech, Natalia; Coll-Padrós, Nina; Molinuevo, José L; Rami, Lorena

    2017-03-01

    Individuals with preclinical Alzheimer's disease (Pre-AD) present nonimpaired cognition, as measured by standard neuropsychological tests. However, detecting subtle difficulties in cognitive functions may be necessary for an early diagnosis and intervention. A new computer-based visuomotor coordination task (VMC) was developed to investigate the possible presence of early visuomotor difficulties in Pre-AD individuals. Associations between VMC task performance and AD biomarkers were studied. The influence of ApoE status on participants' performance was addressed, as well as the relationship between performance and subjective cognitive decline (SCD). Sixty-six cognitively normal (CN) elders (19 Pre-AD and 47 control participants [CTR]) and 15 patients with AD performed the VMC task, which consisted in executing visually guided goal-directed movements that required the coordination of the visual and motor systems. All participants underwent ApoE analysis and lumbar puncture. CN participants also completed an extensive standard neuropsychological battery. Despite presenting normal cognition in standard tests, Pre-AD participants exhibited higher response times (RTs) to complete the VMC task than CTR (p < .01). Besides, patients with AD showed higher RTs than CTR (p < .001) and Pre-AD (p < .05), and more errors than CTR (p < .005). RTs in ApoE4 carriers were higher than that observed in ApoE4 noncarriers (p < .01). In CN individuals, RTs were related to amyloid β-protein 42 (AB42) biomarker (p < .01) and informant-rated SCD (p < .01). The VMC task is able to discriminate Pre-AD from CTR individuals. Moreover, VMC results are associated with AB42 levels in CN individuals, suggesting that visuomotor dysfunction may be a sensitive marker of Pre-AD. © 2015 The British Psychological Society.

  7. An Adaptive Middleware for Improved Computational Performance

    DEFF Research Database (Denmark)

    Bonnichsen, Lars Frydendal

    The performance improvements in computer systems over the past 60 years have been fueled by an exponential increase in energy efficiency. In recent years, the phenomenon known as the end of Dennard’s scaling has slowed energy efficiency improvements — but improving computer energy efficiency...... is more important now than ever. Traditionally, most improvements in computer energy efficiency have come from improvements in lithography — the ability to produce smaller transistors — and computer architecture - the ability to apply those transistors efficiently. Since the end of scaling, we have seen....... In this thesis we champion using software to improve energy efficiency — in particular we develop guidelines for reasoning and evaluating software performance on modern computers, and a middleware that has been designed for modern computers, improving computational performance both in terms of energy...

  8. Adaptive Landing Gear: Optimum Control Strategy and Potential for Improvement

    OpenAIRE

    Grzegorz Mikułowski; Łukasz Jankowski

    2009-01-01

    An adaptive landing gear is a landing gear (LG) capable of active adaptation to particular landing conditions by means of controlled hydraulic force. The objective of the adaptive control is to mitigate the peak force transferred to the aircraft structure during touch-down, and thus to limit the structural fatigue factor. This paper investigates the ultimate limits for improvement due to various strategies of active control. Five strategies are proposed and investigated numerically using a~va...

  9. Adaptive Intelligent Support to Improve Peer Tutoring in Algebra

    Science.gov (United States)

    Walker, Erin; Rummel, Nikol; Koedinger, Kenneth R.

    2014-01-01

    Adaptive collaborative learning support (ACLS) involves collaborative learning environments that adapt their characteristics, and sometimes provide intelligent hints and feedback, to improve individual students' collaborative interactions. ACLS often involves a system that can automatically assess student dialogue, model effective and…

  10. Visuomotor Dissociation in Cerebral Scaling of Size.

    Science.gov (United States)

    Potgieser, Adriaan R E; de Jong, Bauke M

    2016-01-01

    Estimating size and distance is crucial in effective visuomotor control. The concept of an internal coordinate system implies that visual and motor size parameters are scaled onto a common template. To dissociate perceptual and motor components in such scaling, we performed an fMRI experiment in which 16 right-handed subjects copied geometric figures while the result of drawing remained out of sight. Either the size of the example figure varied while maintaining a constant size of drawing (visual incongruity) or the size of the examples remained constant while subjects were instructed to make changes in size (motor incongruity). These incongruent were compared to congruent conditions. Statistical Parametric Mapping (SPM8) revealed brain activations related to size incongruity in the dorsolateral prefrontal and inferior parietal cortex, pre-SMA / anterior cingulate and anterior insula, dominant in the right hemisphere. This pattern represented simultaneous use of a 'resized' virtual template and actual picture information requiring spatial working memory, early-stage attention shifting and inhibitory control. Activations were strongest in motor incongruity while right pre-dorsal premotor activation specifically occurred in this condition. Visual incongruity additionally relied on a ventral visual pathway. Left ventral premotor activation occurred in all variably sized drawing while constant visuomotor size, compared to congruent size variation, uniquely activated the lateral occipital cortex additional to superior parietal regions. These results highlight size as a fundamental parameter in both general hand movement and movement guided by objects perceived in the context of surrounding 3D space.

  11. Visuomotor Dissociation in Cerebral Scaling of Size

    Science.gov (United States)

    Potgieser, Adriaan R. E.; de Jong, Bauke M.

    2016-01-01

    Estimating size and distance is crucial in effective visuomotor control. The concept of an internal coordinate system implies that visual and motor size parameters are scaled onto a common template. To dissociate perceptual and motor components in such scaling, we performed an fMRI experiment in which 16 right-handed subjects copied geometric figures while the result of drawing remained out of sight. Either the size of the example figure varied while maintaining a constant size of drawing (visual incongruity) or the size of the examples remained constant while subjects were instructed to make changes in size (motor incongruity). These incongruent were compared to congruent conditions. Statistical Parametric Mapping (SPM8) revealed brain activations related to size incongruity in the dorsolateral prefrontal and inferior parietal cortex, pre-SMA / anterior cingulate and anterior insula, dominant in the right hemisphere. This pattern represented simultaneous use of a ‘resized’ virtual template and actual picture information requiring spatial working memory, early-stage attention shifting and inhibitory control. Activations were strongest in motor incongruity while right pre-dorsal premotor activation specifically occurred in this condition. Visual incongruity additionally relied on a ventral visual pathway. Left ventral premotor activation occurred in all variably sized drawing while constant visuomotor size, compared to congruent size variation, uniquely activated the lateral occipital cortex additional to superior parietal regions. These results highlight size as a fundamental parameter in both general hand movement and movement guided by objects perceived in the context of surrounding 3D space. PMID:26963705

  12. Visuomotor Dissociation in Cerebral Scaling of Size.

    Directory of Open Access Journals (Sweden)

    Adriaan R E Potgieser

    Full Text Available Estimating size and distance is crucial in effective visuomotor control. The concept of an internal coordinate system implies that visual and motor size parameters are scaled onto a common template. To dissociate perceptual and motor components in such scaling, we performed an fMRI experiment in which 16 right-handed subjects copied geometric figures while the result of drawing remained out of sight. Either the size of the example figure varied while maintaining a constant size of drawing (visual incongruity or the size of the examples remained constant while subjects were instructed to make changes in size (motor incongruity. These incongruent were compared to congruent conditions. Statistical Parametric Mapping (SPM8 revealed brain activations related to size incongruity in the dorsolateral prefrontal and inferior parietal cortex, pre-SMA / anterior cingulate and anterior insula, dominant in the right hemisphere. This pattern represented simultaneous use of a 'resized' virtual template and actual picture information requiring spatial working memory, early-stage attention shifting and inhibitory control. Activations were strongest in motor incongruity while right pre-dorsal premotor activation specifically occurred in this condition. Visual incongruity additionally relied on a ventral visual pathway. Left ventral premotor activation occurred in all variably sized drawing while constant visuomotor size, compared to congruent size variation, uniquely activated the lateral occipital cortex additional to superior parietal regions. These results highlight size as a fundamental parameter in both general hand movement and movement guided by objects perceived in the context of surrounding 3D space.

  13. Modular inverse reinforcement learning for visuomotor behavior.

    Science.gov (United States)

    Rothkopf, Constantin A; Ballard, Dana H

    2013-08-01

    In a large variety of situations one would like to have an expressive and accurate model of observed animal or human behavior. While general purpose mathematical models may capture successfully properties of observed behavior, it is desirable to root models in biological facts. Because of ample empirical evidence for reward-based learning in visuomotor tasks, we use a computational model based on the assumption that the observed agent is balancing the costs and benefits of its behavior to meet its goals. This leads to using the framework of reinforcement learning, which additionally provides well-established algorithms for learning of visuomotor task solutions. To quantify the agent's goals as rewards implicit in the observed behavior, we propose to use inverse reinforcement learning, which quantifies the agent's goals as rewards implicit in the observed behavior. Based on the assumption of a modular cognitive architecture, we introduce a modular inverse reinforcement learning algorithm that estimates the relative reward contributions of the component tasks in navigation, consisting of following a path while avoiding obstacles and approaching targets. It is shown how to recover the component reward weights for individual tasks and that variability in observed trajectories can be explained succinctly through behavioral goals. It is demonstrated through simulations that good estimates can be obtained already with modest amounts of observation data, which in turn allows the prediction of behavior in novel configurations.

  14. Adaptive Filtering Queueing for Improving Fairness

    Directory of Open Access Journals (Sweden)

    Jui-Pin Yang

    2015-06-01

    Full Text Available In this paper, we propose a scalable and efficient Active Queue Management (AQM scheme to provide fair bandwidth sharing when traffic is congested dubbed Adaptive Filtering Queueing (AFQ. First, AFQ identifies the filtering level of an arriving packet by comparing it with a flow label selected at random from the first level to an estimated level in the filtering level table. Based on the accepted traffic estimation and the previous fair filtering level, AFQ updates the fair filtering level. Next, AFQ uses a simple packet-dropping algorithm to determine whether arriving packets are accepted or discarded. To enhance AFQ’s feasibility in high-speed networks, we propose a two-layer mapping mechanism to effectively simplify the packet comparison operations. Simulation results demonstrate that AFQ achieves optimal fairness when compared with Rotating Preference Queues (RPQ, Core-Stateless Fair Queueing (CSFQ, CHOose and Keep for responsive flows, CHOose and Kill for unresponsive flows (CHOKe and First-In First-Out (FIFO schemes under a variety of traffic conditions.

  15. Quality circles: Organizational adaptations, improvements and results

    Science.gov (United States)

    Tortorich, R.

    1985-01-01

    The effective application in industry and government of quality circles work was demonstrated. The results achieved in quality and productivity improvements and cost savings are impressive. The circle process should be institutionalized within industry and government. The stages of circle program growth, innovations that help achieve circle process institutionalization, and the result achieved at Martin Marietta's Michoud Division and within the National Aeronautics and Space Administration (NASA) are addressed.

  16. Is effect of transcranial direct current stimulation on visuomotor coordination dependent on task difficulty?

    Directory of Open Access Journals (Sweden)

    Yong Hyun Kwon

    2015-01-01

    Full Text Available Transcranial direct current stimulation (tDCS, an emerging technique for non-invasive brain stimulation, is increasingly used to induce changes in cortical excitability and modulate motor behavior, especially for upper limbs. The purpose of this study was to investigate the effects of tDCS of the primary motor cortex on visuomotor coordination based on three levels of task difficulty in healthy subjects. Thirty-eight healthy participants underwent real tDCS or sham tDCS. Using a single-blind, sham-controlled crossover design, tDCS was applied to the primary motor cortex. For real tDCS conditions, tDCS intensity was 1 mA while stimulation was applied for 15 minutes. For the sham tDCS, electrodes were placed in the same position, but the stimulator was turned off after 5 seconds. Visuomotor tracking task, consisting of three levels (levels 1, 2, 3 of difficulty with higher level indicating greater difficulty, was performed before and after tDCS application. At level 2, real tDCS of the primary motor cortex improved the accurate index compared to the sham tDCS. However, at levels 1 and 3, the accurate index was not significantly increased after real tDCS compared to the sham tDCS. These findings suggest that tasks of moderate difficulty may improve visuomotor coordination in healthy subjects when tDCS is applied compared with easier or more difficult tasks.

  17. Neural Correlates of Expert Visuomotor Performance in Badminton Players.

    Science.gov (United States)

    Hülsdünker, Thorben; Strüder, Heiko K; Mierau, Andreas

    2016-11-01

    Elite/skilled athletes participating in sports that require the initiation of targeted movements in response to visual cues under critical time pressure typically outperform nonathletes in a visuomotor reaction task. However, the exact physiological mechanisms of this advantage remain unclear. Therefore, this study aimed to determine the neurophysiological processes contributing to superior visuomotor performance in athletes using visual evoked potential (VEP). Central and peripheral determinants of visuomotor reaction time were investigated in 15 skilled badminton players and 28 age-matched nonathletic controls. To determine the speed of visual signal perception in the cortex, chromatic and achromatic pattern reversal stimuli were presented, and VEP values were recorded with a 64-channel EEG system. Further, a simple visuomotor reaction task was performed to investigate the transformation of the visual into a motor signal in the brain as well as the timing of muscular activation. Amplitude and latency of VEP (N75, P100, and N145) revealed that the athletes did not significantly differ from the nonathletes. However, visuomotor reaction time was significantly reduced in the athletes compared with nonathletes (athletes = 234.9 ms, nonathletes = 260.3 ms, P = 0.015). This was accompanied by an earlier activation of the premotor and supplementary motor areas (athletes = 163.9 ms, nonathletes = 199.1 ms, P = 0.015) as well as an earlier EMG onset (athletes = 167.5 ms, nonathletes = 206.5 ms, P < 0.001). The latency of premotor and supplementary motor area activation was correlated with EMG onset (r = 0.41) and visuomotor reaction time (r = 0.43). The results of this study indicate that superior visuomotor performance in athletes originates from faster visuomotor transformation in the premotor and supplementary motor cortical regions rather than from earlier perception of visual signals in the visual cortex.

  18. Developing a new experimental system for an undergraduate laboratory exercise to teach theories of visuomotor learning.

    Science.gov (United States)

    Kasuga, Shoko; Ushiba, Junichi

    2014-01-01

    Humans have a flexible motor ability to adapt their movements to changes in the internal/external environment. For example, using arm-reaching tasks, a number of studies experimentally showed that participants adapt to a novel visuomotor environment. These results helped develop computational models of motor learning implemented in the central nervous system. Despite the importance of such experimental paradigms for exploring the mechanisms of motor learning, because of the cost and preparation time, most students are unable to participate in such experiments. Therefore, in the current study, to help students better understand motor learning theories, we developed a simple finger-reaching experimental system using commonly used laptop PC components with an open-source programming language (Processing Motor Learning Toolkit: PMLT). We found that compared to a commercially available robotic arm-reaching device, our PMLT accomplished similar learning goals (difference in the error reduction between the devices, P = 0.10). In addition, consistent with previous reports from visuomotor learning studies, the participants showed after-effects indicating an adaptation of the motor learning system. The results suggest that PMLT can serve as a new experimental system for an undergraduate laboratory exercise of motor learning theories with minimal time and cost for instructors.

  19. Adaptive Landing Gear: Optimum Control Strategy and Potential for Improvement

    Directory of Open Access Journals (Sweden)

    Grzegorz Mikułowski

    2009-01-01

    Full Text Available An adaptive landing gear is a landing gear (LG capable of active adaptation to particular landing conditions by means of controlled hydraulic force. The objective of the adaptive control is to mitigate the peak force transferred to the aircraft structure during touch-down, and thus to limit the structural fatigue factor. This paper investigates the ultimate limits for improvement due to various strategies of active control. Five strategies are proposed and investigated numerically using a~validated model of a real, passive landing gear as a reference. Potential for improvement is estimated statistically in terms of the mean and median (significant peak strut forces as well as in terms of the extended safe sinking velocity range. Three control strategies are verified experimentally using a laboratory test stand.

  20. Reversing motor adaptation deficits in the ageing brain using non-invasive stimulation.

    Science.gov (United States)

    Panouillères, Muriel T N; Joundi, Raed A; Brittain, John-Stuart; Jenkinson, Ned

    2015-08-15

    Healthy ageing in man is associated with a decline in motor adaptation. Transcranial direct current stimulation (TDCS) over the primary motor cortex (M1) or the lateral cerebellum can improve motor adaptation in young and older adults, but as yet no direct comparisons of TDCS effects exist between the two age groups and the two stimulation sites. TDCS over M1 enhanced the motor adaptation in both age groups by ∼30% relative to their respective non-stimulated groups and improved the performance of older adults to the extent that it compared with that of young adults without stimulation. The study suggests that the plastic mechanisms activated by TDCS that underpin improvements in motor behaviour in young adults remain available in older adults. The results indicate that TDCS may be a useful tool to help combat the normal decline in motor performance seen in normal healthy ageing. Healthy ageing is characterised by deterioration of motor performance. In normal circumstances motor adaptation corrects for movements' inaccuracies and as such, it is critical in maintaining optimal motor control. However, motor adaptation performance is also known to decline with age. Anodal transcranial direct current stimulation (TDCS) of the cerebellum and the primary motor cortex (M1) have been found to improve visuomotor adaptation in healthy young and older adults. However, no study has directly compared the effect of TDCS on motor adaptation between the two age populations. The aim of our study was to investigate whether the application of anodal TDCS over the lateral cerebellum and M1 affected motor adaptation in young and older adults similarly. Young and older participants performed a visuomotor rotation task and concurrently received TDCS over the left M1, the right cerebellum or received sham stimulation. Our results replicated the finding that older adults are impaired compared to the young adults in visuomotor adaptation. At the end of the adaptation session, older adults

  1. Eye-hand coordination during dynamic visuomotor rotations.

    Directory of Open Access Journals (Sweden)

    Lorenzo Masia

    Full Text Available BACKGROUND: for many technology-driven visuomotor tasks such as tele-surgery, human operators face situations in which the frames of reference for vision and action are misaligned and need to be compensated in order to perform the tasks with the necessary precision. The cognitive mechanisms for the selection of appropriate frames of reference are still not fully understood. This study investigated the effect of changing visual and kinesthetic frames of reference during wrist pointing, simulating activities typical for tele-operations. METHODS: using a robotic manipulandum, subjects had to perform center-out pointing movements to visual targets presented on a computer screen, by coordinating wrist flexion/extension with abduction/adduction. We compared movements in which the frames of reference were aligned (unperturbed condition with movements performed under different combinations of visual/kinesthetic dynamic perturbations. The visual frame of reference was centered to the computer screen, while the kinesthetic frame was centered around the wrist joint. Both frames changed their orientation dynamically (angular velocity = 36 degrees /s with respect to the head-centered frame of reference (the eyes. Perturbations were either unimodal (visual or kinesthetic, or bimodal (visual+kinesthetic. As expected, pointing performance was best in the unperturbed condition. The spatial pointing error dramatically worsened during both unimodal and most bimodal conditions. However, in the bimodal condition, in which both disturbances were in phase, adaptation was very fast and kinematic performance indicators approached the values of the unperturbed condition. CONCLUSIONS: this result suggests that subjects learned to exploit an "affordance" made available by the invariant phase relation between the visual and kinesthetic frames. It seems that after detecting such invariance, subjects used the kinesthetic input as an informative signal rather than a

  2. Improving Water Governance and Climate Change Adaptation in ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Improving Water Governance and Climate Change Adaptation in Cambodia. Cambodia's Tonle Sap Lake is the largest freshwater lake in Southeast Asia. It is estimated that up to half of Cambodia's population benefits directly or indirectly from the lake's resources. Over the next few decades, climate change and new ...

  3. Possible routes to improve adaptive management of firms

    NARCIS (Netherlands)

    Stuiver, M.; Westerink, J.

    2016-01-01

    This study explores possible routes to improve the adaptive management of firms and proposes to view firms as social-ecological systems. We conceptualise three possible ways in which firms can frame their relation with the natural environment. The first is impact related: strategies for assessing

  4. Flooding in Dakar suburbs: towards adaptation by improving ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Flooding in Dakar suburbs: towards adaptation by improving buildings, infrastructure and local governance. Managing flooding is one of the major challenges Africa faces in regard to climate change. Frantic urbanization, out of control urban sprawl and destitute populations forced to live on marginal land have led to ...

  5. Barley adaptation and improvement in the Mediterranean basin

    NARCIS (Netherlands)

    Pswarayi, A.; Eeuwijk, van F.A.; Ceccarelli, S.; Grando, S.; Comadran, J.; Russell, J.R.; Stanca, A.M.; Francia, E.; Pecchioni, N.; Akar, T.; Al-Yassin, A.; Benbelkacem, A.; Choumane, W.; Karrou, M.; Ouabbou, H.; Bort, J.; Araus, J.L.; Molina-Cano, J.L.; Thomas, W.T.B.; Romagosa, I.

    2008-01-01

    To study barley adaptation and improvement in the Mediterranean basin, a collection of 188 entries comprising landraces and old genotypes and current modern varieties from the Mediterranean basin and elsewhere was tested on moisture-contrasted environments in seven Mediterranean countries, during

  6. Adaptive optics simulation performance improvements using reconfigurable logic.

    Science.gov (United States)

    Basden, Alastair

    2007-02-20

    A technique used to accelerate an adaptive optics simulation platform using reconfigurable logic is described. The performance of parts of this simulation has been improved by up to 600 times (reducing computation times by this factor) by implementing algorithms within hardware and enables adaptive optics simulations to be carried out in a reasonable time scale. This demonstrates that it is possible to use reconfigurable logic to accelerate computational codes by very large factors when compared with conventional software approaches, and this has relevance for many computationally intensive applications. The use of reconfigurable logic for high performance computing is currently in its infancy and has never before been applied to this field.

  7. Adaptive Programming Improves Outcomes in Drug Court: An Experimental Trial.

    Science.gov (United States)

    Marlowe, Douglas B; Festinger, David S; Dugosh, Karen L; Benasutti, Kathleen M; Fox, Gloria; Croft, Jason R

    2012-04-01

    Prior studies in Drug Courts reported improved outcomes when participants were matched to schedules of judicial status hearings based on their criminological risk level. The current experiment determined whether incremental efficacy could be gained by periodically adjusting the schedule of status hearings and clinical case-management sessions in response to participants' ensuing performance in the program. The adjustments were made pursuant to a priori criteria specified in an adaptive algorithm. Results confirmed that participants in the full adaptive condition (n = 62) were more than twice as likely as those assigned to baseline-matching only (n = 63) to be drug-abstinent during the first 18 weeks of the program; however, graduation rates and the average time to case resolution were not significantly different. The positive effects of the adaptive program appear to have stemmed from holding noncompliant participants more accountable for meeting their attendance obligations in the program. Directions for future research and practice implications are discussed.

  8. Improving cellulase production by Aspergillus niger using adaptive evolution.

    Science.gov (United States)

    Patyshakuliyeva, Aleksandrina; Arentshorst, Mark; Allijn, Iris E; Ram, Arthur F J; de Vries, Ronald P; Gelber, Isabelle Benoit

    2016-06-01

    To evaluate the potential of adaptive evolution as a tool in generating strains with an improved production of plant biomass degrading enzymes. An Aspergillus niger cellulase mutant was obtained by adaptive evolution. Physiological properties of this mutant revealed a five times higher cellulose production than the parental strain. Transcriptomic analysis revealed that the expression of noxR, encoding the regulatory subunit of the NADPH oxidase complex, was reduced in the mutant compared to the parental strain. Subsequent analysis of a noxR knockout strain showed the same phenotypic effect as observed for the evolution mutant, confirming the role of NoxR in cellulose degradation. Adaptive evolution is an efficient approach to modify a strain and activate genes involved in polysaccharide degradation.

  9. Cross-Adaptation: Heat and Cold Adaptation to Improve Physiological and Cellular Responses to Hypoxia.

    Science.gov (United States)

    Gibson, Oliver R; Taylor, Lee; Watt, Peter W; Maxwell, Neil S

    2017-09-01

    To prepare for extremes of heat, cold or low partial pressures of oxygen (O 2 ), humans can undertake a period of acclimation or acclimatization to induce environment-specific adaptations, e.g. heat acclimation (HA), cold acclimation (CA), or altitude training. While these strategies are effective, they are not always feasible due to logistical impracticalities. Cross-adaptation is a term used to describe the phenomenon whereby alternative environmental interventions, e.g. HA or CA, may be a beneficial alternative to altitude interventions, providing physiological stress and inducing adaptations observable at altitude. HA can attenuate physiological strain at rest and during moderate-intensity exercise at altitude via adaptations allied to improved O 2 delivery to metabolically active tissue, likely following increases in plasma volume and reductions in body temperature. CA appears to improve physiological responses to altitude by attenuating the autonomic response to altitude. While no cross-acclimation-derived exercise performance/capacity data have been measured following CA, post-HA improvements in performance underpinned by aerobic metabolism, and therefore dependent on O 2 delivery at altitude, are likely. At a cellular level, heat shock protein responses to altitude are attenuated by prior HA, suggesting that an attenuation of the cellular stress response and therefore a reduced disruption to homeostasis at altitude has occurred. This process is known as cross-tolerance. The effects of CA on markers of cross-tolerance is an area requiring further investigation. Because much of the evidence relating to cross-adaptation to altitude has examined the benefits at moderate to high altitudes, future research examining responses at lower altitudes should be conducted, given that these environments are more frequently visited by athletes and workers. Mechanistic work to identify the specific physiological and cellular pathways responsible for cross-adaptation between

  10. Virtual hand illusion induced by visuomotor correlations.

    Science.gov (United States)

    Sanchez-Vives, Maria V; Spanlang, Bernhard; Frisoli, Antonio; Bergamasco, Massimo; Slater, Mel

    2010-04-29

    Our body schema gives the subjective impression of being highly stable. However, a number of easily-evoked illusions illustrate its remarkable malleability. In the rubber-hand illusion, illusory ownership of a rubber-hand is evoked by synchronous visual and tactile stimulation on a visible rubber arm and on the hidden real arm. Ownership is concurrent with a proprioceptive illusion of displacement of the arm position towards the fake arm. We have previously shown that this illusion of ownership plus the proprioceptive displacement also occurs towards a virtual 3D projection of an arm when the appropriate synchronous visuotactile stimulation is provided. Our objective here was to explore whether these illusions (ownership and proprioceptive displacement) can be induced by only synchronous visuomotor stimulation, in the absence of tactile stimulation. To achieve this we used a data-glove that uses sensors transmitting the positions of fingers to a virtually projected hand in the synchronous but not in the asynchronous condition. The illusion of ownership was measured by means of questionnaires. Questions related to ownership gave significantly larger values for the synchronous than for the asynchronous condition. Proprioceptive displacement provided an objective measure of the illusion and had a median value of 3.5 cm difference between the synchronous and asynchronous conditions. In addition, the correlation between the feeling of ownership of the virtual arm and the size of the drift was significant. We conclude that synchrony between visual and proprioceptive information along with motor activity is able to induce an illusion of ownership over a virtual arm. This has implications regarding the brain mechanisms underlying body ownership as well as the use of virtual bodies in therapies and rehabilitation.

  11. Virtual hand illusion induced by visuomotor correlations.

    Directory of Open Access Journals (Sweden)

    Maria V Sanchez-Vives

    Full Text Available BACKGROUND: Our body schema gives the subjective impression of being highly stable. However, a number of easily-evoked illusions illustrate its remarkable malleability. In the rubber-hand illusion, illusory ownership of a rubber-hand is evoked by synchronous visual and tactile stimulation on a visible rubber arm and on the hidden real arm. Ownership is concurrent with a proprioceptive illusion of displacement of the arm position towards the fake arm. We have previously shown that this illusion of ownership plus the proprioceptive displacement also occurs towards a virtual 3D projection of an arm when the appropriate synchronous visuotactile stimulation is provided. Our objective here was to explore whether these illusions (ownership and proprioceptive displacement can be induced by only synchronous visuomotor stimulation, in the absence of tactile stimulation. METHODOLOGY/PRINCIPAL FINDINGS: To achieve this we used a data-glove that uses sensors transmitting the positions of fingers to a virtually projected hand in the synchronous but not in the asynchronous condition. The illusion of ownership was measured by means of questionnaires. Questions related to ownership gave significantly larger values for the synchronous than for the asynchronous condition. Proprioceptive displacement provided an objective measure of the illusion and had a median value of 3.5 cm difference between the synchronous and asynchronous conditions. In addition, the correlation between the feeling of ownership of the virtual arm and the size of the drift was significant. CONCLUSIONS/SIGNIFICANCE: We conclude that synchrony between visual and proprioceptive information along with motor activity is able to induce an illusion of ownership over a virtual arm. This has implications regarding the brain mechanisms underlying body ownership as well as the use of virtual bodies in therapies and rehabilitation.

  12. GESTALT GAME TO IMPROVE STUDENTS’ ADAPTABILITY IN PONDOK PESANTREN

    OpenAIRE

    Imas Kania Rahman; Furqon Furqon

    2011-01-01

    This study aims at finding the effectiveness of guidance and counselling through Gestalt Game technique in improving students’ adaptability in two Islamic boarding schools. The study was conducted by using a pretest-posttest nonequivalent group design involving four groups of students from two different Islamic boarding schools. The study considered the influnce of gender and boarding school environment towards the effectiveness of Gestalt Game. It was conducted by controlling ...

  13. Sensorimotor Adaptability Training Improves Motor and Dual-Task Performance

    Science.gov (United States)

    Bloomberg, J.J.; Peters, B.T.; Mulavara, A.P.; Brady, R.; Batson, C.; Cohen, H.S.

    2009-01-01

    The overall objective of our project is to develop a sensorimotor adaptability (SA) training program designed to facilitate recovery of functional capabilities when astronauts transition to different gravitational environments. The goal of our current study was to determine if SA training using variation in visual flow and support surface motion produces improved performance in a novel sensory environment and demonstrate the retention characteristics of SA training.

  14. Assessment and Training of Visuomotor Reaction Time for Football Injury Prevention.

    Science.gov (United States)

    Wilkerson, Gary B; Simpson, Kevin A; Clark, Ryan A

    2017-01-01

    Neurocognitive reaction time has been associated with musculoskeletal injury risk, but visuomotor reaction time (VMRT) derived from tests that present greater challenges to visual stimulus detection and motor response execution may have a stronger association. To assess VMRT as a predictor of injury and the extent to which improvement may result from VMRT training. Cohort study. University athletic performance center. 76 National Collegiate Athletic Association Division-I FCS football players (19.5 ± 1.4 y, 1.85 ± 0.06 m, 102.98 ± 19.06 kg). Preparticipation and postseason assessments. A subset of players who exhibited slowest VMRT in relation to the cohort's postseason median value participated in a 6-wk training program. Injury occurrence was related to preparticipation VMRT, which was represented by both number of target hits in 60 s and average elapsed time between hits (ms). Receiver operating characteristic analysis identified the optimum cut point for a binary injury risk classification. A nonparametric repeated-measures analysis of ranks procedure was used to compare posttraining VMRT values for slow players who completed at least half of the training sessions (n = 15) with those for untrained fast players (n = 27). A preparticipation cut point of ≤85 hits (≥705 ms) discriminated injured from noninjured players with odds ratio = 2.30 (90% confidence interval, 1.05-5.06). Slow players who completed the training exhibited significant improvement in visuomotor performance compared with baseline (standardized response mean = 2.53), whereas untrained players exhibited a small performance decrement (group × trial interaction effect, L2 = 28.74; P injury risk factor for college football players. More research is needed to refine visuomotor reaction-time screening and training methods and to determine the extent to which improved performance values can reduce injury incidence.

  15. Visual feedback alters force control and functional activity in the visuomotor network after stroke

    Directory of Open Access Journals (Sweden)

    Derek B. Archer

    2018-01-01

    Full Text Available Modulating visual feedback may be a viable option to improve motor function after stroke, but the neurophysiological basis for this improvement is not clear. Visual gain can be manipulated by increasing or decreasing the spatial amplitude of an error signal. Here, we combined a unilateral visually guided grip force task with functional MRI to understand how changes in the gain of visual feedback alter brain activity in the chronic phase after stroke. Analyses focused on brain activation when force was produced by the most impaired hand of the stroke group as compared to the non-dominant hand of the control group. Our experiment produced three novel results. First, gain-related improvements in force control were associated with an increase in activity in many regions within the visuomotor network in both the stroke and control groups. These regions include the extrastriate visual cortex, inferior parietal lobule, ventral premotor cortex, cerebellum, and supplementary motor area. Second, the stroke group showed gain-related increases in activity in additional regions of lobules VI and VIIb of the ipsilateral cerebellum. Third, relative to the control group, the stroke group showed increased activity in the ipsilateral primary motor cortex, and activity in this region did not vary as a function of visual feedback gain. The visuomotor network, cerebellum, and ipsilateral primary motor cortex have each been targeted in rehabilitation interventions after stroke. Our observations provide new insight into the role these regions play in processing visual gain during a precisely controlled visuomotor task in the chronic phase after stroke.

  16. Improved Adaptive LSB Steganography Based on Chaos and Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Yu Lifang

    2010-01-01

    Full Text Available We propose a novel steganographic method in JPEG images with high performance. Firstly, we propose improved adaptive LSB steganography, which can achieve high capacity while preserving the first-order statistics. Secondly, in order to minimize visual degradation of the stego image, we shuffle bits-order of the message based on chaos whose parameters are selected by the genetic algorithm. Shuffling message's bits-order provides us with a new way to improve the performance of steganography. Experimental results show that our method outperforms classical steganographic methods in image quality, while preserving characteristics of histogram and providing high capacity.

  17. Improved Adaptive Routing Algorithm in Distributed Data Centers

    Directory of Open Access Journals (Sweden)

    Dmitry Perepelkin

    2017-01-01

    Full Text Available Currently, telecom operators use virtualization of network infrastructure based on Data Centers (DCs. But when a company grows to a certain size and one DC is not sufficient, there are questions how to further develop the network infrastructure. There is a need to expand existing DC boundaries or to add new elements in the network structure. In this paper, we propose improved adaptive routing algorithm in distributed networks of DCs with united service providers, which increases the efficiency of adaptive routing process during dynamic adding of nodes or communication links. The mathematical model and enlarged form of algorithm are shown in the work. In the paper, a comparison of the proposed algorithm with known analogies, such as modified Dijkstra's algorithm and paired transitions algorithm, is performed. To validate the correctness of proposed algorithm, we developed software for simulation of adaptive routing processes in networks of distributed DCs. Comparative analysis of adaptive routing algorithms in distributed networks of DCs with united service providers confirms the effectiveness of the proposed approach and reduces the complexity of constructing routing tables to the value O(mN.

  18. Auditory-perceptual learning improves speech motor adaptation in children.

    Science.gov (United States)

    Shiller, Douglas M; Rochon, Marie-Lyne

    2014-08-01

    Auditory feedback plays an important role in children's speech development by providing the child with information about speech outcomes that is used to learn and fine-tune speech motor plans. The use of auditory feedback in speech motor learning has been extensively studied in adults by examining oral motor responses to manipulations of auditory feedback during speech production. Children are also capable of adapting speech motor patterns to perceived changes in auditory feedback; however, it is not known whether their capacity for motor learning is limited by immature auditory-perceptual abilities. Here, the link between speech perceptual ability and the capacity for motor learning was explored in two groups of 5- to 7-year-old children who underwent a period of auditory perceptual training followed by tests of speech motor adaptation to altered auditory feedback. One group received perceptual training on a speech acoustic property relevant to the motor task while a control group received perceptual training on an irrelevant speech contrast. Learned perceptual improvements led to an enhancement in speech motor adaptation (proportional to the perceptual change) only for the experimental group. The results indicate that children's ability to perceive relevant speech acoustic properties has a direct influence on their capacity for sensory-based speech motor adaptation.

  19. Auditory-Perceptual Learning Improves Speech Motor Adaptation in Children

    Science.gov (United States)

    Shiller, Douglas M.; Rochon, Marie-Lyne

    2015-01-01

    Auditory feedback plays an important role in children’s speech development by providing the child with information about speech outcomes that is used to learn and fine-tune speech motor plans. The use of auditory feedback in speech motor learning has been extensively studied in adults by examining oral motor responses to manipulations of auditory feedback during speech production. Children are also capable of adapting speech motor patterns to perceived changes in auditory feedback, however it is not known whether their capacity for motor learning is limited by immature auditory-perceptual abilities. Here, the link between speech perceptual ability and the capacity for motor learning was explored in two groups of 5–7-year-old children who underwent a period of auditory perceptual training followed by tests of speech motor adaptation to altered auditory feedback. One group received perceptual training on a speech acoustic property relevant to the motor task while a control group received perceptual training on an irrelevant speech contrast. Learned perceptual improvements led to an enhancement in speech motor adaptation (proportional to the perceptual change) only for the experimental group. The results indicate that children’s ability to perceive relevant speech acoustic properties has a direct influence on their capacity for sensory-based speech motor adaptation. PMID:24842067

  20. Adaptive whitening of the electromyogram to improve amplitude estimation.

    Science.gov (United States)

    Clancy, E A; Farry, K A

    2000-06-01

    Previous research showed that whitening the surface electromyogram (EMG) can improve EMG amplitude estimation (where EMG amplitude is defined as the time-varying standard deviation of the EMG). However, conventional whitening via a linear filter seems to fail at low EMG amplitude levels, perhaps due to additive background noise in the measured EMG. This paper describes an adaptive whitening technique that overcomes this problem by cascading a nonadaptive whitening filter, an adaptive Wiener filter, and an adaptive gain correction. These stages can be calibrated from two, five second duration, constant-angle, constant-force contractions, one at a reference level [e.g., 50% maximum voluntary contraction (MVC)] and one at 0% MVC. In experimental studies, subjects used real-time EMG amplitude estimates to track a uniform-density, band-limited random target. With a 0.25-Hz bandwidth target, either adaptive whitening or multiple-channel processing reduced the tracking error roughly half-way to the error achieved using the dynamometer signal as the feedback. At the 1.00-Hz bandwidth, all of the EMG processors had errors equivalent to that of the dynamometer signal, reflecting that errors in this task were dominated by subjects' inability to track targets at this bandwidth. Increases in the additive noise level, smoothing window length, and tracking bandwidth diminish the advantages of whitening.

  1. To lead and to lag - forward and backward recalibration of perceived visuo-motor simultaneity

    Directory of Open Access Journals (Sweden)

    Marieke eRohde

    2013-01-01

    Full Text Available Studies on human recalibration of perceived visuo-motor simultaneity so far have been limited to the study of recalibration to movement-lead temporal discrepancies (visual lags. We studied adaptation to both vision-lead and movement-lead discrepancies, to test for differences between these conditions, as a leading visual stimulus violates the underlying cause-effect structure. To this end, we manipulated the temporal relationship between a motor action (button press and a visual event (flashed disk in a training phase. Participants were tested in a temporal order judgment task and perceived simultaneity (PSS was compared before and after recalibration. A PHANToM© force-feedback device that tracks the finger position in real time was used to display a virtual button. We predicted the timing of full compression of the button from early movement onset in order to time visual stimuli even before the movement event of the full button press. The results show that recalibration of perceived visuo-motor simultaneity is evident in both directions and does not differ in magnitude between the conditions. The strength of recalibration decreases with perceptual accuracy, suggesting the possibility that some participants recalibrate less because they detect the discrepancy. We conclude that the mechanisms of temporal recalibration work in both direction and there is no evidence that they are asymmetrical around the point of actual simultaneity, despite the underlying asymmetry in the cause-effect relation.

  2. Moving to Capture Children's Attention: Developing a Methodology for Measuring Visuomotor Attention.

    Directory of Open Access Journals (Sweden)

    Liam J B Hill

    Full Text Available Attention underpins many activities integral to a child's development. However, methodological limitations currently make large-scale assessment of children's attentional skill impractical, costly and lacking in ecological validity. Consequently we developed a measure of 'Visual Motor Attention' (VMA-a construct defined as the ability to sustain and adapt visuomotor behaviour in response to task-relevant visual information. In a series of experiments, we evaluated the capability of our method to measure attentional processes and their contributions in guiding visuomotor behaviour. Experiment 1 established the method's core features (ability to track stimuli moving on a tablet-computer screen with a hand-held stylus and demonstrated its sensitivity to principled manipulations in adults' attentional load. Experiment 2 standardised a format suitable for use with children and showed construct validity by capturing developmental changes in executive attention processes. Experiment 3 tested the hypothesis that children with and without coordination difficulties would show qualitatively different response patterns, finding an interaction between the cognitive and motor factors underpinning responses. Experiment 4 identified associations between VMA performance and existing standardised attention assessments and thereby confirmed convergent validity. These results establish a novel approach to measuring childhood attention that can produce meaningful functional assessments that capture how attention operates in an ecologically valid context (i.e. attention's specific contribution to visuomanual action.

  3. Exploration and Exploitation in Visuomotor Prediction of Autonomous Agents

    NARCIS (Netherlands)

    Bliek, L.

    2013-01-01

    This paper discusses various techniques to let an agent learn how to predict the effects of its own actions on its sensor data autonomously, and their usefulness to apply them to visual sensors. An Extreme Learning Machine is used for visuomotor prediction, while various autonomous control

  4. Exploring Visuomotor Priming Following Biological and Non-Biological Stimuli

    Science.gov (United States)

    Gowen, E.; Bradshaw, C.; Galpin, A.; Lawrence, A.; Poliakoff, E.

    2010-01-01

    Observation of human actions influences the observer's own motor system, termed visuomotor priming, and is believed to be caused by automatic activation of mirror neurons. Evidence suggests that priming effects are larger for biological (human) as opposed to non-biological (object) stimuli and enhanced when viewing stimuli in mirror compared to…

  5. Handwriting, visuomotor integration, and neurological condition at school age

    NARCIS (Netherlands)

    van Hoorn, Jessika F.; Maathuis, Carel G. B.; Peters, Lieke H. J.; Hadders-Algra, Mijna

    2010-01-01

    Aim The study investigated the relationships between handwriting, visuomotor integration, and neurological condition. We paid particular attention to the presence of minor neurological dysfunction (MND). Method Participants were 200 children (131 males, 69 females; age range 8-13y) of whom 118

  6. Dissociation of agency and body ownership following visuomotor temporal recalibration

    Directory of Open Access Journals (Sweden)

    Shu eImaizumi

    2015-05-01

    Full Text Available Bodily self-consciousness consists of one’s sense of agency (I am causing an action and body ownership (my body belongs to me. Both stem from the temporal congruence between different modalities, although some visuomotor temporal incongruence is acceptable for agency. To examine the association or dissociation between agency and body ownership in the context of different temporal sensitivities, we applied a temporal recalibration paradigm, in which subjective synchrony between asynchronous hand action and its visual feedback can be perceived after exposure to the asynchronous visuomotor stimulation. In the experiment, participants continuously clasped and unclasped their hand while watching an online video of their hand that was presented with delays of 50, 110, 170, 230, 290, and 350 ms. Then, they rated a video of their hand with a delay of 50 ms (test stimulus with respect to the synchrony between hand action and hand video and the perceived agency over the video. Moreover, proprioceptive drift of participants’ hand location toward the hand video during the exposure was measured as an index of illusory body ownership. Results indicated that perception of agency emerged over the delayed hand video as subjective visuomotor synchrony was recalibrated, but that body ownership did not emerge for the delayed video, even after the recalibration. We suggest that there is a dissociation between agency and body ownership following visuomotor temporal recalibration.

  7. Improvements for Image Compression Using Adaptive Principal Component Extraction (APEX)

    Science.gov (United States)

    Ziyad, Nigel A.; Gilmore, Erwin T.; Chouikha, Mohamed F.

    1997-01-01

    The issues of image compression and pattern classification have been a primary focus of researchers among a variety of fields including signal and image processing, pattern recognition, data classification, etc. These issues depend on finding an efficient representation of the source data. In this paper we collate our earlier results where we introduced the application of the. Hilbe.rt scan to a principal component algorithm (PCA) with Adaptive Principal Component Extraction (APEX) neural network model. We apply these technique to medical imaging, particularly image representation and compression. We apply the Hilbert scan to the APEX algorithm to improve results

  8. Visual Motion Processing Subserves Faster Visuomotor Reaction in Badminton Players.

    Science.gov (United States)

    Hülsdünker, Thorben; Strüder, Heiko K; Mierau, Andreas

    2017-06-01

    Athletes participating in ball or racquet sports have to respond to visual stimuli under critical time pressure. Previous studies used visual contrast stimuli to determine visual perception and visuomotor reaction in athletes and nonathletes; however, ball and racquet sports are characterized by motion rather than contrast visual cues. Because visual contrast and motion signals are processed in different cortical regions, this study aimed to determine differences in perception and processing of visual motion between athletes and nonathletes. Twenty-five skilled badminton players and 28 age-matched nonathletic controls participated in this study. Using a 64-channel EEG system, we investigated visual motion perception/processing in the motion-sensitive middle temporal (MT) cortical area in response to radial motion of different velocities. In a simple visuomotor reaction task, visuomotor transformation in Brodmann area 6 (BA6) and BA4 as well as muscular activation (EMG onset) and visuomotor reaction time (VMRT) were investigated. Stimulus- and response-locked potentials were determined to differentiate between perceptual and motor-related processes. As compared with nonathletes, athletes showed earlier EMG onset times (217 vs 178 ms, P < 0.001), accompanied by a faster VMRT (274 vs 243 ms, P < 0.001). Furthermore, athletes showed an earlier stimulus-locked peak activation of MT (200 vs 182 ms, P = 0.002) and BA6 (161 vs 137 ms, P = 0.009). Response-locked peak activation in MT was later in athletes (-7 vs 26 ms, P < 0.001), whereas no group differences were observed in BA6 and BA4. Multiple regression analyses with stimulus- and response-locked cortical potentials predicted EMG onset (r = 0.83) and VMRT (r = 0.77). The athletes' superior visuomotor performance in response to visual motion is primarily related to visual perception and, to a minor degree, to motor-related processes.

  9. Adaptive evolution of synthetic cooperating communities improves growth performance.

    Directory of Open Access Journals (Sweden)

    Xiaolin Zhang

    Full Text Available Symbiotic interactions between organisms are important for human health and biotechnological applications. Microbial mutualism is a widespread phenomenon and is important in maintaining natural microbial communities. Although cooperative interactions are prevalent in nature, little is known about the processes that allow their initial establishment, govern population dynamics and affect evolutionary processes. To investigate cooperative interactions between bacteria, we constructed, characterized, and adaptively evolved a synthetic community comprised of leucine and lysine Escherichia coli auxotrophs. The co-culture can grow in glucose minimal medium only if the two auxotrophs exchange essential metabolites - lysine and leucine (or its precursors. Our experiments showed that a viable co-culture using these two auxotrophs could be established and adaptively evolved to increase growth rates (by ∼3 fold and optical densities. While independently evolved co-cultures achieved similar improvements in growth, they took different evolutionary trajectories leading to different community compositions. Experiments with individual isolates from these evolved co-cultures showed that changes in both the leucine and lysine auxotrophs improved growth of the co-culture. Interestingly, while evolved isolates increased growth of co-cultures, they exhibited decreased growth in mono-culture (in the presence of leucine or lysine. A genome-scale metabolic model of the co-culture was also constructed and used to investigate the effects of amino acid (leucine or lysine release and uptake rates on growth and composition of the co-culture. When the metabolic model was constrained by the estimated leucine and lysine release rates, the model predictions agreed well with experimental growth rates and composition measurements. While this study and others have focused on cooperative interactions amongst community members, the adaptive evolution of communities with other

  10. Visuomotor competencies and primary monosymptomatic nocturnal enuresis in prepubertal aged children

    Directory of Open Access Journals (Sweden)

    Esposito M

    2013-06-01

    -ABC evaluation and in pathologic performance on VMI Total Task compared to controls (P < 0.001. No significant differences between the two study groups were found for pathologic performances on the M-ABC (P = 0.07, VMI Visual Task (P = 0.793, and VMI Motor Task (P = 0.213. Conclusion: Our findings pinpointed that PMNE should not be considered as a voiding disorder alone and, consequently, the children affected should be referred to specific rehabilitative programs that aim to improve motor coordination and visuomotor integration. Keywords: primary monosymptomatic nocturnal enuresis, visuomotor integration, childhood rehabilitation, VMI, M-ABC

  11. Improving Sensorimotor Function and Adaptation using Stochastic Vestibular Stimulation

    Science.gov (United States)

    Galvan, R. C.; Bloomberg, J. J.; Mulavara, A. P.; Clark, T. K.; Merfeld, D. M.; Oman, C. M.

    2014-01-01

    Astronauts experience sensorimotor changes during adaption to G-transitions that occur when entering and exiting microgravity. Post space flight, these sensorimotor disturbances can include postural and gait instability, visual performance changes, manual control disruptions, spatial disorientation, and motion sickness, all of which can hinder the operational capabilities of the astronauts. Crewmember safety would be significantly increased if sensorimotor changes brought on by gravitational changes could be mitigated and adaptation could be facilitated. The goal of this research is to investigate and develop the use of electrical stochastic vestibular stimulation (SVS) as a countermeasure to augment sensorimotor function and facilitate adaptation. For this project, SVS will be applied via electrodes on the mastoid processes at imperceptible amplitude levels. We hypothesize that SVS will improve sensorimotor performance through the phenomena of stochastic resonance, which occurs when the response of a nonlinear system to a weak input signal is optimized by the application of a particular nonzero level of noise. In line with the theory of stochastic resonance, a specific optimal level of SVS will be found and tested for each subject [1]. Three experiments are planned to investigate the use of SVS in sensory-dependent tasks and performance. The first experiment will aim to demonstrate stochastic resonance in the vestibular system through perception based motion recognition thresholds obtained using a 6-degree of freedom Stewart platform in the Jenks Vestibular Laboratory at Massachusetts Eye and Ear Infirmary. A range of SVS amplitudes will be applied to each subject and the subjectspecific optimal SVS level will be identified as that which results in the lowest motion recognition threshold, through previously established, well developed methods [2,3,4]. The second experiment will investigate the use of optimal SVS in facilitating sensorimotor adaptation to system

  12. GENOMIC APPROACHES FOR IMPROVEMENT OF DROUGHT ADAPTATION IN WHEAT

    Directory of Open Access Journals (Sweden)

    Dénes Dudits

    2008-09-01

    Full Text Available Breeding for yield stability under water limited conditions plays an essential role in the reduction of economic and social consequences of global climate changes. We show that two exotic drought resistant genotypes (Kobomughi and Plainsmann differ in root growth rate, root/shoot ratio, and adaptation to low soil water content. These genotypes exhibit characteristic transcript profiles as shown by barley macroarray studies using 10500 unigenes. Reprogramming of gene expression primarily occurred during the 1-2 weeks of water stress, and 6,1% of tested genes were up-regulated in roots of the more adaptive Plainsmann plants. The time course for expression of gene clusters from Kobomughi genotype revealed a prompt and transient gene activation that can help the survival of plants through function of various defense mechanisms. The aldo-keto reductases (AKRs can detoxify lipid peroxidation products (4-hydroxynon-2-enal and glycolysis-derived reactive aldehydes (metylglyoxal that contribute significantly to cellular damages caused by variety of environmental stresses such as drought, high light intensity, UV-B irradiation, cold. Overproduction of AKRs in transgenic tobacco or wheat plants provides considerable stress tolerance and resistance to methylglyoxal. Several transgenic wheat genotypes have been produced with production of elevated level of AKR enzyme. The drought tolerance of these materials was tested by a complex stress diagnostic system, that integrates imaging of plants and monitoring the leaf temperature and fluorescence induction. Based on these parameters, we can conclude that this transgenic strategy that is based on detoxification of lipid aldehyde can result in improved stress adaptation and reduced yield loss.

  13. An Improved Adaptive Tracking Controller of Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Tat-Bao-Thien Nguyen

    2014-01-01

    Full Text Available This paper proposes a new adaptive fuzzy neural control to suppress chaos and also to achieve the speed tracking control in a permanent magnet synchronous motor (PMSM drive system with unknown parameters and uncertainties. The control scheme consists of fuzzy neural and compensatory controllers. The fuzzy neural controller with online parameter tuning is used to estimate the unknown nonlinear models and construct linearization feedback control law, while the compensatory controller is employed to attenuate the estimation error effects of the fuzzy neural network and ensure the robustness of the controlled system. Moreover, due to improvement in controller design, the singularity problem is surely avoided. Finally, numerical simulations are carried out to demonstrate that the proposed control scheme can successfully remove chaotic oscillations and allow the speed to follow the desired trajectory in a chaotic PMSM despite the existence of unknown models and uncertainties.

  14. Cross-sectional evaluation of visuomotor tracking performance following subconcussive head impacts.

    Science.gov (United States)

    Brokaw, E B; Fine, M S; Kindschi, K E; Santago Ii, A C; Lum, P S; Higgins, M

    2017-11-03

    Repeated mild traumatic brain injury (mTBI) has been associated with increased risk of degenerative neurological disorders. While the effects of mTBI and repeated injury are known, studies have only recently started examining repeated subconcussive impacts, impacts that do not result in a clinically diagnosed mTBI. In these studies, repeated subconcussive impacts have been connected to cognitive performance and brain imaging changes. Recent research suggests that performance on a visuomotor tracking (VMT) task may help improve the identification of mTBI. The goal of this study was to investigate if VMT performance is sensitive to the cumulative effect of repeated subconcussive head impacts in collegiate men's lacrosse players. A cross-sectional, prospective study was completed with eleven collegiate men's lacrosse players. Participants wore helmet-mounted sensors and completed VMT and reaction time assessments. The relationship between cumulative impact metrics and VMT metrics were investigated. In this study, VMT performance correlated with repeated subconcussive head impacts; individuals approached clinically diagnosed mTBI-like performance as the cumulative rotational velocity they experienced increased. This suggests that repeated subconcussive impacts can result in measurable impairments and indicates that visuomotor tracking performance may be a useful tool for monitoring the effects of repeated subconcussive impacts.

  15. Brief Morning Light Exposure, Visuomotor Performance, and Biochemistry in Sport Shooters.

    Science.gov (United States)

    Leichtfried, Veronika; Hanser, Friedrich; Griesmacher, Andrea; Canazei, Markus; Schobersberger, Wolfgang

    2016-09-01

    Demands on concentrative and cognitive performance are high in sport shooting and vary in a circadian pattern, aroused by internal and external stimuli. The most prominent external stimulus is light. Bright light (BL) has been shown to have a certain impact on cognitive and physical performance. To evaluate the impact of a single half hour of BL exposure in the morning hours on physical and cognitive performance in 15 sport shooters. In addition, courses of sulfateoxymelatonin (aMT6s), tryptophan (TRP), and kynurenine (KYN) were monitored. In a crossover design, 15 sport shooters were exposed to 30 min of BL and dim light (DL) in the early-morning hours. Shooting performance, balance, visuomotor performance, and courses of aMT6s, TRP, and KYN were evaluated. Shooting performance was 365.4 (349.7-381.0) and 368.5 (353.9-383.1), identical in both light setups. Numbers of right reactions (sustained attention) and deviations from the horizontal plane (balance-related measure) were higher after BL. TRP concentrations decreased from 77.5 (73.5-81.4) to 66.9 (60.7-67.0) in the DL setup only. The 2 light conditions generated heterogeneous visuomotor and physiological effects in sport shooters. The authors therefore suggest that a single half hour of BL exposure is effective in improving cognitive aspects of performance, but not physical performance. Further research is needed to evaluate BL's impact on biochemical parameters.

  16. Anticholinergic activity in the nervous system: Consequences for visuomotor function.

    Science.gov (United States)

    Naicker, Preshanta; Anoopkumar-Dukie, Shailendra; Grant, Gary D; Kavanagh, Justin J

    2017-03-01

    Acetylcholine is present in the peripheral and central nervous system, where it is involved in a number of fundamental physiological and biochemical processes. In particular, interaction with muscarinic receptors can cause adverse effects such as dry mouth, drowsiness, mydriasis and cognitive dysfunction. Despite the knowledge that exists regarding these common side-effects, little is known about how anticholinergic medications influence central motor processes and fine motor control in healthy individuals. This paper reviews critical visuomotor processes that operate in healthy individuals, and how controlling these motor processes are influenced by medications that interfere with central cholinergic neurotransmission. An overview of receptor function and neurotransmitter interaction following the ingestion or administration of anticholinergics is provided, before exploring how visuomotor performance is affected by anticholinergic medications. In particular, this review will focus on the effects that anticholinergic medications have on fixation stability, saccadic eye movements, smooth pursuit eye movements, and general pupil dynamics. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Improving Adaptive Learning Technology through the Use of Response Times

    Science.gov (United States)

    Mettler, Everett; Massey, Christine M.; Kellman, Philip J.

    2011-01-01

    Adaptive learning techniques have typically scheduled practice using learners' accuracy and item presentation history. We describe an adaptive learning system (Adaptive Response Time Based Sequencing--ARTS) that uses both accuracy and response time (RT) as direct inputs into sequencing. Response times are used to assess learning strength and…

  18. Improving Accuracy of Processing by Adaptive Control Techniques

    Directory of Open Access Journals (Sweden)

    N. N. Barbashov

    2016-01-01

    Full Text Available When machining the work-pieces a range of scatter of the work-piece dimensions to the tolerance limit is displaced in response to the errors. To improve an accuracy of machining and prevent products from defects it is necessary to diminish the machining error components, i.e. to improve the accuracy of machine tool, tool life, rigidity of the system, accuracy of adjustment. It is also necessary to provide on-machine adjustment after a certain time. However, increasing number of readjustments reduces the performance and high machine and tool requirements lead to a significant increase in the machining cost.To improve the accuracy and machining rate, various devices of active control (in-process gaging devices, as well as controlled machining through adaptive systems for a technological process control now become widely used. Thus, the accuracy improvement in this case is reached by compensation of a majority of technological errors. The sensors of active control can provide improving the accuracy of processing by one or two quality classes, and simultaneous operation of several machines.For efficient use of sensors of active control it is necessary to develop the accuracy control methods by means of introducing the appropriate adjustments to solve this problem. Methods based on the moving average, appear to be the most promising for accuracy control, since they contain information on the change in the last several measured values of the parameter under control.When using the proposed method in calculation, the first three members of the sequence of deviations remain unchanged, therefore 1 1 x  x , 2 2 x  x , 3 3 x  x Then, for each i-th member of the sequence we calculate that way: , ' i i i x  x  k x , where instead of the i x values will be populated with the corresponding values ' i x calculated as an average of three previous members:3 ' 1  2  3  i i i i x x x x .As a criterion for the estimate of the control

  19. LEACH-A: An Adaptive Method for Improving LEACH Protocol

    Directory of Open Access Journals (Sweden)

    Jianli ZHAO

    2014-01-01

    Full Text Available Energy has become one of the most important constraints on wireless sensor networks. Hence, many researchers in this field focus on how to design a routing protocol to prolong the lifetime of the network. The classical hierarchical protocols such as LEACH and LEACH-C have better performance in saving the energy consumption. However, the choosing strategy only based on the largest residue energy or shortest distance will still consume more energy. In this paper an adaptive routing protocol named “LEACH-A” which has an energy threshold E0 is proposed. If there are cluster nodes whose residual energy are greater than E0, the node of largest residual energy is selected to communicated with the base station; When all the cluster nodes energy are less than E0, the node nearest to the base station is select to communication with the base station. Simulations show that our improved protocol LEACH-A performs better than the LEACH and the LEACH-C.

  20. Visuomotor learning by passive motor experience

    Directory of Open Access Journals (Sweden)

    Takashi eSakamoto

    2015-05-01

    Full Text Available Humans can adapt to unfamiliar dynamic and/or kinematic transformations through the active motor experience. Recent studies of neurorehabilitation using robots or brain-computer interface (BCI technology suggest that passive motor experience would play a measurable role in motor recovery, however our knowledge of passive motor learning is limited. To clarify the effects of passive motor experience on human motor learning, we performed arm reaching experiments guided by a robotic manipulandum. The results showed that the passive motor experience had an anterograde transfer effect on the subsequent motor execution, whereas no retrograde interference was confirmed in the ABA paradigm experiment. This suggests that the passive experience of the error between visual and proprioceptive sensations leads to the limited but actual compensation of behavior, although it is fragile and cannot be consolidated as a persistent motor memory.

  1. Different Evolutionary Origins for the Reach and the Grasp: An Explanation for Dual Visuomotor Channels in Primate Parietofrontal Cortex

    Directory of Open Access Journals (Sweden)

    Jenni M Karl

    2013-12-01

    Full Text Available The Dual Visuomotor Channel Theory proposes that manual prehension consists of two temporally integrated movements, each subserved by distinct visuomotor pathways in occipitoparietofrontal cortex. The Reach is mediated by a dorsomedial pathway and transports the hand in relation to the target’s extrinsic properties (i.e., location and orientation. The Grasp is mediated by a dorsolateral pathway and opens, preshapes, and closes the hand in relation to the target’s intrinsic properties (i.e., size and shape. Here, neuropsychological, developmental, and comparative evidence is reviewed to show that the Reach and the Grasp have different evolutionary origins. First, the removal or degradation of vision causes prehension to decompose into its constituent Reach and Grasp components, which are then executed in sequence or isolation. Similar decomposition occurs in optic ataxic patients following cortical injury to the Reach and Grasp pathways and after corticospinal tract lesions in non-human primates. Second, early nonvisual PreReach and PreGrasp movements develop into mature Reach and Grasp movements but are only integrated under visual control after a prolonged developmental period. Third, comparative studies reveal many similarities between stepping movements and the Reach and between food handling movements and the Grasp, suggesting that the Reach and Grasp are derived from different evolutionary antecedents. The evidence is discussed in relation to the ideas that dual visuomotor channels in primate parietofrontal cortex emerged as a result of distinct evolutionary origins for the Reach and Grasp; that foveated vision in primates serves to integrate the Reach and Grasp into a single prehensile act; and, that flexible recombination of discrete Reach and Grasp movements under various forms of sensory and cognitive control can produce adaptive behavior.

  2. Improved Gaussian Mixture Models for Adaptive Foreground Segmentation

    DEFF Research Database (Denmark)

    Katsarakis, Nikolaos; Pnevmatikakis, Aristodemos; Tan, Zheng-Hua

    2016-01-01

    elements to the baseline algorithm: The learning rate can change across space and time, while the Gaussian distributions can be merged together if they become similar due to their adaptation process. We quantify the importance of our enhancements and the effect of parameter tuning using an annotated......Adaptive foreground segmentation is traditionally performed using Stauffer & Grimson’s algorithm that models every pixel of the frame by a mixture of Gaussian distributions with continuously adapted parameters. In this paper we provide an enhancement of the algorithm by adding two important dynamic...

  3. Practice effects reveal visuomotor vulnerability in school and university rugby players.

    Science.gov (United States)

    Shuttleworth-Edwards, Ann B; Radloff, Sarah E; Whitefield-Alexander, Victoria J; Smith, Ian P; Horsman, Mark

    2014-02-01

    This article reports on three pre- versus post-season prospective studies in which male university and high school contact sport players predominantly of Rugby Union (hereafter rugby) were compared with age, education, and IQ equivalent non-contact sport controls on the ImPACT (Immediate Postconcussion Assessment and Cognitive Testing) test. All analyses revealed a relative absence of practice effects on the Visual Motor Speed (VMS) composite for contact sport groups compared with controls. The VMS data for rugby players from each study were pooled and subjected to additional analysis (Rugby, n = 145; Controls, n = 106). Controls revealed significant improvement over the season (p rugby players whose performance remained the same (interaction effect, p = .028). It is apparent that practice effects have diagnostic potential in this context, implicating vulnerability on speeded visuomotor processing in association with participation in rugby. Pointers for further research and concussion management in the individual case are explored.

  4. Adaptation to Climatic Hazards in the Savannah Ecosystem: Improving Adaptation Policy and Action

    Science.gov (United States)

    Yiran, Gerald A. B.; Stringer, Lindsay C.

    2017-10-01

    People in Ghana's savannah ecosystem have historically experienced a range of climatic hazards that have affected their livelihoods. In view of current climate variability and change, and projected increases in extreme events, adaptation to climate risks is vital. Policies have been put in place to enhance adaptation across sub-Saharan Africa in accordance with international agreements. At the same time, local people, through experience, have learned to adapt. This paper examines current policy actions and their implementation alongside an assessment of barriers to local adaptation. In doing so it links adaptation policy and practice. Policy documents were analysed that covered key livelihood sectors, which were identified as climate sensitive. These included agriculture, water, housing and health policies, as well as the National Climate Change Policy. In-depth interviews and focus group discussions were also held with key stakeholders in the Upper East Region of Ghana. Analyses were carried using thematic content analysis. Although policies and actions complement each other, their integration is weak. Financial, institutional, social, and technological barriers hinder successful local implementation of some policy actions, while lack of local involvement in policy formulation also hinders adaptation practice. Integration of local perspectives into policy needs to be strengthened in order to enhance adaptation. Coupled with this is a need to consider adaptation to climate change in development policies and to pursue efforts to reduce or remove the key barriers to implementation at the local level.

  5. CleanTag Adapters Improve Small RNA Next-Generation Sequencing Library Preparation by Reducing Adapter Dimers.

    Science.gov (United States)

    Shore, Sabrina; Henderson, Jordana M; McCaffrey, Anton P

    2018-01-01

    Next-generation small RNA sequencing is a valuable tool which is increasing our knowledge regarding small noncoding RNAs and their function in regulating genetic information. Library preparation protocols for small RNA have thus far been restricted due to higher RNA input requirements (>10 ng), long workflows, and tedious manual gel purifications. Small RNA library preparation methods focus largely on the prevention or depletion of a side product known as adapter dimer that tends to dominate the reaction. Adapter dimer is the ligation of two adapters to one another without an intervening library RNA insert or any useful sequencing information. The amplification of this side reaction is favored over the amplification of tagged library since it is shorter. The small size discrepancy between these two species makes separation and purification of the tagged library very difficult. Adapter dimer hinders the use of low input samples and the ability to automate the workflow so we introduce an improved library preparation protocol which uses chemically modified adapters (CleanTag) to significantly reduce the adapter dimer. CleanTag small RNA library preparation workflow decreases adapter dimer to allow for ultra-low input samples (down to approx. 10 pg total RNA), elimination of the gel purification step, and automation. We demonstrate how to carry out this streamlined protocol to improve NGS data quality and allow for the use of sample types with limited RNA material.

  6. Optic flow improves adaptability of spatiotemporal characteristics during split-belt locomotor adaptation with tactile stimulation.

    Science.gov (United States)

    Eikema, Diderik Jan A; Chien, Jung Hung; Stergiou, Nicholas; Myers, Sara A; Scott-Pandorf, Melissa M; Bloomberg, Jacob J; Mukherjee, Mukul

    2016-02-01

    Human locomotor adaptation requires feedback and feed-forward control processes to maintain an appropriate walking pattern. Adaptation may require the use of visual and proprioceptive input to decode altered movement dynamics and generate an appropriate response. After a person transfers from an extreme sensory environment and back, as astronauts do when they return from spaceflight, the prolonged period required for re-adaptation can pose a significant burden. In our previous paper, we showed that plantar tactile vibration during a split-belt adaptation task did not interfere with the treadmill adaptation however, larger overground transfer effects with a slower decay resulted. Such effects, in the absence of visual feedback (of motion) and perturbation of tactile feedback, are believed to be due to a higher proprioceptive gain because, in the absence of relevant external dynamic cues such as optic flow, reliance on body-based cues is enhanced during gait tasks through multisensory integration. In this study, we therefore investigated the effect of optic flow on tactile-stimulated split-belt adaptation as a paradigm to facilitate the sensorimotor adaptation process. Twenty healthy young adults, separated into two matched groups, participated in the study. All participants performed an overground walking trial followed by a split-belt treadmill adaptation protocol. The tactile group (TC) received vibratory plantar tactile stimulation only, whereas the virtual reality and tactile group (VRT) received an additional concurrent visual stimulation: a moving virtual corridor, inducing perceived self-motion. A post-treadmill overground trial was performed to determine adaptation transfer. Interlimb coordination of spatiotemporal and kinetic variables was quantified using symmetry indices and analyzed using repeated-measures ANOVA. Marked changes of step length characteristics were observed in both groups during split-belt adaptation. Stance and swing time symmetries were

  7. Improving the evidence for ecosystem-based adaptation

    Energy Technology Data Exchange (ETDEWEB)

    Reid, Hannah

    2011-11-15

    Ecosystem-based approaches to adaptation (EBA) integrate the use of biodiversity and ecosystem services into an overall strategy for helping people adapt to climate change. The body of scientific evidence that indicates how effective they are is in some cases lacking but in other cases is dispersed across a range of related fields, such as natural resource management, disaster risk reduction and agroecology, from which it needs to be synthesised. Without presenting and strengthening this evidence in a consolidated way, EBA cannot secure the policy traction at local, national and international levels that it merits.

  8. Improving farmer adaptive capacity by integrating local and ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2016-04-22

    Apr 22, 2016 ... Despite the availability of more reliable forecasts from meteorological services in Kenya, farmers seldom use them for farm level decision-making. This case study discusses how downscaled forecasts and more accessible climate information can enhance the adaptive capacity of small-holder farmers.

  9. Improving farmer adaptive capacity by integrating local and ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    22 avr. 2016 ... Research led by Sokoine University of Agriculture demonstrates the usefulness of integrating seasonal climate forecasting with farm management activities in the uncertainty of changing climate patterns. Download the PDF. This brief resulted from two projects supported by the Climate Change Adaptation ...

  10. The Build-Up Course of Visuo-Motor and Audio-Motor Temporal Recalibration

    Directory of Open Access Journals (Sweden)

    Yoshimori Sugano

    2011-10-01

    Full Text Available The sensorimotor timing is recalibrated after a brief exposure to a delayed feedback of voluntary actions (temporal recalibration effect: TRE (Heron et al., 2009; Stetson et al., 2006; Sugano et al., 2010. We introduce a new paradigm, namely ‘synchronous tapping’ (ST which allows us to investigate how the TRE builds up during adaptation. In each experimental trial, participants were repeatedly exposed to a constant lag (∼150 ms between their voluntary action (pressing a mouse and a feedback stimulus (a visual flash / an auditory click 10 times. Immediately after that, they performed a ST task with the same stimulus as a pace signal (7 flashes / clicks. A subjective ‘no-delay condition’ (∼50 ms served as control. The TRE manifested itself as a change in the tap-stimulus asynchrony that compensated the exposed lag (eg, after lag adaptation, the tap preceded the stimulus more than in control and built up quickly (∼3–6 trials, ∼23–45 sec in both the visuo- and audio-motor domain. The audio-motor TRE was bigger and built-up faster than the visuo-motor one. To conclude, the TRE is comparable between visuo- and audio-motor domain, though they are slightly different in size and build-up rate.

  11. Effects of context on visuomotor interference depends on the perspective of observed actions.

    Directory of Open Access Journals (Sweden)

    Marta Bortoletto

    Full Text Available Visuomotor interference occurs when the execution of an action is facilitated by the concurrent observation of the same action and hindered by the concurrent observation of a different action. There is evidence that visuomotor interference can be modulated top-down by higher cognitive functions, depending on whether own performed actions or observed actions are selectively attended. Here, we studied whether these effects of cognitive context on visuomotor interference are also dependent on the point-of-view of the observed action. We employed a delayed go/no-go task known to induce visuomotor interference. Static images of hand gestures in either egocentric or allocentric perspective were presented as "go" stimuli after participants were pre-cued to prepare either a matching (congruent or non-matching (incongruent action. Participants performed this task in two different cognitive contexts: In one, they focused on the visual image of the hand gesture shown as the go stimulus (image context, whereas in the other they focused on the hand gesture they performed (action context. We analyzed reaction times to initiate the prepared action upon presentation of the gesture image and found evidence of visuomotor interference in both contexts and for both perspectives. Strikingly, results show that the effect of cognitive context on visuomotor interference also depends on the perspective of observed actions. When focusing on own-actions, visuomotor interference was significantly less for gesture images in allocentric perspective than in egocentric perspective; when focusing on observed actions, visuomotor interference was present regardless of the perspective of the gesture image. Overall these data suggest that visuomotor interference may be modulated by higher cognitive processes, so that when we are specifically attending to our own actions, images depicting others' actions (allocentric perspective have much less interference on our own actions.

  12. Adaptive prefetching on POWER7: Improving performance and power consumption

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, Victor [Barcelona Supercomputing Center and Univ. Politecnica de Catalunya, Barcelona (Spain); Cazorla, Francisco [Barcelona Supercomputing Center and Univ. Politecnica de Catalunya, Barcelona (Spain); Gioiosa, Roberto [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Buyuktosunoglu, Alper [IBM T. J. Watson Research Center, Yorktown Heights, NY (United States); Bose, Pradip [IBM T. J. Watson Research Center, Yorktown Heights, NY (United States); O' Connel, Francis P. [IBM T. J. Watson Research Center, Yorktown Heights, NY (United States); Mealey, Bruce G. [IBM T. J. Watson Research Center, Yorktown Heights, NY (United States)

    2014-10-03

    Hardware data prefetch engines are integral parts of many general purpose server-class microprocessors in the field today. Some prefetch engines allow users to change some of their parameters. But, the prefetcher is usually enabled in a default configuration during system bring-up, and dynamic reconfiguration of the prefetch engine is not an autonomic feature of current machines. Conceptually, however, it is easy to infer that commonly used prefetch algorithms—when applied in a fixed mode—will not help performance in many cases. In fact, they may actually degrade performance due to useless bus bandwidth consumption and cache pollution, which in turn, will also waste power. We present an adaptive prefetch scheme that dynamically modifies the prefetch settings in order to adapt to workloads

  13. Auditory-Perceptual Learning Improves Speech Motor Adaptation in Children

    OpenAIRE

    Shiller, Douglas M.; Rochon, Marie-Lyne

    2014-01-01

    Auditory feedback plays an important role in children’s speech development by providing the child with information about speech outcomes that is used to learn and fine-tune speech motor plans. The use of auditory feedback in speech motor learning has been extensively studied in adults by examining oral motor responses to manipulations of auditory feedback during speech production. Children are also capable of adapting speech motor patterns to perceived changes in auditory feedback, however it...

  14. Neural network based adaptive output feedback control: Applications and improvements

    Science.gov (United States)

    Kutay, Ali Turker

    Application of recently developed neural network based adaptive output feedback controllers to a diverse range of problems both in simulations and experiments is investigated in this thesis. The purpose is to evaluate the theory behind the development of these controllers numerically and experimentally, identify the needs for further development in practical applications, and to conduct further research in directions that are identified to ultimately enhance applicability of adaptive controllers to real world problems. We mainly focus our attention on adaptive controllers that augment existing fixed gain controllers. A recently developed approach holds great potential for successful implementations on real world applications due to its applicability to systems with minimal information concerning the plant model and the existing controller. In this thesis the formulation is extended to the multi-input multi-output case for distributed control of interconnected systems and successfully tested on a formation flight wind tunnel experiment. The command hedging method is formulated for the approach to further broaden the class of systems it can address by including systems with input nonlinearities. Also a formulation is adopted that allows the approach to be applied to non-minimum phase systems for which non-minimum phase characteristics are modeled with sufficient accuracy and treated properly in the design of the existing controller. It is shown that the approach can also be applied to augment nonlinear controllers under certain conditions and an example is presented where the nonlinear guidance law of a spinning projectile is augmented. Simulation results on a high fidelity 6 degrees-of-freedom nonlinear simulation code are presented. The thesis also presents a preliminary adaptive controller design for closed loop flight control with active flow actuators. Behavior of such actuators in dynamic flight conditions is not known. To test the adaptive controller design in

  15. Improving personality facet scores with multidimensional computer adaptive testing

    DEFF Research Database (Denmark)

    Makransky, Guido; Mortensen, Erik Lykke; Glas, Cees A W

    2013-01-01

    personality tests contain many highly correlated facets. This article investigates the possibility of increasing the precision of the NEO PI-R facet scores by scoring items with multidimensional item response theory and by efficiently administering and scoring items with multidimensional computer adaptive...... testing (MCAT). The increase in the precision of personality facet scores is obtained from exploiting the correlations between the facets. Results indicate that the NEO PI-R could be substantially shorter without attenuating precision when the MCAT methodology is used. Furthermore, the study shows...

  16. Adaptive optics for improved retinal surgery and diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Humayun, M S; Sadda, S R; Thompson, C A; Olivier, S S; Kartz, M W

    2000-08-21

    It is now possible to field a compact adaptive optics (AO) system on a surgical microscope for use in retinal diagnostics and surgery. Recent developments in integrated circuit technology and optical photonics have led to the capability of building an AO system that is compact and significantly less expensive than traditional AO systems. It is foreseen that such an AO system can be integrated into a surgical microscope while maintaining a package size of a lunchbox. A prototype device can be developed in a manner that lends itself well to large-scale manufacturing.

  17. Simultaneous expression of regulatory genes associated with specific drought-adaptive traits improves drought adaptation in peanut.

    Science.gov (United States)

    Ramu, Vemanna S; Swetha, Thavarekere N; Sheela, Shekarappa H; Babitha, Chandrashekar K; Rohini, Sreevathsa; Reddy, Malireddy K; Tuteja, Narendra; Reddy, Chandrashekar P; Prasad, Trichi Ganesh; Udayakumar, Makarla

    2016-03-01

    Adaptation of crops to drought-prone rain-fed conditions can be achieved by improving plant traits such as efficient water mining (by superior root characters) and cellular-level tolerance mechanisms. Pyramiding these drought-adaptive traits by simultaneous expression of genes regulating drought-adaptive mechanisms has phenomenal relevance in improving stress tolerance. In this study, we provide evidence that peanut transgenic plants expressing Alfalfa zinc finger 1 (Alfin1), a root growth-associated transcription factor gene, Pennisetum glaucum heat-shock factor (PgHSF4) and Pea DNA helicase (PDH45) involved in protein turnover and protection showed improved tolerance, higher growth and productivity under drought stress conditions. Stable integration of all the transgenes was noticed in transgenic lines. The transgenic lines showed higher root growth, cooler crop canopy air temperature difference (less CCATD) and higher relative water content (RWC) under drought stress. Low proline levels in transgenic lines substantiate the maintenance of higher water status. The survival and recovery of transgenic lines was significantly higher under gradual moisture stress conditions with higher biomass. Transgenic lines also showed significant tolerance to ethrel-induced senescence and methyl viologen-induced oxidative stress. Several stress-responsive genes such as heat-shock proteins (HSPs), RING box protein-1 (RBX1), Aldose reductase, late embryogenesis abundant-5 (LEA5) and proline-rich protein-2 (PRP2), a gene involved in root growth, showed enhanced expression under stress in transgenic lines. Thus, the simultaneous expression of regulatory genes contributing for drought-adaptive traits can improve crop adaptation and productivity under water-limited conditions. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  18. An Improved Adaptive Deconvolution Algorithm for Single Image Deblurring

    Directory of Open Access Journals (Sweden)

    Hsin-Che Tsai

    2014-01-01

    Full Text Available One of the most common defects in digital photography is motion blur caused by camera shake. Shift-invariant motion blur can be modeled as a convolution of the true latent image and a point spread function (PSF with additive noise. The goal of image deconvolution is to reconstruct a latent image from a degraded image. However, ringing is inevitable artifacts arising in the deconvolution stage. To suppress undesirable artifacts, regularization based methods have been proposed using natural image priors to overcome the ill-posedness of deconvolution problem. When the estimated PSF is erroneous to some extent or the PSF size is large, conventional regularization to reduce ringing would lead to loss of image details. This paper focuses on the nonblind deconvolution by adaptive regularization which preserves image details, while suppressing ringing artifacts. The way is to control the regularization weight adaptively according to the image local characteristics. We adopt elaborated reference maps that indicate the edge strength so that textured and smooth regions can be distinguished. Then we impose an appropriate constraint on the optimization process. The experiments’ results on both synthesized and real images show that our method can restore latent image with much fewer ringing and favors the sharp edges.

  19. Visuomotor impairments in older adults at increased Alzheimer's disease risk.

    Science.gov (United States)

    Hawkins, Kara M; Sergio, Lauren E

    2014-01-01

    Recent evidence suggests that visuomotor behaviors may be disrupted in the very early stages of Alzheimer's disease (AD). Here we propose that using kinematic measures under conditions that place demands on visual-spatial and cognitive-motor processing may provide an effective behavioral means to detect subtle changes associated with AD risk. To this end, we have tested 22 young adults (mean age = 26.4 ± 4.1) and 22 older adults (mean age = 64.3 ± 10.1) at low AD, and 22 older adults (mean age = 67.7 ± 11.3) at high AD risk (i.e., strong family history or diagnosis of mild cognitive impairment). Kinematic measures were acquired on four visuomotor transformation tasks (standard, feedback reversal, plane dissociated, and plane dissociated + feedback reversal) using a dual-touchscreen tablet. Comparing participants at increased AD risk with both young and old healthy control groups revealed significant performance disruptions in at-risk individuals as task demands increased. Furthermore, we were able to discriminate between individuals at high and low AD risk with a classification accuracy of 86.4% (sensitivity: 81.8%, specificity: 90.9%). We suggest that the impairments observed in individuals at increased AD risk may reflect inherent brain alteration and/or early neuropathology disrupting the reciprocal communication between hippocampal, parietal, and frontal brain regions required to successfully prepare and update complex reaching movements. Such impairment has the potential to affect activities of daily living, and may serve as a sensitive measure of functional ability in at-risk adults.

  20. Decreased effective connectivity in the visuomotor system after alcohol consumption.

    Science.gov (United States)

    Luchtmann, Michael; Jachau, Katja; Adolf, Daniela; Baecke, Sebastian; Lützkendorf, Ralf; Müller, Charles; Tempelmann, Claus; Bernarding, Johannes

    2013-05-01

    Functional magnetic resonance imaging (fMRI) allows observing cerebral activity not only in separated cortical regions but also in functionally coupled cortical networks. Although moderate doses of ethanol slowdown the neurovascular coupling, the functions of the primary sensorimotor and the visual system remain intact. Yet little is known about how more complex interactions between cortical regions are affected even at moderate doses of alcohol. Therefore the method of psychophysiological interaction (PPI) was applied to analyze ethanol-induced effects on the effective connectivity in the visuomotor system. Fourteen healthy social drinkers with no personal history of neurological disorders or substance abuse were examined. In a test/re-test design they served as their own controls by participating in both the sober and the ethanol condition. All participants were scanned in a 3 T MR scanner before and after ingestion of a body-weight-dependent amount of ethanol calculated to achieve a blood alcohol concentration of 1.0‰. PPIs were calculated for the primary visual cortex, the supplementary motor area, and the left and right primary motor cortex using the statistical software package SPM. The PPI analysis showed selective disturbance of the effective connectivity between different cortical areas. The regression analysis revealed the influence of the supplementary motor area on connected regions like the primary motor cortex to be decreased yet preserved. However, the connection between the primary visual cortex and the posterior parietal cortex was more severely impaired by the influence of ethanol, leading to an uncoupled regression between these regions. The decreased effective connectivity in the visuomotor system suggests that complex tasks requiring interaction or synchronization between different brain areas are affected even at moderate levels of alcohol. This finding may have important consequences for determining which components of demanding tasks such

  1. A technique for improved stability of adaptive feedforward controllers without detailed uncertainty measurements

    NARCIS (Netherlands)

    Berkhoff, Arthur P.

    Model errors in adaptive controllers for reduction of broadband noise and vibrations may lead to unstable systems or increased error signals. Previous work has shown that the addition of a low-authority controller that increases damping in the system may lead to improved performance of an adaptive,

  2. A technique for improved stability of adaptive feedforward controllers without detailed uncertainty measurements

    NARCIS (Netherlands)

    Berkhoff, A.P.

    2011-01-01

    Model errors in adaptive controllers for reduction of broadband noise and vibrations may lead to unstable systems or increased error signals. Previous work has shown that the addition of a low-authority controller that increases damping in the system may lead to improved performance of an adaptive,

  3. Improved probabilistic neural networks with self-adaptive strategies for transformer fault diagnosis problem

    Directory of Open Access Journals (Sweden)

    Jiao-Hong Yi

    2016-01-01

    Full Text Available Probabilistic neural network has successfully solved all kinds of engineering problems in various fields since it is proposed. In probabilistic neural network, Spread has great influence on its performance, and probabilistic neural network will generate bad prediction results if it is improperly selected. It is difficult to select the optimal manually. In this article, a variant of probabilistic neural network with self-adaptive strategy, called self-adaptive probabilistic neural network, is proposed. In self-adaptive probabilistic neural network, Spread can be self-adaptively adjusted and selected and then the best selected Spread is used to guide the self-adaptive probabilistic neural network train and test. In addition, two simplified strategies are incorporated into the proposed self-adaptive probabilistic neural network with the aim of further improving its performance and then two versions of simplified self-adaptive probabilistic neural network (simplified self-adaptive probabilistic neural networks 1 and 2 are proposed. The variants of self-adaptive probabilistic neural networks are further applied to solve the transformer fault diagnosis problem. By comparing them with basic probabilistic neural network, and the traditional back propagation, extreme learning machine, general regression neural network, and self-adaptive extreme learning machine, the results have experimentally proven that self-adaptive probabilistic neural networks have a more accurate prediction and better generalization performance when addressing the transformer fault diagnosis problem.

  4. Direct effects of prismatic lenses on visuomotor control: an event-related functional MRI study.

    Science.gov (United States)

    Danckert, James; Ferber, Susanne; Goodale, Melvyn A

    2008-10-01

    Exposure to prisms has long been used to explore the control of visually guided actions primarily because adaptation requires the recalibration of misaligned reference frames due to perturbed visual input (i.e. eye-in-head and hand-centered reference frames must be realigned). To date, the only neuroimaging study to explore the direct effects of prisms on pointing used positron emission tomography and found increased activation only in right parietal cortex. We used event-related functional MRI to examine the effects of prisms on visuomanual pointing. Results demonstrated changes in activity in the anterior cingulate, the anterior intraparietal region and in a medial region of the right cerebellum. Specifically, activity in these regions was higher for the first few pointing trials made while viewing targets through prisms when directly contrasted to the last few trials. These results highlight that a more extensive network of cortical and cerebellar regions is involved in recalibrating visuomotor commands in the face of perturbed visual input.

  5. Adaptive Computer-Assisted Mammography Training for Improved Breast Cancer Screening

    Science.gov (United States)

    2015-03-01

    detection in mammography ." Medical Physics 31: 958. Timp, S., N. Karssemeijer and J. Hendriks (2003). Analysis of changes in masses using contrast and...Award Number: W81XWH-11-1-0755 TITLE: Adaptive Computer-Assisted Mammography Training for Improved Breast Cancer Screening PRINCIPAL...14Dec2014 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER W81XWH-11-1-0755 Adaptive Computer-Assisted Mammography Training for Improved Breast Cancer

  6. An improved adaptive wavelet shrinkage for ultrasound despeckling

    Indian Academy of Sciences (India)

    ... Perundurai 638 052, India. 2Department of Electronics and Communication Engineering, Kongunadu College of. Engineering and Technology, Thottiyam 621 ... ter achieves an improvement in terms of quantitative measures and in terms of visual quality of the images. Keywords. Wavelet; translation invariance; inter and ...

  7. An improved adaptive wavelet shrinkage for ultrasound despeckling

    Indian Academy of Sciences (India)

    A comparison of the results shows that the proposed filter achieves an improvement in terms of quantitative measures and in terms of visual quality of the images. ... Kongu Engineering College, Perundurai 638 052, India; Department of Electronics and Communication Engineering, Kongunadu College of Engineering and ...

  8. MOOC Adaptation and Translation to Improve Equity in Participation

    Science.gov (United States)

    Wolfenden, Freda; Cross, Simon; Henry, Fiona

    2017-01-01

    There is an urgent need to improve elementary and secondary school classroom practices across India and the scale of this challenge is argued to demand new approaches to teacher professional learning. Massive Open Online Courses (MOOCs) represent one such approach and one that, in the context of this study, is considered to provide a means by…

  9. Adapting Job Analysis Methodology to Improve Evaluation Practice

    Science.gov (United States)

    Jenkins, Susan M.; Curtin, Patrick

    2006-01-01

    This article describes how job analysis, a method commonly used in personnel research and organizational psychology, provides a systematic method for documenting program staffing and service delivery that can improve evaluators' knowledge about program operations. Job analysis data can be used to increase evaluators' insight into how staffs…

  10. Adapting workload improves the measurement of heart rate recovery.

    Science.gov (United States)

    Lamberts, R P; Maskell, S; Borresen, J; Lambert, M I

    2011-09-01

    Heart rate after a standardized test varies with a change in training status, possibly compromising the accuracy of measuring changes in heart rate recovery (HRR). The aim of this study was to determine if a change in the exercise intensity would result in a change in heart rate recovery and/or the accuracy of the heart rate recovery measurement. 31 subjects performed 4 submaximal running tests (HIMS). Based on the heart rate after the first HIMS, subjects either completed 4 identical HIMS (SAME (n=9)), 2 standard and 2 faster HIMS (FASTER (n=10)) or 2 standard and 2 slower HIMS (SLOWER (n=12)). Although no changes in heart rate recovery were found when the HIMS protocol was adapted, lower coefficients of variation (CV) and typical errors of measurement (TEM) were found in the SLOWER (CV: 11 ± 7 to 5 ± 3% ( P=0.025)), TEM: 6 to 3 beats and FASTER group (CV: 11 ± 7 to 4 ± 3% ( P=0.048), TEM: 7 to 3 beats). To ensure the highest level of sensitivity in detecting meaningful changes in HRR over time, submaximal testing protocols should target exercise intensities ranging in-between 86-93% of heart rate maximum. © Georg Thieme Verlag KG Stuttgart · New York.

  11. And yet they act together: interpersonal perception modulates visuo-motor interference and mutual adjustments during a joint-grasping task.

    Science.gov (United States)

    Sacheli, Lucia Maria; Candidi, Matteo; Pavone, Enea Francesco; Tidoni, Emmanuele; Aglioti, Salvatore Maria

    2012-01-01

    Prediction of "when" a partner will act and "what" he is going to do is crucial in joint-action contexts. However, studies on face-to-face interactions in which two people have to mutually adjust their movements in time and space are lacking. Moreover, while studies on passive observation have shown that somato-motor simulative processes are disrupted when the observed actor is perceived as an out-group or unfair individual, the impact of interpersonal perception on joint-actions has never been directly addressed. Here we explored this issue by comparing the ability of pairs of participants who did or did not undergo an interpersonal perception manipulation procedure to synchronise their reach-to-grasp movements during: i) a guided interaction, requiring pure temporal reciprocal coordination, and ii) a free interaction, requiring both time and space adjustments. Behavioural results demonstrate that while in neutral situations free and guided interactions are equally challenging for participants, a negative interpersonal relationship improves performance in guided interactions at the expense of the free interactive ones. This was paralleled at the kinematic level by the absence of movement corrections and by low movement variability in these participants, indicating that partners cooperating within a negative interpersonal bond executed the cooperative task on their own, without reciprocally adapting to the partner's motor behaviour. Crucially, participants' performance in the free interaction improved in the manipulated group during the second experimental session while partners became interdependent as suggested by higher movement variability and by the appearance of interference between the self-executed actions and those observed in the partner. Our study expands current knowledge about on-line motor interactions by showing that visuo-motor interference effects, mutual motor adjustments and motor-learning mechanisms are influenced by social perception.

  12. And yet they act together: interpersonal perception modulates visuo-motor interference and mutual adjustments during a joint-grasping task.

    Directory of Open Access Journals (Sweden)

    Lucia Maria Sacheli

    Full Text Available Prediction of "when" a partner will act and "what" he is going to do is crucial in joint-action contexts. However, studies on face-to-face interactions in which two people have to mutually adjust their movements in time and space are lacking. Moreover, while studies on passive observation have shown that somato-motor simulative processes are disrupted when the observed actor is perceived as an out-group or unfair individual, the impact of interpersonal perception on joint-actions has never been directly addressed. Here we explored this issue by comparing the ability of pairs of participants who did or did not undergo an interpersonal perception manipulation procedure to synchronise their reach-to-grasp movements during: i a guided interaction, requiring pure temporal reciprocal coordination, and ii a free interaction, requiring both time and space adjustments. Behavioural results demonstrate that while in neutral situations free and guided interactions are equally challenging for participants, a negative interpersonal relationship improves performance in guided interactions at the expense of the free interactive ones. This was paralleled at the kinematic level by the absence of movement corrections and by low movement variability in these participants, indicating that partners cooperating within a negative interpersonal bond executed the cooperative task on their own, without reciprocally adapting to the partner's motor behaviour. Crucially, participants' performance in the free interaction improved in the manipulated group during the second experimental session while partners became interdependent as suggested by higher movement variability and by the appearance of interference between the self-executed actions and those observed in the partner. Our study expands current knowledge about on-line motor interactions by showing that visuo-motor interference effects, mutual motor adjustments and motor-learning mechanisms are influenced by social

  13. Improvement of Mental Imagery after Prism Exposure in Neglect: A Case Study

    Directory of Open Access Journals (Sweden)

    Gilles Rode

    1999-01-01

    Full Text Available Previous work has shown that various symptoms of unilateral neglect, including the pathological shift of the subjective midline to the right, may be improved by a short adaptation period to a prismatic shift of the visual field to the right. We report here the improvement of imagined neglect after prism exposure in a patient with a left unilateral neglect. Despite a strong neglect observed for mental images as well as for conventional tests, the mental evocation of left-sided information from an internal image of the map of France map was fully recovered following prism adaptation to the right. This improvement could not be explained by the alteration of visuomotor responses induced by the prism adaptation. Prism adaptation may therefore act not only on sensory-motor levels but also on a higher cognitive level of mental space representation and/or exploration.

  14. Adaptation of macrophages to exercise training improves innate immunity.

    Science.gov (United States)

    Kizaki, Takako; Takemasa, Tohru; Sakurai, Takuya; Izawa, Tetsuya; Hanawa, Tomoko; Kamiya, Shigeru; Haga, Shukoh; Imaizumi, Kazuhiko; Ohno, Hideki

    2008-07-18

    The effects of 3-week exercise training on the functions of peritoneal macrophages from BALB/c mice were investigated. Lipopolysaccharide (LPS)-stimulated nitric oxide (NO) and proinflammatory cytokine production in macrophages from trained mice was markedly higher than those from control mice. Meanwhile, exercise training decreased the steady state level of beta(2)-adrenergic receptor (beta(2)AR) mRNA in macrophages. Overexpression of beta(2)AR in the macrophage cell line RAW264 by transfecting with beta(2)AR cDNA suppressed NO synthase (NOS) II expression but dose not influenced proinflammatory cytokine expression. When expression of transfected beta(2)AR in RAWar cells was downregulated by a tetracycline repressor-regulated mammalian expression system, NOS II mRNA expression was significantly increased; this suggested that the changes in the beta(2)AR expression level in macrophages associated with exercise training play a role in the regulation of NO production following LPS stimulation. These findings indicate that exercise training improves macrophage innate immune function in a beta(2)AR-dependent and -independent manner.

  15. Neurodynamics of the prefrontal cortex during conditional visuomotor associations.

    Science.gov (United States)

    Loh, Marco; Pasupathy, Anitha; Miller, Earl K; Deco, Gustavo

    2008-03-01

    The prefrontal cortex is believed to be important for cognitive control, working memory, and learning. It is known to play an important role in the learning and execution of conditional visuomotor associations, a cognitive task in which stimuli have to be associated with actions by trial-and-error learning. In our modeling study, we sought to integrate several hypotheses on the function of the prefrontal cortex using a computational model, and compare the results to experimental data. We constructed a module of prefrontal cortex neurons exposed to two different inputs, which we envision to originate from the inferotemporal cortex and the basal ganglia. We found that working memory properties do not describe the dominant dynamics in the prefrontal cortex, but the activation seems to be transient, probably progressing along a pathway from sensory to motor areas. During the presentation of the cue, the dynamics of the prefrontal cortex is bistable, yielding a distinct activation for correct and error trails. We find that a linear change in network parameters relates to the changes in neural activity in consecutive correct trials during learning, which is important evidence for the underlying learning mechanisms.

  16. Testes visuomotores em crianças com estrabismo

    Directory of Open Access Journals (Sweden)

    Jorge Alberto F. Caldeira

    1970-09-01

    Full Text Available Em 43 crianças estrábicas nas quais foi determinado o quociente intelectual foram aplicados os testes visuomotores de Goldstein-Scheerer, Bender-Santucci, lateralidade e estereognosia. Os resultados foram comparados com os obtidos em 44 controles dos mesmos grupos etários e sócio-econômicamente semelhantes. Sugere-se o prosseguimento desta pesquisa com o estudo comparativo entre o teste de Goldstein-Scheerer e o "visual retention test" de Benton (1963 nos quais a análise do fator memória visual pode ser útil para averiguar dificuldades relacionadas com a prontidão para a alfabetização. Sugere-se, também, o estudo de um grupo de crianças em idade escolar com e sem perturbações da motilidade ocular extrínseca para avaliar a influência da escolaridade nos resultados dos testes.

  17. Visuomotor Integration and Executive Functioning Are Uniquely Linked to Chinese Word Reading and Writing in Kindergarten Children

    Science.gov (United States)

    Chung, Kevin Kien Hoa; Lam, Chun Bun; Cheung, Ka Chun

    2018-01-01

    This cross-sectional study examined the associations of visuomotor integration and executive functioning with Chinese word reading and writing in kindergarten children. A total of 369 Chinese children (mean age = 57.99 months; 55% of them were girls) from Hong Kong, China, completed tasks on visuomotor integration, executive functioning, and…

  18. Improved Adaptive Vibe and the Application for Segmentation of Complex Background

    Directory of Open Access Journals (Sweden)

    Le Chang

    2016-01-01

    Full Text Available To solve the problems that basic Vibe algorithm cannot effectively eliminate the influence of background noise, follower shadow, and ghost under complex background effectively, an adaptive threshold algorithm, AdaVibe, based on the framework of basic Vibe is proposed. Aiming at the shortage of the basic algorithm, this paper puts forward some improvement measures in threshold setting, shadow eliminating, and ghost suppression. Firstly, judgment threshold takes adjustment with the changes of background. Secondly, a fast eliminating ghost algorithm depending on adaptive threshold is introduced. Finally, follower shadow is detected and inhibited effectively through the gray properties and texture characteristics. Experiments show that the proposed AdaVibe algorithm works well in complex environment without affecting computing speed and has stronger robustness and better adaptability than the basic algorithm. Meanwhile, the ghost and follower shadow can be absorbed quickly as well. Therefore, the accuracy of target detection is effectively improved.

  19. Credit assignment in multiple goal embodied visuomotor behavior

    Directory of Open Access Journals (Sweden)

    Constantin A Rothkopf

    2010-11-01

    Full Text Available The intrinsic complexity of the brain can lead one to set aside issues related to its relationships with the body, but the field of embodied cognition emphasizes that understanding brain function at the system level requires one to address the role of the brain-body interface. It has only recently been appreciated that this interface performs huge amounts of computation that does not have to be repeated by the brain, and thus affords the brain great simplifications in its representations. In effect the brain’s abstract states can refer to coded representations of the world created by the body.But even if the brain can communicate with the world through abstractions, the severe speed limitations in its neural circuitry mean that vast amounts of indexing must be performed during development so that appropriate behavioral responses can be rapidly accessed. One way this could happen would be if the brain used a decomposition whereby behavioral primitives could be quickly accessed and combined. This realization motivates of our study of independent sensorimotor task solvers, which we call modules, in directing behavior.The issue we focus on herein is how an embodied agent can learn such individual visuomotor modules while pursuing multiple goals. The biologically plausible standard for module programming is that of reinforcement given during exploration of the environment. However this formulation contains a substantial issue when sensorimotor modules are used in combination: The credit for their overall performance must be divided amongst them. We show that this problem can be solved and that diverse task combinations are beneficial in learning and not a complication, as usually assumed. Our simulations show that fast algorithms are available that allot credit correctly and are insensitive to measurement noise.

  20. Testing multiple coordination constraints with a novel bimanual visuomotor task.

    Directory of Open Access Journals (Sweden)

    Helene M Sisti

    Full Text Available The acquisition of a new bimanual skill depends on several motor coordination constraints. To date, coordination constraints have often been tested relatively independently of one another, particularly with respect to isofrequency and multifrequency rhythms. Here, we used a new paradigm to test the interaction of multiple coordination constraints. Coordination constraints that were tested included temporal complexity, directionality, muscle grouping, and hand dominance. Twenty-two healthy young adults performed a bimanual dial rotation task that required left and right hand coordination to track a moving target on a computer monitor. Two groups were compared, either with or without four days of practice with augmented visual feedback. Four directional patterns were tested such that both hands moved either rightward (clockwise, leftward (counterclockwise, inward or outward relative to each other. Seven frequency ratios (3∶1, 2∶1, 3∶2, 1∶1, 2∶3. 1∶2, 1∶3 between the left and right hand were introduced. As expected, isofrequency patterns (1∶1 were performed more successfully than multifrequency patterns (non 1∶1. In addition, performance was more accurate when participants were required to move faster with the dominant right hand (1∶3, 1∶2 and 2∶3 than with the non-dominant left hand (3∶1, 2∶1, 3∶2. Interestingly, performance deteriorated as the relative angular velocity between the two hands increased, regardless of whether the required frequency ratio was an integer or non-integer. This contrasted with previous finger tapping research where the integer ratios generally led to less error than the non-integer ratios. We suggest that this is due to the different movement topologies that are required of each paradigm. Overall, we found that this visuomotor task was useful for testing the interaction of multiple coordination constraints as well as the release from these constraints with practice in the presence of

  1. Adaptive physical activity improves mobility function and quality of life in chronic hemiparesis.

    Science.gov (United States)

    Macko, Richard F; Benvenuti, Francesco; Stanhope, Steven; Macellari, Velio; Taviani, Antonia; Nesi, Barbara; Weinrich, Michael; Stuart, Mary

    2008-01-01

    This study investigated the effects of an adaptive physical activity (APA) program on mobility function and quality of life (QOL) in chronic stroke patients. Twenty subjects with chronic hemiparesis completed a 2-month, combined group, class-home exercise regimen that emphasized mobility training. APA improved Berg Balance Scale scores (35 +/- 2 vs 45 +/- 2, p = 0.001), 6-minute walk distances (114 +/- 15 vs 142 +/- 7 m, p APA (p APA has the potential to improve gait, balance, and basic but not instrumental activities of daily living profiles in individuals with chronic stroke. Improved depression and SIS scores suggest APA improves stroke-specific outcomes related to QOL.

  2. Astronomical image denoising by means of improved adaptive backtracking-based matching pursuit algorithm.

    Science.gov (United States)

    Liu, Qianshun; Bai, Jian; Yu, Feihong

    2014-11-10

    In an effort to improve compressive sensing and spare signal reconstruction by way of the backtracking-based adaptive orthogonal matching pursuit (BAOMP), a new sparse coding algorithm called improved adaptive backtracking-based OMP (ABOMP) is proposed in this study. Many aspects have been improved compared to the original BAOMP method, including replacing the fixed threshold with an adaptive one, adding residual feedback and support set verification, and others. Because of these ameliorations, the proposed algorithm can more precisely choose the atoms. By adding the adaptive step-size mechanism, it requires much less iteration and thus executes more efficiently. Additionally, a simple but effective contrast enhancement method is also adopted to further improve the denoising results and visual effect. By combining the IABOMP algorithm with the state-of-art dictionary learning algorithm K-SVD, the proposed algorithm achieves better denoising effects for astronomical images. Numerous experimental results show that the proposed algorithm performs successfully and effectively on Gaussian and Poisson noise removal.

  3. Changes in corticospinal drive to spinal motoneurones following visuo-motor skill learning in humans

    DEFF Research Database (Denmark)

    Perez, Monica A.; Jensen, Jesper Lundbye; Nielsen, Jens Bo

    2006-01-01

    . Coupling in the time (cumulant density function) and frequency domains (coherence) between EEG-EMG and EMG-EMG activity were calculated during tonic isometric dorsiflexion before and after 32 min of training a visuo-motor tracking task involving the ankle muscles or performing alternating dorsi......- and plantarflexion movements without visual feedback. A significant increase in EEG-EMG coherence around 15-35 Hz was observed following the visuo-motor skill session in nine subjects and in only one subject after the control task. Changes in coherence were specific to the trained muscle as coherence...

  4. An improved adaptive genetic algorithm for image segmentation and vision alignment used in microelectronic bonding

    OpenAIRE

    Wang, Fujun; Li, Junlan; Liu, Shiwei; Zhao, Xingyu; Zhang, Dawei; Tian, Yanling

    2014-01-01

    In order to improve the precision and efficiency of microelectronic bonding, this paper presents an improved adaptive genetic algorithm (IAGA) for the image segmentation and vision alignment of the solder joints in the microelectronic chips. The maximum between-cluster variance (OTSU) threshold segmentation method was adopted for the image segmentation of microchips, and the IAGA was introduced to the threshold segmentation considering the features of the images. The performance of the image ...

  5. Improving Ingredient Substitution using Formal Concept Analysis and Adaptation of Ingredient Quantities with Mixed Linear Optimization

    OpenAIRE

    Gaillard, Emmanuelle; Lieber, Jean; Nauer, Emmanuel

    2015-01-01

    International audience; This paper presents the participation of the Taaable team to the 2015 Computer Cooking Contest. The Taaable system addresses the mixology and the sandwich challenges. For the mixology challenge, the 2014 Taaable system was extended in two ways. First, a formal concept analysis approach is used to improve the ingredient substitution, which must take into account a limited set of available foods. Second, the adaptation of the ingredient quantities has also been improved ...

  6. Improving the Adaptability of Simulated Evolutionary Swarm Robots in Dynamically Changing Environments

    Science.gov (United States)

    Yao, Yao; Marchal, Kathleen; Van de Peer, Yves

    2014-01-01

    One of the important challenges in the field of evolutionary robotics is the development of systems that can adapt to a changing environment. However, the ability to adapt to unknown and fluctuating environments is not straightforward. Here, we explore the adaptive potential of simulated swarm robots that contain a genomic encoding of a bio-inspired gene regulatory network (GRN). An artificial genome is combined with a flexible agent-based system, representing the activated part of the regulatory network that transduces environmental cues into phenotypic behaviour. Using an artificial life simulation framework that mimics a dynamically changing environment, we show that separating the static from the conditionally active part of the network contributes to a better adaptive behaviour. Furthermore, in contrast with most hitherto developed ANN-based systems that need to re-optimize their complete controller network from scratch each time they are subjected to novel conditions, our system uses its genome to store GRNs whose performance was optimized under a particular environmental condition for a sufficiently long time. When subjected to a new environment, the previous condition-specific GRN might become inactivated, but remains present. This ability to store ‘good behaviour’ and to disconnect it from the novel rewiring that is essential under a new condition allows faster re-adaptation if any of the previously observed environmental conditions is reencountered. As we show here, applying these evolutionary-based principles leads to accelerated and improved adaptive evolution in a non-stable environment. PMID:24599485

  7. Improving the bearing fault diagnosis efficiency by the adaptive stochastic resonance in a new nonlinear system

    Science.gov (United States)

    Liu, Xiaole; Liu, Houguang; Yang, Jianhua; Litak, Grzegorz; Cheng, Gang; Han, Shuai

    2017-11-01

    It is a challenging task to detect the weak character signal in the noisy background. The stochastic resonance (SR) method has been wildly adopted recently because it can not only reduce the noise, but also enhance the weak feature information simultaneously. However, the traditional bistable model for SR is not perfect. So, this paper presents a new model with periodic potential to induce the adaptive SR. In the new model, based on the adaptive SR theory, the system parameters are simultaneously optimized by the improved artificial fish swarm algorithm. Meanwhile, the improved signal-to-noise ratio (ISNR) is set as the evaluation index. When the ISNR reaches a maximum, the output is optimal. In order to eliminate interference to obtain more useful information, the signals are preprocessed by Hilbert transform and High-pass filter before being input to the adaptive SR system. To verify the effectiveness of the proposed method, both numerical simulation and the vibration signal of the rolling element bearing from the lab experimental are adopted. Both of the results indicate that the adaptive SR model proposed shows better performance in weak character signals detection than the traditional adaptive SR in the bistable model. Meanwhile, the experimental signals with different working conditions are also processed by the new method. The results show that the method proposed could be more widely applied.

  8. Improving environmental and social targeting through adaptive management in Mexico's payments for hydrological services program.

    Science.gov (United States)

    Sims, Katharine R E; Alix-Garcia, Jennifer M; Shapiro-Garza, Elizabeth; Fine, Leah R; Radeloff, Volker C; Aronson, Glen; Castillo, Selene; Ramirez-Reyes, Carlos; Yañez-Pagans, Patricia

    2014-10-01

    Natural resource managers are often expected to achieve both environmental protection and economic development even when there are fundamental trade-offs between these goals. Adaptive management provides a theoretical structure for program administrators to balance social priorities in the presence of trade-offs and to improve conservation targeting. We used the case of Mexico's federal Payments for Hydrological Services program (PSAH) to illustrate the importance of adaptive management for improving program targeting. We documented adaptive elements of PSAH and corresponding changes in program eligibility and selection criteria. To evaluate whether these changes resulted in enrollment of lands of high environmental and social priority, we compared the environmental and social characteristics of the areas enrolled in the program with the characteristics of all forested areas in Mexico, all areas eligible for the program, and all areas submitted for application to the program. The program successfully enrolled areas of both high ecological and social priority, and over time, adaptive changes in the program's criteria for eligibility and selection led to increased enrollment of land scoring high on both dimensions. Three factors facilitated adaptive management in Mexico and are likely to be generally important for conservation managers: a supportive political environment, including financial backing and encouragement to experiment from the federal government; availability of relatively good social and environmental data; and active participation in the review process by stakeholders and outside evaluators. © 2014 Society for Conservation Biology.

  9. Does a torsion adapter improve functional mobility, pain, and fatigue in patients with transtibial amputation?

    Science.gov (United States)

    Segal, Ava D; Kracht, Rose; Klute, Glenn K

    2014-10-01

    Turning gait is an integral part of daily ambulation and likely poses a greater challenge for patients with transtibial amputation compared with walking a straight pathway. A torsion adapter is a prosthetic component that can increase transverse plane compliance of the prosthesis and decrease the torque applied to the residual limb, but whether this will improve patients' mobility, pain, and fatigue remains unknown. Does prescription of a torsion adapter translate to improvements in (1) functional mobility and (2) self-perceived pain and fatigue in moderately active patients with lower limb amputation? Ten unilateral transtibial amputees wore a torsion or rigid adapter in random order. Functional mobility was assessed through a field measurement using an activity monitor and through a laboratory measurement using a 6-minute walk test that included turns. The residual limb pain grade assessed self-perceived pain and the Multidimensional Fatigue Inventory assessed fatigue. We found relatively small functional differences for amputees wearing a torsion adapter versus a rigid adapter. Amputees wearing a torsion adapter tended to take more low- and medium-intensity steps per day (331 ± 365 and 437 ± 511 difference in steps; effect size = 0.44 and 0.17; confidence interval [CI], 70-592 and 71-802; p = 0.019 and 0.024, respectively). They also experienced less pain interference with activities (1.9 ± 1.7 change in score; effect size = 0.83; CI, 0.3-3.4; p = 0.026) when wearing a torsion adapter. However, these patients took a similar number of total steps per day, walked a comparable distance in 6 minutes, and reported similar residual limb pain and fatigue. For a moderately active group of amputees, the torsion adapter did not translate to substantial improvements in functional mobility and self-perceived pain and fatigue. The small increases in low- and medium-intensity activities with less pain interference when wearing a torsion adapter provides evidence to support

  10. An improved adaptive sampling and experiment design method for aerodynamic optimization

    Directory of Open Access Journals (Sweden)

    Huang Jiangtao

    2015-10-01

    Full Text Available Experiment design method is a key to construct a highly reliable surrogate model for numerical optimization in large-scale project. Within the method, the experimental design criterion directly affects the accuracy of the surrogate model and the optimization efficient. According to the shortcomings of the traditional experimental design, an improved adaptive sampling method is proposed in this paper. The surrogate model is firstly constructed by basic sparse samples. Then the supplementary sampling position is detected according to the specified criteria, which introduces the energy function and curvature sampling criteria based on radial basis function (RBF network. Sampling detection criteria considers both the uniformity of sample distribution and the description of hypersurface curvature so as to significantly improve the prediction accuracy of the surrogate model with much less samples. For the surrogate model constructed with sparse samples, the sample uniformity is an important factor to the interpolation accuracy in the initial stage of adaptive sampling and surrogate model training. Along with the improvement of uniformity, the curvature description of objective function surface gradually becomes more important. In consideration of these issues, crowdness enhance function and root mean square error (RMSE feedback function are introduced in C criterion expression. Thus, a new sampling method called RMSE and crowdness enhance (RCE adaptive sampling is established. The validity of RCE adaptive sampling method is studied through typical test function firstly and then the airfoil/wing aerodynamic optimization design problem, which has high-dimensional design space. The results show that RCE adaptive sampling method not only reduces the requirement for the number of samples, but also effectively improves the prediction accuracy of the surrogate model, which has a broad prospects for applications.

  11. A self-adaptive step Cuckoo search algorithm based on dimension by dimension improvement

    Directory of Open Access Journals (Sweden)

    Lu REN

    2015-10-01

    Full Text Available The choice of step length plays an important role in convergence speed and precision of Cuckoo search algorithm. In the paper, a self-adaptive step Cuckoo search algorithm based on dimensional improvement is provided. First, since the step in the original self-adaptive step Cuckoo search algorithm is not updated when the current position of the nest is in the optimal position, simple modification of the step is made for the update. Second, evaluation strategy based on dimension by dimension update is introduced to the modified self-adaptive step Cuckoo search algorithm. The experimental results show that the algorithm can balance the contradiction between the global convergence ability and the precision of optimization. Moreover, the proposed algorithm has better convergence speed.

  12. Moving forward with prisms: Sensory-motor adaptation improves gait initiation in Parkinson’s disease.

    Directory of Open Access Journals (Sweden)

    Janet Helen Bultitude

    2012-09-01

    Full Text Available It is postulated that the decreased walking speed; small, shuffling steps; and ‘freezing’ shown by patients with Parkinson’s disease could stem from an inability to tilt the body forward enough to provide sufficient forward propulsion. In two repeated-measures studies we examined whether adaptation to upward-shifting prisms, resulting in a downward after-effect, could improve gait initiation in healthy participants and patients with Parkinson’s disease. Faster forward stepping followed a brief (5 min exposure period for patients, and a longer (20 min exposure period for age-matched controls. Backward stepping was unchanged, and adaptation to downward-shifting prisms with control participants showed no effect on forward or backward stepping. These results suggest that adaptation of arm proprioception in the vertical plane may generalise to anterior-posterior postural control, presenting new possibilities for the treatment of gait disturbance in basal ganglia disorders.

  13. Autonomous emergency braking systems adapted to snowy road conditions improve drivers' perceived safety and trust.

    Science.gov (United States)

    Koglbauer, Ioana; Holzinger, Jürgen; Eichberger, Arno; Lex, Cornelia

    2017-12-11

    This study investigated drivers' evaluation of a conventional autonomous emergency braking (AEB) system on high and reduced tire-road friction and compared these results to those of an AEB system adaptive to the reduced tire-road friction by earlier braking. Current automated systems such as the AEB do not adapt the vehicle control strategy to the road friction; for example, on snowy roads. Because winter precipitation is associated with a 19% increase in traffic crashes and a 13% increase in injuries compared to dry conditions, the potential of conventional AEB to prevent collisions could be significantly improved by including friction in the control algorithm. Whereas adaption is not legally required for a conventional AEB system, higher automated functions will have to adapt to the current tire-road friction because human drivers will not be required to monitor the driving environment at all times. For automated driving functions to be used, high levels of perceived safety and trust of occupants have to be reached with new systems. The application case of an AEB is used to investigate drivers' evaluation depending on the road condition in order to gain knowledge for the design of future driving functions. In a driving simulator, the conventional, nonadaptive AEB was evaluated on dry roads with high friction (μ = 1) and on snowy roads with reduced friction (μ = 0.3). In addition, an AEB system adapted to road friction was designed for this study and compared with the conventional AEB on snowy roads with reduced friction. Ninety-six drivers (48 males, 48 females) assigned to 5 age groups (20-29, 30-39, 40-49, 50-59, and 60-75 years) drove with AEB in the simulator. The drivers observed and evaluated the AEB's braking actions in response to an imminent rear-end collision at an intersection. The results show that drivers' safety and trust in the conventional AEB were significantly lower on snowy roads, and the nonadaptive autonomous braking strategy was

  14. Locomotor Adaptation Improves Balance Control, Multitasking Ability and Reduces the Metabolic Cost of Postural Instability

    Science.gov (United States)

    Bloomberg, J. J.; Peters, B. T.; Mulavara, A. P.; Brady, R. A.; Batson, C. D.; Miller, C. A.; Ploutz-Snyder, R. J.; Guined, J. R.; Buxton, R. E.; Cohen, H. S.

    2011-01-01

    During exploration-class missions, sensorimotor disturbances may lead to disruption in the ability to ambulate and perform functional tasks during the initial introduction to a novel gravitational environment following a landing on a planetary surface. The overall goal of our current project is to develop a sensorimotor adaptability training program to facilitate rapid adaptation to these environments. We have developed a unique training system comprised of a treadmill placed on a motion-base facing a virtual visual scene. It provides an unstable walking surface combined with incongruent visual flow designed to enhance sensorimotor adaptability. Greater metabolic cost incurred during balance instability means more physical work is required during adaptation to new environments possibly affecting crewmembers? ability to perform mission critical tasks during early surface operations on planetary expeditions. The goal of this study was to characterize adaptation to a discordant sensory challenge across a number of performance modalities including locomotor stability, multi-tasking ability and metabolic cost. METHODS: Subjects (n=15) walked (4.0 km/h) on a treadmill for an 8 -minute baseline walking period followed by 20-minutes of walking (4.0 km/h) with support surface motion (0.3 Hz, sinusoidal lateral motion, peak amplitude 25.4 cm) provided by the treadmill/motion-base system. Stride frequency and auditory reaction time were collected as measures of locomotor stability and multi-tasking ability, respectively. Metabolic data (VO2) were collected via a portable metabolic gas analysis system. RESULTS: At the onset of lateral support surface motion, subj ects walking on our treadmill showed an increase in stride frequency and auditory reaction time indicating initial balance and multi-tasking disturbances. During the 20-minute adaptation period, balance control and multi-tasking performance improved. Similarly, throughout the 20-minute adaptation period, VO2 gradually

  15. Coping capacities for improving adaptation pathways for flood protection in Can Tho, Vietnam

    Science.gov (United States)

    Pathirana, A.; Radhakrishnan, M.; Quan, N. H.; Gersonius, B.; Ashley, R.; Zevenbergen, C.

    2016-12-01

    Studying the evolution of coping and adaptation capacities is a prerequisite for preparing an effective flood management plan for the future, especially in the dynamic and fast changing cities of developing countries. The objectives, requirements, targets, design and performance of flood protection measures will have to be determined after taking into account, or in conjunction with, the coping capacities. A methodology is presented based on adaptation pathways to account for coping capacities and to assess the effect on flood protection measures. The adaptation pathways method determines the point of failure of a particular strategy based on the change in an external driver, a point in time or a socio economic situation where / at which the strategy can no longer meet its objective. Pathways arrived at based on this methodology reflect future reality by considering changing engineering standards along with future uncertainties, risk taking abilities and adaptation capacities. This pathways based methodology determines the Adaptation tipping points (ATP), `time of occurrence of ATP' of flood protection measures after accounting for coping capacities, evaluates the measures and then provides the means to determine the adaptation pathways. Application of this methodology for flood protection measures in Can Tho city in the Mekong delta reveals the effect of coping capacity on the usefulness of flood protection measures and the delay in occurrence of tipping points. Consideration of coping capacity in the system owing to elevated property floor levels lead to the postponement of tipping points and improved the adaptation pathways comprising flood protection measures such as dikes. This information is useful to decision makers for planning and phasing of investments in flood protection.

  16. Improving GPU-accelerated adaptive IDW interpolation algorithm using fast kNN search.

    Science.gov (United States)

    Mei, Gang; Xu, Nengxiong; Xu, Liangliang

    2016-01-01

    This paper presents an efficient parallel Adaptive Inverse Distance Weighting (AIDW) interpolation algorithm on modern Graphics Processing Unit (GPU). The presented algorithm is an improvement of our previous GPU-accelerated AIDW algorithm by adopting fast k-nearest neighbors (kNN) search. In AIDW, it needs to find several nearest neighboring data points for each interpolated point to adaptively determine the power parameter; and then the desired prediction value of the interpolated point is obtained by weighted interpolating using the power parameter. In this work, we develop a fast kNN search approach based on the space-partitioning data structure, even grid, to improve the previous GPU-accelerated AIDW algorithm. The improved algorithm is composed of the stages of kNN search and weighted interpolating. To evaluate the performance of the improved algorithm, we perform five groups of experimental tests. The experimental results indicate: (1) the improved algorithm can achieve a speedup of up to 1017 over the corresponding serial algorithm; (2) the improved algorithm is at least two times faster than our previous GPU-accelerated AIDW algorithm; and (3) the utilization of fast kNN search can significantly improve the computational efficiency of the entire GPU-accelerated AIDW algorithm.

  17. Visuospatial and visuomotor deficits in preterm children : The involvement of cerebellar dysfunctioning

    NARCIS (Netherlands)

    Van Braeckel, Koenraad N. J. A.; Taylor, H. Gerry

    2013-01-01

    One of the more consistent findings in follow-up studies of preterm children is a deficit in visuospatial and visuomotor skills. Impairment of the dorsal visual stream and basal ganglia damage have been hypothesized to underlie this deficit. However, given recent findings of impaired cerebellar

  18. Visuomotor Tracking Abilities of Speakers with Apraxia of Speech or Conduction Aphasia

    Science.gov (United States)

    Robin, Donald A.; Jacks, Adam; Hageman, Carlin; Clark, Heather M.; Woodworth, George

    2008-01-01

    This investigation examined the visuomotor tracking abilities of persons with apraxia of speech (AOS) or conduction aphasia (CA). In addition, tracking performance was correlated with perceptual judgments of speech accuracy. Five individuals with AOS and four with CA served as participants, as well as an equal number of healthy controls matched by…

  19. Dual-Tasking Alleviated Sleep Deprivation Disruption in Visuomotor Tracking: An fMRI Study

    Science.gov (United States)

    Gazes, Yunglin; Rakitin, Brian C.; Steffener, Jason; Habeck, Christian; Butterfield, Brady; Basner, Robert C.; Ghez, Claude; Stern, Yaakov

    2012-01-01

    Effects of dual-responding on tracking performance after 49-h of sleep deprivation (SD) were evaluated behaviorally and with functional magnetic resonance imaging (fMRI). Continuous visuomotor tracking was performed simultaneously with an intermittent color-matching visual detection task in which a pair of color-matched stimuli constituted a…

  20. Performance of a visuomotor walking task in an augmented reality training setting

    NARCIS (Netherlands)

    Haarman, Juliet A.M.; Choi, Julia T.; Buurke, Jaap H.; Rietman, Johan S.; Reenalda, Jasper

    2017-01-01

    Visual cues can be used to train walking patterns. Here, we studied the performance and learning capacities of healthy subjects executing a high-precision visuomotor walking task, in an augmented reality training set-up. A beamer was used to project visual stepping targets on the walking surface of

  1. Learning-related fMRI activation associated with a rotational visuo-motor transformation.

    Science.gov (United States)

    Graydon, Francis X; Friston, Karl J; Thomas, Christopher G; Brooks, Vernon B; Menon, Ravi S

    2005-03-01

    The unique ability to learn transformed or altered visuo-motor relationships during motor learning (visuo-motor transformation learning) has engaged researchers for over a century. Compared to other forms of motor learning (e.g., sequence learning), little is known about plasticity in the cortical and/or subcortical systems involved. We used fMRI to isolate region-specific activation changes during the learning of a visuo-motor (joystick) task under a simple transformation (90 degree rotation of visual feedback). Distributed brain systems were engaged in the learning process. In particular, we found evidence of a learning-dependent transition from early activation of the posterior parietal cortex to later distributed cortico-subcortical-cerebellar responses (in the temporal and occipital cortices, basal ganglia, cerebellum and thalamus). The role of the posterior parietal cortex may relate specifically to the acquisition of the transformation, while that of the fusiform and superior temporal gyri may reflect higher level visual and visuo-spatial processing underlying consolidation. Learning-related increases in cerebellar responses are consistent with its proposed role in the acquisition of internal models of the motor apparatus. These learning-related changes suggest a role for interacting neural systems involving the co-operation of cortico-cortico, cortico-cerebellar and cortico-basal ganglia loops during visuo-motor transformation learning.

  2. Evidence of enhancement of spatial attention during inhibition of a visuo-motor response

    NARCIS (Netherlands)

    Maguire, RP; Broerse, A; de Jong, BM; Cornelissen, FW; Meiners, LC; Leenders, KL; den Boer, JA

    2003-01-01

    A visuo-motor task was used as the setting for a study into inhibition in six healthy volunteers using fMRI. The task involved responding to colored stimuli, which appeared at random positions in the left and right visual field, with the corresponding hand. The volunteers were asked to respond to

  3. Improving the response of accelerometers for automotive applications by using LMS adaptive filters: Part II.

    Science.gov (United States)

    Hernandez, Wilmar; de Vicente, Jesús; Sergiyenko, Oleg Y; Fernández, Eduardo

    2010-01-01

    In this paper, the fast least-mean-squares (LMS) algorithm was used to both eliminate noise corrupting the important information coming from a piezoresisitive accelerometer for automotive applications, and improve the convergence rate of the filtering process based on the conventional LMS algorithm. The response of the accelerometer under test was corrupted by process and measurement noise, and the signal processing stage was carried out by using both conventional filtering, which was already shown in a previous paper, and optimal adaptive filtering. The adaptive filtering process relied on the LMS adaptive filtering family, which has shown to have very good convergence and robustness properties, and here a comparative analysis between the results of the application of the conventional LMS algorithm and the fast LMS algorithm to solve a real-life filtering problem was carried out. In short, in this paper the piezoresistive accelerometer was tested for a multi-frequency acceleration excitation. Due to the kind of test conducted in this paper, the use of conventional filtering was discarded and the choice of one adaptive filter over the other was based on the signal-to-noise ratio improvement and the convergence rate.

  4. Improving the Response of Accelerometers for Automotive Applications by Using LMS Adaptive Filters: Part II

    Directory of Open Access Journals (Sweden)

    Eduardo Fernández

    2010-01-01

    Full Text Available In this paper, the fast least-mean-squares (LMS algorithm was used to both eliminate noise corrupting the important information coming from a piezoresisitive accelerometer for automotive applications, and improve the convergence rate of the filtering process based on the conventional LMS algorithm. The response of the accelerometer under test was corrupted by process and measurement noise, and the signal processing stage was carried out by using both conventional filtering, which was already shown in a previous paper, and optimal adaptive filtering. The adaptive filtering process relied on the LMS adaptive filtering family, which has shown to have very good convergence and robustness properties, and here a comparative analysis between the results of the application of the conventional LMS algorithm and the fast LMS algorithm to solve a real-life filtering problem was carried out. In short, in this paper the piezoresistive accelerometer was tested for a multi-frequency acceleration excitation. Due to the kind of test conducted in this paper, the use of conventional filtering was discarded and the choice of one adaptive filter over the other was based on the signal-to-noise ratio improvement and the convergence rate.

  5. Adaptive slab laser beam quality improvement using a weighted least-squares reconstruction algorithm.

    Science.gov (United States)

    Chen, Shanqiu; Dong, LiZhi; Chen, XiaoJun; Tan, Yi; Liu, Wenjin; Wang, Shuai; Yang, Ping; Xu, Bing; Ye, YuTang

    2016-04-10

    Adaptive optics is an important technology for improving beam quality in solid-state slab lasers. However, there are uncorrectable aberrations in partial areas of the beam. In the criterion of the conventional least-squares reconstruction method, it makes the zones with small aberrations nonsensitive and hinders this zone from being further corrected. In this paper, a weighted least-squares reconstruction method is proposed to improve the relative sensitivity of zones with small aberrations and to further improve beam quality. Relatively small weights are applied to the zones with large residual aberrations. Comparisons of results show that peak intensity in the far field improved from 1242 analog digital units (ADU) to 2248 ADU, and beam quality β improved from 2.5 to 2.0. This indicates the weighted least-squares method has better performance than the least-squares reconstruction method when there are large zonal uncorrectable aberrations in the slab laser system.

  6. Improving Sensorimotor Adaptation Following Long Duration Space Flight by Enhancing Vestibular Information Transfer

    Science.gov (United States)

    Mulavara, A. P.; Kofman, I. S.; De Dios, Y. E; Galvan, R.; Goel, R.; Miller, C.; Peters, B.; Cohen, H. S.; Jeevarajan, J.; Reschke, M.; hide

    2014-01-01

    Crewmember adapted to the microgravity state may need to egress the vehicle within a few minutes for safety and operational reasons after gravitational transitions. The transition from one sensorimotor state to another consists of two main mechanisms: strategic and plastic-adaptive and have been demonstrated in astronauts returning after long duration space flight. Strategic modifications represent "early adaptation" - immediate and transitory changes in control that are employed to deal with short-term changes in the environment. If these modifications are prolonged then plastic-adaptive changes are evoked that modify central nervous system function, automating new behavioral responses. More importantly, this longer term adaptive recovery mechanism was significantly associated with their strategic ability to recover on the first day after return to Earth G. We are developing a method based on stochastic resonance to enhance information transfer by improving the brain's ability to detect vestibular signals (Vestibular Stochastic Resonance, VSR) especially when combined with balance training exercises such as sensorimotor adaptability (SA) training for rapid improvement in functional skill, for standing and mobility. This countermeasure to improve detection of vestibular signals is a stimulus delivery system that is wearable/portable providing low imperceptible levels of white noise based binaural bipolar electrical stimulation of the vestibular system (stochastic vestibular stimulation). To determine efficacy of vestibular stimulation on physiological and perceptual responses during otolith-canal conflicts and dynamic perturbations we have conducted a series of studies: We have shown that imperceptible binaural bipolar electrical stimulation of the vestibular system across the mastoids enhances balance performance in the mediolateral (ML) plane while standing on an unstable surface. We have followed up on the previous study showing VSR stimulation improved balance

  7. Assessment of the conservation measures partnership's effort to improve conservation outcomes through adaptive management.

    Science.gov (United States)

    Redford, Kent H; Hulvey, Kristin B; Williamson, Matthew; Schwartz, Mark W

    2018-01-03

    Conservation practice has demonstrated an increasing desire for accountability of actions, particularly with respect to effectiveness, efficiency, and impact to specified objectives. This has been accompanied by increased attention to achieving adaptive management. In 2003 practitioners representing several prominent conservation non-governmental organizations (NGO's) launched a community of practice called the Conservation Measures Partnership (CMP). This organization has worked to establish standards of conservation practice to improve accountability of conservation actions through adaptive management. The focal organizing entity for the CMP has been the Open Standards for the Practice of Conservation (OS). We present results of an evaluation, using an online survey and personal interviews, of the first decade of CMP and the OS. We find that the CMP, has garnered a positive reputation among the leading scientists across conservation NGO's and succeeded at developing a large user base of the OS. However, the CMP has not fully achieved its goal of making the OS standard operating procedure for the large NGO's. This lack of institutionalization is attributable to multiple causes, including an increase in the number of competing decision support frameworks and challenges achieving full cycle adaptive management. We find that users strongly feel that the OS fosters better conservation practice and highly value the OS for improving their practice. A primary objective of the OS is to assist practitioners to achieve full cycle adaptive management in order to better integrate learning into improving the effectiveness and efficiency of actions. However, we find that most practitioners have not yet achieved cycle completion for their projects. We summarize recommendations for improving effectiveness of the CMP, OS, and generally for conservation practice. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  8. Research on Improved Adaptive Control for Static Synchronous Compensator in Power System

    Directory of Open Access Journals (Sweden)

    Chao Zhang

    2015-01-01

    Full Text Available This paper deals with the problems of “explosion of term,” uncertain parameter in static synchronous compensator (STATCOM system with nonlinear time-delay. An improved adaptive controller is proposed to enhance the transient stability of system states and reduce computational complexity of STATCOM control system. In contrast to backstepping control scheme in high order systems, the problem of “explosion of term” is avoided by designing dynamic surface controller. The low pass filter is included to allow a design where the model is not differentiated and thus has prevented the mathematical complexities effectively. In addition, unlike the traditional adaptive control schemes, the certainty equivalence principle is not required for estimating the uncertain parameter by system immersion and manifold invariant (I&I adaptive control. A smooth function is added to ensure that the estimation error converges to zero in finite time. The effectiveness of the proposed controller is verified by the simulations. Compared with adaptive backstepping and proportion integration differentiation (PID, the oscillation amplitudes of transient response are reduced by nearly half, and the time of reaching steady state is shortened by at least 11%.

  9. Improving Early Adaptation Following Long Duration Spaceflight by Enhancing Vestibular Information

    Science.gov (United States)

    Mulavara, Ajitkumar; Kofman, Igor; DeDios, Yiri E.; Galvan, Raquel; Miller, Chris; Peters, Brian; Cohen, Helen; Jeevarajan, Jerome; Reschke, Millard; Wood, Scott; hide

    2014-01-01

    Crewmember adapted to the microgravity state may need to egress the vehicle within a few minutes for safety and operational reasons after g-transitions. The transition from one sensorimotor state to another consists of two main mechanisms: strategic and plastic-adaptive and have been demonstrated in astronauts returning after long duration space flight. Strategic modifications represent "early adaptation" -immediate and transitory changes in control that are employed to deal with short-term changes in the environment. If these modifications are prolonged then plastic-adaptive changes are evoked that modify central nervous system function, automating new behavioral responses. More importantly, this longer term adaptive recovery mechanism was significantly associated with their strategic ability to recover on the first day after return to Earth G. We are developing a method based on stochastic resonance (SR) to enhance information transfer by improving the brain's ability to detect vestibular signals especially when combined with balance training exercises for rapid improvement in functional skill, for standing and mobility. The countermeasure to improve post-flight balance and locomotor disturbances is a stimulus delivery system that is wearable/portable providing low imperceptible levels of white noise based binaural bipolar electrical stimulation of the vestibular system (stochastic vestibular stimulation, SVS). The techniques for improving signal detection using SVS may thus provide additional information to improve such strategic abilities and thus help in significantly reducing the number of days required to recover functional performance to preflight levels after long duration space flight. We have conducted a series of studies to document the efficacy of SVS stimulation on balance/locomotion tasks on unstable surfaces and motion tracking tasks during intra-vestibular system conflicts. In an initial study, we showed that SVS improved overall balance

  10. Adaptive optics in spinning disk microscopy: improved contrast and brightness by a simple and fast method.

    Science.gov (United States)

    Fraisier, V; Clouvel, G; Jasaitis, A; Dimitrov, A; Piolot, T; Salamero, J

    2015-09-01

    Multiconfocal microscopy gives a good compromise between fast imaging and reasonable resolution. However, the low intensity of live fluorescent emitters is a major limitation to this technique. Aberrations induced by the optical setup, especially the mismatch of the refractive index and the biological sample itself, distort the point spread function and further reduce the amount of detected photons. Altogether, this leads to impaired image quality, preventing accurate analysis of molecular processes in biological samples and imaging deep in the sample. The amount of detected fluorescence can be improved with adaptive optics. Here, we used a compact adaptive optics module (adaptive optics box for sectioning optical microscopy), which was specifically designed for spinning disk confocal microscopy. The module overcomes undesired anomalies by correcting for most of the aberrations in confocal imaging. Existing aberration detection methods require prior illumination, which bleaches the sample. To avoid multiple exposures of the sample, we established an experimental model describing the depth dependence of major aberrations. This model allows us to correct for those aberrations when performing a z-stack, gradually increasing the amplitude of the correction with depth. It does not require illumination of the sample for aberration detection, thus minimizing photobleaching and phototoxicity. With this model, we improved both signal-to-background ratio and image contrast. Here, we present comparative studies on a variety of biological samples. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

  11. Pre-Sleep Protein Ingestion to Improve the Skeletal Muscle Adaptive Response to Exercise Training.

    Science.gov (United States)

    Trommelen, Jorn; van Loon, Luc J C

    2016-11-28

    Protein ingestion following resistance-type exercise stimulates muscle protein synthesis rates, and enhances the skeletal muscle adaptive response to prolonged resistance-type exercise training. As the adaptive response to a single bout of resistance exercise extends well beyond the first couple of hours of post-exercise recovery, recent studies have begun to investigate the impact of the timing and distribution of protein ingestion during more prolonged recovery periods. Recent work has shown that overnight muscle protein synthesis rates are restricted by the level of amino acid availability. Protein ingested prior to sleep is effectively digested and absorbed, and thereby stimulates muscle protein synthesis rates during overnight recovery. When applied during a prolonged period of resistance-type exercise training, protein supplementation prior to sleep can further augment gains in muscle mass and strength. Recent studies investigating the impact of pre-sleep protein ingestion suggest that at least 40 g of protein is required to display a robust increase in muscle protein synthesis rates throughout overnight sleep. Furthermore, prior exercise allows more of the pre-sleep protein-derived amino acids to be utilized for de novo muscle protein synthesis during sleep. In short, pre-sleep protein ingestion represents an effective dietary strategy to improve overnight muscle protein synthesis, thereby improving the skeletal muscle adaptive response to exercise training.

  12. Computing Adaptive Feature Weights with PSO to Improve Android Malware Detection

    Directory of Open Access Journals (Sweden)

    Yanping Xu

    2017-01-01

    Full Text Available Android malware detection is a complex and crucial issue. In this paper, we propose a malware detection model using a support vector machine (SVM method based on feature weights that are computed by information gain (IG and particle swarm optimization (PSO algorithms. The IG weights are evaluated based on the relevance between features and class labels, and the PSO weights are adaptively calculated to result in the best fitness (the performance of the SVM classification model. Moreover, to overcome the defects of basic PSO, we propose a new adaptive inertia weight method called fitness-based and chaotic adaptive inertia weight-PSO (FCAIW-PSO that improves on basic PSO and is based on the fitness and a chaotic term. The goal is to assign suitable weights to the features to ensure the best Android malware detection performance. The results of experiments indicate that the IG weights and PSO weights both improve the performance of SVM and that the performance of the PSO weights is better than that of the IG weights.

  13. Compound faults detection of rotating machinery using improved adaptive redundant lifting multiwavelet

    Science.gov (United States)

    Chen, Jinglong; Zi, Yanyang; He, Zhengjia; Yuan, Jing

    2013-07-01

    Due to the character of diversity and complexity, the compound faults detection of rotating machinery under non-stationary operation turns into a challenging task. Multiwavelet with two or more base functions and many excellent properties provides a possibility to detect and extract all the features of compound faults at one time. However, the fixed basis functions independent of the vibration signal may decrease the accuracy of fault detection. Moreover, the decomposition result of discrete multiwavelet transform does not possess time invariance, which is harmful to extract the feature of periodical impulses. To overcome these deficiencies, based on the Hermite splines interpolation, taking the minimum envelope spectrum entropy as the optimization objective, adaptive redundant lifting multiwavelet is developed. Additionally, in order to eliminate error propagation of decomposition results, adaptive redundant lifting multiwavelet is improved by adding the normalization factors. As an effective method, Hilbert transform demodulation analysis is used to extract the fault feature from the high frequency modulation signal. The proposed method incorporating improved adaptive redundant lifting multiwavelet (IARLM) with Hilbert transform demodulation analysis is applied to compound faults detection for the simulation experiment, rolling element bearing test bench and traveling unit of electric locomotive. Compared with some other fault detection methods, the results show the superior effectiveness and reliability on the compound faults detection.

  14. SU-E-I-38: Improved Metal Artifact Correction Using Adaptive Dual Energy Calibration

    Energy Technology Data Exchange (ETDEWEB)

    Dong, X; Elder, E; Roper, J; Dhabaan, A [Winship Cancer Institute of Emory University (United States)

    2015-06-15

    Purpose: The empirical dual energy calibration (EDEC) method corrects for beam-hardening artifacts, but shows limited performance on metal artifact correction. In this work, we propose an adaptive dual energy calibration (ADEC) method to correct for metal artifacts. Methods: The empirical dual energy calibration (EDEC) method corrects for beam-hardening artifacts, but shows limited performance on metal artifact correction. In this work, we propose an adaptive dual energy calibration (ADEC) method to correct for metal artifacts. Results: Highly attenuating copper rods cause severe streaking artifacts on standard CT images. EDEC improves the image quality, but cannot eliminate the streaking artifacts. Compared to EDEC, the proposed ADEC method further reduces the streaking resulting from metallic inserts and beam-hardening effects and obtains material decomposition images with significantly improved accuracy. Conclusion: We propose an adaptive dual energy calibration method to correct for metal artifacts. ADEC is evaluated with the Shepp-Logan phantom, and shows superior metal artifact correction performance. In the future, we will further evaluate the performance of the proposed method with phantom and patient data.

  15. Pre-Sleep Protein Ingestion to Improve the Skeletal Muscle Adaptive Response to Exercise Training

    Directory of Open Access Journals (Sweden)

    Jorn Trommelen

    2016-11-01

    Full Text Available Protein ingestion following resistance-type exercise stimulates muscle protein synthesis rates, and enhances the skeletal muscle adaptive response to prolonged resistance-type exercise training. As the adaptive response to a single bout of resistance exercise extends well beyond the first couple of hours of post-exercise recovery, recent studies have begun to investigate the impact of the timing and distribution of protein ingestion during more prolonged recovery periods. Recent work has shown that overnight muscle protein synthesis rates are restricted by the level of amino acid availability. Protein ingested prior to sleep is effectively digested and absorbed, and thereby stimulates muscle protein synthesis rates during overnight recovery. When applied during a prolonged period of resistance-type exercise training, protein supplementation prior to sleep can further augment gains in muscle mass and strength. Recent studies investigating the impact of pre-sleep protein ingestion suggest that at least 40 g of protein is required to display a robust increase in muscle protein synthesis rates throughout overnight sleep. Furthermore, prior exercise allows more of the pre-sleep protein-derived amino acids to be utilized for de novo muscle protein synthesis during sleep. In short, pre-sleep protein ingestion represents an effective dietary strategy to improve overnight muscle protein synthesis, thereby improving the skeletal muscle adaptive response to exercise training.

  16. Stable adaptive PI control for permanent magnet synchronous motor drive based on improved JITL technique.

    Science.gov (United States)

    Zheng, Shiqi; Tang, Xiaoqi; Song, Bao; Lu, Shaowu; Ye, Bosheng

    2013-07-01

    In this paper, a stable adaptive PI control strategy based on the improved just-in-time learning (IJITL) technique is proposed for permanent magnet synchronous motor (PMSM) drive. Firstly, the traditional JITL technique is improved. The new IJITL technique has less computational burden and is more suitable for online identification of the PMSM drive system which is highly real-time compared to traditional JITL. In this way, the PMSM drive system is identified by IJITL technique, which provides information to an adaptive PI controller. Secondly, the adaptive PI controller is designed in discrete time domain which is composed of a PI controller and a supervisory controller. The PI controller is capable of automatically online tuning the control gains based on the gradient descent method and the supervisory controller is developed to eliminate the effect of the approximation error introduced by the PI controller upon the system stability in the Lyapunov sense. Finally, experimental results on the PMSM drive system show accurate identification and favorable tracking performance. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

  17. An improved adaptive weighting function method for State Estimation in Power Systems with VSC-MTDC

    Science.gov (United States)

    Zhao, Kun; Yang, Xiaonan; Lang, Yansheng; Song, Xuri; Wang, Minkun; Luo, Yadi; Wu, Lingyun; Liu, Peng

    2017-04-01

    This paper presents an effective approach for state estimation in power systems that include multi-terminal voltage source converter based high voltage direct current (VSC-MTDC), called improved adaptive weighting function method. The proposed approach is simplified in which the VSC-MTDC system is solved followed by the AC system. Because the new state estimation method only changes the weight and keeps the matrix dimension unchanged. Accurate and fast convergence of AC/DC system can be realized by adaptive weight function method. This method also provides the technical support for the simulation analysis and accurate regulation of AC/DC system. Both the oretical analysis and numerical tests verify practicability, validity and convergence of new method.

  18. Improving preschooler conduct adaptation by using a social learning program based on motion games

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    Zsuzsa Szilárda

    2017-03-01

    Full Text Available Being aware of the changes which occur under the influence of environmental conditions, education, culture and social roles upon the child is indispensable with a view to build up a conduct adapted to the social environment. For any preschooler child, entering kindergarten is an important social event and getting adapted to the new situation is not easy. Broadening the relational framework with objects, other individuals, with one’s own self, results in disciplining preschooler conducts and increasing the number of socially desirable conducts. Relying upon the above statements, this study is aimed at working out a social learning programme made up of motion games involving socialization/cooperation elements intended for inducing amelioration in terms of the child’s conduct during the process of adaptation to the kindergarten environment. The experiment was conducted using a sample of “little group” preschoolers (children 3-4 years of age. As research methods, the following have been used: studying the reference literature, the method of pedagogical observation, the method of experiment and the method of playing. Further to the practical application of the programme worked out with a view to enhance the adaptation conduct in the said subjects, the experimental group proved to have undergone a significant positive evolution and each subject showed improvements considering the conduct of adaptation to kindergarten conditions, as highlighted by the change i.e. higher values in terms of the individual scores achieved at the final test. Preschool education is meant to provide all possible ways and means to enable any child’s integration into groups of children of a peer age, to develop sociability in children and to create favorable conditions for building out inter-children networks.

  19. Waiting for a hand: saccadic reaction time increases in proportion to hand reaction time when reaching under a visuomotor reversal

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    Irene eArmstrong

    2013-07-01

    Full Text Available Although eye movement onset typically precedes hand movement onset when reaching to targets presented in peripheral vision, arm motor commands appear to be issued at around the same time, and possibly in advance, of eye motor commands. A fundamental question, therefore, is whether eye movement initiation is linked or yoked to hand movement. We addressed this issue by having participants reach to targets after adapting to a visuomotor reversal (or 180° rotation between the position of the unseen hand and the position of a cursor controlled by the hand. We asked whether this reversal, which we expected to increase hand reaction time (HRT, would also increase saccadic reaction time (SRT. As predicted, when moving the cursor to targets under the reversal, HRT increased in all participants. SRT also increased in all but one participant, even though the task for the eyes – shifting gaze to the target – was unaltered by the reversal of hand position feedback. Moreover, the effects of the reversal on SRT and HRT were positively correlated across participants; those who exhibited the greatest increases in HRT also showed the greatest increases in SRT. These results indicate that the mechanisms underlying the initiation of eye and hand movements are linked. In particular, the results suggest that the initiation of an eye movement to a manual target depends, at least in part, on the specification of hand movement.

  20. Method of Improved Fuzzy Contrast Combined Adaptive Threshold in NSCT for Medical Image Enhancement

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    Fei Zhou

    2017-01-01

    Full Text Available Noises and artifacts are introduced to medical images due to acquisition techniques and systems. This interference leads to low contrast and distortion in images, which not only impacts the effectiveness of the medical image but also seriously affects the clinical diagnoses. This paper proposes an algorithm for medical image enhancement based on the nonsubsampled contourlet transform (NSCT, which combines adaptive threshold and an improved fuzzy set. First, the original image is decomposed into the NSCT domain with a low-frequency subband and several high-frequency subbands. Then, a linear transformation is adopted for the coefficients of the low-frequency component. An adaptive threshold method is used for the removal of high-frequency image noise. Finally, the improved fuzzy set is used to enhance the global contrast and the Laplace operator is used to enhance the details of the medical images. Experiments and simulation results show that the proposed method is superior to existing methods of image noise removal, improves the contrast of the image significantly, and obtains a better visual effect.

  1. Method of Improved Fuzzy Contrast Combined Adaptive Threshold in NSCT for Medical Image Enhancement.

    Science.gov (United States)

    Zhou, Fei; Jia, ZhenHong; Yang, Jie; Kasabov, Nikola

    2017-01-01

    Noises and artifacts are introduced to medical images due to acquisition techniques and systems. This interference leads to low contrast and distortion in images, which not only impacts the effectiveness of the medical image but also seriously affects the clinical diagnoses. This paper proposes an algorithm for medical image enhancement based on the nonsubsampled contourlet transform (NSCT), which combines adaptive threshold and an improved fuzzy set. First, the original image is decomposed into the NSCT domain with a low-frequency subband and several high-frequency subbands. Then, a linear transformation is adopted for the coefficients of the low-frequency component. An adaptive threshold method is used for the removal of high-frequency image noise. Finally, the improved fuzzy set is used to enhance the global contrast and the Laplace operator is used to enhance the details of the medical images. Experiments and simulation results show that the proposed method is superior to existing methods of image noise removal, improves the contrast of the image significantly, and obtains a better visual effect.

  2. An Improved Adaptive Template Size Pixel-Tracking Method for Monitoring Large-Gradient Mining Subsidence

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    Jilei Huang

    2017-01-01

    Full Text Available The monitoring of large-gradient deformation caused by coal mining is of great significance to the prevention and management of disasters in mining areas. The interferometric synthetic aperture radar (InSAR method captures the small-gradient ground deformation on the edge of the subsidence basin accurately but is unreliable for capturing large-gradient deformation. The intensity-based pixel-tracking method (e.g., the normalized cross-correlation (NCC method can overcome the limitations of InSAR’s maximum detectable displacement gradient and incoherence. However, the pixel-tracking method is sensitive to template size. It is difficult to estimate ground subsidence accurately by the conventional pixel-tracking method with fixed template size. In this paper, the signal-to-noise ratio (SNR is redefined and an improved locally adaptive template size method is proposed by identifying optimal template adaptively based on maximization of the redefined SNR. The constraint radius is used to constrain the search area in this improved method. The frequency of misrepresentation is reduced by finding the peak of the correlation coefficient surface within the search area. Both simulation data and real ground subsidence data are used to test this algorithm. The results show that this method can improve monitoring accuracy compared with the traditional pixel-tracking method for fixed template size.

  3. Enhanced detectability of small objects in correlated clutter using an improved 2-D adaptive lattice algorithm.

    Science.gov (United States)

    Ffrench, P A; Zeidler, J H; Ku, W H

    1997-01-01

    Two-dimensional (2-D) adaptive filtering is a technique that can be applied to many image processing applications. This paper will focus on the development of an improved 2-D adaptive lattice algorithm (2-D AL) and its application to the removal of correlated clutter to enhance the detectability of small objects in images. The two improvements proposed here are increased flexibility in the calculation of the reflection coefficients and a 2-D method to update the correlations used in the 2-D AL algorithm. The 2-D AL algorithm is shown to predict correlated clutter in image data and the resulting filter is compared with an ideal Wiener-Hopf filter. The results of the clutter removal will be compared to previously published ones for a 2-D least mean square (LMS) algorithm. 2-D AL is better able to predict spatially varying clutter than the 2-D LMS algorithm, since it converges faster to new image properties. Examples of these improvements are shown for a spatially varying 2-D sinusoid in white noise and simulated clouds. The 2-D LMS and 2-D AL algorithms are also shown to enhance a mammogram image for the detection of small microcalcifications and stellate lesions.

  4. Molecular Docking Improvement: Coefficient Adaptive Genetic Algorithms for Multiple Scoring Functions

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    Zhengfu Li

    2014-03-01

    Full Text Available In this paper, a coefficient adaptive scoring method of molecular docking is presented to improve the docking accuracy with multiple available scoring functions. Based on force-field scoring function, we considered hydrophobic and deformation as well in the proposed method, Instead of simple combination with fixed weights, coefficients of each factor are adaptive in searching procedure. In order to improve the docking accuracy and stability, knowledge-based scoring function is used as another scoring factor. Genetic algorithm with the multi-population evolution and entropy-based searching technique with narrowing down space is used to solve the optimization model for molecular docking. To evaluate the method, we carried out a numerical experiment with 134 protein- ligand complexes of the publicly available GOLD test set. The results validated that it improved the docking accuracy over the individual force-field scoring. In addition, analyses were given to show the disadvantage of individual scoring model. Through the comparison with other popular docking software, the proposed method showed higher accuracy. Among more than 77% of the complexes, the docked results were within 1.0 Å according to Root- Mean-Square Deviation (RMSD of the X-ray structure. The average computing time obtained here is 563.9 s.

  5. Adapted Tango improves aspects of participation in older adults versus individuals with Parkinson's disease.

    Science.gov (United States)

    Zafar, Manal; Bozzorg, Ariyana; Hackney, Madeleine E

    2017-11-01

    Our aims were to determine (1) the impact of aging versus combined aging and disease on participation and (2) participation before and after a 12-week, Adapted Tango dance intervention (AT) in older adults with and without Parkinson's disease (PD). Participant responses to open and closed-ended questions on the Impact on Participation and Autonomy questionnaire (IPA) were recorded before, one-week-after, and three-months after 20 lessons of AT. Twenty-five older individuals with PD and 63 older adults without PD were initially enrolled and assessed, and 44 older adults and 22 individuals with PD finished the program with post-testing. Thematic analysis revealed major themes of difficulty with mobility, transportation and financial management, feelings of being forced to limit activities, and interest in work or volunteering for both groups at baseline and post-test. At post-test, additional emphasis on resilience in the face of challenges was noted. No differences were noted between groups on the IPA subscales at baseline. Quantitative analysis with a 2 (group) × 3 (time) MANOVA revealed a main effect of time (p Tango improved aspects of participation for these cohorts of older adults with and without PD. Implications for Rehabilitation Both Parkinson's disease and neurotypical aging can negatively impact participation in life's activities in older adults. Adapted Tango is an alternative therapy that has improved quality of life and mobility in people with PD and older adults. Quantitative data show that Adapted Tango may improve some aspects of participation for older adults with and without PD. Open-ended responses reveal aging and combined aging and disease-related issues have a lasting impact upon participation.

  6. Bayesian adaptive design: improving the effectiveness of monitoring of the Great Barrier Reef.

    Science.gov (United States)

    Kang, Su Yun; McGree, James M; Drovandi, Christopher C; Caley, M Julian; Mengersen, Kerrie L

    2016-12-01

    Monitoring programs are essential for understanding patterns, trends, and threats in ecological and environmental systems. However, such programs are costly in terms of dollars, human resources, and technology, and complex in terms of balancing short- and long-term requirements. In this work, We develop new statistical methods for implementing cost-effective adaptive sampling and monitoring schemes for coral reef that can better utilize existing information and resources, and which can incorporate available prior information. Our research was motivated by developing efficient monitoring practices for Australia's Great Barrier Reef. We develop and implement two types of adaptive sampling schemes, static and sequential, and show that they can be more informative and cost-effective than an existing (nonadaptive) monitoring program. Our methods are developed in a Bayesian framework with a range of utility functions relevant to environmental monitoring. Our results demonstrate the considerable potential for adaptive design to support improved management outcomes in comparison to set-and-forget styles of surveillance monitoring. © 2016 by the Ecological Society of America.

  7. Improvement of small incision transscleral sulcus fixation of Akreos Adapt AO foldable intraocular lens

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    Tao He

    2015-12-01

    Full Text Available AIM:to observe the effect of modified surgery of small incision transscleral sulcus fixation of Akreos Adapt AO foldable intraocular lens.METHODS:The study included 37 patients(37 eyeswho could not be performed the regular implantation of posterior chamber intraocular lens for the rupture of posterior capsule or for the zonular dialysis caused by trauma, congenital or surgery. Bausch & lomb Akreos Adapt AO fordable intraocular lens, VE22000 implantation device were applied in this study. Regular 2.4mm transparent cornea incision and pocket-like sclera incision were made. The intraocular lens were transscleral sulcus fixed by 10/0 prolene suture and the suture was buried within the scleral incision.RESULTS:The intraocular lenses were all well posited and the postoperative visual acuity(VAwas improved in all patients. Three eyes(8%were≥0.8 while 18 eyes(49%>0.4~≤0.6 and the remaining 16(43%were ≤ 0.4 at 3mo after surgery.Cornea astigmatism was 1.73D±1.22D and 1.62±1.34D before and after surgery, no statistic significance was observed(PCONCLUSION:The modified surgery of 2.4mm small incision transscleral sulcus fixation of Akreos Adapt AO foldable intraocular lens has the following advantages such as:good visual results, less postoperative astigmatism, small surgery incision, steady intraocular lens, less manipulation, less complication and more effective.

  8. Measuring generalization of visuomotor perturbations in wrist movements using mobile phones.

    Science.gov (United States)

    Fernandes, Hugo Liberal; Albert, Mark Vincent; Kording, Konrad Paul

    2011-01-01

    Recent studies in motor control have shown that visuomotor rotations for reaching have narrow generalization functions: what we learn during movements in one direction only affects subsequent movements into close directions. Here we wanted to measure the generalization functions for wrist movement. To do so we had 7 subjects performing an experiment holding a mobile phone in their dominant hand. The mobile phone's built in acceleration sensor provided a convenient way to measure wrist movements and to run the behavioral protocol. Subjects moved a cursor on the screen by tilting the phone. Movements on the screen toward the training target were rotated and we then measured how learning of the rotation in the training direction affected subsequent movements in other directions. We find that generalization is local and similar to generalization patterns of visuomotor rotation for reaching.

  9. Measuring generalization of visuomotor perturbations in wrist movements using mobile phones.

    Directory of Open Access Journals (Sweden)

    Hugo Liberal Fernandes

    Full Text Available Recent studies in motor control have shown that visuomotor rotations for reaching have narrow generalization functions: what we learn during movements in one direction only affects subsequent movements into close directions. Here we wanted to measure the generalization functions for wrist movement. To do so we had 7 subjects performing an experiment holding a mobile phone in their dominant hand. The mobile phone's built in acceleration sensor provided a convenient way to measure wrist movements and to run the behavioral protocol. Subjects moved a cursor on the screen by tilting the phone. Movements on the screen toward the training target were rotated and we then measured how learning of the rotation in the training direction affected subsequent movements in other directions. We find that generalization is local and similar to generalization patterns of visuomotor rotation for reaching.

  10. The Role of Representation Strength of the Prime in Subliminal Visuomotor Priming.

    Science.gov (United States)

    Wang, Yongchun; Wang, Yonghui; Liu, Peng; Di, Meilin; Gong, Yanyan; Tan, Mengge

    2017-11-01

    This study investigated the role of representation strength of the prime in subliminal visuomotor priming in two experiments. Prime/target compatibility (compatible and incompatible) and preposed object type (jumbled lines, strong masking; and rectangular outlines, weak masking) were manipulated in Experiment 1. A significant negative compatibility effect (NCE) was observed in the rectangle condition, whereas no compatibility effect was found in the line condition. However, when a new variable, prime duration, was introduced in Experiment 2, the NCE was reversed with an increase in the prime duration in the rectangle condition, whereas the NCE was maintained in the line condition. This result is consistent with the claim that increasing the prime duration causes the prime representation to be too strong for inhibition in the rectangle condition but strong enough to reliably trigger inhibition in the line condition. The findings demonstrated that prime representation has a causal role in subliminal visuomotor priming.

  11. Characteristic visuomotor influences on eye-movement patterns to faces and other high level stimuli

    Directory of Open Access Journals (Sweden)

    Joseph Michael Arizpe

    2015-07-01

    Full Text Available Eye-movement patterns are often utilized in studies of visual perception as indices of the specific information extracted to efficiently process a given stimulus during a given task. Our prior work, however, revealed that not only the stimulus and task influence eye-movements, but that visuomotor (start position factors also robustly and characteristically influence eye-movement patterns to faces (Arizpe, et al, 2012. Here we manipulated lateral starting side and distance from the midline of face and line-symmetrical control (butterfly stimuli in order to further investigate the nature and generality of such visuomotor influences. First we found that increasing starting distance from midline (4, 8, 12, 16 degrees visual angle strongly and proportionately increased the distance of the first ordinal fixation from midline. We did not find influences of starting distance on subsequent fixations, however, suggesting that eye-movement plans are not strongly affected by starting distance following an initial orienting fixation. Further, we replicated our prior effect of starting side (left, right to induce a spatially contralateral tendency of fixations after the first ordinal fixation. However, we also established that these visuomotor influences did not depend upon the predictability of the location of the upcoming stimulus, and were present not only for face stimuli but also for our control stimulus category (butterflies. We found a correspondence in overall left-lateralized fixation tendency between faces and butterflies. Finally, for faces, we found a relationship between left starting side (right sided fixation pattern tendency and increased recognition performance, which likely reflects a cortical right hemisphere (left visual hemifield advantage for face perception. These results further indicate the importance of considering and controlling for visuomotor influences in the design, analysis, and interpretation of eye-movement studies.

  12. Visuomotor effects of body part movements presented in the first-person perspective on imitative behavior.

    Science.gov (United States)

    Watanabe, Rui; Higuchi, Takahiro; Kikuchi, Yoshiaki; Taira, Masato

    2017-12-01

    Imitative stimuli presented from a first-person perspective (FPP) produce stronger visuomotor effects than those presented from a third-person perspective (TPP) due to the relatively greater response of the mirror neuron system (MNS) to FPP stimuli. Some previous studies utilizing TPP stimuli have reported no differences in MNS activity between moving and static bodies' stimuli. However, few studies have compared visuomotor effects of such stimuli when presented in the FPP. To clarify this issue, we measured cortical activation in 17 participants during a functional magnetic resonance imaging (MRI) imitation task involving three conditions: moving (a lifting finger was presented), static (an "X" appeared on a static finger), and control (an "X" appeared on a button). All stimuli were presented from the FPP or TPP. Participants were asked to lift the finger corresponding to the imitative stimulus. In the FPP condition, moving stimuli elicited greater MNS activation than static stimuli. Furthermore, such movement effects were stronger in the MNS and insula (a region associated with body-ownership) for FPP stimuli than for TPP stimuli. Psychophysiological interaction analysis revealed increased connectivity between the MNS and insula for moving stimuli in the FPP condition. These findings suggest that bodily movements presented in the FPP elicit a greater visuomotor response than static body presented in the FPP, and that the visuomotor effects of bodily movements were greater in the FPP condition than in the TPP condition. Our analyses further indicated that such responses are processed via the neural system underlying body-ownership. Hum Brain Mapp 38:6218-6229, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  13. Dynamic visuomotor transformation involved with remote flying of a plane utilizes the 'Mirror Neuron' system.

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    Daniel E Callan

    Full Text Available Brain regions involved with processing dynamic visuomotor representational transformation are investigated using fMRI. The perceptual-motor task involved flying (or observing a plane through a simulated Red Bull Air Race course in first person and third person chase perspective. The third person perspective is akin to remote operation of a vehicle. The ability for humans to remotely operate vehicles likely has its roots in neural processes related to imitation in which visuomotor transformation is necessary to interpret the action goals in an egocentric manner suitable for execution. In this experiment for 3(rd person perspective the visuomotor transformation is dynamically changing in accordance to the orientation of the plane. It was predicted that 3(rd person remote flying, over 1(st, would utilize brain regions composing the 'Mirror Neuron' system that is thought to be intimately involved with imitation for both execution and observation tasks. Consistent with this prediction differential brain activity was present for 3(rd person over 1(st person perspectives for both execution and observation tasks in left ventral premotor cortex, right dorsal premotor cortex, and inferior parietal lobule bilaterally (Mirror Neuron System (Behaviorally: 1(st>3(rd. These regions additionally showed greater activity for flying (execution over watching (observation conditions. Even though visual and motor aspects of the tasks were controlled for, differential activity was also found in brain regions involved with tool use, motion perception, and body perspective including left cerebellum, temporo-occipital regions, lateral occipital cortex, medial temporal region, and extrastriate body area. This experiment successfully demonstrates that a complex perceptual motor real-world task can be utilized to investigate visuomotor processing. This approach (Aviation Cerebral Experimental Sciences ACES focusing on direct application to lab and field is in contrast to

  14. No Enhancement of 24-Hour Visuomotor Skill Retention by Post-Practice Caffeine Administration.

    Science.gov (United States)

    Hussain, Sara J; Cole, Kelly J

    2015-01-01

    Caffeine is widely consumed throughout the world and appears to indirectly facilitate learning and memory through effects on attention and motivation. Animal work indicates that post-training caffeine administration augments inhibitory avoidance memory, spatial memory, and object memory. In humans, post-training caffeine administration enhances the ability to discern between familiar images and new, similar images. However, the effect of post-training caffeine administration on motor memory has not been examined. Therefore, we tested two groups of low caffeine consumers (average weekly consumption ≤500 mg) in a double-blind, placebo-controlled study involving acquisition of a continuous isometric visuomotor tracking skill. On Day 1, subjects completed 5 blocks (150 repetitions) of training on the continuous isometric visuomotor skill and subsequently ingested either 200 mg of caffeine or placebo. On day 2, subjects completed an additional 5 blocks of training. Day 1 mean performance and performance variability were both similar between groups, suggesting that both groups acquired the motor skill similarly. For mean performance on Day 2, patterns of re-learning, mean performance learning magnitudes, mean performance learning rates, and mean performance retention magnitudes were all similar between groups. For performance variability on Day 2, there was a small trend towards increased variability in the caffeine group during re-learning, but performance variability learning magnitudes and performance variability retention magnitudes did not differ between groups. Because motor skill acquisition can also be conceptualized as a reduction in performance variability, these results suggest that there may be a small negative effect of post-practice caffeine administration on memory of a newly-learned visuomotor skill. Overall, we found no evidence to suggest that post-training caffeine administration enhances 24-hour retention of a newly-learned continuous visuomotor

  15. No Enhancement of 24-Hour Visuomotor Skill Retention by Post-Practice Caffeine Administration.

    Directory of Open Access Journals (Sweden)

    Sara J Hussain

    Full Text Available Caffeine is widely consumed throughout the world and appears to indirectly facilitate learning and memory through effects on attention and motivation. Animal work indicates that post-training caffeine administration augments inhibitory avoidance memory, spatial memory, and object memory. In humans, post-training caffeine administration enhances the ability to discern between familiar images and new, similar images. However, the effect of post-training caffeine administration on motor memory has not been examined. Therefore, we tested two groups of low caffeine consumers (average weekly consumption ≤500 mg in a double-blind, placebo-controlled study involving acquisition of a continuous isometric visuomotor tracking skill. On Day 1, subjects completed 5 blocks (150 repetitions of training on the continuous isometric visuomotor skill and subsequently ingested either 200 mg of caffeine or placebo. On day 2, subjects completed an additional 5 blocks of training. Day 1 mean performance and performance variability were both similar between groups, suggesting that both groups acquired the motor skill similarly. For mean performance on Day 2, patterns of re-learning, mean performance learning magnitudes, mean performance learning rates, and mean performance retention magnitudes were all similar between groups. For performance variability on Day 2, there was a small trend towards increased variability in the caffeine group during re-learning, but performance variability learning magnitudes and performance variability retention magnitudes did not differ between groups. Because motor skill acquisition can also be conceptualized as a reduction in performance variability, these results suggest that there may be a small negative effect of post-practice caffeine administration on memory of a newly-learned visuomotor skill. Overall, we found no evidence to suggest that post-training caffeine administration enhances 24-hour retention of a newly

  16. Use of Adaptive Digital Signal Processing to Improve Speech Communication for Normally Hearing aand Hearing-Impaired Subjects.

    Science.gov (United States)

    Harris, Richard W.; And Others

    1988-01-01

    A two-microphone adaptive digital noise cancellation technique improved word-recognition ability for 20 normal and 12 hearing-impaired adults by reducing multitalker speech babble and speech spectrum noise 18-22 dB. Word recognition improvements averaged 37-50 percent for normal and 27-40 percent for hearing-impaired subjects. Improvement was best…

  17. An improved cooperative adaptive cruise control (CACC) algorithm considering invalid communication

    Science.gov (United States)

    Wang, Pangwei; Wang, Yunpeng; Yu, Guizhen; Tang, Tieqiao

    2014-05-01

    For the Cooperative Adaptive Cruise Control (CACC) Algorithm, existing research studies mainly focus on how inter-vehicle communication can be used to develop CACC controller, the influence of the communication delays and lags of the actuators to the string stability. However, whether the string stability can be guaranteed when inter-vehicle communication is invalid partially has hardly been considered. This paper presents an improved CACC algorithm based on the sliding mode control theory and analyses the range of CACC controller parameters to maintain string stability. A dynamic model of vehicle spacing deviation in a platoon is then established, and the string stability conditions under improved CACC are analyzed. Unlike the traditional CACC algorithms, the proposed algorithm can ensure the functionality of the CACC system even if inter-vehicle communication is partially invalid. Finally, this paper establishes a platoon of five vehicles to simulate the improved CACC algorithm in MATLAB/Simulink, and the simulation results demonstrate that the improved CACC algorithm can maintain the string stability of a CACC platoon through adjusting the controller parameters and enlarging the spacing to prevent accidents. With guaranteed string stability, the proposed CACC algorithm can prevent oscillation of vehicle spacing and reduce chain collision accidents under real-world circumstances. This research proposes an improved CACC algorithm, which can guarantee the string stability when inter-vehicle communication is invalid.

  18. Inferior frontal oscillations reveal visuo-motor matching for actions and speech: evidence from human intracranial recordings.

    Science.gov (United States)

    Halje, Pär; Seeck, Margitta; Blanke, Olaf; Ionta, Silvio

    2015-12-01

    The neural correspondence between the systems responsible for the execution and recognition of actions has been suggested both in humans and non-human primates. Apart from being a key region of this visuo-motor observation-execution matching (OEM) system, the human inferior frontal gyrus (IFG) is also important for speech production. The functional overlap of visuo-motor OEM and speech, together with the phylogenetic history of the IFG as a motor area, has led to the idea that speech function has evolved from pre-existing motor systems and to the hypothesis that an OEM system may exist also for speech. However, visuo-motor OEM and speech OEM have never been compared directly. We used electrocorticography to analyze oscillations recorded from intracranial electrodes in human fronto-parieto-temporal cortex during visuo-motor (executing or visually observing an action) and speech OEM tasks (verbally describing an action using the first or third person pronoun). The results show that neural activity related to visuo-motor OEM is widespread in the frontal, parietal, and temporal regions. Speech OEM also elicited widespread responses partly overlapping with visuo-motor OEM sites (bilaterally), including frontal, parietal, and temporal regions. Interestingly a more focal region, the inferior frontal gyrus (bilaterally), showed both visuo-motor OEM and speech OEM properties independent of orolingual speech-unrelated movements. Building on the methodological advantages in human invasive electrocorticography, the present findings provide highly precise spatial and temporal information to support the existence of a modality-independent action representation system in the human brain that is shared between systems for performing, interpreting and describing actions. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Changes in the spinal neural circuits are dependent on the movement speed of the visuomotor task

    Directory of Open Access Journals (Sweden)

    Shinji eKubota

    2015-12-01

    Full Text Available Previous studies have shown that spinal neural circuits are modulated by motor skill training. However, the effects of task movement speed on changes in spinal neural circuits have not been clarified. The aim of this research was to investigate whether spinal neural circuits were affected by task movement speed. Thirty-eight healthy subjects participated in this study. In experiment 1, the effects of task movement speed on the spinal neural circuits were examined. 18 subjects performed a visuomotor task involving ankle muscle slow (9 subjects or fast (9 subjects movement speed. Another 9 subjects performed a non-visuomotor task (controls in fast movement speed. The motor task training lasted for 20 min. The amounts of D1 inhibition and reciprocal Ia inhibition were measured using H-relfex condition-test paradigm and recorded before, and at 5, 15, and 30 min after the training session. In experiment 2, using transcranial magnetic stimulation (TMS, the effects of corticospinal descending inputs on the presynaptic inhibitory pathway were examined before and after performing either a visuomotor (8 subjects or a control task (8 subjects. All measurements were taken under resting conditions. The amount of D1 inhibition increased after the visuomotor task irrespective of movement speed (P < 0.01. The amount of reciprocal Ia inhibition increased with fast movement speed conditioning (P < 0.01, but was unchanged by slow movement speed conditioning. These changes lasted up to 15 min in D1 inhibition and 5 min in reciprocal Ia inhibition after the training session. The control task did not induce changes in D1 inhibition and reciprocal Ia inhibition. The TMS conditioned inhibitory effects of presynaptic inhibitory pathways decreased following visuomotor tasks (P < 0.01. The size of test H-reflex was almost the same size throughout experiments. The results suggest that supraspinal descending inputs for controlling joint movement are responsible for changes

  20. The effects of a two-step transfer on a visuomotor adaptation task.

    Science.gov (United States)

    Aiken, Christopher A; Pan, Zhujun; Van Gemmert, Arend W A

    2017-11-01

    The literature has shown robust effects of transfer-of-learning to the contralateral side and more recently transfer-of-learning effects to a new effector type on the ipsilateral side. Few studies have investigated the effects of transfer-of-learning when skills transfer to both a new effector type and the contralateral side (two-step transfer). The purpose of the current study was to investigate the effects of two-step transfer and to examine which aspects of the movement transfer and which aspects do not. Individuals practiced a 30° visual rotation task with either the dominant or non-dominant limb and with either the use of the fingers and wrist or elbow and shoulder. Following practice, participants performed the task with the untrained effector type on the contralateral side. Results showed that initial direction error and trajectory length transferred from the dominant to the non-dominant side and movement time transferred from the elbow and shoulder condition to the wrist and finger conditions irrespective of which limb was used during practice. The results offer a unique perspective on the current theoretical and practical implications for transfer-of-learning and are further discussed in this paper.

  1. Adaptive mixed reality rehabilitation improves quality of reaching movements more than traditional reaching therapy following stroke.

    Science.gov (United States)

    Duff, Margaret; Chen, Yinpeng; Cheng, Long; Liu, Sheng-Min; Blake, Paul; Wolf, Steven L; Rikakis, Thanassis

    2013-05-01

    Adaptive mixed reality rehabilitation (AMRR) is a novel integration of motion capture technology and high-level media computing that provides precise kinematic measurements and engaging multimodal feedback for self-assessment during a therapeutic task. We describe the first proof-of-concept study to compare outcomes of AMRR and traditional upper-extremity physical therapy. Two groups of participants with chronic stroke received either a month of AMRR therapy (n = 11) or matched dosing of traditional repetitive task therapy (n = 10). Participants were right handed, between 35 and 85 years old, and could independently reach to and at least partially grasp an object in front of them. Upper-extremity clinical scale scores and kinematic performances were measured before and after treatment. Both groups showed increased function after therapy, demonstrated by statistically significant improvements in Wolf Motor Function Test and upper-extremity Fugl-Meyer Assessment (FMA) scores, with the traditional therapy group improving significantly more on the FMA. However, only participants who received AMRR therapy showed a consistent improvement in kinematic measurements, both for the trained task of reaching to grasp a cone and the untrained task of reaching to push a lighted button. AMRR may be useful in improving both functionality and the kinematics of reaching. Further study is needed to determine if AMRR therapy induces long-term changes in movement quality that foster better functional recovery.

  2. Prism adaptation enhances activity of intact fronto-parietal areas in both hemispheres in neglect patients.

    Science.gov (United States)

    Saj, Arnaud; Cojan, Yann; Vocat, Roland; Luauté, Jacques; Vuilleumier, Patrik

    2013-01-01

    Unilateral spatial neglect involves a failure to report or orient to stimuli in the contralesional (left) space due to right brain damage, with severe handicap in everyday activities and poor rehabilitation outcome. Because behavioral studies suggest that prism adaptation may reduce spatial neglect, we investigated the neural mechanisms underlying prism effects on visuo-spatial processing in neglect patients. We used functional magnetic resonance imaging (fMRI) to examine the effect of (right-deviating) prisms on seven patients with left neglect, by comparing brain activity while they performed three different spatial tasks on the same visual stimuli (bisection, search, and memory), before and after a single prism-adaptation session. Following prism adaptation, fMRI data showed increased activation in bilateral parietal, frontal, and occipital cortex during bisection and visual search, but not during the memory task. These increases were associated with significant behavioral improvement in the same two tasks. Changes in neural activity and behavior were seen only after prism adaptation, but not attributable to mere task repetition. These results show for the first time the neural substrates underlying the therapeutic benefits of prism adaptation, and demonstrate that visuo-motor adaptation induced by prism exposure can restore activation in bilateral brain networks controlling spatial attention and awareness. This bilateral recruitment of fronto-parietal networks may counteract the pathological biases produced by unilateral right hemisphere damage, consistent with recent proposals that neglect may reflect lateralized deficits induced by bilateral hemispheric dysfunction. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Neuromapping: Inflight Evaluation of Cognition and Adaptability

    Science.gov (United States)

    Kofman, I. S.; De Dios, Y. E.; Lawrence, K.; Schade, A.; Reschke, M. F.; Bloomberg, J. J.; Wood, S. J.; Mulavara, A. P.; Seidle, R. D.

    2016-01-01

    In consideration of the health and performance of crewmembers during flight and postflight, we are conducting a controlled prospective longitudinal study to investigate the effects of spaceflight on the extent, longevity and neural bases of sensorimotor, cognitive, and neural changes. Previous studies investigating sensorimotor adaptation to the microgravity environment longitudinally inflight have shown reduction in the ability to perform complex dual tasks. In this study we perform a series of tests investigating the longitudinal effects of adaptation to the microgravity environment and how it affects spatial cognition, manual visuo-motor adaption and dual tasking.

  4. Adapted Bailenger method improves the rate of Ascaris suum eggs recovery from liquid pig manure compost

    Directory of Open Access Journals (Sweden)

    Mariangela Facco de Sá

    Full Text Available ABSTRACT: Liquid pig manure (LPM is widely used as a compost fertilizer for vegetable crops destined for human consumption. However, these wastes may contain parasites eggs, such as the nematode Ascaris suum, that pose serious health risks to humans. We attempted to determine the most appropriate technique for recovering A. suum eggs from LPM compost. Samples were collected from two waste sources during composting, including 23 samples containing LPM, sawdust, and wood shavings, and 14 samples of LPM alone-both in triplicate. Samples were analyzed using several different recovery methods. Recovery of eggs by the modified Bailenger method with adaptations was significantly more effective and recovered 57% more eggs than by the modified Bailenger method alone. Willis-Mollay method, modified Faust method, and the simple sedimentation technique only recovered 4.4%, 13.9%, and 26% of eggs, respectively, compared with the modified Bailenger method with adaptations, indicating that the adjustments made to the Bailenger method were key to improving the recovery of A. suum eggs from compost and LPM.

  5. An improved algorithm for learning long-term dependency problems in adaptive processing of data structures.

    Science.gov (United States)

    Cho, Siu-Yeung; Chi, Zheru; Siu, Wan-Chi; Tsoi, Ah Chung

    2003-01-01

    Many researchers have explored the use of neural-network representations for the adaptive processing of data structures. One of the most popular learning formulations of data structure processing is backpropagation through structure (BPTS). The BPTS algorithm has been successful applied to a number of learning tasks that involve structural patterns such as logo and natural scene classification. The main limitations of the BPTS algorithm are attributed to slow convergence speed and the long-term dependency problem for the adaptive processing of data structures. In this paper, an improved algorithm is proposed to solve these problems. The idea of this algorithm is to optimize the free learning parameters of the neural network in the node representation by using least-squares-based optimization methods in a layer-by-layer fashion. Not only can fast convergence speed be achieved, but the long-term dependency problem can also be overcome since the vanishing of gradient information is avoided when our approach is applied to very deep tree structures.

  6. Study on Adaptive Slid Mode Controller for Improving Handling Stability of Motorized Electric Vehicles

    Directory of Open Access Journals (Sweden)

    LiQiang Jin

    2014-01-01

    Full Text Available An adaptive slid mode controller was established for improving the handling stability of motorized electric vehicle (MEV. First and foremost, the structure and advantages of electric vehicle driven by in-wheel motors will be provided. Then, an ideal cornering model of vehicles will be brought and analyzed, after which a method to estimate side-slip angle was also proposed and three typical sensors were used in the theory. Besides, an idea for the recognition of road adhesion coefficient was derived based on MEV platform, which will be helpful for better control performances. Finally, the scheme of control method was given and some typical tests for observing handling properties were implemented based on Simulink and Carsim software. With the outcomes from the experiments, which vividly showed the merits of the controller, one can come to a conclusion that MEV that equips with the adaptive slid mode controller always enjoys better handling performances than the one without control. Furthermore, the controller researched is friendly to the real-time working conditions, which will hold practical values in the future.

  7. An Efficient Adaptive Window Size Selection Method for Improving Spectrogram Visualization

    Directory of Open Access Journals (Sweden)

    Shibli Nisar

    2016-01-01

    Full Text Available Short Time Fourier Transform (STFT is an important technique for the time-frequency analysis of a time varying signal. The basic approach behind it involves the application of a Fast Fourier Transform (FFT to a signal multiplied with an appropriate window function with fixed resolution. The selection of an appropriate window size is difficult when no background information about the input signal is known. In this paper, a novel empirical model is proposed that adaptively adjusts the window size for a narrow band-signal using spectrum sensing technique. For wide-band signals, where a fixed time-frequency resolution is undesirable, the approach adapts the constant Q transform (CQT. Unlike the STFT, the CQT provides a varying time-frequency resolution. This results in a high spectral resolution at low frequencies and high temporal resolution at high frequencies. In this paper, a simple but effective switching framework is provided between both STFT and CQT. The proposed method also allows for the dynamic construction of a filter bank according to user-defined parameters. This helps in reducing redundant entries in the filter bank. Results obtained from the proposed method not only improve the spectrogram visualization but also reduce the computation cost and achieves 87.71% of the appropriate window length selection.

  8. Pairwise adaptive thermostats for improved accuracy and stability in dissipative particle dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Leimkuhler, Benedict, E-mail: b.leimkuhler@ed.ac.uk; Shang, Xiaocheng, E-mail: x.shang@brown.edu

    2016-11-01

    We examine the formulation and numerical treatment of dissipative particle dynamics (DPD) and momentum-conserving molecular dynamics. We show that it is possible to improve both the accuracy and the stability of DPD by employing a pairwise adaptive Langevin thermostat that precisely matches the dynamical characteristics of DPD simulations (e.g., autocorrelation functions) while automatically correcting thermodynamic averages using a negative feedback loop. In the low friction regime, it is possible to replace DPD by a simpler momentum-conserving variant of the Nosé–Hoover–Langevin method based on thermostatting only pairwise interactions; we show that this method has an extra order of accuracy for an important class of observables (a superconvergence result), while also allowing larger timesteps than alternatives. All the methods mentioned in the article are easily implemented. Numerical experiments are performed in both equilibrium and nonequilibrium settings; using Lees–Edwards boundary conditions to induce shear flow.

  9. Droop Control with Improved Disturbance Adaption for PV System with Two Power Conversion Stages

    DEFF Research Database (Denmark)

    Liu, Hongpeng; Loh, Poh Chiang; Wang, Xiongfei

    2016-01-01

    with no or insufficient storage for cushioning climatic changes. In addition, most droop-controlled literatures have assumed a single dc-ac inverter with its input dc source fixed. Front-end dc-dc converter added to a two-stage photovoltaic (PV) system has therefore usually been ignored. To address these unresolved...... issues, an improved droop scheme for a two-stage PV system has been developed in the paper. The developed scheme uses the same control structure in both grid-connected and islanded modes, which together with properly tuned synchronizers, allows mode transfer to be seamlessly triggered. Moreover......, the proposed scheme adapts well with internal PV and external grid fluctuations, and is hence more precise with its tracking, as compared with the traditional droop scheme. Simulation and experimental results have verified these expectations, and hence the effectiveness of the proposed scheme....

  10. Joint-Angle Specific Strength Adaptations Influence Improvements in Power in Highly Trained Athletes

    Directory of Open Access Journals (Sweden)

    Rhea Matthew R.

    2016-03-01

    Full Text Available Purpose. The purpose of this study was to examine the influence of training at different ranges of motion during the squat exercise on joint-angle specific strength adaptations. Methods. Twenty eight men were randomly assigned to one of three training groups, differing only in the depth of squats (quarter squat, half squat, and full squat performed in 16-week training intervention. Strength measures were conducted in the back squat pre-, mid-, and post-training at all three depths. Vertical jump and 40-yard sprint time were also measured. Results. Individuals in the quarter and full squat training groups improved significantly more at the specific depth at which they trained when compared to the other two groups (p < 0.05. Jump height and sprint speed improved in all groups (p < 0.05; however, the quarter squat had the greatest transfer to both outcomes. Conclusions. Consistently including quarter squats in workouts aimed at maximizing speed and jumping power can result in greater improvements.

  11. An adaptive grid to improve the efficiency and accuracy of modelling underwater noise from shipping

    Science.gov (United States)

    Trigg, Leah; Chen, Feng; Shapiro, Georgy; Ingram, Simon; Embling, Clare

    2017-04-01

    represents a 2 to 5-fold increase in efficiency. The 5 km grid reduces the number of model executions further to 1024. However, over the first 25 km the 5 km grid produces errors of up to 13.8 dB when compared to the highly accurate but inefficient 1 km grid. The newly developed adaptive grid generates much smaller errors of less than 0.5 dB while demonstrating high computational efficiency. Our results show that the adaptive grid provides the ability to retain the accuracy of noise level predictions and improve the efficiency of the modelling process. This can help safeguard sensitive marine ecosystems from noise pollution by improving the underwater noise predictions that inform management activities. References Shapiro, G., Chen, F., Thain, R., 2014. The Effect of Ocean Fronts on Acoustic Wave Propagation in a Shallow Sea, Journal of Marine System, 139: 217 - 226. http://dx.doi.org/10.1016/j.jmarsys.2014.06.007.

  12. Improving the use of crop models for risk assessment and climate change adaptation.

    Science.gov (United States)

    Challinor, Andrew J; Müller, Christoph; Asseng, Senthold; Deva, Chetan; Nicklin, Kathryn Jane; Wallach, Daniel; Vanuytrecht, Eline; Whitfield, Stephen; Ramirez-Villegas, Julian; Koehler, Ann-Kristin

    2018-01-01

    Crop models are used for an increasingly broad range of applications, with a commensurate proliferation of methods. Careful framing of research questions and development of targeted and appropriate methods are therefore increasingly important. In conjunction with the other authors in this special issue, we have developed a set of criteria for use of crop models in assessments of impacts, adaptation and risk. Our analysis drew on the other papers in this special issue, and on our experience in the UK Climate Change Risk Assessment 2017 and the MACSUR, AgMIP and ISIMIP projects. The criteria were used to assess how improvements could be made to the framing of climate change risks, and to outline the good practice and new developments that are needed to improve risk assessment. Key areas of good practice include: i. the development, running and documentation of crop models, with attention given to issues of spatial scale and complexity; ii. the methods used to form crop-climate ensembles, which can be based on model skill and/or spread; iii. the methods used to assess adaptation, which need broadening to account for technological development and to reflect the full range options available. The analysis highlights the limitations of focussing only on projections of future impacts and adaptation options using pre-determined time slices. Whilst this long-standing approach may remain an essential component of risk assessments, we identify three further key components: 1.Working with stakeholders to identify the timing of risks. What are the key vulnerabilities of food systems and what does crop-climate modelling tell us about when those systems are at risk?2.Use of multiple methods that critically assess the use of climate model output and avoid any presumption that analyses should begin and end with gridded output.3.Increasing transparency and inter-comparability in risk assessments. Whilst studies frequently produce ranges that quantify uncertainty, the assumptions

  13. Difference rather than delay in development of elementary visuomotor processes in children born preterm without Celebral Palsy : A quasi-longitudinal study

    NARCIS (Netherlands)

    Van Braeckel, K.N.J.A.; Butcher, P.R.; Geuze, R.H.; van Duijn, M.A.J.; Bos, Arie; Bouma, Anke

    Follow-up studies of preterm children without serious neonatal medical complications have consistently found poor visuomotor and visuospatial skills. In the first round of current follow-up study, we found a deficit in elementary visuomotor processes in preterm children without Cerebral Palsy (CP).

  14. An event-related potential evoked by movement planning is modulated by performance and learning in visuomotor control.

    Science.gov (United States)

    Hill, Holger

    2009-06-01

    Based on a previous exploratory study, the functionality of event-related potentials related to visuomotor processing and learning was investigated. Three pursuit tracking tasks (cursor control either mouse, joystick, or bimanually) revealed the greatest tracking error and greatest learning effect in the bimanual task. The smallest error without learning was found in the mouse task. Error reduction reflected visuomotor learning. In detail, target-cursor distance was reduced continuously, indicating a better fit to a changed direction, whereas response time remained at 300 ms. A central positive ERP component with an activity onset 100 ms after a directional change of the target and most likely generated in premotor areas could be assigned to response planning and execution. The magnitude of this component was modulated by within-and-between-task difficulty and size of the tracking error. Most importantly, the size of this component was sensitive to between-subject performance and increased with visuomotor learning.

  15. Adaptive Wavelet Threshold Denoising Method for Machinery Sound Based on Improved Fruit Fly Optimization Algorithm

    Directory of Open Access Journals (Sweden)

    Jing Xu

    2016-07-01

    Full Text Available As the sound signal of a machine contains abundant information and is easy to measure, acoustic-based monitoring or diagnosis systems exhibit obvious superiority, especially in some extreme conditions. However, the sound directly collected from industrial field is always polluted. In order to eliminate noise components from machinery sound, a wavelet threshold denoising method optimized by an improved fruit fly optimization algorithm (WTD-IFOA is proposed in this paper. The sound is firstly decomposed by wavelet transform (WT to obtain coefficients of each level. As the wavelet threshold functions proposed by Donoho were discontinuous, many modified functions with continuous first and second order derivative were presented to realize adaptively denoising. However, the function-based denoising process is time-consuming and it is difficult to find optimal thresholds. To overcome these problems, fruit fly optimization algorithm (FOA was introduced to the process. Moreover, to avoid falling into local extremes, an improved fly distance range obeying normal distribution was proposed on the basis of original FOA. Then, sound signal of a motor was recorded in a soundproof laboratory, and Gauss white noise was added into the signal. The simulation results illustrated the effectiveness and superiority of the proposed approach by a comprehensive comparison among five typical methods. Finally, an industrial application on a shearer in coal mining working face was performed to demonstrate the practical effect.

  16. Improving reflectance reconstruction from tristimulus values by adaptively combining colorimetric and reflectance similarities

    Science.gov (United States)

    Cao, Bin; Liao, Ningfang; Li, Yasheng; Cheng, Haobo

    2017-05-01

    The use of spectral reflectance as fundamental color information finds application in diverse fields related to imaging. Many approaches use training sets to train the algorithm used for color classification. In this context, we note that the modification of training sets obviously impacts the accuracy of reflectance reconstruction based on classical reflectance reconstruction methods. Different modifying criteria are not always consistent with each other, since they have different emphases; spectral reflectance similarity focuses on the deviation of reconstructed reflectance, whereas colorimetric similarity emphasizes human perception. We present a method to improve the accuracy of the reconstructed spectral reflectance by adaptively combining colorimetric and spectral reflectance similarities. The different exponential factors of the weighting coefficients were investigated. The spectral reflectance reconstructed by the proposed method exhibits considerable improvements in terms of the root-mean-square error and goodness-of-fit coefficient of the spectral reflectance errors as well as color differences under different illuminants. Our method is applicable to diverse areas such as textiles, printing, art, and other industries.

  17. Adaptive OFDM Radar Waveform Design for Improved Micro-Doppler Estimation

    Energy Technology Data Exchange (ETDEWEB)

    Sen, Satyabrata [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Engineering Science Advanced Research, Computer Science and Mathematics Division

    2014-07-01

    Here we analyze the performance of a wideband orthogonal frequency division multiplexing (OFDM) signal in estimating the micro-Doppler frequency of a rotating target having multiple scattering centers. The use of a frequency-diverse OFDM signal enables us to independently analyze the micro-Doppler characteristics with respect to a set of orthogonal subcarrier frequencies. We characterize the accuracy of micro-Doppler frequency estimation by computing the Cramer-Rao bound (CRB) on the angular-velocity estimate of the target. Additionally, to improve the accuracy of the estimation procedure, we formulate and solve an optimization problem by minimizing the CRB on the angular-velocity estimate with respect to the OFDM spectral coefficients. We present several numerical examples to demonstrate the CRB variations with respect to the signal-to-noise ratios, number of temporal samples, and number of OFDM subcarriers. We also analysed numerically the improvement in estimation accuracy due to the adaptive waveform design. A grid-based maximum likelihood estimation technique is applied to evaluate the corresponding mean-squared error performance.

  18. Prism adaptation improves ego-centered but not allocentric neglect in early rehabilitation patients.

    Science.gov (United States)

    Gossmann, Anja; Kastrup, Andreas; Kerkhoff, Georg; López-Herrero, Carmen; Hildebrandt, Helmut

    2013-01-01

    Unilateral neglect due to parieto-temporo-frontal lesions has a negative impact on the success of rehabilitation, and prism adaptation (PA) enhances recovery from neglect. However, it is unclear if this effect holds also in severely impaired patients and/or in the postacute phase of rehabilitation. Moreover, it is not known whether PA affects all aspects of neglect recovery or ego-centered spatial orientation only. Sixteen patients in a postacute stage (on average 36 days after a large right cerebrovascular stroke) were entered into a series of single case design studies with 4 measurements: 2 before and 2 after 1 week of PA treatment. All patients had severe neglect (showing trunk, head, and eye deviation; canceling less than 20% of targets in a visual cancellation test). Lesions were transferred to a standard brain to analyze size and location. Patients improved in cued body orientation and in the cancellation task, that is, in ego-centered neglect. However, none of the measures used to evaluate neglect of left side of objects irrespective of their position on the right or left side of the patient (allocentric neglect) showed an improvement. Treatment effects were not influenced by total lesion size, but lesions including the postcentral cortex were related to smaller recovery gains. PA is helpful in treating severely impaired patients in the postacute phase, but the effect is restricted to ego-centered neglect. Lesions in the postcentral cortex (middle occipito-temporal, middle temporal, and posterior parietal areas) seem to limit the effect of PA.

  19. Effects of alcohol conditioning and expectancy on a visuo-motor integration task.

    Science.gov (United States)

    Thomson, J B; Newlin, D B

    1988-01-01

    Two experiments were performed in which the classical conditioning model of tolerance, the habituation theory of tolerance, and state dependent learning theory made conflicting predictions. In the first experiment, alcohol conditioning did not produce a compensatory response under placebo on a visuo-motor integration task, but disguised alcohol produced a large decrement in performance. Since the results were consistent both with habituation and state dependent learning theories, a second experiment was performed in which all subjects received alcohol, but half were told that they were receiving pure tonic water. The finding of no expectancy effect was inconsistent with habituation theory, but fully consistent with state dependent learning theory.

  20. Scheduled evening sleep and enhanced lighting improve adaptation to night shift work in older adults.

    Science.gov (United States)

    Chinoy, Evan D; Harris, Michael P; Kim, Min Ju; Wang, Wei; Duffy, Jeanne F

    2016-12-01

    We tested whether a sleep and circadian-based treatment shown to improve circadian adaptation to night shifts and attenuate negative effects on alertness, performance and sleep in young adults would also be effective in older adults. We assessed subjective alertness, sustained attention (psychomotor vigilance task, PVT), sleep duration (actigraphy) and circadian timing (salivary dim-light melatonin onset, DLMO) in 18 older adults (57.2±3.8 years; mean±SD) in a simulated shift work protocol. 4 day shifts were followed by 3 night shifts in the laboratory. Participants slept at home and were randomised to either the treatment group (scheduled evening sleep and enhanced lighting during the latter half of night shifts) or control group (ad-lib sleep and typical lighting during night shifts). Compared with day shifts, alertness and sustained attention declined on the first night shift in both groups, and was worse in the latter half of the night shifts. Alertness and attention improved on nights 2 and 3 for the treatment group but remained lower for the control group. Sleep duration in the treatment group remained similar to baseline (6-7 hours) following night shifts, but was shorter (3-5 hours) following night shifts in the control group. Treatment group circadian timing advanced by 169.3±16.1 min (mean±SEM) but did not shift (-9.7±9.9 min) in the control group. The combined treatment of scheduled evening sleep and enhanced lighting increased sleep duration and partially aligned circadian phase with sleep and work timing, resulting in improved night shift alertness and performance. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  1. Scheduled Evening Sleep and Enhanced Lighting Improve Adaptation to Night Shift Work in Older Adults

    Science.gov (United States)

    Chinoy, Evan D.; Harris, Michael P.; Kim, Min Ju; Wang, Wei; Duffy, Jeanne F.

    2017-01-01

    Objectives We tested whether a sleep and circadian-based treatment shown to improve circadian adaptation to night shifts and attenuate negative effects on alertness, performance, and sleep in young adults would also be effective in older adults. Methods We assessed subjective alertness, sustained attention (psychomotor vigilance task, PVT), sleep duration (actigraphy), and circadian timing (salivary dim-light melatonin onset, DLMO) in eighteen older adults (57.2±3.8 y; mean±SD) in a simulated shift work protocol. Four day shifts were followed by three night shifts in the laboratory. Participants slept at home and were randomized to either the Treatment Group (scheduled evening sleep and enhanced lighting during the latter half of night shifts), or Control Group (ad lib sleep and typical lighting during night shifts). Results Compared to day shifts, alertness and sustained attention declined on the first night shift in both groups, and was worse in the latter half of the night shifts. Alertness and attention improved on nights 2 and 3 for the Treatment Group but remained lower for the Control Group. Sleep duration in the Treatment Group remained similar to baseline (6–7 h) following night shifts, but was shorter (3–5 h) following night shifts in the Control Group. Treatment Group circadian timing advanced by 169.3±16.1 min (mean±SEM) but did not shift (−9.7±9.9 min) in the Control Group. Conclusions The combined treatment of scheduled evening sleep and enhanced lighting increased sleep duration and partially aligned circadian phase with sleep and work timing, resulting in improved night shift alertness and performance. PMID:27566781

  2. Visually guided reaching: bilateral posterior parietal lesions cause a switch from fast visuomotor to slow cognitive control.

    Science.gov (United States)

    Rossetti, Y; Revol, P; McIntosh, R; Pisella, L; Rode, G; Danckert, J; Tilikete, C; Dijkerman, H C; Boisson, D; Vighetto, A; Michel, F; Milner, A D

    2005-01-01

    The visually guided reaching of two patients with bilateral optic ataxia was explored in two experiments. In Experiment 1 simple delayed pointing was compared with immediate pointing. In the immediate pointing task both variable and constant errors increased with target eccentricity. In contrast to the performance of control subjects and contrary to their own beliefs, the patients both showed improved accuracy in the delay condition. This improvement was manifest as a reduction in both pointing variability and in the constant angular error towards the point of fixation. Both angular errors and their improvement with the delay were proportional to target eccentricity. Experiment 2 used a task in which the target was pre-viewed 5s prior to its re-exposure for pointing ('delayed real pointing'). On some trials a conflict was introduced between the present and previous visual information by changing the target's location during the delay. In contrast to control subjects, who ignored the pre-viewed location and aimed directly at the current target, both patients with optic ataxia initiated their movements towards the previously viewed target location. Evidently they relied on off-line information in preference to on-line visual information. In addition, the patients often failed to detect the changes in target location. One of the patients sometimes even guessed incorrectly that the target had changed its location, and her movement trajectory was then more affected by her false belief than by the target's actual location. These findings confirm that posterior parietal lesions severely disrupt direct visuomotor transformations, and suggest that the residual performance is mediated indirectly by expectations or beliefs about target position.

  3. Adaptive statistical iterative reconstruction improves image quality without affecting perfusion CT quantitation in primary colorectal cancer.

    Science.gov (United States)

    Prezzi, D; Goh, V; Virdi, S; Mallett, S; Grierson, C; Breen, D J

    2017-01-01

    To determine the effect of Adaptive Statistical Iterative Reconstruction (ASIR) on perfusion CT (pCT) parameter quantitation and image quality in primary colorectal cancer. Prospective observational study. Following institutional review board approval and informed consent, 32 patients with colorectal adenocarcinoma underwent pCT (100 kV, 150 mA, 120 s acquisition, axial mode). Tumour regional blood flow (BF), blood volume (BV), mean transit time (MTT) and permeability surface area product (PS) were determined using identical regions-of-interests for ASIR percentages of 0%, 20%, 40%, 60%, 80% and 100%. Image noise, contrast-to-noise ratio (CNR) and pCT parameters were assessed across ASIR percentages. Coefficients of variation (CV), repeated measures analysis of variance (rANOVA) and Spearman' rank order correlation were performed with statistical significance at 5%. With increasing ASIR percentages, image noise decreased by 33% while CNR increased by 61%; peak tumour CNR was greater than 1.5 with 60% ASIR and above. Mean BF, BV, MTT and PS differed by less than 1.8%, 2.9%, 2.5% and 2.6% across ASIR percentages. CV were 4.9%, 4.2%, 3.3% and 7.9%; rANOVA P values: 0.85, 0.62, 0.02 and 0.81 respectively. ASIR improves image noise and CNR without altering pCT parameters substantially.

  4. Adaptive Focused Acoustics (AFA) Improves the Performance of Microtiter Plate ELISAs.

    Science.gov (United States)

    Green, David J; Rudd, Edwin A; Laugharn, James A

    2014-08-01

    We investigated the use of Adaptive Focused Acoustics (AFA) technology to improve the performance of microtiter plate enzyme-linked immunosorbent assays (ELISAs). Experiments were performed with commercially available AFA instrumentation and off-the-shelf 96-well microtiter plate sandwich ELISAs. AFA was applied over a range of acoustic energies, temperatures, and durations to the antigen/antibody binding step of an ELISA for measuring HIV-1 p24 in tissue culture samples. AFA-mediated antigen/antibody binding was enhanced up to 2-fold over passive binding at comparable temperatures and was superior or comparable at low temperature (8-10 °C) to passive binding at 37 °C. Lower nonspecific binding (NSB), lower inter- and intra-assay coefficients of variation (CVs), higher Z' factors, and lower limits of detection (LODs) were measured in AFA-mediated assays compared with conventional passive binding. In a more limited study, AFA enhancement of antigen/antibody binding and lower NSB was measured in an ELISA for measuring IGFBP-3 in human plasma. We conclude from this study that application of AFA to antigen/antibody binding steps in microtiter plate ELISAs can enhance key assay performance parameters, particularly Z' factors and LODs. These features render AFA-mediated binding assays potentially more useful in applications such as high-throughput screening and in vitro diagnostics than assays processed with conventional passive antigen/antibody binding steps. © 2014 Society for Laboratory Automation and Screening.

  5. Improving conservation outcomes with a new paradigm for understanding species’ fundamental and realized adaptive capacity

    Science.gov (United States)

    Beever, Erik; O’Leary, John; Mengelt, Claudia; West, Jordan M.; Julius, Susan; Green, Nancy; Magness, Dawn; Petes, Laura E.; Stein, Bruce A.; Nicotra, Adrienne B; Hellmann, Jessica J; Robertson, Amanda L; Staudinger, Michelle D.; Rosenberg, Andrew A.; Babij, Eleanora; Brennan, Jean; Schuurman, Gregor W.; Hofmann, Gretchen E

    2016-01-01

    Worldwide, many species are responding to ongoing climate change with shifts in distribution, abundance, phenology, or behavior. Consequently, natural-resource managers face increasingly urgent conservation questions related to biodiversity loss, expansion of invasive species, and deteriorating ecosystem services. We argue that our ability to address these questions is hampered by the lack of explicit consideration of species’ adaptive capacity (AC). AC is the ability of a species or population to cope with climatic changes and is characterized by three fundamental components: phenotypic plasticity, dispersal ability, and genetic diversity. However, few studies simultaneously address all elements; often, AC is confused with sensitivity or omitted altogether from climate-change vulnerability assessments. Improved understanding, consistent definition, and comprehensive evaluations of AC are needed. Using classic ecological-niche theory as an analogy, we propose a new paradigm that considers fundamental and realized AC: the former reflects aspects inherent to species, whereas the latter denotes how extrinsic factors constrain AC to what is actually expressed or observed. Through this conceptualization, we identify ecological attributes contributing to AC, outline areas of research necessary to advance understanding of AC, and provide examples demonstrating how the inclusion of AC can better inform conservation and natural-resource management.

  6. Glucagon-like peptide 2 treatment may improve intestinal adaptation during weaning

    DEFF Research Database (Denmark)

    Thymann, Thomas; Le Huërou-Luron, I; Petersen, Y M

    2014-01-01

    Transition from sow’s milk to solid feed is associated with intestinal atrophy and diarrhea. We hypothesized that the intestinotrophic hormone glucagon-like peptide 2 (GLP-2) would induce a dose- and health status-dependent effect on gut adaptation. In Exp. 1, weaned pigs (average BW at weaning 4.......98 ± 0.18 kg) were kept in a high-sanitary environment and injected with saline or short-acting GLP-2 (80 μg/(kg BW·12 h); n = 8). Under these conditions, there was no diarrhea and GLP-2 did not improve gastrointestinal structure or function. In Exp. 2, weaned pigs (average BW at weaning 6.68 ± 0.27 kg...... effects on diarrhea. In Exp. 3, weaned pigs (average BW at weaning 6.90 ± 0.32 kg) were kept in a low-sanitary environment and injected with saline or a long-acting acylated GLP-2 analogue (25 µg/(kg BW·12 h); n = 8). In this experiment, GLP-2 increased intestinal weight (+22%; P

  7. Assessing Continuous Quality Improvement in Public Health: Adapting Lessons from Healthcare.

    Science.gov (United States)

    Price, Alex; Schwartz, Robert; Cohen, Joanna; Manson, Heather; Scott, Fran

    2017-02-01

    Evidence of the effect of continuous quality improvement (CQI) in public health and valid tools to judge that such effects are not fully formed. The objective was to adapt and apply Shortell et al.'s (1998) four dimensions of CQI in an examination of a public health accountability and performance management initiative in Ontario, Canada. In total, 24 semi-structured, in-depth interviews were conducted with informants from public health units and the Ministry of Health and Long-Term Care. A web survey of public health managers in the province was also carried out. A mix of facilitators and barriers was identified. Leadership and organizational cultures, conducive to CQI success were evident. However, limitations in performance measurement and managerial discretion were key barriers. The four dimensions of CQI provided insight into both facilitators and barriers of CQI adoption in public health. Future research should compare the outcomes of public health CQI initiatives to the framework's stated facilitators and barriers. Copyright © 2017 Longwoods Publishing.

  8. A new adaptive controller of facts-based FMRLC aimed at improving power system stability

    Directory of Open Access Journals (Sweden)

    Abdellatif Naceri

    2008-01-01

    Full Text Available Various control techniques using Advanced Super-conducting Magnetic Energy Storage (ASMES aimed at improving power system stability have been proposed. As fuzzy controller has proved its value in some applications, the number of investigations employing fuzzy controller with ASMES has been greatly increased over recent period. Nevertheless, it is sometimes difficult to specify the rule base for some plants, or the need can arise for tuning the rule-base parameters if the plant changes. In order to solve such problems the Fuzzy Model Reference Learning Controller (FMRLC is proposed. This paper investigates multi-inputs/multi-outputs FMRLC for time-variant nonlinear system. This provides the motivation for adaptive fuzzy control, whereby the focus is placed on the automatic on-line synthesis and tuning of fuzzy controller parameters (i.e., the use of on-line data for continuous learning of the fuzzy controller which ensures that the performance objectives are met. The simulation results show that the proposed robust controller is able to work with nonlinear power system (i.e., single machine connected at infinite bus, under various fault conditions and significant disturbances.

  9. Improving our legacy: Incorporation of adaptive management into state wildlife action plans

    Science.gov (United States)

    Fontaine, J.J.

    2011-01-01

    The loss of biodiversity is a mounting concern, but despite numerous attempts there are few large scale conservation efforts that have proven successful in reversing current declines. Given the challenge of biodiversity conservation, there is a need to develop strategic conservation plans that address species declines even with the inherent uncertainty in managing multiple species in complex environments. In 2002, the State Wildlife Grant program was initiated to fulfill this need, and while not explicitly outlined by Congress follows the fundamental premise of adaptive management, 'Learning by doing'. When action is necessary, but basic biological information and an understanding of appropriate management strategies are lacking, adaptive management enables managers to be proactive in spite of uncertainty. However, regardless of the strengths of adaptive management, the development of an effective adaptive management framework is challenging. In a review of 53 State Wildlife Action Plans, I found a keen awareness by planners that adaptive management was an effective method for addressing biodiversity conservation, but the development and incorporation of explicit adaptive management approaches within each plan remained elusive. Only ???25% of the plans included a framework for how adaptive management would be implemented at the project level within their state. There was, however, considerable support across plans for further development and implementation of adaptive management. By furthering the incorporation of adaptive management principles in conservation plans and explicitly outlining the decision making process, states will be poised to meet the pending challenges to biodiversity conservation. ?? 2010 .

  10. Enhanced visuomotor processing of phobic images in blood-injury-injection fear.

    Science.gov (United States)

    Haberkamp, Anke; Schmidt, Thomas

    2014-04-01

    Numerous studies have identified attentional biases and processing enhancements for fear-relevant stimuli in individuals with specific phobias. However, this has not been conclusively shown in blood-injury-injection (BII) phobia, which has rarely been investigated even though it has features distinct from all other specific phobias. The present study aims to fill that gap and compares the time-course of visuomotor processing of phobic stimuli (i.e., pictures of small injuries) in BII-fearful (n=19) and non-anxious control participants (n=23) by using a response priming paradigm. In BII-fearful participants, phobic stimuli produced larger priming effects and lower response times compared to neutral stimuli, whereas non-anxious control participants showed no such differences. Because these effects are fully present in the fastest responses, they indicate an enhancement in early visuomotor processing of injury pictures in BII-fearful participants. These results are comparable to the enhanced processing of phobic stimuli in other specific phobias (i.e., spider phobia). Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. The robot hand illusion: inducing proprioceptive drift through visuo-motor congruency.

    Science.gov (United States)

    Romano, Daniele; Caffa, Elisa; Hernandez-Arieta, Alejandro; Brugger, Peter; Maravita, Angelo

    2015-04-01

    The representation of one's own body sets the border of the self, but also shapes the space where we interact with external objects. Under particular conditions, such as in the rubber hand illusion external objects can be incorporated in one's own body representation, following congruent visuo-tactile stroking of one's own and a fake hand. This procedure induces an illusory sense of ownership for the fake hand and a shift of proprioceptive localization of the own hand towards the fake hand. Here we investigated whether pure visuo-motor, instead of visuo-tactile, congruency between one's own hand and a detached myoelectric-controlled robotic hand can induce similar embodiment effects. We found a shift of proprioceptive hand localization toward the robot hand, only following synchronized real hand/robot hand movements. Notably, no modulation was found of the sense of ownership following either synchronous or asynchronous-movement training. Our findings suggest that visuo-motor synchrony can drive the localization of one's own body parts in space, even when somatosensory input is kept constant and the experience of body ownership is maintained. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Close interpersonal proximity modulates visuomotor processing of object affordances in shared, social space.

    Science.gov (United States)

    Saccone, Elizabeth J; Szpak, Ancret; Churches, Owen; Nicholls, Michael E R

    2018-01-01

    Research suggests that the human brain codes manipulable objects as possibilities for action, or affordances, particularly objects close to the body. Near-body space is not only a zone for body-environment interaction but also is socially relevant, as we are driven to preserve our near-body, personal space from others. The current, novel study investigated how close proximity of a stranger modulates visuomotor processing of object affordances in shared, social space. Participants performed a behavioural object recognition task both alone and with a human confederate. All object images were in participants' reachable space but appeared relatively closer to the participant or the confederate. Results revealed when participants were alone, objects in both locations produced an affordance congruency effect but when the confederate was present, only objects nearer the participant elicited the effect. Findings suggest space is divided between strangers to preserve independent near-body space boundaries, and in turn this process influences motor coding for stimuli within that social space. To demonstrate that this visuomotor modulation represents a social phenomenon, rather than a general, attentional effect, two subsequent experiments employed nonhuman joint conditions. Neither a small, Japanese, waving cat statue (Experiment 2) nor a metronome (Experiment 3) modulated the affordance effect as in Experiment 1. These findings suggest a truly social explanation of the key interaction from Experiment 1. This study represents an important step toward understanding object affordance processing in real-world, social contexts and has implications broadly across fields of social action and cognition, and body space representation.

  13. Influence of stimulus velocity profile on unintentional visuomotor entrainment depends on eye movements.

    Science.gov (United States)

    Varlet, Manuel; Schmidt, R C; Richardson, Michael J

    2017-11-01

    Humans spontaneously entrain their movements to visual rhythms in the environment. Previous research has shown that the strength of such unintentional visuomotor entrainment is enhanced when observing rhythms characterized by the nonlinear, Rayleigh kinematics typical of human movements; such movements are characterized by greater slowness towards the trajectory turning points compared to sinusoidal movements. However, the enhanced unintentional entrainment to rhythms exhibiting Rayleigh kinematics has only been shown to occur when participants tracked stimulus movements with their eyes, which might have facilitated access to important information for enhanced entrainment. The current study compared the strength of unintentional visuomotor entrainment with both Rayleigh and sinusoidal kinematics when participants were either tracking (eye following the oscillating stimulus) or non-tracking (eye fixed at the centre of the stimulus trajectory) stimulus movements. The results showed that enhanced unintentional entrainment with Rayleigh stimuli only occurred with eye-tracking, supporting that slowness of rhythmic movements towards turning points facilitate entrainment and that access to this information depends on eye movements.

  14. Improving adaptation to weaning: Effect of intermittent suckling regimens on piglet feed intake, growth, and gut characteristics

    NARCIS (Netherlands)

    Berkeveld, M.; Langendijk, P.; Soede, N.M.; Kemp, B.; Taverne, M.A.M.; Verheijden, J.H.M.; Kuijken, N.; Koets, A.P.

    2009-01-01

    Daily separation of sows and piglets during lactation, intermittent suckling (IS), improves feed intake and postweaning adaptation in piglets. The aim of the current study was to determine how, in piglets that have been subjected to IS, age at weaning and the duration of the preceding IS period

  15. A community based approach to improving resilience of forests and water resources: A local and regional climate adaptation methodology

    Science.gov (United States)

    Toby Thaler; Gwen Griffith; Nancy Gilliam

    2014-01-01

    Forest-based ecosystem services are at risk from human-caused stressors, including climate change. Improving governance and management of forests to reduce impacts and increase community resilience to all stressors is the objective of forest-related climate change adaptation. The Model Forest Policy Program (MFPP) has applied one method designed to meet this objective...

  16. Usability of an adaptive computer assistant that improves self-care and health literacy of older adults

    NARCIS (Netherlands)

    Blanson Henkemans, O.A.; Rogers, W.A.; Fisk, A.D.; Neerincx, M.A.; Lindenberg, J.; Mast, C.A.P.G. van der

    2008-01-01

    Objectives: We developed an adaptive computer assistant for the supervision of diabetics' self-care, to support limiting illness and need for acute treatment, and improve health literacy. This assistant monitors self-care activities logged in the patient's electronic diary. Accordingly, it provides

  17. Bearing Fault Diagnosis Based on Improved Locality-Constrained Linear Coding and Adaptive PSO-Optimized SVM

    Directory of Open Access Journals (Sweden)

    Haodong Yuan

    2017-01-01

    Full Text Available A novel bearing fault diagnosis method based on improved locality-constrained linear coding (LLC and adaptive PSO-optimized support vector machine (SVM is proposed. In traditional LLC, each feature is encoded by using a fixed number of bases without considering the distribution of the features and the weight of the bases. To address these problems, an improved LLC algorithm based on adaptive and weighted bases is proposed. Firstly, preliminary features are obtained by wavelet packet node energy. Then, dictionary learning with class-wise K-SVD algorithm is implemented. Subsequently, based on the learned dictionary the LLC codes can be solved using the improved LLC algorithm. Finally, SVM optimized by adaptive particle swarm optimization (PSO is utilized to classify the discriminative LLC codes and thus bearing fault diagnosis is realized. In the dictionary leaning stage, other methods such as selecting the samples themselves as dictionary and K-means are also conducted for comparison. The experiment results show that the LLC codes can effectively extract the bearing fault characteristics and the improved LLC outperforms traditional LLC. The dictionary learned by class-wise K-SVD achieves the best performance. Additionally, adaptive PSO-optimized SVM can greatly enhance the classification accuracy comparing with SVM using default parameters and linear SVM.

  18. Computer-Based Adaptive Instructional Strategies for the Improvement of Performance and Reduction of Time.

    Science.gov (United States)

    Tennyson, Robert D.; Tennyson, Carol L.

    Three design strategies for selecting number of instructional instances needed in concept learning were investigated. Two strategies used adaptive procedures for the selection, while a nonadaptive strategy selected instances by number of associated attributes. The data analysis showed that the full adaptive strategy (using pretask and on-task…

  19. Designing Automated Adaptive Support to Improve Student Helping Behaviors in a Peer Tutoring Activity

    Science.gov (United States)

    Walker, Erin; Rummel, Nikol; Koedinger, Kenneth R.

    2011-01-01

    Adaptive collaborative learning support systems analyze student collaboration as it occurs and provide targeted assistance to the collaborators. Too little is known about how to design adaptive support to have a positive effect on interaction and learning. We investigated this problem in a reciprocal peer tutoring scenario, where two students take…

  20. Arbitrary visuo-motor mapping during object manipulation in mild cognitive impairment and Alzheimer's disease: a pilot study.

    Science.gov (United States)

    Ameli, Mitra; Kemper, Friederike; Sarfeld, Anna-Sophia; Kessler, Josef; Fink, Gereon R; Nowak, Dennis A

    2011-07-01

    Empirical evidence for an essential role of the hippocampal system in arbitrary visuo-motor mapping suggests that acquisition and retrieval of arbitrary visuo-motor mapping might be impaired in mild cognitive impairment (MCI) and Alzheimer's disease (AD). The present pilot study investigated whether MCI of amnestic type or AD impact upon the capacity to scale grip force in a predictive manner to the mass of an object to be lifted based on learned associations between arbitrary colour cues and mass. Patients with MCI (n=8) and AD (n=8) grasped and lifted two different masses (400g and 600g) in random order using a precision grip between index finger and thumb. In a "no cue" experiment, a non-informative neutral visual stimulus was presented prior to each lift, thereby disallowing any prediction about which of the two masses was going to be lifted in the next trial. In a "cue" experiment an arbitrary colour cue provided advance information about which of the two masses to be lifted. In the "no cue" condition patients scaled their grip force according to the mass of the preceding lift. In the "cue" experiment neither patients with amnestic MCI nor those with AD were able to adjust their grip force based on visuo-motor mappings with arbitrary colour cues. These preliminary data suggest that the hippocampal system plays an essential role for arbitrary visuo-motor mapping in the grip-lift task. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Adaptive statistical iterative reconstruction improves image quality without affecting perfusion CT quantitation in primary colorectal cancer

    Directory of Open Access Journals (Sweden)

    D. Prezzi

    Full Text Available Objectives: To determine the effect of Adaptive Statistical Iterative Reconstruction (ASIR on perfusion CT (pCT parameter quantitation and image quality in primary colorectal cancer. Methods: Prospective observational study. Following institutional review board approval and informed consent, 32 patients with colorectal adenocarcinoma underwent pCT (100 kV, 150 mA, 120 s acquisition, axial mode. Tumour regional blood flow (BF, blood volume (BV, mean transit time (MTT and permeability surface area product (PS were determined using identical regions-of-interests for ASIR percentages of 0%, 20%, 40%, 60%, 80% and 100%. Image noise, contrast-to-noise ratio (CNR and pCT parameters were assessed across ASIR percentages. Coefficients of variation (CV, repeated measures analysis of variance (rANOVA and Spearman’ rank order correlation were performed with statistical significance at 5%. Results: With increasing ASIR percentages, image noise decreased by 33% while CNR increased by 61%; peak tumour CNR was greater than 1.5 with 60% ASIR and above. Mean BF, BV, MTT and PS differed by less than 1.8%, 2.9%, 2.5% and 2.6% across ASIR percentages. CV were 4.9%, 4.2%, 3.3% and 7.9%; rANOVA P values: 0.85, 0.62, 0.02 and 0.81 respectively. Conclusions: ASIR improves image noise and CNR without altering pCT parameters substantially. Keywords: Perfusion imaging, Multidetector computed tomography, Colorectal neoplasms, Computer-assisted image processing, Radiation dosage

  2. Improvement of Navigation and Representation in Virtual Reality after Prism Adaptation in Neglect Patients

    Directory of Open Access Journals (Sweden)

    Bertrand Glize

    2017-11-01

    Full Text Available Prism adaptation (PA is responsible for an expansion of sensori-motor after-effects to cognitive domains for patients with spatial neglect. One important question is whether the cognitive after-effects induced by PA may also concern higher aspects of spatial cognition, such as navigation and topographic memory, which are critical in everyday life. The aim of this study was to assess whether multiple sessions of right PA can affect navigation and topographic memory. Seven right brain-damaged (RBD patients with chronic neglect were included. We used a virtual supermarket named VAP-S which is an original paradigm, similar to the “shopping list test” during which patients had to purchase items from a list of eight products. Furthermore, in order to assess generalization of PA effects on constructing a spatial map from virtual information, each participant was then asked to draw the map of the virtual supermarket from memory. Regarding navigation performance, significant results were obtained: session duration reduction, fewer numbers of pauses and omissions, more items purchased on the left side and more items purchased over all. A long-lasting effect was noted, up to one month after PA. The representational task performance was also significantly increased for map drawing, with a reduction of the right shift of the symmetry axis of the map, more items drawn on the left side of maps and over all, and more items correctly located on the map. Some of these effects lasted for at least 7 days. These results suggest an expansion of PA benefit to a virtual environment. Crucially, the cognitive benefits induced by PA were noted for complex spatial cognition tasks required in everyday life such as navigation and topographic memory and this improvement was maintained for up to 1 month.

  3. Improvement of Navigation and Representation in Virtual Reality after Prism Adaptation in Neglect Patients.

    Science.gov (United States)

    Glize, Bertrand; Lunven, Marine; Rossetti, Yves; Revol, Patrice; Jacquin-Courtois, Sophie; Klinger, Evelyne; Joseph, Pierre-Alain; Rode, Gilles

    2017-01-01

    Prism adaptation (PA) is responsible for an expansion of sensori-motor after-effects to cognitive domains for patients with spatial neglect. One important question is whether the cognitive after-effects induced by PA may also concern higher aspects of spatial cognition, such as navigation and topographic memory, which are critical in everyday life. The aim of this study was to assess whether multiple sessions of right PA can affect navigation and topographic memory. Seven right brain-damaged (RBD) patients with chronic neglect were included. We used a virtual supermarket named VAP-S which is an original paradigm, similar to the "shopping list test" during which patients had to purchase items from a list of eight products. Furthermore, in order to assess generalization of PA effects on constructing a spatial map from virtual information, each participant was then asked to draw the map of the virtual supermarket from memory. Regarding navigation performance, significant results were obtained: session duration reduction, fewer numbers of pauses and omissions, more items purchased on the left side and more items purchased over all. A long-lasting effect was noted, up to one month after PA. The representational task performance was also significantly increased for map drawing, with a reduction of the right shift of the symmetry axis of the map, more items drawn on the left side of maps and over all, and more items correctly located on the map. Some of these effects lasted for at least 7 days. These results suggest an expansion of PA benefit to a virtual environment. Crucially, the cognitive benefits induced by PA were noted for complex spatial cognition tasks required in everyday life such as navigation and topographic memory and this improvement was maintained for up to 1 month.

  4. INTRA-VARIETAL CROSSING AS METHOD TO IMPROVE ADAPTATION CHARACTERISTICS IN INITIAL BREEDING ACCESSIONS

    Directory of Open Access Journals (Sweden)

    E. A. Kozlovskaya

    2017-01-01

    Full Text Available The important goal of breeding program is to achieve the heterosis effect and develop the appropriate breeding lines to be used for crossing. The cultivation of the variety or breeding line for a long time and selection process under the same environmental factors lead to decrease of livability and productivity of the variety or breeding line. The intra-varietal and intra-line crossing is the method that enables to improve the genetic basis of the existing breeding accessions, when increasing the recombination ability, particular-ly among valuable and rare characteristics. The accessions of sweet pepper of different ecological origin: local varieties ‘Aeneas’, ‘Ivanhoe’ (Ukraine, ‘Sladkiy’ (Italy, breeding line ‘n 138d’ (Russia were taken to study the influence of intra-varietal crossing on recovery of combining ability in breeding lines. The progeny produced from intra-varietal crossing has been assessed for the fruit number, average fruit weight, yielding ability and marketability, and then consequently compared with control accession. As results showed the yielding ability had increased by 2.3-25.7%, depending on genotype, while the fruit weight had increased by 2-11%. Phenological observation showed that there is no significant difference at the phase of growing and development between control plants and plants produced through intra-varietal crossing. The detailed progeny assessment has revealed the different effect of adaptive ability among different plants when the plants crossing within the same accession. This enables to select the best accessions to be used in further heterosis breeding pro-gram.

  5. Improving Stability and Convergence for Adaptive Radial Basis Function Neural Networks Algorithm. (On-Line Harmonics Estimation Application

    Directory of Open Access Journals (Sweden)

    Eyad K Almaita

    2017-03-01

    Keywords: Energy efficiency, Power quality, Radial basis function, neural networks, adaptive, harmonic. Article History: Received Dec 15, 2016; Received in revised form Feb 2nd 2017; Accepted 13rd 2017; Available online How to Cite This Article: Almaita, E.K and Shawawreh J.Al (2017 Improving Stability and Convergence for Adaptive Radial Basis Function Neural Networks Algorithm (On-Line Harmonics Estimation Application.  International Journal of Renewable Energy Develeopment, 6(1, 9-17. http://dx.doi.org/10.14710/ijred.6.1.9-17

  6. THE INFLUENCE OF THE EXERCISES OF GROSS AND FINE MOTOR SKILLS ON VISUO-MOTOR COORDINATION OF THE CEREBRAL PALSY CHILDREN

    Directory of Open Access Journals (Sweden)

    Almira Mujkić

    2013-09-01

    Full Text Available Visuomotor coordination is reffered to eye coordination and to various parts of the body in different activities and games. The aim of the research was to establish the influence of the exercises of gross and fine motor skills on visuomotor coordination of the cerebral palsy children. The sample was the case study where a male person of 3 and a half years old was an examinee. Measuring instrument used was the Test of visuomotor coordination of the gross motor skills of the dominant hand. Data were analyzed by t-test.

  7. Improved covariance matrix estimation in spectrally inhomogeneous sea clutter with application to adaptive small boat detection.

    CSIR Research Space (South Africa)

    Herselman, PL

    2008-09-01

    Full Text Available Asymptotically optimal coherent detection techniques yield sub-clutter visibility in heavy-tailed sea clutter. The adaptive linear quadratic detector inherently assumes spectral homogeneity for the reference window of the covariance matrix estimator...

  8. Improving the Effectiveness of Speaker Verification Domain Adaptation With Inadequate In-Domain Data

    Science.gov (United States)

    2017-08-20

    verification scores. One such scoring method is probabilistic linear discriminant analysis (PLDA) [2], which provides a sta- tistical tool for...error rate (EER) and minimum decision cost function (mindcf), and pooled across gender . For all adaptation methods, an adaptation coefficient of α=0.5...Elder, “Probabilistic linear discriminant analysis for inferences about identity,” in ICCV, 2007. [3] D. Garcia-Romero and A. McCree, “Supervised domain

  9. Assessing the components of adaptive capacity to improve conservation and management efforts under global change

    Science.gov (United States)

    Nicotra, Adrienne; Beever, Erik; Robertson, Amanda; Hofmann, Gretchen; O’Leary, John

    2015-01-01

    Natural-resource managers and other conservation practitioners are under unprecedented pressure to categorize and quantify the vulnerability of natural systems based on assessment of the exposure, sensitivity, and adaptive capacity of species to climate change. Despite the urgent need for these assessments, neither the theoretical basis of adaptive capacity nor the practical issues underlying its quantification has been articulated in a manner that is directly applicable to natural-resource management. Both are critical for researchers, managers, and other conservation practitioners to develop reliable strategies for assessing adaptive capacity. Drawing from principles of classical and contemporary research and examples from terrestrial, marine, plant, and animal systems, we examined broadly the theory behind the concept of adaptive capacity. We then considered how interdisciplinary, trait- and triage-based approaches encompassing the oft-overlooked interactions among components of adaptive capacity can be used to identify species and populations likely to have higher (or lower) adaptive capacity. We identified the challenges and value of such endeavors and argue for a concerted interdisciplinary research approach that combines ecology, ecological genetics, and eco-physiology to reflect the interacting components of adaptive capacity. We aimed to provide a basis for constructive discussion between natural-resource managers and researchers, discussions urgently needed to identify research directions that will deliver answers to real-world questions facing resource managers, other conservation practitioners, and policy makers. Directing research to both seek general patterns and identify ways to facilitate adaptive capacity of key species and populations within species, will enable conservation ecologists and resource managers to maximize returns on research and management investment and arrive at novel and dynamic management and policy decisions.

  10. Assessing the components of adaptive capacity to improve conservation and management efforts under global change.

    Science.gov (United States)

    Nicotra, Adrienne B; Beever, Erik A; Robertson, Amanda L; Hofmann, Gretchen E; O'Leary, John

    2015-10-01

    Natural-resource managers and other conservation practitioners are under unprecedented pressure to categorize and quantify the vulnerability of natural systems based on assessment of the exposure, sensitivity, and adaptive capacity of species to climate change. Despite the urgent need for these assessments, neither the theoretical basis of adaptive capacity nor the practical issues underlying its quantification has been articulated in a manner that is directly applicable to natural-resource management. Both are critical for researchers, managers, and other conservation practitioners to develop reliable strategies for assessing adaptive capacity. Drawing from principles of classical and contemporary research and examples from terrestrial, marine, plant, and animal systems, we examined broadly the theory behind the concept of adaptive capacity. We then considered how interdisciplinary, trait- and triage-based approaches encompassing the oft-overlooked interactions among components of adaptive capacity can be used to identify species and populations likely to have higher (or lower) adaptive capacity. We identified the challenges and value of such endeavors and argue for a concerted interdisciplinary research approach that combines ecology, ecological genetics, and eco-physiology to reflect the interacting components of adaptive capacity. We aimed to provide a basis for constructive discussion between natural-resource managers and researchers, discussions urgently needed to identify research directions that will deliver answers to real-world questions facing resource managers, other conservation practitioners, and policy makers. Directing research to both seek general patterns and identify ways to facilitate adaptive capacity of key species and populations within species, will enable conservation ecologists and resource managers to maximize returns on research and management investment and arrive at novel and dynamic management and policy decisions. © 2015 Society for

  11. Highly undersampled MR image reconstruction using an improved dual-dictionary learning method with self-adaptive dictionaries.

    Science.gov (United States)

    Li, Jiansen; Song, Ying; Zhu, Zhen; Zhao, Jun

    2017-05-01

    Dual-dictionary learning (Dual-DL) method utilizes both a low-resolution dictionary and a high-resolution dictionary, which are co-trained for sparse coding and image updating, respectively. It can effectively exploit a priori knowledge regarding the typical structures, specific features, and local details of training sets images. The prior knowledge helps to improve the reconstruction quality greatly. This method has been successfully applied in magnetic resonance (MR) image reconstruction. However, it relies heavily on the training sets, and dictionaries are fixed and nonadaptive. In this research, we improve Dual-DL by using self-adaptive dictionaries. The low- and high-resolution dictionaries are updated correspondingly along with the image updating stage to ensure their self-adaptivity. The updated dictionaries incorporate both the prior information of the training sets and the test image directly. Both dictionaries feature improved adaptability. Experimental results demonstrate that the proposed method can efficiently and significantly improve the quality and robustness of MR image reconstruction.

  12. Rift Valley fever dynamics in Senegal: a project for pro-active adaptation and improvement of livestock raising management.

    Science.gov (United States)

    Lafaye, Murielle; Sall, Baba; Ndiaye, Youssou; Vignolles, Cecile; Tourre, Yves M; Borchi, Franc Ois; Soubeyroux, Jean-Michel; Diallo, Mawlouth; Dia, Ibrahima; Ba, Yamar; Faye, Abdoulaye; Ba, Taibou; Ka, Alioune; Ndione, Jacques-André; Gauthier, Hélène; Lacaux, Jean-Pierre

    2013-11-01

    The multi-disciplinary French project "Adaptation à la Fiévre de la Vallée du Rift" (AdaptFVR) has concluded a 10-year constructive interaction between many scientists/partners involved with the Rift Valley fever (RVF) dynamics in Senegal. The three targeted objectives reached were (i) to produce--in near real-time--validated risk maps for parked livestock exposed to RVF mosquitoes/vectors bites; (ii) to assess the impacts on RVF vectors from climate variability at different time-scales including climate change; and (iii) to isolate processes improving local livestock management and animal health. Based on these results, concrete, pro-active adaptive actions were taken on site, which led to the establishment of a RVF early warning system (RVFews). Bulletins were released in a timely fashion during the project, tested and validated in close collaboration with the local populations, i.e. the primary users. Among the strategic, adaptive methods developed, conducted and evaluated in terms of cost/benefit analyses are the larvicide campaigns and the coupled bio-mathematical (hydrological and entomological) model technologies, which are being transferred to the staff of the "Centre de Suivi Ecologique" (CSE) in Dakar during 2013. Based on the results from the AdaptFVR project, other projects with similar conceptual and modelling approaches are currently being implemented, e.g. for urban and rural malaria and dengue in the French Antilles.

  13. Rift Valley fever dynamics in Senegal: a project for pro-active adaptation and improvement of livestock raising management

    Directory of Open Access Journals (Sweden)

    Murielle Lafaye

    2013-11-01

    Full Text Available The multi-disciplinary French project “Adaptation à la Fièvre de la Vallée du Rift” (AdaptFVR has concluded a 10-year constructive interaction between many scientists/partners involved with the Rift Valley fever (RVF dynamics in Senegal. The three targeted objectives reached were (i to produce - in near real-time - validated risk maps for parked livestock exposed to RVF mosquitoes/vectors bites; (ii to assess the impacts on RVF vectors from climate variability at different time-scales including climate change; and (iii to isolate processes improving local livestock management and animal health. Based on these results, concrete, pro-active adaptive actions were taken on site, which led to the establishment of a RVF early warning system (RVFews. Bulletins were released in a timely fashion during the project, tested and validated in close collaboration with the local populations, i.e. the primary users. Among the strategic, adaptive methods developed, conducted and evaluated in terms of cost/benefit analyses are the larvicide campaigns and the coupled bio-mathematical (hydrological and entomological model technologies, which are being transferred to the staff of the “Centre de Suivi Ecologique” (CSE in Dakar during 2013. Based on the results from the AdaptFVR project, other projects with similar conceptual and modelling approaches are currently being implemented, e.g. for urban and rural malaria and dengue in the French Antilles.

  14. An Improved WiFi/PDR Integrated System Using an Adaptive and Robust Filter for Indoor Localization

    Directory of Open Access Journals (Sweden)

    Zengke Li

    2016-11-01

    Full Text Available Location-based services (LBS are services offered through a mobile device that take into account a device’s geographical location. To provide position information for these services, location is a key process. GNSS (Global Navigation Satellite System can provide sub-meter accuracy in open-sky areas using satellite signals. However, for indoor and dense urban environments, the accuracy deteriorates significantly because of weak signals and dense multipaths. The situation becomes worse in indoor environments where the GNSS signals are unreliable or totally blocked. To improve the accuracy of indoor positioning for location-based services, an improved WiFi/Pedestrian Dead Reckoning (PDR integrated positioning and navigation system using an adaptive and robust filter is presented. The adaptive filter is based on scenario and motion state recognition and the robust filter is based on the Mahalanobis distance. They are combined and used in the WiFi/PDR integrated system to weaken the effect of gross errors on the dynamic and observation models. To validate their performance in the WiFi/PDR integrated system, a real indoor localization experiment is conducted. The results indicate that the adaptive filter is better able to adapt to the circumstances of the dynamic model by adjusting the covariance of the process noise and the robust Kalman filter is able to mitigate the harmful effect of gross errors from the WiFi positioning.

  15. Image guided adaptive brachytherapy with combined intracavitary and interstitial technique improves the therapeutic ratio in locally advanced cervical cancer: Analysis from the retroEMBRACE study

    DEFF Research Database (Denmark)

    LU, Fokdal; Sturdza, Alina; Mazeron, Renaud

    2016-01-01

    Background and purpose Image guided adaptive brachytherapy (IGABT) using intracavitary applicators (IC) has led to a significant improvement of local control in locally advanced cervical cancer (LACC). Further improvement has been obtained with combined intracavitary/interstitial (IC...

  16. Rapid visuomotor processing of phobic images in spider- and snake-fearful participants.

    Science.gov (United States)

    Haberkamp, Anke; Schmidt, Filipp; Schmidt, Thomas

    2013-10-01

    This study investigates enhanced visuomotor processing of phobic compared to fear-relevant and neutral stimuli. We used a response priming design to measure rapid, automatic motor activation by natural images (spiders, snakes, mushrooms, and flowers) in spider-fearful, snake-fearful, and control participants. We found strong priming effects in all tasks and conditions; however, results showed marked differences between groups. Most importantly, in the group of spider-fearful individuals, spider pictures had a strong and specific influence on even the fastest motor responses: Phobic primes entailed the largest priming effects, and phobic targets accelerated responses, both effects indicating speeded response activation by phobic images. In snake-fearful participants, this processing enhancement for phobic material was less pronounced and extended to both snake and spider images. We conclude that spider phobia leads to enhanced processing capacity for phobic images. We argue that this is enabled by long-term perceptual learning processes. © 2013.

  17. Visuomotor priming of a manual reaching movement during a perceptual decision task.

    Science.gov (United States)

    Olivier, Gerard

    2006-12-08

    This paper deals with the mental simulation of manual movement that sometimes accompanies the visual perception of an object. Previous studies investigated how visual objects prime the grasping manual movement they afford. The principal purpose of the present experiment was to determine if such visuomotor priming also concerns the reaching manual movement that visual objects afford. During a perceptual decision task, 32 subjects were asked to grasp a proximal or distal switch, as fast and accurately as possible, depending on the color of a chess piece displayed on a computer screen. Results showed an effect on the reaction times of the interaction between the position of the chess piece on the chessboard and the manual response, suggesting that subjects mentally simulated a manual reaching movement toward the perceived chess piece.

  18. Inter- and Intrahemispheric EEG Coherence and Visuomotor Performance During Shooting Competition and Practice.

    Science.gov (United States)

    Woo, Minjung; Kim, Yujin

    2017-08-01

    This study compared inter- and intrahemispheric cortical networking and visuomotor performance during practice and competition in 14 air pistol athletes (mean age of 17.8 years). Participants self-reported their competitiveness, stress, confidence, and relaxation through visual analog scales; shooting score and aiming time were measured by the SCATT program. Inter- and intrahemispheric coherences during aiming were analyzed. Under competition following the practice condition, self-reported competitiveness and stress were higher, but confidence was lower. Aiming time during competition was longer than during practice; but there were no significant shooting score differences between conditions, perhaps due to only low-grade competitive anxiety. Through coherence analysis, interhemispheric coherence during aiming was higher under competition, relative to practice. Competitive anxiety seems to result in reduced neural efficiency and regional cortical autonomy, though there was no intrahemispheric electroencephalogram coherence difference between competition and practice conditions.

  19. Minimal Enteral Nutrition to Improve Adaptation After Intestinal Resection in Piglets and Infants

    DEFF Research Database (Denmark)

    Aunsholt, Lise; Qvist, Niels; Sangild, Per Torp

    2017-01-01

    , enteral colostrum supplementation was well tolerated, and no infants developed clinical signs of cow's milk allergy. CONCLUSION: Minimal enteral nutrition feeding with bovine colostrum and formula induced similar intestinal adaptation after resection in piglets. Colostrum was well tolerated by newly......BACKGROUND: Minimal enteral nutrition (MEN) may induce a diet-dependent stimulation of gut adaptation following intestinal resection. Bovine colostrum is rich in growth factors, and we hypothesized that MEN with colostrum would stimulate intestinal adaptation, compared with formula, and would...... be well tolerated in patients with short bowel syndrome. METHODS: In experiment 1, 3-day-old piglets with 50% distal small intestinal resection were fed parenteral nutrition (PN, n = 10) or PN plus MEN given as either colostrum (PN-COL, n = 5) or formula (PN-FORM, n = 9) for 7 days. Intestinal nutrient...

  20. Relationships between personality traits, resting serum hormones and visuomotor ability in male judokas

    Directory of Open Access Journals (Sweden)

    Zbigniew Obmiński

    2016-03-01

    Full Text Available [b]Introduction.[/b] The purpose of this research was to study the relationships between selected personality features, the speed and accuracy of visumotor ability and hormonal status in the blood of male judokas. [b]Materials and method. [/b]Forty-five male judokas whose body mass ranged from 66–100 kg were included in the study. Each one was examined once during a single annual competitive season lasting from March – October. The protocol of the study comprised five procedures carried out in the following order: (a capillary blood sampling in the morning (07:30, (b second capillary blood sampling directly prior to the personality examination, (c examination of the personality traits, (d testing of visuo-motor ability with the use of an electronic cross-shape electronic device, (e third capillary blood sampling after the entire study. The entire study started and ended in the morning. For each subject, the three serum samples were pooled and the levels of cortisol (C and testosterone (T were determined in the serum specimen. [b]Results.[/b] There were significant correlations among the scores in selected personality traits, anxiety (A, neuroticism (N, extraversion (E, perseveration (P, emotional reactivity (ER and achievement motivation (AM. The C level did not correlate with any variables, however, it did positively correlate with E and visuo-motor ability. There were inverse relationships between E and A, N, P and ER. [b]Conclusions.[/b] The study confirmed relationships in the androgenic status in circulation, personality traits and psycho-motor abilities.

  1. When eyes drive hand: Influence of non-biological motion on visuo-motor coupling.

    Science.gov (United States)

    Thoret, Etienne; Aramaki, Mitsuko; Bringoux, Lionel; Ystad, Sølvi; Kronland-Martinet, Richard

    2016-01-26

    Many studies stressed that the human movement execution but also the perception of motion are constrained by specific kinematics. For instance, it has been shown that the visuo-manual tracking of a spotlight was optimal when the spotlight motion complies with biological rules such as the so-called 1/3 power law, establishing the co-variation between the velocity and the trajectory curvature of the movement. The visual or kinesthetic perception of a geometry induced by motion has also been shown to be constrained by such biological rules. In the present study, we investigated whether the geometry induced by the visuo-motor coupling of biological movements was also constrained by the 1/3 power law under visual open loop control, i.e. without visual feedback of arm displacement. We showed that when someone was asked to synchronize a drawing movement with a visual spotlight following a circular shape, the geometry of the reproduced shape was fooled by visual kinematics that did not respect the 1/3 power law. In particular, elliptical shapes were reproduced when the circle is trailed with a kinematics corresponding to an ellipse. Moreover, the distortions observed here were larger than in the perceptual tasks stressing the role of motor attractors in such a visuo-motor coupling. Finally, by investigating the direct influence of visual kinematics on the motor reproduction, our result conciliates previous knowledge on sensorimotor coupling of biological motions with external stimuli and gives evidence to the amodal encoding of biological motion. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  2. Intense Training as a Means to Improve Running Performance in Trained Runners and the Adaptation of Muscle Tissue

    DEFF Research Database (Denmark)

    Skovgaard, Casper

    While many studies have documented the beneficial effect of intense training on performance, movement economy and muscular adaptations in trained subjects (reviewed in Iaia & Bangsbo 2010; J Bangsbo 2015; Hostrup & Bangsbo 2016), knowledge in certain areas are lacking. Examples on such areas...... compositions of intense training on performance, movement economy and muscular adaptations. The findings from the present PhD study suggest that performing intense training, in the form of speed endurance training (SET), for a relatively short period improves short and long-term performance. Both a prolonged...... and proteins related to Ca2+ re-uptake. The changes in 10-km performance were associated with improved running economy and anaerobic capacity, thereby blueprinting the relevance of intense training for long-term performance. Collectively, these findings indicate that short-term performance does continuously...

  3. Intense Training as a Means to Improve Running Performance in Trained Runners and the Adaptation of Muscle Tissue

    DEFF Research Database (Denmark)

    Skovgaard, Casper

    While many studies have documented the beneficial effect of intense training on performance, movement economy and muscular adaptations in trained subjects (reviewed in Iaia & Bangsbo 2010; J Bangsbo 2015; Hostrup & Bangsbo 2016), knowledge in certain areas are lacking. Examples on such areas...... compositions of intense training on performance, movement economy and muscular adaptations. The findings from the present PhD study suggest that performing intense training, in the form of speed endurance training (SET), for a relatively short period improves short and long-term performance. Both a prolonged...... and proteins related to Ca2+ re-uptake. The changes in 10-km performance were associated with improved running economy and anaerobic capacity, thereby blueprinting the relevance of intense training for long-term performance. Collectively, these findings indicate that short-term performance does continuously...

  4. Efficiency and reliability improvement in wind turbine converters by grid converter adaptive control

    DEFF Research Database (Denmark)

    Trintis, Ionut; Munk-Nielsen, Stig; Abrahamsen, Flemming

    2013-01-01

    This paper presents a control method that reduces the losses in wind turbine converters adaptively controlling the grid converter. The dc-link voltage adapts its reference based on the system state and therefore reduces the stored energy, and is therefore kept at the minimum necessary for the grid...... and generator side. Operating in this way, the electrical and thermal stress factors are decreased on the power electronic devices, increasing their lifetime. The simulation results using this method show efficiency increase and devices temperature cycles slightly decreased. Experimental results on a wind...... turbine power stack shows efficiency increase in the high power region....

  5. Adaptive e-learning to improve dietary behaviour: a systematic review and cost-effectiveness analysis.

    Science.gov (United States)

    Harris, J; Felix, L; Miners, A; Murray, E; Michie, S; Ferguson, E; Free, C; Lock, K; Landon, J; Edwards, P

    2011-10-01

    UK public health policy strongly advocates dietary change for the improvement of population health and emphasises the importance of individual empowerment to improve health. A new and evolving area in the promotion of dietary behavioural change is 'e-learning', the use of interactive electronic media to facilitate teaching and learning on a range of issues including health. The high level of accessibility, combined with emerging advances in computer processing power, data transmission and data storage, makes interactive e-learning a potentially powerful and cost-effective medium for improving dietary behaviour. This review aims to assess the effectiveness and cost-effectiveness of adaptive e-learning interventions for dietary behaviour change, and also to explore potential psychological mechanisms of action and components of effective interventions. Electronic bibliographic databases (Cumulative Index to Nursing and Allied Health Literature, The Cochrane Library, Dissertation Abstracts, EMBASE, Education Resources Information Center, Global Health, Health Economic Evaluations Database, Health Management Information Consortium, MEDLINE, PsycINFO and Web of Science) were searched for the period January 1990 to November 2009. Reference lists of included studies and previous reviews were also screened; authors were contacted and trial registers were searched. Studies were included if they were randomised controlled trials, involving participants aged ≥ 13 years, which evaluated the effectiveness of interactive software programs for improving dietary behaviour. Primary outcomes were measures of dietary behaviours, including estimated intakes or changes in intake of energy, nutrients, dietary fibre, foods or food groups. Secondary outcome measures were clinical outcomes such as anthropometry or blood biochemistry. Psychological mediators of dietary behaviour change were also investigated. Two review authors independently screened results and extracted data from

  6. Improving the role of vulnerability assessments In decision support for effective climate adaptation

    Science.gov (United States)

    Linda A. Joyce; Constance I. Millar

    2014-01-01

    Vulnerability assessments (VA) have been proposed as an initial step in a process to develop and implement adaptation management for climate change in forest ecosystems. Scientific understanding of the effects of climate change is an ever-accumulating knowledge base. Synthesizing information from this knowledge base in the context of our understanding of ecosystem...

  7. The Contextualized Technology Adaptation Process (CTAP): Optimizing Health Information Technology to Improve Mental Health Systems

    Science.gov (United States)

    Lyon, Aaron R.; Wasse, Jessica Knaster; Ludwig, Kristy; Zachry, Mark; Bruns, Eric J.; Unützer, Jürgen; McCauley, Elizabeth

    2015-01-01

    Health information technologies have become a central fixture in the mental healthcare landscape, but few frameworks exist to guide their adaptation to novel settings. This paper introduces the Contextualized Technology Adaptation Process (CTAP) and presents data collected during Phase 1 of its application to measurement feedback system development in school mental health. The CTAP is built on models of human-centered design and implementation science and incorporates repeated mixed methods assessments to guide the design of technologies to ensure high compatibility with a destination setting. CTAP phases include: (1) Contextual evaluation, (2) Evaluation of the unadapted technology, (3) Trialing and evaluation of the adapted technology, (4) Refinement and larger-scale implementation, and (5) Sustainment through ongoing evaluation and system revision. Qualitative findings from school-based practitioner focus groups are presented, which provided information for CTAP Phase 1, contextual evaluation, surrounding education sector clinicians’ workflows, types of technologies currently available, and influences on technology use. Discussion focuses on how findings will inform subsequent CTAP phases, as well as their implications for future technology adaptation across content domains and service sectors. PMID:25677251

  8. Building Turnaround Capacity for Urban School Improvement: The Role of Adaptive Leadership and Defined Autonomy

    Science.gov (United States)

    Conrad, Jill K.

    2013-01-01

    This dissertation examines the levels of and relationships between technical leadership, adaptive leadership, and defined autonomy among Denver school leaders along with their combined effects on school growth gains over time. Thirty principals provided complete responses to an online survey that included existing scales for technical leadership,…

  9. Dancing Aerobics as Means of Improving Adaptive Possibilities of Foreign Female Students

    Directory of Open Access Journals (Sweden)

    S Yu Razmakhova

    2014-12-01

    Full Text Available The problem of modeling training sessions of health aerobic classes in international higher schools is quite topical. The proposed form of training helps to speed up the adaptive responses of foreign students in the new conditions of their life and the implementation of the goals of internationalization.

  10. Analysis of revenue improvements with runtime adaptation of service composition based on conditional request retries

    NARCIS (Netherlands)

    Zivkovic, Miroslav; van den Berg, Hans Leo

    In this paper we consider the runtime service adaptation mechanism for service compositions that is based on conditional retries. A single retry may be issued while a concrete service within composition is executed. This retry could either invoke the same concrete service or a functionally

  11. Investigating Purposeful Science Curriculum Adaptation as a Strategy to Improve Teaching and Learning

    Science.gov (United States)

    Debarger, Angela Haydel; Penuel, William R.; Moorthy, Savitha; Beauvineau, Yves; Kennedy, Cathleen A.; Boscardin, Christy Kim

    2017-01-01

    In this paper, we investigate the potential and conditions for using curriculum adaptation to support reform of science teaching and learning. With each wave of reform in science education, curriculum has played a central role and the contemporary wave focused on implementation of the principles and vision of the "Framework for K-12 Science…

  12. Improving Adaptive Importance Sampling Simulation of Markovian Queueing Models using Non-parametric Smoothing

    NARCIS (Netherlands)

    Woudt, Edwin; de Boer, Pieter-Tjerk; van Ommeren, Jan C.W.

    2007-01-01

    Previous work on state-dependent adaptive importance sampling techniques for the simulation of rare events in Markovian queueing models used either no smoothing or a parametric smoothing technique, which was known to be non-optimal. In this paper, we introduce the use of kernel smoothing in this

  13. Improving the Stability of the LMF Adaptive Algorithm Using the Median Filteer

    DEFF Research Database (Denmark)

    Bysted, Tommy Kristensen; Rusu, Corneliu

    1998-01-01

    environments and secondly it enables the use of larger step-size of the adaptive algorithm especially when the signals are corrupted by noise. The disadvantages are a small raise in the computational complexity and slower convergence than the LMF. Two examples are given which illustrates the behavior...

  14. Integration of auto-steering with adaptive cruise control for improved cornering behaviour

    NARCIS (Netherlands)

    Idriz, Adem; Abdul Rachman, Arya Senna; Baldi, S.

    2017-01-01

    Several works have proposed longitudinal control strategies enabling a vehicle to operate adaptive cruise control and collision avoidance functions. However, no integration with lateral control has been proposed in the current state of the art,
    which motivates the developments of this work. This

  15. Functional near-infrared spectroscopy-based correlates of prefrontal cortical dynamics during a cognitive-motor executive adaptation task

    Directory of Open Access Journals (Sweden)

    Rodolphe J. Gentili

    2013-07-01

    Full Text Available This study investigated changes in brain hemodynamics, as measured by functional near infrared spectroscopy (fNIR, during performance of a cognitive-motor adaptation task. The adaptation task involved the learning of a novel visuo-motor transformation (a 60 degree counterclockwise screen-cursor rotation, which required inhibition of a pre-potent visuo-motor response. A control group experienced a familiar transformation and thus, did not face any executive challenge. Analysis of the experimental group hemodynamic responses revealed that the performance enhancement was associated with a monotonic reduction in the oxygenation level in the prefrontal cortex. This finding confirms and extends functional magnetic resonance imaging (fMRI and electroencephalography (EEG studies of visuo-motor adaptation and learning. The changes in prefrontal brain activation suggest an initial recruitment of frontal executive functioning to inhibit pre-potent visuo-motor mappings followed by a progressive de-recruitment of the same prefrontal regions. The prefrontal hemodynamic changes observed in the experimental group translated into enhanced motor performance revealed by a reduction in movement time, movement extent, root mean square error and the directional error. These kinematic adaptations are consistent with the acquisition of an internal model of the novel visuo-motor transformation. No comparable change was observed in the control group for either the hemodynamics or for the kinematics. This study 1 extends our understanding of the frontal executive processes from the cognitive to the cognitive-motor domain and 2 suggests that optical brain imaging can be employed to provide hemodynamic based-biomarkers to assess and monitor the level of adaptive cognitive-motor performance.

  16. Improved methods in neural network-based adaptive output feedback control, with applications to flight control

    Science.gov (United States)

    Kim, Nakwan

    Utilizing the universal approximation property of neural networks, we develop several novel approaches to neural network-based adaptive output feedback control of nonlinear systems, and illustrate these approaches for several flight control applications. In particular, we address the problem of non-affine systems and eliminate the fixed point assumption present in earlier work. All of the stability proofs are carried out in a form that eliminates an algebraic loop in the neural network implementation. An approximate input/output feedback linearizing controller is augmented with a neural network using input/output sequences of the uncertain system. These approaches permit adaptation to both parametric uncertainty and unmodeled dynamics. All physical systems also have control position and rate limits, which may either deteriorate performance or cause instability for a sufficiently high control bandwidth. Here we apply a method for protecting an adaptive process from the effects of input saturation and time delays, known as "pseudo control hedging". This method was originally developed for the state feedback case, and we provide a stability analysis that extends its domain of applicability to the case of output feedback. The approach is illustrated by the design of a pitch-attitude flight control system for a linearized model of an R-50 experimental helicopter, and by the design of a pitch-rate control system for a 58-state model of a flexible aircraft consisting of rigid body dynamics coupled with actuator and flexible modes. A new approach to augmentation of an existing linear controller is introduced. It is especially useful when there is limited information concerning the plant model, and the existing controller. The approach is applied to the design of an adaptive autopilot for a guided munition. Design of a neural network adaptive control that ensures asymptotically stable tracking performance is also addressed.

  17. Is it me or not me? Modulation of perceptual-motor awareness and visuomotor performance by mindfulness meditation

    Directory of Open Access Journals (Sweden)

    Naranjo José

    2012-07-01

    Full Text Available Abstract Background Attribution of agency involves the ability to distinguish our own actions and their sensory consequences which are self-generated from those generated by external agents. There are several pathological cases in which motor awareness is dramatically impaired. On the other hand, awareness-enhancement practices like tai-chi and yoga are shown to improve perceptual-motor awareness. Meditation is known to have positive impacts on perception, attention and consciousness itself, but it is still unclear how meditation changes sensorimotor integration processes and awareness of action. The aim of this study was to investigate how visuomotor performance and self-agency is modulated by mindfulness meditation. This was done by studying meditators’ performance during a conflicting reaching task, where the congruency between actions and their consequences is gradually altered. This task was presented to novices in meditation before and after an intensive 8 weeks mindfulness meditation training (MBSR. The data of this sample was compared to a group of long-term meditators and a group of healthy non-meditators. Results Mindfulness resulted in a significant improvement in motor control during perceptual-motor conflict in both groups. Novices in mindfulness demonstrated a strongly increased sensitivity to detect external perturbation after the MBSR intervention. Both mindfulness groups demonstrated a speed/accuracy trade-off in comparison to their respective controls. This resulted in slower and more accurate movements. Conclusions Our results suggest that mindfulness meditation practice is associated with slower body movements which in turn may lead to an increase in monitoring of body states and optimized re-adjustment of movement trajectory, and consequently to better motor performance. This extended conscious monitoring of perceptual and motor cues may explain how, while dealing with perceptual-motor conflict, improvement in motor

  18. Adaptive control algorithm for improving power capture of wind turbines in turbulent winds

    DEFF Research Database (Denmark)

    Diaz-Guerra, Lluis; Adegas, Fabiano Daher; Stoustrup, Jakob

    2012-01-01

    , the complex and time-varying aerodynamics a WT face due to turbulent winds make their determination a hard task. The selected constant parameters may maximize energy for a particular, but not all, wind regime conditions. Adaptivity can modify the controller to increase power capture under variable wind...... conditions. This paper present new analysis tools and an adaptive control law to increase the energy captured by a wind turbine. Due to its simplicity, it can be easily added to existing industry-standard controllers. The effectiveness of the proposed algorithm is assessed by simulations on a high......The standard wind turbine (WT) control law modifies the torque applied to the generator as a quadratic function of the generator speed (K!2) while blades are positioned at some optimal pitch angle (). The value of K and should be properly selected such that energy capture is increased. In practice...

  19. Improving Energy Efficiency of an Autonomous Bicycle with Adaptive Controller Design

    Directory of Open Access Journals (Sweden)

    David Rodriguez-Rosa

    2017-05-01

    Full Text Available A method is proposed to achieve lateral stability of an autonomous bicycle with only the rotation of the front wheel. This can be achieved with a classic controller. However, if the energy consumption of the bicycle also has to be minimized, this solution is not valid. To solve this problem, an adaptive controller has been designed, which modifies its gains according to the bicycle’s forward velocity, adapting its response with minimum energy consumption and satisfying the design specifications. The study demonstrates the efficiency of the proposed control, achieving an energy saving of 73 . 8 % in trajectory tracking with respect to a conventional proportional-integral ( P I controller. These results show the importance of designing energy-efficient controllers, not only for autonomous vehicles but also for any automatic system where the energy consumption can be minimized.

  20. Adaptive statistical iterative reconstruction improves image quality without affecting perfusion CT quantitation in primary colorectal cancer

    OpenAIRE

    Prezzi, Davide; Goh, V.; Virdi, S.; Mallett, S; Grierson, C; Breen, D.J.

    2017-01-01

    Objectives: To determine the effect of Adaptive Statistical Iterative Reconstruction (ASIR) on perfusion CT (pCT) parameter quantitation and image quality in primary colorectal cancer. Methods: Prospective observational study. Following institutional review board approval and informed consent, 32 patients with colorectal adenocarcinoma underwent pCT (100 kV, 150 mA, 120 s acquisition, axial mode). Tumour regional blood flow (BF), blood volume (BV), mean transit time (MTT) and permeability sur...

  1. Studying citizen science through adaptive management and learning feedbacks as mechanisms for improving conservation.

    Science.gov (United States)

    Jordan, Rebecca; Gray, Steven; Sorensen, Amanda; Newman, Greg; Mellor, David; Newman, Greg; Hmelo-Silver, Cindy; LaDeau, Shannon; Biehler, Dawn; Crall, Alycia

    2016-06-01

    Citizen science has generated a growing interest among scientists and community groups, and citizen science programs have been created specifically for conservation. We examined collaborative science, a highly interactive form of citizen science, which we developed within a theoretically informed framework. In this essay, we focused on 2 aspects of our framework: social learning and adaptive management. Social learning, in contrast to individual-based learning, stresses collaborative and generative insight making and is well-suited for adaptive management. Adaptive-management integrates feedback loops that are informed by what is learned and is guided by iterative decision making. Participants engaged in citizen science are able to add to what they are learning through primary data collection, which can result in the real-time information that is often necessary for conservation. Our work is particularly timely because research publications consistently report a lack of established frameworks and evaluation plans to address the extent of conservation outcomes in citizen science. To illustrate how our framework supports conservation through citizen science, we examined how 2 programs enacted our collaborative science framework. Further, we inspected preliminary conservation outcomes of our case-study programs. These programs, despite their recent implementation, are demonstrating promise with regard to positive conservation outcomes. To date, they are independently earning funds to support research, earning buy-in from local partners to engage in experimentation, and, in the absence of leading scientists, are collecting data to test ideas. We argue that this success is due to citizen scientists being organized around local issues and engaging in iterative, collaborative, and adaptive learning. © 2016 Society for Conservation Biology.

  2. Improving link prediction in complex networks by adaptively exploiting multiple structural features of networks

    Science.gov (United States)

    Ma, Chuang; Bao, Zhong-Kui; Zhang, Hai-Feng

    2017-10-01

    So far, many network-structure-based link prediction methods have been proposed. However, these methods only highlight one or two structural features of networks, and then use the methods to predict missing links in different networks. The performances of these existing methods are not always satisfied in all cases since each network has its unique underlying structural features. In this paper, by analyzing different real networks, we find that the structural features of different networks are remarkably different. In particular, even in the same network, their inner structural features are utterly different. Therefore, more structural features should be considered. However, owing to the remarkably different structural features, the contributions of different features are hard to be given in advance. Inspired by these facts, an adaptive fusion model regarding link prediction is proposed to incorporate multiple structural features. In the model, a logistic function combing multiple structural features is defined, then the weight of each feature in the logistic function is adaptively determined by exploiting the known structure information. Last, we use the "learnt" logistic function to predict the connection probabilities of missing links. According to our experimental results, we find that the performance of our adaptive fusion model is better than many similarity indices.

  3. Opportunities to Improve Urban and Ecosystem Adaptation to Climate Change Through Conservation of Green Space.

    Science.gov (United States)

    Heller, N. E.

    2014-12-01

    The conservation of biotic communities in urbanized ecosystems is critical in light of heightened vulnerability due to climate change. Conservation of large open spaces around cities and smaller 'green' spaces within cities - such as forest patches and wetlands - has the capacity to diminish the vulnerability of human communities to higher temperatures, water shortages, increased flooding and other impacts of climate change. In addition, native species need to migrate to track their climate niches and the chances of successful migration will be increased if species have access to habitat throughout the landscape. Thus there is a strong rationale to do more conservation and restoration for both ecosystem and urban adaptation to climate change. Despite this alignment, planning efforts in the urban and ecosystem sectors are rarely done synergistically. As a result it is not clear how well plans will achieve biodiversity along with other ecosystem services goals. In this talk, I will discuss how urban adaptation planning can better align with ecosystem adaptation planning by drawing on research exploring sustainability plans and urban ecology in US cities, including work conducted in the San Francisco Bay Area by the Terrestrial Biodiversity and Climate Change Collaborative (TBC3). This research shows that there are considerable opportunities for linking agendas across sectors in ways that could yield multiple benefits. There are however both social and ecological challenges. In some cases difficult choices will need to be made about which values and services are most important, or where in the landscape different values should be prioritized.

  4. A Novel Clinical Decision Support System Using Improved Adaptive Genetic Algorithm for the Assessment of Fetal Well-Being

    Directory of Open Access Journals (Sweden)

    Sindhu Ravindran

    2015-01-01

    Full Text Available A novel clinical decision support system is proposed in this paper for evaluating the fetal well-being from the cardiotocogram (CTG dataset through an Improved Adaptive Genetic Algorithm (IAGA and Extreme Learning Machine (ELM. IAGA employs a new scaling technique (called sigma scaling to avoid premature convergence and applies adaptive crossover and mutation techniques with masking concepts to enhance population diversity. Also, this search algorithm utilizes three different fitness functions (two single objective fitness functions and multi-objective fitness function to assess its performance. The classification results unfold that promising classification accuracy of 94% is obtained with an optimal feature subset using IAGA. Also, the classification results are compared with those of other Feature Reduction techniques to substantiate its exhaustive search towards the global optimum. Besides, five other benchmark datasets are used to gauge the strength of the proposed IAGA algorithm.

  5. Adaptive step size LMS improves ECG detection during MRI at 1.5 and 3 T.

    Science.gov (United States)

    Guillou, André; Sellal, Jean-Marc; Ménétré, Sarah; Petitmangin, Grégory; Felblinger, Jacques; Bonnemains, Laurent

    2017-12-01

    We describe a new real-time filter to reduce artefacts on electrocardiogram (ECG) due to magnetic field gradients during MRI. The proposed filter is a least mean square (LMS) filter able to continuously adapt its step size according to the gradient signal of the ongoing MRI acquisition. We implemented this filter and compared it, within two databases (at 1.5 and 3 T) with over 6000 QRS complexes, to five real-time filtering strategies (no filter, low pass filter, standard LMS, and two other filters optimized within the databases: optimized LMS, and optimized Kalman filter). The energy of the remaining noise was significantly reduced (26 vs. 68%, p Kalman filter, and 11% with optimized LMS filter. The adaptive step size LMS improves ECG denoising during MRI. QRS detection has the same F1 score with this filter than with filters optimized within the database.

  6. Intense Training as a Means to Improve Running Performance in Trained Runners and the Adaptation of Muscle Tissue

    DEFF Research Database (Denmark)

    Skovgaard, Casper

    While many studies have documented the beneficial effect of intense training on performance, movement economy and muscular adaptations in trained subjects (reviewed in Iaia & Bangsbo 2010; J Bangsbo 2015; Hostrup & Bangsbo 2016), knowledge in certain areas are lacking. Examples on such areas...... are the effect of: intense training for a prolonged period, intense training performed very frequently, reduced training volume after a period with frequent intense training, and repeating a period of intense training. Thus, the overall aim of this PhD project was to investigate the effect of different...... compositions of intense training on performance, movement economy and muscular adaptations. The findings from the present PhD study suggest that performing intense training, in the form of speed endurance training (SET), for a relatively short period improves short and long-term performance. Both a prolonged...

  7. Attention for action? Examining the link between attention and visuomotor control deficits in a patient with optic ataxia.

    Science.gov (United States)

    Striemer, Christopher; Locklin, Jason; Blangero, Annabelle; Rossetti, Yves; Pisella, Laure; Danckert, James

    2009-05-01

    The classic definition of 'pure' optic ataxia suggests that these patients' visuomotor impairments are independent of perceptual or attentional deficits. More recent work suggests that some patients with optic ataxia also have difficulty attending to targets in their ataxic field. Thus, an important question is whether these attentional deficits might be related to the well-known problems in visuomotor control evident in these patients. To investigate this question we had controls (N=5) and CF, a patient with optic ataxia in his left visual field, perform tasks that required them to detect or reach towards targets presented in either central vision, or at different target eccentricities in the periphery. As expected, CF was less accurate than controls when reaching to targets in his ataxic (left) visual field, and was much slower than controls to detect the presence of targets in his ataxic field. The reaction times to lift the hand in the pointing and the detecting conditions were correlated in the ataxic field of patient CF, suggesting a common attentional deficit in both tasks. Importantly, although CF was slower to detect targets in the ataxic field, and less accurate to reach towards those same targets, the two deficits did not follow the same pattern. Specifically, only reaching errors in the ataxic field were strongly modulated by target eccentricity. These results suggest that dorsal posterior parietal lesions result in attention and visuomotor control problems in optic ataxia that arise from damage to independent mechanisms.

  8. Improving Performance of Computer-aided Detection of Subtle Breast Masses Using an Adaptive Cueing Method

    Science.gov (United States)

    Wang, Xingwei; Li, Lihua; Xu, Weidong; Liu, Wei; Lederman, Dror; Zheng, Bin

    2012-01-01

    Current computer-aided detection (CAD) schemes for detecting mammographic masses have several limitations including high correlation with radiologists’ detection and cueing most subtle masses only on one view. To increase CAD sensitivity in cueing more subtle masses that are likely missed and/or overlooked by radiologists without increasing false-positive rates, we investigated a new case-dependent cueing method by combining the original CAD-generated detection scores with a computed bilateral mammographic density asymmetry index. Using the new method, we adaptively raise CAD-generated scores of regions detected on “high-risk” cases to cue more subtle mass regions and reduce CAD scores of regions detected on “low-risk” cases to discard more false-positive regions. A testing dataset involving 78 positive and 338 negative cases was used to test this adaptive cueing method. Each positive case involves two sequential examinations in which the mass was detected in “current” examination and missed in “prior” examination but detected in a retrospective review by radiologists. Applying to this dataset, a pre-optimized CAD scheme yielded 75% case-based and 55% region-based sensitivity on “current” examinations at a false-positive rate of 0.25 per image. CAD sensitivity was reduced to 42% (case-based) and 27% (region-based) on “prior” examinations. Using the new cueing method, case-based and region-based sensitivity could maximally increase 9% and 33% on the “prior” examinations, respectively. The percentages of the masses cued on two views also increased from 27% to 65%. The study demonstrated that using this adaptive cueing method enabled to help CAD cue more subtle cancers without increasing false-positive cueing rate. PMID:22218075

  9. Motor adaptation and generalization of reaching movements using motor primitives based on spatial coordinates

    Science.gov (United States)

    Sejnowski, Terrence J.

    2014-01-01

    The brain processes sensory and motor information in a wide range of coordinate systems, ranging from retinal coordinates in vision to body-centered coordinates in areas that control musculature. Here we focus on the coordinate system used in the motor cortex to guide actions and examine physiological and psychophysical evidence for an allocentric reference frame based on spatial coordinates. When the equations of motion governing reaching dynamics are expressed as spatial vectors, each term is a vector cross product between a limb-segment position and a velocity or acceleration. We extend this computational framework to motor adaptation, in which the cross-product terms form adaptive bases for canceling imposed perturbations. Coefficients of the velocity- and acceleration-dependent cross products are assumed to undergo plastic changes to compensate the force-field or visuomotor perturbations. Consistent with experimental findings, each of the cross products had a distinct reference frame, which predicted how an acquired remapping generalized to untrained location in the workspace. In response to force field or visual rotation, mainly the coefficients of the velocity- or acceleration-dependent cross products adapted, leading to transfer in an intrinsic or extrinsic reference frame, respectively. The model further predicted that remapping of visuomotor rotation should under- or overgeneralize in a distal or proximal workspace. The cross-product bases can explain the distinct patterns of generalization in visuomotor and force-field adaptation in a unified way, showing that kinematic and dynamic motor adaptation need not arise through separate neural substrates. PMID:25429111

  10. Differences in context and feedback result in different trajectories and adaptation strategies in reaching.

    Directory of Open Access Journals (Sweden)

    Fritzie Arce

    Full Text Available Computational models of motor control have often explained the straightness of horizontal planar reaching movements as a consequence of optimal control. Departure from rectilinearity is thus regarded as sub-optimal. Here we examine if subjects may instead select to make curved trajectories following adaptation to force fields and visuomotor rotations. Separate subjects adapted to force fields with or without visual feedback of their hand trajectory and were retested after 24 hours. Following adaptation, comparable accuracies were achieved in two ways: with visual feedback, adapted trajectories in force fields were straight whereas without it, they remained curved. The results suggest that trajectory shape is not always straight, but is also influenced by the calibration of available feedback signals for the state estimation required by the task. In a follow-up experiment, where additional subjects learned a visuomotor rotation immediately after force field, the trajectories learned in force fields (straight or curved were transferred when directions of the perturbations were similar but not when directions were opposing. This demonstrates a strong bias by prior experience to keep using a recently acquired control policy that continues to produce successful performance inspite of differences in tasks and feedback conditions. On relearning of force fields on the second day, facilitation by intervening visuomotor rotations occurred only when required motor adjustments and calibration of feedback signals were similar in both tasks. These results suggest that both the available feedback signals and prior history of learning influence the choice and maintenance of control policy during adaptations.

  11. Context-based service adaptation platform: Improving the user experience towards mobile location services

    DEFF Research Database (Denmark)

    Schou, Saowanee

    2008-01-01

    Back in 2000 and the, following two or three years, mobile location services gained a great deal of interest and they were considered as one of the few service categories where users would be willing to pay for the usage. Since 2000 countless mobile location services have been launched in different...... parts of the world. However, the mobile location services have obviously not yet met the hyped expectation of mass-market adoption that was expressed in 2000. The lack of adaptability and offerings tailored to different user requirements in specific contexts of use is one of the factors inhibiting...

  12. Improved prediction error filters for adaptive feedback cancellation in hearing aids

    DEFF Research Database (Denmark)

    Ngo, Kim; van Waterschoot, Toon; Christensen, Mads Græsbøll

    2013-01-01

    and the loudspeaker signal caused by the closed signal loop, in particular when the near-end signal is spectrally colored as is the case for a speech signal. This paper adopts a prediction-error method (PEM)-based approach to AFC, which is based on the use of decorrelating prediction error filters (PEFs). We propose......Acoustic feedback is a well-known problem in hearing aids, caused by the undesired acoustic coupling between the hearing aid loudspeaker and microphone. Acoustic feedback produces annoying howling sounds and limits the maximum achievable hearing aid amplification. This paper is focused on adaptive...

  13. Improving the response of accelerometers for automotive applications by using LMS adaptive filters.

    Science.gov (United States)

    Hernandez, Wilmar; de Vicente, Jesús; Sergiyenko, Oleg; Fernández, Eduardo

    2010-01-01

    In this paper, the least-mean-squares (LMS) algorithm was used to eliminate noise corrupting the important information coming from a piezoresisitive accelerometer for automotive applications. This kind of accelerometer is designed to be easily mounted in hard to reach places on vehicles under test, and they usually feature ranges from 50 to 2,000 g (where is the gravitational acceleration, 9.81 m/s(2)) and frequency responses to 3,000 Hz or higher, with DC response, durable cables, reliable performance and relatively low cost. However, here we show that the response of the sensor under test had a lot of noise and we carried out the signal processing stage by using both conventional and optimal adaptive filtering. Usually, designers have to build their specific analog and digital signal processing circuits, and this fact increases considerably the cost of the entire sensor system and the results are not always satisfactory, because the relevant signal is sometimes buried in a broad-band noise background where the unwanted information and the relevant signal sometimes share a very similar frequency band. Thus, in order to deal with this problem, here we used the LMS adaptive filtering algorithm and compare it with others based on the kind of filters that are typically used for automotive applications. The experimental results are satisfactory.

  14. Improve earthquake hypocenter using adaptive simulated annealing inversion in regional tectonic, volcano tectonic, and geothermal observation

    Energy Technology Data Exchange (ETDEWEB)

    Ry, Rexha Verdhora, E-mail: rexha.vry@gmail.com [Master Program of Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Jalan Ganesha No.10, Bandung 40132 (Indonesia); Nugraha, Andri Dian, E-mail: nugraha@gf.itb.ac.id [Global Geophysical Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Jalan Ganesha No.10, Bandung 40132 (Indonesia)

    2015-04-24

    Observation of earthquakes is routinely used widely in tectonic activity observation, and also in local scale such as volcano tectonic and geothermal activity observation. It is necessary for determining the location of precise hypocenter which the process involves finding a hypocenter location that has minimum error between the observed and the calculated travel times. When solving this nonlinear inverse problem, simulated annealing inversion method can be applied to such global optimization problems, which the convergence of its solution is independent of the initial model. In this study, we developed own program codeby applying adaptive simulated annealing inversion in Matlab environment. We applied this method to determine earthquake hypocenter using several data cases which are regional tectonic, volcano tectonic, and geothermal field. The travel times were calculated using ray tracing shooting method. We then compared its results with the results using Geiger’s method to analyze its reliability. Our results show hypocenter location has smaller RMS error compared to the Geiger’s result that can be statistically associated with better solution. The hypocenter of earthquakes also well correlated with geological structure in the study area. Werecommend using adaptive simulated annealing inversion to relocate hypocenter location in purpose to get precise and accurate earthquake location.

  15. Adaptive evolution of nontransgenic Escherichia coli KC01 for improved ethanol tolerance and homoethanol fermentation from xylose.

    Science.gov (United States)

    Wang, Yongze; Manow, Ryan; Finan, Christopher; Wang, Jinhua; Garza, Erin; Zhou, Shengde

    2011-09-01

    Due to its excellent capability to ferment five-carbon sugars, Escherichia coli has been considered one of the platform organisms to be engineered for production of cellulosic ethanol. Nevertheless, genetically engineered ethanologenic E. coli lacks the essential trait of alcohol tolerance. Development of ethanol tolerance is required for cost-effective ethanol fermentation. In this study, we improved alcohol tolerance of a nontransgenic E. coli KC01 (ldhA pflB ackA frdBC pdhR::pflBp6-aceEF-lpd) through adaptive evolution. During ~350 generations of adaptive evolution, a gradually increased concentration of ethanol was used as a selection pressure to enrich ethanol-tolerant mutants. The evolved mutant, E. coli SZ470, was able to grow anaerobically at 40 g l(-1) ethanol, a twofold improvement over parent KC01. When compared with KC01 for small-scale (500 ml) xylose (50 g l(-1)) fermentation, SZ470 achieved 67% higher cell mass, 48% faster volumetric ethanol productivity, and 50% shorter time to complete fermentation with ethanol titer of 23.5 g l(-1) and yield of 94%. These results demonstrate that an industry-oriented nontransgenic E. coli strain could be developed through incremental improvements of desired traits by a combination of molecular biology and traditional microbiology techniques.

  16. Improved formulations and an Adaptive Large Neighborhood Search heuristic for the integrated berth allocation and quay crane assignment problem

    DEFF Research Database (Denmark)

    Iris, Cagatay; Pacino, Dario; Røpke, Stefan

    2017-01-01

    This paper focuses on the integrated berth allocation and quay crane assignment problem in container terminals. We consider the decrease in the marginal productivity of quay cranes and the increase in handling time due to deviation from the desired position. We consider a continuous berth......, discretized in small equal-sized sections. A number of enhancements over the state-of-the-art formulation and an Adaptive Large Neighborhood Search (ALNS) heuristic are presented. Computational results reveal that the enhancements improve many of the best-known bounds, and the ALNS outperforms the state-of-the-art...

  17. Interleaved diffusion-weighted EPI improved by adaptive partial-Fourier and multi-band multiplexed sensitivity-encoding reconstruction

    Science.gov (United States)

    Chang, Hing-Chiu; Guhaniyogi, Shayan; Chen, Nan-kuei

    2014-01-01

    Purpose We report a series of techniques to reliably eliminate artifacts in interleaved echo-planar imaging (EPI) based diffusion weighted imaging (DWI). Methods First, we integrate the previously reported multiplexed sensitivity encoding (MUSE) algorithm with a new adaptive Homodyne partial-Fourier reconstruction algorithm, so that images reconstructed from interleaved partial-Fourier DWI data are free from artifacts even in the presence of either a) motion-induced k-space energy peak displacement, or b) susceptibility field gradient induced fast phase changes. Second, we generalize the previously reported single-band MUSE framework to multi-band MUSE, so that both through-plane and in-plane aliasing artifacts in multi-band multi-shot interleaved DWI data can be effectively eliminated. Results The new adaptive Homodyne-MUSE reconstruction algorithm reliably produces high-quality and high-resolution DWI, eliminating residual artifacts in images reconstructed with previously reported methods. Furthermore, the generalized MUSE algorithm is compatible with multi-band and high-throughput DWI. Conclusion The integration of the multi-band and adaptive Homodyne-MUSE algorithms significantly improves the spatial-resolution, image quality, and scan throughput of interleaved DWI. We expect that the reported reconstruction framework will play an important role in enabling high-resolution DWI for both neuroscience research and clinical uses. PMID:24925000

  18. Species adaptability, seed availability and prospects for improvement of eucalyptus in Minas Gerais

    Energy Technology Data Exchange (ETDEWEB)

    Ferrevia, M.; Balloni, E.A.; Pinto, J.E. Jr.; Jacob, W.S.

    1978-01-01

    As part of a continuing study into possible improvement of Eucalyptus spp. in plantations, data are presented from all existing trials and experimental plantings in Minas Gerais, Brazil. Growth, uniformity, form and fruiting are indicated.

  19. Data-driven adaptive selection of rule quality measures for improving rule induction and filtration algorithms

    Science.gov (United States)

    Sikora, Marek; Wróbel, Łukasz

    2013-08-01

    This paper presents a proposal of a rule induction algorithm selecting a rule quality measure adaptively. The quality measure plays the role of an optimization criterion of the generated rules. Nine quality measures applied by the algorithm are presented and discussed in the paper. It is shown experimentally that the proposed algorithm provides us with obtaining a classifier of the best quality. During experiments, three criteria of the classifier quality were considered: overall accuracy, balanced accuracy (average accuracy of decision classes), and complexity of the classifier (understood to mean the number of induced rules). The experiments were carried out on 34 data sets coming from the UCI machine learning repository. Moreover, a proposal of four-rule filtration algorithms is presented in the paper. Their task is to limit the number of rules in the classifier. In particular, filtration influence on the classifier quality is studied.

  20. Towards an improved wind speed scale and damage description adapted for Central Europe

    Science.gov (United States)

    Feuerstein, Bernold; Groenemeijer, Pieter; Dirksen, Erik; Hubrig, Martin; Holzer, Alois M.; Dotzek, Nikolai

    2011-06-01

    We propose an updated wind speed scale description adapted for Central Europe considering wind impact to buildings as well as to vegetation. The scale is motivated by the need of a broadly applicable, accurate and consistent tornado or downburst intensity rating system based on a standardised wind speed scale for the purpose of climatological homogeneity. The description comprises building and vegetation damage characteristics, which can be found in Central Europe - but similar in other parts of the world, occurring with the various classes of the Fujita- and T-scales. The scale description is supplemented by photographs of typical damage. For practical application, an ensemble-based use of a decision matrix for specific building structures and vegetation types is suggested.

  1. Identifying Ground-Robot Impedance to Improve Terrain Adaptability in Running Robots

    Directory of Open Access Journals (Sweden)

    Juan C. Arevalo

    2015-01-01

    Full Text Available To date, running robots are still outperformed by animals, but their dynamic behaviour can be described by the same model. This coincidence means that biomechanical studies can reveal much about the adaptability and energy efficiency of walking mechanisms. In particular, animals adjust their leg stiffness to negotiate terrains with different stiffnesses to keep the total leg-ground stiffness constant. In this work, we aim to provide one method to identify ground-robot impedance so that control can be applied to emulate the aforementioned animal behaviour. Experimental results of the method are presented, showing well-differentiated estimations on four different types of terrain. Additionally, an analysis of the convergence time is presented and compared with the contact time of humans while running, indicating that the method is suitable for use at high speeds.

  2. Cultural adaptation of an evidence-based nursing intervention to improve medication adherence among people living with HIV/AIDS (PLWHA) in China.

    Science.gov (United States)

    Williams, Ann B; Wang, Honghong; Burgess, Jane; Li, Xianhong; Danvers, Karina

    2013-04-01

    Adapting nursing interventions to suit the needs and culture of a new population (cultural adaptation) is an important early step in the process of implementation and dissemination. While the need for cultural adaptation is widely accepted, research-based strategies for doing so are not well articulated. Non-adherence to medications for chronic disease is a global problem and cultural adaptation of existing evidence-based interventions could be useful. This paper aims to describe the cultural adaptation of an evidence-based nursing intervention to improve medication adherence among people living with HIV/AIDS and to offer recommendations for adaptation of interventions across cultures and borders. SITE: The intervention, which demonstrated efficacy in a randomized controlled trial in North America, was adapted for the cultural and social context of Hunan Province, in south central China. The adaptation process was undertaken by intervention stakeholders including the original intervention study team, the proposed adaptation team, and members of a Community Advisory Board, including people living with HIV/AIDS, family members, and health care workers at the target clinical sites. The adaptation process was driven by quantitative and qualitative data describing the new population and context and was guided by principles for cultural adaptation drawn from prevention science research. The primary adaptation to the intervention was the inclusion of family members in intervention activities, in response to the cultural and social importance of the family in rural China. In a pilot test of the adapted intervention, self-reported medication adherence improved significantly in the group receiving the intervention compared to the control group (p=0.01). Recommendations for cultural adaptation of nursing interventions include (1) involve stakeholders from the beginning; (2) assess the population, need, and context; (3) evaluate the intervention to be adapted with attention to

  3. Adaptive spatial filtering improves speech reception in noise while preserving binaural cues.

    Science.gov (United States)

    Bissmeyer, Susan R S; Goldsworthy, Raymond L

    2017-09-01

    Hearing loss greatly reduces an individual's ability to comprehend speech in the presence of background noise. Over the past decades, numerous signal-processing algorithms have been developed to improve speech reception in these situations for cochlear implant and hearing aid users. One challenge is to reduce background noise while not introducing interaural distortion that would degrade binaural hearing. The present study evaluates a noise reduction algorithm, referred to as binaural Fennec, that was designed to improve speech reception in background noise while preserving binaural cues. Speech reception thresholds were measured for normal-hearing listeners in a simulated environment with target speech generated in front of the listener and background noise originating 90° to the right of the listener. Lateralization thresholds were also measured in the presence of background noise. These measures were conducted in anechoic and reverberant environments. Results indicate that the algorithm improved speech reception thresholds, even in highly reverberant environments. Results indicate that the algorithm also improved lateralization thresholds for the anechoic environment while not affecting lateralization thresholds for the reverberant environments. These results provide clear evidence that this algorithm can improve speech reception in background noise while preserving binaural cues used to lateralize sound.

  4. Cognitive replay of visuomotor learning at sleep onset: temporal dynamics and relationship to task performance.

    Science.gov (United States)

    Wamsley, Erin J; Perry, Karen; Djonlagic, Ina; Reaven, Laura Babkes; Stickgold, Robert

    2010-01-01

    Studies of neural activity in animals and humans suggest that experiences are "replayed" in cortical and hippocampal networks during NREM sleep. Here, we examine whether memory reactivation in sleeping humans might also be evident within reports of concomitant subjective experience (i.e., dreaming). Participants were trained on an engaging visuomotor learning task across a period of one or more days, and sleep onset mentation was collected at variable intervals using the "Nightcap" home-monitoring device. Verbal reports of sleep onset mentation were obtained either at the beginning of the night, or following 2 h of initial sleep. Data were collected in participants' home environments, via the Nightcap monitoring system, and at The Center for Sleep and Cognition, Beth Israel Deaconess Medical Center, Boston MA. 43 healthy, medication-free college students (16 males, age 18-25 years). N/A. The learning task exerted a powerful, direct effect on verbal reports of mentation during light NREM sleep (stages 1 and 2). On post-training nights, a full 30% of all verbal reports were related to the task. The nature of this cognitive "replay" effect was altered with increasing durations of sleep, becoming more abstracted from the original experience as time into sleep increased. These observations are interpreted in light of memory consolidation theory, and demonstrate that introspective reports can provide a valuable window on cognitive processing in the sleeping brain.

  5. Training wrist extensor function and detecting unwanted movement strategies in an EMG-controlled visuomotor task.

    Science.gov (United States)

    Lyu, Mingxing; Lambelet, Charles; Woolley, Daniel; Zhang, Xue; Chen, Weihai; Ding, Xilun; Gassert, Roger; Wenderoth, Nicole

    2017-07-01

    Stroke patients often suffer from severe upper limb paresis. Rehabilitation treatment typically targets motor impairments as early as possible, however, muscular contractions, particularly in the wrist and fingers, are often too weak to produce overt movements, making the initial phase of rehabilitation training difficult. Here we propose a new training tool whereby electromyographic (EMG) activity is measured in the wrist extensors and serves as a proxy of voluntary corticomotor drive. We used the Myo armband to develop a proportional EMG controller which allowed volunteers to perform a simple visuomotor task by modulating wrist extensor activity. In this preliminary study six healthy participants practiced the task for one session (144 trials), which resulted in a significant reduction of the average trial time required to move and hold a cursor in different target zones (p classifier to distinguish between the desired movement strategy and unwanted alternatives. Validation of the classifier indicated that accuracy for detecting rest, wrist extension and unwanted strategies was 92.5 + 6.9% (M + SD) across all participants. When performing the motor task the classification algorithm flagged 4.3 + 3.5% of the trials as 'unwanted strategies', even in healthy subjects. We also report initial feedback from a survey submitted to two chronic stroke patients to inquire about feasibility and acceptance of the general setup by patients.

  6. From self-observation to imitation: visuomotor association on a robotic hand.

    Science.gov (United States)

    Chaminade, Thierry; Oztop, Erhan; Cheng, Gordon; Kawato, Mitsuo

    2008-04-15

    Being at the crux of human cognition and behaviour, imitation has become the target of investigations ranging from experimental psychology and neurophysiology to computational sciences and robotics. It is often assumed that the imitation is innate, but it has more recently been argued, both theoretically and experimentally, that basic forms of imitation could emerge as a result of self-observation. Here, we tested this proposal on a realistic experimental platform, comprising an associative network linking a 16 degrees of freedom robotic hand and a simple visual system. We report that this minimal visuomotor association is sufficient to bootstrap basic imitation. Our results indicate that crucial features of human imitation, such as generalization to new actions, may emerge from a connectionist associative network. Therefore, we suggest that a behaviour as complex as imitation could be, at the neuronal level, founded on basic mechanisms of associative learning, a notion supported by a recent proposal on the developmental origin of mirror neurons. Our approach can be applied to the development of realistic cognitive architectures for humanoid robots as well as to shed new light on the cognitive processes at play in early human cognitive development.

  7. Control order and visuomotor strategy development for joystick-steered underground shuttle cars.

    Science.gov (United States)

    Cloete, Steven; Zupanc, Christine; Burgess-Limerick, Robin; Wallis, Guy

    2014-09-01

    In this simulator-based study, we aimed to quantify performance differences between joystick steering systems using first-order and second-order control, which are used in underground coal mining shuttle cars. In addition, we conducted an exploratory analysis of how users of the more difficult, second-order system changed their behavior over time. Evidence from the visuomotor control literature suggests that higher-order control devices are not intuitive, which could pose a significant risk to underground mine personnel, equipment, and infrastructure. Thirty-six naive participants were randomly assigned to first- and second-order conditions and completed three experimental trials comprising sequences of 90 degrees turns in a virtual underground mine environment, with velocity held constant at 9 km/h(-1). Performance measures were lateral deviation, steering angle variability, high-frequency steering content, joystick activity, and cumulative time in collision with the virtual mine wall. The second-order control group exhibited significantly poorer performance for all outcome measures. In addition, a series of correlation analyses revealed that changes in strategy were evident in the second-order group but not the first-order group. Results were consistent with previous literature indicating poorer performance with higher-order control devices and caution against the adoption of the second-order joystick system for underground shuttle cars. Low-cost, portable simulation platforms may provide an effective basis for operator training and recruitment.

  8. Contributions of the hippocampus and entorhinal cortex to rapid visuomotor learning in rhesus monkeys.

    Science.gov (United States)

    Yang, Tianming; Bavley, Rachel L; Fomalont, Kevin; Blomstrom, Kevin J; Mitz, Andrew R; Turchi, Janita; Rudebeck, Peter H; Murray, Elisabeth A

    2014-09-01

    The hippocampus and adjacent structures in the medial temporal lobe are essential for establishing new associative memories. Despite this knowledge, it is not known whether the hippocampus proper is essential for establishing such memories, nor is it known whether adjacent regions like the entorhinal cortex might contribute. To test the contributions of these regions to the formation of new associative memories, we trained rhesus monkeys to rapidly acquire arbitrary visuomotor associations, i.e., associations between visual stimuli and spatially directed actions. We then assessed the effects of reversible inactivations of either the hippocampus (Experiment 1) or entorhinal cortex (Experiment 2) on the within-session rate of learning. For comparison, we also evaluated the effects of the inactivations on performance of problems of the same type that had been well learned prior to any inactivations. We found that inactivation of the entorhinal cortex but not hippocampus produced impairments in acquiring novel arbitrary associations. The impairment did not extend to the familiar, previously established associations. These data indicate that the entorhinal cortex is causally involved in establishing new associations, as opposed to retrieving previously learned associations. Published 2014. This article is a U.S. Government work and is in the public domain in the USA. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  9. An adaptation method to improve secret key rates of time-frequency QKD in atmospheric turbulence channels

    Science.gov (United States)

    Sun, Xiaole; Djordjevic, Ivan B.; Neifeld, Mark A.

    2016-03-01

    Free-space optical (FSO) channels can be characterized by random power fluctuations due to atmospheric turbulence, which is known as scintillation. Weak coherent source based FSO quantum key distribution (QKD) systems suffer from the scintillation effect because during the deep channel fading the expected detection rate drops, which then gives an eavesdropper opportunity to get additional information about protocol by performing photon number splitting (PNS) attack and blocking single-photon pulses without changing QBER. To overcome this problem, in this paper, we study a large-alphabet QKD protocol, which is achieved by using pulse-position modulation (PPM)-like approach that utilizes the time-frequency uncertainty relation of the weak coherent photon state, called here TF-PPM-QKD protocol. We first complete finite size analysis for TF-PPM-QKD protocol to give practical bounds against non-negligible statistical fluctuation due to finite resources in practical implementations. The impact of scintillation under strong atmospheric turbulence regime is studied then. To overcome the secure key rate performance degradation of TF-PPM-QKD caused by scintillation, we propose an adaptation method for compensating the scintillation impact. By changing source intensity according to the channel state information (CSI), obtained by classical channel, the adaptation method improves the performance of QKD system with respect to the secret key rate. The CSI of a time-varying channel can be predicted using stochastic models, such as autoregressive (AR) models. Based on the channel state predictions, we change the source intensity to the optimal value to achieve a higher secret key rate. We demonstrate that the improvement of the adaptation method is dependent on the prediction accuracy.

  10. Improvements to the ShipIR/NTCS adaptive track gate algorithm and 3D flare particle model

    Science.gov (United States)

    Ramaswamy, Srinivasan; Vaitekunas, David A.; Gunter, Willem H.; February, Faith J.

    2017-05-01

    A key component in any image-based tracking system is the adaptive tracking algorithm used to segment the image into potential targets, rank-and-select the best candidate target, and gate the selected target to further improve tracker performance. Similarly, a key component in any soft-kill response to an incoming guided missile is the flare/chaff decoy used to distract or seduce the seeker homing system away from the naval platform. This paper describes the recent improvements to the naval threat countermeasure simulator (NTCS) of the NATO-standard ship signature model (ShipIR). Efforts to analyse and match the 3D flare particle model against actual IR measurements of the Chemring TALOS IR round resulted in further refinement of the 3D flare particle distribution. The changes in the flare model characteristics were significant enough to require an overhaul to the adaptive track gate (ATG) algorithm in the way it detects the presence of flare decoys and reacquires the target after flare separation. A series of test scenarios are used to demonstrate the impact of the new flare and ATG on IR tactics simulation.

  11. Adaptive neuro-fuzzy inference system to improve the power quality of a split shaft microturbine power generation system

    Science.gov (United States)

    Oğuz, Yüksel; Üstün, Seydi Vakkas; Yabanova, İsmail; Yumurtaci, Mehmet; Güney, İrfan

    2012-01-01

    This article presents design of adaptive neuro-fuzzy inference system (ANFIS) for the turbine speed control for purpose of improving the power quality of the power production system of a split shaft microturbine. To improve the operation performance of the microturbine power generation system (MTPGS) and to obtain the electrical output magnitudes in desired quality and value (terminal voltage, operation frequency, power drawn by consumer and production power), a controller depended on adaptive neuro-fuzzy inference system was designed. The MTPGS consists of the microturbine speed controller, a split shaft microturbine, cylindrical pole synchronous generator, excitation circuit and voltage regulator. Modeling of dynamic behavior of synchronous generator driver with a turbine and split shaft turbine was realized by using the Matlab/Simulink and SimPowerSystems in it. It is observed from the simulation results that with the microturbine speed control made with ANFIS, when the MTPGS is operated under various loading situations, the terminal voltage and frequency values of the system can be settled in desired operation values in a very short time without significant oscillation and electrical production power in desired quality can be obtained.

  12. Improving productivity software through the adaptation of an agile development framework

    Directory of Open Access Journals (Sweden)

    Ángel Fiallos Ordoñez

    2015-06-01

    Full Text Available (Received: 2015/02/20 - Accepted: 2015/06/17The current research suggests that using of agile methodologies in conjunction with open source software tools can improve productivity, reduce costs and optimize resources in the process of software development, and helps improve user satisfaction due to implementation of excellent quality software. The following analysis shows the most important variables for the successful implementation of IT development projects and their relation with the use of traditional and agile software development methodologies.

  13. Gait adaptability training improves obstacle avoidance and dynamic stability in patients with cerebellar degeneration

    NARCIS (Netherlands)

    Fonteyn, E.M.R.; Heeren, A.; Engels, J.J.; Boer, J.J. den; Warrenburg, B.P.C. van de; Weerdesteyn, V.G.M.

    2014-01-01

    Balance and gait problems in patients with cerebellar degeneration lead to reduced mobility, loss of independence, and frequent falls. It is currently unclear, however, whether balance and gait capacities can be improved by training in this group of patients. Therefore, the aim of this study was to

  14. Adapting to climate change in Malawi by improving soils and nutrition

    International Development Research Centre (IDRC) Digital Library (Canada)

    2016-04-28

    Apr 28, 2016 ... ... ecohealth approach to research: Helping communities control leishmaniasis in rural Tunisia · Involving urban communities in controlling dengue fever in Latin America · Preventing Chagas in Central America through simple home improvements · Reducing liver fluke transmission in northeastern Thailand ...

  15. Improving peri-prosthetic bone adaptation around cementless hip stems: A clinical and finite element study

    NARCIS (Netherlands)

    Broeke, R.H. Ten; Tarala, M.; Arts, J.J.C.; Janssen, D.W.; Verdonschot, N.J.J.; Geesink, R.G.T.

    2014-01-01

    This study assessed whether the Symax implant, a modification of the Omnifit((R)) stem (in terms of shape, proximal coating and distal surface treatment), would yield improved bone remodelling in a clinical DEXA study, and if these results could be predicted in a finite element (FE) simulation

  16. Improving peri-prosthetic bone adaptation around cementless hip stems: A clinical and finite element study

    NARCIS (Netherlands)

    ten Broeke, R.H.M.; Tarala, M.; Arts, J.J.; Janssen, D.W.; Verdonschot, Nicolaas Jacobus Joseph; Geesink, R.G.T.

    2014-01-01

    This study assessed whether the Symax™ implant, a modification of the Omnifit® stem (in terms of shape, proximal coating and distal surface treatment), would yield improved bone remodelling in a clinical DEXA study, and if these results could be predicted in a finite element (FE) simulation study.

  17. Investigation of instabilities affecting detonations: Improving the resolution using block-structured adaptive mesh refinement

    Science.gov (United States)

    Ravindran, Prashaanth

    The unstable nature of detonation waves is a result of the critical relationship between the hydrodynamic shock and the chemical reactions sustaining the shock. A perturbative analysis of the critical point is quite challenging due to the multiple spatio-temporal scales involved along with the non-linear nature of the shock-reaction mechanism. The author's research attempts to provide detailed resolution of the instabilities at the shock front. Another key aspect of the present research is to develop an understanding of the causality between the non-linear dynamics of the front and the eventual breakdown of the sub-structures. An accurate numerical simulation of detonation waves requires a very efficient solution of the Euler equations in conservation form with detailed, non-equilibrium chemistry. The difference in the flow and reaction length scales results in very stiff source terms, requiring the problem to be solved with adaptive mesh refinement. For this purpose, Berger-Colella's block-structured adaptive mesh refinement (AMR) strategy has been developed and applied to time-explicit finite volume methods. The block-structured technique uses a hierarchy of parent-child sub-grids, integrated recursively over time. One novel approach to partition the problem within a large supercomputer was the use of modified Peano-Hilbert space filling curves. The AMR framework was merged with CLAWPACK, a package providing finite volume numerical methods tailored for wave-propagation problems. The stiffness problem is bypassed by using a 1st order Godunov or a 2nd order Strang splitting technique, where the flow variables and source terms are integrated independently. A linearly explicit fourth-order Runge-Kutta integrator is used for the flow, and an ODE solver was used to overcome the numerical stiffness. Second-order spatial resolution is obtained by using a second-order Roe-HLL scheme with the inclusion of numerical viscosity to stabilize the solution near the discontinuity

  18. Context-dependent adaptation improves robustness of myoelectric control for upper-limb prostheses

    Science.gov (United States)

    Patel, Gauravkumar K.; Hahne, Janne M.; Castellini, Claudio; Farina, Dario; Dosen, Strahinja

    2017-10-01

    Objective. Dexterous upper-limb prostheses are available today to restore grasping, but an effective and reliable feed-forward control is still missing. The aim of this work was to improve the robustness and reliability of myoelectric control by using context information from sensors embedded within the prosthesis. Approach. We developed a context-driven myoelectric control scheme (cxMYO) that incorporates the inference of context information from proprioception (inertial measurement unit) and exteroception (force and grip aperture) sensors to modulate the outputs of myoelectric control. Further, a realistic evaluation of the cxMYO was performed online in able-bodied subjects using three functional tasks, during which the cxMYO was compared to a purely machine-learning-based myoelectric control (MYO). Main results. The results demonstrated that utilizing context information decreased the number of unwanted commands, improving the performance (success rate and dropped objects) in all three functional tasks. Specifically, the median number of objects dropped per round with cxMYO was zero in all three tasks and a significant increase in the number of successful transfers was seen in two out of three functional tasks. Additionally, the subjects reported better user experience. Significance. This is the first online evaluation of a method integrating information from multiple on-board prosthesis sensors to modulate the output of a machine-learning-based myoelectric controller. The proposed scheme is general and presents a simple, non-invasive and cost-effective approach for improving the robustness of myoelectric control.

  19. ADAPTED SWIMMING TRAINING FOCUSED ON IMPROVEMENT OF PSYCHOPHYSICAL STATUS OD ELDERLY PEOPLE

    Directory of Open Access Journals (Sweden)

    Dragan Krivokapić

    2015-05-01

    Full Text Available In developed countries chronological age from 65 is often mentioned as age limit when elderly age begins, and which is featured by significant changes in organic functions as well as social relations. Thanks to qualitative medical care and contemporary ways of treatment, an average lifetime has been prolonged. Therefore, according to some data in developed countries of Western Europe, each fourth inhabitant is older than 65. However, there psychophysical abilities are very weak, and health is bad, which directly influences reduction in life quality. Adapted physical activities in water adjusted to abilities and health state of elderly people give a series of advantages in comparison to exercises that can be done outside water. For that reason, in those conditions effect of gravity is reduced, so PTO-skeletal system suffers a lot less burden than at practicing on dry. Taking into account that postural system with elderly people is often damaged, great advantage at exercising in water enables horizontal position that a person takes. That beneficially influences first of all the spinal cord, which is in horizontal position disburdened from gravity influence which beneficially affects spinal disease. Results of numerous researches indicate that swimming harmonically burdens organism so that almost all musculature of upper and lower extremities, belly and pelvis area. Swimming accelerates blood circulation, heart gets more blood which directly affects increase in minute volume. Eventually it all brings to fortification of heart muscle and more permanent increase of its functional abilities. Possibility of precise dosing of burden in swimming enables excellent way of therapy with elderly people and those with damaged heart. Besides, activated musculature enables fast relaxation of organism and restore of all vital cardio respiratory functions to the level of standard work ability of a man.

  20. Incorporating Deeply Uncertain Factors into the Many Objective Search Process: Improving Adaptation to Environmental Change

    Science.gov (United States)

    Kasprzyk, J. R.; Watson, A. A.

    2014-12-01

    Deep uncertainty refers to situations in which decision makers or stakeholders do not know, or cannot fully agree upon, the full suite of risk factors within a planning problem. This phenomenon is especially important when considering scenarios of future environmental change, since there exist multiple trajectories of environmental forcings (e.g., streamflow timing and magnitude) and socioeconomic factors (e.g., population growth). This presentation first briefly reviews robust optimization and scenario approaches that have been proposed to plan for systems under deep uncertainty. One recently introduced framework is Many Objective Robust Decision Making (MORDM). MORDM combines two techniques: evolutionary algorithm search is used to generate planning alternatives, and robust decision making methods are used to sample performance over a large range of plausible factors and, subsequently, choose a robust solution. Within MORDM, Pareto approximate tradeoff sets of solutions are used to balance objectives and examine alternatives. However, MORDM does not currently incorporate the deeply uncertain scenario information into the search process itself. In this presentation, we suggest several avenues for doing so, that are focused on modifying the suite of uncertain data that is selected within the search process. Visualizations that compare tradeoff sets across different sets of assumptions can be used to guide decision makers' learning and, ultimately, their selection of several candidate solutions for further planning. For example, the baseline assumptions about probability distributions can be compared to optimization results under severe events to determine adaptive management strategies. A case study of water planning in the Lower Rio Grande Valley (LRGV) in Texas is used to demonstrate the approach. Our LRGV results compare baseline optimization with new solution sets that examine optimal management strategies under scenarios characterized by lower than average

  1. Improving Inpatient Surveys: Web-Based Computer Adaptive Testing Accessed via Mobile Phone QR Codes.

    Science.gov (United States)

    Chien, Tsair-Wei; Lin, Weir-Sen

    2016-03-02

    The National Health Service (NHS) 70-item inpatient questionnaire surveys inpatients on their perceptions of their hospitalization experience. However, it imposes more burden on the patient than other similar surveys. The literature shows that computerized adaptive testing (CAT) based on item response theory can help shorten the item length of a questionnaire without compromising its precision. Our aim was to investigate whether CAT can be (1) efficient with item reduction and (2) used with quick response (QR) codes scanned by mobile phones. After downloading the 2008 inpatient survey data from the Picker Institute Europe website and analyzing the difficulties of this 70-item questionnaire, we used an author-made Excel program using the Rasch partial credit model to simulate 1000 patients' true scores followed by a standard normal distribution. The CAT was compared to two other scenarios of answering all items (AAI) and the randomized selection method (RSM), as we investigated item length (efficiency) and measurement accuracy. The author-made Web-based CAT program for gathering patient feedback was effectively accessed from mobile phones by scanning the QR code. We found that the CAT can be more efficient for patients answering questions (ie, fewer items to respond to) than either AAI or RSM without compromising its measurement accuracy. A Web-based CAT inpatient survey accessed by scanning a QR code on a mobile phone was viable for gathering inpatient satisfaction responses. With advances in technology, patients can now be offered alternatives for providing feedback about hospitalization satisfaction. This Web-based CAT is a possible option in health care settings for reducing the number of survey items, as well as offering an innovative QR code access.

  2. Proposing an adaptive mutation to improve XCSF performance to classify ADHD and BMD patients

    Science.gov (United States)

    Sadatnezhad, Khadijeh; Boostani, Reza; Ghanizadeh, Ahmad

    2010-12-01

    There is extensive overlap of clinical symptoms observed among children with bipolar mood disorder (BMD) and those with attention deficit hyperactivity disorder (ADHD). Thus, diagnosis according to clinical symptoms cannot be very accurate. It is therefore desirable to develop quantitative criteria for automatic discrimination between these disorders. This study is aimed at designing an efficient decision maker to accurately classify ADHD and BMD patients by analyzing their electroencephalogram (EEG) signals. In this study, 22 channels of EEGs have been recorded from 21 subjects with ADHD and 22 individuals with BMD. Several informative features, such as fractal dimension, band power and autoregressive coefficients, were extracted from the recorded signals. Considering the multimodal overlapping distribution of the obtained features, linear discriminant analysis (LDA) was used to reduce the input dimension in a more separable space to make it more appropriate for the proposed classifier. A piecewise linear classifier based on the extended classifier system for function approximation (XCSF) was modified by developing an adaptive mutation rate, which was proportional to the genotypic content of best individuals and their fitness in each generation. The proposed operator controlled the trade-off between exploration and exploitation while maintaining the diversity in the classifier's population to avoid premature convergence. To assess the effectiveness of the proposed scheme, the extracted features were applied to support vector machine, LDA, nearest neighbor and XCSF classifiers. To evaluate the method, a noisy environment was simulated with different noise amplitudes. It is shown that the results of the proposed technique are more robust as compared to conventional classifiers. Statistical tests demonstrate that the proposed classifier is a promising method for discriminating between ADHD and BMD patients.

  3. Adapted Tango Improves Mobility, Motor-Cognitive Function, and Gait but Not Cognition in Older Adults in Independent Living.

    Science.gov (United States)

    Hackney, Madeleine E; Byers, Colleen; Butler, Gail; Sweeney, Morgan; Rossbach, Lauren; Bozzorg, Aaron

    2015-10-01

    To determine the efficacy of adapted tango for improving mobility, motor-cognitive function, and gait; to determine whether former dance experience was associated with improvements; and to evaluate participant satisfaction, changes in depression, and quality of life. Quasi-experimental, two-group, repeated-measures preintervention, postintervention, and 3-month postintervention study. Diverse senior independent living communities in an urban metropolitan area. Individuals aged 59 to 95 (73% aged 80 and older; 31% nonwhite, 72% female) (N = 74). Participants were assigned to 20 sessions of 90-minute tango (n = 62) or health education (n = 12) classes over 12 weeks. Mobility, motor-cognitive function, gait, cognition, and psychosocial function were evaluated before, immediately after, and 3 months after the intervention. Two (groups) by two (before and after) repeated-measures analyses of variance with post hoc comparisons were used to evaluate differences in primary analyses. Secondary analyses from immediately after to 3 months after were used to examine the data for retention of any gains. Forty-four tango and 10 education participants completed 20 sessions. Significant group by time interactions revealed that tango improved mobility (P = .006), backward and fast gait speeds (P tango may improve mobility, gait and motor-cognitive function more than health education classes in older adults. Further research is necessary to confirm these findings. © 2015, Copyright the Authors Journal compilation © 2015, The American Geriatrics Society.

  4. An improved adaptive interpolation clock recovery loop based on phase splitting algorithm for coherent optical communication system

    Science.gov (United States)

    Liu, Xuan; Liu, Bo; Zhang, Li-jia; Xin, Xiang-jun; Zhang, Qi; Wang, Yong-jun; Tian, Qing-hua; Tian, Feng; Mao, Ya-ya

    2018-01-01

    Traditional clock recovery scheme achieves timing adjustment by digital interpolation, thus recovering the sampling sequence. Based on this, an improved clock recovery architecture joint channel equalization for coherent optical communication system is presented in this paper. The loop is different from the traditional clock recovery. In order to reduce the interpolation error caused by the distortion in the frequency domain of the interpolator and to suppress the spectral mirroring generated by the sampling rate change, the proposed algorithm joint equalization, improves the original interpolator in the loop, along with adaptive filtering, and makes error compensation for the original signals according to the balanced pre-filtering signals. Then the signals are adaptive interpolated through the feedback loop. Furthermore, the phase splitting timing recovery algorithm is adopted in this paper. The time error is calculated according to the improved algorithm when there is no transition between the adjacent symbols, making calculated timing error more accurate. Meanwhile, Carrier coarse synchronization module is placed before the beginning of timing recovery to eliminate the larger frequency offset interference, which effectively adjust the sampling clock phase. In this paper, the simulation results show that the timing error is greatly reduced after the loop is changed. Based on the phase splitting algorithm, the BER and MSE are better than those in the unvaried architecture. In the fiber channel, using MQAM modulation format, after 100 km-transmission of single-mode fiber, especially when ROF(roll-off factor) values tends to 0, the algorithm shows a better clock performance under different ROFs. When SNR values are less than 8, the BER could achieve 10-2 to 10-1 magnitude. Furthermore, the proposed timing recovery is more suitable for the situation with low SNR values.

  5. Simultaneous adaptive control of dual deformable mirrors for full-field beam shaping with the improved stochastic parallel gradient descent algorithm.

    Science.gov (United States)

    Ma, Haotong; Liu, Zejin; Xu, Xiaojun; Chen, Jinbao

    2013-02-01

    We propose and demonstrate the simultaneous adaptive control of a dual deformable mirror system for full-field beam shaping based on an improved stochastic parallel gradient descent (SPGD) algorithm and dual-phase-only liquid crystal spatial light modulators (LC-SLMs). One LC-SLM adaptively redistributes the intensity of the input beam and the other adaptively compensates the wavefront of the output beam. However, the intensity redistribution and wavefront compensation closed loops run simultaneously. In addition, the intensity redistribution and wavefront compensation closed loops adopt their respective metric functions independently. Experimental results show that the improved SPGD algorithm can not only be used for controlling dual deformable mirror configuration to adaptively generate near diffraction-limited flattop beams with desired intensity distributions, but also can greatly improve the control bandwidth.

  6. Cross-cultural adaptation into portuguese of the Dynamic Occupational Therapy Cognitive Assessment for Children (DOTCA-Ch

    Directory of Open Access Journals (Sweden)

    Lúcia da Rocha Uchôa-Figueiredo

    2017-06-01

    Full Text Available Introduction: The DOTCA-Ch Battery (Dynamic Occupational Therapy Cognitive Assessment for Children is a specific assessment tool for occupational therapists (O.T.. The battery evaluates the cognitive performance of 6- to 12-year-old children, from 22 dynamic subtests distributed in five cognitive areas: Orientation, Spatial Perception, Praxis, Visuomotor Construction and Thinking Operations. Objective: To demonstrate how the cross-cultural adaptation process of the DOTCA-Ch Battery into Portuguese took place. Method: The DOTCA-Ch Battery was translated and adapted according to a rigorous methodology that proposes the translation, back-translation, and Conceptual, Cultural, Idiomatic and Semantic equivalence evaluation by a committee of experts and through a following pre-test. Results: The DOTCA-Ch Battery was translated and adapted for Brazilian Portuguese and back-translated to the original language. After that, a committee of five experts evaluated 375 items in order to assess the equivalences, taking into consideration the target population and the cultural context of Brazil. In the pre-test phase, this version was applied to 09 healthy children of the city of Santos. Conclusion: The DOTCA-Ch battery is feasible to be used with healthy children. However, some adjustments related to the time of application are necessary in the case of this specific population group. It was observed that children benefit from the use of mediation, as this considerably improved their performance during the execution of tasks.

  7. Application of an adaptive acquisition regularization parameter based on an improved GCV criterion in pre-stack AVO inversion

    Science.gov (United States)

    Huang, Guangtan; Chen, Xiaohong; Li, Jingye; Luo, Cong; Wang, Benfeng

    2017-02-01

    In exploration geophysics, AVO inversion is undoubtedly the most common inverse problem which is ill-posed and must be regularized. Once regularization is used, the selection of the regularization parameter will become an important problem to solve. In practice, the proper regularization parameter value is usually data dependent and determined empirically. For one work area, inversion engineers often give a fixed parameter. In such a case, the results of AVO inversion will be accompanied by strong artificial subjective factors. Besides, it is difficult to guarantee that the fixed parameter could be applied to each trace of the seismic data. In this paper, we first emphasize the importance of the regularization parameter selection for the inverse problems. Then, based on a traditional GCV function, we propose an adaptive acquisition regularization parameter method which can be used in regularization for arbitrary norm conditions, and derive the theoretical formula of the adaptive computation of the regularization parameter. Applying this method to the AVO inversion of synthetic data and field data, we have found that the improved GCV method has better accuracy and robustness than the traditional method.

  8. Improvements in intelligibility of noisy reverberant speech using a binaural subband adaptive noise-cancellation processing scheme

    Science.gov (United States)

    Shields, Paul W.; Campbell, Douglas R.

    2001-12-01

    This article reports on the performance of an adaptive subband noise cancellation scheme, which performs binaural preprocessing of speech signals for a hearing-aid application. The multi-microphone subband adaptive (MMSBA) signal processing scheme uses the least mean squares (LMS) algorithm in frequency-limited subbands. The use of subbands enables a diverse processing mechanism to be employed, splitting the two-channel wide-band signal into smaller frequency-limited subbands, which can be processed according to their individual signal characteristics. The frequency delimiting used a linear- or cochlear-spaced subband distribution. The effect of the processing scheme on speech intelligibility was assessed in a trial involving 15 hearing-impaired volunteers with moderate sensorineural hearing loss. The acoustic material consisted of speech and speech-shaped noise signals, generated using simulated and real-room acoustic environments, at signal-to-noise ratios (SNRs) in the range -6 to +3 dB. The results show that the MMSBA scheme delivered average speech intelligibility improvements of 11.5%, with a maximum of 37.25%, in noisy reverberant conditions. There was no significant reduction in mean speech intelligibility due to processing, in any of the test conditions.

  9. Assessing the effectiveness and cost effectiveness of adaptive e-Learning to improve dietary behaviour: protocol for a systematic review

    Directory of Open Access Journals (Sweden)

    Michie Susan

    2010-04-01

    Full Text Available Abstract Background The composition of habitual diets is associated with adverse or protective effects on aspects of health. Consequently, UK public health policy strongly advocates dietary change for the improvement of population health and emphasises the importance of individual empowerment to improve health. A new and evolving area in the promotion of dietary behavioural change is e-Learning, the use of interactive electronic media to facilitate teaching and learning on a range of issues, including diet and health. The aims of this systematic review are to determine the effectiveness and cost-effectiveness of adaptive e-Learning for improving dietary behaviours. Methods/Design The research will consist of a systematic review and a cost-effectiveness analysis. Studies will be considered for the review if they are randomised controlled trials, involving participants aged 13 or over, which evaluate the effectiveness or efficacy of interactive software programmes for improving dietary behaviour. Primary outcome measures will be those related to dietary behaviours, including estimated intakes of energy, nutrients and dietary fibre, or the estimated number of servings per day of foods or food groups. Secondary outcome measures will be objective clinical measures that are likely to respond to changes in dietary behaviours, such as anthropometry or blood biochemistry. Knowledge, self-efficacy, intention and emotion will be examined as mediators of dietary behaviour change in order to explore potential mechanisms of action. Databases will be searched using a comprehensive four-part search strategy, and the results exported to a bibliographic database. Two review authors will independently screen results to identify potentially eligible studies, and will independently extract data from included studies, with any discrepancies at each stage settled by a third author. Standardised forms and criteria will be used. A descriptive analysis of included

  10. Assessing the effectiveness and cost effectiveness of adaptive e-Learning to improve dietary behaviour: protocol for a systematic review.

    Science.gov (United States)

    Edwards, Phil; Felix, Lambert; Harris, Jody; Ferguson, Elaine; Free, Caroline; Landon, Jane; Lock, Karen; Michie, Susan; Miners, Alec; Murray, Elizabeth

    2010-04-21

    The composition of habitual diets is associated with adverse or protective effects on aspects of health. Consequently, UK public health policy strongly advocates dietary change for the improvement of population health and emphasises the importance of individual empowerment to improve health. A new and evolving area in the promotion of dietary behavioural change is e-Learning, the use of interactive electronic media to facilitate teaching and learning on a range of issues, including diet and health. The aims of this systematic review are to determine the effectiveness and cost-effectiveness of adaptive e-Learning for improving dietary behaviours. The research will consist of a systematic review and a cost-effectiveness analysis. Studies will be considered for the review if they are randomised controlled trials, involving participants aged 13 or over, which evaluate the effectiveness or efficacy of interactive software programmes for improving dietary behaviour. Primary outcome measures will be those related to dietary behaviours, including estimated intakes of energy, nutrients and dietary fibre, or the estimated number of servings per day of foods or food groups. Secondary outcome measures will be objective clinical measures that are likely to respond to changes in dietary behaviours, such as anthropometry or blood biochemistry. Knowledge, self-efficacy, intention and emotion will be examined as mediators of dietary behaviour change in order to explore potential mechanisms of action. Databases will be searched using a comprehensive four-part search strategy, and the results exported to a bibliographic database. Two review authors will independently screen results to identify potentially eligible studies, and will independently extract data from included studies, with any discrepancies at each stage settled by a third author. Standardised forms and criteria will be used.A descriptive analysis of included studies will describe study design, participants, the

  11. Improving Naive Bayes with Online Feature Selection for Quick Adaptation to Evolving Feature Usefulness

    Energy Technology Data Exchange (ETDEWEB)

    Pon, R K; Cardenas, A F; Buttler, D J

    2007-09-19

    The definition of what makes an article interesting varies from user to user and continually evolves even for a single user. As a result, for news recommendation systems, useless document features can not be determined a priori and all features are usually considered for interestingness classification. Consequently, the presence of currently useless features degrades classification performance [1], particularly over the initial set of news articles being classified. The initial set of document is critical for a user when considering which particular news recommendation system to adopt. To address these problems, we introduce an improved version of the naive Bayes classifier with online feature selection. We use correlation to determine the utility of each feature and take advantage of the conditional independence assumption used by naive Bayes for online feature selection and classification. The augmented naive Bayes classifier performs 28% better than the traditional naive Bayes classifier in recommending news articles from the Yahoo! RSS feeds.

  12. Exploiting the Interplay between Innate and Adaptive Immunity to Improve Immunotherapeutic Strategies for Epstein-Barr-Virus-Driven Disorders

    Directory of Open Access Journals (Sweden)

    Debora Martorelli

    2012-01-01

    Full Text Available The recent demonstration that immunotherapeutic approaches may be clinically effective for cancer patients has renewed the interest for this strategy of intervention. In particular, clinical trials using adoptive T-cell therapies disclosed encouraging results, particularly in the context of Epstein-Barr-virus- (EBV- related tumors. Nevertheless, the rate of complete clinical responses is still limited, thus stimulating the development of more effective therapeutic protocols. Considering the relevance of innate immunity in controlling both infections and cancers, innovative immunotherapeutic approaches should take into account also this compartment to improve clinical efficacy. Evidence accumulated so far indicates that innate immunity effectors, particularly NK cells, can be exploited with therapeutic purposes and new targets have been recently identified. We herein review the complex interactions between EBV and innate immunity and summarize the therapeutic strategies involving both adaptive and innate immune system, in the light of a fruitful integration between these immunotherapeutic modalities for a better control of EBV-driven tumors.

  13. [Adaptability of Helianthus annuus seedlings to crude oil pollution in soil and its improvement measures under salinization stress].

    Science.gov (United States)

    Zhang, Jing-lei; Ci, Hua-cong; He, Xing-dong; Liang, Yu-ting; Zhao, Xuan; Sun, Hui-ting; Xie, Hong-tao

    2015-11-01

    To explore the adaptability of plant under salt stress to crude oil pollution of soil and improvement measures, a pot experiment of Helianthus annuus seedlings was conducted using orthogonal experiment method with crude oil-sodium chloride-desulfurization gypsum and cinder-zeolite-desulfurization gypsum-sawdust. The results showed that, with the increase of soil crude oil concentration, the relative growth rate (RGR) of plant height, RGR of aboveground biomass and root N: P ratios of H. annuus seedlings decreased significantly, while the activity of SOD and CAT increased at first and then decreased significantly. The RGR of plant height and aboveground biomass significantly increased (P pollution of soil could decrease the relative growth rate of H. annuus seedling, and sawdust could reduce the influence of crude oil pollution on plant growth under salt stress.

  14. Adaptive Reactive Power Control of PV Power Plants for Improved Power Transfer Capability under Ultra-Weak Grid Conditions

    DEFF Research Database (Denmark)

    Yang, Dongsheng; Wang, Xiongfei; Liu, Fangcheng

    2018-01-01

    the ultra-weak grid is significantly improved with the low PF operation. An adaptive reactive power droop control is next proposed to effectively distribute the reactive power demands to the individual inverters, and meanwhile maximize the power transfer capacity of the PV power plant. Simulation results......This paper analyzes the power transfer limitation of the PV power plant under the ultra-weak grid condition, i.e., when the Short-Circuit Ratio (SCR) is close to 1. It explicitly identifies that a minimum SCR of 2 is required for the PV power plant to deliver the rated active power when operating...... of a 200 MW PV power plant demonstrate that the proposed method can ensure the rated power transfer of PV power plant with the SCR of 1.25, provided that the PV inverters are operated with the minimal PF=0.9....

  15. Prism adaptation in Parkinson disease: comparing reaching to walking and freezers to non-freezers.

    Science.gov (United States)

    Nemanich, Samuel T; Earhart, Gammon M

    2015-08-01

    Visuomotor adaptation to gaze-shifting prism glasses requires recalibration of the relationship between sensory input and motor output. Healthy individuals flexibly adapt movement patterns to many external perturbations; however, individuals with cerebellar damage do not adapt movements to the same extent. People with Parkinson disease (PD) adapt normally, but exhibit reduced after-effects, which are negative movement errors following the removal of the prism glasses and are indicative of true spatial realignment. Walking is particularly affected in PD, and many individuals experience freezing of gait (FOG), an episodic interruption in walking, that is thought to have a distinct pathophysiology. Here, we examined how individuals with PD with (PD + FOG) and without (PD - FOG) FOG, along with healthy older adults, adapted both reaching and walking patterns to prism glasses. Participants completed a visually guided reaching and walking task with and without rightward-shifting prism glasses. All groups adapted at similar rates during reaching and during walking. However, overall walking adaptation rates were slower compared to reaching rates. The PD - FOG group showed smaller after-effects, particularly during walking, compared to PD + FOG, independent of adaptation magnitude. While FOG did not appear to affect characteristics of prism adaptation, these results support the idea that the distinct neural processes governing visuomotor adaptation and storage are differentially affected by basal ganglia dysfunction in PD.

  16. Image quality improvements using adaptive statistical iterative reconstruction for evaluating chronic myocardial infarction using iodine density images with spectral CT.

    Science.gov (United States)

    Kishimoto, Junichi; Ohta, Yasutoshi; Kitao, Shinichiro; Watanabe, Tomomi; Ogawa, Toshihide

    2017-10-19

    Single-source dual-energy CT (ssDECT) allows the reconstruction of iodine density images (IDIs) from projection based computing. We hypothesized that adding adaptive statistical iterative reconstruction (ASiR) could improve image quality. The aim of our study was to evaluate the effect and determine the optimal blend percentages of ASiR for IDI of myocardial late iodine enhancement (LIE) in the evaluation of chronic myocardial infarction using ssDECT. A total of 28 patients underwent cardiac LIE using a ssDECT scanner. IDIs between 0 and 100% of ASiR contributions in 10% increments were reconstructed. The signal-to-noise ratio (SNR) of remote myocardia and the contrast-to-noise ratio (CNR) of infarcted myocardia were measured. Transmural extent of infarction was graded using a 5-point scale. The SNR, CNR, and transmural extent were assessed for each ASiR contribution ratio. The transmural extents were compared with MRI as a reference standard. Compared to 0% ASiR, the use of 20-100% ASiR resulted in a reduction of image noise (p ASiR images, reconstruction with 100% ASiR image showed the highest improvement in SNR (229%; p ASiR above 80% showed the highest ratio (73.7%) of accurate transmural extent classification. In conclusion, ASiR intensity of 80-100% in IDIs can improve image quality without changes in signal and maximizes the accuracy of transmural extent in infarcted myocardium.

  17. Electroencephalographic (eeg coherence between visual and motor areas of the left and the right brain hemisphere while performing visuomotor task with the right and the left hand

    Directory of Open Access Journals (Sweden)

    Simon Brežan

    2007-09-01

    Full Text Available Background: Unilateral limb movements are based on the activation of contralateral primary motor cortex and the bilateral activation of premotor cortices. Performance of a visuomotor task requires a visuomotor integration between motor and visual cortical areas. The functional integration (»binding« of different brain areas, is probably mediated by the synchronous neuronal oscillatory activity, which can be determined by electroencephalographic (EEG coherence analysis. We introduced a new method of coherence analysis and compared coherence and power spectra in the left and right hemisphere for the right vs. left hand visuomotor task, hypothesizing that the increase in coherence and decrease in power spectra while performing the task would be greater in the contralateral hemisphere.Methods: We analyzed 6 healthy subjects and recorded their electroencephalogram during visuomotor task with the right or the left hand. For data analysis, a special Matlab computer programme was designed. The results were statistically analysed by a two-way analysis of variance, one-way analysis of variance and post-hoc t-tests with Bonferroni correction.Results: We demonstrated a significant increase in coherence (p < 0.05 for the visuomotor task compared to control tasks in alpha (8–13 Hz in beta 1 (13–20 Hz frequency bands between visual and motor electrodes. There were no significant differences in coherence nor power spectra depending on the hand used. The changes of coherence and power spectra between both hemispheres were symmetrical.Conclusions: In previous studies, a specific increase of coherence and decrease of power spectra for the visuomotor task was found, but we found no conclusive asymmetries when performing the task with right vs. left hand. This could be explained in a way that increases in coherence and decreases of power spectra reflect symmetrical activation and cooperation between more complex visual and motor brain areas.

  18. Performance of a visuomotor walking task in an augmented reality training setting.

    Science.gov (United States)

    Haarman, Juliet A M; Choi, Julia T; Buurke, Jaap H; Rietman, Johan S; Reenalda, Jasper

    2017-12-01

    Visual cues can be used to train walking patterns. Here, we studied the performance and learning capacities of healthy subjects executing a high-precision visuomotor walking task, in an augmented reality training set-up. A beamer was used to project visual stepping targets on the walking surface of an instrumented treadmill. Two speeds were used to manipulate task difficulty. All participants (n = 20) had to change their step length to hit visual stepping targets with a specific part of their foot, while walking on a treadmill over seven consecutive training blocks, each block composed of 100 stepping targets. Distance between stepping targets was varied between short, medium and long steps. Training blocks could either be composed of random stepping targets (no fixed sequence was present in the distance between the stepping targets) or sequenced stepping targets (repeating fixed sequence was present). Random training blocks were used to measure non-specific learning and sequenced training blocks were used to measure sequence-specific learning. Primary outcome measures were performance (% of correct hits), and learning effects (increase in performance over the training blocks: both sequence-specific and non-specific). Secondary outcome measures were the performance and stepping-error in relation to the step length (distance between stepping target). Subjects were able to score 76% and 54% at first try for lower speed (2.3 km/h) and higher speed (3.3 km/h) trials, respectively. Performance scores did not increase over the course of the trials, nor did the subjects show the ability to learn a sequenced walking task. Subjects were better able to hit targets while increasing their step length, compared to shortening it. In conclusion, augmented reality training by use of the current set-up was intuitive for the user. Suboptimal feedback presentation might have limited the learning effects of the subjects. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. View-Invariant Visuomotor Processing in Computational Mirror Neuron System for Humanoid.

    Directory of Open Access Journals (Sweden)

    Farhan Dawood

    Full Text Available Mirror neurons are visuo-motor neurons found in primates and thought to be significant for imitation learning. The proposition that mirror neurons result from associative learning while the neonate observes his own actions has received noteworthy empirical support. Self-exploration is regarded as a procedure by which infants become perceptually observant to their own body and engage in a perceptual communication with themselves. We assume that crude sense of self is the prerequisite for social interaction. However, the contribution of mirror neurons in encoding the perspective from which the motor acts of others are seen have not been addressed in relation to humanoid robots. In this paper we present a computational model for development of mirror neuron system for humanoid based on the hypothesis that infants acquire MNS by sensorimotor associative learning through self-exploration capable of sustaining early imitation skills. The purpose of our proposed model is to take into account the view-dependency of neurons as a probable outcome of the associative connectivity between motor and visual information. In our experiment, a humanoid robot stands in front of a mirror (represented through self-image using camera in order to obtain the associative relationship between his own motor generated actions and his own visual body-image. In the learning process the network first forms mapping from each motor representation onto visual representation from the self-exploratory perspective. Afterwards, the representation of the motor commands is learned to be associated with all possible visual perspectives. The complete architecture was evaluated by simulation experiments performed on DARwIn-OP humanoid robot.

  20. Interhemispheric claustral circuits coordinate somatomotor and visuomotor cortical areas that regulate exploratory behaviors

    Directory of Open Access Journals (Sweden)

    Jared Brent Smith

    2014-05-01

    Full Text Available The claustrum has a role in the interhemispheric transfer of certain types of sensorimotor information. Whereas the whisker region in rat motor (M1 cortex sends dense projections to the contralateral claustrum, the M1 forelimb representation does not. The claustrum sends strong ipsilateral projections to the whisker regions in M1 and somatosensory (S1 cortex, but its projections to the forelimb cortical areas are weak. These distinctions suggest that one function of the M1 projections to the contralateral claustrum is to coordinate the cortical areas that regulate peripheral sensor movements during behaviors that depend on bilateral sensory acquisition. If this hypothesis is true, then similar interhemispheric circuits should interconnect the frontal eye fields (FEF with the contralateral claustrum and its network of projections to vision-related cortical areas. To test this hypothesis, anterograde and retrograde tracers were placed in physiologically-defined parts of the FEF and primary visual cortex (V1 in rats. We observed dense FEF projections to the contralateral claustrum that terminated in the midst of claustral neurons that project to both FEF and V1. While the FEF inputs to the claustrum come predominantly from the contralateral hemisphere, the claustral projections to FEF and V1 are primarily ipsilateral. Detailed comparison of the present results with our previous studies on somatomotor claustral circuitry revealed a well-defined functional topography in which the ventral claustrum is connected with visuomotor cortical areas and the dorsal regions are connected with somatomotor areas. These results suggest that subregions within the claustrum play a critical role in coordinating the cortical areas that regulate the acquisition of modality-specific sensory information during exploration and other behaviors that require sensory attention.

  1. No evidence of a lower visual field specialization for visuomotor control.

    Science.gov (United States)

    Binsted, Gord; Heath, Matthew

    2005-03-01

    The lower visual field (loVF) has been hypothesized to demonstrate specialization for skilled, visually guided action. According to Danckert and Goodale, this visual field asymmetry indirectly suggests that the loVF has privileged connections to visuomotor networks within the dorsal visual pathway. Here we attempted to replicate the loVF advantage during the execution of a discrete aiming movement to targets of various widths (index of difficulty ranging from 1.5 to 5 bits). In addition, we employed trials in which vision of the target object was available or unavailable during the reaching movement to determine whether or not the purported visual field asymmetry reflects enhanced central planning (i.e., feedforward) or online control (i.e., feedback) processes. Reaching trajectories were examined for indicators of online amendments, and movement times and endpoint characteristics were examined to quantify possible visual field asymmetries in relative speed/accuracy trade-offs. In terms of reaching kinematics, it was found that vision of the target during the reaching movement resulted in greater online control of the reaching trajectory; however, no significant main effects or interactions involving visual field were observed. In other words, fixating in the upper or the lower region of peripersonal space did not influence the nature of reaching control (i.e., feedback vs. feedforward). Most importantly, our movement time and endpoint accuracy data elicited a robust speed/accuracy trade-off in both upper and lower regions of working space. Thus, and contrary to previous findings (such as those reported by Danckert and Goodale), the indices of difficulty coupled with the discrete aiming task used here did not elicit a lower visual field advantage for visually guided action.

  2. Prism adaptation differently affects motor-intentional and perceptual-attentional biases in healthy individuals.

    Science.gov (United States)

    Fortis, Paola; Goedert, Kelly M; Barrett, Anna M

    2011-07-01

    Prism adaptation (PA) has been shown to affect performance on a variety of spatial tasks in healthy individuals and neglect patients. However, little is still known about the mechanisms through which PA affects spatial cognition. In the present study we tested the effect of PA on the perceptual-attentional "where" and motor-intentional "aiming" spatial systems in healthy individuals. Eighty-four participants performed a line bisection task presented on a computer screen under normal or right-left reversed viewing conditions, which allows for the fractionation of "where" and "aiming" bias components (Schwartz et al., 1997). The task was performed before and after a short period of visuomotor adaptation either to left- or right-shifting prisms, or control goggles fitted with plain glass lenses. Participants demonstrated initial leftward "where" and "aiming" biases, consistent with previous research. Adaptation to left-shifting prisms reduced the leftward motor-intentional "aiming" bias. By contrast, the "aiming" bias was unaffected by adaptation to the right-shifting prisms or control goggles. The leftward "where" bias was also reduced, but this reduction was independent of the direction of the prismatic shift. These results mirror recent findings in neglect patients, who showed a selective amelioration of right motor-intentional "aiming" bias after right prism exposure (Fortis et al., 2009; C.L. Striemer & J. Danckert, 2010). Thus, these findings indicate that prism adaptation primarily affects the motor-intentional "aiming" system in both healthy individuals and neglect patients, and further suggest that improvement in neglect patients after PA may be related to changes in the aiming spatial system. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Adaptable Design Improvements for Electromagnetic Shock Wave Lithotripters and Techniques for Controlling Cavitation

    Science.gov (United States)

    Smith, Nathan Birchard

    In this dissertation work, the aim was to garner better mechanistic understanding of how shock wave lithotripsy (SWL) breaks stones in order to guide design improvements to modern electromagnetic (EM) shock wave lithotripters. To accomplish this goal, experimental studies were carefully designed to isolate mechanisms of fragmentation, and models for wave propagation, fragmentation, and stone motion were developed. In the initial study, a representative EM lithotripter was characterized and tested for in vitro stone comminution efficiency at a variety of field positions and doses using phantom kidney stones of variable physical properties, and in different fluid mediums to isolate the contribution of cavitation. Through parametric analysis of the acoustic field measurements alongside comminution results, a logarithmic correlation was determined between average peak pressure incident on the stone surface and comminution efficiency. It was also noted that for a given stone type, the correlations converged to an average peak pressure threshold for fragmentation, independent of fluid medium in use. The correlation of average peak pressure to efficacy supports the rationale for the acoustic lens modifications, which were pursued to simultaneously enhance beam width and optimize the pulse profile of the lithotripter shock wave (LSW) via in situ pulse superposition for improved stone fragmentation by stress waves and cavitation, respectively. In parallel, a numerical model for wave propagation was used to investigate the variations of critical parameters with changes in lens geometry. A consensus was reached on a new lens design based on high-speed imaging and stone comminution experiments against the original lens at a fixed acoustic energy setting. The results have demonstrated that the new lens has improved efficacy away from the focus, where stones may move due to respiration, fragmentation, acoustic radiation forces, or voluntary patient movements. Using the

  4. Brain-computer interface analysis of a dynamic visuo-motor task.

    Science.gov (United States)

    Logar, Vito; Belič, Aleš

    2011-01-01

    The area of brain-computer interfaces (BCIs) represents one of the more interesting fields in neurophysiological research, since it investigates the development of the machines that perform different transformations of the brain's "thoughts" to certain pre-defined actions. Experimental studies have reported some successful implementations of BCIs; however, much of the field still remains unexplored. According to some recent reports the phase coding of informational content is an important mechanism in the brain's function and cognition, and has the potential to explain various mechanisms of the brain's data transfer, but it has yet to be scrutinized in the context of brain-computer interface. Therefore, if the mechanism of phase coding is plausible, one should be able to extract the phase-coded content, carried by brain signals, using appropriate signal-processing methods. In our previous studies we have shown that by using a phase-demodulation-based signal-processing approach it is possible to decode some relevant information on the current motor action in the brain from electroencephalographic (EEG) data. In this paper the authors would like to present a continuation of their previous work on the brain-information-decoding analysis of visuo-motor (VM) tasks. The present study shows that EEG data measured during more complex, dynamic visuo-motor (dVM) tasks carries enough information about the currently performed motor action to be successfully extracted by using the appropriate signal-processing and identification methods. The aim of this paper is therefore to present a mathematical model, which by means of the EEG measurements as its inputs predicts the course of the wrist movements as applied by each subject during the task in simulated or real time (BCI analysis). However, several modifications to the existing methodology are needed to achieve optimal decoding results and a real-time, data-processing ability. The information extracted from the EEG could

  5. Self-Adaptive Strategy Based on Fuzzy Control Systems for Improving Performance in Wireless Sensors Networks.

    Science.gov (United States)

    Hernández Díaz, Vicente; Martínez, José-Fernán; Lucas Martínez, Néstor; del Toro, Raúl M

    2015-09-18

    The solutions to cope with new challenges that societies have to face nowadays involve providing smarter daily systems. To achieve this, technology has to evolve and leverage physical systems automatic interactions, with less human intervention. Technological paradigms like Internet of Things (IoT) and Cyber-Physical Systems (CPS) are providing reference models, architectures, approaches and tools that are to support cross-domain solutions. Thus, CPS based solutions will be applied in different application domains like e-Health, Smart Grid, Smart Transportation and so on, to assure the expected response from a complex system that relies on the smooth interaction and cooperation of diverse networked physical systems. The Wireless Sensors Networks (WSN) are a well-known wireless technology that are part of large CPS. The WSN aims at monitoring a physical system, object, (e.g., the environmental condition of a cargo container), and relaying data to the targeted processing element. The WSN communication reliability, as well as a restrained energy consumption, are expected features in a WSN. This paper shows the results obtained in a real WSN deployment, based on SunSPOT nodes, which carries out a fuzzy based control strategy to improve energy consumption while keeping communication reliability and computational resources usage among boundaries.

  6. Self-Adaptive Strategy Based on Fuzzy Control Systems for Improving Performance in Wireless Sensors Networks

    Directory of Open Access Journals (Sweden)

    Vicente Hernández Díaz

    2015-09-01

    Full Text Available The solutions to cope with new challenges that societies have to face nowadays involve providing smarter daily systems. To achieve this, technology has to evolve and leverage physical systems automatic interactions, with less human intervention. Technological paradigms like Internet of Things (IoT and Cyber-Physical Systems (CPS are providing reference models, architectures, approaches and tools that are to support cross-domain solutions. Thus, CPS based solutions will be applied in different application domains like e-Health, Smart Grid, Smart Transportation and so on, to assure the expected response from a complex system that relies on the smooth interaction and cooperation of diverse networked physical systems. The Wireless Sensors Networks (WSN are a well-known wireless technology that are part of large CPS. The WSN aims at monitoring a physical system, object, (e.g., the environmental condition of a cargo container, and relaying data to the targeted processing element. The WSN communication reliability, as well as a restrained energy consumption, are expected features in a WSN. This paper shows the results obtained in a real WSN deployment, based on SunSPOT nodes, which carries out a fuzzy based control strategy to improve energy consumption while keeping communication reliability and computational resources usage among boundaries.

  7. Adaptation to various environments and resistance to disease of the Improved Boer goat.

    Science.gov (United States)

    Erasmus

    2000-05-01

    The Improved Boer Goat is a remarkable small-stock ruminant that possesses distinctive qualities enabling it to excel as an efficient red meat producer. It is early maturing, reaching a mean maximum weight of approximately 62kg at 3.5 years of age on natural pasture under extensive grazing conditions. It boasts high fecundity, with approximately 2.09 kids born per doe kidded. A relatively large proportion of does ( approximately 33%) have triplets, whilst the occurrence of kids born as quadruplets and quintuplets have also been documented. The Boer goat is predominantly a browser, enabling it to convert shrub and bush into red meat, thereby playing a supplementary role to other farm stock in increasing meat production per unit area, rather than being in competition with them. As a browser, the goat is also extremely useful and effective in combatting undesirable bush encroachment. In addition, it appears to be fairly resistant towards certain diseases which are normally contracted by other small stock, such as sheep. Lastly, Boer goats produce red meat of high quality which is hardly distinguishable from that of mutton or lamb as far as flavour is concerned, provided animals are slaughtered at a relatively young age.

  8. [Adaptation to intermittent hypoxia-hyperoxia improves cognitive performance and exercise tolerance in elderly].

    Science.gov (United States)

    Bayer, U; Glazachev, O S; Likar, R; Burtscher, M; Kofler, W; Pinter, G; Stettner, H; Demschar, S; Trummer, B; Neuwersch, S

    2017-01-01

    For improvements in exercise tolerance and cognitive function in geriatric patients Multimodal training programs (MTP) are used as combination of physiotherapy, occupational therapy and cardiovascular training. Intermittent Hypoxic-Hyperoxic Training (IHHT), a modified type of intermittent hypoxic training (IHT) is proposed to be included in MTP to elicit more pronounced beneficial effects in exercise tolerance and cognitive functions of geriatric patients likely by an additional pathway than a single MTP. Thirty four patients of the Geriatric Day Clinic aged between 64 and 92 years participated in the placebo controlled clinical trial. They were randomly assigned to receive MTP plus IHHT (experimental group - EG) or MTP plus placebo-breathing through a machine face mask (control group - CG) in a double blind fashion. Before and after the interventions course cognitive performance was assessed by the Dementia-Detection-Test (DemTect) and the Clock-Drawing-Test (CDT), and functional exercise capacity - by the total distance of 6-Minute-Walk-Test (6MWT). After IHHT combined with MTP cognitive performance (DemTect) increased significantly when compared to NG (+16,7 % vs. +0,39 %, pcognitive performance and exercise capacity in elderly performing MTP. IHHT sessions are considered to be easily applicable to and well tolerated by geriatric patients up to 92 years.

  9. Speed endurance training is a powerful stimulus for physiological adaptations and performance improvements of athletes

    DEFF Research Database (Denmark)

    Iaia, F. M.; Bangsbo, Jens

    2010-01-01

    The present article reviews the physiological and performance effects of speed endurance training consisting of exercise bouts at near maximal intensities in already trained subjects. Despite a reduction in training volume, speed endurance training of endurance-trained athletes can maintain the o......(+) pump activity during exercise may delay fatigue development during intense exercise. In conclusion, athletes from disciplines involving periods of intense exercise can benefit from the inclusion of speed endurance sessions in their training programs.......The present article reviews the physiological and performance effects of speed endurance training consisting of exercise bouts at near maximal intensities in already trained subjects. Despite a reduction in training volume, speed endurance training of endurance-trained athletes can maintain...... performance during longer events, e.g. 40 K cycling and 10 K running. Athletes in team sports involving intense exercise actions and endurance aspects can also benefit from performing speed endurance training. These improvements don't appear to depend on changes in maximum oxygen uptake (VO2max), muscle...

  10. Improved Adaptive Droop Control Design for Optimal Power Sharing in VSC-MTDC Integrating Wind Farms

    Directory of Open Access Journals (Sweden)

    Xiaohong Ran

    2015-07-01

    Full Text Available With the advance of insulated gate bipolar transistor (IGBT converters, Multi-Terminal DC (MTDC based on the voltage-source converter (VSC has developed rapidly in renewable and electric power systems. To reduce the copper loss of large capacity and long distance DC transmission line, an improved droop control design based on optimal power sharing in VSC-MTDC integrating offshore wind farm is proposed. The proposed approach provided a calculation method for power-voltage droop coefficients under two different scenarios either considering local load or not. The available headroom of each converter station was considered as a converter outage, to participate in the power adjustment according to their ability. A four-terminal MTDC model system including two large scale wind farms was set up in PSCAD/EMTDC. Then, the proposed control strategy was verified through simulation under the various conditions, including wind speed variation, rectifier outage and inverter outage, and a three-phase short-circuit of the converter.

  11. An adaptive threshold method for improving astrometry of space debris CCD images

    Science.gov (United States)

    Sun, Rong-yu; Zhao, Chang-yin

    2014-06-01

    Optical survey is a main technique for observing space debris, and precisely measuring the positions of space debris is of great importance. Due to several factors, e.g. the angle object normal to the observer, the shape as well as the attitude of the object, the variations of observed characteristics for low earth orbital space debris are distinct. When we look at optical CCD images of observed objects, the size and brightness are varying, hence it’s difficult to decide the threshold during centroid measurement and precise astrometry. Traditionally the threshold is given empirically and constantly in data reduction, and obviously it’s not suitable for data reduction of space debris. Here we offer a solution to provide the threshold. Our method assumes that the PSF (point spread function) is Gaussian and estimates the signal flux by a directly two-dimensional Gaussian fit, then a cubic spline interpolation is performed to divide each initial pixel into several sub-pixels, at last the threshold is determined by the estimation of signal flux and the sub-pixels above threshold are separated to estimate the centroid. A trail observation of the fast spinning satellite Ajisai is made and the CCD frames are obtained to test our algorithm. The calibration precision of various threshold is obtained through the comparison between the observed equatorial position and the reference one, the latter are obtained from the precise ephemeris of the satellite. The results indicate that our method reduces the total errors of measurements, it works effectively in improving the centering precision of space debris images.

  12. Separating Visual and Motor Components of Motor Cortex Activation for Multiple Reach Targets: A Visuomotor Adaptation Study

    NARCIS (Netherlands)

    Grent-'t Jong, T.; Oostenveld, R.; Medendorp, W.P.; Praamstra, P.

    2015-01-01

    UNLABELLED: Ethologically inspired models of movement preparation view the sensorimotor system as sampling information from the environment in a parallel fashion in preparation for multiple potential actions. In support, the configuration of the physical workspace, manipulated by the number or

  13. Separating Visual and Motor Components of Motor Cortex Activation for Multiple Reach Targets: A Visuomotor Adaptation Study

    NARCIS (Netherlands)

    Grent-'t-Jong, T.; Oostenveld, R.; Medendorp, W.P.; Praamstra, P.

    2015-01-01

    Ethologically inspired models of movement preparation view the sensorimotor system as sampling information from the environment in a parallel fashion in preparation for multiple potential actions. In support, the configuration of the physical workspace, manipulated by the number or spatial

  14. Short-term adaptation during propagation improves the performance of xylose-fermenting Saccharomyces cerevisiae in simultaneous saccharification and co-fermentation.

    Science.gov (United States)

    Nielsen, Fredrik; Tomás-Pejó, Elia; Olsson, Lisbeth; Wallberg, Ola

    2015-01-01

    Inhibitors that are generated during thermochemical pretreatment and hydrolysis impair the performance of microorganisms during fermentation of lignocellulosic hydrolysates. In omitting costly detoxification steps, the fermentation process relies extensively on the performance of the fermenting microorganism. One attractive option of improving its performance and tolerance to microbial inhibitors is short-term adaptation during propagation. This study determined the influence of short-term adaptation on the performance of recombinant Saccharomyces cerevisiae in simultaneous saccharification and co-fermentation (SSCF). The aim was to understand how short-term adaptation with lignocellulosic hydrolysate affects the cell mass yield of propagated yeast and performance in subsequent fermentation steps. The physiology of propagated yeast was examined with regard to viability, vitality, stress responses, and upregulation of relevant genes to identify any links between the beneficial traits that are promoted during adaptation and overall ethanol yields in co-fermentation. The presence of inhibitors during propagation significantly improved fermentation but lowered cell mass yield during propagation. Xylose utilization of adapted cultures was enhanced by increasing amounts of hydrolysate in the propagation. Ethanol yields improved by over 30 % with inhibitor concentrations that corresponded to ≥2.5 % water-insoluble solids (WIS) load during the propagation compared with the unadapted culture. Adaptation improved cell viability by >10 % and increased vitality by >20 %. Genes that conferred resistance against inhibitors were upregulated with increasing amounts of inhibitors during the propagation, but the adaptive response was not associated with improved ethanol yields in SSCF. The positive effects in SSCF were observed even with adaptation at inhibitor concentrations that corresponded to 2.5 % WIS. Higher amounts of hydrolysate in the propagation feed further

  15. Adaptation of voluntary saccades, but not of reactive saccades, transfers to hand pointing movements.

    Science.gov (United States)

    Cotti, Julien; Guillaume, Alain; Alahyane, Nadia; Pelisson, Denis; Vercher, Jean-Louis

    2007-08-01

    Studying the transfer of visuomotor adaptation from a given effector (e.g., the eye) to another (e.g., the hand) allows us to question whether sensorimotor processes influenced by adaptation are common to both effector control systems and thus to address the level where adaptation takes place. Previous studies have shown only very weak transfer of the amplitude adaptation of reactive saccades--i.e., produced automatically in response to the sudden appearance of visual targets--to hand pointing movements. Here we compared the amplitude of hand pointing movements recorded before and after adaptation of either reactive or voluntary saccades, produced either in a saccade sequence task or in a single saccade task. No transfer to hand pointing movements was found after adaptation of reactive saccades. In contrast, a substantial transfer to the hand was obtained following adaptation of voluntary saccades produced in sequence. Large amounts of transfer between the two saccade types were also found. These results demonstrate that the visuomotor processes influenced by saccadic adaptation depend on the type of saccades and that, in the case of voluntary saccades, they are shared by hand pointing movements. Implications for the neurophysiological substrates of the adaptation of reactive and voluntary saccades are discussed.

  16. Improving accuracy and efficiency of mutual information for multi-modal retinal image registration using adaptive probability density estimation.

    Science.gov (United States)

    Legg, P A; Rosin, P L; Marshall, D; Morgan, J E

    2013-01-01

    Mutual information (MI) is a popular similarity measure for performing image registration between different modalities. MI makes a statistical comparison between two images by computing the entropy from the probability distribution of the data. Therefore, to obtain an accurate registration it is important to have an accurate estimation of the true underlying probability distribution. Within the statistics literature, many methods have been proposed for finding the 'optimal' probability density, with the aim of improving the estimation by means of optimal histogram bin size selection. This provokes the common question of how many bins should actually be used when constructing a histogram. There is no definitive answer to this. This question itself has received little attention in the MI literature, and yet this issue is critical to the effectiveness of the algorithm. The purpose of this paper is to highlight this fundamental element of the MI algorithm. We present a comprehensive study that introduces methods from statistics literature and incorporates these for image registration. We demonstrate this work for registration of multi-modal retinal images: colour fundus photographs and scanning laser ophthalmoscope images. The registration of these modalities offers significant enhancement to early glaucoma detection, however traditional registration techniques fail to perform sufficiently well. We find that adaptive probability density estimation heavily impacts on registration accuracy and runtime, improving over traditional binning techniques. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Green tea extract supplementation does not hamper endurance-training adaptation but improves antioxidant capacity in sedentary men.

    Science.gov (United States)

    Kuo, Yu-Chi; Lin, Jung-Charng; Bernard, Jeffrey R; Liao, Yi-Hung

    2015-10-01

    The purpose of this study was to investigate the effect of green tea extract (GTE) supplementation combined with endurance training on endurance capacity and performance in sedentary men. Forty untrained men (age: 20 ± 1 years) participated in this study. Subjects were assigned to 1 of 4 treatments: (i) placebo-control (CTRL), (ii) GTE, (iii) endurance training (Ex), and (iv) endurance training with GTE (ExGTE). During the 4-week intervention, exercise training was prescribed as 75% oxygen uptake reserve for three 20-min sessions per week, and either GTE (250 mg/day) or placebo was provided. Endurance capacity, malondialdehyde (MDA), total antioxidant status (TAS), and creatine kinase (CK) were examined. Ex and ExGTE but not GTE improved exhaustive-run time (Ex: +8.2%, p = 0.031; ExGTE: +14.3%, p training (p = 0.040), and GTE, Ex, and ExGTE markedly attenuated exercise-induced MDA production (p = 0.01, p = 0.005, p = 0.011, respectively). In conclusion, this investigation demonstrated that daily ingestion of GTE during endurance training does not impair improvements in endurance capacity. Moreover, endurance training combined with GTE not only increases antioxidant capacity without attenuating endurance training adaptations, but also further attenuates acute exercise-induced CK release.

  18. Reduction of radiation exposure and improvement of image quality with BMI-adapted prospective cardiac computed tomography and iterative reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Hosch, Waldemar, E-mail: waldemar.hosch@med.uni-heidelberg.de [University of Heidelberg, Department of Diagnostic and Interventional Radiology, Heidelberg (Germany); Stiller, Wolfram [University of Heidelberg, Department of Diagnostic and Interventional Radiology, Heidelberg (Germany); Mueller, Dirk [Philips GmbH Healthcare Division, Hamburg (Germany); Gitsioudis, Gitsios [University of Heidelberg, Department of Cardiology, Heidelberg (Germany); Welzel, Johanna; Dadrich, Monika [University of Heidelberg, Department of Diagnostic and Interventional Radiology, Heidelberg (Germany); Buss, Sebastian J.; Giannitsis, Evangelos [University of Heidelberg, Department of Cardiology, Heidelberg (Germany); Kauczor, Hans U. [University of Heidelberg, Department of Diagnostic and Interventional Radiology, Heidelberg (Germany); Katus, Hugo A. [University of Heidelberg, Department of Cardiology, Heidelberg (Germany); Korosoglou, Grigorios, E-mail: gkorosoglou@hotmail.com [University of Heidelberg, Department of Cardiology, Heidelberg (Germany)

    2012-11-15

    Purpose: To assess the impact of body mass index (BMI)-adapted protocols and iterative reconstruction algorithms (iDose) on patient radiation exposure and image quality in patients undergoing prospective ECG-triggered 256-slice coronary computed tomography angiography (CCTA). Methods: Image quality and radiation exposure were systematically analyzed in 100 patients. 60 Patients underwent prospective ECG-triggered CCTA using a non-tailored protocol and served as a 'control' group (Group 1: 120 kV, 200 mA s). 40 Consecutive patients with suspected coronary artery disease (CAD) underwent prospective CCTA, using BMI-adapted tube voltage and standard (Group 2: 100/120 kV, 100-200 mA s) versus reduced tube current (Group 3: 100/120 kV, 75-150 mA s). Iterative reconstructions were provided with different iDose levels and were compared to filtered back projection (FBP) reconstructions. Image quality was assessed in consensus of 2 experienced observers and using a 5-grade scale (1 = best to 5 = worse), and signal- and contrast-to-noise ratios (SNR and CNR) were quantified. Results: CCTA was performed without adverse events in all patients (n = 100, heart rate of 47-87 bpm and BMI of 19-38 kg/m{sup 2}). Patients examined using the non-tailored protocol in Group 1 had the highest radiation exposure (3.2 {+-} 0.4 mSv), followed by Group 2 (1.7 {+-} 0.7 mSv) and Group 3 (1.2 {+-} 0.6 mSv) (radiation savings of 47% and 63%, respectively, p < 0.001). Iterative reconstructions provided increased SNR and CNR, particularly when higher iDose level 5 was applied with Multi-Frequency reconstruction (iDose5 MFR) (14.1 {+-} 4.6 versus 21.2 {+-} 7.3 for SNR and 12.0 {+-} 4.2 versus 18.1 {+-} 6.6 for CNR, for FBP versus iDose5 MFR, respectively, p < 0.001). The combination of BMI adaptation with iterative reconstruction reduced radiation exposure and simultaneously improved image quality (subjective image quality of 1.4 {+-} 0.4 versus 1.9 {+-} 0.5 for Group 2 reconstructed using

  19. Improving thoracic four-dimensional cone-beam CT reconstruction with anatomical-adaptive image regularization (AAIR)

    Science.gov (United States)

    Shieh, Chun-Chien; Kipritidis, John; O'Brien, Ricky T.; Cooper, Benjamin J.; Kuncic, Zdenka; Keall, Paul J.

    2015-01-01

    Total-variation (TV) minimization reconstructions can significantly reduce noise and streaks in thoracic four-dimensional cone-beam computed tomography (4D CBCT) images compared to the Feldkamp-Davis-Kress (FDK) algorithm currently used in practice. TV minimization reconstructions are, however, prone to over-smoothing anatomical details and are also computationally inefficient. The aim of this study is to demonstrate a proof of concept that these disadvantages can be overcome by incorporating the general knowledge of the thoracic anatomy via anatomy segmentation into the reconstruction. The proposed method, referred as the anatomical-adaptive image regularization (AAIR) method, utilizes the adaptive-steepest-descent projection-onto-convex-sets (ASD-POCS) framework, but introduces an additional anatomy segmentation step in every iteration. The anatomy segmentation information is implemented in the reconstruction using a heuristic approach to adaptively suppress over-smoothing at anatomical structures of interest. The performance of AAIR depends on parameters describing the weighting of the anatomy segmentation prior and segmentation threshold values. A sensitivity study revealed that the reconstruction outcome is not sensitive to these parameters as long as they are chosen within a suitable range. AAIR was validated using a digital phantom and a patient scan and was compared to FDK, ASD-POCS and the prior image constrained compressed sensing (PICCS) method. For the phantom case, AAIR reconstruction was quantitatively shown to be the most accurate as indicated by the mean absolute difference and the structural similarity index. For the patient case, AAIR resulted in the highest signal-to-noise ratio (i.e. the lowest level of noise and streaking) and the highest contrast-to-noise ratios for the tumor and the bony anatomy (i.e. the best visibility of anatomical details). Overall, AAIR was much less prone to over-smoothing anatomical details compared to ASD-POCS and did

  20. Comparison of Population Activity in the Dorsal Premotor Cortex and Putamen During the Learning of Arbitrary Visuomotor Mappings

    Science.gov (United States)

    Buch, Ethan R.; Brasted, Peter J.; Wise, Steven P.

    2005-01-01

    A previous study found that as monkeys learned novel mappings between visual cues and responses, neuronal activity patterns evolved at approximately the same time in both the dorsal premotor cortex (PMd) and the putamen. Here we report that, in both regions, the population activity for novel mappings came to resemble that for familiar ones as learning progressed. Both regions showed activity differences on trials with correct responses versus those with incorrect ones. In addition to these common features, we observed two noteworthy differences between PMd and putamen activity during learning. After a response choice had been made, but prior to feedback about the correctness of that choice (reward or nonreward), the putamen showed a sustained activity increase in activity, whereas PMd did not. Also in the putamen, this prereward activity was highly selective for the specific visuomotor mapping that had just been performed, and this selectivity was maintained until the time of the reward. After performance reached an asymptote, the degree of this selectivity decreased markedly to the level typical for familiar visuomotor mappings. These findings support the hypothesis that neurons in the striatum play a pivotal role in associative learning. PMID:16284756

  1. Improved laser-based triangulation sensor with enhanced range and resolution through adaptive optics-based active beam control.

    Science.gov (United States)

    Reza, Syed Azer; Khwaja, Tariq Shamim; Mazhar, Mohsin Ali; Niazi, Haris Khan; Nawab, Rahma

    2017-07-20

    Various existing target ranging techniques are limited in terms of the dynamic range of operation and measurement resolution. These limitations arise as a result of a particular measurement methodology, the finite processing capability of the hardware components deployed within the sensor module, and the medium through which the target is viewed. Generally, improving the sensor range adversely affects its resolution and vice versa. Often, a distance sensor is designed for an optimal range/resolution setting depending on its intended application. Optical triangulation is broadly classified as a spatial-signal-processing-based ranging technique and measures target distance from the location of the reflected spot on a position sensitive detector (PSD). In most triangulation sensors that use lasers as a light source, beam divergence-which severely affects sensor measurement range-is often ignored in calculations. In this paper, we first discuss in detail the limitations to ranging imposed by beam divergence, which, in effect, sets the sensor dynamic range. Next, we show how the resolution of laser-based triangulation sensors is limited by the interpixel pitch of a finite-sized PSD. In this paper, through the use of tunable focus lenses (TFLs), we propose a novel design of a triangulation-based optical rangefinder that improves both the sensor resolution and its dynamic range through adaptive electronic control of beam propagation parameters. We present the theory and operation of the proposed sensor and clearly demonstrate a range and resolution improvement with the use of TFLs. Experimental results in support of our claims are shown to be in strong agreement with theory.

  2. Food crops face rising temperatures: An overview of responses, adaptive mechanisms, and approaches to improve heat tolerance

    Directory of Open Access Journals (Sweden)

    Neeru Kaushal

    2016-12-01

    Full Text Available The rising temperatures are resulting in heat stress for various agricultural crops to limit their growth, metabolism, and leading to significant loss of yield potential worldwide. Heat stress adversely affects normal plant growth and development depending on the sensitivity of each crop species. Each crop species has its own range of temperature maxima and minima at different developmental stages beyond which all these processes get inhibited. The reproductive stage is on the whole more sensitive to heat stress, resulting in impaired fertilization to cause abortion of flowers. During seed filling, heat stress retards seed growth by affecting all the biochemical events to reduce seed size. Unfavorable temperature may significantly affect photosynthesis, respiration, water balance, and membrane stability of leaves. To combat heat stress, plants acquire various defense mechanisms for their survival such as maintaining membrane stability, and scavenging reactive oxygen species by generating antioxidants and stress proteins. Thermo-tolerance can be improved by the accumulation of various compounds of low molecular mass known as thermo-protectants as well as phyto-hormones. Exogenous application of these molecules has benefited plants growing under heat stress. Alternatively, transgenic plants over-expressing the enzymes catalyzing the synthesis of these molecules may be raised to increase their endogenous levels to improve heat tolerance. In recent times, various transgenics have been developed with improved thermo-tolerance having potential benefits for inducing heat tolerance in food crops. Updated information about of the effects of heat stress on various food crops and their responses as well as adaptive mechanisms is reviewed here.

  3. Adaptation of red blood cell lysis represents a fundamental breakthrough that improves the sensitivity of Salmonella detection in blood

    Science.gov (United States)

    Boyd, MA; Tennant, SM; Melendez, JH; Toema, D; Galen, JE; Geddes, CD; Levine, MM

    2015-01-01

    Aims Isolation of Salmonella Typhi from blood culture is the standard diagnostic for confirming typhoid fever but it is unavailable in many developing countries. We previously described a Microwave Accelerated Metal Enhanced Fluorescence (MAMEF)-based assay to detect Salmonella in medium. Attempts to detect Salmonella in blood were unsuccessful, presumably due to the interference of erythrocytes. The objective of this study was to evaluate various blood treatment methods that could be used prior to PCR, real-time PCR or MAMEF to increase sensitivity of detection of Salmonella. Methods and Results We tested ammonium chloride and erythrocyte lysis buffer, water, Lymphocyte Separation Medium, BD Vacutainer® CPT™ Tubes and dextran. Erythrocyte lysis buffer was the best isolation method as it is fast, inexpensive and works with either fresh or stored blood. The sensitivity of PCR- and real-time PCR detection of Salmonella in spiked blood was improved when whole blood was first lysed using erythrocyte lysis buffer prior to DNA extraction. Removal of erythrocytes and clotting factors also enabled reproducible lysis of Salmonella and fragmentation of DNA, which are necessary for MAMEF sensing. Conclusions Use of the erythrocyte lysis procedure prior to DNA extraction has enabled improved sensitivity of Salmonella detection by PCR and real-time PCR and has allowed lysis and fragmentation of Salmonella using microwave radiation (for future detection by MAMEF). Significance and Impact of the Study Adaptation of the blood lysis method represents a fundamental breakthrough that improves the sensitivity of DNA-based detection of Salmonella in blood. PMID:25630831

  4. Improvement of adaptive GAs and back propagation ANNs performance in condition diagnosis of multiple bearing system using grey relational analysis.

    Science.gov (United States)

    Wulandhari, Lili A; Wibowo, Antoni; Desa, Mohammad I

    2014-01-01

    Condition diagnosis of multiple bearings system is one of the requirements in industry field, because bearings are used in many equipment and their failure can result in total breakdown. Conditions of bearings commonly are reflected by vibration signals data. In multiple bearing condition diagnosis, it will involve many types of vibration signals data; thus, consequently, it will involve many features extraction to obtain precise condition diagnosis. However, large number of features extraction will increase the complexity of the diagnosis system. Therefore, in this paper, we presented a diagnosis method which is hybridization of adaptive genetic algorithms (AGAs), back propagation neural networks (BPNNs), and grey relational analysis (GRA) to diagnose the condition of multiple bearings system. AGAs are used in the diagnosis algorithm to determine the best initial weights of BPNNs in order to improve the diagnosis accuracy. In addition, GRA is applied to determine and select the dominant features from the vibration signal data which will provide good diagnosis of multiple bearings system in less features extraction. The experiments results show that AGAs-BPNNs with GRA approaches can increase the accuracy of diagnosis in shorter processing time, compared with the AGAs-BPNNs without the GRA.

  5. AAV-mediated RLBP1 gene therapy improves the rate of dark adaptation in Rlbp1 knockout mice

    Directory of Open Access Journals (Sweden)

    Vivian W Choi

    Full Text Available Recessive mutations in RLBP1 cause a form of retinitis pigmentosa in which the retina, before its degeneration leads to blindness, abnormally slowly recovers sensitivity after exposure to light. To develop a potential gene therapy for this condition, we tested multiple recombinant adeno-associated vectors (rAAVs composed of different promoters, capsid serotypes, and genome conformations. We generated rAAVs in which sequences from the promoters of the human RLBP1, RPE65, or BEST1 genes drove the expression of a reporter gene (green fluorescent protein. A promoter derived from the RLBP1 gene mediated expression in the retinal pigment epithelium and Müller cells (the intended target cell types at qualitatively higher levels than in other retinal cell types in wild-type mice and monkeys. With this promoter upstream of the coding sequence of the human RLBP1 gene, we compared the potencies of vectors with an AAV2 versus an AAV8 capsid in transducing mouse retinas, and we compared vectors with a self-complementary versus a single-stranded genome. The optimal vector (scAAV8-pRLBP1-hRLBP1 had serotype 8 capsid and a self-complementary genome. Subretinal injection of scAAV8-pRLBP1-hRLBP1 in Rlbp1 nullizygous mice improved the rate of dark adaptation based on scotopic (rod-plus-cone and photopic (cone electroretinograms (ERGs. The effect was still present after 1 year.

  6. Improving high carbon dioxide tolerance and carbon dioxide fixation capability of Chlorella sp. by adaptive laboratory evolution.

    Science.gov (United States)

    Li, Dengjin; Wang, Liang; Zhao, Quanyu; Wei, Wei; Sun, Yuhan

    2015-06-01

    CO2 capture by microalgae is a promising method to reduce greenhouse gas emissions. It is critical to construct a highly efficient way to obtain a microalgal strain tolerant to high CO2 concentrations with high CO2 fixation capability. In this study, two evolved Chlorella sp. strains, AE10 and AE20 were obtained after 31 cycles of adaptive laboratory evolution (ALE) under 10% and 20% CO2, respectively. Both of them grew rapidly in 30% CO2 and the maximal biomass concentration of AE10 was 3.68±0.08g/L, which was 1.22 and 2.94 times to those of AE20 and original strain, respectively. The chlorophyll contents of AE10 and AE20 were significantly higher than those of the original one under 1-30% CO2. The influences of ALE process on biochemical compositions of Chlorella cells were also investigated. This study proved that ALE was an effective approach to improve high CO2 tolerance of Chlorella sp. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. An Alternative Evacuation Framework to Improve Protective-action Strategies Following a Nuclear Power Accident: The Adaptive Protective Action Zone

    Science.gov (United States)

    Hammond, Gregory D.

    Within the U.S. current protective-action strategies to safeguard the public following a nuclear power accident have remained largely unchanged since their implementation in the early 1980s. In the past thirty years, new technologies have been introduced allowing faster computations, better modeling of predicted radiological consequences, and improved accident mapping with geographic information systems (GIS). Utilizing these new technologies, we evaluate the efficacy of alternative strategies, called adaptive protective action zones (APAZs), that use site-specific and event-specific data to dynamically determine evacuation boundaries with simple heuristics in order to better inform protective action decisions (rather than relying on pre-event regulatory bright lines). Several candidate APAZs were developed and then compared to the Nuclear Regulatory Commission's keyhole evacuation strategy (and full evacuation of the emergency planning zone). Two of the APAZs were better on average than existing NRC strategies at reducing either the radiological exposure, the population evacuated, or both. These APAZs are especially effective for larger radioactive plumes and at high population sites; one of them is better at reducing radiation exposure, while the other is better at reducing the population evacuated. However, should policy makers decide that the benefits of APAZs outweigh the costs of implementation, APAZ adoption by U.S. regulatory agencies should be accompanied by a revision to the nuclear-power plant emergency planning basis, and revisions to local nuclear power emergency response planning areas.

  8. Image quality improvement in adaptive optics scanning laser ophthalmoscopy assisted capillary visualization using B-spline-based elastic image registration.

    Science.gov (United States)

    Uji, Akihito; Ooto, Sotaro; Hangai, Masanori; Arichika, Shigeta; Yoshimura, Nagahisa

    2013-01-01

    To investigate the effect of B-spline-based elastic image registration on adaptive optics scanning laser ophthalmoscopy (AO-SLO)-assisted capillary visualization. AO-SLO videos were acquired from parafoveal areas in the eyes of healthy subjects and patients with various diseases. After nonlinear image registration, the image quality of capillary images constructed from AO-SLO videos using motion contrast enhancement was compared before and after B-spline-based elastic (nonlinear) image registration performed using ImageJ. For objective comparison of image quality, contrast-to-noise ratios (CNRS) for vessel images were calculated. For subjective comparison, experienced ophthalmologists ranked images on a 5-point scale. All AO-SLO videos were successfully stabilized by elastic image registration. CNR was significantly higher in capillary images stabilized by elastic image registration than in those stabilized without registration. The average ratio of CNR in images with elastic image registration to CNR in images without elastic image registration was 2.10 ± 1.73, with no significant difference in the ratio between patients and healthy subjects. Improvement of image quality was also supported by expert comparison. Use of B-spline-based elastic image registration in AO-SLO-assisted capillary visualization was effective for enhancing image quality both objectively and subjectively.

  9. Cross Layer Adaptation of Check Intervals in Low Power Listening MAC Protocols for Lifetime Improvement in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Maria-Cristina Marinescu

    2012-08-01

    Full Text Available Preamble sampling-based MAC protocols designed forWireless Sensor Networks (WSN are aimed at prolonging the lifetime of the nodes by scheduling their times of activity. This scheduling exploits node synchronization to find the right trade-off between energy consumption and delay. In this paper we consider the problem of node synchronization in preamble sampling protocols. We propose Cross Layer Adaptation of Check intervals (CLAC, a novel protocol intended to reduce the energy consumption of the nodes without significantly increasing the delay. Our protocol modifies the scheduling of the nodes based on estimating the delay experienced by a packet that travels along a multi-hop path. CLAC uses routing and MAC layer information to compute a delay that matches the packet arrival time. We have implemented CLAC on top of well-known routing and MAC protocols for WSN, and we have evaluated our implementation using the Avrora simulator. The simulation results confirm that CLAC improves the network lifetime at no additional packet loss and without affecting the end-to-end delay.

  10. Adapting source grid parameters to improve the condition of the magnetostatic linear inverse problem of estimating nanoparticle distributions.

    Science.gov (United States)

    Eichardt, Roland; Baumgarten, Daniel; Petković, Bojana; Wiekhorst, Frank; Trahms, Lutz; Haueisen, Jens

    2012-10-01

    The problem of estimating magnetic nanoparticle distributions from magnetorelaxometric measurements is addressed here. The objective of this work was to identify source grid parameters that provide a good condition for the related linear inverse problem. The parameters investigated here were the number of sources, the extension of the source grid, and the source direction. A new measure of the condition, the ratio between the largest and mean singular value of the lead field matrix, is proposed. Our results indicated that the source grids should be larger than the sensor area. The sources and, consequently, the magnetic excitation field, should be directed toward the Z-direction. For underdetermined linear inverse problems, such as in our application, the number of sources affects the condition to a relatively small degree. Overdetermined magnetostatic linear inverse problems, however, benefit from a reduction in the number of sources, which considerably improves the condition. The adapted source grids proposed here were used to estimate the magnetostatic dipole from simulated data; the L2-norm, residual, and distances between the estimated and simulated sources were significantly reduced.

  11. Adaptive Iterative Dose Reduction Using Three Dimensional Processing (AIDR3D improves chest CT image quality and reduces radiation exposure.

    Directory of Open Access Journals (Sweden)

    Tsuneo Yamashiro

    Full Text Available To assess the advantages of Adaptive Iterative Dose Reduction using Three Dimensional Processing (AIDR3D for image quality improvement and dose reduction for chest computed tomography (CT.Institutional Review Boards approved this study and informed consent was obtained. Eighty-eight subjects underwent chest CT at five institutions using identical scanners and protocols. During a single visit, each subject was scanned using different tube currents: 240, 120, and 60 mA. Scan data were converted to images using AIDR3D and a conventional reconstruction mode (without AIDR3D. Using a 5-point scale from 1 (non-diagnostic to 5 (excellent, three blinded observers independently evaluated image quality for three lung zones, four patterns of lung disease (nodule/mass, emphysema, bronchiolitis, and diffuse lung disease, and three mediastinal measurements (small structure visibility, streak artifacts, and shoulder artifacts. Differences in these scores were assessed by Scheffe's test.At each tube current, scans using AIDR3D had higher scores than those without AIDR3D, which were significant for lung zones (p<0.0001 and all mediastinal measurements (p<0.01. For lung diseases, significant improvements with AIDR3D were frequently observed at 120 and 60 mA. Scans with AIDR3D at 120 mA had significantly higher scores than those without AIDR3D at 240 mA for lung zones and mediastinal streak artifacts (p<0.0001, and slightly higher or equal scores for all other measurements. Scans with AIDR3D at 60 mA were also judged superior or equivalent to those without AIDR3D at 120 mA.For chest CT, AIDR3D provides better image quality and can reduce radiation exposure by 50%.

  12. Individual differences in implicit motor learning: task specificity in sensorimotor adaptation and sequence learning.

    Science.gov (United States)

    Stark-Inbar, Alit; Raza, Meher; Taylor, Jordan A; Ivry, Richard B

    2017-01-01

    In standard taxonomies, motor skills are typically treated as representative of implicit or procedural memory. We examined two emblematic tasks of implicit motor learning, sensorimotor adaptation and sequence learning, asking whether individual differences in learning are correlated between these tasks, as well as how individual differences within each task are related to different performance variables. As a prerequisite, it was essential to establish the reliability of learning measures for each task. Participants were tested twice on a visuomotor adaptation task and on a sequence learning task, either the serial reaction time task or the alternating reaction time task. Learning was evident in all tasks at the group level and reliable at the individual level in visuomotor adaptation and the alternating reaction time task but not in the serial reaction time task. Performance variability was predictive of learning in both domains, yet the relationship was in the opposite direction for adaptation and sequence learning. For the former, faster learning was associated with lower variability, consistent with models of sensorimotor adaptation in which learning rates are sensitive to noise. For the latter, greater learning was associated with higher variability and slower reaction times, factors that may facilitate the spread of activation required to form predictive, sequential associations. Interestingly, learning measures of the different tasks were not correlated. Together, these results oppose a shared process for implicit learning in sensorimotor adaptation and sequence learning and provide insight into the factors that account for individual differences in learning within each task domain. We investigated individual differences in the ability to implicitly learn motor skills. As a prerequisite, we assessed whether individual differences were reliable across test sessions. We found that two commonly used tasks of implicit learning, visuomotor adaptation and the

  13. The combined effects of action observation and passive proprioceptive training on adaptive motor learning.

    Science.gov (United States)

    Lei, Yuming; Bao, Shancheng; Wang, Jinsung

    2016-09-07

    Sensorimotor adaptation can be induced by action observation, and also by passive training. Here, we investigated the effect of a protocol that combined action observation and passive training on visuomotor adaptation, by comparing it with the effect of action observation or passive training alone. Subjects were divided into five conditions during the training session: (1) action observation, in which the subjects watched a video of a model who adapted to a novel visuomotor rotation; (2) proprioceptive training, in which the subject's arm was moved passively to target locations that were associated with desired trajectories; (3) combined training, in which the subjects watched the video of a model during a half of the session and experienced passive movements during the other half; (4) active training, in which the subjects adapted actively to the rotation; and (5) a control condition, in which the subjects did not perform any task. Following that session, all subjects adapted to the same visuomotor rotation. Results showed that the subjects in the combined training condition adapted to the rotation significantly better than those in the observation or proprioceptive training condition, although their performance was not as good as that of those who adapted actively. These findings suggest that although a protocol that combines action observation and passive training consists of all the processes involved in active training (error detection and correction, effector-specific and proprioceptively based reaching movements), these processes in that protocol may work differently as compared to a protocol in which the same processes are engaged actively. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  14. Right prefrontal cortex transcranial direct current stimulation enhances multi-day savings in sensorimotor adaptation.

    Science.gov (United States)

    Seidler, Rachael D; Gluskin, Brittany S; Greeley, Brian

    2017-01-01

    We have previously reported that visuospatial working memory performance and magnitude of activation in the right dorsolateral prefrontal cortex predict the rate of visuomotor adaptation. Recent behavioral studies suggest that sensorimotor savings, or faster relearning on second exposure to a task, are due to recall of these early, strategic components of adaptation. In the present study we applied anodal transcranial direct current stimulation to right or left prefrontal cortex or left motor cortex. We found that all groups adapted dart throwing movements while wearing prism lenses at the same rate as subjects receiving sham stimulation on day 1 On test day 2, which was conducted a few days later, the right prefrontal and left motor cortex groups adapted faster than the sham group. Moreover, only the right prefrontal group exhibited greater savings, expressed as a greater difference between day 1 and day 2 errors, compared with sham stimulation. These findings support the hypothesis that the right prefrontal cortex contributes to sensorimotor adaptation and savings. We have previously reported that visuospatial working memory performance and magnitude of activation in the right dorsolateral prefrontal cortex predict the rate of manual visuomotor adaptation. Sensorimotor savings, or faster adaptation to a previously experienced perturbation, has been recently linked to cognitive processes. We show that facilitating the right prefrontal cortex with anodal transcranial direct current stimulation enhances sensorimotor savings compared with sham stimulation. Copyright © 2017 the American Physiological Society.

  15. Infrequent dream recall associated with low performance but high overnight improvement on mirror-tracing.

    Science.gov (United States)

    Dumel, Gaëlle; Carr, Michelle; Marquis, Louis-Philippe; Blanchette-Carrière, Cloé; Paquette, Tyna; Nielsen, Tore

    2015-08-01

    Although sleep facilitates learning and memory, the roles of dreaming and habitual levels of recalling dreams remain unknown. This study examined if performance and overnight improvement on a rapid eye movement sleep-sensitive visuomotor task is associated differentially with habitually high or low dream recall frequency. As a relation between dream production and visuospatial skills has been demonstrated previously, one possibility is that frequency of dream recall will be linked to performance on visuomotor tasks such as the Mirror Tracing Task. We expected that habitually low dream recallers would perform more poorly on the Mirror Tracing Task than would high recallers and would show less task improvement following a night of sleep. Fifteen low and 20 high dream recallers slept one night each in the laboratory and performed the Mirror Tracing Task before and after sleep. Low recallers had overall worse baseline performance but a greater evening-to-morning improvement than did high recallers. Greater improvements in completion time in low recallers were associated with Stage 2 rather than rapid eye movement sleep. Findings support the separate notions that dreaming is related to visuomotor processes and that different levels of visuomotor skill engage different sleep- and dream-related consolidation mechanisms. © 2015 European Sleep Research Society.

  16. The importance of training strategy adaptation: a learner-oriented approach for improving older adults' memory and transfer.

    Science.gov (United States)

    Bottiroli, Sara; Cavallini, Elena; Dunlosky, John; Vecchi, Tomaso; Hertzog, Christopher

    2013-09-01

    We investigated the benefits of strategy-adaptation training for promoting transfer effects. This learner-oriented approach--which directly encourages the learner to generalize strategic behavior to new tasks--helps older adults appraise new tasks and adapt trained strategies to them. In Experiment 1, older adults in a strategy-adaptation training group used 2 strategies (imagery and sentence generation) while practicing 2 tasks (list and associative learning); they were then instructed on how to do a simple task analysis to help them adapt the trained strategies for 2 different unpracticed tasks (place learning and text learning) that were discussed during training. Two additional criterion tasks (name-face associative learning and grocery-list learning) were never mentioned during training. Two other groups were included: A strategy training group (who received strategy training and transfer instructions but not strategy-adaptation training) and a waiting-list control group. Both training procedures enhanced older adults' performance on the trained tasks and those tasks that were discussed during training, but transfer was greatest after strategy-adaptation training. Experiment 2 found that strategy-adaptation training conducted via a manual that older adults used at home also promoted transfer. These findings demonstrate the importance of adopting a learner-oriented approach to promote transfer of strategy training. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  17. Phonological memory in sign language relies on the visuomotor neural system outside the left hemisphere language network.

    Science.gov (United States)

    Kanazawa, Yuji; Nakamura, Kimihiro; Ishii, Toru; Aso, Toshihiko; Yamazaki, Hiroshi; Omori, Koichi

    2017-01-01

    Sign language is an essential medium for everyday social interaction for deaf people and plays a critical role in verbal learning. In particular, language development in those people should heavily rely on the verbal short-term memory (STM) via sign language. Most previous studies compared neural activations during signed language processing in deaf signers and those during spoken language processing in hearing speakers. For sign language users, it thus remains unclear how visuospatial inputs are converted into the verbal STM operating in the left-hemisphere language network. Using functional magnetic resonance imaging, the present study investigated neural activation while bilinguals of spoken and signed language were engaged in a sequence memory span task. On each trial, participants viewed a nonsense syllable sequence presented either as written letters or as fingerspelling (4-7 syllables in length) and then held the syllable sequence for 12 s. Behavioral analysis revealed that participants relied on phonological memory while holding verbal information regardless of the type of input modality. At the neural level, this maintenance stage broadly activated the left-hemisphere language network, including the inferior frontal gyrus, supplementary motor area, superior temporal gyrus and inferior parietal lobule, for both letter and fingerspelling conditions. Interestingly, while most participants reported that they relied on phonological memory during maintenance, direct comparisons between letters and fingers revealed strikingly different patterns of neural activation during the same period. Namely, the effortful maintenance of fingerspelling inputs relative to letter inputs activated the left superior parietal lobule and dorsal premotor area, i.e., brain regions known to play a role in visuomotor analysis of hand/arm movements. These findings suggest that the dorsal visuomotor neural system subserves verbal learning via sign language by relaying gestural inputs to

  18. Visuo-motor coordination ability predicts performance with brain-computer interfaces controlled by modulation of sensorimotor rhythms (SMR

    Directory of Open Access Journals (Sweden)

    Eva Maria Hammer

    2014-08-01

    Full Text Available Modulation of sensorimotor rhythms (SMR was suggested as a control signal for brain-computer interfaces (BCI. Yet, there is a population of users estimated between 10 to 50% not able to achieve reliable control and only about 20% of users achieve high (80-100% performance. Predicting performance prior to BCI use would facilitate selection of the most feasible system for an individual, thus constitute a practical benefit for the user, and increase our knowledge about the correlates of BCI control. In a recent study, we predicted SMR-BCI performance from psychological variables that were assessed prior to the BCI sessions and BCI control was supported with machine-learning techniques. We described two significant psychological predictors, namely the visuo-motor coordination ability and the ability to concentrate on the task. The purpose of the current study was to replicate these results thereby validating these predictors within a neurofeedback based SMR-BCI that involved no machine learning. Thirty-three healthy BCI novices participated in a calibration session and three further neurofeedback training sessions. Two variables were related with mean SMR-BCI performance: (1 A measure for the accuracy of fine motor skills, i.e. a trade for a person’s visuo-motor control ability and (2 subject’s attentional impulsivity. In a linear regression they accounted for almost 20% in variance of SMR-BCI performance, but predictor (1 failed significance. Nevertheless, on the basis of our prior regression model for sensorimotor control ability we could predict current SMR-BCI performance with an average prediction error of M = 12.07%. In more than 50% of the participants, the prediction error was smaller than 10%. Hence, psychological variables played a moderate role in predicting SMR-BCI performance in a neurofeedback approach that involved no machine learning. Future studies are needed to further consolidate (or reject the present predictors.

  19. Visuomotor discordance during visually-guided hand movement in virtual reality modulates sensorimotor cortical activity in healthy and hemiparetic subjects.

    Science.gov (United States)

    Tunik, Eugene; Saleh, Soha; Adamovich, Sergei V

    2013-03-01

    We investigated neural effects of visuomotor discordances during visually-guided finger movements. A functional magnetic resonance imaging (fMRI)-compatible data glove was used to actuate (in real-time) virtual hand models shown on a display in first person perspective. In Experiment 1, we manipulated virtual hand motion to simulate either hypometric or unintentional (actuation of a mismatched finger) feedback of sequential finger flexion in healthy subjects. Analysis of finger motion revealed no significant differences in movement behavior across conditions, suggesting that between-condition differences in brain activity could only be attributed to varying modes of visual feedback rather than motor output. Hypometric feedback and mismatched finger feedback (relative to veridical) were associated with distinct activation. Hypometric feedback was associated with activation in the contralateral motor cortex. Mismatched feedback was associated with activation in bilateral ventral premotor, left dorsal premotor, and left occipitotemporal cortex. The time it took the subject to evaluate visuomotor discordance was positively correlated with activation in bilateral supplementary motor area, bilateral insula, right postcentral gyrus, bilateral dorsal premotor areas, and bilateral posterior parietal lobe. In Experiment 2, we investigated the effects of hypo- and hypermetric visual feedback in three stroke subjects. We observed increased activation of ipsilesional motor cortex in both hypometric and hypermetric feedback conditions. Our data indicate that manipulation of visual feedback of one's own hand movement may be used to facilitate activity in select brain networks. We suggest that these effects can be exploited in neurorehabilition to enhance the processes of brain reorganization after injury and, specifically, might be useful in aiding recovery of hand function in patients during virtual reality-based training.

  20. Improving education due to the need to adapt it to the requirements of the economic development and of the labor market - issues of past history and contemporary features

    Directory of Open Access Journals (Sweden)

    Cornelia Nistor

    2015-12-01

    Full Text Available Improving education has been and continues to be a necessary condition in any society. Education contributes to increase the level of civilization, to develop the individual personality, but also to increase the level of the economic development. Organization and subsequent reorganization of the Romanian education system has been pursuing desiring to adapt better it better to the labor market needs and to adapt it to the international education system. The management strategies which are applied in this area should be considered adapting it to the domestic and international labor market conditions to the new education methods and techniques, used at the international level. The new trends desiring to transform the economy into a green economy require increased investments in education, in order to train the specialists in new green areas.

  1. Prediction of flood abnormalities for improved public safety using a modified adaptive neuro-fuzzy inference system.

    Science.gov (United States)

    Aqil, M; Kita, I; Yano, A; Nishiyama, S

    2006-01-01

    It is widely accepted that an efficient flood alarm system may significantly improve public safety and mitigate economical damages caused by inundations. In this paper, a modified adaptive neuro-fuzzy system is proposed to modify the traditional neuro-fuzzy model. This new method employs a rule-correction based algorithm to replace the error back propagation algorithm that is employed by the traditional neuro-fuzzy method in backward pass calculation. The final value obtained during the backward pass calculation using the rule-correction algorithm is then considered as a mapping function of the learning mechanism of the modified neuro-fuzzy system. Effectiveness of the proposed identification technique is demonstrated through a simulation study on the flood series of the Citarum River in Indonesia. The first four-year data (1987 to 1990) was used for model training/calibration, while the other remaining data (1991 to 2002) was used for testing the model. The number of antecedent flows that should be included in the input variables was determined by two statistical methods, i.e. autocorrelation and partial autocorrelation between the variables. Performance accuracy of the model was evaluated in terms of two statistical indices, i.e. mean average percentage error and root mean square error. The algorithm was developed in a decision support system environment in order to enable users to process the data. The decision support system is found to be useful due to its interactive nature, flexibility in approach, and evolving graphical features, and can be adopted for any similar situation to predict the streamflow. The main data processing includes gauging station selection, input generation, lead-time selection/generation, and length of prediction. This program enables users to process the flood data, to train/test the model using various input options, and to visualize results. The program code consists of a set of files, which can be modified as well to match other

  2. Dynamics of dual prism adaptation: relating novel experimental results to a minimalistic neural model.

    Directory of Open Access Journals (Sweden)

    Orlando Arévalo

    Full Text Available In everyday life, humans interact with a dynamic environment often requiring rapid adaptation of visual perception and motor control. In particular, new visuo-motor mappings must be learned while old skills have to be kept, such that after adaptation, subjects may be able to quickly change between two different modes of generating movements ('dual-adaptation'. A fundamental question is how the adaptation schedule determines the acquisition speed of new skills. Given a fixed number of movements in two different environments, will dual-adaptation be faster if switches ('phase changes' between the environments occur more frequently? We investigated the dynamics of dual-adaptation under different training schedules in a virtual pointing experiment. Surprisingly, we found that acquisition speed of dual visuo-motor mappings in a pointing task is largely independent of the number of phase changes. Next, we studied the neuronal mechanisms underlying this result and other key phenomena of dual-adaptation by relating model simulations to experimental data. We propose a simple and yet biologically plausible neural model consisting of a spatial mapping from an input layer to a pointing angle which is subjected to a global gain modulation. Adaptation is performed by reinforcement learning on the model parameters. Despite its simplicity, the model provides a unifying account for a broad range of experimental data: It quantitatively reproduced the learning rates in dual-adaptation experiments for both direct effect, i.e. adaptation to prisms, and aftereffect, i.e. behavior after removal of prisms, and their independence on the number of phase changes. Several other phenomena, e.g. initial pointing errors that are far smaller than the induced optical shift, were also captured. Moreover, the underlying mechanisms, a local adaptation of a spatial mapping and a global adaptation of a gain factor, explained asymmetric spatial transfer and generalization of prism

  3. Fixed and adaptive beamforming improves speech perception in noise in cochlear implant recipients equipped with the MED-EL SONNET audio processor.

    Science.gov (United States)

    Honeder, Clemens; Liepins, Rudolfs; Arnoldner, Christoph; Šinkovec, Hana; Kaider, Alexandra; Vyskocil, Erich; Riss, Dominik

    2018-01-01

    To determine the impact of the fixed and adaptive beamforming technology of the new MED-EL SONNET cochlear implant audio processor on speech perception in noise. The study cohort comprises 18 postlingually deafened adult cochlear implant recipients with at least six months of experience. Speech reception thresholds were measured with the Oldenburg Sentence Test in continuous, speech-shaped noise. Target sentences were presented in front of the listener, with noise sources placed at -135° and 135°, respectively. Outcome measures were the differences in speech reception threshold using omnidirectional, fixed and adaptive beamformer microphone settings. The use of directional microphones significantly improved speech reception thresholds: fixed beamformer vs. omnidirectional: 4.3 dB (95%-CI [3.1; 5.5]), pprocessor. Cochlear implant users may be able to benefit from improved hearing performance especially in difficult listening situations.

  4. Adaptation Insights

    International Development Research Centre (IDRC) Digital Library (Canada)

    be given greater access to relevant information to help them adapt their farming practices and socio- economic strategies to climate change? To address this challenge, the project “InfoClim,” led by Senegal's. Ecological Monitoring Centre. (CSE) with support from the. CCAA program, aims at improving the access of farmers ...

  5. Adaptive locomotor behavior in larval zebrafish

    Directory of Open Access Journals (Sweden)

    Ruben ePortugues

    2011-08-01

    Full Text Available In this study we report that larval zebrafish display adaptive locomotor output that can be driven by unexpected visual feedback. We develop a new assay that addresses visuomotor integration in restrained larval zebrafish. The assay involves a closed loop environment in which the visual feedback a larva receives depends on its own motor output in a way that resembles freely swimming conditions. The experimenter can control the gain of this closed feedback loop, so that following a given motor output the larva experiences more or less visual feedback depending on whether the gain is high or low. We show that increases and decreases in this gain setting result in adaptive changes in behavior that lead to a generalized decrease or increase of motor output, respectively. Our behavioral analysis shows that both the duration and tail beat frequency of individual swim bouts can be modified, as well as the frequency with which bouts are elicited. These changes can be implemented rapidly, following an exposure to a new gain of just 175 ms. In addition, modifications in some behavioral parameters accumulate over tens of seconds and effects last for at least 30 seconds from trial to trial. These results suggest that larvae establish an internal representation of the visual feedback expected from a given motor output and that the behavioral modifications are driven by an error signal that arises from the discrepancy between this expectation and the actual visual feedback. The assay we develop presents a unique possibility for studying visuomotor integration using imaging techniques available in the larval zebrafish.

  6. An Investigation into the Factors Influencing Extreme-Response Style: Improving Meaning of Translated and Culturally Adapted Rating Scales

    Science.gov (United States)

    Arce-Ferrer, Alvaro J.

    2006-01-01

    Translation and cultural adaptation of rating scales are two critical components in testing culturally and/or linguistically heterogeneous populations. Despite the proper use of these scales, challenges typically arise from respondents' language, culture, ratiocination, and characteristics of measurement processes. This study investigated factors…

  7. Adapting developing country epidemiological assessment techniques to improve the quality of health needs assessments in developed countries

    Directory of Open Access Journals (Sweden)

    Handy Deirdre

    2005-04-01

    Full Text Available Abstract Background We were commissioned to carry out three health assessments in urban areas of Dublin in Ireland. We required an epidemiologically robust method that could collect data rapidly and inexpensively. We were dealing with inadequate health information systems, weak planning data and a history of inadequate recipient involvement in health service planning. These problems had also been identified by researchers carrying out health assessments in developing countries. This paper reports our experience of adapting a cluster survey model originally developed by international organisations to assess community health needs and service coverage in developing countries and applying our adapted model to three urban areas in Dublin, Ireland Methods We adapted the model to control for socio-economic heterogeneity, to take account of the inadequate population list, to ensure a representative sample and to account for a higher prevalence of degenerative and chronic diseases. We employed formal as well as informal communication methods and adjusted data collection times to maximise participation. Results The model we adapted had the capacity to ascertain both health needs and health care delivery needs. The community participated throughout the process and members were trained and employed as data collectors. The assessments have been used by local health boards and non-governmental agencies to plan and deliver better or additional services. Conclusion We were able to carry out high quality health needs assessments in urban areas by adapting and applying a developing country health assessment method. Issues arose relating to health needs assessment as part of the planning cycle and the role of participants in the process.

  8. Visuomotor and motorvisual priming with different types of set-level congruency: evidence in support of ideomotor theory, and the planning and control model (PCM).

    Science.gov (United States)

    Thomaschke, Roland; Miall, R Christopher; Rueß, Miriam; Mehta, Puja R; Hopkins, Brian

    2017-07-29

    Perception can prime action (visuomotor priming), and action can prime perception (motorvisual priming). According to ideomotor theory both effects rely on the overlap of mental representations between perception and action. This implies that both effects get more pronounced the more features they share. We tested this hypothesis by employing in a motorvisual (Exp. 1) and in a visuomotor (Exp. 2) setting, three different pairs of left/right target stimuli (hand pictures, arrows, and words) varying in how strongly they overlap with the pair of left/right responses. For two stimulus pairs (hands and words) the hypothesis was confirmed: hand pictures share more features with the responses than words, consequently hand pictures produced a stronger visuomotor and a stronger motorvisual priming effect than words. However, arrow stimuli showed a different pattern: the temporal dynamics of both priming effects, as well as the direction of the effect seen in motorvisual priming, were significant but opposite to that of the hand and word stimuli. This suggests that the arrows' representations were not involved in ideomotor processes, and we propose instead that they were represented in a spatial or scalar fashion, outside the representations assumed in ideomotor theory. The results are discussed in the context of ideomotor theory, and the planning and control model of motorvisual priming.

  9. How urban system vulnerabilities to flooding could be assessed to improve resilience and adaptation in spatial planning

    Science.gov (United States)

    Pasi, Riccardo; Viavattene, Christophe; La Loggia, Goffredo

    2016-04-01

    Natural hazards damage assets and infrastructure inducing disruptions to urban functions and key daily services. These disruptions may be short or long with a variable spatial scale of impact. From an urban planning perspective, measuring these disruptions and their consequences at an urban scale is fundamental in order to develop more resilient cities. Whereas the assessment of physical vulnerabilities and direct damages is commonly addressed, new methodologies for assessing the systemic vulnerability at the urban scale are required to reveal these disruptions and their consequences. Physical and systemic vulnerability should be measured in order to reflect the multifaceted fragility of cities in the face of external stress, both in terms of the natural/built environment and socio-economic sphere. Additionally, a systemic approach allows the consideration of vulnerability across different spatial scales, as impacts may vary and be transmitted across local, regional or national levels. Urban systems are spatially distributed and the nature of this can have significant effects on flood impacts. The proposed approach identifies the vulnerabilities of flooding within urban contexts, including both in terms of single elementary units (buildings, infrastructures, people, etc.) and systemic functioning (urban functions and daily life networks). Direct losses are appraised initially using conventional methodologies (e.g. depth-damage functions). This aims to both understand the spatial distribution of physical vulnerability and associated losses and, secondly, to identify the most vulnerable building types and ways to improve the physical adaptation of our cities, proposing changes to building codes, design principles and other municipal regulation tools. The subsequent systemic approach recognises the city as a collection of sub-systems or functional units (such as neighbourhoods and suburbs) providing key daily services for inhabitants (e.g. healthcare facilities

  10. Adaptive-predictive organ localization using cone-beam computed tomography for improved accuracy in external beam radiotherapy for bladder cancer.

    Science.gov (United States)

    Lalondrelle, Susan; Huddart, Robert; Warren-Oseni, Karole; Hansen, Vibeke Nordmark; McNair, Helen; Thomas, Karen; Dearnaley, David; Horwich, Alan; Khoo, Vincent

    2011-03-01

    To examine patterns of bladder wall motion during high-dose hypofractionated bladder radiotherapy and to validate a novel adaptive planning method, A-POLO, to prevent subsequent geographic miss. Patterns of individual bladder filling were obtained with repeat computed tomography planning scans at 0, 15, and 30minutes after voiding. A series of patient-specific plans corresponding to these time-displacement points was created. Pretreatment cone-beam computed tomography was performed before each fraction and assessed retrospectively for adaptive intervention. In fractions that would have required intervention, the most appropriate plan was chosen from the patient's "library," and the resulting target coverage was reassessed with repeat cone-beam computed tomography. A large variation in patterns of bladder filling and interfraction displacement was seen. During radiotherapy, predominant translations occurred cranially (maximum 2.5 cm) and anteriorly (maximum 1.75 cm). No apparent explanation was found for this variation using pretreatment patient factors. A need for adaptive planning was demonstrated by 51% of fractions, and 73% of fractions would have been delivered correctly using A-POLO. The adaptive strategy improved target coverage and was able to account for intrafraction motion also. Bladder volume variation will result in geographic miss in a high proportion of delivered bladder radiotherapy treatments. The A-POLO strategy can be used to correct for this and can be implemented from the first fraction of radiotherapy; thus, it is particularly suited to hypofractionated bladder radiotherapy regimens. Copyright © 2011 Elsevier Inc. All rights reserved.

  11. Cross-axis adaptation improves 3D vestibulo-ocular reflex alignment during chronic stimulation via a head-mounted multichannel vestibular prosthesis

    Science.gov (United States)

    Dai, Chenkai; Fridman, Gene Y.; Chiang, Bryce; Davidovics, Natan; Melvin, Thuy-Anh; Cullen, Kathleen E.; Della Santina, Charles C.

    2012-01-01

    By sensing three-dimensional (3D) head rotation and electrically stimulating the three ampullary branches of a vestibular nerve to encode head angular velocity, a multichannel vestibular prosthesis (MVP) can restore vestibular sensation to individuals disabled by loss of vestibular hair cell function. However, current spread to afferent fibers innervating non-targeted canals and otolith endorgans can distort the vestibular nerve activation pattern, causing misalignment between the perceived and actual axis of head rotation. We hypothesized that over time, central neural mechanisms can adapt to correct this misalignment. To test this, we rendered five chinchillas vestibular-deficient via bilateral gentamicin treatment and unilaterally implanted them with a head mounted MVP. Comparison of 3D angular vestibulo-ocular reflex (aVOR) responses during 2 Hz, 50°/s peak horizontal sinusoidal head rotations in darkness on the first, third and seventh days of continual MVP use revealed that eye responses about the intended axis remained stable (at about 70% of the normal gain) while misalignment improved significantly by the end of one week of prosthetic stimulation. A comparable time course of improvement was also observed for head rotations about the other two semicircular canal axes and at every stimulus frequency examined (0.2–5 Hz). In addition, the extent of disconjugacy between the two eyes progressively improved during the same time window. These results indicate that the central nervous system rapidly adapts to multichannel prosthetic vestibular stimulation to markedly improve 3D aVOR alignment within the first week after activation. Similar adaptive improvements are likely to occur in other species, including humans. PMID:21374081

  12. Role of the striatum, cerebellum and frontal lobes in the automatization of a repeated visuomotor sequence of movements.

    Science.gov (United States)

    Doyon, J; Laforce, R; Bouchard, G; Gaudreau, D; Roy, J; Poirier, M; Bédard, P J; Bédard, F; Bouchard, J P

    1998-07-01

    Recently, Doyon et al. [20] demonstrated that lesions to both the striatum and to the cerebellum in humans produce a similar deficit in the learning of a repeated visuomotor sequence, which occurs late in the acquisition process. We now report the results of two experiments that were designed to examine whether this impairment was due to a lack of automatization of the repeating sequence of finger movements by using a dual-task paradigm and by testing for long-term retention of this skill. In Experiment 1, the performance of groups of patients with Parkinson's disease, or with damage to the cerebellum or to the frontal lobes, was compared to that of matched control subjects on the Repeated Sequence Test (primary task) and the Brooks' Matrices Test (secondary task). These two tests were administered concomitantly in both early and late learning phases of the visuomotor sequence. Overall, the groups did not differ in their ability to execute the primary task. By contrast, in accordance with the predictions, patients in Stages 2-3 of Parkinson's disease or with a cerebellar lesion failed to reveal the expected increase in performance on the secondary task seen with learning, suggesting that the latter groups of patients did not have access to the same level of residual cognitive resources to complete the matrices compared to controls. In Experiment 2, the same groups of patients and control subjects were retested again 10-18 months later. They were given four blocks of 100 trials each of the repeating sequence task, followed by a questionnaire and a self-generation task that measured their declarative knowledge of that sequence. The results revealed a long-term retention impairment only in patients who changed from Stage I to Stage II of the disease (suggesting further striatal degeneration) during the one-year interval, or who had a cerebellar lesion. By contrast, performance of the three clinical groups did not differ from controls on declarative memory tests. These

  13. An Experimental Investigation of Improving Human Problem-Solving Performance by Guiding Attention and Adaptively Providing Details on Information Displays

    Science.gov (United States)

    2007-04-01

    1S. SUBJECT TERMS cognitive model, empirical studies, information display design , eye tracking 16. SECURITY CLASSIFICATION OF: 17. LIMITATION 18...basic experimental research of how a cognitive model could be applied to adaptive information display design , and how such displays affected human...create a reactive information display design toolkit to make the process of prototyping and evaluating such displays easier in future. 4. Long Term

  14. Effectiveness of an Adaptive Quizzing System as an Institutional-Wide Strategy to Improve Student Learning and Retention.

    Science.gov (United States)

    Simon-Campbell, Eʼ Loria; Phelan, Julia

    2016-01-01

    Exploring ways to help students achieve success in nursing programs is critical to increase retention and the number of nurse graduates. This study examined the impact of an adaptive quizzing system implemented as a strategy to support student persistence and performance measured by use, grades, and graduation. Results indicated that use of the system increased course content mastery and predicted final course grades. Retention and program completion rates were also positively influenced.

  15. Assessment of right ventricular adaptability to loading conditions can improve the timing of listing to transplantation in patients with pulmonary arterial hypertension.

    Science.gov (United States)

    Dandel, Michael; Knosalla, Christoph; Kemper, Dagmar; Stein, Julia; Hetzer, Roland

    2015-03-01

    Right ventricle (RV) performance is load dependent, and right-sided heart failure (RHF) is the main cause of death in pulmonary arterial hypertension (PAH). Prediction of RV worsening for timely identification of patients needing transplantation (Tx) is paramount. Assessment of RV adaptability to load has proved useful in certain clinical circumstances. This study assessed its predictive value for RHF-free and Tx-free outcome with PAH. Between 2006 and 2012, all potential Tx candidates with PAH, without RHF at the first evaluation, were selected for follow-up (except congenital heart diseases). At selection and at each follow-up, N-terminal prohormone brain natriuretic peptide (NT-proBNP) and the 6-minute walk distance were measured, and RV adaptability to load was assessed by echocardiography. Collected data were tested for the ability to predict RV stability and Tx-free survival. During a 12-month to 92-month follow-up, RHF developed in 23 of 79 evaluated patients, despite similar medication and no differences in initial RV size and ejection fraction compared with the patients who remained stable. However, unstable patients had an initially lower RV load-adaptation index and afterload-corrected peak global systolic longitudinal strain-rate values as well as higher RV dyssynchrony, tricuspid regurgitation, and NT-proBNP levels (p ≤ 0.01). At certain cutoff values, these variables appeared predictive for 1-year and 3-year freedom from RHF and 3-year Tx-free survival. An RV load-adaptation index reduction of ≥20% showed the highest predictive value (90.0%) for short-term (≤1 year) RV decompensation. Assessment of RV adaptability to load allows prediction of RV function and Tx-free survival with severe PAH during the next 1 to 3 years. This can improve the timing of listing for Tx. Copyright © 2015 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

  16. IMPROVEMENT OF ACCURACY OF RADIATIVE HEAT TRANSFER DIFFERENTIAL APPROXIMATION METHOD FOR MULTI DIMENSIONAL SYSTEMS BY MEANS OF AUTO-ADAPTABLE BOUNDARY CONDITIONS

    Directory of Open Access Journals (Sweden)

    K. V. Dobrego

    2015-01-01

    Full Text Available Differential approximation is derived from radiation transfer equation by averaging over the solid angle. It is one of the more effective methods for engineering calculations of radia- tive heat transfer in complex three-dimensional thermal power systems with selective and scattering media. The new method for improvement of accuracy of the differential approximation based on using of auto-adaptable boundary conditions is introduced in the paper. The  efficiency  of  the  named  method  is  proved  for  the  test  2D-systems.  Self-consistent auto-adaptable boundary conditions taking into consideration the nonorthogonal component of the incident to the boundary radiation flux are formulated. It is demonstrated that taking in- to consideration of the non- orthogonal incident flux in multi-dimensional systems, such as furnaces, boilers, combustion chambers improves the accuracy of the radiant flux simulations and to more extend in the zones adjacent to the edges of the chamber.Test simulations utilizing the differential approximation method with traditional boundary conditions, new self-consistent boundary conditions and “precise” discrete ordinates method were performed. The mean square errors of the resulting radiative fluxes calculated along the boundary of rectangular and triangular test areas were decreased 1.5–2 times by using auto- adaptable boundary conditions. Radiation flux gaps in the corner points of non-symmetric sys- tems are revealed by using auto-adaptable boundary conditions which can not be obtained by using the conventional boundary conditions.

  17. Measuring the effects through time of the influence of visuomotor and visuotactile synchronous stimulation on a virtual body ownership illusion.

    Science.gov (United States)

    Kokkinara, Elena; Slater, Mel

    2014-01-01

    Previous studies have examined the experience of owning a virtual surrogate body or body part through specific combinations of cross-modal multisensory stimulation. Both visuomotor (VM) and visuotactile (VT) synchronous stimulation have been shown to be important for inducing a body ownership illusion, each tested separately or both in combination. In this study we compared the relative importance of these two cross-modal correlations, when both are provided in the same immersive virtual reality setup and the same experiment. We systematically manipulated VT and VM contingencies in order to assess their relative role and mutual interaction. Moreover, we present a new method for measuring the induced body ownership illusion through time, by recording reports of breaks in the illusion of ownership ('breaks') throughout the experimental phase. The balance of the evidence, from both questionnaires and analysis of the breaks, suggests that while VM synchronous stimulation contributes the greatest to the attainment of the illusion, a disruption of either (through asynchronous stimulation) contributes equally to the probability of a break in the illusion.

  18. Agency over a phantom limb and electromyographic activity on the stump depend on visuomotor synchrony: a case study.

    Science.gov (United States)

    Imaizumi, Shu; Asai, Tomohisa; Kanayama, Noriaki; Kawamura, Mitsuru; Koyama, Shinichi

    2014-01-01

    Most patients, post-amputation, report the experience of a phantom limb. Some even sense voluntary movements when viewing a mirror image of the intact limb superimposed onto the phantom limb. While delayed visual feedback of an action is known to reduce a sense of agency, the effect of delayed visual feedback on phantom motor sensation (i.e., sense of controlling a phantom limb) has not been examined. Using a video-projection system, we examined the effect of delayed visual feedback on phantom motor sensation in an upper-limb amputee (male; left upper-limb amputation). He was instructed to view mirrored video images of his intact hand clasping and unclasping during a phantom limb movement. He then rated the intensity of the phantom motor sensation. Three types of hand movement images were presented as follows: synchronous, asynchronous with a 250-ms delay, and asynchronous with a 500-ms delay. Results showed that phantom motor sensation decreased when the image was delayed by 250 and 500 ms. However, when we instructed the patient to adjust the phase of phantom limb movement to that of the image with a 500-ms delay, phantom motor sensation increased. There was also a positive correlation between intensity of phantom motor sensation and electromyographic (EMG) activity on deltoids at the patient's stump. These results suggest that phantom motor sensation and EMG activity on the stump depend on visuomotor synchrony and top-down effects.

  19. Agency over a phantom limb and electromyographic activity on the stump depend on visuomotor synchrony: a case study

    Science.gov (United States)

    Imaizumi, Shu; Asai, Tomohisa; Kanayama, Noriaki; Kawamura, Mitsuru; Koyama, Shinichi

    2014-01-01

    Most patients, post-amputation, report the experience of a phantom limb. Some even sense voluntary movements when viewing a mirror image of the intact limb superimposed onto the phantom limb. While delayed visual feedback of an action is known to reduce a sense of agency, the effect of delayed visual feedback on phantom motor sensation (i.e., sense of controlling a phantom limb) has not been examined. Using a video-projection system, we examined the effect of delayed visual feedback on phantom motor sensation in an upper-limb amputee (male; left upper-limb amputation). He was instructed to view mirrored video images of his intact hand clasping and unclasping during a phantom limb movement. He then rated the intensity of the phantom motor sensation. Three types of hand movement images were presented as follows: synchronous, asynchronous with a 250-ms delay, and asynchronous with a 500-ms delay. Results showed that phantom motor sensation decreased when the image was delayed by 250 and 500 ms. However, when we instructed the patient to adjust the phase of phantom limb movement to that of the image with a 500-ms delay, phantom motor sensation increased. There was also a positive correlation between intensity of phantom motor sensation and electromyographic (EMG) activity on deltoids at the patient’s stump. These results suggest that phantom motor sensation and EMG activity on the stump depend on visuomotor synchrony and top-down effects. PMID:25120449

  20. Agency over a phantom limb and electromyographic activity on the stump depend on visuomotor synchrony: a case study

    Directory of Open Access Journals (Sweden)

    Shu eImaizumi

    2014-07-01

    Full Text Available Most patients, post-amputation, report the experience of a phantom limb. Some even sense voluntary movements when viewing a mirror image of the intact limb superimposed onto the phantom limb. While delayed visual feedback of an action is known to reduce a sense of agency, the effect of delayed visual feedback on phantom motor sensation (i.e., sense of controlling a phantom limb has not been examined. Using a video-projection system, we examined the effect of delayed visual feedback on phantom motor sensation in an upper-limb amputee (male; left upper-limb amputation. He was instructed to view mirrored video images of his intact hand clasping and unclasping during a phantom limb movement. He then rated the intensity of the phantom motor sensation. Three types of hand movement images were presented as follows: synchronous, asynchronous with a 250-ms delay, and asynchronous with a 500-ms delay. Results showed that phantom motor sensation decreased when the image was delayed by 250 and 500 ms. However, when we instructed the patient to adjust the phase of phantom limb movement to that of the image with a 500-ms delay, phantom motor sensation increased. There was also a positive correlation between intensity of phantom motor sensation and electromyographic activity on deltoids at the patient’s stump. These results suggest that phantom motor sensation and electromyographic activity on the stump depend on visuomotor synchrony and top-down effects.

  1. Improved fatigue resistance in Gsα-deficient and aging mouse skeletal muscles due to adaptive increases in slow fibers

    Science.gov (United States)

    Feng, Han-Zhong; Chen, Min; Weinstein, Lee S.

    2011-01-01

    Genetically modified mice with deficiency of the G protein α-subunit (Gsα) in skeletal muscle showed metabolic abnormality with reduced glucose tolerance, low muscle mass, and low contractile force, along with a fast-to-slow-fiber-type switch (Chen M, Feng HZ, Gupta D, Kelleher J, Dickerson KE, Wang J, Hunt D, Jou W, Gavrilova O, Jin JP, Weinstein LS. Am J Physiol Cell Physiol 296: C930–C940, 2009). Here we investigated a hypothesis that the switching to more slow fibers is an adaptive response with specific benefit. The results showed that, corresponding to the switch of myosin isoforms, the thin-filament regulatory proteins troponin T and troponin I both switched to their slow isoforms in the atrophic soleus muscle of 3-mo-old Gsα-deficient mice. This fiber-type switch involving coordinated changes of both thick- and thin-myofilament proteins progressed in the Gsα-deficient soleus muscles of 18- to 24-mo-old mice, as reflected by the expression of solely slow isoforms of myosin and troponin. Compared with age-matched controls, Gsα-deficient soleus muscles with higher proportion of slow fibers exhibited slower contractile and relaxation kinetics and lower developed force, but significantly increased resistance to fatigue, followed by a better recovery. Gsα-deficient soleus muscles of neonatal and 3-wk-old mice did not show the increase in slow fibers. Therefore, the fast-to-slow-fiber-type switch in Gsα deficiency at older ages was likely an adaptive response. The benefit of higher fatigue resistance in adaption to metabolic deficiency and aging provides a mechanism to sustain skeletal muscle function in diabetic patients and elderly individuals. PMID:21680879

  2. Adaptive cone-beam CT planning improves long-term biochemical disease-free survival for (125)I prostate brachytherapy.

    Science.gov (United States)

    Peters, M; Smit Duijzentkunst, D A; Westendorp, H; van de Pol, S M G; Kattevilder, R; Schellekens, A; van der Voort van Zyp, J R N; Moerland, M A; van Vulpen, M; Hoekstra, C J

    Determining the independent effect of additional intraoperative adaptive C-arm cone-beam CT (CBCT) planning vs. transrectal ultrasound (TRUS)-guided interactive planning alone in (125)I brachytherapy for prostate cancer (PCa) on biochemical disease-free survival (BDFS). T1/T2-stage PCa patients receiving TRUS-guided brachytherapy from 2000 to 2014 were analyzed. From October 2006, patients received additional intraoperative adaptive CBCT planning for dosimetric evaluation and subsequent remedial seed placement in underdosed areas. Patients were stratified according to the National Comprehensive Cancer Network (NCCN) risk classification. Kaplan-Meier analysis was used to estimate BDFS (primary outcome), overall survival, and PCa-specific survival (secondary outcomes). Cox regression was used to assess the relation between CBCT use and biochemical failure (BF) and overall mortality. In all, 1623 patients were included. Median followup was 99 months (interquartile range 70-115) for TRUS patients (n = 613) and 51 months (interquartile range 29-70) for CBCT patients (n = 1010). BF occurred 203 times and 206 patients died, 26 from PCa. For TRUS and CBCT patients, 7-year BDFS was 87.2% vs. 93.5% (log rank: p = 0.04) for low, 75.9% vs. 88.5% (p brachytherapy leads to a significant increase in BDFS in all NCCN risk groups. Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

  3. Adaptive VFH

    Science.gov (United States)

    Odriozola, Iñigo; Lazkano, Elena; Sierra, Basi

    2011-10-01

    This paper investigates the improvement of the Vector Field Histogram (VFH) local planning algorithm for mobile robot systems. The Adaptive Vector Field Histogram (AVFH) algorithm has been developed to improve the effectiveness of the traditional VFH path planning algorithm overcoming the side effects of using static parameters. This new algorithm permits the adaptation of planning parameters for the different type of areas in an environment. Genetic Algorithms are used to fit the best VFH parameters to each type of sector and, afterwards, every section in the map is labelled with the sector-type which best represents it. The Player/Stage simulation platform has been chosen for making all sort of tests and to prove the new algorithm's adequateness. Even though there is still much work to be carried out, the developed algorithm showed good navigation properties and turned out to be softer and more effective than the traditional VFH algorithm.

  4. Dissociating perceptual and motor effects of prism adaptation in neglect.

    Science.gov (United States)

    Striemer, Christopher L; Danckert, James

    2010-04-21

    Prism adaptation reduces some symptoms of neglect; however the mechanisms underlying such changes are poorly understood. We suggest that prisms influence neglect by acting on dorsal stream circuits subserving visuomotor control, with little influence on perceptual aspects of neglect. We examined prism adaptation in three neglect patients and a group of healthy controls on line bisection and landmark tasks. Neglect patients showed a dramatic reduction in the rightward bias for line bisection, but absolutely no change in their leftward bias on the landmark task, which is a perceptual equivalent to bisection. However, in controls, prisms produced 'neglect-like' deficits on both the line bisection and landmark tasks. These data suggest that prisms influence visually guided actions more so than perception in neglect.

  5. Relief of knee flexion contracture and gait improvement following adaptive training for an assist device in a transtibial amputee: A case study.

    Science.gov (United States)

    Kim, Sol-Bi; Ko, Chang-Yong; Son, Jinho; Kang, Sungjae; Ryu, Jeicheong; Mun, Museong

    2017-01-01

    Management of a knee contracture is important for regaining gait ability in transtibial amputees. However, there has been little study of prosthesis training for enhancing mobility and improving range of motion in cases of restricted knee extension. This study aimed to evaluate the effects of adaptive training for an assist device (ATAD) for a transtibial amputee with a knee flexion contracture (KFC). A male transtibial amputee with KFC performed 4 months of ATAD with a multidisciplinary team. During the ATAD, the passive range of motion (PROM) in the knee, amputee mobility predictor (AMP) assessment, center of pressure (COP) on a force plate-equipped treadmill, gait features determined by three-dimensional motion analysis, and Short-Form 36 Item Health Survey (SF-36) scores were evaluated. Following ATAD, PROM showed immediate improvement (135.6 ± 2.4° at baseline, 142.5 ± 1.7° at Step 1, 152.1 ± 1.8° at Step 2, 165.8 ± 1.9° at Step 3, and 166.0 ± 1.4° at Step 4); this was followed by an enhanced COP. Gradually, gait features also improved. Additionally, the AMP score (5 at baseline to 29 at Step 4) and K-level (K0 at baseline to K3 at Step 4) increased after ATAD. Along with these improvements, the SF-36 score also improved. ATAD could be beneficial for transtibial amputees by relieving knee contractures and improving gait.

  6. A Fuzzy-Based Adaptive Streaming Algorithm for Reducing Entropy Rate of DASH Bitrate Fluctuation to Improve Mobile Quality of Service

    Directory of Open Access Journals (Sweden)

    Linh Van Ma

    2017-09-01

    Full Text Available Dynamic adaptive streaming over Hypertext Transfer Protocol (HTTP is an advanced technology in video streaming to deal with the uncertainty of network states. However, this technology has one drawback as the network states frequently and continuously change. The quality of a video streaming fluctuates along with the network changes, and it might reduce the quality of service. In recent years, many researchers have proposed several adaptive streaming algorithms to reduce such changes. However, these algorithms only consider the current state of a network. Thus, these algorithms might result in inaccurate estimates of a video quality in the near term. Therefore, in this paper, we propose a method using fuzzy logic and a mathematics moving average technique, in order to reduce mobile video quality fluctuation in Dynamic Adaptive Streaming over HTTP (DASH. First, we calculate the moving average of the bandwidth and buffer values for a given period. On the basis of differences between real and average values, we propose a fuzzy logic system to deduce the value of the video quality representation for the next request. In addition, we use the entropy rate of a bandwidth measurement sequence to measure the predictable/stabilization of our method. The experiment results show that our proposed method reduces video quality fluctuation as well as improves 40% of bandwidth utilization compared to existing methods.

  7. A culturally adapted telecommunication system to improve physical activity, diet quality, and medication adherence among hypertensive African-Americans: a randomized controlled trial.

    Science.gov (United States)

    Migneault, Jeffrey P; Dedier, Julien J; Wright, Julie A; Heeren, Timothy; Campbell, Marci Kramish; Morisky, Donald E; Rudd, Peter; Friedman, Robert H

    2012-02-01

    Hypertension is more prevalent and clinically severe among African-Americans than whites. Several health behaviors influence blood pressure (BP) control, but effective, accessible, culturally sensitive interventions that target multiple behaviors are lacking. We evaluated a culturally adapted, automated telephone system to help hypertensive, urban African-American adults improve their adherence to their antihypertensive medication regimen and to evidence-based guidelines for dietary behavior and physical activity. We randomized 337 hypertensive primary care patients to an 8-month automated, multi-behavior intervention or to an education-only control. Medication adherence, diet, physical activity, and BP were assessed at baseline and every 4 months for 1 year. Data were analyzed using longitudinal modeling. The intervention was associated with improvements in a measure of overall diet quality (+3.5 points, p telecommunications systems can promote self-management of diet and energy balance in urban African-Americans.

  8. Coping with climate change uncertainty for adaptation planning: An improved criterion for decision making under uncertainty using UKCP09

    Directory of Open Access Journals (Sweden)

    M. Green

    2014-01-01

    Analyses using sub-samples of the complete probabilistic dataset showed that the Green Z-score had comparable reproducibility to Laplace and improved reproducibility compared to other current decision criteria, and unlike Laplace is able to accommodate different risk attitudes.

  9. Managing project complexity : A study into adapting early project phases to improve project performance in large engineering projects

    NARCIS (Netherlands)

    Bosch-Rekveldt, M.G.C.

    2011-01-01

    Engineering projects become increasingly more complex and project complexity is assumed to be one of the causes for projects being delivered late and over budget. However, what this project complexity actually comprised of was unclear. To improve the overall project performance, this study focuses

  10. Studying Implementation within a Continuous Continuous-Improvement Process: What Happens When We Design with Adaptations in Mind?

    Science.gov (United States)

    Tichnor-Wagner, Ariel; Allen, Danielle; Socol, Allison Rose; Cohen-Vogel, Lora; Rutledge, Stacey A.; Xing, Qi W.

    2018-01-01

    Background/Context: This study examines the implementation of an academic and social-emotional learning innovation called Personalization for Academic and Social-Emotional Learning, or PASL. The innovation was designed, tested, and implemented using a continuous continuous-improvement model. The model emphasized a top-and-bottom process in which…

  11. Improved respiratory efficiency of 3D late gadolinium enhancement imaging using the continuously adaptive windowing strategy (CLAWS).

    Science.gov (United States)

    Keegan, Jennifer; Jhooti, Permi; Babu-Narayan, Sonya V; Drivas, Peter; Ernst, Sabine; Firmin, David N

    2014-03-01

    Acquisition durations of navigator-gated high-resolution three-dimensional late gadolinium enhancement studies may typically be up to 10 min, depending on the respiratory efficiency and heart rate. Implementation of the continuously adaptive windowing strategy (CLAWS) could increase respiratory efficiency, but the resulting non-smooth k-space acquisition order during gadolinium wash-out could result in increased artifact. Navigator-gated three-dimensional late gadolinium enhancement acquisitions were performed in 18 patients using tracking end-expiratory accept/reject (EE-ARA) and CLAWS algorithms in random order. Retrospective analysis of the stored navigator data shows that CLAWS scan times are very close to (within 1%) or equal to the fastest achievable scan times while EE-ARA significantly extends the acquisition duration (P Image quality scores for CLAWS and EE-ARA acquisitions are not significantly different (4.1 ± 0.6 compared to 4.3 ± 0.6, P = ns). Numerical phantom simulations show that the non-uniform k-space ordering introduced by CLAWS results in slight, but not statistically significant, reductions in both blood signal-to-noise ratio (10%) and blood-myocardium contrast-to-noise ratio (12%). CLAWS results in markedly reduced acquisition durations compared to EE-ARA without significant detriment to the image quality. Copyright © 2013 Wiley Periodicals, Inc.

  12. Particle system based adaptive sampling on spherical parameter space to improve the MDL method for construction of statistical shape models.

    Science.gov (United States)

    Xu, Rui; Zhou, Xiangrong; Hirano, Yasushi; Tachibana, Rie; Hara, Takeshi; Kido, Shoji; Fujita, Hiroshi

    2013-01-01

    Minimum description length (MDL) based group-wise registration was a state-of-the-art method to determine the corresponding points of 3D shapes for the construction of statistical shape models (SSMs). However, it suffered from the problem that determined corresponding points did not uniformly spread on original shapes, since corresponding points were obtained by uniformly sampling the aligned shape on the parameterized space of unit sphere. We proposed a particle-system based method to obtain adaptive sampling positions on the unit sphere to resolve this problem. Here, a set of particles was placed on the unit sphere to construct a particle system whose energy was related to the distortions of parameterized meshes. By minimizing this energy, each particle was moved on the unit sphere. When the system became steady, particles were treated as vertices to build a spherical mesh, which was then relaxed to slightly adjust vertices to obtain optimal sampling-positions. We used 47 cases of (left and right) lungs and 50 cases of livers, (left and right) kidneys, and spleens for evaluations. Experiments showed that the proposed method was able to resolve the problem of the original MDL method, and the proposed method performed better in the generalization and specificity tests.

  13. Cerebello-Cortical Differences in Effective Connectivity of the Dominant and Non-dominant Hand during a Visuomotor Paradigm of Grip Force Control

    Directory of Open Access Journals (Sweden)

    Eric Moulton

    2017-10-01

    Full Text Available Structural and functional differences are known to exist within the cortical sensorimotor networks with respect to the dominant vs. non-dominant hand. Similarly, the cerebellum, a key structure in the sensorimotor network with its cerebello-cortical connections, has been reported to respond differently when using the dominant vs. non-dominant hand. Several groups have already investigated causal interactions during diverse motor paradigms using effective connectivity but few have studied the larger visuomotor network, including key structures such as the parietal cortex and the cerebellum, with both hands. Moreover, the effect of force level on such interactions is still unclear. We therefore sought to determine the hemispheric asymmetries in the cerebello-cortical sensorimotor network in right-handers at two force levels (5% and 10% maximum voluntary contraction for both hands. Cerebello-cortical modulations were investigated in 28 healthy, right-handed volunteers by determining the effective connectivity during a visuomotor task at two force levels under fMRI. A network was built consisting of the left and right primary motor (M1, ventral premotor (PMv and posterior parietal cortices (PPC, in addition to the supplementary motor area (SMA, and the ipsilateral cerebellum (Cer to the hand performing the motor task. Task performance (precision of isometric grip force tracking did not differ between hands, nor did task-related activations in the sensorimotor areas apart from the contralateral primary motor cortex. However, during visuomotor control of the non-dominant hand, connectivity analysis revealed causal modulations between (i the ipsilateral cerebellum and SMA, and (ii the ipsilatearl cerebellum and contralateral PPC, which was not the case when using the dominant hand. These cerebello-cortical modulations for the non-dominant hand were more present at the higher of the two force levels. We conclude that precision force generation executed

  14. Multisynaptic projections from the ventrolateral prefrontal cortex to the dorsal premotor cortex in macaques - anatomical substrate for conditional visuomotor behavior.

    Science.gov (United States)

    Takahara, Daisuke; Inoue, Ken-Ichi; Hirata, Yoshihiro; Miyachi, Shigehiro; Nambu, Atsushi; Takada, Masahiko; Hoshi, Eiji

    2012-11-01

    Lines of evidence indicate that both the ventrolateral prefrontal cortex (vlPFC) (areas 45/12) and dorsal premotor cortex (PMd) (rostral F2 in area 6) are crucially involved in conditional visuomotor behavior, in which it is required to determine an action based on an associated visual object. However, virtually no direct projections appear to exist between the vlPFC and PMd. In the present study, to elucidate possible multisynaptic networks linking the vlPFC to the PMd, we performed a series of neuroanatomical tract-tracing experiments in macaque monkeys. First, we identified cortical areas that send projection fibers directly to the PMd by injecting Fast Blue into the PMd. Considerable retrograde labeling occurred in the dorsal prefrontal cortex (dPFC) (areas 46d/9/8B/8Ad), dorsomedial motor cortex (dmMC) (F7 and presupplementary motor area), rostral cingulate motor area, and ventral premotor cortex (F5 and area 44), whereas the vlPFC was virtually devoid of neuronal labeling. Second, we injected the rabies virus, a retrograde transneuronal tracer, into the PMd. At 3 days after the rabies injections, second-order neurons were labeled in the vlPFC (mainly area 45), indicating that the vlPFC disynaptically projects to the PMd. Finally, to determine areas that connect the vlPFC to the PMd indirectly, we carried out an anterograde/retrograde dual-labeling experiment in single monkeys. By examining the distribution of axon terminals labeled from the vlPFC and cell bodies labeled from the PMd, we found overlapping labels in the dPFC and dmMC. These results indicate that the vlPFC outflow is directed toward the PMd in a multisynaptic fashion through the dPFC and/or dmMC. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  15. Adaptive and innovative Radiation Treatment FOR improving Cancer treatment outcomE (ARTFORCE); a randomized controlled phase II trial for individualized treatment of head and neck cancer.

    Science.gov (United States)

    Heukelom, Jolien; Hamming, Olga; Bartelink, Harry; Hoebers, Frank; Giralt, Jordi; Herlestam, Teresa; Verheij, Marcel; van den Brekel, Michiel; Vogel, Wouter; Slevin, Nick; Deutsch, Eric; Sonke, Jan-Jakob; Lambin, Philippe; Rasch, Coen

    2013-02-22

    Failure of locoregional control is the main cause of recurrence in advanced head and neck cancer. This multi-center trial aims to improve outcome in two ways. Firstly, by redistribution of the radiation dose to the metabolically most FDG-PET avid part of the tumour. Hereby, a biologically more effective dose distribution might be achieved while simultaneously sparing normal tissues. Secondly, by improving patient selection. Both cisplatin and Epidermal Growth Factor Receptor (EGFR) antibodies like Cetuximab in combination with Radiotherapy (RT) are effective in enhancing tumour response. However, it is unknown which patients will benefit from either agent in combination with irradiation. We will analyze the predictive value of biological markers and (89)Zr-Cetuximab uptake for treatment outcome of chemoradiation with Cetuximab or cisplatin to improve patient selection. ARTFORCE is a randomized phase II trial for 268 patients with a factorial 2 by 2 design: cisplatin versus Cetuximab and standard RT versus redistributed RT. Cisplatin is dosed weekly 40 mg/m(2) for 6 weeks. Cetuximab is dosed 250 mg/m(2) weekly (loading dose 400 mg/m(2)) for 6 weeks. The standard RT regimen consists of elective RT up to 54.25 Gy with a simultaneous integrated boost (SIB) to 70 Gy in 35 fractions in 6 weeks. Redistributed adaptive RT consists of elective RT up to 54.25 Gy with a SIB between 64-80 Gy in 35 fractions in 6 weeks with redistributed dose to the gross tumour volume (GTV) and clinical target volume (CTV), and adaptation of treatment for anatomical changes in the third week of treatment.Patients with locally advanced, biopsy confirmed squamous cell carcinoma of the oropharynx, oral cavity or hypopharynx are eligible.Primary endpoints are: locoregional recurrence free survival at 2 years, correlation of the median (89)Zr-cetuximab uptake and biological markers with treatment specific outcome, and toxicity. Secondary endpoints are quality of life, swallowing function

  16. Farmer innovation driven by needs and understanding: building the capacities of farmer groups for improved cooking stove construction and continued adaptation

    Science.gov (United States)

    Uckert, G.; Hafner, J.; Graef, F.; Hoffmann, H.; Kimaro, A.; Sererya, O.; Sieber, S.

    2017-12-01

    Enhancing food security is one of the main goals of subsistence farmers in Sub-Saharan Africa. This study investigates the implementation of improved loam-made cooking stoves and its contribution to coping and livelihood strategies. Controlled combustion, air as well as smoke flue, and heat insulation facilitate the more efficient fuel consumption of improved cooking stoves compared to traditional stoves—namely three stone fires. Although the majority of small-scale farmers in Sub-Saharan Africa rely on the free public good of firewood, the increasing time needed for collecting firewood implies high opportunity costs for productive members of the family. The primary outcomes for users of improved stoves are reduced fuel consumption, greater safety, saved time, and reduced smoke in the kitchen. The paper illustrates part of the output, outcome, and impact of a participatory action research approach for implementing improved cooking stoves. Special emphasis was put on enabling the villagers to construct their stoves without external support, hence having locally manufactured stoves made of mud, bricks, and dried grass. The impact pathway of improved cooking stoves followed the training-of-trainers concept, where members of the initially established farmer groups were trained to construct stoves on their own. Special focus was given to knowledge exchange and knowledge transfer in order to increase firewood efficiency and overall satisfaction of users of improved cook stoves. Encouraging the members to further adapt the stoves enabled them to scale-up the construction of improved cooked stoves into a business model and increase dissemination while creating income. Although many important benefits, like time and knowledge gain, were identified by the farmers after adoption of the new technology, we found adoption rates differed significantly between regions.

  17. Stay-green traits to improve wheat adaptation in well-watered and water-limited environments

    OpenAIRE

    Christopher, John (Jack) T.; Christopher, Mandy J.; Borrell, Andrew K.; Fletcher, Susan; Chenu, Karine

    2016-01-01

    A stay-green phenotype enables crops to retain green leaves longer after anthesis compared with senescent types, potentially improving yield. Measuring the normalized difference vegetative index (NDVI) during the whole senescence period allows quantification of component stay-green traits contributing to a stay-green phenotype. These objective and standardized traits can be compared across genotypes and environments. Traits examined include maximum NDVI near anthesis (Nmax), senescence rate (...

  18. Development of gradient descent adaptive algorithms to remove common mode artifact for improvement of cardiovascular signal quality.

    Science.gov (United States)

    Ciaccio, Edward J; Micheli-Tzanakou, Evangelia

    2007-07-01

    Common-mode noise degrades cardiovascular signal quality and diminishes measurement accuracy. Filtering to remove noise components in the frequency domain often distorts the signal. Two adaptive noise canceling (ANC) algorithms were tested to adjust weighted reference signals for optimal subtraction from a primary signal. Update of weight w was based upon the gradient term of the steepest descent equation: [see text], where the error epsilon is the difference between primary and weighted reference signals. nabla was estimated from Deltaepsilon(2) and Deltaw without using a variable Deltaw in the denominator which can cause instability. The Parallel Comparison (PC) algorithm computed Deltaepsilon(2) using fixed finite differences +/- Deltaw in parallel during each discrete time k. The ALOPEX algorithm computed Deltaepsilon(2)x Deltaw from time k to k + 1 to estimate nabla, with a random number added to account for Deltaepsilon(2) . Deltaw--> 0 near the optimal weighting. Using simulated data, both algorithms stably converged to the optimal weighting within 50-2000 discrete sample points k even with a SNR = 1:8 and weights which were initialized far from the optimal. Using a sharply pulsatile cardiac electrogram signal with added noise so that the SNR = 1:5, both algorithms exhibited stable convergence within 100 ms (100 sample points). Fourier spectral analysis revealed minimal distortion when comparing the signal without added noise to the ANC restored signal. ANC algorithms based upon difference calculations can rapidly and stably converge to the optimal weighting in simulated and real cardiovascular data. Signal quality is restored with minimal distortion, increasing the accuracy of biophysical measurement.

  19. Adaptive Activation of a Stress Response Pathway Improves Learning and Memory Through Gs and β-Arrestin-1-Regulated Lactate Metabolism.

    Science.gov (United States)

    Dong, Jun-Hong; Wang, Yi-Jing; Cui, Min; Wang, Xiao-Jing; Zheng, Wen-Shuai; Ma, Ming-Liang; Yang, Fan; He, Dong-Fang; Hu, Qiao-Xia; Zhang, Dao-Lai; Ning, Shang-Lei; Liu, Chun-Hua; Wang, Chuan; Wang, Yue; Li, Xiang-Yao; Yi, Fan; Lin, Amy; Kahsai, Alem W; Cahill, Thomas Joseph; Chen, Zhe-Yu; Yu, Xiao; Sun, Jin-Peng

    2017-04-15

    Stress is a conserved physiological response in mammals. Whereas moderate stress strengthens memory to improve reactions to previously experienced difficult situations, too much stress is harmful. We used specific β-adrenergic agonists, as well as β 2 -adrenergic receptor (β2AR) and arrestin knockout models, to study the effects of adaptive β2AR activation on cognitive function using Morris water maze and object recognition experiments. We used molecular and cell biological approaches to elucidate the signaling subnetworks. We observed that the duration of the adaptive β2AR activation determines its consequences on learning and memory. Short-term formoterol treatment, for 3 to 5 days, improved cognitive function; however, prolonged β2AR activation, for more than 6 days, produced harmful effects. We identified the activation of several signaling networks downstream of β2AR, as well as an essential role for arrestin and lactate metabolism in promoting cognitive ability. Whereas Gs-protein kinase A-cyclic adenosine monophosphate response element binding protein signaling modulated monocarboxylate transporter 1 expression, β-arrestin-1 controlled expression levels of monocarboxylate transporter 4 and lactate dehydrogenase A through the formation of a β-arrestin-1/phospho-mitogen-activated protein kinase/hypoxia-inducible factor-1α ternary complex to upregulate lactate metabolism in astrocyte-derived U251 cells. Conversely, long-term treatment with formoterol led to the desensitization of β2ARs, which was responsible for its decreased beneficial effects. Our results not only revealed that β-arrestin-1 regulated lactate metabolism to contribute to β2AR functions in improved memory formation, but also indicated that the appropriate management of one specific stress pathway, such as through the clinical drug formoterol, may exert beneficial effects on cognitive abilities. Copyright © 2016 Society of Biological Psychiatry. All rights reserved.

  20. Visuo-motor learning with combination of different rates of motor imagery and physical practice.

    Science.gov (United States)

    Allami, Nadia; Paulignan, Yves; Brovelli, Andrea; Boussaoud, Driss

    2008-01-01

    Sports psychology suggests that mental rehearsal facilitates physical practice in athletes and clinical rehabilitation attempts to use mental rehearsal to restore motor function in hemiplegic patients. Our aim was to examine whether mental rehearsal is equivalent to physical learning, and to determine the optimal proportions of real execution and rehearsal. Subjects were asked to grasp an object and insert it into an adapted slot. One group (G0) practiced the task only by physical execution (240 trials); three groups imagined performing the task in different rates of trials (25%, G25; 50%, G50; 75%, G75), and physically executed movements for the remaining trials; a fourth, control group imagined a visual rotation task in 75% of the trials and then performed the same motor task as the others groups. Movement time (MT) was compared for the first and last physical trials, together with other key trials, across groups. All groups learned, suggesting that mental rehearsal is equivalent to physical motor learning. More importantly, when subjects rehearsed the task for large numbers of trials (G50 and G75), the MT of the first executed trial was significantly shorter than the first executed trial in the physical group (G0), indicating that mental practice is better than no practice at all. Comparison of the first executed trial in G25, G50 and G75 with the corresponding trials in G0 (61, 121 and 181 trials), showed equivalence between mental and physical practice. At the end of training, the performance was much better with high rates of mental practice (G50/G75) compared to physical practice alone (G0), especially when the task was difficult. These findings confirm that mental rehearsal can be beneficial for motor learning and suggest that imagery might be used to supplement or partly replace physical practice in clinical rehabilitation.

  1. Short-term heat acclimation training improves physical performance: a systematic review, and exploration of physiological adaptations and application for team sports.

    Science.gov (United States)

    Chalmers, Samuel; Esterman, Adrian; Eston, Roger; Bowering, K Jane; Norton, Kevin

    2014-07-01

    Studies have demonstrated that longer-term heat acclimation training (≥8 heat exposures) improves physical performance. The physiological adaptations gained through short-term heat acclimation (STHA) training suggest that physical performance can be enhanced within a brief timeframe. The aim of this systematic review was to determine if STHA training (≤7 heat exposures) can improve physical performance in healthy adults. MEDLINE, PubMed, and SPORTDiscus™ databases were searched for available literature. Studies were included if they met the following criteria: STHA intervention, performance measure outcome, apparently healthy participants, adult participants (≥18 years of age), primary data, and human participants. A modified McMaster critical appraisal tool determined the level of bias in each included study. Eight papers met the inclusion criteria. Studies varied from having a low to a high risk of bias. The review identified aerobic-based tests of performance benefit from STHA training. Peak anaerobic power efforts have not been demonstrated to improve. At the review level, this systematic review did not include tolerance time exercise tests; however, certain professions may be interested in this type of exercise (e.g. fire-fighters). At the outcome level, the review was limited by the moderate level of bias that exists in the field. Only two randomized controlled trials were included. Furthermore, a limited number of studies could be identified (eight), and only one of these articles focused on women participants. The review identified that aerobic-based tests of performance benefit from STHA training. This is possibly through a number of cardiovascular, thermoregulatory, and metabolic adaptations improving the perception of effort and fatigue through a reduction in anaerobic energy release and elevation of the anaerobic threshold. These results should be viewed with caution due to the level of available evidence, and the limited number of papers that

  2. Modified compensation algorithm of lever-arm effect and flexural deformation for polar shipborne transfer alignment based on improved adaptive Kalman filter

    Science.gov (United States)

    Wang, Tongda; Cheng, Jianhua; Guan, Dongxue; Kang, Yingyao; Zhang, Wei

    2017-09-01

    Due to the lever-arm effect and flexural deformation in the practical application of transfer alignment (TA), the TA performance is decreased. The existing polar TA algorithm only compensates a fixed lever-arm without considering the dynamic lever-arm caused by flexural deformation; traditional non-polar TA algorithms also have some limitations. Thus, the performance of existing compensation algorithms is unsatisfactory. In this paper, a modified compensation algorithm of the lever-arm effect and flexural deformation is proposed to promote the accuracy and speed of the polar TA. On the basis of a dynamic lever-arm model and a noise compensation method for flexural deformation, polar TA equations are derived in grid frames. Based on the velocity-plus-attitude matching method, the filter models of polar TA are designed. An adaptive Kalman filter (AKF) is improved to promote the robustness and accuracy of the system, and then applied to the estimation of the misalignment angles. Simulation and experiment results have demonstrated that the modified compensation algorithm based on the improved AKF for polar TA can effectively compensate the lever-arm effect and flexural deformation, and then improve the accuracy and speed of TA in the polar region.

  3. Improved Transient Performance of a Fuzzy Modified Model Reference Adaptive Controller for an Interacting Coupled Tank System Using Real-Coded Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Asan Mohideen Khansadurai

    2014-01-01

    Full Text Available The main objective of the paper is to design a model reference adaptive controller (MRAC with improved transient performance. A modification to the standard direct MRAC called fuzzy modified MRAC (FMRAC is used in the paper. The FMRAC uses a proportional control based Mamdani-type fuzzy logic controller (MFLC to improve the transient performance of a direct MRAC. The paper proposes the application of real-coded genetic algorithm (RGA to tune the membership function parameters of the proposed FMRAC offline so that the transient performance of the FMRAC is improved further. In this study, a GA based modified MRAC (GAMMRAC, an FMRAC, and a GA based FMRAC (GAFMRAC are designed for a coupled tank setup in a hybrid tank process and their transient performances are compared. The results show that the proposed GAFMRAC gives a better transient performance than the GAMMRAC or the FMRAC. It is concluded that the proposed controller can be used to obtain very good transient performance for the control of nonlinear processes.

  4. Improving Interactions between a Power-Assist Robot System and Its Human User in Horizontal Transfer of Objects Using a Novel Adaptive Control Method

    Directory of Open Access Journals (Sweden)

    S. M. Mizanoor Rahman

    2012-01-01

    Full Text Available Power assist systems are usually used for rehabilitation, healthcare, and so forth.This paper puts emphasis on the use of power assist systems for object transfer and thus brings a novelty in the power-assist applications. However, the interactions between the systems and the human users are usually not satisfactory because human features are not included in the control design. In this paper, we present the development of a 1-DOF power assist system for horizontal transfer of objects. We included human features such as weight perception in the system dynamics and control. We then simulated the system using MATLAB/Simulink for transferring objects with it and (i determined the optimum maneuverability conditions for object transfer, (ii determined psychophysical relationships between actual and perceived weights, and (iii analyzed load forces and motion features. We then used the findings to design a novel adaptive control scheme to improve the interactions between the user and the system. We implemented the novel control (simulated the system again using the novel control, the subjects evaluated the system, and the results showed that the novel control reduced the excessive load forces and accelerations and thus improved the human-system interactions in terms of maneuverability, safety, and so forth. Finally, we proposed to use the findings to develop power assist systems for manipulating heavy objects in industries that may improve interactions between the systems and the users.

  5. Using blue-green light at night and blue-blockers during the day to improves adaptation to night work: a pilot study.

    Science.gov (United States)

    Sasseville, Alexandre; Hébert, Marc

    2010-10-01

    Bright light at night paired with darkness during the day seem to facilitate adaptation to night work. Considering the biological clock sensitive to short wavelengths, we investigated the possibility of adaptation in shift workers exposed to blue-green light at night, combined with using blue-blockers during the day. Four sawmill shift workers were evaluated during two weeks of night shifts (control and experimental) and one week of day shifts. Throughout the experimental week, ambient light (approximately 130 lx) was supplemented with blue-green light (200 lx) from 00:00 h to: 05:00 h on Monday and Tuesday, 06:00 h on Wednesday and 07:00 h on Thursday. Blue-blockers had to be worn outside from the end of the night shift until 16:00 h. For circadian assessment, salivary melatonin profiles were obtained between 00:00 h and 08:00 h, before and after 4 experimental night shifts. Sleep was continuously monitored with actigraphy and subjective vigilance was measured at the beginning, the middle and the end of each night and day shifts. The error percentage in wood board classification was used as an index of performance. Through experimental week, melatonin profiles of 3 participants have shifted by at least 2 hours. Improvements were observed in sleep parameters and subjective vigilance from the third night (Wednesday) as performance increased on the fourth night (Thursday) from 5.14% to 1.36% of errors (p=0.04). Strategic exposure to short wavelengths at night, and/or daytime use of blue-blocker glasses, seemed to improve sleep, vigilance and performance. Copyright © 2010 Elsevier Inc. All rights reserved.

  6. Developing a new case based computer-aided detection scheme and an adaptive cueing method to improve performance in detecting mammographic lesions

    Science.gov (United States)

    Tan, Maxine; Aghaei, Faranak; Wang, Yunzhi; Zheng, Bin

    2017-01-01

    The purpose of this study is to evaluate a new method to improve performance of computer-aided detection (CAD) schemes of screening mammograms with two approaches. In the first approach, we developed a new case based CAD scheme using a set of optimally selected global mammographic density, texture, spiculation, and structural similarity features computed from all four full-field digital mammography images of the craniocaudal (CC) and mediolateral oblique (MLO) views by using a modified fast and accurate sequential floating forward selection feature selection algorithm. Selected features were then applied to a ‘scoring fusion’ artificial neural network classification scheme to produce a final case based risk score. In the second approach, we combined the case based risk score with the conventional lesion based scores of a conventional lesion based CAD scheme using a new adaptive cueing method that is integrated with the case based risk scores. We evaluated our methods using a ten-fold cross-validation scheme on 924 cases (476 cancer and 448 recalled or negative), whereby each case had all four images from the CC and MLO views. The area under the receiver operating characteristic curve was AUC  =  0.793  ±  0.015 and the odds ratio monotonically increased from 1 to 37.21 as CAD-generated case based detection scores increased. Using the new adaptive cueing method, the region based and case based sensitivities of the conventional CAD scheme at a false positive rate of 0.71 per image increased by 2.4% and 0.8%, respectively. The study demonstrated that supplementary information can be derived by computing global mammographic density image features to improve CAD-cueing performance on the suspicious mammographic lesions.

  7. Improvement in ethanol productivity of engineered E. coli strain SSY13 in defined medium via adaptive evolution.

    Science.gov (United States)

    Jilani, Syed Bilal; Venigalla, Siva Sai Krishna; Mattam, Anu Jose; Dev, Chandra; Yazdani, Syed Shams

    2017-09-01

    E. coli has the ability to ferment both C5 and C6 sugars and produce mixture of acids along with small amount of ethanol. In our previous study, we reported the construction of an ethanologenic E. coli strain by modulating flux through the endogenous pathways. In the current study, we made further changes in the strain to make the overall process industry friendly; the changes being (1) removal of plasmid, (2) use of low-cost defined medium, and (3) improvement in consumption rate of both C5 and C6 sugars. We first constructed a plasmid-free strain SSY13 and passaged it on AM1-xylose minimal medium plate for 150 days. Further passaging was done for 56 days in liquid AM1 medium containing either glucose or xylose on alternate days. We observed an increase in specific growth rate and carbon utilization rate with increase in passage numbers until 42 days for both glucose and xylose. The 42nd day passaged strain SSK42 fermented 113 g/L xylose in AM1 minimal medium and produced 51.1 g/L ethanol in 72 h at 89% of maximum theoretical yield with ethanol productivity of 1.4 g/L/h during 24-48 h of fermentation. The ethanol titer, yield and productivity were 49, 40 and 36% higher, respectively, for SSK42 as compared to unevolved SSY13 strain.

  8. Food Legumes and Rising Temperatures: Effects, Adaptive Functional Mechanisms Specific to Reproductive Growth Stage and Strategies to Improve Heat Tolerance

    Directory of Open Access Journals (Sweden)

    Kumari Sita

    2017-10-01

    Full Text Available Ambient temperatures are predicted to rise in the future owing to several reasons associated with global climate changes. These temperature increases can result in heat stress- a severe threat to crop production in most countries. Legumes are well-known for their impact on agricultural sustainability as well as their nutritional and health benefits. Heat stress imposes challenges for legume crops and has deleterious effects on the morphology, physiology, and reproductive growth of plants. High-temperature stress at the time of the reproductive stage is becoming a severe limitation for production of grain legumes as their cultivation expands to warmer environments and temperature variability increases due to climate change. The reproductive period is vital in the life cycle of all plants and is susceptible to high-temperature stress as various metabolic processes are adversely impacted during this phase, which reduces crop yield. Food legumes exposed to high-temperature stress during reproduction show flower abortion, pollen and ovule infertility, impaired fertilization, and reduced seed filling, leading to smaller seeds and poor yields. Through various breeding techniques, heat tolerance in major legumes can be enhanced to improve performance in the field. Omics approaches unravel different mechanisms underlying thermotolerance, which is imperative to understand the processes of molecular responses toward high-temperature stress.

  9. Culturally adaptive storytelling intervention versus didactic intervention to improve hypertension control in Vietnam: a cluster-randomized controlled feasibility trial.

    Science.gov (United States)

    Nguyen, Hoa L; Allison, Jeroan J; Ha, Duc A; Chiriboga, Germán; Ly, Ha N; Tran, Hanh T; Nguyen, Cuong K; Dang, Diem M; Phan, Ngoc T; Vu, Nguyen C; Nguyen, Quang P; Goldberg, Robert J

    2017-01-01

    Vietnam is experiencing an epidemiologic transition with an increased prevalence of non-communicable diseases. Novel, large-scale, effective, and sustainable interventions to control hypertension in Vietnam are needed. We report the results of a cluster-randomized feasibility trial at 3 months follow-up conducted in Hung Yen province, Vietnam, designed to evaluate the feasibility and acceptability of two community-based interventions to improve hypertension control: a "storytelling" intervention, "We Talk about Our Hypertension," and a didactic intervention. The storytelling intervention included stories about strategies for coping with hypertension, with patients speaking in their own words, and didactic content about the importance of healthy lifestyle behaviors including salt reduction and exercise. The didactic intervention included only didactic content. The storytelling intervention was delivered by two DVDs at 3-month intervals; the didactic intervention included only one installment. The trial was conducted in four communes, equally randomized to the two interventions. The mean age of the 160 study patients was 66 years, and 54% were men. Most participants described both interventions as understandable, informative, and motivational. Between baseline and 3 months, mean systolic blood pressure declined by 8.2 mmHg (95% CI 4.1-12.2) in the storytelling group and by 5.5 mmHg (95% CI 1.4-9.5) in the didactic group. The storytelling group also reported a significant increase in hypertension medication adherence. Both interventions were well accepted in several rural communities and were shown to be potentially effective in lowering blood pressure. A large-scale randomized trial is needed to compare the effectiveness of the two interventions in controlling hypertension. ClinicalTrials.gov, NCT02483780.

  10. Stay-green traits to improve wheat adaptation in well-watered and water-limited environments.

    Science.gov (United States)

    Christopher, John T; Christopher, Mandy J; Borrell, Andrew K; Fletcher, Susan; Chenu, Karine

    2016-09-01

    A stay-green phenotype enables crops to retain green leaves longer after anthesis compared with senescent types, potentially improving yield. Measuring the normalized difference vegetative index (NDVI) during the whole senescence period allows quantification of component stay-green traits contributing to a stay-green phenotype. These objective and standardized traits can be compared across genotypes and environments. Traits examined include maximum NDVI near anthesis (Nmax), senescence rate (SR), a trait integrating senescence (SGint), plus time from anthesis to onset (OnS), mid-point (MidS), and near completion (EndS) of senescence. The correlation between stay-green traits and yield was studied in eight contrasting environments ranging from well watered to severely water limited. Environments were each classified into one of the four major drought environment types (ETs) previously identified for the Australian wheat cropping system. SGint, OnS, and MidS tended to have higher values in higher yielding environments for a given genotype, as well as for higher yielding genotypes within a given environment. Correlation between specific stay-green traits and yield varied with ET. In the studied population, SGint, OnS, and MidS strongly correlated with yield in three of the four ETs which included well-watered environments (0.43-0.86), but less so in environments with only moderate water-stress after anthesis (-0.03 to 0.31). In contrast, Nmax was most highly correlated with yield under moderate post-anthesis water stress (0.31-0.43). Selection for particular stay-green traits, combinations of traits, and/or molecular markers associated with the traits could enhance genetic progress toward stay-green wheats with higher, more stable yield in both well-watered and water-limited conditions. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  11. Keeping an Eye on the Conductor: Neural Correlates of Visuo-motor Synchronization and Musical Experience

    Directory of Open Access Journals (Sweden)

    Kentaro eOno

    2015-04-01

    Full Text Available For orchestra musicians, synchronized playing under a conductor’s direction is necessary to achieve optimal performance. Previous studies using simple auditory/visual stimuli have reported cortico-subcortical networks underlying synchronization and that training improves the accuracy of synchronization. However, it is unclear whether people who played regularly under a conductor and non-musicians activate the same networks when synchronizing with a conductor’s gestures. We conducted a functional magnetic resonance imaging (fMRI experiment testing nonmusicians and musicians who regularly play music under a conductor. Participants were required to tap the rhythm they perceived from silent movies displaying either conductor’s gestures or a swinging metronome. Musicians performed tapping under a conductor with more precision than nonmusicians. Results from fMRI measurement showed greater activity in the anterior part of the left superior frontal gyrus (SFG in musicians with more frequent practice under a conductor. Conversely, tapping with the metronome did not show any difference between musicians and nonmusicians, indicating that the expertise effect in tapping under the conductor does not result in a general increase in tapping performance for musicians. These results suggest that orchestra musicians have developed an advanced ability to predict conductor’s next action from the gestures.

  12. Correlation of deglutition in subacute ischemic stroke patients with peripheral blood adaptive immunity: Essential amino acid improvement.

    Science.gov (United States)

    Aquilani, Roberto; Emilio, Benevolo; Dossena, Maurizia; Baiardi, Paola; Testa, Amidio; Boschi, Federica; Viglio, Simona; Iadarola, Paolo; Pasini, Evasio; Verri, Manuela

    2015-12-01

    associated with improved neuro-function tests with evidence that this association is enhanced by supplementing EAAs. © The Author(s) 2015.

  13. Feasibility and Preliminary Efficacy of Visual Cue Training to Improve Adaptability of Walking after Stroke: Multi-Centre, Single-Blind Randomised Control Pilot Trial.

    Directory of Open Access Journals (Sweden)

    Kristen L Hollands

    Full Text Available Given the importance of vision in the control of walking and evidence indicating varied practice of walking improves mobility outcomes, this study sought to examine the feasibility and preliminary efficacy of varied walking practice in response to visual cues, for the rehabilitation of walking following stroke.This 3 arm parallel, multi-centre, assessor blind, randomised control trial was conducted within outpatient neurorehabilitation services.Community dwelling stroke survivors with walking speed <0.8m/s, lower limb paresis and no severe visual impairments.Over-ground visual cue training (O-VCT, Treadmill based visual cue training (T-VCT, and Usual care (UC delivered by physiotherapists twice weekly for 8 weeks.Participants were randomised using computer generated random permutated balanced blocks of randomly varying size. Recruitment, retention, adherence, adverse events and mobility and balance were measured before randomisation, post-intervention and at four weeks follow-up.Fifty-six participants participated (18 T-VCT, 19 O-VCT, 19 UC. Thirty-four completed treatment and follow-up assessments. Of the participants that completed, adherence was good with 16 treatments provided over (median of 8.4, 7.5 and 9 weeks for T-VCT, O-VCT and UC respectively. No adverse events were reported. Post-treatment improvements in walking speed, symmetry, balance and functional mobility were seen in all treatment arms.Outpatient based treadmill and over-ground walking adaptability practice using visual cues are feasible and may improve mobility and balance. Future studies should continue a carefully phased approach using identified methods to improve retention.Clinicaltrials.gov NCT01600391.

  14. The optimal monochromatic spectral computed tomographic imaging plus adaptive statistical iterative reconstruction algorithm can improve the superior mesenteric vessel image quality.

    Science.gov (United States)

    Yin, Xiao-Ping; Zuo, Zi-Wei; Xu, Ying-Jin; Wang, Jia-Ning; Liu, Huai-Jun; Liang, Guang-Lu; Gao, Bu-Lang

    2017-04-01

    To investigate the effect of the optimal monochromatic spectral computed tomography (CT) plus adaptive statistical iterative reconstruction on the improvement of the image quality of the superior mesenteric artery and vein. The gemstone spectral CT angiographic data of 25 patients were reconstructed in the following three groups: 70KeV, the optimal monochromatic imaging, and the optimal monochromatic plus 40%iterative reconstruction mode. The CT value, image noises (IN), background CT value and noises, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR) and image scores of the vessels and surrounding tissues were analyzed. In the 70KeV, the optimal monochromatic and the optimal monochromatic images plus 40% iterative reconstruction group, the mean scores of image quality were 3.86, 4.24 and 4.25 for the superior mesenteric artery and 3.46, 3.78 and 3.81 for the superior mesenteric vein, respectively. The image quality scores for the optimal monochromatic and the optimal monochromatic plus 40% iterative reconstruction groups were significantly greater than for the 70KeV group (Piterative reconstruction group than in the 70KeV group. The optimal monochromatic plus 40% iterative reconstruction group had significantly (Piterative reconstruction using low-contrast agent dosage and low injection rate can significantly improve the image quality of the superior mesenteric artery and vein. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Expression of the citrus CsTIP2;1 gene improves tobacco plant growth, antioxidant capacity and physiological adaptation under stress conditions.

    Science.gov (United States)

    Martins, Cristina P S; Neves, Diana M; Cidade, Luciana C; Mendes, Amanda F S; Silva, Delmira C; Almeida, Alex-Alan F; Coelho-Filho, Mauricio A; Gesteira, Abelmon S; Soares-Filho, Walter S; Costa, Marcio G C

    2017-05-01

    Overexpression of the citrus CsTIP2;1 improves plant growth and tolerance to salt and drought stresses by enhancing cell expansion, H 2 O 2 detoxification and stomatal conductance. Tonoplast intrinsic proteins (TIPs) are a subfamily of aquaporins, belonging to the major intrinsic protein family. In a previous study, we have shown that a citrus TIP isoform, CsTIP2;1, is highly expressed in leaves and also transcriptionally regulated in leaves and roots by salt and drought stresses and infection by 'Candidatus Liberibacter asiaticus', the causal agent of the Huanglongbing disease, suggesting its involvement in the regulation of the flow of water and nutrients required during both normal growth and stress conditions. Here, we show that the overexpression of CsTIP2;1 in transgenic tobacco increases plant growth under optimal and water- and salt-stress conditions and also significantly improves the leaf water and oxidative status, photosynthetic capacity, transpiration rate and water use efficiency of plants subjected to a progressive soil drying. These results correlated with the enhanced mesophyll cell expansion, midrib aquiferous parenchyma abundance, H2O2 detoxification and stomatal conductance observed in the transgenic plants. Taken together, our results indicate that CsTIP2;1 plays an active role in regulating the water and oxidative status required for plant growth and adaptation to stressful environmental conditions and may be potentially useful for engineering stress tolerance in citrus and other crop plants.

  16. Adaptive evolution of the lager brewing yeast Saccharomyces pastorianus for improved growth under hyperosmotic conditions and its influence on fermentation performance.

    Science.gov (United States)

    Ekberg, Jukka; Rautio, Jari; Mattinen, Laura; Vidgren, Virve; Londesborough, John; Gibson, Brian R

    2013-05-01

    An adaptive evolution method to obtain stable Saccharomyces pastorianus brewing yeast variants with improved fermentation capacity is described. The procedure involved selection for rapid growth resumption at high osmotic strength. It was applied to a lager strain and to a previously isolated ethanol-tolerant strain. Fermentation performance of strains was compared at 15 °P wort strength. A selected osmotolerant variant of the ethanol-tolerant strain showed significantly shorter fermentation time than the parent strain, producing 6.45% alcohol by volume beer in 4-5 days with mostly similar organoleptic properties to the original strain. Diacetyl and pentanedione contents were 50-75% and 3-methylbutyl acetate and 2-phenylethyl acetate 50% higher than with the original strain, leading to a small flavour change. The variant contained significantly less intracellular trehalose and glycogen than the parent. Transcriptional analysis of selected genes at 24 h revealed reduced transcription of hexose transport genes and increased transcription of the MALx1 and MALx2 genes, responsible for α-glucoside uptake and metabolism. It is suggested that an attenuated stress response contributes to the improved fermentation performance. Results show that sequential selection for both ethanol tolerance and rapid growth at high osmotic strength can provide strains with enhanced fermentation speed with acceptable product quality. © 2013 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

  17. Leveraging open-source technology and adapting open eLearning content to improve the knowledge and motivation of Ghana’s rural nurses

    Directory of Open Access Journals (Sweden)

    Lisa Mwaikambo

    2016-03-01

    Full Text Available Access to training opportunities is strongly correlated with health workers’ motivation because it enables health workers to take on more challenging duties. Mobile technology can be leveraged for professional development support by providing access to open education resources. Community Health Nurses (CHNs in Ghana are the frontline health workers of the Ghana Health Service (GHS and play a vital role in extending maternal and child health care to rural communities. However, as the lowest credentialed nurses, they are at the bottom of the GHS hierarchy. CHNs have limited opportunities for career advancement and report challenges with isolation and lack of resources. Leveraging open-source technology platforms and open eLearning content, the Care Community Hub (CCH project sought to address these barriers in CHN motivation by developing and deploying a mobile application (app, CHN on the Go, to CHNs in five rural districts. The app supports CHNs through tools for continuous learning, diagnostic decision-making, and improved nurse-supervisor interactions. This paper focuses on the adaptation and use of the open eLearning content to address CHNs’ motivation challenges and, ultimately, improve their knowledge and job performance as a result of having access to open education resources.

  18. Adapting the Trials of Improved Practices (TIPs) approach to explore the acceptability and feasibility of nutrition and parenting recommendations: what works for low-income families?

    Science.gov (United States)

    Dickin, Katherine L; Seim, Gretchen

    2015-10-01

    Interventions to prevent childhood obesity must consider not only how child feeding behaviours are related to child weight status but also which behaviours parents are willing and able to change. This study adapted Trials of Improved Practices (TIPs) to assess acceptability and feasibility of nutrition and parenting recommendations, using in-depth interviews and household trials to explore families' experiences over time. A diverse sample of 23 low-income parents of 3-11-year-olds was recruited following participation in nutrition and parenting education. Parents chose nutrition and parenting practices to try at home and were interviewed 2 weeks and 4-6 months later about behaviour change efforts. Qualitative analysis identified emergent themes, and acceptability and feasibility were rated based on parents' willingness and ability to try new practices. The nutrition goal parents chose most frequently was increasing children's vegetable intake, followed by replacing sweetened beverages with water or milk, and limiting energy-dense foods. Parents were less inclined to reduce serving sizes. The parenting practices most often selected as applicable to nutrition goals were role-modelling; shaping home environments, often with other adults; involving children in decisions; and providing positive feedback. Most recommendations were viewed as acceptable by meaningful numbers of parents, many of whom tried and sustained new behaviours. Food preferences, habits and time were common barriers; family resistance or food costs also constrained some parents. Despite challenges, TIPs was successfully adapted to evaluate complex nutrition and parenting practices. Information on parents' willingness and ability to try practices provides valuable guidance for childhood obesity prevention programmes. © 2013 John Wiley & Sons Ltd.

  19. Image guided adaptive brachytherapy with combined intracavitary and interstitial technique improves the therapeutic ratio in locally advanced cervical cancer: Analysis from the retroEMBRACE study.

    Science.gov (United States)

    Fokdal, Lars; Sturdza, Alina; Mazeron, Renaud; Haie-Meder, Christine; Tan, Li Tee; Gillham, Charles; Šegedin, Barbara; Jürgenliemk-Schultz, Ina; Kirisits, Christian; Hoskin, Peter; Pötter, Richard; Lindegaard, Jacob C; Tanderup, Kari

    2016-09-01

    Image guided adaptive brachytherapy (IGABT) using intracavitary applicators (IC) has led to a significant improvement of local control in locally advanced cervical cancer (LACC). Further improvement has been obtained with combined intracavitary/interstitial (IC/IS) applicators. The aim of this analysis was to evaluate the impact on local control and late morbidity of application of combined IS/IC brachytherapy in a large multicentre population. 610 patients with LACC from the retroEMBRACE study were included. Patients were divided into an IC group (N=310) and an IC/IS group (N=300). The IC/IS group was defined from the time point, when a centre performed IC/IS brachytherapy in more than 20% of cases. With systematic usage of IC/IS the D90 of CTV HR increased from 83±14Gy to 92±13Gy (p<0.01). No difference in doses to organs at risk was found. The 3-year local control rate in patients having a CTV HR volume⩾30cm 3 was 10% higher (p=0.02) in the IC/IS group. No difference was found for CTV HR <30cm 3 (p=0.50). No significant difference in late morbidity was found between the IC/IS group and IC group. Combined IC/IS brachytherapy improves the therapeutic ratio in LACC by enabling a tumour specific dose escalation resulting in significantly higher local control in large tumours without adding treatment related late morbidity. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  20. Impairment in explicit visuomotor sequence learning is related to loss of microstructural integrity of the corpus callosum in multiple sclerosis patients with minimal disability.

    Science.gov (United States)

    Bonzano, L; Tacchino, A; Roccatagliata, L; Sormani, M P; Mancardi, G L; Bove, M

    2011-07-15

    Sequence learning can be investigated by serial reaction-time (SRT) paradigms. Explicit learning occurs when subjects have to recognize a test sequence and has been shown to activate the frontoparietal network in both contralateral and ipsilateral hemispheres. Thus, the left and right superior longitudinal fasciculi (SLF), connecting the intra-hemispheric frontoparietal circuits, could have a role in explicit unimanual visuomotor learning. Also, as both hemispheres are involved, we could hypothesize that the corpus callosum (CC) has a role in this process. Pathological damage in both SLF and CC has been detected in patients with Multiple Sclerosis (PwMS), and microstructural alterations can be quantified by Diffusion Tensor Imaging (DTI). In light of these findings, we inquired whether PwMS with minimal disability showed impairments in explicit visuomotor sequence learning and whether this could be due to loss of white matter integrity in these intra- and inter-hemispheric white matter pathways. Thus, we combined DTI analysis with a modified version of SRT task based on finger opposition movements in a group of PwMS with minimal disability. We found that the performance in explicit sequence learning was significantly reduced in these patients with respect to healthy subjects; the amount of sequence-specific learning was found to be more strongly correlated with fractional anisotropy (FA) in the CC (r=0.93) than in the left (r=0.28) and right SLF (r=0.27) (p for interaction=0.005 and 0.04 respectively). This finding suggests that an inter-hemispheric information exchange between the homologous areas is required to successfully accomplish the task and indirectly supports the role of the right (ipsilateral) hemisphere in explicit visuomotor learning. On the other hand, we found no significant correlation of the FA in the CC and in the SLFs with nonspecific learning (assessed when stimuli are randomly presented), supporting the hypothesis that inter

  1. Adaptive Crowdsourcing and Improved Innovation

    DEFF Research Database (Denmark)

    Edgeman, Rick; Engell, Toke; Jensen, Nik Grewy

    Crowdsourcing is central to enterprise open innovation efforts, providing a source of labor, funding, and ideas. Though use of crowdsourcing in selected environments is well understood, application in business-to-business (B2B) market environments has been limited. Selected reasons for this...

  2. Context-Dependent Arm Pointing Adaptation

    Science.gov (United States)

    Seidler, R. D.; Bloomberg, J. J.; Stelmach, G. E.

    2000-01-01

    We sought to determine the effectiveness of head posture as a contextual cue to facilitate adaptive transitions in manual control during visuomotor distortions. Subjects performed arm pointing movements by drawing on a digitizing tablet, with targets and movement trajectories displayed in real time on a computer monitor. Adaptation was induced by presenting the trajectories in an altered gain format on the monitor. The subjects were shown visual displays of their movements that corresponded to either 0.5 or 1.5 scaling of the movements made. Subjects were assigned to three groups: the head orientation group tilted the head towards the right shoulder when drawing under a 0.5 gain of display and towards the left shoulder when drawing under a 1.5 gain of display, the target orientation group had the home & target positions rotated counterclockwise when drawing under the 0.5 gain and clockwise for the 1.5 gain, the arm posture group changed the elbow angle of the arm they were not drawing with from full flexion to full extension with 0.5 and 1.5 gain display changes. To determine if contextual cues were associated with display alternations, the gain changes were returned to the standard (1.0) display. Aftereffects were assessed to determine the efficacy of the head orientation contextual cue. . compared to the two control cues. The head orientation cue was effectively associated with the multiple gains. The target orientation cue also demonstrated some effectiveness while the.arm posture cue did not. The results demonstrate that contextual cues can be used to switch between multiple adaptive states. These data provide support for the idea that static head orientation information is a crucial component to the arm adaptation process. These data further define the functional linkage between head posture and arm pointing movements.

  3. Adaptive management of rangeland systems

    Science.gov (United States)

    Allen, Craig R.; Angeler, David G.; Fontaine, Joseph J.; Garmestani, Ahjond S.; Hart, Noelle M.; Pope, Kevin L.; Twidwell, Dirac

    2017-01-01

    Adaptive management is an approach to natural resource management that uses structured learning to reduce uncertainties for the improvement of management over time. The origins of adaptive management are linked to ideas of resilience theory and complex systems. Rangeland management is particularly well suited for the application of adaptive management, having sufficient controllability and reducible uncertainties. Adaptive management applies the tools of structured decision making and requires monitoring, evaluation, and adjustment of management. Adaptive governance, involving sharing of power and knowledge among relevant stakeholders, is often required to address conflict situations. Natural resource laws and regulations can present a barrier to adaptive management when requirements for legal certainty are met with environmental uncertainty. However, adaptive management is possible, as illustrated by two cases presented in this chapter. Despite challenges and limitations, when applied appropriately adaptive management leads to improved management through structured learning, and rangeland management is an area in which adaptive management shows promise and should be further explored.

  4. Improvement of adaptive fuzzy control for a photovoltaic/wind/diesel generating system; Taiyoko/furyoku/diesel hatsuden system no saitekigata fuzzy seigyo no kairyo

    Energy Technology Data Exchange (ETDEWEB)

    Nagaike, H.; Kenmoku, Y.; Sakakibara, T. [Toyohashi University of Technology, Aichi (Japan); Nakagawa, S. [Maizuru National College of Technology, Kyoto (Japan); Kawamoto, T. [Shizuoka University, Shizuoka (Japan).Faculty of Engineering

    1996-10-27

    The photovoltaic/wind/diesel generating system that uses a storage battery as auxiliary power has been proposed to supply power from the system to the independent area. In this system, it is important to generate no insufficient power from the viewpoint of effective energy utilization and minimize the fuel consumption of a diesel generator. Authors have proposed the adaptive fuzzy control that changes the shape of the membership function of input variables according to the parameter indicating the system state. However, a parameter was rapidly changed in the conventional method. This badly influences the control. Therefore, the way to determine the parameter that indicates the state of this system was improved. Assume that an input value is set to the average value between a certain point of time and the {Delta}t time as the method for determining a parameter. If the {Delta}t value is lower, the change in a membership function is more effective. As a result, a greater fuel reduction effect was obtained. 4 refs., 8 figs., 1 tab.

  5. Meal feeding improves oral glucose tolerance in male rats and causes adaptations in postprandial islet hormone secretion that are independent of plasma incretins or glycemia.

    Science.gov (United States)

    Vahl, Torsten P; Aulinger, Benedikt A; Smith, Eric P; Drazen, Deborah L; Ulrich-Lai, Yve; Seeley, Randy J; Woods, Stephen C; D'Alessio, David A

    2014-11-01

    Meal-fed (MF) rats with access to food for only 4 consecutive hours during the light cycle learn to eat large meals to maintain energy balance. MF animals develop behavioral and endocrine changes that permit glucose tolerance despite increased meal size. We hypothesized that enhanced activity of the enteroinsular axis mediates glucose homeostasis during MF. Cohorts of rats were allocated to MF or ad libitum (AL) regimens for 2-4 wk. Insulin secretion and glucose tolerance were determined after oral carbohydrate and intraperitoneal (ip) and intravenous (iv) glucose. MF rats ate less than AL in the first week but maintained a comparable weight trajectory thereafter. MF rats had decreased glucose excursions after a liquid mixed meal (AUC: MF 75 ± 7, AL 461 ± 28 mmol·l⁻¹·min, P blood glucose. Both groups had comparable fasting glucagon levels, but postprandial responses were lower with MF. However, neither intestinal expression of proGIP and proglucagon mRNA nor plasma incretin levels differed between MF and AL groups. There were no differences in the insulin response to ip or iv glucose between MF and AL rats. These findings demonstrate that MF improves oral glucose tolerance and is associated with significant changes in postprandial islet hormone secretion. Because MF enhanced β-cell function during oral but not parenteral carbohydrate administration, and was not accounted for by changes in circulating incretins, these results support a neural mechanism of adaptive insulin secretion.

  6. Local Stories Adapted as Learning Tools Innovation of Fairy Tale for Teacher to Improve the Literacy Skills of Student in Secondary Schools

    Directory of Open Access Journals (Sweden)

    Nazla Maharani Umaya

    2017-04-01

    Full Text Available One of the obstacles on the fairy tale of learning in secondary schools is there is not enough learning tool as an innovation. The example is found only one or two kind of teaching materials that use for learning, and only about 25% of the fairy tale text has from the local stories in each material. Student need more material than that to help them finish the study easily. The methods of research is exploratory mixed design. It's because the first sequent of this research is gathering qualitative data exploration for development, and collecting qualitative data to explain relationship found in the quantitative data (experimental result. An epic story is an object of the local stories chosen. All developed a tools consisting of a teacher guide, student books, and audiovisual. The result of this research is an increased literacy in students and the effectiveness of learning tools of the fairy tale for secondary school students. The conclusions is the study that the local story adapted as a learning tools innovation is effective to facilitate student learning and improve literacy skills better than regular tools. It can be a part of technical innovation competency development training of teachers in teaching. Except where otherwise noted, content on this site is licensed under a Creative Commons Attribution 4.0 International License

  7. Kinetic analysis of a Saccharomyces cerevisiae strain adapted for improved growth on glycerol: Implications for the development of yeast bioprocesses on glycerol.

    Science.gov (United States)

    Ochoa-Estopier, A; Lesage, J; Gorret, N; Guillouet, S E

    2011-01-01

    Glycerol is an agro-industrial residue generated in high amounts during the biodiesel production. The growing production of biodiesel is creating a worldwide glycerol surplus. Therefore, replacing sugar-based feedstock in bioprocesses by glycerol could be potentially attractive. Saccharomyces cerevisiae is one of the most commonly used microorganisms in the agri-food industry and therefore currently produced in large quantities from sugar-based feedstock. Unfortunately, growth of S. cerevisiae strains on glycerol is very low with reported μmax around 0.01 h(-1). This study demonstrates that successive growth of the S. cerevisiae CBS 8066, CEN.PK 113-7 D and Ethanol Red on glycerol as sole carbon source considerably improved the μmax from 0.01 up to 0.2 h(-1). The "adapted strain" CBS 8066-FL20 was kinetically characterized during aerobic and oxygen-limited cultivation in bioreactor and the results discussed in terms of their implication for developing glycerol-based S. cerevisiae bioprocesses. Copyright © 2010 Elsevier Ltd. All rights reserved.

  8. Quantifying the Adaptive Cycle.

    Directory of Open Access Journals (Sweden)

    David G Angeler

    Full Text Available The adaptive cycle was proposed as a conceptual model to portray patterns of change in complex systems. Despite the model having potential for elucidating change across systems, it has been used mainly as a metaphor, describing system dynamics qualitatively. We use a quantitative approach for testing premises (reorganisation, conservatism, adaptation in the adaptive cycle, using Baltic Sea phytoplankton communities as an example of such complex system dynamics. Phytoplankton organizes in recurring spring and summer blooms, a well-established paradigm in planktology and succession theory, with characteristic temporal trajectories during blooms that may be consistent with adaptive cycle phases. We used long-term (1994-2011 data and multivariate analysis of community structure to assess key components of the adaptive cycle. Specifically, we tested predictions about: reorganisation: spring and summer blooms comprise distinct community states; conservatism: community trajectories during individual adaptive cycles are conservative; and adaptation: phytoplankton species during blooms change in the long term. All predictions were supported by our analyses. Results suggest that traditional ecological paradigms such as phytoplankton successional models have potential for moving the adaptive cycle from a metaphor to a framework that can improve our understanding how complex systems organize and reorganize following collapse. Quantifying reorganization, conservatism and adaptation provides opportunities to cope with the intricacies and uncertainties associated with fast ecological change, driven by shifting system controls. Ultimately, combining traditional ecological paradigms with heuristics of complex system dynamics using quantitative approaches may help refine ecological theory and improve our understanding of the resilience of ecosystems.

  9. Quantifying the adaptive cycle

    Science.gov (United States)

    Angeler, David G.; Allen, Craig R.; Garmestani, Ahjond S.; Gunderson, Lance H.; Hjerne, Olle; Winder, Monika

    2015-01-01

    The adaptive cycle was proposed as a conceptual model to portray patterns of change in complex systems. Despite the model having potential for elucidating change across systems, it has been used mainly as a metaphor, describing system dynamics qualitatively. We use a quantitative approach for testing premises (reorganisation, conservatism, adaptation) in the adaptive cycle, using Baltic Sea phytoplankton communities as an example of such complex system dynamics. Phytoplankton organizes in recurring spring and summer blooms, a well-established paradigm in planktology and succession theory, with characteristic temporal trajectories during blooms that may be consistent with adaptive cycle phases. We used long-term (1994–2011) data and multivariate analysis of community structure to assess key components of the adaptive cycle. Specifically, we tested predictions about: reorganisation: spring and summer blooms comprise distinct community states; conservatism: community trajectories during individual adaptive cycles are conservative; and adaptation: phytoplankton species during blooms change in the long term. All predictions were supported by our analyses. Results suggest that traditional ecological paradigms such as phytoplankton successional models have potential for moving the adaptive cycle from a metaphor to a framework that can improve our understanding how complex systems organize and reorganize following collapse. Quantifying reorganization, conservatism and adaptation provides opportunities to cope with the intricacies and uncertainties associated with fast ecological change, driven by shifting system controls. Ultimately, combining traditional ecological paradigms with heuristics of complex system dynamics using quantitative approaches may help refine ecological theory and improve our understanding of the resilience of ecosystems.

  10. Adaptive management

    DEFF Research Database (Denmark)

    Rist, Lucy; Campbell, Bruce Morgan; Frost, Peter

    2013-01-01

    Adaptive management (AM) emerged in the literature in the mid-1970s in response both to a realization of the extent of uncertainty involved in management, and a frustration with attempts to use modelling to integrate knowledge and make predictions. The term has since become increasingly widely used...... in scientific articles, policy documents and management plans, but both understanding and application of the concept is mixed. This paper reviews recent literature from conservation and natural resource management journals to assess diversity in how the term is used, highlight ambiguities and consider how...... the concept might be further assessed. AM is currently being used to describe many different management contexts, scales and locations. Few authors define the term explicitly or describe how it offers a means to improve management outcomes in their specific management context. Many do not adhere to the idea...

  11. Dissociation of the Reach and the Grasp in the destriate (V1) monkey Helen: a new anatomy for the dual visuomotor channel theory of reaching.

    Science.gov (United States)

    Whishaw, Ian Q; Karl, Jenni M; Humphrey, Nicholas K

    2016-08-01

    Dual visuomotor channel theory proposes that reaching depends on two neural pathways that extend from visual cortex (V1) to motor cortex via the parietal lobe. The Reach pathway directs the hand to the target's location and the Grasp pathway shapes the hand and digits for purchase. Sighted human participants integrate the Reach and the Grasp, but without vision they dissociate the movements to capitalize on tactile cues. They use a Reach with a relatively open hand to locate the target and then they use touch cues to shape the fingers to Grasp. After a V1 lesion, the rhesus monkey, Helen, learned to make near-normal visual discriminations based on size and brightness but displayed visual agnosia. She also learned to reach for food with her mouth and her hands. The present analysis of film of her reaching behavior shows that she dissociated the Reach and the Grasp, as do unsighted human participants reaching for a food target at a fixed location. Her rapid and direct Reach was made with an open hand and extended fingers to contact the food with the palm whereas her Grasp was initiated after she touched the food. She also visually fixated the target during the Reach and visually disengaged after target contact, as do sighted human participants. In contrast, Helen did integrate the Reach and the Grasp to take food from her mouth, demonstrating that she could integrate the movements using online tactile cues. The finding that extrastriate pathways can direct the hand toward extrinsic target properties (location) but not intrinsic target properties (size and shape) is discussed as a novel addition to dual visuomotor channel theory.

  12. Adapted yoga to improve physical function and health-related quality of life in physically-inactive older adults: a randomised controlled pilot trial.

    Science.gov (United States)

    Tew, Garry A; Howsam, Jenny; Hardy, Matthew; Bissell, Laura

    2017-06-23

    Yoga is a holistic therapy of expanding popularity, which has the potential to produce a range of physical, mental and social benefits. This trial evaluated the feasibility and effects of an adapted yoga programme on physical function and health-related quality of life in physically-inactive older adults. In this randomised controlled pilot trial, 52 older adults (90% female; mean age 74.8 years, SD 7.2) were randomised 1:1 to a yoga programme or wait-list control. The yoga group (n = 25) received a physical activity education booklet and were invited to attend ten yoga sessions during a 12-week period. The control group (n = 27) received the education booklet only. Measures of physical function (e.g., Short Physical Performance Battery; SPPB), health status (EQ-5D) and mental well-being (Warwick-Edinburgh Mental Well-being Scale; WEMWBS) were assessed at baseline and 3 months. Feasibility was assessed using course attendance and adverse event data, and participant interviews. Forty-seven participants completed follow-up assessments. Median class attendance was 8 (range 3 to 10). At the 3-month follow-up, the yoga group had a higher SPPB total score compared with the control group (mean difference 0.9, 95% confidence interval [CI] -0.3 to 2.0), a faster time to rise from a chair five times (mean difference - 1.73 s, 95% CI -4.08 to 0.62), and better performance on the chair sit-and-reach lower-limb flexibility test (mean difference 5 cm, 95% CI 0 to 10). The yoga group also had superior health status and mental well-being (vs. control) at 3 months, with mean differences in EQ-5D and WEMWBS scores of 0.12 (95% CI, 0.03 to 0.21) and 6 (95% CI, 1 to 11), respectively. The interviews indicated that participants valued attending the yoga programme, and that they experienced a range of benefits. The adapted yoga programme appeared to be feasible and potentially beneficial in terms of improving mental and social well-being and aspects of physical function in

  13. Risk-adapted treatment of acute promyelocytic leukemia based on all-trans retinoic acid and anthracycline with addition of cytarabine in consolidation therapy for high-risk patients: Further improvements in treatment outcome

    NARCIS (Netherlands)

    M.A. Sanz (Miguel Angel); P. Montesinos (Pau); C. Rayón (Chelo); A. Holowiecka (Aleksandra); J. De La Serna (Javier); G. Milone (Gustavo); E. de Lisa (Elena); S. Brunet (Salut); V. Rybio (Vicente); J.M. Ribera (Josep Maria); C. Rivas (Concha); I. Krsnik (Isabel); J.M. Bergua (Juan Miguel); J.D. González (José David); J. Díaz-Mediavilla (Joaquín); R. Rojas (Rafael); F. Manso (Félix); G.J. Ossenkoppele (Gert); B. Löwenberg (Bob)

    2010-01-01

    textabstractA risk-adapted strategy based on all-trans retinoic acid (ATRA) and anthracycline monochemotherapy (PETHEMALPA99 trial) has demonstrated a high antileukemic efficacy in acute promyelocytic leukemia. We designed a new trial (LPA2005) with the objective of achieving stepwise improvements

  14. A SCORING SYSTEM TO IMPROVE DECISION MAKING AND OUTCOMES IN THE ADAPTATION OF RECENTLY CAPTURED WHITE RHINOCEROSES (CERATOTHERIUM SIMUM) TO CAPTIVITY.

    Science.gov (United States)

    Miller, Michele; Kruger, Milandie; Kruger, Marius; Olea-Popelka, Francisco; Buss, Peter

    2016-04-01

    Ninety-four subadult and adult white rhinoceroses (Ceratotherium simum) were captured between February and October, 2009-11, in Kruger National Park and placed in holding bomas prior to translocation to other locations within South Africa. A simple three-category system was developed based on appetite, fecal consistency/volume, and behavior to assess adaptation to bomas. Individual animal and group daily median scores were used to determine trends and when rhinoceroses had successfully adapted to the boma. Seventeen rhinoceroses did not adapt to boma confinement, and 16 were released (1 mortality). No differences in boma scores were observed between rhinoceroses that adapted and those that did not, until day 8, when the first significant differences were observed (adapted score=13 versus nonadapted score=10). The time to reach a boma score determined as successful adaptation (median 19 d) matched subjective observations, which was approximately 3 wk for most rhinoceroses. Unsuccessful adaptation was indicated by an individual boma score of less than 15, typically during the first 2 wk, or a declining trend in scores within the first 7-14 d. This scoring system can be used for most locations and could also be easily adapted to other areas in which rhinoceroses are held in captivity. This tool also provides important information for assessing welfare in newly captured rhinoceroses.

  15. Improvement of near infrared spectroscopic (NIRS) analysis of caffeine in roasted Arabica coffee by variable selection method of stability competitive adaptive reweighted sampling (SCARS)

    Science.gov (United States)

    Zhang, Xuan; Li, Wei; Yin, Bin; Chen, Weizhong; Kelly, Declan P.; Wang, Xiaoxin; Zheng, Kaiyi; Du, Yiping

    2013-10-01

    Coffee is the most heavily consumed beverage in the world after water, for which quality is a key consideration in commercial trade. Therefore, caffeine content which has a significant effect on the final quality of the coffee products requires to be determined fast and reliably by new analytical techniques. The main purpose of this work was to establish a powerful and practical analytical method based on near infrared spectroscopy (NIRS) and chemometrics for quantitative determination of caffeine content in roasted Arabica coffees. Ground coffee samples within a wide range of roasted levels were analyzed by NIR, meanwhile, in which the caffeine contents were quantitative determined by the most commonly used HPLC-UV method as the reference values. Then calibration models based on chemometric analyses of the NIR spectral data and reference concentrations of coffee samples were developed. Partial least squares (PLS) regression was used to construct the models. Furthermore, diverse spectra pretreatment and variable selection techniques were applied in order to obtain robust and reliable reduced-spectrum regression models. Comparing the respective quality of the different models constructed, the application of second derivative pretreatment and stability competitive adaptive reweighted sampling (SCARS) variable selection provided a notably improved regression model, with root mean square error of cross validation (RMSECV) of 0.375 mg/g and correlation coefficient (R) of 0.918 at PLS factor of 7. An independent test set was used to assess the model, with the root mean square error of prediction (RMSEP) of 0.378 mg/g, mean relative error of 1.976% and mean relative standard deviation (RSD) of 1.707%. Thus, the results provided by the high-quality calibration model revealed the feasibility of NIR spectroscopy for at-line application to predict the caffeine content of unknown roasted coffee samples, thanks to the short analysis time of a few seconds and non

  16. Low-tube-voltage, high-tube-current multidetector abdominal CT: improved image quality and decreased radiation dose with adaptive statistical iterative reconstruction algorithm--initial clinical experience.

    Science.gov (United States)

    Marin, Daniele; Nelson, Rendon C; Schindera, Sebastian T; Richard, Samuel; Youngblood, Richard S; Yoshizumi, Terry T; Samei, Ehsan

    2010-01-01

    To investigate whether an adaptive statistical iterative reconstruction (ASIR) algorithm improves the image quality at low-tube-voltage (80-kVp), high-tube-current (675-mA) multidetector abdominal computed tomography (CT) during the late hepatic arterial phase. This prospective, single-center HIPAA-compliant study was institutional review board approved. Informed patient consent was obtained. Ten patients (six men, four women; mean age, 63 years; age range, 51-77 years) known or suspected to have hypervascular liver tumors underwent dual-energy 64-section multidetector CT. High- and low-tube-voltage CT images were acquired sequentially during the late hepatic arterial phase of contrast enhancement. Standard convolution FBP was used to reconstruct 140-kVp (protocol A) and 80-kVp (protocol B) image sets, and ASIR (protocol C) was used to reconstruct 80-kVp image sets. The mean image noise; contrast-to-noise ratio (CNR) relative to muscle for the aorta, liver, and pancreas; and effective dose with each protocol were assessed. A figure of merit (FOM) was computed to normalize the image noise and CNR for each protocol to effective dose. Repeated-measures analysis of variance with Bonferroni adjustment for multiple comparisons was used to compare differences in mean CNR, image noise, and corresponding FOM among the three protocols. The noise power spectra generated from a custom phantom with each protocol were also compared. When image noise was normalized to effective dose, protocol C, as compared with protocols A (P = .0002) and B (P = .0001), yielded an approximately twofold reduction in noise. When the CNR was normalized to effective dose, protocol C yielded significantly higher CNRs for the aorta, liver, and pancreas than did protocol A (P = .0001 for all comparisons) and a significantly higher CNR for the liver than did protocol B (P = .003). Mean effective doses were 17.5 mSv +/- 0.6 (standard error) with protocol A and 5.1 mSv +/- 0.3 with protocols B and C

  17. Acute exercise improves motor memory

    DEFF Research Database (Denmark)

    Skriver, Kasper Christen; Roig, Marc; Lundbye-Jensen, Jesper

    2014-01-01

    We have recently shown that a single bout of acute cardiovascular exercise improves motor skill learning through an optimization of long-term motor memory. Here we expand this previous finding, to explore potential exercise-related biomarkers and their association with measures of motor memory...... and skill acquisition. Thirty-two healthy young male subjects were randomly allocated into either an exercise or control group. Following either an intense bout of cycling or rest subjects practiced a visuomotor tracking task. Motor skill acquisition was assessed during practice and retention 1 hour, 24...... hours and 7 days after practice. Plasma levels of brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF-1), epinephrine, norepinephrine, dopamine and lactate were analyzed at baseline, immediately after exercise or rest and during motor...

  18. Adaptive Lighting

    DEFF Research Database (Denmark)

    Petersen, Kjell Yngve; Søndergaard, Karin; Kongshaug, Jesper

    2015-01-01

    differently into an architectural body. We also examine what might occur when light is dynamic and able to change colour, intensity and direction, and when it is adaptive and can be brought into interaction with its surroundings. In short, what happens to an architectural space when artificial lighting ceases......Adaptive Lighting Adaptive lighting is based on a partial automation of the possibilities to adjust the colour tone and brightness levels of light in order to adapt to people’s needs and desires. IT support is key to the technical developments that afford adaptive control systems. The possibilities...... offered by adaptive lighting control are created by the ways that the system components, the network and data flow can be coordinated through software so that the dynamic variations are controlled in ways that meaningfully adapt according to people’s situations and design intentions. This book discusses...

  19. Adaptive Architectural Envelope

    DEFF Research Database (Denmark)

    Foged, Isak Worre; Kirkegaard, Poul Henning

    2010-01-01

    . The general scopes of this paper are to develop a new adaptive kinetic architectural structure, particularly a reconfigurable architectural structure which can transform body shape from planar geometries to hyper-surfaces using different control strategies, i.e. a transformation into more than one or two......Recent years have seen an increasing variety of applications of adaptive architectural structures for improvement of structural performance by recognizing changes in their environments and loads, adapting to meet goals, and using past events to improve future performance or maintain serviceability...... different shape alternatives. The adaptive structure is a proposal for a responsive building envelope which is an idea of a first level operational framework for present and future investigations towards performance based responsive architectures through a set of responsive typologies. A mock- up concept...

  20. Adaptation investments and homeownership

    DEFF Research Database (Denmark)

    Hansen, Jørgen Drud; Skak, Morten

    2008-01-01

    This article develops a model where ownership improves efficiency of the housing market as it enhances the utility of housing consumption for some consumers. The model is based on an extended Hotelling-Lancaster utility approach in which the ideal variant of housing is obtainable only by adapting...... the home through a supplementary investment. Ownership offers low costs of adaptation, but has high contract costs compared with renting. Consumers simultaneously decide housing demand and tenure, and because of the different cost structure only consumers with strong preferences for individual adaptation...

  1. Quality of life improves in patients with chronic heart failure and Cheyne-Stokes respiration treated with adaptive servo-ventilation in a nurse-led heart failure clinic.

    Science.gov (United States)

    Olseng, Margareth W; Olsen, Brita F; Hetland, Arild; Fagermoen, May S; Jacobsen, Morten

    2017-05-01

    The aim of this study was to investigate if quality of life improved in chronic heart failure patients with Cheyne-Stokes respiration treated with adaptive servo-ventilation in nurse-led heart failure clinic. Cheyne-Stokes respiration is associated with decreased quality of life in patients with chronic heart failure. Adaptive servo-ventilation is introduced to treat this sleep-disordered breathing. Randomised, controlled design. Fifty-one patients (ranging from 53-84 years), New York Heart Association III-IV and/or left ventricular ejection fraction ≤40% and Cheyne-Stokes respiration were randomised to an intervention group who received adaptive servo-ventilation or a control group. Minnesota Living with Heart Failure Questionnaire was us