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Sample records for gait phase dependency

  1. Measuring Gait Quality in Parkinson’s Disease through Real-Time Gait Phase Recognition

    Ilaria Mileti

    2018-03-01

    Full Text Available Monitoring gait quality in daily activities through wearable sensors has the potential to improve medical assessment in Parkinson’s Disease (PD. In this study, four gait partitioning methods, two based on thresholds and two based on a machine learning approach, considering the four-phase model, were compared. The methods were tested on 26 PD patients, both in OFF and ON levodopa conditions, and 11 healthy subjects, during walking tasks. All subjects were equipped with inertial sensors placed on feet. Force resistive sensors were used to assess reference time sequence of gait phases. Goodness Index (G was evaluated to assess accuracy in gait phases estimation. A novel synthetic index called Gait Phase Quality Index (GPQI was proposed for gait quality assessment. Results revealed optimum performance (G < 0.25 for three tested methods and good performance (0.25 < G < 0.70 for one threshold method. The GPQI resulted significantly higher in PD patients than in healthy subjects, showing a moderate correlation with clinical scales score. Furthermore, in patients with severe gait impairment, GPQI was found higher in OFF than in ON state. Our results unveil the possibility of monitoring gait quality in PD through real-time gait partitioning based on wearable sensors.

  2. The Golden Ratio of Gait Harmony: Repetitive Proportions of Repetitive Gait Phases

    Marco Iosa

    2013-01-01

    Full Text Available In nature, many physical and biological systems have structures showing harmonic properties. Some of them were found related to the irrational number known as the golden ratio that has important symmetric and harmonic properties. In this study, the spatiotemporal gait parameters of 25 healthy subjects were analyzed using a stereophotogrammetric system with 25 retroreflective markers located on their skin. The proportions of gait phases were compared with , the value of which is about 1.6180. The ratio between the entire gait cycle and stance phase resulted in 1.620 ± 0.058, that between stance and the swing phase was 1.629 ± 0.173, and that between swing and the double support phase was 1.684 ± 0.357. All these ratios did not differ significantly from each other (, , repeated measure analysis of variance or from (, resp., t-tests. The repetitive gait phases of physiological walking were found in turn in repetitive proportions with each other, revealing an intrinsic harmonic structure. Harmony could be the key for facilitating the control of repetitive walking. Harmony is a powerful unifying factor between seemingly disparate fields of nature, including human gait.

  3. Gait Phase Recognition for Lower-Limb Exoskeleton with Only Joint Angular Sensors

    Liu, Du-Xin; Wu, Xinyu; Du, Wenbin; Wang, Can; Xu, Tiantian

    2016-01-01

    Gait phase is widely used for gait trajectory generation, gait control and gait evaluation on lower-limb exoskeletons. So far, a variety of methods have been developed to identify the gait phase for lower-limb exoskeletons. Angular sensors on lower-limb exoskeletons are essential for joint closed-loop controlling; however, other types of sensors, such as plantar pressure, attitude or inertial measurement unit, are not indispensable.Therefore, to make full use of existing sensors, we propose a novel gait phase recognition method for lower-limb exoskeletons using only joint angular sensors. The method consists of two procedures. Firstly, the gait deviation distances during walking are calculated and classified by Fisher’s linear discriminant method, and one gait cycle is divided into eight gait phases. The validity of the classification results is also verified based on large gait samples. Secondly, we build a gait phase recognition model based on multilayer perceptron and train it with the phase-labeled gait data. The experimental result of cross-validation shows that the model has a 94.45% average correct rate of set (CRS) and an 87.22% average correct rate of phase (CRP) on the testing set, and it can predict the gait phase accurately. The novel method avoids installing additional sensors on the exoskeleton or human body and simplifies the sensory system of the lower-limb exoskeleton. PMID:27690023

  4. A Wearable Gait Phase Detection System Based on Force Myography Techniques

    Xianta Jiang

    2018-04-01

    Full Text Available (1 Background: Quantitative evaluation of gait parameters can provide useful information for constructing individuals’ gait profile, diagnosing gait abnormalities, and better planning of rehabilitation schemes to restore normal gait pattern. Objective determination of gait phases in a gait cycle is a key requirement in gait analysis applications; (2 Methods: In this study, the feasibility of using a force myography-based technique for a wearable gait phase detection system is explored. In this regard, a force myography band is developed and tested with nine participants walking on a treadmill. The collected force myography data are first examined sample-by-sample and classified into four phases using Linear Discriminant Analysis. The gait phase events are then detected from these classified samples using a set of supervisory rules; (3 Results: The results show that the force myography band can correctly detect more than 99.9% of gait phases with zero insertions and only four deletions over 12,965 gait phase segments. The average temporal error of gait phase detection is 55.2 ms, which translates into 2.1% error with respect to the corresponding labelled stride duration; (4 Conclusions: This proof-of-concept study demonstrates the feasibility of force myography techniques as viable solutions in developing wearable gait phase detection systems.

  5. Gait Phase Recognition for Lower-Limb Exoskeleton with Only Joint Angular Sensors

    Du-Xin Liu

    2016-09-01

    Full Text Available Gait phase is widely used for gait trajectory generation, gait control and gait evaluation on lower-limb exoskeletons. So far, a variety of methods have been developed to identify the gait phase for lower-limb exoskeletons. Angular sensors on lower-limb exoskeletons are essential for joint closed-loop controlling; however, other types of sensors, such as plantar pressure, attitude or inertial measurement unit, are not indispensable.Therefore, to make full use of existing sensors, we propose a novel gait phase recognition method for lower-limb exoskeletons using only joint angular sensors. The method consists of two procedures. Firstly, the gait deviation distances during walking are calculated and classified by Fisher’s linear discriminant method, and one gait cycle is divided into eight gait phases. The validity of the classification results is also verified based on large gait samples. Secondly, we build a gait phase recognition model based on multilayer perceptron and train it with the phase-labeled gait data. The experimental result of cross-validation shows that the model has a 94.45% average correct rate of set (CRS and an 87.22% average correct rate of phase (CRP on the testing set, and it can predict the gait phase accurately. The novel method avoids installing additional sensors on the exoskeleton or human body and simplifies the sensory system of the lower-limb exoskeleton.

  6. Inertial Gait Phase Detection for control of a drop foot stimulator: Inertial sensing for gait phase detection

    Kotiadis, D.; Hermens, Hermanus J.; Veltink, Petrus H.

    An Inertial Gait Phase Detection system was developed to replace heel switches and footswitches currently being used for the triggering of drop foot stimulators. A series of four algorithms utilising accelerometers and gyroscopes individually and in combination were tested and initial results are

  7. Speed-Dependent Modulation of the Locomotor Behavior in Adult Mice Reveals Attractor and Transitional Gaits.

    Lemieux, Maxime; Josset, Nicolas; Roussel, Marie; Couraud, Sébastien; Bretzner, Frédéric

    2016-01-01

    Locomotion results from an interplay between biomechanical constraints of the muscles attached to the skeleton and the neuronal circuits controlling and coordinating muscle activities. Quadrupeds exhibit a wide range of locomotor gaits. Given our advances in the genetic identification of spinal and supraspinal circuits important to locomotion in the mouse, it is now important to get a better understanding of the full repertoire of gaits in the freely walking mouse. To assess this range, young adult C57BL/6J mice were trained to walk and run on a treadmill at different locomotor speeds. Instead of using the classical paradigm defining gaits according to their footfall pattern, we combined the inter-limb coupling and the duty cycle of the stance phase, thus identifying several types of gaits: lateral walk, trot, out-of-phase walk, rotary gallop, transverse gallop, hop, half-bound, and full-bound. Out-of-phase walk, trot, and full-bound were robust and appeared to function as attractor gaits (i.e., a state to which the network flows and stabilizes) at low, intermediate, and high speeds respectively. In contrast, lateral walk, hop, transverse gallop, rotary gallop, and half-bound were more transient and therefore considered transitional gaits (i.e., a labile state of the network from which it flows to the attractor state). Surprisingly, lateral walk was less frequently observed. Using graph analysis, we demonstrated that transitions between gaits were predictable, not random. In summary, the wild-type mouse exhibits a wider repertoire of locomotor gaits than expected. Future locomotor studies should benefit from this paradigm in assessing transgenic mice or wild-type mice with neurotraumatic injury or neurodegenerative disease affecting gait.

  8. Walking pattern classification and walking distance estimation algorithms using gait phase information.

    Wang, Jeen-Shing; Lin, Che-Wei; Yang, Ya-Ting C; Ho, Yu-Jen

    2012-10-01

    This paper presents a walking pattern classification and a walking distance estimation algorithm using gait phase information. A gait phase information retrieval algorithm was developed to analyze the duration of the phases in a gait cycle (i.e., stance, push-off, swing, and heel-strike phases). Based on the gait phase information, a decision tree based on the relations between gait phases was constructed for classifying three different walking patterns (level walking, walking upstairs, and walking downstairs). Gait phase information was also used for developing a walking distance estimation algorithm. The walking distance estimation algorithm consists of the processes of step count and step length estimation. The proposed walking pattern classification and walking distance estimation algorithm have been validated by a series of experiments. The accuracy of the proposed walking pattern classification was 98.87%, 95.45%, and 95.00% for level walking, walking upstairs, and walking downstairs, respectively. The accuracy of the proposed walking distance estimation algorithm was 96.42% over a walking distance.

  9. Gait Phases Recognition from Accelerations and Ground Reaction Forces: Application of Neural Networks

    S. Rafajlović

    2009-06-01

    Full Text Available The goal of this study was to test the applicability of accelerometer as the sensor for assessment of the walking. We present here the comparison of gait phases detected from the data recorded by force sensing resistors mounted in the shoe insoles, non-processed acceleration and processed acceleration perpendicular to the direction of the foot. The gait phases in all three cases were detected by means of a neural network. The output from the neural network was the gait phase, while the inputs were data from the sensors. The results show that the errors were in the ranges: 30 ms (2.7% – force sensors; 150 ms (13.6% – nonprocessed acceleration, and 120 ms (11% – processed acceleration data. This result suggests that it is possible to use the accelerometer as the gait phase detector, however, with the knowledge that the gait phases are time shifted for about 100 ms with respect the neural network predicted times.

  10. Neuromorphic walking gait control.

    Still, Susanne; Hepp, Klaus; Douglas, Rodney J

    2006-03-01

    We present a neuromorphic pattern generator for controlling the walking gaits of four-legged robots which is inspired by central pattern generators found in the nervous system and which is implemented as a very large scale integrated (VLSI) chip. The chip contains oscillator circuits that mimic the output of motor neurons in a strongly simplified way. We show that four coupled oscillators can produce rhythmic patterns with phase relationships that are appropriate to generate all four-legged animal walking gaits. These phase relationships together with frequency and duty cycle of the oscillators determine the walking behavior of a robot driven by the chip, and they depend on a small set of stationary bias voltages. We give analytic expressions for these dependencies. This chip reduces the complex, dynamic inter-leg control problem associated with walking gait generation to the problem of setting a few stationary parameters. It provides a compact and low power solution for walking gait control in robots.

  11. Assessment of a Smart Sensing Shoe for Gait Phase Detection in Level Walking

    Nicola Carbonaro

    2016-11-01

    Full Text Available Gait analysis and more specifically ambulatory monitoring of temporal and spatial gait parameters may open relevant fields of applications in activity tracking, sports and also in the assessment and treatment of specific diseases. Wearable technology can boost this scenario by spreading the adoption of monitoring systems to a wide set of healthy users or patients. In this context, we assessed a recently developed commercial smart shoe—the FootMoov—for automatic gait phase detection in level walking. FootMoov has built-in force sensors and a triaxial accelerometer and is able to transmit the sensor data to the smartphone through a wireless connection. We developed a dedicated gait phase detection algorithm relying both on force and inertial information. We tested the smart shoe on ten healthy subjects in free level walking conditions and in a laboratory setting in comparison with an optical motion capture system. Results confirmed a reliable detection of the gait phases. The maximum error committed, on the order of 44.7 ms, is comparable with previous studies. Our results confirmed the possibility to exploit consumer wearable devices to extract relevant parameters to improve the subject health or to better manage his/her progressions.

  12. Donepezil improves gait performance in older adults with mild Alzheimer's disease: a phase II clinical trial.

    Montero-Odasso, Manuel; Muir-Hunter, Susan W; Oteng-Amoako, Afua; Gopaul, Karen; Islam, Anam; Borrie, Michael; Wells, Jennie; Speechley, Mark

    2015-01-01

    Gait deficits are prevalent in people with dementia and increase their fall risk and future disability. Few treatments exist for gait impairment in Alzheimer's disease (AD) but preliminary studies have shown that cognitive enhancers may improve gait in this population. To determine the efficacy of donepezil, a cognitive enhancer that improves cholinergic activity, on gait in older adults newly diagnosed with AD. Phase II clinical trial in 43 seniors with mild AD who received donepezil. Participants had not previously received treatment with cognitive enhancers. Primary outcome variables were gait velocity (GV) and stride time variability (STV) under single and dual-task conditions measured using an electronic walkway. Secondary outcomes included attention and executive function. After four months of treatment, participants with mild AD improved their GV from 108.4 ± 18.6 to 113.3 ± 19.5 cm/s, p = 0.010; dual-task GV from 80.6 ± 23.0 to 85.3 ± 22.3 cm/s, p = 0.028. Changes in STV were in the expected direction although not statistically significant. Participants also showed improvements in Trail Making Tests A (p = 0.030), B (p = 0.001), and B-A (p = 0.042). Donepezil improved gait in participants with mild AD. The enhancement of dual-task gait suggests the positive changes achieved in executive function as a possible causal mechanism. This study yielded a clinically significant estimate of effect size; as well, the findings are relevant to the feasibility and ethics considerations for the design of a Phase III clinical trial.

  13. A Neural Network-Based Gait Phase Classification Method Using Sensors Equipped on Lower Limb Exoskeleton Robots.

    Jung, Jun-Young; Heo, Wonho; Yang, Hyundae; Park, Hyunsub

    2015-10-30

    An exact classification of different gait phases is essential to enable the control of exoskeleton robots and detect the intentions of users. We propose a gait phase classification method based on neural networks using sensor signals from lower limb exoskeleton robots. In such robots, foot sensors with force sensing registers are commonly used to classify gait phases. We describe classifiers that use the orientation of each lower limb segment and the angular velocities of the joints to output the current gait phase. Experiments to obtain the input signals and desired outputs for the learning and validation process are conducted, and two neural network methods (a multilayer perceptron and nonlinear autoregressive with external inputs (NARX)) are used to develop an optimal classifier. Offline and online evaluations using four criteria are used to compare the performance of the classifiers. The proposed NARX-based method exhibits sufficiently good performance to replace foot sensors as a means of classifying gait phases.

  14. Hemiparetic stepping to the beat: asymmetric response to metronome phase shift during treadmill gait.

    Pelton, Trudy A; Johannsen, Leif; Huiya Chen; Wing, Alan M

    2010-06-01

    Walking in time with a metronome is associated with improved spatiotemporal parameters in hemiparetic gait; however, the mechanism linking auditory and motor systems is poorly understood. Hemiparetic cadence control with metronome synchronization was examined to determine specific influences of metronome timing on treadmill walking. A within-participant experiment examined correction processes used to maintain heel strike synchrony with the beat by applying perturbations to the timing of a metronome. Eight chronic hemiparetic participants (mean age = 70 years; standard deviation = 12) were required to synchronize heel strikes with metronome pulses set according to each individual's comfortable speed (mean 0.4 m/s). During five 100-pulse trials, a fixed-phase baseline was followed by 4 unpredictable metronome phase shifts (20% of the interpulse interval), which amounted to 10 phase shifts on each foot. Infrared cameras recorded the motion of bilateral heel markers at 120 Hz. Relative asynchrony between heel strike responses and metronome pulses was used to index compensation for metronome phase shifts. Participants demonstrated compensation for phase shifts with convergence back to pre-phase shift asynchrony. This was significantly slower when the error occurred on the nonparetic side (requiring initial correction with the paretic limb) compared with when the error occurred on the paretic side (requiring initial nonparetic correction). Although phase correction of gait is slowed when the phase shift is delivered to the nonparetic side compared with the paretic side, phase correction is still present. This may underlie the utility of rhythmic auditory cueing in hemiparetic gait rehabilitation.

  15. Cycle-to-cycle control of swing phase of paraplegic gait induced by surface electrical stimulation

    Franken, H.M.; Franken, H.M.; Veltink, Petrus H.; Baardman, G.; Redmeijer, R.A.; Boom, H.B.K.

    1995-01-01

    Parameterised swing phase of gait in paraplegics was obtained using surface electrical stimulation of the hip flexors, hamstrings and quadriceps; the hip flexors were stimulated to obtain a desired hip angle range, the hamstrings to provide foot clearance in the forward swing, and the quadriceps to

  16. Changes in the referent body location and configuration may underlie human gait, as confirmed by findings of multi-muscle activity minimizations and phase resetting.

    Feldman, Anatol G; Krasovsky, Tal; Baniña, Melanie C; Lamontagne, Anouk; Levin, Mindy F

    2011-04-01

    Locomotion is presumably guided by feed-forward shifts in the referent body location in the desired direction in the environment. We propose that the difference between the actual and the referent body locations is transmitted to neurons that virtually diminish this difference by appropriately changing the referent body configuration, i.e. the body posture at which muscles reach their recruitment thresholds. Muscles are activated depending on the gap between the actual and the referent body configurations resulting in a step being made to minimize this gap. This hypothesis implies that the actual and the referent leg configurations can match each other at certain phases of the gait cycle, resulting in minimization of leg muscle activity. We found several leg configurations at which EMG minima occurred, both during forward and backward gait. It was also found that the set of limb configurations associated with EMG minima can be changed by modifying the pattern of forward and backward gait. Our hypothesis predicts that, in response to perturbations of gait, the rate of shifts in the referent body location can temporarily be changed to avoid falling. The rate influences the phase of rhythmic limb movements during gait. Therefore, following the change in the rate of the referent body location, the whole gait pattern, for all four limbs, will irreversibly be shifted in time (long-lasting and global phase resetting) with only transient changes in the gait speed, swing and stance timing and cycle duration. Aside from transient changes in the duration of the swing and/or stance phase in response to perturbation, few previous studies have documented long-lasting and global phase resetting of human gait in response to perturbation. Such resetting was a robust finding in our study. By confirming the notion that feed-forward changes in the referent body location and configuration underlie human locomotion, this study solves the classical problem in the relationship between

  17. Distal muscle activity alterations during the stance phase of gait in restless leg syndrome (RLS) patients.

    Dafkin, Chloe; Green, Andrew; Olivier, Benita; McKinon, Warrick; Kerr, Samantha

    2018-05-01

    To assess if there is a circadian variation in electromyographical (EMG) muscle activity during gait in restless legs syndrome (RLS) patients and healthy control participants. Gait assessment was done in 14 RLS patients and 13 healthy control participants in the evening (PM) and the morning (AM). Muscle activity was recorded bilaterally from the tibialis anterior (TA), lateral gastrocnemius (GL), rectus femoris (RF) and biceps femoris (BF) muscles. A circadian variation during the stance phase in only TA (PM > AM, p  Controls, p < 0.05) during early stance and decreased GL activity (RLS < Controls, p < 0.01) during terminal stance in comparison to control participants in the evening. No other significant differences were noted between RLS patients and control participants. Activation of GL during the swing phase was noted in 79% of RLS patients and in 23% of control participants in the morning compared to 71% and 38% in the evening, respectively. EMG muscle activity shows no circadian variation in RLS patients. Evening differences in gait muscle activation patterns between RLS patients and control participants are evident. These results extend our knowledge about alterations in spinal processing during gait in RLS. A possible explanation for these findings is central pattern generator sensitization caused by increased sensitivity in cutaneous afferents in RLS patients. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Insights into gait disorders: walking variability using phase plot analysis, Huntington's disease.

    Collett, Johnny; Esser, Patrick; Khalil, Hanan; Busse, Monica; Quinn, Lori; DeBono, Katy; Rosser, Anne; Nemeth, Andrea H; Dawes, Helen

    2014-09-01

    Huntington's disease (HD) is a progressive inherited neurodegenerative disorder. Identifying sensitive methodologies to quantitatively measure early motor changes have been difficult to develop. This exploratory observational study investigated gait variability and symmetry in HD using phase plot analysis. We measured the walking of 22 controls and 35 HD gene carriers (7 premanifest (PreHD)), 16 early/mid (HD1) and 12 late stage (HD2) in Oxford and Cardiff, UK. The unified Huntington's disease rating scale-total motor scores (UHDRS-TMS) and disease burden scores (DBS) were used to quantify disease severity. Data was collected during a clinical walk test (8.8 or 10 m) using an inertial measurement unit attached to the trunk. The 6 middle strides were used to calculate gait variability determined by spatiotemporal parameters (co-efficient of variation (CoV)) and phase plot analysis. Phase plots considered the variability in consecutive wave forms from vertical movement and were quantified by SDA (spatiotemporal variability), SDB (temporal variability), ratio ∀ (ratio SDA:SDB) and Δangleβ (symmetry). Step time CoV was greater in manifest HD (p0.05). Phase plot analysis identified differences between manifest HD and controls for SDB, Ratio ∀ and Δangle (all pplot analysis may be a sensitive method of detecting gait changes in HD and can be performed quickly during clinical walking tests. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Gait phase detection from sciatic nerve recordings in functional electrical stimulation systems for foot drop correction

    Chu, Jun-Uk; Song, Kang-Il; Han, Sungmin; Suh, Jun-Kyo Francis; Choi, Kuiwon; Youn, Inchan; Lee, Soo Hyun; Kang, Ji Yoon; Hwang, Dosik

    2013-01-01

    Cutaneous afferent activities recorded by a nerve cuff electrode have been used to detect the stance phase in a functional electrical stimulation system for foot drop correction. However, the implantation procedure was difficult, as the cuff electrode had to be located on the distal branches of a multi-fascicular nerve to exclude muscle afferent and efferent activities. This paper proposes a new gait phase detection scheme that can be applied to a proximal nerve root that includes cutaneous afferent fibers as well as muscle afferent and efferent fibers. To test the feasibility of this scheme, electroneurogram (ENG) signals were measured from the rat sciatic nerve during treadmill walking at several speeds, and the signal properties of the sciatic nerve were analyzed for a comparison with kinematic data from the ankle joint. On the basis of these experiments, a wavelet packet transform was tested to define a feature vector from the sciatic ENG signals according to the gait phases. We also propose a Gaussian mixture model (GMM) classifier and investigate whether it could be used successfully to discriminate feature vectors into the stance and swing phases. In spite of no significant differences in the rectified bin-integrated values between the stance and swing phases, the sciatic ENG signals could be reliably classified using the proposed wavelet packet transform and GMM classification methods. (paper)

  20. Self-Tuning Threshold Method for Real-Time Gait Phase Detection Based on Ground Contact Forces Using FSRs

    Jing Tang

    2018-02-01

    Full Text Available This paper presents a novel methodology for detecting the gait phase of human walking on level ground. The previous threshold method (TM sets a threshold to divide the ground contact forces (GCFs into on-ground and off-ground states. However, the previous methods for gait phase detection demonstrate no adaptability to different people and different walking speeds. Therefore, this paper presents a self-tuning triple threshold algorithm (STTTA that calculates adjustable thresholds to adapt to human walking. Two force sensitive resistors (FSRs were placed on the ball and heel to measure GCFs. Three thresholds (i.e., high-threshold, middle-threshold andlow-threshold were used to search out the maximum and minimum GCFs for the self-adjustments of thresholds. The high-threshold was the main threshold used to divide the GCFs into on-ground and off-ground statuses. Then, the gait phases were obtained through the gait phase detection algorithm (GPDA, which provides the rules that determine calculations for STTTA. Finally, the STTTA reliability is determined by comparing the results between STTTA and Mariani method referenced as the timing analysis module (TAM and Lopez–Meyer methods. Experimental results show that the proposed method can be used to detect gait phases in real time and obtain high reliability when compared with the previous methods in the literature. In addition, the proposed method exhibits strong adaptability to different wearers walking at different walking speeds.

  1. Asymmetry of Anticipatory Postural Adjustment During Gait Initiation

    Hiraoka Koichi

    2014-10-01

    Full Text Available The purpose of this study was to investigate the asymmetry of anticipatory postural adjustment (APA during gait initiation and to determine whether the process of choosing the initial swing leg affects APA during gait initiation. The participants initiated gait with the leg indicated by a start tone or initiated gait with the leg spontaneously chosen. The dependent variables of APA were not significantly different among the condition of initiating gait with the preferred leg indicated by the start tone, the condition of initiating gait with the non-preferred leg indicated by the start tone, and the condition of initiating gait with the leg spontaneously chosen. These findings fail to support the view that the process of choosing the initial swing leg affects APA during gait initiation. The lateral displacement of the center of pressure in the period in which shifting the center of pressure to the initial swing phase before initiating gait with the left leg indicated by the external cue was significantly larger than that when initiating gait with the right leg indicated by the external cue, and significantly larger than that when initiating gait with the leg spontaneously chosen. Weight shift to the initial swing side during APA during gait initiation was found to be asymmetrical when choosing the leg in response to an external cue

  2. Validation of Inter-Subject Training for Hidden Markov Models Applied to Gait Phase Detection in Children with Cerebral Palsy

    Juri Taborri

    2015-09-01

    Full Text Available Gait-phase recognition is a necessary functionality to drive robotic rehabilitation devices for lower limbs. Hidden Markov Models (HMMs represent a viable solution, but they need subject-specific training, making data processing very time-consuming. Here, we validated an inter-subject procedure to avoid the intra-subject one in two, four and six gait-phase models in pediatric subjects. The inter-subject procedure consists in the identification of a standardized parameter set to adapt the model to measurements. We tested the inter-subject procedure both on scalar and distributed classifiers. Ten healthy children and ten hemiplegic children, each equipped with two Inertial Measurement Units placed on shank and foot, were recruited. The sagittal component of angular velocity was recorded by gyroscopes while subjects performed four walking trials on a treadmill. The goodness of classifiers was evaluated with the Receiver Operating Characteristic. The results provided a goodness from good to optimum for all examined classifiers (0 < G < 0.6, with the best performance for the distributed classifier in two-phase recognition (G = 0.02. Differences were found among gait partitioning models, while no differences were found between training procedures with the exception of the shank classifier. Our results raise the possibility of avoiding subject-specific training in HMM for gait-phase recognition and its implementation to control exoskeletons for the pediatric population.

  3. Does a single gait training session performed either overground or on a treadmill induce specific short-term effects on gait parameters in patients with hemiparesis? A randomized controlled study.

    Bonnyaud, Céline; Pradon, Didier; Zory, Raphael; Bensmail, Djamel; Vuillerme, Nicolas; Roche, Nicolas

    2013-01-01

    Gait training for patients with hemiparesis is carried out independently overground or on a treadmill. Several studies have shown differences in hemiparetic gait parameters during overground versus treadmill walking. However, few studies have compared the effects of these 2 gait training conditions on gait parameters, and no study has compared the short-term effects of these techniques on all biomechanical gait parameters. To determine whether a gait training session performed overground or on a treadmill induces specific short-term effects on biomechanical gait parameters in patients with hemiparesis. Twenty-six subjects with hemiparesis were randomly assigned to a single session of either overground or treadmill gait training. The short-term effects on spatiotemporal, kinematic, and kinetic gait parameters were assessed using gait analysis before and immediately after the training and after a 20-minute rest. Speed, cadence, percentage of single support phase, peak knee extension, peak propulsion, and braking on the paretic side were significantly increased after the gait training session. However, there were no specific changes dependent on the type of gait training performed (overground or on a treadmill). A gait training session performed by subjects with hemiparesis overground or on a treadmill did not induce specific short-term effects on biomechanical gait parameters. The increase in gait velocity that followed a gait training session seemed to reflect specific modifications of the paretic lower limb and adaptation of the nonparetic lower limb.

  4. Phase II trial to evaluate the ActiGait implanted drop-foot stimulator in established hemiplegia

    Burridge, Jane H; Haugland, Morten; Pickering, Ruth M

    2007-01-01

    OBJECTIVE: To evaluate a selective implantable drop foot stimulator (ActiGait) in terms of effect on walking and safety. DESIGN: A phase II trial in which a consecutive sample of participants acted as their own controls. SUBJECTS: People who had suffered a stroke at least 6 months prior to recrui......OBJECTIVE: To evaluate a selective implantable drop foot stimulator (ActiGait) in terms of effect on walking and safety. DESIGN: A phase II trial in which a consecutive sample of participants acted as their own controls. SUBJECTS: People who had suffered a stroke at least 6 months prior...... to recruitment and had a drop-foot that affected walking were recruited from 3 rehabilitation centres in Denmark. METHODS: Stimulators were implanted into all participants. Outcome measures were range of ankle dorsiflexion with stimulation and maximum walking speed and distance walked in 4 minutes. Measurements...

  5. Insights into gait disorders: walking variability using phase plot analysis, Parkinson's disease.

    Esser, Patrick; Dawes, Helen; Collett, Johnny; Howells, Ken

    2013-09-01

    Gait variability may have greater utility than spatio-temporal parameters and can, be an indication for risk of falling in people with Parkinson's disease (PD). Current methods rely on prolonged data collection in order to obtain large datasets which may be demanding to obtain. We set out to explore a phase plot variability analysis to differentiate typically developed adults (TDAs) from PD obtained from two 10 m walks. Fourteen people with PD and good mobility (Rivermead Mobility Index≥8) and ten aged matched TDA were recruited and walked over 10-m at self-selected walking speed. An inertial measurement unit was placed over the projected centre of mass (CoM) sampling at 100 Hz. Vertical CoM excursion was derived to determine modelled spatiotemporal data after which the phase plot analysis was applied producing a cloud of datapoints. SDA described the spread and SDB the width of the cloud with β the angular vector of the data points. The ratio (∀) was defined as SDA: SDB. Cadence (p=.342) and stride length (p=.615) did not show a significance between TDA and PD. A difference was found for walking speed (p=.041). Furthermore a significant difference was found for β (p=.010), SDA (p=.004) other than SDB (p=.385) or ratio ∀ (p=.830). Two sequential 10-m walks showed no difference in PD for cadence (p=.193), stride length (p=.683), walking speed (p=.684) and β (p=.194), SDA (p=.051), SDB (p=.145) or ∀ (p=.226). The proposed phase plot analysis, performed on CoM motion could be used to reliably differentiate PD from TDA over a 10-m walk. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. A Novel HMM Distributed Classifier for the Detection of Gait Phases by Means of a Wearable Inertial Sensor Network

    Juri Taborri

    2014-09-01

    Full Text Available In this work, we decided to apply a hierarchical weighted decision, proposed and used in other research fields, for the recognition of gait phases. The developed and validated novel distributed classifier is based on hierarchical weighted decision from outputs of scalar Hidden Markov Models (HMM applied to angular velocities of foot, shank, and thigh. The angular velocities of ten healthy subjects were acquired via three uni-axial gyroscopes embedded in inertial measurement units (IMUs during one walking task, repeated three times, on a treadmill. After validating the novel distributed classifier and scalar and vectorial classifiers-already proposed in the literature, with a cross-validation, classifiers were compared for sensitivity, specificity, and computational load for all combinations of the three targeted anatomical segments. Moreover, the performance of the novel distributed classifier in the estimation of gait variability in terms of mean time and coefficient of variation was evaluated. The highest values of specificity and sensitivity (>0.98 for the three classifiers examined here were obtained when the angular velocity of the foot was processed. Distributed and vectorial classifiers reached acceptable values (>0.95 when the angular velocity of shank and thigh were analyzed. Distributed and scalar classifiers showed values of computational load about 100 times lower than the one obtained with the vectorial classifier. In addition, distributed classifiers showed an excellent reliability for the evaluation of mean time and a good/excellent reliability for the coefficient of variation. In conclusion, due to the better performance and the small value of computational load, the here proposed novel distributed classifier can be implemented in the real-time application of gait phases recognition, such as to evaluate gait variability in patients or to control active orthoses for the recovery of mobility of lower limb joints.

  7. Gait Analysis Using Wearable Sensors

    Tao, Weijun; Liu, Tao; Zheng, Rencheng; Feng, Hutian

    2012-01-01

    Gait analysis using wearable sensors is an inexpensive, convenient, and efficient manner of providing useful information for multiple health-related applications. As a clinical tool applied in the rehabilitation and diagnosis of medical conditions and sport activities, gait analysis using wearable sensors shows great prospects. The current paper reviews available wearable sensors and ambulatory gait analysis methods based on the various wearable sensors. After an introduction of the gait phases, the principles and features of wearable sensors used in gait analysis are provided. The gait analysis methods based on wearable sensors is divided into gait kinematics, gait kinetics, and electromyography. Studies on the current methods are reviewed, and applications in sports, rehabilitation, and clinical diagnosis are summarized separately. With the development of sensor technology and the analysis method, gait analysis using wearable sensors is expected to play an increasingly important role in clinical applications. PMID:22438763

  8. Gait Analysis Using Wearable Sensors

    Hutian Feng

    2012-02-01

    Full Text Available Gait analysis using wearable sensors is an inexpensive, convenient, and efficient manner of providing useful information for multiple health-related applications. As a clinical tool applied in the rehabilitation and diagnosis of medical conditions and sport activities, gait analysis using wearable sensors shows great prospects. The current paper reviews available wearable sensors and ambulatory gait analysis methods based on the various wearable sensors. After an introduction of the gait phases, the principles and features of wearable sensors used in gait analysis are provided. The gait analysis methods based on wearable sensors is divided into gait kinematics, gait kinetics, and electromyography. Studies on the current methods are reviewed, and applications in sports, rehabilitation, and clinical diagnosis are summarized separately. With the development of sensor technology and the analysis method, gait analysis using wearable sensors is expected to play an increasingly important role in clinical applications.

  9. A method to standardize gait and balance variables for gait velocity.

    Iersel, M.B. van; Olde Rikkert, M.G.M.; Borm, G.F.

    2007-01-01

    Many gait and balance variables depend on gait velocity, which seriously hinders the interpretation of gait and balance data derived from walks at different velocities. However, as far as we know there is no widely accepted method to correct for effects of gait velocity on other gait and balance

  10. Phase-dependent noise in Josephson junctions

    Sheldon, Forrest; Peotta, Sebastiano; Di Ventra, Massimiliano

    2018-03-01

    In addition to the usual superconducting current, Josephson junctions (JJs) support a phase-dependent conductance related to the retardation effect of tunneling quasi-particles. This introduces a dissipative current with a memory-resistive (memristive) character that should also affect the current noise. By means of the microscopic theory of tunnel junctions we compute the complete current autocorrelation function of a Josephson tunnel junction and show that this memristive component gives rise to both a previously noted phase-dependent thermal noise, and an undescribed non-stationary, phase-dependent dynamic noise. As experiments are approaching ranges in which these effects may be observed, we examine the form and magnitude of these processes. Their phase dependence can be realized experimentally as a hysteresis effect and may be used to probe defects present in JJ based qubits and in other superconducting electronics applications.

  11. Towards automated human gait disease classification using phase space representation of intrinsic mode functions

    Pratiher, Sawon; Patra, Sayantani; Pratiher, Souvik

    2017-06-01

    A novel analytical methodology for segregating healthy and neurological disorders from gait patterns is proposed by employing a set of oscillating components called intrinsic mode functions (IMF's). These IMF's are generated by the Empirical Mode Decomposition of the gait time series and the Hilbert transformed analytic signal representation forms the complex plane trace of the elliptical shaped analytic IMFs. The area measure and the relative change in the centroid position of the polygon formed by the Convex Hull of these analytic IMF's are taken as the discriminative features. Classification accuracy of 79.31% with Ensemble learning based Adaboost classifier validates the adequacy of the proposed methodology for a computer aided diagnostic (CAD) system for gait pattern identification. Also, the efficacy of several potential biomarkers like Bandwidth of Amplitude Modulation and Frequency Modulation IMF's and it's Mean Frequency from the Fourier-Bessel expansion from each of these analytic IMF's has been discussed for its potency in diagnosis of gait pattern identification and classification.

  12. Trunk Exercises Improve Gait Symmetry in Parkinson Disease: A Blind Phase II Randomized Controlled Trial.

    Hubble, Ryan P; Naughton, Geraldine; Silburn, Peter A; Cole, Michael H

    2018-03-01

    Deficits in step-to-step symmetry and trunk muscle activations have been linked to falls in Parkinson disease. Given such symptoms are poorly managed with anti-parkinsonian medications, alternate therapies are needed. This blind phase II randomized controlled trial sought to establish whether exercise can improve step-to-step symmetry in Parkinson disease. Twenty-four Parkinson disease patients with a falls history completed baseline assessments of symptom severity, balance confidence, mobility, and quality of life. Step-to-step symmetry was assessed by deriving harmonic ratios from three-dimensional accelerations collected for the head and trunk. Patients were randomly assigned to either 12 wks of exercise and falls prevention education or falls prevention education only. Both groups repeated the baseline tests 12 and 24 wks after the initial assessment. The Australian and New Zealand Clinical Trials Registry number is ACTRN12613001175763. At 12 wks, the exercise group had statistically significant and clinically relevant improvements in anterior-posterior step-to-step trunk symmetry. In contrast, the education group recorded statistically significant and clinically meaningful reductions in medial-lateral and vertical step-to-step trunk symmetry at 12 wks. Given that step-to-step symmetry improved for the exercise group and declined for the education group after intervention, active interventions seem more suited to increasing independence and quality of life for people with Parkinson disease. Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME OBJECTIVES: Upon completion of this article, the reader should be able to do the following: (1) Describe the effect deficits in trunk muscle function have on gait in individuals with Parkinson disease; (2) Identify the benefits of targeted trunk exercises on step-to-step symmetry; and (3) Discuss the benefits of improving step-to-step symmetry in individuals with Parkinson

  13. Phase dependencies of the human baroreceptor reflex

    Seidel, H.; Herzel, H.; Eckberg, D. L.

    1997-01-01

    We studied the influence of respiratory and cardiac phase on responses of the cardiac pacemaker to brief (0.35-s) increases of carotid baroreceptor afferent traffic provoked by neck suction in seven healthy young adult subjects. Cardiac responses to neck suction were measured indirectly from electrocardiographic changes of heart period. Our results show that it is possible to separate the influences of respiratory and cardiac phases at the onset of a neck suction impulse by a product of two factors: one depending only on the respiratory phase and one depending only on the cardiac phase. This result is consistent with the hypothesis that efferent vagal activity is a function of afferent baroreceptor activity, whereas respiratory neurons modulate that medullary throughput independent of the cardiac phase. Furthermore, we have shown that stimulus broadening and stimulus cropping influence the outcome of neck suction experiments in a way that makes it virtually impossible to obtain information on the phase dependency of the cardiac pacemaker's sensitivity to vagal stimulation without accurate knowledge of the functional shape of stimulus broadening.

  14. Improved Prediction of Falls in Community-Dwelling Older Adults Through Phase-Dependent Entropy of Daily-Life Walking

    Espen A. F. Ihlen

    2018-03-01

    Full Text Available Age and age-related diseases have been suggested to decrease entropy of human gait kinematics, which is thought to make older adults more susceptible to falls. In this study we introduce a new entropy measure, called phase-dependent generalized multiscale entropy (PGME, and test whether this measure improves fall-risk prediction in community-dwelling older adults. PGME can assess phase-dependent changes in the stability of gait dynamics that result from kinematic changes in events such as heel strike and toe-off. PGME was assessed for trunk acceleration of 30 s walking epochs in a re-analysis of 1 week of daily-life activity data from the FARAO study, originally described by van Schooten et al. (2016. The re-analyzed data set contained inertial sensor data from 52 single- and 46 multiple-time prospective fallers in a 6 months follow-up period, and an equal number of non-falling controls matched by age, weight, height, gender, and the use of walking aids. The predictive ability of PGME for falls was assessed using a partial least squares regression. PGME had a superior predictive ability of falls among single-time prospective fallers when compared to the other gait features. The single-time fallers had a higher PGME (p < 0.0001 of their trunk acceleration at 60% of their step cycle when compared with non-fallers. No significant differences were found between PGME of multiple-time fallers and non-fallers, but PGME was found to improve the prediction model of multiple-time fallers when combined with other gait features. These findings suggest that taking into account phase-dependent changes in the stability of the gait dynamics has additional value for predicting falls in older people, especially for single-time prospective fallers.

  15. Walking to the beat of different drums: practical implications for the use of acoustic rhythms in gait rehabilitation.

    Roerdink, Melvyn; Bank, Paulina J M; Peper, C Lieke E; Beek, Peter J

    2011-04-01

    Acoustic rhythms are frequently used in gait rehabilitation, with positive instantaneous and prolonged transfer effects on various gait characteristics. The gait modifying ability of acoustic rhythms depends on how well gait is tied to the beat, which can be assessed with measures of relative timing of auditory-motor coordination. We examined auditory-motor coordination in 20 healthy elderly individuals walking to metronome beats with pacing frequencies slower than, equal to, and faster than their preferred cadence. We found that more steps were required to adjust gait to the beat, the more the metronome rate deviated from the preferred cadence. Furthermore, participants anticipated the beat with their footfalls to various degrees, depending on the metronome rate; the faster the tempo, the smaller the phase advance or phase lead. Finally, the variability in the relative timing between footfalls and the beat was smaller for metronome rates closer to the preferred cadence, reflecting superior auditory-motor coordination. These observations have three practical implications. First, instantaneous effects of acoustic stimuli on gait characteristics may typically be underestimated given the considerable number of steps required to attune gait to the beat in combination with the usual short walkways. Second, a systematic phase lead of footfalls to the beat does not necessarily reflect a reduced ability to couple gait to the metronome. Third, the efficacy of acoustic rhythms to modify gait depends on metronome rate. Gait is coupled best to the beat for metronome rates near the preferred cadence. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Path Dependency of High Pressure Phase Transformations

    Cerreta, Ellen

    2017-06-01

    At high pressures titanium and zirconium are known to undergo a phase transformation from the hexagonal close packed (HCP), alpha-phase to the simple-hexagonal, omega-phase. Under conditions of shock loading, the high-pressure omega-phase can be retained upon release. It has been shown that temperature, peak shock stress, and texture can influence the transformation. Moreover, under these same loading conditions, plastic processes of slip and twinning are also affected by similar differences in the loading path. To understand this path dependency, in-situ velocimetry measurements along with post-mortem metallographic and neutron diffraction characterization of soft recovered specimens have been utilized to qualitatively understand the kinetics of transformation, quantify volume fraction of retained omega-phase and characterize the shocked alpha and omega-phases. Together the work described here can be utilized to map the non-equilibrium phase diagram for these metals and lend insight into the partitioning of plastic processes between phases during high pressure transformation. In collaboration with: Frank Addesssio, Curt Bronkhorst, Donald Brown, David Jones, Turab Lookman, Benjamin Morrow, Carl Trujillo, Los Alamos National Lab.; Juan Pablo Escobedo-Diaz, University of New South Wales; Paulo Rigg, Washington State University.

  17. Measurement of Phase Dependent Impedance for 3-phase Diode Rectifier

    Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth

    2016-01-01

    This paper presents a new method to measure the phase dependent impedance from an experimental set up. Though most of power electronics based system is gradually migrating to IGBT based voltage source converter due to their controllability, the rectifier composed of diode or thyristor components...

  18. Improved Leg Tracking Considering Gait Phase and Spline-Based Interpolation during Turning Motion in Walk Tests

    Ayanori Yorozu

    2015-09-01

    Full Text Available Falling is a common problem in the growing elderly population, and fall-risk assessment systems are needed for community-based fall prevention programs. In particular, the timed up and go test (TUG is the clinical test most often used to evaluate elderly individual ambulatory ability in many clinical institutions or local communities. This study presents an improved leg tracking method using a laser range sensor (LRS for a gait measurement system to evaluate the motor function in walk tests, such as the TUG. The system tracks both legs and measures the trajectory of both legs. However, both legs might be close to each other, and one leg might be hidden from the sensor. This is especially the case during the turning motion in the TUG, where the time that a leg is hidden from the LRS is longer than that during straight walking and the moving direction rapidly changes. These situations are likely to lead to false tracking and deteriorate the measurement accuracy of the leg positions. To solve these problems, a novel data association considering gait phase and a Catmull–Rom spline-based interpolation during the occlusion are proposed. From the experimental results with young people, we confirm   that the proposed methods can reduce the chances of false tracking. In addition, we verify the measurement accuracy of the leg trajectory compared to a three-dimensional motion analysis system (VICON.

  19. Contribution of the supplementary motor area and the cerebellum to the anticipatory postural adjustments and execution phases of human gait initiation.

    Richard, Aliénor; Van Hamme, Angèle; Drevelle, Xavier; Golmard, Jean-Louis; Meunier, Sabine; Welter, Marie-Laure

    2017-09-01

    Several brain structures including the brainstem, the cerebellum and the frontal cortico-basal ganglia network, with the primary and premotor areas have been shown to participate in the functional organization of gait initiation and postural control in humans, but their respective roles remain poorly understood. The aim of this study was to better understand the role of the supplementary motor area (SMA) and posterior cerebellum in the gait initiation process. Gait initiation parameters were recorded in 22 controls both before and after continuous theta burst transcranial stimulation (cTBS) of the SMA and cerebellum, and were compared to sham stimulation, using a randomized double-blind design study. The two phases of gait initiation process were analyzed: anticipatory postural adjustments (APAs) and execution, with recordings of soleus and tibialis anterior muscles. Functional inhibition of the SMA led to a shortened APA phase duration with advanced and increased muscle activity; during execution, it also advanced muscle co-activation and decreased the duration of stance soleus activity. Cerebellar functional inhibition did not influence the APA phase duration and amplitude but increased muscle co-activation, it decreased execution duration and showed a trend to increase velocity, with increased swing soleus muscle duration and activity. The results suggest that the SMA contributes to both the timing and amplitude of the APAs with no influence on step execution and the posterior cerebellum in the coupling between the APAs and execution phases and leg muscle activity pattern during gait initiation. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  20. Frequency dependence of polarization phase difference

    Rao, K.S.; Rao, Y.S.; Wang, J.R.

    1993-09-01

    Polarimetric AIRSAR data of July 13, 1990 acquired over Mahatango watershed area was processed for the identification of corn fields an forested areas. Polarization Phase Difference (PPD) values were computed for the corn fields at P-, L- and C- bands and studied as a function of frequency. The results compare well with the model calculations at 24 deg. incidence angle where as the locations of corn fields were computed to be at 35 deg. incidence angle. The discrepancy is attributed to lack of accurate ground truth and the undulating topography of the corn fields. Another study reported here deals with the usefulness of Polarization Index (PI) for the study of vegetation. PI was found to be dependent on frequency for corn fields where as for forest trees no such dependence was noticed. PI HH,HV is more useful parameter compared to PI HH,VV even for the study of corn fields. (author). 19 refs, 7 figs

  1. Supplemental Stimulation Improves Swing Phase Kinematics During Exoskeleton Assisted Gait of SCI Subjects With Severe Muscle Spasticity

    Ekelem, Andrew; Goldfarb, Michael

    2018-01-01

    Spasticity is a common comorbidity associated with spinal cord injury (SCI). Robotic exoskeletons have recently emerged to facilitate legged mobility in people with motor complete SCI. Involuntary muscle activity attributed to spasticity, however, can prevent such individuals from using an exoskeleton. Specifically, although most exoskeleton technologies can accommodate low to moderate spasticity, the presence of moderate to severe spasticity can significantly impair gait kinematics when using an exoskeleton. In an effort to potentially enable individuals with moderate to severe spasticity to use exoskeletons more effectively, this study investigates the use of common peroneal stimulation in conjunction with exoskeleton gait assistance. The electrical stimulation is timed with the exoskeleton swing phase, and is intended to acutely suppress extensor spasticity through recruitment of the flexion withdrawal reflex (i.e., while the stimulation is activated) to enable improved exoskeletal walking. In order to examine the potential efficacy of this approach, two SCI subjects with severe extensor spasticity (i.e., modified Ashworth ratings of three to four) walked in an exoskeleton with and without supplemental stimulation while knee and hip motion was measured during swing phase. Stimulation was alternated on and off every ten steps to eliminate transient therapeutic effects, enabling the acute effects of stimulation to be isolated. These experiments indicated that common peroneal stimulation on average increased peak hip flexion during the swing phase of walking by 21.1° (236%) and peak knee flexion by 14.4° (56%). Additionally, use of the stimulation decreased the swing phase RMS motor current by 228 mA (15%) at the hip motors and 734 mA (38%) at the knee motors, indicating improved kinematics were achieved with reduced effort from the exoskeleton. Walking with the exoskeleton did not have a significant effect on modified Ashworth scores, indicating the common

  2. Supplemental Stimulation Improves Swing Phase Kinematics During Exoskeleton Assisted Gait of SCI Subjects With Severe Muscle Spasticity.

    Ekelem, Andrew; Goldfarb, Michael

    2018-01-01

    Spasticity is a common comorbidity associated with spinal cord injury (SCI). Robotic exoskeletons have recently emerged to facilitate legged mobility in people with motor complete SCI. Involuntary muscle activity attributed to spasticity, however, can prevent such individuals from using an exoskeleton. Specifically, although most exoskeleton technologies can accommodate low to moderate spasticity, the presence of moderate to severe spasticity can significantly impair gait kinematics when using an exoskeleton. In an effort to potentially enable individuals with moderate to severe spasticity to use exoskeletons more effectively, this study investigates the use of common peroneal stimulation in conjunction with exoskeleton gait assistance. The electrical stimulation is timed with the exoskeleton swing phase, and is intended to acutely suppress extensor spasticity through recruitment of the flexion withdrawal reflex (i.e., while the stimulation is activated) to enable improved exoskeletal walking. In order to examine the potential efficacy of this approach, two SCI subjects with severe extensor spasticity (i.e., modified Ashworth ratings of three to four) walked in an exoskeleton with and without supplemental stimulation while knee and hip motion was measured during swing phase. Stimulation was alternated on and off every ten steps to eliminate transient therapeutic effects, enabling the acute effects of stimulation to be isolated. These experiments indicated that common peroneal stimulation on average increased peak hip flexion during the swing phase of walking by 21.1° (236%) and peak knee flexion by 14.4° (56%). Additionally, use of the stimulation decreased the swing phase RMS motor current by 228 mA (15%) at the hip motors and 734 mA (38%) at the knee motors, indicating improved kinematics were achieved with reduced effort from the exoskeleton. Walking with the exoskeleton did not have a significant effect on modified Ashworth scores, indicating the common

  3. Supplemental Stimulation Improves Swing Phase Kinematics During Exoskeleton Assisted Gait of SCI Subjects With Severe Muscle Spasticity

    Andrew Ekelem

    2018-06-01

    Full Text Available Spasticity is a common comorbidity associated with spinal cord injury (SCI. Robotic exoskeletons have recently emerged to facilitate legged mobility in people with motor complete SCI. Involuntary muscle activity attributed to spasticity, however, can prevent such individuals from using an exoskeleton. Specifically, although most exoskeleton technologies can accommodate low to moderate spasticity, the presence of moderate to severe spasticity can significantly impair gait kinematics when using an exoskeleton. In an effort to potentially enable individuals with moderate to severe spasticity to use exoskeletons more effectively, this study investigates the use of common peroneal stimulation in conjunction with exoskeleton gait assistance. The electrical stimulation is timed with the exoskeleton swing phase, and is intended to acutely suppress extensor spasticity through recruitment of the flexion withdrawal reflex (i.e., while the stimulation is activated to enable improved exoskeletal walking. In order to examine the potential efficacy of this approach, two SCI subjects with severe extensor spasticity (i.e., modified Ashworth ratings of three to four walked in an exoskeleton with and without supplemental stimulation while knee and hip motion was measured during swing phase. Stimulation was alternated on and off every ten steps to eliminate transient therapeutic effects, enabling the acute effects of stimulation to be isolated. These experiments indicated that common peroneal stimulation on average increased peak hip flexion during the swing phase of walking by 21.1° (236% and peak knee flexion by 14.4° (56%. Additionally, use of the stimulation decreased the swing phase RMS motor current by 228 mA (15% at the hip motors and 734 mA (38% at the knee motors, indicating improved kinematics were achieved with reduced effort from the exoskeleton. Walking with the exoskeleton did not have a significant effect on modified Ashworth scores, indicating the

  4. [Development of a gait trainer with regulated servo-drive for rehabilitation of locomotor disabled patients].

    Uhlenbrock, D; Sarkodie-Gyan, T; Reiter, F; Konrad, M; Hesse, S

    1997-01-01

    The aim of the present study was to develop a new gait trainer for the rehabilitation of non-ambulatory patients. For the simulation of the gait phase, we used a commercially available fitness trainer (Fast Track) with two foot plates moving in an alternating fashion and connected to a servo-controlled propulsion system providing the necessary support for the movement depending on the patient's impairment level. To compensate deficient equilibrium reflexes, the patient was suspended in a harness capable of supporting some of his/her weight. Video analysis of gait and the kinesiological EMG were used to assess the pattern of movement and the corresponding muscle activity, which were then evaluated in healthy subjects, spinal cord injured and stroke patients and compared with walking on the flat or on a treadmill. Walking on the gait trainer was characterised by a symmetrical, sinusoidal movement of lower amplitude than in normal gait. The EMG showed a low activity of the tibialis anterior muscle, while the antigravity muscles were clearly activated by the gait trainer during the stance phase. In summary, the new gait trainer generates a symmetrical gait-like movement, promoting weight acceptance in the stance phase, which is important for the restoration of walking ability.

  5. Biofeedback for robotic gait rehabilitation

    Colombo Gery

    2007-01-01

    Full Text Available Abstract Background Development and increasing acceptance of rehabilitation robots as well as advances in technology allow new forms of therapy for patients with neurological disorders. Robot-assisted gait therapy can increase the training duration and the intensity for the patients while reducing the physical strain for the therapist. Optimal training effects during gait therapy generally depend on appropriate feedback about performance. Compared to manual treadmill therapy, there is a loss of physical interaction between therapist and patient with robotic gait retraining. Thus, it is difficult for the therapist to assess the necessary feedback and instructions. The aim of this study was to define a biofeedback system for a gait training robot and test its usability in subjects without neurological disorders. Methods To provide an overview of biofeedback and motivation methods applied in gait rehabilitation, previous publications and results from our own research are reviewed. A biofeedback method is presented showing how a rehabilitation robot can assess the patients' performance and deliver augmented feedback. For validation, three subjects without neurological disorders walked in a rehabilitation robot for treadmill training. Several training parameters, such as body weight support and treadmill speed, were varied to assess the robustness of the biofeedback calculation to confounding factors. Results The biofeedback values correlated well with the different activity levels of the subjects. Changes in body weight support and treadmill velocity had a minor effect on the biofeedback values. The synchronization of the robot and the treadmill affected the biofeedback values describing the stance phase. Conclusion Robot-aided assessment and feedback can extend and improve robot-aided training devices. The presented method estimates the patients' gait performance with the use of the robot's existing sensors, and displays the resulting biofeedback

  6. Balzac and human gait analysis.

    Collado-Vázquez, S; Carrillo, J M

    2015-05-01

    People have been interested in movement analysis in general, and gait analysis in particular, since ancient times. Aristotle, Hippocrates, Galen, Leonardo da Vinci and Honoré de Balzac all used observation to analyse the gait of human beings. The purpose of this study is to compare Honoré de Balzac's writings with a scientific analysis of human gait. Honoré de Balzac's Theory of walking and other works by that author referring to gait. Honoré de Balzac had an interest in gait analysis, as demonstrated by his descriptions of characters which often include references to their way of walking. He also wrote a treatise entitled Theory of walking (Théorie de la demarche) in which he employed his keen observation skills to define gait using a literary style. He stated that the walking process is divided into phases and listed the factors that influence gait, such as personality, mood, height, weight, profession and social class, and also provided a description of the correct way of walking. Balzac considered gait analysis to be very important and this is reflected in both his character descriptions and Theory of walking, his analytical observation of gait. In our own technology-dominated times, this serves as a reminder of the importance of observation. Copyright © 2011 Sociedad Española de Neurología. Published by Elsevier España, S.L.U. All rights reserved.

  7. A mechanical energy analysis of gait initiation

    Miller, C. A.; Verstraete, M. C.

    1999-01-01

    The analysis of gait initiation (the transient state between standing and walking) is an important diagnostic tool to study pathologic gait and to evaluate prosthetic devices. While past studies have quantified mechanical energy of the body during steady-state gait, to date no one has computed the mechanical energy of the body during gait initiation. In this study, gait initiation in seven normal male subjects was studied using a mechanical energy analysis to compute total body energy. The data showed three separate states: quiet standing, gait initiation, and steady-state gait. During gait initiation, the trends in the energy data for the individual segments were similar to those seen during steady-state gait (and in Winter DA, Quanbury AO, Reimer GD. Analysis of instantaneous energy of normal gait. J Biochem 1976;9:253-257), but diminished in amplitude. However, these amplitudes increased to those seen in steady-state during the gait initiation event (GIE), with the greatest increase occurring in the second step due to the push-off of the foundation leg. The baseline level of mechanical energy was due to the potential energy of the individual segments, while the cyclic nature of the data was indicative of the kinetic energy of the particular leg in swing phase during that step. The data presented showed differences in energy trends during gait initiation from those of steady state, thereby demonstrating the importance of this event in the study of locomotion.

  8. Asymmetry of Anticipatory Postural Adjustment During Gait Initiation

    Hiraoka, Koichi; Hatanaka, Ryota; Nikaido, Yasutaka; Jono, Yasutomo; Nomura, Yoshifumi; Tani, Keisuke; Chujo, Yuta

    2014-01-01

    The purpose of this study was to investigate the asymmetry of anticipatory postural adjustment (APA) during gait initiation and to determine whether the process of choosing the initial swing leg affects APA during gait initiation. The participants initiated gait with the leg indicated by a start tone or initiated gait with the leg spontaneously chosen. The dependent variables of APA were not significantly different among the condition of initiating gait with the preferred leg indicated by the...

  9. A mechanized gait trainer for restoration of gait.

    Hesse, S; Uhlenbrock, D

    2000-01-01

    The newly developed gait trainer allows wheel-chair-bound subjects the repetitive practice of a gait-like movement without overstressing therapists. The device simulates the phases of gait, supports the subjects according to their abilities, and controls the center of mass (CoM) in the vertical and horizontal directions. The patterns of sagittal lower limb joint kinematics and of muscle activation for a normal subject were similar when using the mechanized trainer and when walking on a treadmill. A non-ambulatory hemiparetic subject required little help from one therapist on the gait trainer, while two therapists were required to support treadmill walking. Gait movements on the trainer were highly symmetrical, impact free, and less spastic. The vertical displacement of the CoM was bi-phasic instead of mono-phasic during each gait cycle on the new device. Two cases of non-ambulatory patients, who regained their walking ability after 4 weeks of daily training on the gait trainer, are reported.

  10. Effects of wide step walking on swing phase hip muscle forces and spatio-temporal gait parameters.

    Bajelan, Soheil; Nagano, Hanatsu; Sparrow, Tony; Begg, Rezaul K

    2017-07-01

    Human walking can be viewed essentially as a continuum of anterior balance loss followed by a step that re-stabilizes balance. To secure balance an extended base of support can be assistive but healthy young adults tend to walk with relatively narrower steps compared to vulnerable populations (e.g. older adults and patients). It was, therefore, hypothesized that wide step walking may enhance dynamic balance at the cost of disturbed optimum coupling of muscle functions, leading to additional muscle work and associated reduction of gait economy. Young healthy adults may select relatively narrow steps for a more efficient gait. The current study focused on the effects of wide step walking on hip abductor and adductor muscles and spatio-temporal gait parameters. To this end, lower body kinematic data and ground reaction forces were obtained using an Optotrak motion capture system and AMTI force plates, respectively, while AnyBody software was employed for muscle force simulation. A single step of four healthy young male adults was captured during preferred walking and wide step walking. Based on preferred walking data, two parallel lines were drawn on the walkway to indicate 50% larger step width and participants targeted the lines with their heels as they walked. In addition to step width that defined walking conditions, other spatio-temporal gait parameters including step length, double support time and single support time were obtained. Average hip muscle forces during swing were modeled. Results showed that in wide step walking step length increased, Gluteus Minimus muscles were more active while Gracilis and Adductor Longus revealed considerably reduced forces. In conclusion, greater use of abductors and loss of adductor forces were found in wide step walking. Further validation is needed in future studies involving older adults and other pathological populations.

  11. Temperature and phase dependence of positron lifetimes in solid cyclohexane

    Eldrup, Morten Mostgaard

    1985-01-01

    The temperature dependence of position lifetimes in both the brittle and plastic phases of cyclohaxane has been examined. Long-lived components in both phases are associated with the formation of positronium (Ps). Two long lifetimes attributable to ortho-Ps are resolvable in the plastic phase....... The longer of these (≈ 2.5 ns), which is temperature dependent, is ascribed to ortho-Ps trapped at vacancies. The shorter lifetime (≈ 0.9 ns), shows little temperature dependence. In contrast to most other plastic crystals, no sigmoidal behaviour of the average ortho-Ps lifetime is observed. A possibility...

  12. Gait performance and foot pressure distribution during wearable robot-assisted gait in elderly adults.

    Lee, Su-Hyun; Lee, Hwang-Jae; Chang, Won Hyuk; Choi, Byung-Ok; Lee, Jusuk; Kim, Jeonghun; Ryu, Gyu-Ha; Kim, Yun-Hee

    2017-11-28

    A robotic exoskeleton device is an intelligent system designed to improve gait performance and quality of life for the wearer. Robotic technology has developed rapidly in recent years, and several robot-assisted gait devices were developed to enhance gait function and activities of daily living in elderly adults and patients with gait disorders. In this study, we investigated the effects of the Gait-enhancing Mechatronic System (GEMS), a new wearable robotic hip-assist device developed by Samsung Electronics Co, Ltd., Korea, on gait performance and foot pressure distribution in elderly adults. Thirty elderly adults who had no neurological or musculoskeletal abnormalities affecting gait participated in this study. A three-dimensional (3D) motion capture system, surface electromyography and the F-Scan system were used to collect data on spatiotemporal gait parameters, muscle activity and foot pressure distribution under three conditions: free gait without robot assistance (FG), robot-assisted gait with zero torque (RAG-Z) and robot-assisted gait (RAG). We found increased gait speed, cadence, stride length and single support time in the RAG condition. Reduced rectus femoris and medial gastrocnemius muscle activity throughout the terminal stance phase and reduced effort of the medial gastrocnemius muscle throughout the pre-swing phase were also observed in the RAG condition. In addition, walking with the assistance of GEMS resulted in a significant increase in foot pressure distribution, specifically in maximum force and peak pressure of the total foot, medial masks, anterior masks and posterior masks. The results of the present study reveal that GEMS may present an alternative way of restoring age-related changes in gait such as gait instability with muscle weakness, reduced step force and lower foot pressure in elderly adults. In addition, GEMS improved gait performance by improving push-off power and walking speed and reducing muscle activity in the lower

  13. Solar Cycle Phase Dependence of Supergranular Fractal Dimension

    Solar Cycle Phase Dependence of Supergranular Fractal Dimension ... NIE Institute of Technology, Mysore, India. ... This means that each accepted article is being published immediately online with DOI and article citation ID with starting page ...

  14. Bipedal gait model for precise gait recognition and optimal triggering in foot drop stimulator: a proof of concept.

    Shaikh, Muhammad Faraz; Salcic, Zoran; Wang, Kevin I-Kai; Hu, Aiguo Patrick

    2018-03-10

    Electrical stimulators are often prescribed to correct foot drop walking. However, commercial foot drop stimulators trigger inappropriately under certain non-gait scenarios. Past researches addressed this limitation by defining stimulation control based on automaton of a gait cycle executed by foot drop of affected limb/foot only. Since gait is a collaborative activity of both feet, this research highlights the role of normal foot for robust gait detection and stimulation triggering. A novel bipedal gait model is proposed where gait cycle is realized as an automaton based on concurrent gait sub-phases (states) from each foot. The input for state transition is fused information from feet-worn pressure and inertial sensors. Thereafter, a bipedal gait model-based stimulation control algorithm is developed. As a feasibility study, bipedal gait model and stimulation control are evaluated in real-time simulation manner on normal and simulated foot drop gait measurements from 16 able-bodied participants with three speed variations, under inappropriate triggering scenarios and with foot drop rehabilitation exercises. Also, the stimulation control employed in commercial foot drop stimulators and single foot gait-based foot drop stimulators are compared alongside. Gait detection accuracy (98.9%) and precise triggering under all investigations prove bipedal gait model reliability. This infers that gait detection leveraging bipedal periodicity is a promising strategy to rectify prevalent stimulation triggering deficiencies in commercial foot drop stimulators. Graphical abstract Bipedal information-based gait recognition and stimulation triggering.

  15. A mechanized gait trainer for restoring gait in nonambulatory subjects.

    Hesse, S; Uhlenbrock, D; Werner, C; Bardeleben, A

    2000-09-01

    To construct an advanced mechanized gait trainer to enable patients the repetitive practice of a gaitlike movement without overstraining therapists. DEVICE: Prototype gait trainer that simulates the phases of gait (by generating a ratio of 40% to 60% between swing and stance phases), supports the subjects according to their ability (lifts the foot during swing phase), and controls the center of mass in the vertical and horizontal directions. Two nonambulatory, hemiparetic patients who regained their walking ability after 4 weeks of daily training on the gait trainer, a 55-year-old woman and a 62-year-old man, both of whom had a first-time ischemic stroke. Four weeks of training, five times a week, each session 20 minutes long. Functional ambulation category (FAC, levels 0-5) to assess gait ability and ground level walking velocity. Rivermead motor assessment score (RMAS, 0-13) to assess gross motor function. Patient 1: At the end of treatment, she was able to walk independently on level ground with use of a walking stick. Her walking velocity had improved from .29m/sec to .59m/sec. Her RMAS score increased from 4 to 10, meaning she could walk at least 40 meters outside, pick up objects from floor, and climb stairs independently. Patient 2: At end of 4-week training, he could walk independently on even surfaces (FAC level 4), using an ankle-foot orthosis and a walking stick. His walking velocity improved from .14m/sec to .63m/sec. His RMAS increased from 3 to 10. The gait trainer enabled severely affected patients the repetitive practice of a gaitlike movement. Future studies may elucidate its value in gait rehabilitation of nonambulatory subjects.

  16. Density-Dependent Phase Polyphenism in Nonmodel Locusts: A Minireview

    Hojun Song

    2011-01-01

    Full Text Available Although the specific mechanisms of locust phase transformation are wellunderstood for model locust species such as the desert locust Schistocerca gregaria and the migratory locust Locusta migratoria, the expressions of density-dependent phase polyphenism in other nonmodel locust species are not wellknown. The present paper is an attempt to review and synthesize what we know about these nonmodel locusts. Based on all available data, I find that locust phase polyphenism is expressed in many different ways in different locust species and identify a pattern that locust species often belong to large taxonomic groups which contain mostly nonswarming grasshopper species. Although locust phase polyphenism has evolved multiple times within Acrididae, I argue that its evolution should be studied from a phylogenetic perspective because I find similar density-dependent phenotypic plasticity among closely related species. Finally, I emphasize the importance of comparative analyses in understanding the evolution of locust phase and propose a phylogeny-based research framework.

  17. Drive frequency dependent phase imaging in piezoresponse force microscopy

    Bo Huifeng; Kan Yi; Lu Xiaomei; Liu Yunfei; Peng Song; Wang Xiaofei; Cai Wei; Xue Ruoshi; Zhu Jinsong

    2010-01-01

    The drive frequency dependent piezoresponse (PR) phase signal in near-stoichiometric lithium niobate crystals is studied by piezoresponse force microscopy. It is clearly shown that the local and nonlocal electrostatic forces have a great contribution to the PR phase signal. The significant PR phase difference of the antiparallel domains are observed at the contact resonances, which is related to the electrostatic dominated electromechanical interactions of the cantilever and tip-sample system. Moreover, the modulation voltage induced frequency shift at higher eigenmodes could be attributed to the change of indention force depending on the modulation amplitude with a piezoelectric origin. The PR phase of the silicon wafer is also measured for comparison. It is certificated that the electrostatic interactions are universal in voltage modulated scanning probe microscopy and could be extended to other phase imaging techniques.

  18. On the measurement of time-dependent quantum phases

    Barut, A.O.; Bozic, M.; Klarsfeld, S.; Maric, Z.

    1991-11-01

    We have evaluated the exact (Pancharatnam) phase differences between the final state l ψ(t) > and various initial states for a spin 1/2-particle in a rotating magnetic field B(t). For the initial states l n; B ef (0) >, which are eigenstates of the spin component along the direction of the initial effective field B ef (0), the exact phase has an energy dependent part, and an energy independent part. It is shown that these states l n; B ef (0) > are cyclic and their corresponding Aharonov-Anandan phases are evaluated. In the adiabatic limit we discuss different choices of time-dependent bases and the relationship between the exact phase, the Born-Fock-Schiff phase and Berry's phase. We propose experiments (neutron) to verify separately the exact and the adiabatic evolution laws, as well as to measure the adiabatic phases associated with different choices of time-dependent basis vectors. (author). 37 refs, 5 figs, 1 tab

  19. Time-dependent phase error correction using digital waveform synthesis

    Doerry, Armin W.; Buskirk, Stephen

    2017-10-10

    The various technologies presented herein relate to correcting a time-dependent phase error generated as part of the formation of a radar waveform. A waveform can be pre-distorted to facilitate correction of an error induced into the waveform by a downstream operation/component in a radar system. For example, amplifier power droop effect can engender a time-dependent phase error in a waveform as part of a radar signal generating operation. The error can be quantified and an according complimentary distortion can be applied to the waveform to facilitate negation of the error during the subsequent processing of the waveform. A time domain correction can be applied by a phase error correction look up table incorporated into a waveform phase generator.

  20. The Combined Effects of Body Weight Support and Gait Speed on Gait Related Muscle Activity: A Comparison between Walking in the Lokomat Exoskeleton and Regular Treadmill Walking

    Van Kammen, Klaske; Boonstra, Annemarijke; Reinders-Messelink, Heleen; den Otter, Rob

    2014-01-01

    Background For the development of specialized training protocols for robot assisted gait training, it is important to understand how the use of exoskeletons alters locomotor task demands, and how the nature and magnitude of these changes depend on training parameters. Therefore, the present study assessed the combined effects of gait speed and body weight support (BWS) on muscle activity, and compared these between treadmill walking and walking in the Lokomat exoskeleton. Methods Ten healthy participants walked on a treadmill and in the Lokomat, with varying levels of BWS (0% and 50% of the participants’ body weight) and gait speed (0.8, 1.8, and 2.8 km/h), while temporal step characteristics and muscle activity from Erector Spinae, Gluteus Medius, Vastus Lateralis, Biceps Femoris, Gastrocnemius Medialis, and Tibialis Anterior muscles were recorded. Results The temporal structure of the stepping pattern was altered when participants walked in the Lokomat or when BWS was provided (i.e. the relative duration of the double support phase was reduced, and the single support phase prolonged), but these differences normalized as gait speed increased. Alternations in muscle activity were characterized by complex interactions between walking conditions and training parameters: Differences between treadmill walking and walking in the exoskeleton were most prominent at low gait speeds, and speed effects were attenuated when BWS was provided. Conclusion Walking in the Lokomat exoskeleton without movement guidance alters the temporal step regulation and the neuromuscular control of walking, although the nature and magnitude of these effects depend on complex interactions with gait speed and BWS. If normative neuromuscular control of gait is targeted during training, it is recommended that very low speeds and high levels of BWS should be avoided when possible. PMID:25226302

  1. Modeling and simulation of normal and hemiparetic gait

    Luengas, Lely A.; Camargo, Esperanza; Sanchez, Giovanni

    2015-09-01

    Gait is the collective term for the two types of bipedal locomotion, walking and running. This paper is focused on walking. The analysis of human gait is of interest to many different disciplines, including biomechanics, human-movement science, rehabilitation and medicine in general. Here we present a new model that is capable of reproducing the properties of walking, normal and pathological. The aim of this paper is to establish the biomechanical principles that underlie human walking by using Lagrange method. The constraint forces of Rayleigh dissipation function, through which to consider the effect on the tissues in the gait, are included. Depending on the value of the factor present in the Rayleigh dissipation function, both normal and pathological gait can be simulated. First of all, we apply it in the normal gait and then in the permanent hemiparetic gait. Anthropometric data of adult person are used by simulation, and it is possible to use anthropometric data for children but is necessary to consider existing table of anthropometric data. Validation of these models includes simulations of passive dynamic gait that walk on level ground. The dynamic walking approach provides a new perspective of gait analysis, focusing on the kinematics and kinetics of gait. There have been studies and simulations to show normal human gait, but few of them have focused on abnormal, especially hemiparetic gait. Quantitative comparisons of the model predictions with gait measurements show that the model can reproduce the significant characteristics of normal gait.

  2. First signs of elderly gait for women.

    Kaczmarczyk, Katarzyna; Wiszomirska, Ida; Błażkiewicz, Michalina; Wychowański, Michał; Wit, Andrzej

    2017-06-27

    The aims of this study have been twofold: to attempt to reduce the number of spatiotemporal parameters used for describing gait through the factor analysis and component analysis; and to explore the critical age of decline for other gait parameters for healthy women. A total of 106 women (aged ≥ 40 years old (N = 76) and ≤ 31 years old (N = 30)) were evaluated using a pressure-sensitive mat (Zebris Medical System, Tübingen, Germany) for collecting spatiotemporal gait parameters. The factor analysis identified 2 factors - labelled Time and Rhythm - that accounted for 72% of the variation in significant free-gait parameters; the principal component analysis identified 4 of these parameters that permit full clinical evaluation of gait quality. No difference was found between the groups in terms of the values of parameters reflecting the temporal nature of gait (Rhythm), namely step time, stride time and cadence, whereas significant differences were found for total double support phase (p gait, we selected 3 parameters: total double support, stride time and velocity. We concluded that the women taking part in the experiment manifested significant signs of senile gait after the age of 60 years old, with the first symptoms thereof already manifesting themselves after 50 years of age. We show that among 26 spatiotemporal parameters that may be used for characterizing gait, at least a half of them may be omitted in the assessment of gait correctness; a finding that may be useful in clinical practice. The finding that the onset of senile gait occurs in the case of women after the age of 60 years old, in turn, may be useful in evaluating the ability for performing types of physical work that mainly require ambulation. Med Pr 2017;68(4):441-448. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  3. Nuclear ``pasta'' phase within density dependent hadronic models

    Avancini, S. S.; Brito, L.; Marinelli, J. R.; Menezes, D. P.; de Moraes, M. M. W.; Providência, C.; Santos, A. M.

    2009-03-01

    In the present paper, we investigate the onset of the “pasta” phase with different parametrizations of the density dependent hadronic model and compare the results with one of the usual parametrizations of the nonlinear Walecka model. The influence of the scalar-isovector virtual δ meson is shown. At zero temperature, two different methods are used, one based on coexistent phases and the other on the Thomas-Fermi approximation. At finite temperature, only the coexistence phases method is used. npe matter with fixed proton fractions and in β equilibrium are studied. We compare our results with restrictions imposed on the values of the density and pressure at the inner edge of the crust, obtained from observations of the Vela pulsar and recent isospin diffusion data from heavy-ion reactions, and with predictions from spinodal calculations.

  4. Nuclear 'pasta' phase within density dependent hadronic models

    Avancini, S. S.; Marinelli, J. R.; Menezes, D. P.; Moraes, M. M. W. de; Brito, L.; Providencia, C.; Santos, A. M.

    2009-01-01

    In the present paper, we investigate the onset of the 'pasta' phase with different parametrizations of the density dependent hadronic model and compare the results with one of the usual parametrizations of the nonlinear Walecka model. The influence of the scalar-isovector virtual δ meson is shown. At zero temperature, two different methods are used, one based on coexistent phases and the other on the Thomas-Fermi approximation. At finite temperature, only the coexistence phases method is used. npe matter with fixed proton fractions and in β equilibrium are studied. We compare our results with restrictions imposed on the values of the density and pressure at the inner edge of the crust, obtained from observations of the Vela pulsar and recent isospin diffusion data from heavy-ion reactions, and with predictions from spinodal calculations

  5. Pulse Phase Dependence of the Magnetar Bursts Chetana Jain ...

    Gamma rays: bursts—neutron stars, magnetars: individual. (SGR 1806–20 ... the pulse profiles and pulsed and unpulsed X-ray flux are known to vary with time. ... that can be modeled by thermal emission of kT ∼0.5 keV along with a power law ... detection of the bursts is expected to be dependent on the pulse phase. 2.

  6. Vector-field statistics for the analysis of time varying clinical gait data.

    Donnelly, C J; Alexander, C; Pataky, T C; Stannage, K; Reid, S; Robinson, M A

    2017-01-01

    In clinical settings, the time varying analysis of gait data relies heavily on the experience of the individual(s) assessing these biological signals. Though three dimensional kinematics are recognised as time varying waveforms (1D), exploratory statistical analysis of these data are commonly carried out with multiple discrete or 0D dependent variables. In the absence of an a priori 0D hypothesis, clinicians are at risk of making type I and II errors in their analyis of time varying gait signatures in the event statistics are used in concert with prefered subjective clinical assesment methods. The aim of this communication was to determine if vector field waveform statistics were capable of providing quantitative corroboration to practically significant differences in time varying gait signatures as determined by two clinically trained gait experts. The case study was a left hemiplegic Cerebral Palsy (GMFCS I) gait patient following a botulinum toxin (BoNT-A) injection to their left gastrocnemius muscle. When comparing subjective clinical gait assessments between two testers, they were in agreement with each other for 61% of the joint degrees of freedom and phases of motion analysed. For tester 1 and tester 2, they were in agreement with the vector-field analysis for 78% and 53% of the kinematic variables analysed. When the subjective analyses of tester 1 and tester 2 were pooled together and then compared to the vector-field analysis, they were in agreement for 83% of the time varying kinematic variables analysed. These outcomes demonstrate that in principle, vector-field statistics corroborates with what a team of clinical gait experts would classify as practically meaningful pre- versus post time varying kinematic differences. The potential for vector-field statistics to be used as a useful clinical tool for the objective analysis of time varying clinical gait data is established. Future research is recommended to assess the usefulness of vector-field analyses

  7. Gait Partitioning Methods: A Systematic Review

    Taborri, Juri; Palermo, Eduardo; Rossi, Stefano; Cappa, Paolo

    2016-01-01

    In the last years, gait phase partitioning has come to be a challenging research topic due to its impact on several applications related to gait technologies. A variety of sensors can be used to feed algorithms for gait phase partitioning, mainly classifiable as wearable or non-wearable. Among wearable sensors, footswitches or foot pressure insoles are generally considered as the gold standard; however, to overcome some inherent limitations of the former, inertial measurement units have become popular in recent decades. Valuable results have been achieved also though electromyography, electroneurography, and ultrasonic sensors. Non-wearable sensors, such as opto-electronic systems along with force platforms, remain the most accurate system to perform gait analysis in an indoor environment. In the present paper we identify, select, and categorize the available methodologies for gait phase detection, analyzing advantages and disadvantages of each solution. Finally, we comparatively examine the obtainable gait phase granularities, the usable computational methodologies and the optimal sensor placements on the targeted body segments. PMID:26751449

  8. Gait Partitioning Methods: A Systematic Review

    Juri Taborri

    2016-01-01

    Full Text Available In the last years, gait phase partitioning has come to be a challenging research topic due to its impact on several applications related to gait technologies. A variety of sensors can be used to feed algorithms for gait phase partitioning, mainly classifiable as wearable or non-wearable. Among wearable sensors, footswitches or foot pressure insoles are generally considered as the gold standard; however, to overcome some inherent limitations of the former, inertial measurement units have become popular in recent decades. Valuable results have been achieved also though electromyography, electroneurography, and ultrasonic sensors. Non-wearable sensors, such as opto-electronic systems along with force platforms, remain the most accurate system to perform gait analysis in an indoor environment. In the present paper we identify, select, and categorize the available methodologies for gait phase detection, analyzing advantages and disadvantages of each solution. Finally, we comparatively examine the obtainable gait phase granularities, the usable computational methodologies and the optimal sensor placements on the targeted body segments.

  9. Are the Kinematics of the Knee Joint Altered during the Loading Response Phase of Gait in Individuals with Concurrent Knee Osteoarthritis and Complaints of Joint Instability? A Dynamic Stereo X-ray Study

    Farrokhi, Shawn; Tashman, Scott; Gil, Alexandra B.; Klatt, Brian A.; Fitzgerald, G. Kelley

    2011-01-01

    Background Joint instability has been suggested as a risk factor for knee osteoarthritis and a cause of significant functional declines in those with symptomatic disease. However, the relationship between altered knee joint mechanics and self-reports of instability in individuals with knee osteoarthritis remains unclear. Methods Fourteen subjects with knee osteoarthritis and complaints of joint instability and 12 control volunteers with no history of knee disease were recruited for this study. Dynamic stereo X-ray technology was used to assess the three-dimensional kinematics of the knee joint during the loading response phase of gait. Findings Individuals with concurrent knee osteoarthritis and joint instability demonstrated significantly reduced flexion and internal/external rotation knee motion excursions during the loading response phase of gait (P knee joint at initial contact was significantly different (P knee osteoarthritis and joint instability. However, the anteroposterior and mediolateral tibiofemoral joint positions at initial contact and the corresponding total joint translations were similar between groups during the loading phase of gait. Interpretations The rotational patterns of tibiofemoral joint motion and joint alignments reported for individuals with concurrent knee osteoarthritis and joint instability are consistent with those previously established for individuals with knee osteoarthritis. Furthermore, the findings of similar translatory tibiofemoral motion between groups suggest that self-reports of episodic joint instability in individuals with knee osteoarthritis may not necessarily be associated with adaptive alterations in joint arthrokinematics. PMID:22071429

  10. Are the kinematics of the knee joint altered during the loading response phase of gait in individuals with concurrent knee osteoarthritis and complaints of joint instability? A dynamic stereo X-ray study.

    Farrokhi, Shawn; Tashman, Scott; Gil, Alexandra B; Klatt, Brian A; Fitzgerald, G Kelley

    2012-05-01

    Joint instability has been suggested as a risk factor for knee osteoarthritis and a cause of significant functional decline in those with symptomatic disease. However, the relationship between altered knee joint mechanics and self-reports of instability in individuals with knee osteoarthritis remains unclear. Fourteen subjects with knee osteoarthritis and complaints of joint instability and 12 control volunteers with no history of knee disease were recruited for this study. Dynamic stereo X-ray technology was used to assess the three-dimensional kinematics of the knee joint during the loading response phase of gait. Individuals with concurrent knee osteoarthritis and joint instability demonstrated significantly reduced flexion and internal/external rotation knee motion excursions during the loading response phase of gait (Pknee joint at initial contact was significantly different (Pknee osteoarthritis and joint instability. However, the anteroposterior and mediolateral tibiofemoral joint positions at initial contact and the corresponding total joint translations were similar between groups during the loading phase of gait. The rotational patterns of tibiofemoral joint motion and joint alignments reported for individuals with concurrent knee osteoarthritis and joint instability are consistent with those previously established for individuals with knee osteoarthritis. Furthermore, the findings of similar translatory tibiofemoral motion between groups suggest that self-reports of episodic joint instability in individuals with knee osteoarthritis may not necessarily be associated with adaptive alterations in joint arthrokinematics. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. Evidence of end-effector based gait machines in gait rehabilitation after CNS lesion.

    Hesse, S; Schattat, N; Mehrholz, J; Werner, C

    2013-01-01

    A task-specific repetitive approach in gait rehabilitation after CNS lesion is well accepted nowadays. To ease the therapists' and patients' physical effort, the past two decades have seen the introduction of gait machines to intensify the amount of gait practice. Two principles have emerged, an exoskeleton- and an endeffector-based approach. Both systems share the harness and the body weight support. With the end-effector-based devices, the patients' feet are positioned on two foot plates, whose movements simulate stance and swing phase. This article provides an overview on the end-effector based machine's effectiveness regarding the restoration of gait. For the electromechanical gait trainer GT I, a meta analysis identified nine controlled trials (RCT) in stroke subjects (n = 568) and were analyzed to detect differences between end-effector-based locomotion + physiotherapy and physiotherapy alone. Patients practising with the machine effected in a superior gait ability (210 out of 319 patients, 65.8% vs. 96 out of 249 patients, 38.6%, respectively, Z = 2.29, p = 0.020), due to a larger training intensity. Only single RCTs have been reported for other devices and etiologies. The introduction of end-effector based gait machines has opened a new succesful chapter in gait rehabilitation after CNS lesion.

  12. Gait parameters in patients with diabetes mellitus

    Cristina Elena Prado Teles Fregonesi

    2010-02-01

    Full Text Available Diabetes mellitus is a chronic disease that results in sensorimotor alterations. These changes affect balance and walking and predispose affected patients to falls. The aim of this review was to identify studies in the recent literature that assess gait parameters and aspects involved in walking. The MEDLINE, SciELO, LILACS and PEDro databases were searched using the following combination of keywords: diabetic neuropathies x gait; diabetes mellitus x gait, and diabetic foot x gait. After the application of selection criteria, 15 articles were retrieved, summarized, discussed, and are included in this review. Diabetic neuropathy was found to lead to deficits in step amplitude, gait velocity and gait cadence on flat surfaces, without sudden changes in direction or stops, and to balance and coordination deficits on inclined and uneven terrain. Diabetic neuropathies also increase plantar pressure rates and lead to difficulties in the terminal stance phase and pre-swing phase due to changes in triceps surae activation. Thus, the next initial contact occurs in an inadequate manner, with the forefoot and without absorption of shocks.

  13. Walking to the beat of different drums: Practical implications for the use of acoustic rhythms in gait rehabilitation

    Roerdink, M.; Bank, P.J.M.; Peper, C.E.; Beek, P.J.

    2011-01-01

    Acoustic rhythms are frequently used in gait rehabilitation, with positive instantaneous and prolonged transfer effects on various gait characteristics. The gait modifying ability of acoustic rhythms depends on how well gait is tied to the beat, which can be assessed with measures of relative timing

  14. Competing failure analysis in phased-mission systems with functional dependence in one of phases

    Wang, Chaonan; Xing, Liudong; Levitin, Gregory

    2012-01-01

    This paper proposes an algorithm for the reliability analysis of non-repairable phased-mission systems (PMS) subject to competing failure propagation and isolation effects. A failure originating from a system component which causes extensive damage to other system components is a propagated failure. When the propagated failure affects all the system components, causing the entire system failure, a propagated failure with global effect (PFGE) is said to occur. However, the failure propagation can be isolated in systems subject to functional dependence (FDEP) behavior, where the failure of a component (referred to as trigger component) causes some other components (referred to as dependent components) to become inaccessible or unusable (isolated from the system), and thus further failures from these dependent components have no effect on the system failure behavior. On the other hand, if any PFGE from dependent components occurs before the trigger failure, the failure propagation effect takes place, causing the overall system failure. In summary, there are two distinct consequences of a PFGE due to the competition between the failure isolation and failure propagation effects in the time domain. Existing works on such competing failures focus only on single-phase systems. However, many real-world systems are phased-mission systems (PMS), which involve multiple, consecutive and non-overlapping phases of operations or tasks. Consideration of competing failures for PMS is a challenging and difficult task because PMS exhibit dynamics in the system configuration and component behavior as well as statistical dependencies across phases for a given component. This paper proposes a combinatorial method to address the competing failure effects in the reliability analysis of binary non-repairable PMS. The proposed method is verified using a Markov-based method through a numerical example. Different from the Markov-based approach that is limited to exponential distribution, the

  15. Gait as evidence

    Lynnerup, Niels; Larsen, Peter Kastmand

    2014-01-01

    This study examines what in Denmark may constitute evidence based on forensic anthropological gait analyses, in the sense of pointing to a match (or not) between a perpetrator and a suspect, based on video and photographic imagery. Gait and anthropometric measures can be used when direct facial...

  16. Computing the variations in the self-similar properties of the various gait intervals in Parkinson disease patients.

    Manjeri Keloth, Sana; Arjunan, Sridhar P; Kumar, Dinesh

    2017-07-01

    This study has investigated the stride, swing, stance and double support intervals of gait for Parkinson's disease (PD) patients with different levels of severity. Self-similar properties of the gait signal were analyzed to investigate the changes in the gait pattern of the healthy and PD patients. To understand the self-similar property, detrended fluctuation analysis was performed. The analysis shows that the PD patients have less defined gait when compared to healthy. The study also shows that among the stance and swing phase of stride interval, the self-similarity is less for swing interval when compared to the stance interval of gait and decreases with the severity of gait. Also, PD patients show decreased self-similar patterns in double support interval of gait. This suggest that there are less rhythmic gait intervals and a sense of urgency to remain in support phase of gait by the PD patients.

  17. Gait Analysis by Multi Video Sequence Analysis

    Jensen, Karsten; Juhl, Jens

    2009-01-01

    The project presented in this article aims to develop software so that close-range photogrammetry with sufficient accuracy can be used to point out the most frequent foot mal positions and monitor the effect of the traditional treatment. The project is carried out as a cooperation between...... and the calcaneus angle during gait. In the introductory phase of the project the task has been to select, purchase and draw up hardware, select and purchase software concerning video streaming and to develop special software concerning automated registration of the position of the foot during gait by Multi Video...

  18. Influence of Velocity on Variability in Gait Kinematics

    Yang, Sylvia X M; Larsen, Peter K; Alkjær, Tine

    2014-01-01

    the concurrence of joint angles throughout a gait cycle at three different velocities (3.0, 4.5, 6.0 km/h). Six datasets at each velocity were collected from 16 men. A variability range VR throughout the gait cycle at each velocity for each joint angle for each person was calculated. The joint angles at each...... velocity were compared pairwise, and whenever this showed values within the VR of this velocity, the case was positive. By adding the positives throughout the gait cycle, phases with high and low concurrences were located; peak concurrence was observed at mid-stance phase. Striving for the same velocity...

  19. Quantitative Gait Analysis in Patients with Huntington’s Disease

    Seon Jong Pyo

    2017-09-01

    Full Text Available Objective Gait disturbance is the main factor contributing to a negative impact on quality of life in patients with Huntington’s disease (HD. Understanding gait features in patients with HD is essential for planning a successful gait strategy. The aim of this study was to investigate temporospatial gait parameters in patients with HD compared with healthy controls. Methods We investigated 7 patients with HD. Diagnosis was confirmed by genetic analysis, and patients were evaluated with the Unified Huntington’s Disease Rating Scale (UHDRS. Gait features were assessed with a gait analyzer. We compared the results of patients with HD to those of 7 age- and sex-matched normal controls. Results Step length and stride length were decreased and base of support was increased in the HD group compared to the control group. In addition, coefficients of variability for step and stride length were increased in the HD group. The HD group showed slower walking velocity, an increased stance/swing phase in the gait cycle and a decreased proportion of single support time compared to the control group. Cadence did not differ significantly between groups. Among the UHDRS subscores, total motor score and total behavior score were positively correlated with step length, and total behavior score was positively correlated with walking velocity in patients with HD. Conclusion Increased variability in step and stride length, slower walking velocity, increased stance phase, and decreased swing phase and single support time with preserved cadence suggest that HD gait patterns are slow, ataxic and ineffective. This study suggests that quantitative gait analysis is needed to assess gait problems in HD.

  20. Kinematics gait disorder in men with fibromyalgia.

    Heredia-Jimenez, Jose M; Soto-Hermoso, Victor M

    2014-01-01

    The aim of this study was to assess the kinematics disorder of gait in men with fibromyalgia. We studied 12 male with fibromyalgia and 14 healthy men. Each participant of the study walked five trials along a 18.6-m walkway. Fibromyalgia patients completed a Spanish version of Fibromyalgia Impact Questionnaire. Significant differences between fibromyalgia and control groups were found in velocity, stride length, and cadence. Gait parameters of men affected by fibromyalgia were impaired when compared to those of healthy group due to bradykinesia. According to previous studies to assess gait variables in female patients, the male with fibromyalgia also showed lower values of velocity, cadence, and stride length than healthy group but not reported significant differences in swing, stance, single, or double support phase.

  1. Quantifying gait patterns in Parkinson's disease

    Romero, Mónica; Atehortúa, Angélica; Romero, Eduardo

    2017-11-01

    Parkinson's disease (PD) is constituted by a set of motor symptoms, namely tremor, rigidity, and bradykinesia, which are usually described but not quantified. This work proposes an objective characterization of PD gait patterns by approximating the single stance phase a single grounded pendulum. This model estimates the force generated by the gait during the single support from gait data. This force describes the motion pattern for different stages of the disease. The model was validated using recorded videos of 8 young control subjects, 10 old control subjects and 10 subjects with Parkinson's disease in different stages. The estimated force showed differences among stages of Parkinson disease, observing a decrease of the estimated force for the advanced stages of this illness.

  2. Development of an advanced mechanised gait trainer, controlling movement of the centre of mass, for restoring gait in non-ambulant subjects.

    Hesse, S; Sarkodie-Gyan, T; Uhlenbrock, D

    1999-01-01

    The study aimed at further development of a mechanised gait trainer which would allow non-ambulant people to practice a gait-like motion repeatedly. To simulate normal gait, discrete stance and swing phases, lasting 60% and 40% of the gait cycle respectively, and the control of the movement of the centre of mass were required. A complex gear system provided the gait-like movement of two foot plates with a ratio of 60% to 40% between the stance and swing phases. A controlled propulsion system adjusted its output according to patient's efforts. Two eccenters on the central gear controlled phase-adjusted the vertical and horizontal position of the centre of mass. The patterns of sagittal lower limb joint kinematics and of muscle activation of a normal subject were similar when using the mechanised trainer and when walking on a treadmill. A non-ambulatory hemiparetic subject required little help from one therapist on the gait trainer, while two therapists supported treadmill walking. Gait movements on the trainer were highly symmetrical, impact-free, and less spastic. The weight-bearing muscles were activated in a similar fashion during both conditions. The vertical displacement of the centre of mass was bi-instead of mono-phasic during each gait cycle on the new device. In conclusion, the gait trainer allowed wheelchair-bound subjects the repetitive practice of a gait-like movement without overstraining therapists.

  3. Robot-Crawler: Statically Balanced Gaits

    S. Parasuraman

    2012-12-01

    Full Text Available This paper presents a new statically balanced walking technique for a robot-crawler. The gait design and the control of the robot crawler aim to achieve stability while walking. This statically balanced gait has to be designed in a different fashion to a wheeled robot, as there are discrete changes in the support of the robot when its legs are lifted or placed on the ground. The stability of the robot depends on how the legs are positioned relative to the body and also on the sequence and timing with which the legs are lifted and placed. In order to reduce the risk of stability loss while walking, a measure for the robot stability (so-called stability margin is typically used in the gait and motion planning. In this paper different biological behaviours of four-legged animals are studied and mapped on a quad-legrobot-crawler. Experiments were carried out on the forward walking gaits of lizards and horses. Based on these results, the stability margins of different gaits are discussed and compared.

  4. Gait rehabilitation machines based on programmable footplates.

    Schmidt, Henning; Werner, Cordula; Bernhardt, Rolf; Hesse, Stefan; Krüger, Jörg

    2007-02-09

    Gait restoration is an integral part of rehabilitation of brain lesioned patients. Modern concepts favour a task-specific repetitive approach, i.e. who wants to regain walking has to walk, while tone-inhibiting and gait preparatory manoeuvres had dominated therapy before. Following the first mobilization out of the bed, the wheelchair-bound patient should have the possibility to practise complex gait cycles as soon as possible. Steps in this direction were treadmill training with partial body weight support and most recently gait machines enabling the repetitive training of even surface gait and even of stair climbing. With treadmill training harness-secured and partially relieved wheelchair-mobilised patients could practise up to 1000 steps per session for the first time. Controlled trials in stroke and SCI patients, however, failed to show a superior result when compared to walking exercise on the floor. Most likely explanation was the effort for the therapists, e.g. manually setting the paretic limbs during the swing phase resulting in a too little gait intensity. The next steps were gait machines, either consisting of a powered exoskeleton and a treadmill (Lokomat, AutoAmbulator) or an electromechanical solution with the harness secured patient placed on movable foot plates (Gait Trainer GT I). For the latter, a large multi-centre trial with 155 non-ambulatory stroke patients (DEGAS) revealed a superior gait ability and competence in basic activities of living in the experimental group. The HapticWalker continued the end effector concept of movable foot plates, now fully programmable and equipped with 6 DOF force sensors. This device for the first time enables training of arbitrary walking situations, hence not only the simulation of floor walking but also for example of stair climbing and perturbations. Locomotor therapy is a fascinating new tool in rehabilitation, which is in line with modern principles of motor relearning promoting a task-specific repetitive

  5. Gait rehabilitation machines based on programmable footplates

    Bernhardt Rolf

    2007-02-01

    Full Text Available Abstract Background Gait restoration is an integral part of rehabilitation of brain lesioned patients. Modern concepts favour a task-specific repetitive approach, i.e. who wants to regain walking has to walk, while tone-inhibiting and gait preparatory manoeuvres had dominated therapy before. Following the first mobilization out of the bed, the wheelchair-bound patient should have the possibility to practise complex gait cycles as soon as possible. Steps in this direction were treadmill training with partial body weight support and most recently gait machines enabling the repetitive training of even surface gait and even of stair climbing. Results With treadmill training harness-secured and partially relieved wheelchair-mobilised patients could practise up to 1000 steps per session for the first time. Controlled trials in stroke and SCI patients, however, failed to show a superior result when compared to walking exercise on the floor. Most likely explanation was the effort for the therapists, e.g. manually setting the paretic limbs during the swing phase resulting in a too little gait intensity. The next steps were gait machines, either consisting of a powered exoskeleton and a treadmill (Lokomat, AutoAmbulator or an electromechanical solution with the harness secured patient placed on movable foot plates (Gait Trainer GT I. For the latter, a large multi-centre trial with 155 non-ambulatory stroke patients (DEGAS revealed a superior gait ability and competence in basic activities of living in the experimental group. The HapticWalker continued the end effector concept of movable foot plates, now fully programmable and equipped with 6 DOF force sensors. This device for the first time enables training of arbitrary walking situations, hence not only the simulation of floor walking but also for example of stair climbing and perturbations. Conclusion Locomotor therapy is a fascinating new tool in rehabilitation, which is in line with modern principles

  6. Gait and its assessment in psychiatry

    Sanders, Richard D.; Gillig, Paulette Marie

    2010-01-01

    Gait reflects all levels of nervous system function. In psychiatry, gait disturbances reflecting cortical and subcortical dysfunction are often seen. Observing spontaneous gait, sometimes augmented by a few brief tests, can be highly informative. The authors briefly review the neuroanatomy of gait, review gait abnormalities seen in psychiatric and neurologic disorders, and describe the assessment of gait.

  7. Kinematic analysis quantifies gait abnormalities associated with lameness in broiler chickens and identifies evolutionary gait differences.

    Gina Caplen

    Full Text Available This is the first time that gait characteristics of broiler (meat chickens have been compared with their progenitor, jungle fowl, and the first kinematic study to report a link between broiler gait parameters and defined lameness scores. A commercial motion-capturing system recorded three-dimensional temporospatial information during walking. The hypothesis was that the gait characteristics of non-lame broilers (n = 10 would be intermediate to those of lame broilers (n = 12 and jungle fowl (n = 10, tested at two ages: immature and adult. Data analysed using multi-level models, to define an extensive range of baseline gait parameters, revealed inter-group similarities and differences. Natural selection is likely to have made jungle fowl walking gait highly efficient. Modern broiler chickens possess an unbalanced body conformation due to intense genetic selection for additional breast muscle (pectoral hypertrophy and whole body mass. Together with rapid growth, this promotes compensatory gait adaptations to minimise energy expenditure and triggers high lameness prevalence within commercial flocks; lameness creating further disruption to the gait cycle and being an important welfare issue. Clear differences were observed between the two lines (short stance phase, little double-support, low leg lift, and little back displacement in adult jungle fowl; much double-support, high leg lift, and substantial vertical back movement in sound broilers presumably related to mass and body conformation. Similarities included stride length and duration. Additional modifications were also identified in lame broilers (short stride length and duration, substantial lateral back movement, reduced velocity presumably linked to musculo-skeletal abnormalities. Reduced walking velocity suggests an attempt to minimise skeletal stress and/or discomfort, while a shorter stride length and time, together with longer stance and double-support phases, are associated

  8. Exercises to Improve Gait Abnormalities

    ... Articles Directories Videos Resources Contact Exercises to Improve Gait Abnormalities Home » Article Categories » Exercise and Fitness Font Size: A A A A Exercises to Improve Gait Abnormalities Next Page The manner of how a ...

  9. Temperature dependence of muonium reaction rates in the gas phase

    Fleming, D.G.; Garner, D.M.; Mikula, R.J.; British Columbia Univ., Vancouver

    1981-01-01

    A study of the temperature dependence of reaction rates has long been an important tool in establishing reaction pathways in chemical reactions. This is particularly true for the reactions of muonium (in comparison with those of hydrogen) since a measurement of the activation energy for chemical reaction is sensitive to both the height and the position of the potential barrier in the reaction plane. For collision controlled reactions, on the other hand, the reaction rate is expected to exhibit a weak T 1 sup(/) 2 dependence characteristic of the mean collision velocity. These concepts are discussed and their effects illustrated in a comparison of the chemical and spin exchange reaction rates of muonium and hydrogen in the temperature range approx.300-approx.500 K. (orig.)

  10. Isospin and momentum dependence of liquid-gas phase transition in hot asymmetric nuclear matter

    Xu, Jun; Ma, Hongru; Chen, Liewen; Li, Baoan

    2008-01-01

    The liquid-gas phase transition in hot neutron-rich nuclear matter is investigated within a self-consistent thermal model using different interactions with or without isospin and/or momentum dependence. The boundary of the phase-coexistence region is shown to be sensitive to the density dependence of the nuclear symmetry energy as well as the isospin and momentum dependence of the nuclear interaction. (author)

  11. Gait Analysis of Symptomatic Flatfoot in Children: An Observational Study.

    Kim, Ha Yong; Shin, Hyuck Soo; Ko, Jun Hyuck; Cha, Yong Han; Ahn, Jae Hoon; Hwang, Jae Yeon

    2017-09-01

    Flatfoot deformity is a lever arm disease that incurs kinetic inefficiency during gait. The purpose of this study was to measure the degree of kinetic inefficiency by comparing the gait analysis data of a flatfoot group with a normal control group. The patient group consisted of 26 children (21 males and 5 females) with symptomatic flatfoot. They were examined with gait analysis between May 2005 and February 2014. Exclusion criteria were patients with secondary flatfoot caused by neuromuscular disorders, tarsal coalition, vertical talus, or others. Patients' mean age was 9.5 years (range, 7 to 13 years). The gait analysis data of the study group and the normal control group were compared. The mean vertical ground reaction force (GRF) in the push-off phase was 0.99 for the patient group and 1.15 for the control group ( p push-off phase was 0.89 for the patient group and 1.27 for the control group ( p push-off phase was 1.38 for the patient group and 2.52 for the control group ( p push-off phase during gait. Symptomatic flatfeet had a moment inefficiency of 30% and power inefficiency of 45% during gait compared to feet with preserved medial longitudinal arches.

  12. Changes in spatiotemporal gait parameters following intravenous immunoglobulin treatment for chronic inflammatory demyelinating polyneuropathy.

    Vo, Mary L; Chin, Russell L; Miranda, Caroline; Latov, Norman

    2017-10-01

    Gait impairment is a common presenting symptom in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). However, gait parameters have not previously been evaluated in detail as potential independent outcome measures. We prospectively measured changes in spatiotemporal gait parameters of 20 patients with CIDP at baseline and following treatment with intravenous immunoglobulin (IVIG), using GAITRite® a computerized walkway system with embedded sensors. Overall, study patients showed significant improvements in gait velocity, cadence, stride length, double support time, stance phase, and swing phase following IVIG treatment. Mean changes in velocity, stance phase, and swing phase, exhibited the greatest statistical significance among the subgroup that exhibited clinically meaningful improvement in Inflammatory Neuropathy Cause and Treatment disability score, Medical Research Council sum score, and grip strength. Assessment of gait parameters, in particular velocity, step phase and swing phase, is a potentially sensitive outcome measure for evaluating treatment response in CIDP. Muscle Nerve 56: 732-736, 2017. © 2017 Wiley Periodicals, Inc.

  13. Gait adjustments in obstacle crossing, gait initiation and gait termination after a recent lower limb amputation

    Vrieling, Aline H.; van Keeken, Helco G.; Schoppen, Tanneke; Hof, At L.; Otten, Bert; Halbertsma, Jan P. K.; Postema, Klaas

    Objective: To describe the adjustments in gait characteristics of obstacle crossing, gait initiation and gait termination that occur in subjects with a recent lower limb amputation during the rehabilitation process. Design: Prospective and descriptive study. Subjects: Fourteen subjects with a recent

  14. Effect of Cue Timing and Modality on Gait Initiation in Parkinson Disease With Freezing of Gait.

    Lu, Chiahao; Amundsen Huffmaster, Sommer L; Tuite, Paul J; Vachon, Jacqueline M; MacKinnon, Colum D

    2017-07-01

    To examine the effects of cue timing, across 3 sensory modalities, on anticipatory postural adjustments (APAs) during gait initiation in people with Parkinson disease (PD). Observational study. Biomechanics research laboratory. Individuals with idiopathic PD (N=25; 11 with freezing of gait [FOG]) were studied in the off-medication state (12-h overnight withdrawal). Gait initiation was tested without cueing (self-initiated) and with 3 cue timing protocols: fixed delay (3s), random delay (4-12s), and countdown (3-2-1-go, 1-s intervals) across 3 sensory modalities (acoustic, visual, and vibrotactile). The incidence and spatiotemporal characteristics of APAs during gait initiation were analyzed, including vertical ground reaction forces and center of pressure. All cue timings and modalities increased the incidence and amplitude of APAs compared with self-initiated stepping. Acoustic and visual cues, but not vibrotactile stimulation, improved the timing of APAs. Fixed delay or countdown timing protocols were more effective at decreasing APA durations than random delay cues. Cue-evoked improvements in APA timing, but not amplitude, correlated with the level of impairment during self-initiated gait. Cues did not improve the late push-off phase in the FOG group. External cueing improves gait initiation in PD regardless of cue timing, modality, or clinical phenotype (with and without FOG). Acoustic or visual cueing with predictive timing provided the greatest improvements in gait initiation; therefore, these protocols may provide the best outcomes when applied by caregivers or devices. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  15. HYSSOP COMPOSITION DEPENDING ON AGE AND PLANTS DEVELOPMENT PHASES

    L. A. Kotyuk

    2015-10-01

    Full Text Available The aim of the paper is to research biochemical composition of Hyssopus officinalis L. (Lamiaceae in relation to plant age and phenological growth stage under conditions of Ukrainian Polissya, bin order to determine the optimal harvest dates of the herbal material and its application spheres. The raw material samples under analysis were cut at various growth stages: the vegetative, budding, blooming, ripening stages. To study the hyssop oil composition, areal parts of H. officinalis were used. The composition analysis was aimed at determining absolute dry matter (by drying samples at 105 °C up to the constant mass, “crude” cellulose, amounts of protein, fats, calcium, potassium, phosphorus, ascorbic acid, carotene, discernible sugars and tannins and essential oil. The present study has proved that in the plant ontogenesis the amount of essential oil, obtained from H. officinalis areal parts, does not markedly decrease: volatile oil yield in plants of the first, second and third years of life amounted to 1.007%, 0.75% and 0.71% respectively. The composition of volatile oil in the plants of the first year of life reveals 46 components, of which pinocampone (53.73%, isopinocampone (4.66% myrtenol (9.35% and camphor (3.86% prevailed. In H. officinalis volatile oil of the third year 30 components were identified, the prevailing of which were isopinocampone (44.43%, pinocampone (35.49%, myrtenol (5.26%, germacrene D (3.15%, pulegone (2.93% and bicyclogermacrene (1.35%. We could observe the change in the quantitative and qualitative composition of H. officinalis volatile oil throughout the entire vegetation period. Thus, in the phase of vegetative growth one can identify 25 compounds, the most predominant being elemol (33.25%, germacren D (21.59% and bicyclogermacrene (15.78%. In the phase of blossoming 30 components can be identified, a high amount of isopinocampone and pinocampone (44.43% and 35.49% and somewhat lover amount of myrtenol (5

  16. Solid phase epitaxy of amorphous silicon carbide: Ion fluence dependence

    Bae, I.-T.; Ishimaru, Manabu; Hirotsu, Yoshihiko; Sickafus, Kurt E.

    2004-01-01

    We have investigated the effect of radiation damage and impurity concentration on solid phase epitaxial growth of amorphous silicon carbide (SiC) as well as microstructures of recrystallized layer using transmission electron microscopy. Single crystals of 6H-SiC with (0001) orientation were irradiated with 150 keV Xe ions to fluences of 10 15 and 10 16 /cm 2 , followed by annealing at 890 deg. C. Full epitaxial recrystallization took place in a specimen implanted with 10 15 Xe ions, while retardation of recrystallization was observed in a specimen implanted with 10 16 /cm 2 Xe ions. Atomic pair-distribution function analyses and energy dispersive x-ray spectroscopy results suggested that the retardation of recrystallization of the 10 16 Xe/cm 2 implanted sample is attributed to the difference in amorphous structures between the 10 15 and 10 16 Xe/cm 2 implanted samples, i.e., more chemically disordered atomistic structure and higher Xe impurity concentration in the 10 16 Xe/cm 2 implanted sample

  17. Velocity-dependent quantum phase slips in 1D atomic superfluids.

    Tanzi, Luca; Scaffidi Abbate, Simona; Cataldini, Federica; Gori, Lorenzo; Lucioni, Eleonora; Inguscio, Massimo; Modugno, Giovanni; D'Errico, Chiara

    2016-05-18

    Quantum phase slips are the primary excitations in one-dimensional superfluids and superconductors at low temperatures but their existence in ultracold quantum gases has not been demonstrated yet. We now study experimentally the nucleation rate of phase slips in one-dimensional superfluids realized with ultracold quantum gases, flowing along a periodic potential. We observe a crossover between a regime of temperature-dependent dissipation at small velocity and interaction and a second regime of velocity-dependent dissipation at larger velocity and interaction. This behavior is consistent with the predicted crossover from thermally-assisted quantum phase slips to purely quantum phase slips.

  18. Effects of progressive backward body weight suppoted treadmill training on gait ability in chronic stroke patients: A randomized controlled trial.

    Kim, Kyung Hun; Lee, Kyoung Bo; Bae, Young-Hyeon; Fong, Shirley S M; Lee, Suk Min

    2017-10-23

    A stroke patient with hemiplegic gait is generally described as being slow and asymmetric. Body weight-supported treadmill training and backward gait training are recent additions to therapeutic gait trainings that may help improve gait in stroke patient with hemiplegic gait. Therefore, we examined the effect of progressive backward body weight-supported treadmill training on gait in chronic stroke patients with hemiplegic gait. Thirty subjects were divided to the experimental and control groups. The experimental group consisted of 15 patients and underwent progressive backward body weight-supported treadmill training. The control group consisted of 15 patients and underwent general treadmill gait training five times per week, for a total of four weeks. The OptoGait was used to analyze gait kinematics, and the dynamic gait index (DGI) and results of the 6-minute walk test were used as the clinical evaluation indicators. A follow-up test was carried out four weeks later to examine persistence of exercise effects. The experimental group showed statistically significant results in all dependent variables week four compared to the control group. However, until the eighth week, only the dependent variables, of affected step length (ASL), stride length (SL), and DGI differed significantly between the two groups. This study verified that progressive bodyweight-supported treadmill training had a positive influence on the temporospatial characteristics of gait and clinical gait evaluation index in chronic stroke patients.

  19. Intra-individual gait pattern variability in specific situations: Implications for forensic gait analysis.

    Ludwig, Oliver; Dillinger, Steffen; Marschall, Franz

    2016-07-01

    In this study, inter- and intra-individual gait pattern differences are examined in various gait situations by means of phase diagrams of the extremity angles (cyclograms). 8 test subjects walked along a walking distance of 6m under different conditions three times each: barefoot, wearing sneakers, wearing combat boots, after muscular fatigue, and wearing a full-face motorcycle helmet restricting vision. The joint angles of foot, knee, and hip were recorded in the sagittal plane. The coupling of movements was represented by time-adjusted cyclograms, and the inter- and intra-individual differences were captured by calculating the similarity between different gait patterns. Gait pattern variability was often greater between the defined test situations than between the individual test subjects. The results have been interpreted considering neurophysiological regulation mechanisms. Footwear, masking, and fatigue were interpreted as disturbance parameters, each being a cause for gait pattern variability and complicating the inference of identity of persons in video recordings. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  20. Exoskeleton-assisted gait training to improve gait in individuals with spinal cord injury: a pilot randomized study.

    Chang, Shuo-Hsiu; Afzal, Taimoor; Berliner, Jeffrey; Francisco, Gerard E

    2018-01-01

    Robotic wearable exoskeletons have been utilized as a gait training device in persons with spinal cord injury. This pilot study investigated the feasibility of offering exoskeleton-assisted gait training (EGT) on gait in individuals with incomplete spinal cord injury (iSCI) in preparation for a phase III RCT. The objective was to assess treatment reliability and potential efficacy of EGT and conventional physical therapy (CPT). Forty-four individuals were screened, and 13 were eligible to participate in the study. Nine participants consented and were randomly assigned to receive either EGT or CPT with focus on gait. Subjects received EGT or CPT, five sessions a week (1 h/session daily) for 3 weeks. American Spinal Injury Association (ASIA) Lower Extremity Motor Score (LEMS), 10-Meter Walk Test (10MWT), 6-Minute Walk Test (6MWT), Timed Up and Go (TUG) test, and gait characteristics including stride and step length, cadence and stance, and swing phase durations were assessed at the pre- and immediate post- training. Mean difference estimates with 95% confidence intervals were used to analyze the differences. After training, improvement was observed in the 6MWT for the EGT group. The CPT group showed significant improvement in the TUG test. Both the EGT and the CPT groups showed significant increase in the right step length. EGT group also showed improvement in the stride length. EGT could be applied to individuals with iSCI to facilitate gait recovery. The subjects were able to tolerate the treatment; however, exoskeleton size range may be a limiting factor in recruiting larger cohort of patients. Future studies with larger sample size are needed to investigate the effectiveness and efficacy of exoskeleton-assisted gait training as single gait training and combined with other gait training strategies. Clinicaltrials.org, NCT03011099, retrospectively registered on January 3, 2017.

  1. Preliminary Assessment of a Compliant Gait Exoskeleton.

    Cestari, Manuel; Sanz-Merodio, Daniel; Garcia, Elena

    2017-06-01

    Current commercial wearable gait exoskeletons contain joints with stiff actuators that cannot adapt to unpredictable environments. These actuators consume a significant amount of energy, and their stiffness may not be appropriate for safe human-machine interactions. Adjustable compliant actuators are being designed and implemented because of their ability to minimize large forces due to shocks, to safely interact with the user, and to store and release energy in passive elastic elements. Introduction of such compliant actuation in gait exoskeletons, however, has been limited by the larger power-to-weight and volume ratio requirement. This article presents a preliminary assessment of the first compliant exoskeleton for children. Compliant actuation systems developed by our research group were integrated into the ATLAS exoskeleton prototype. The resulting device is a compliant exoskeleton, the ATLAS-C prototype. The exoskeleton is coupled with a special standing frame to provide balance while allowing a semi-natural gait. Experiments show that when comparing the behavior of the joints under different stiffness conditions, the inherent compliance of the implemented actuators showed natural adaptability during the gait cycle and in regions of shock absorption. Torque tracking of the joint is achieved, identifying the areas of loading response. The implementation of a state machine in the control of knee motion allowed reutilization of the stored energy during deflection at the end of the support phase to partially propel the leg and achieve a more natural and free swing.

  2. Can biomechanical variables predict improvement in crouch gait?

    Hicks, Jennifer L.; Delp, Scott L.; Schwartz, Michael H.

    2011-01-01

    Many patients respond positively to treatments for crouch gait, yet surgical outcomes are inconsistent and unpredictable. In this study, we developed a multivariable regression model to determine if biomechanical variables and other subject characteristics measured during a physical exam and gait analysis can predict which subjects with crouch gait will demonstrate improved knee kinematics on a follow-up gait analysis. We formulated the model and tested its performance by retrospectively analyzing 353 limbs of subjects who walked with crouch gait. The regression model was able to predict which subjects would demonstrate ‘improved’ and ‘unimproved’ knee kinematics with over 70% accuracy, and was able to explain approximately 49% of the variance in subjects’ change in knee flexion between gait analyses. We found that improvement in stance phase knee flexion was positively associated with three variables that were drawn from knowledge about the biomechanical contributors to crouch gait: i) adequate hamstrings lengths and velocities, possibly achieved via hamstrings lengthening surgery, ii) normal tibial torsion, possibly achieved via tibial derotation osteotomy, and iii) sufficient muscle strength. PMID:21616666

  3. Film thickness dependence of phase separation and dewetting behaviors in PMMA/SAN blend films.

    You, Jichun; Liao, Yonggui; Men, Yongfeng; Shi, Tongfei; An, Lijia

    2010-09-21

    Film thickness dependence of complex behaviors coupled by phase separation and dewetting in blend [poly(methyl methacrylate) (PMMA) and poly(styrene-ran-acrylonitrile) (SAN)] films on silicon oxide substrate at 175 °C was investigated by grazing incidence ultrasmall-angle X-ray scattering (GIUSAX) and in situ atomic force microscopy (AFM). It was found that the dewetting pathway was under the control of the parameter U(q0)/E, which described the initial amplitude of the surface undulation and original thickness of film, respectively. Furthermore, our results showed that interplay between phase separation and dewetting depended crucially on film thickness. Three mechanisms including dewetting-phase separation/wetting, dewetting/wetting-phase separation, and phase separation/wetting-pseudodewetting were discussed in detail. In conclusion, it is relative rates of phase separation and dewetting that dominate the interplay between them.

  4. Functional Neuroanatomy for Posture and Gait Control

    Kaoru Takakusaki

    2017-01-01

    Full Text Available Here we argue functional neuroanatomy for posture- gait control. Multi-sensory information such as somatosensory, visual and vestibular sensation act on various areas of the brain so that adaptable posture- gait control can be achieved. Automatic process of gait, which is steady-state stepping movements associating with postural reflexes including headeye coordination accompanied by appropriate alignment of body segments and optimal level of postural muscle tone, is mediated by the descending pathways from the brainstem to the spinal cord. Particularly, reticulospinal pathways arising from the lateral part of the mesopontine tegmentum and spinal locomotor network contribute to this process. On the other hand, walking in unfamiliar circumstance requires cognitive process of postural control, which depends on knowledges of self-body, such as body schema and body motion in space. The cognitive information is produced at the temporoparietal association cortex, and is fundamental to sustention of vertical posture and construction of motor programs. The programs in the motor cortical areas run to execute anticipatory postural adjustment that is optimal for achievement of goal-directed movements. The basal ganglia and cerebellum may affect both the automatic and cognitive processes of posturegait control through reciprocal connections with the brainstem and cerebral cortex, respectively. Consequently, impairments in cognitive function by damages in the cerebral cortex, basal ganglia and cerebellum may disturb posture-gait control, resulting in falling.

  5. Modification of hemiplegic compensatory gait pattern by symmetry-based motion controller of HAL.

    Kawamoto, Hiroaki; Kadone, Hideki; Sakurai, Takeru; Sankai, Yoshiyuki

    2015-01-01

    As one of several characteristics of hemiplegic patients after stroke, compensatory gait caused by affected limb is often seen. The purpose of this research is to apply a symmetry-based controller of a wearable type lower limb robot, Hybrid Assistive Limb (HAL) to hemiplegic patients with compensatory gait, and to investigate improvement of gait symmetry. The controller is designed respectively for swing phase and support phase according to characteristics of hemiplegic gait pattern. The controller during swing phase stores the motion of the unaffected limb and then provides motion support on the affected limb during the subsequent swing using the stored pattern to realize symmetric gait based on spontaneous limb swing. Moreover, the controller during support phase provides motion to extend hip and knee joints to support wearer's body. Clinical tests were conducted in order to assess the modification of gait symmetry. Our case study involved participation of one chronic stroke patient who performs abnormally-compensatory gait for both of the affected and unaffected limbs. As a result, the patient's gait symmetry was improved by providing motion support during the swing phase on the affected side and motion constraint during the support phase on the unaffected side. The study showed promising basis for the effectiveness of the controller for the future clinical study.

  6. Auditive Discrimination of Equine Gaits by Parade Horses

    Duilio Cruz-Becerra

    2009-06-01

    Full Text Available The purpose of this study was to examine parade horses’ auditory discriminationamong four types of equine gaits: paso-fino (“fine step”, trote-reunido(“two-beat trot”, trocha (“trot”, and galope-reunido (“gallop”. Two experimentallynaïve horses were trained to discriminate the sound of their owngait (paso-fino or fine step, through an experimental module that dispensedfood if the subject pressed a lever after hearing a sound reproduction of aparticular gait. Three experimental phases were developed, defined by theperiod of exposure to the sounds (20, 10, and 5 seconds, respectively. Thechoice between pairs of sounds including the horse’s own gait (fine stepand two-beat trot; fine step and gallop; and fine step and trot was reinforceddifferentially. The results indicate that the fine step horses are able todiscriminate their own gait from others, and that receptivity to their ownsounds could be included in their training regime.

  7. Adaptive changes in spatiotemporal gait characteristics in women during pregnancy.

    Błaszczyk, Janusz W; Opala-Berdzik, Agnieszka; Plewa, Michał

    2016-01-01

    Spatiotemporal gait cycle characteristics were assessed at early (P1), and late (P2) pregnancy, as well as at 2 months (PP1) and 6 months (PP2) postpartum. A substantial decrease in walking speed was observed throughout the pregnancy, with the slowest speed (1±0.2m/s) being during the third trimester. Walking at slower velocity resulted in complex adaptive adjustments to their spatiotemporal gait pattern, including a shorter step length and an increased duration of both their stance and double-support phases. Duration of the swing phase remained the least susceptible to changes. Habitual walking velocity (1.13±0.2m/s) and the optimal gait pattern were fully recovered 6 months after childbirth. Documented here adaptive changes in the preferred gait pattern seem to result mainly from the altered body anthropometry leading to temporary balance impairments. All the observed changes within stride cycle aimed to improve gait safety by focusing on its dynamic stability. The pregnant women preferred to walk at a slower velocity which allowed them to spend more time in double-support compared with their habitual pattern. Such changes provided pregnant women with a safer and more tentative ambulation that reduced the single-support period and, hence, the possibility of instability. As pregnancy progressed a significant increase in stance width and a decrease in step length was observed. Both factors allow also for gait stability improvement. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Artificial Walking Technologies to Improve Gait in Cerebral Palsy: Multichannel Neuromuscular Stimulation.

    Rose, Jessica; Cahill-Rowley, Katelyn; Butler, Erin E

    2017-11-01

    Cerebral palsy (CP) is the most common childhood motor disability and often results in debilitating walking abnormalities, such as flexed-knee and stiff-knee gait. Current medical and surgical treatments are only partially effective in improving gait abnormalities and may cause significant muscle weakness. However, emerging artificial walking technologies, such as step-initiated, multichannel neuromuscular electrical stimulation (NMES), can substantially improve gait patterns and promote muscle strength in children with spastic CP. NMES may also be applied to specific lumbar-sacral sensory roots to reduce spasticity. Development of tablet computer-based multichannel NMES can leverage lightweight, wearable wireless stimulators, advanced control design, and surface electrodes to activate lower-limb muscles. Musculoskeletal models have been used to characterize muscle contributions to unimpaired gait and identify high muscle demands, which can help guide multichannel NMES-assisted gait protocols. In addition, patient-specific NMES-assisted gait protocols based on 3D gait analysis can facilitate the appropriate activation of lower-limb muscles to achieve a more functional gait: stance-phase hip and knee extension and swing-phase sequence of hip and knee flexion followed by rapid knee extension. NMES-assisted gait treatment can be conducted as either clinic-based or home-based programs. Rigorous testing of multichannel NMES-assisted gait training protocols will determine optimal treatment dosage for future clinical trials. Evidence-based outcome evaluation using 3D kinematics or temporal-spatial gait parameters will help determine immediate neuroprosthetic effects and longer term neurotherapeutic effects of step-initiated, multichannel NMES-assisted gait in children with spastic CP. Multichannel NMES is a promising assistive technology to help children with spastic CP achieve a more upright, functional gait. © 2017 International Center for Artificial Organs and

  9. Size and temperature dependent stability and phase transformation in single-crystal zirconium nanowire

    Sutrakar, Vijay Kumar; Roy Mahapatra, D.

    2011-01-01

    A novel size dependent FCC (face-centered-cubic) → HCP (hexagonally-closed-pack) phase transformation and stability of an initial FCC zirconium nanowire are studied. FCC zirconium nanowires with cross-sectional dimensions 20 Å, in which surface stresses are not enough to drive the phase transformation, show meta-stability. In such a case, an external kinetic energy in the form of thermal heating is required to overcome the energy barrier and achieve FCC → HCP phase transformation. The FCC-HCP transition pathway is also studied using Nudged Elastic Band (NEB) method, to further confirm the size dependent stability/metastability of Zr nanowires. We also show size dependent critical temperature, which is required for complete phase transformation of a metastable-FCC nanowire.

  10. Pressure-dependence of the phase transitions and thermal expansion in zirconium and hafnium pyrovanadate

    Gallington, Leighanne C.; Hester, Brett R.; Kaplan, Benjamin S. [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332‐0400 (United States); Wilkinson, Angus P., E-mail: angus.wilkinson@chemistry.gatech.edu [School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332‐0400 (United States); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332‐0245 (United States)

    2017-05-15

    Low or negative thermal expansion (NTE) has been previously observed in members of the ZrP{sub 2}O{sub 7} family at temperatures higher than their order-disorder phase transitions. The thermoelastic properties and phase behavior of the low temperature superstructure and high temperature negative thermal expansion phases of ZrV{sub 2}O{sub 7} and HfV{sub 2}O{sub 7} were explored via in situ variable temperature/pressure powder x-ray diffraction measurements. The phase transition temperatures of ZrV{sub 2}O{sub 7} and HfV{sub 2}O{sub 7} exhibited a very strong dependence on pressure (∼700 K GPa), with moderate compression suppressing the formation of their NTE phases below 513 K. Compression also reduced the magnitude of the coefficients of thermal expansion in both the positive and negative thermal expansion phases. Additionally, the high temperature NTE phase of ZrV{sub 2}O{sub 7} was found to be twice as stiff as the low temperature positive thermal expansion superstructure (24 and 12 GPa respectively). - Graphical abstract: The temperature at which ZrV{sub 2}O{sub 7} transforms to a phase displaying negative thermal expansion is strongly pressure dependent. The high temperature form of ZrV{sub 2}O{sub 7} is elastically stiffer than the low temperature form. - Highlights: • The order-disorder phase transition temperatures in ZrV{sub 2}O{sub 7} and HfV{sub 2}O{sub 7} are strongly pressure dependent (∼700 K.GPa). • The high temperature (disordered) phase of ZrV{sub 2}O{sub 7} is much stiffer than the ambient temperature (ordered) phase. • Compression reduces the magnitude of the negative thermal expansion in the high temperature phase of ZrV{sub 2}O{sub 7}.

  11. Advanced Prosthetic Gait Training Tool

    2015-12-01

    modules to train individuals to distinguish gait deviations (trunk motion and lower-limb motion). Each of these modules help trainers improve their...AWARD NUMBER: W81XWH-10-1-0870 TITLE: Advanced Prosthetic Gait Training Tool PRINCIPAL INVESTIGATOR: Dr. Karim Abdel-Malek CONTRACTING...study is to produce a computer-based Advanced Prosthetic Gait Training Tool to aid in the training of clinicians at military treatment facilities

  12. Regularization dependence on phase diagram in Nambu–Jona-Lasinio model

    Kohyama, H.; Kimura, D.; Inagaki, T.

    2015-01-01

    We study the regularization dependence on meson properties and the phase diagram of quark matter by using the two flavor Nambu–Jona-Lasinio model. The model also has the parameter dependence in each regularization, so we explicitly give the model parameters for some sets of the input observables, then investigate its effect on the phase diagram. We find that the location or the existence of the critical end point highly depends on the regularization methods and the model parameters. Then we think that regularization and parameters are carefully considered when one investigates the QCD critical end point in the effective model studies

  13. Study of critical dependence of stable phases in Nitinol on heat treatment using electrical resistivity probe

    Uchil, J.; Mohanchandra, K.P.; Kumara, K.G.; Mahesh, K.K.

    1998-01-01

    Phase transformations in 40% cold-worked Nitinol as a function of heat treatment have been studied using electrical resistivity variation with temperature. The stabilisation of austenitic, rhombohedral and martensitic phases is shown to critically depend on the temperatures of heat treatment by the analysis of temperature dependence of electrical resistivity in heating and cooling parts of the cycle. Characteristic values of electrical resistivity of the stable phases are determined. The R-phase has been found to form continuously with increasing heat-treatment temperature starting from room temperature and to suddenly disappear beyond heat-treatment at 683 K. The observed presence or absence of R-phase is confirmed by heat capacity measurements as a function of temperature. (orig.)

  14. Sex differences in quadrupedal walking gaits of Uner Tan syndrome cases, healthy humans and nonhuman primates.

    Tan, Uner

    2017-03-01

    Uner Tan syndrome (UTS) cases with habitual quadrupedal locomotion (QL), impaired intelligence, and dysarthric or no speech predominantly use lateral sequence (LS) gait like nonprimates rather than the predominantly diagonal sequence (DS) gait of nonhuman primates. However, these studies neglected possible sex-related differences in these gait types. (1) To assess the possible sex-related gait types in UTS cases, healthy infants and adults with requested QL, and the nonhuman primates. (2) To test the hypothesis that sex differences may exist in quadrupedal walking gaits in UTS cases, healthy humans, and nonhuman primates. The UTS cases were filmed, the other study groups were taken from public open 'youtube' videos, which were used to assess the walking gait types as DS and LS. The right and left hind-limb phase values were calculated separately for males and females to allow a possible sex difference in walking gaits to be determined. Females predominantly used DS gait, contrary to males with predominantly LS gait. Consistent with the working hypothesis, the results suggested a biological sex-related trend in preferred walking gaits exists in all of the human and nonhuman primates using QL.

  15. Time-dependent Hartree-Fock dynamics and phase transition in Lipkin-Meshkov-Glick model

    Kan, K.; Lichtner, P.C.; Dworzecka, M.; Griffin, J.J.

    1980-01-01

    The time-dependent Hartree-Fock solutions of the two-level Lipkin-Meshkov-Glick model are studied by transforming the time-dependent Hartree-Fock equations into Hamilton's canonical form and analyzing the qualitative structure of the Hartree-Fock energy surface in the phase space. It is shown that as the interaction strength increases these time-dependent Hartree-Fock solutions undergo a qualitative change associated with the ground state phase transition previously studied in terms of coherent states. For two-body interactions stronger than the critical value, two types of time-dependent Hartree-Fock solutions (the ''librations'' and ''rotations'' in Hamilton's mechanics) exist simultaneously, while for weaker interactions only the rotations persist. It is also shown that the coherent states with the maximum total pseudospin value are determinants, so that time-dependent Hartree-Fock analysis is equivalent to the coherent state method

  16. Competing failure analysis in phased-mission systems with multiple functional dependence groups

    Wang, Chaonan; Xing, Liudong; Peng, Rui; Pan, Zhusheng

    2017-01-01

    A phased-mission system (PMS) involves multiple, consecutive, non-overlapping phases of operation. The system structure function and component failure behavior in a PMS can change from phase to phase, posing big challenges to the system reliability analysis. Further complicating the problem is the functional dependence (FDEP) behavior where the failure of certain component(s) causes other component(s) to become unusable or inaccessible or isolated. Previous studies have shown that FDEP can cause competitions between failure propagation and failure isolation in the time domain. While such competing failure effects have been well addressed in single-phase systems, only little work has focused on PMSs with a restrictive assumption that a single FDEP group exists in one phase of the mission. Many practical systems (e.g., computer systems and networks), however may involve multiple FDEP groups during the mission. Moreover, different FDEP groups can be dependent due to sharing some common components; they may appear in a single phase or multiple phases. This paper makes new contributions by modeling and analyzing reliability of PMSs subject to multiple FDEP groups through a Markov chain-based methodology. Propagated failures with both global and selective effects are considered. Four case studies are presented to demonstrate application of the proposed method. - Highlights: • Reliability of phased-mission systems subject to competing failure propagation and isolation effects is modeled. • Multiple independent or dependent functional dependence groups are considered. • Propagated failures with global effects and selective effects are studied. • Four case studies demonstrate generality and application of the proposed Markov-based method.

  17. An Ambulatory System for Gait Monitoring Based on Wireless Sensorized Insoles

    González, Iván; Fontecha, Jesús; Hervás, Ramón; Bravo, José

    2015-01-01

    A new gait phase detection system for continuous monitoring based on wireless sensorized insoles is presented. The system can be used in gait analysis mobile applications, and it is designed for real-time demarcation of gait phases. The system employs pressure sensors to assess the force exerted by each foot during walking. A fuzzy rule-based inference algorithm is implemented on a smartphone and used to detect each of the gait phases based on the sensor signals. Additionally, to provide a solution that is insensitive to perturbations caused by non-walking activities, a probabilistic classifier is employed to discriminate walking forward from other low-level activities, such as turning, walking backwards, lateral walking, etc. The combination of these two algorithms constitutes the first approach towards a continuous gait assessment system, by means of the avoidance of non-walking influences. PMID:26184199

  18. An Ambulatory System for Gait Monitoring Based on Wireless Sensorized Insoles

    Iván González

    2015-07-01

    Full Text Available A new gait phase detection system for continuous monitoring based on wireless sensorized insoles is presented. The system can be used in gait analysis mobile applications, and it is designed for real-time demarcation of gait phases. The system employs pressure sensors to assess the force exerted by each foot during walking. A fuzzy rule-based inference algorithm is implemented on a smartphone and used to detect each of the gait phases based on the sensor signals. Additionally, to provide a solution that is insensitive to perturbations caused by non-walking activities, a probabilistic classifier is employed to discriminate walking forward from other low-level activities, such as turning, walking backwards, lateral walking, etc. The combination of these two algorithms constitutes the first approach towards a continuous gait assessment system, by means of the avoidance of non-walking influences.

  19. Three-Dimensional Trunk and Lower Limbs Characteristics during Gait in Patients with Huntington's Disease.

    Mirek, Elzbieta; Filip, Magdalena; Chwała, Wiesław; Banaszkiewicz, Krzysztof; Rudzinska-Bar, Monika; Szymura, Jadwiga; Pasiut, Szymon; Szczudlik, Andrzej

    2017-01-01

    Objective: A number of studies on gait disturbances have been conducted, however, no clear pattern of gait disorders was described. The aim of the study was to characterize the gait pattern in HD patients by conducting analysis of mean angular movement changes the lower limb joints and trunk (kinematics parameters). Methods: The study group consisted of 30 patients with HD (17 women and 13 men). The reference data include the results of 30 healthy subjects (17 women and 13 men). Registration of gait with the Vicon 250 system was performed using passive markers attached to specific anthropometric points directly on the skin, based on the Golem biomechanical model (Oxford Metrics Ltd.). The research group and the control group were tested once. Results: Statistically significant ( p patients were observed in: insufficient plantar flexion during Loading Response and Pre-swing phases; insufficient flexion of the knee joint during Initial Swing and Mid Swing phases; excessive flexion of the hip in Terminal Stance and Pre-swing phases and over-normative forward inclination of the trunk in all gait phases. It should be noted that the group of patients with HD obtained, for all the mean angular movement changes higher standard deviation. Conclusion: A characteristic gait disorder common to all patients with HD occurring throughout the whole duration of the gait cycle is a pathological anterior tilt of the trunk. The results will significantly contribute to programming physiotherapy for people with HD, aimed at stabilizing the trunk in a position of extension during gait.

  20. Age-related decline of gait variability in children with attention-deficit/hyperactivity disorder: Support for the maturational delay hypothesis in gait.

    Manicolo, Olivia; Grob, Alexander; Lemola, Sakari; Hagmann-von Arx, Priska

    2016-02-01

    Previous findings showed a tendency toward higher gait variability in children with attention-deficit/hyperactivity disorder (ADHD) compared to controls. This study examined whether gait variability in children with ADHD eventually approaches normality with increasing age (delay hypothesis) or whether these gait alterations represent a persistent deviation from typical development (deviation hypothesis). This cross-sectional study compared 30 children with ADHD (25 boys; Mage=10 years 11 months, range 8-13 years; n=21 off medication, n=9 without medication) to 28 controls (25 boys; Mage=10 years 10 months, range 8-13 years). Gait parameters (i.e. velocity and variability in stride length and stride time) were assessed using an electronic walkway system (GAITRite) while children walked at their own pace. Children with ADHD walked with significantly higher variability in stride time compared to controls. Age was negatively associated with gait variability in children with ADHD such that children with higher age walked with lower variability, whereas in controls there was no such association. Children with ADHD displayed a less regular gait pattern than controls, indicated by their higher variability in stride time. The age-dependent decrease of gait variability in children with ADHD showed that gait performance became more regular with age and converged toward that of typically developing children. These results may reflect a maturational delay rather than a persistent deviation of gait regularity among children with ADHD compared to typically developing children. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Quantitative analysis of gait in the visually impaired.

    Nakamura, T

    1997-05-01

    In this comparative study concerning characteristics of independent walking by visually impaired persons, we used a motion analyser system to perform gait analysis of 15 late blind (age 36-54, mean 44.3 years), 15 congenitally blind (age 39-48, mean 43.8 years) and 15 sighted persons (age 40-50, mean 44.4 years) while walking a 10-m walkway. All subjects were male. Compared to the sighted, late blind and congenitally blind persons had a significantly slower walking speed, shorter stride length and longer time in the stance phase of gait. However, the relationships between gait parameters in the late and congenitally blind groups were maintained, as in the sighted group. In addition, the gait of the late blind showed a tendency to approximate the gait patterns of the congenitally blind as the duration of visual loss progressed. Based on these results we concluded that the gait of visually impaired persons, through its active use of non-visual sensory input, represents an attempt to adapt to various environmental conditions in order to maintain a more stable posture and to effect safe walking.

  2. Gait Deviations in Children with Autism Spectrum Disorders: A Review

    Deirdre Kindregan

    2015-01-01

    Full Text Available In recent years, it has become clear that children with autism spectrum disorders (ASDs have difficulty with gross motor function and coordination, factors which influence gait. Knowledge of gait abnormalities may be useful for assessment and treatment planning. This paper reviews the literature assessing gait deviations in children with ASD. Five online databases were searched using keywords “gait” and “autism,” and 11 studies were found which examined gait in childhood ASD. Children with ASD tend to augment their walking stability with a reduced stride length, increased step width and therefore wider base of support, and increased time in the stance phase. Children with ASD have reduced range of motion at the ankle and knee during gait, with increased hip flexion. Decreased peak hip flexor and ankle plantar flexor moments in children with ASD may imply weakness around these joints, which is further exhibited by a reduction in ground reaction forces at toe-off in children with ASD. Children with ASD have altered gait patterns to healthy controls, widened base of support, and reduced range of motion. Several studies refer to cerebellar and basal ganglia involvement as the patterns described suggest alterations in those areas of the brain. Further research should compare children with ASD to other clinical groups to improve assessment and treatment planning.

  3. Tic-induced gait dysfunction.

    Fasano, A.; Ruzicka, E.; Bloem, B.R.

    2012-01-01

    BACKGROUND: Many neurological disorders impair gait, but only a few of them are episodic or paroxysmal, the most important ones being freezing of gait and paroxysmal dyskinesias. METHODS: We describe 4 patients with tic disorders (3 with Tourette syndrome, and 1 with a tic disorder secondary to

  4. Gait analysis in forensic medicine

    Larsen, Peter K; Simonsen, Erik B; Lynnerup, Niels

    2008-01-01

    Recordings from video surveillance systems are used as evidence from crime scenes. It would be useful to perform comparisons between disguised perpetrators and suspects based on their gait. We applied functional anatomical and biomechanical knowledge to analyze the gait of perpetrators, as record...

  5. Constant resolution of time-dependent Hartree--Fock phase ambiguity

    Lichtner, P.C.; Griffin, J.J.; Schultheis, H.; Schultheis, R.; Volkov, A.B.

    1978-01-01

    The customary time-dependent Hartree--Fock problem is shown to be ambiguous up to an arbitrary function of time additive to H/sub HF/, and, consequently, up to an arbitrary time-dependent phase for the solution, PHI(t). The ''constant'' (H)'' phase is proposed as the best resolution of this ambiguity. It leads to the following attractive features: (a) the time-dependent Hartree--Fock (TDHF) Hamiltonian, H/sub HF/, becomes a quantity whose expectation value is equal to the average energy and, hence, constant in time; (b) eigenstates described exactly by determinants, have time-dependent Hartree--Fock solutions identical with the exact time-dependent solutions; (c) among all possible TDHF solutions this choice minimizes the norm of the quantity (H--i dirac constant delta/delta t) operating on the ket PHI, and guarantees optimal time evolution over an infinitesimal period; (d) this choice corresponds both to the stationary value of the absolute difference between (H) and (i dirac constant delta/delta t) and simultaneously to its absolute minimal value with respect to choice of the time-dependent phase. The source of the ambiguity is discussed. It lies in the time-dependent generalization of the freedom to transform unitarily among the single-particle states of a determinant at the (physically irrelevant for stationary states) cost of altering only a factor of unit magnitude

  6. Evaluation of gait performance of knee osteoarthritis patients after total knee arthroplasty with different assistive devices

    Ana Tereso

    Full Text Available IntroductionNowadays Knee Osteoarthritis (KOA affects a large percentage of the elderly, and one solution is to perform a Total Knee Arthroplasty (TKA. In this paper, one intends to study the gait and posture of these patients after the TKA, while walking with three assistive devices (ADs (crutches, standard walker (SW and rollator with forearm supports (RFS.MethodsEleven patients were evaluated in 2 phases: 5 days and 15 days after surgery. This evaluation was conducted with two inertial sensors, one attached to the operated leg ankle, to measure spatiotemporal parameters, and the other at the sacrum, to measure posture and fall risk-related parameters. Multivariate analysis of variance (MANOVA with repeated measures was performed to detect group differences.ResultsThe MANOVA results show that all spatiotemporal parameters are significantly different (p0.05. The interaction between time and ADs only affects significantly the velocity (p<0.05. In terms of fall risk parameters, time only significantly affects the antero-posterior direction (p<0.05 and ADs affects significantly root mean square in medio-lateral direction (p<0.05. In terms of interaction between time and ADs, there are no statistical significant differences.ConclusionThis study concludes that depending on the state of recovery of the patient, different ADs should be prescribed. On the overall, standard walker is good to give stability to the patient and RFS allows the patient to present a gait pattern closer to a natural gait.

  7. The effects of high custom made shoes on gait characteristics and patient satisfaction in hemiplegic gait.

    Eckhardt, Martine M; Mulder, Mascha C Borgerhoff; Horemans, Herwin L; van der Woude, Luc H; Ribbers, Gerard M

    2011-10-01

    To determine the effects of a temporary high custom made orthopaedic shoe on functional mobility, walking speed, and gait characteristics in hemiplegic stroke patients. In addition, interference of attentional demands and patient satisfaction were studied. Clinical experimental study. University Medical Centre. Nineteen stroke patients (12 males; mean age 55 years (standard deviation (SD) 10 years); mean time post onset 3.6 months (SD 1.4 months)) with a spastic paresis of the lower extremity. Functional mobility was assessed with the timed up and go test, walking speed and gait characteristics were measured with clinical gait analysis and performed with and without a verbal dual task. Patient satisfaction was determined with a questionnaire. Walking with the high orthopaedic shoe resulted in improved functional mobility (22%; pshoes. The dual task interfered with functional mobility during walking. The interference was equally big for normal shoes as for the orthopaedic shoe. Patients evaluated walking with the high orthopaedic shoe as an improvement (psafety, walking distance and walking speed. In the early recovery phase after stroke, when regaining walking ability, a temporary high orthopaedic shoe can improve hemiplegic gait, even with dual task interference. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Time-dependent weak values and their intrinsic phases of evolution

    Parks, A D

    2008-01-01

    The equation of motion for a time-dependent weak value of a quantum-mechanical observable is known to contain a complex valued energy factor (the weak energy of evolution) that is defined by the dynamics of the pre-selected and post-selected states which specify the observable's weak value. In this paper, the mechanism responsible for the creation of this energy is identified and it is shown that the cumulative effect over time of this energy is manifested as dynamical phases and pure geometric phases (the intrinsic phases of evolution) which govern the evolution of the weak value during its measurement process. These phases are simply related to a Pancharatnam phase and Fubini-Study metric distance defined by the Hilbert space evolution of the associated pre-selected and post-selected states. A characterization of time-dependent weak value evolution as Pancharatnam phase angle rotations and Fubini-Study distance scalings of a vector in the Argand plane is discussed as an application of this relationship. The theory of weak values is also reviewed and simple 'gedanken experiments' are used to illustrate both the time-independent and the time-dependent versions of the theory. It is noted that the direct experimental observation of the weak energy of evolution would strongly support the time-symmetric paradigm of quantum mechanics and it is suggested that weak value equations of motion represent a new category of nonlocal equations of motion

  9. Absence of phase-dependent noise in time-domain reflectivity studies of impulsively excited phonons

    Hussain, A.

    2010-06-17

    There have been several reports of phase-dependent noise in time-domain reflectivity studies of optical phonons excited by femtosecond laser pulses in semiconductors, semimetals, and superconductors. It was suggested that such behavior is associated with the creation of squeezed phonon states although there is no theoretical model that directly supports such a proposal. We have experimentally re-examined the studies of phonons in bismuth and gallium arsenide, and find no evidence of any phase-dependent noise signature associated with the phonons. We place an upper limit on any such noise at least 40–50 dB lower than previously reported.

  10. Phase-Space Manipulation of Ultracold Ion Bunches with Time-Dependent Fields

    Reijnders, M. P.; Debernardi, N.; Geer, S. B. van der; Mutsaers, P. H. A.; Vredenbregt, E. J. D.; Luiten, O. J.

    2010-01-01

    All applications of high brightness ion beams depend on the possibility to precisely manipulate the trajectories of the ions or, more generally, to control their phase-space distribution. We show that the combination of a laser-cooled ion source and time-dependent acceleration fields gives new possibilities to perform precise phase-space control. We demonstrate reduction of the longitudinal energy spread and realization of a lens with control over its focal length and sign, as well as the sign of the spherical aberrations. This creates new possibilities to correct for the spherical and chromatic aberrations which are presently limiting the spatial resolution.

  11. Absence of phase-dependent noise in time-domain reflectivity studies of impulsively excited phonons

    Hussain, A.; Andrews, S. R.

    2010-01-01

    There have been several reports of phase-dependent noise in time-domain reflectivity studies of optical phonons excited by femtosecond laser pulses in semiconductors, semimetals, and superconductors. It was suggested that such behavior is associated with the creation of squeezed phonon states although there is no theoretical model that directly supports such a proposal. We have experimentally re-examined the studies of phonons in bismuth and gallium arsenide, and find no evidence of any phase-dependent noise signature associated with the phonons. We place an upper limit on any such noise at least 40–50 dB lower than previously reported.

  12. Gait Complexity and Regularity Are Differently Modulated by Treadmill Walking in Parkinson's Disease and Healthy Population

    Thibault Warlop

    2018-02-01

    Full Text Available Variability raises considerable interest as a promising and sensitive marker of dysfunction in physiology, in particular in neurosciences. Both internally (e.g., pathology and/or externally (e.g., environment generated perturbations and the neuro-mechanical responses to them contribute to the fluctuating dynamics of locomotion. Defective internal gait control in Parkinson's disease (PD, resulting in typical timing gait disorders, is characterized by the breakdown of the temporal organization of stride duration variability. Influence of external cue on gait pattern could be detrimental or advantageous depending on situations (healthy or pathological gait pattern, respectively. As well as being an interesting rehabilitative approach in PD, treadmills are usually implemented in laboratory settings to perform instrumented gait analysis including gait variability assessment. However, possibly acting as an external pacemaker, treadmill could modulate the temporal organization of gait variability of PD patients which could invalidate any gait variability assessment. This study aimed to investigate the immediate influence of treadmill walking (TW on the temporal organization of stride duration variability in PD and healthy population. Here, we analyzed the gait pattern of 20 PD patients and 15 healthy age-matched subjects walking on overground and on a motorized-treadmill (randomized order at a self-selected speed. The temporal organization and regularity of time series of walking were assessed on 512 consecutive strides and assessed by the application of non-linear mathematical methods (i.e., the detrended fluctuation analysis and power spectral density; and sample entropy, for the temporal organization and regularity of gait variability, respectively. A more temporally organized and regular gait pattern seems to emerge from TW in PD while no influence was observed on healthy gait pattern. Treadmill could afford the necessary framework to regulate gait

  13. Energy Expenditure of Trotting Gait Under Different Gait Parameters

    Chen, Xian-Bao; Gao, Feng

    2017-07-01

    Robots driven by batteries are clean, quiet, and can work indoors or in space. However, the battery endurance is a great problem. A new gait parameter design energy saving strategy to extend the working hours of the quadruped robot is proposed. A dynamic model of the robot is established to estimate and analyze the energy expenditures during trotting. Given a trotting speed, optimal stride frequency and stride length can minimize the energy expenditure. However, the relationship between the speed and the optimal gait parameters is nonlinear, which is difficult for practical application. Therefore, a simplified gait parameter design method for energy saving is proposed. A critical trotting speed of the quadruped robot is found and can be used to decide the gait parameters. When the robot is travelling lower than this speed, it is better to keep a constant stride length and change the cycle period. When the robot is travelling higher than this speed, it is better to keep a constant cycle period and change the stride length. Simulations and experiments on the quadruped robot show that by using the proposed gait parameter design approach, the energy expenditure can be reduced by about 54% compared with the 100 mm stride length under 500 mm/s speed. In general, an energy expenditure model based on the gait parameter of the quadruped robot is built and the trotting gait parameters design approach for energy saving is proposed.

  14. Effects of walking speed on asymmetry and bilateral coordination of gait

    Plotnik, Meir; Bartsch, Ronny P.; Zeev, Aviva; Giladi, Nir; Hausdorff, Jeffery M.

    2013-01-01

    The mechanisms regulating the bilateral coordination of gait in humans are largely unknown. Our objective was to study how bilateral coordination changes as a result of gait speed modifications during over ground walking. 15 young adults wore force sensitive insoles that measured vertical forces used to determine the timing of the gait cycle events under three walking conditions (i.e., usual-walking, fast and slow). Ground reaction force impact (GRFI) associated with heel-strikes was also quantified, representing the potential contribution of sensory feedback to the regulation of gait. Gait asymmetry (GA) was quantified based on the differences between right and left swing times and the bilateral coordination of gait was assessed using the phase coordination index (PCI), a metric that quantifies the consistency and accuracy of the anti-phase stepping pattern. GA was preserved in the three different gait speeds. PCI was higher (reduced coordination) in the slow gait condition, compared to usual-walking (3.51% vs. 2.47%, respectively, p=0.002), but was not significantly affected in the fast condition. GRFI values were lower in the slow walking as compared to usual-walking and higher in the fast walking condition (pgait related changes in PCI were not associated with the slowed gait related changes in GRFI. The present findings suggest that left-right anti-phase stepping is similar in normal and fast walking, but altered during slowed walking. This behavior might reflect a relative increase in attention resources required to regulate a slow gait speed, consistent with the possibility that cortical function and supraspinal input influences the bilateral coordination of gait. PMID:23680424

  15. Regulators of cyclin-dependent kinases are crucial for maintaining genome integrity in S phase

    Beck, Halfdan; Nähse, Viola; Larsen, Marie Sofie Yoo

    2010-01-01

    are important negative regulators of CDK1 and -2. Strikingly, WEE1 depletion rapidly induced DNA damage in S phase in newly replicated DNA, which was accompanied by a marked increase in single-stranded DNA. This DNA damage is dependent on CDK1 and -2 as well as the replication proteins MCM2 and CDT1 but not CDC...

  16. Phase-dependent outbreak dynamics of geometrid moth linked to host plant phenology.

    Jepsen, Jane U; Hagen, Snorre B; Karlsen, Stein-Rune; Ims, Rolf A

    2009-12-07

    Climatically driven Moran effects have often been invoked as the most likely cause of regionally synchronized outbreaks of insect herbivores without identifying the exact mechanism. However, the degree of match between host plant and larval phenology is crucial for the growth and survival of many spring-feeding pest insects, suggesting that a phenological match/mismatch-driven Moran effect may act as a synchronizing agent. We analyse the phase-dependent spatial dynamics of defoliation caused by cyclically outbreaking geometrid moths in northern boreal birch forest in Fennoscandia through the most recent massive outbreak (2000-2008). We use satellite-derived time series of the prevalence of moth defoliation and the onset of the growing season for the entire region to investigate the link between the patterns of defoliation and outbreak spread. In addition, we examine whether a phase-dependent coherence in the pattern of spatial synchrony exists between defoliation and onset of the growing season, in order to evaluate if the degree of matching phenology between the moth and their host plant could be the mechanism behind a Moran effect. The strength of regional spatial synchrony in defoliation and the pattern of defoliation spread were both highly phase-dependent. The incipient phase of the outbreak was characterized by high regional synchrony in defoliation and long spread distances, compared with the epidemic and crash phase. Defoliation spread was best described using a two-scale stratified spread model, suggesting that defoliation spread is governed by two processes operating at different spatial scale. The pattern of phase-dependent spatial synchrony was coherent in both defoliation and onset of the growing season. This suggests that the timing of spring phenology plays a role in the large-scale synchronization of birch forest moth outbreaks.

  17. Design of a gait training device for control of pelvic obliquity.

    Pietrusinski, Maciej; Severini, Giacomo; Cajigas, Iahn; Mavroidis, Constantinos; Bonato, Paolo

    2012-01-01

    This paper presents the design and testing of a novel device for the control of pelvic obliquity during gait. The device, called the Robotic Gait Rehabilitation (RGR) Trainer, consists of a single actuator system designed to target secondary gait deviations, such as hip-hiking, affecting the movement of the pelvis. Secondary gait deviations affecting the pelvis are generated in response to primary gait deviations (e.g. limited knee flexion during the swing phase) in stroke survivors and contribute to the overall asymmetrical gait pattern often observed in these patients. The proposed device generates a force field able to affect the obliquity of the pelvis (i.e. the rotation of the pelvis around the anteroposterior axis) by using an impedance controlled single linear actuator acting on a hip orthosis. Tests showed that the RGR Trainer is able to induce changes in pelvic obliquity trajectories (hip-hiking) in healthy subjects. These results suggest that the RGR Trainer is suitable to test the hypothesis that has motivated our efforts toward developing the system, namely that addressing both primary and secondary gait deviations during robotic-assisted gait training may help promote a physiologically-sound gait behavior more effectively than when only primary deviations are addressed.

  18. A study of the passive gait of a compass-like biped robot: Symmetry and chaos

    Goswami, A.; Espiau, B.; Thuilot, B.

    1998-01-01

    The focus of this work is a systematic study of the passive gait of a compass-like planar, biped robot on inclined slopes. The robot is kinematically equivalent to a double pendulum, possessing two kneeless legs with point masses and a third point mass at the hip joint. Three parameters, namely, the ground-slope angle and the normalized mass and length of the robot describe its gait. The authors show that in response to a continuous change in any one of its parameters, the symmetric and steady stable gait of the unpowered robot gradually evolves through a regime of bifurcations characterized by progressively complicated asymmetric gaits, eventually arriving at an apparently chaotic gait where not two steps are identical. The robot can maintain this gait indefinitely. A necessary (but not sufficient) condition for the stability of such gaits is the contraction of the phase-fluid volume. For this frictionless robot, the volume contraction, which the authors compute, is caused by the dissipative effects of the ground-impact model. In the chaotic regime, the fractal dimension of the robot's strange attractor (2.07) compared to its state-space dimension (4) also reveals strong contraction. The authors present a novel graphical technique based on the first return map that compactly captures the entire evolution of the gait, from symmetry to chaos. Additional passive dissipative elements in the robot joint results in a significant improvement in the stability and the versatility of the gait, and provide a rich repertoire for simple controls laws

  19. Energy dependence of a local equivalent potential for RGM phase shifts for 16O + 16O

    Ait-Tahar, S.; Mackintosh, R.S.; Cooper, S.G.; Wada, T.

    1993-01-01

    We have found, using the IP inversion method, the local representation of a potential that in S(l) equivalent to the RGM nonlocal potential of Wada and Horiuchi. Phase shifts corresponding to RGM calculations at laboratory energies 30, 41, 49, 59, 150, 350 and 500 MeV were inverted and the resulting local potentials compared with the local (but l-dependent) potentials obtained previously in the WKB-RGM scheme. The present l-independent potentials exhibit a smooth radial variation and show marked differences from previous results. The energy dependence arises from that of the exchange term and from the conversion of the l-dependence into an additional energy dependence. In particular, we show that the energy dependence of the volume integrals in this energy region is different from earlier WKB-RGM predictions. (orig.)

  20. Input-dependent frequency modulation of cortical gamma oscillations shapes spatial synchronization and enables phase coding.

    Lowet, Eric; Roberts, Mark; Hadjipapas, Avgis; Peter, Alina; van der Eerden, Jan; De Weerd, Peter

    2015-02-01

    Fine-scale temporal organization of cortical activity in the gamma range (∼25-80Hz) may play a significant role in information processing, for example by neural grouping ('binding') and phase coding. Recent experimental studies have shown that the precise frequency of gamma oscillations varies with input drive (e.g. visual contrast) and that it can differ among nearby cortical locations. This has challenged theories assuming widespread gamma synchronization at a fixed common frequency. In the present study, we investigated which principles govern gamma synchronization in the presence of input-dependent frequency modulations and whether they are detrimental for meaningful input-dependent gamma-mediated temporal organization. To this aim, we constructed a biophysically realistic excitatory-inhibitory network able to express different oscillation frequencies at nearby spatial locations. Similarly to cortical networks, the model was topographically organized with spatially local connectivity and spatially-varying input drive. We analyzed gamma synchronization with respect to phase-locking, phase-relations and frequency differences, and quantified the stimulus-related information represented by gamma phase and frequency. By stepwise simplification of our models, we found that the gamma-mediated temporal organization could be reduced to basic synchronization principles of weakly coupled oscillators, where input drive determines the intrinsic (natural) frequency of oscillators. The gamma phase-locking, the precise phase relation and the emergent (measurable) frequencies were determined by two principal factors: the detuning (intrinsic frequency difference, i.e. local input difference) and the coupling strength. In addition to frequency coding, gamma phase contained complementary stimulus information. Crucially, the phase code reflected input differences, but not the absolute input level. This property of relative input-to-phase conversion, contrasting with latency codes

  1. Temperature-dependent phase transitions in zeptoliter volumes of a complex biological membrane

    Nikiforov, Maxim P; Jesse, Stephen; Kalinin, Sergei V; Hohlbauch, Sophia; Proksch, Roger; King, William P; Voitchovsky, Kislon; Contera, Sonia Antoranz

    2011-01-01

    Phase transitions in purple membrane have been a topic of debate for the past two decades. In this work we present studies of a reversible transition of purple membrane in the 50-60 deg. C range in zeptoliter volumes under different heating regimes (global heating and local heating). The temperature of the reversible phase transition is 52 ± 5 deg. C for both local and global heating, supporting the hypothesis that this transition is mainly due to a structural rearrangement of bR molecules and trimers. To achieve high resolution measurements of temperature-dependent phase transitions, a new scanning probe microscopy-based method was developed. We believe that our new technique can be extended to other biological systems and can contribute to the understanding of inhomogeneous phase transitions in complex systems.

  2. Temperature and baryon-chemical-potential-dependent bag pressure for a deconfining phase transition

    Patra, B.K.; Singh, C.P.

    1996-01-01

    We explore the consequences of a bag model developed by Leonidov et al. for the deconfining phase transition in which the bag pressure is made to depend on the temperature and baryon chemical potential in order to ensure the entropy and baryon number conservation at the phase boundary together with the Gibbs construction for an equilibrium phase transition. We show that the bag pressure thus obtained yields an anomalous increasing behavior with the increasing baryon chemical potential at a fixed temperature which defies a physical interpretation. We demonstrate that the inclusion of the perturbative interactions in the QGP phase removes this difficulty. Further consequences of the modified bag pressure are discussed. copyright 1996 The American Physical Society

  3. Gait, mobility, and falls in older people

    Gschwind, Yves Josef

    2012-01-01

    My doctoral thesis contributes to the understanding of gait, mobility, and falls in older people. All presented projects investigated the most prominent and sensitive markers for fall-related gait changes, that is gait velocity and gait variability. Based on the measurement of these spatio-temporal gait parameters, particularly when using a change-sensitive dual task paradigm, it is possible to make conclusions regarding walking, balance, activities of daily living, and falls in o...

  4. Capability of 2 gait measures for detecting response to gait training in stroke survivors: Gait Assessment and Intervention Tool and the Tinetti Gait Scale.

    Zimbelman, Janice; Daly, Janis J; Roenigk, Kristen L; Butler, Kristi; Burdsall, Richard; Holcomb, John P

    2012-01-01

    To characterize the performance of 2 observational gait measures, the Tinetti Gait Scale (TGS) and the Gait Assessment and Intervention Tool (G.A.I.T.), in identifying improvement in gait in response to gait training. In secondary analysis from a larger study of multimodal gait training for stroke survivors, we measured gait at pre-, mid-, and posttreatment according to G.A.I.T. and TGS, assessing their capability to capture recovery of coordinated gait components. Large medical center. Cohort of stroke survivors (N=44) greater than 6 months after stroke. All subjects received 48 sessions of a multimodal gait-training protocol. Treatment consisted of 1.5 hours per session, 4 sessions per week for 12 weeks, receiving these 3 treatment aspects: (1) coordination exercise, (2) body weight-supported treadmill training, and (3) overground gait training, with 46% of subjects receiving functional electrical stimulation. All subjects were evaluated with the G.A.I.T. and TGS before and after completing the 48-session intervention. An additional evaluation was performed at midtreatment (after session 24). For the total subject sample, there were significant pre-/post-, pre-/mid-, and mid-/posttreatment gains for both the G.A.I.T. and the TGS. According to the G.A.I.T., 40 subjects (91%) showed improved scores, 2 (4%) no change, and 2 (4%) a worsening score. According to the TGS, only 26 subjects (59%) showed improved scores, 16 (36%) no change, and 1 (2%) a worsening score. For 1 treatment group of chronic stroke survivors, the TGS failed to identify a significant treatment response to gait training, whereas the G.A.I.T. measure was successful. The G.A.I.T. is more sensitive than the TGS for individual patients and group treatment response in identifying recovery of volitional control of gait components in response to gait training. Copyright © 2012 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  5. Simple analytical model reveals the functional role of embodied sensorimotor interaction in hexapod gaits

    Aoi, Shinya; Nachstedt, Timo; Manoonpong, Poramate; Wörgötter, Florentin; Matsuno, Fumitoshi

    2018-01-01

    Insects have various gaits with specific characteristics and can change their gaits smoothly in accordance with their speed. These gaits emerge from the embodied sensorimotor interactions that occur between the insect’s neural control and body dynamic systems through sensory feedback. Sensory feedback plays a critical role in coordinated movements such as locomotion, particularly in stick insects. While many previously developed insect models can generate different insect gaits, the functional role of embodied sensorimotor interactions in the interlimb coordination of insects remains unclear because of their complexity. In this study, we propose a simple physical model that is amenable to mathematical analysis to explain the functional role of these interactions clearly. We focus on a foot contact sensory feedback called phase resetting, which regulates leg retraction timing based on touchdown information. First, we used a hexapod robot to determine whether the distributed decoupled oscillators used for legs with the sensory feedback generate insect-like gaits through embodied sensorimotor interactions. The robot generated two different gaits and one had similar characteristics to insect gaits. Next, we proposed the simple model as a minimal model that allowed us to analyze and explain the gait mechanism through the embodied sensorimotor interactions. The simple model consists of a rigid body with massless springs acting as legs, where the legs are controlled using oscillator phases with phase resetting, and the governed equations are reduced such that they can be explained using only the oscillator phases with some approximations. This simplicity leads to analytical solutions for the hexapod gaits via perturbation analysis, despite the complexity of the embodied sensorimotor interactions. This is the first study to provide an analytical model for insect gaits under these interaction conditions. Our results clarified how this specific foot contact sensory

  6. Crystalline phase-dependent eco-toxicity of titania nanoparticles to freshwater biofilms

    Li, Kun; Qian, Jin; Wang, Peifang; Wang, Chao; Liu, Jingjing; Tian, Xin; Lu, Bianhe; Shen, Mengmeng

    2017-01-01

    The potential toxic impacts of different crystal phases of titania nanoparticles (TNPs) on freshwater biofilms, especially under ultraviolet C irradiation (UVC), are unknown. Here, adverse impacts of three phases (anatase, rutile, and P25, 50 mg L −1 respectively) with UVC irradiation (An-UV, Ru-UV, and P25-UV) on freshwater biofilms were conducted. Characterization experiments revealed that rutile TNPs had a higher water environment stability than anatase and P25 TNPs, possessing a stronger photocatalytic activity under UVC irradiation. Phase-dependent inhibition of cell viability and significant decreases of four- and five-fold in algal biomass at 12 h of exposure were observed compared with unexposed biofilms. Moreover, phase-dependent oxidative stress resulted in remarkably significant reductions (P < 0.01) of the photosynthetic yields of the biofilms, to 40.32% (P25-UV), 48.39% (An-UV), and 46.77% (Ru-UV) of the plateau value obtained in the unexposed biofilms. A shift in community composition that manifested as a strong reduction in diatoms, indicating cyanobacteria and green algae were more tolerant than diatoms when exposed to TNPs. In terms of the toxic mechanisms, rutile TNPs resulted in apoptosis by inducing excessive intracellular reactive oxygen species (ROS) production, whereas P25 and anatase TNPs tended to catalyze enormous acellular ROS lead to cell necrosis under UVC irradiation. - Highlights: • Phase-dependent response of freshwater biofilms to three TNPs was studied with UVC. • Rutile is more stable yet P25 and anatase own better photooxidation level in water. • Decrease in Chl-a and φM and a shift in algae bio-cenosis were phase-dependent. • Phase-dependent stress induced cellular or acellular ROS to reduce cells viability. • Rutile tend to induced apoptosis yet P25 and anatase prefer to cause cell necrosis. - Crystalline-dependent eco-toxicity of TNPs to freshwater biofilms show allotrope of nanoparticles must be considered

  7. Non-MTC gait cycles: An adaptive toe trajectory control strategy in older adults.

    Santhiranayagam, Braveena K; Sparrow, W A; Lai, Daniel T H; Begg, Rezaul K

    2017-03-01

    Minimum-toe-clearance (MTC) above the walking surface is a critical representation of toe-trajectory control due to its association with tripping risk. Not all gait cycles exhibit a clearly defined MTC within the swing phase but there have been few previous accounts of the biomechanical characteristics of non-MTC gait cycles. The present report investigated the within-subject non-MTC gait cycle characteristics of 15 older adults (mean 73.1 years) and 15 young controls (mean 26.1 years). Participants performed the following tasks on a motorized treadmill: preferred speed walking, dual task walking (carrying a glass of water) and a dual-task speed-matched control. Toe position-time coordinates were acquired using a 3 dimensional motion capture system. When MTC was present, toe height at MTC (MTC height ) was extracted. The proportion of non-MTC gait cycles was computed for the age groups and individuals. For non-MTC gait cycles an 'indicative' toe height at the individual's average swing phase time (MTC time ) for observed MTC cycles was averaged across multiple non-MTC gait cycles. In preferred-speed walking Young demonstrated 2.9% non-MTC gait cycles and Older 18.7%. In constrained walking conditions both groups increased non-MTC gait cycles and some older adults revealed over 90%, confirming non-MTC gait cycles as an ageing-related phenomenon in lower limb trajectory control. For all participants median indicative toe-height on non-MTC gait cycles was greater than median MTC height . This result suggests that eliminating the biomechanically hazardous MTC event by adopting more of the higher-clearance non-MTC gait cycles, is adaptive in reducing the likelihood of toe-ground contact. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Uncovering the intrinsic size dependence of hydriding phase transformations in nanocrystals.

    Bardhan, Rizia; Hedges, Lester O; Pint, Cary L; Javey, Ali; Whitelam, Stephen; Urban, Jeffrey J

    2013-10-01

    A quantitative understanding of nanocrystal phase transformations would enable more efficient energy conversion and catalysis, but has been hindered by difficulties in directly monitoring well-characterized nanoscale systems in reactive environments. We present a new in situ luminescence-based probe enabling direct quantification of nanocrystal phase transformations, applied here to the hydriding transformation of palladium nanocrystals. Our approach reveals the intrinsic kinetics and thermodynamics of nanocrystal phase transformations, eliminating complications of substrate strain, ligand effects and external signal transducers. Clear size-dependent trends emerge in nanocrystals long accepted to be bulk-like in behaviour. Statistical mechanical simulations show these trends to be a consequence of nanoconfinement of a thermally driven, first-order phase transition: near the phase boundary, critical nuclei of the new phase are comparable in size to the nanocrystal itself. Transformation rates are then unavoidably governed by nanocrystal dimensions. Our results provide a general framework for understanding how nanoconfinement fundamentally impacts broad classes of thermally driven solid-state phase transformations relevant to hydrogen storage, catalysis, batteries and fuel cells.

  9. Size-dependent and tunable crystallization of GeSbTe phase-change nanoparticles

    Chen, Bin; Ten Brink, Gert H.; Palasantzas, George; Kooi, Bart J.

    2016-12-01

    Chalcogenide-based nanostructured phase-change materials (PCMs) are considered promising building blocks for non-volatile memory due to their high write and read speeds, high data-storage density, and low power consumption. Top-down fabrication of PCM nanoparticles (NPs), however, often results in damage and deterioration of their useful properties. Gas-phase condensation based on magnetron sputtering offers an attractive and straightforward solution to continuously down-scale the PCMs into sub-lithographic sizes. Here we unprecedentedly present the size dependence of crystallization for Ge2Sb2Te5 (GST) NPs, whose production is currently highly challenging for chemical synthesis or top-down fabrication. Both amorphous and crystalline NPs have been produced with excellent size and composition control with average diameters varying between 8 and 17 nm. The size-dependent crystallization of these NPs was carefully analyzed through in-situ heating in a transmission electron microscope, where the crystallization temperatures (Tc) decrease when the NPs become smaller. Moreover, methane incorporation has been observed as an effective method to enhance the amorphous phase stability of the NPs. This work therefore elucidates that GST NPs synthesized by gas-phase condensation with tailored properties are promising alternatives in designing phase-change memories constrained by optical lithography limitations.

  10. Trunk lean gait decreases multi-segmental coordination in the vertical direction.

    Tokuda, Kazuki; Anan, Masaya; Sawada, Tomonori; Tanimoto, Kenji; Takeda, Takuya; Ogata, Yuta; Takahashi, Makoto; Kito, Nobuhiro; Shinkoda, Koichi

    2017-11-01

    [Purpose] The strategy of trunk lean gait to reduce external knee adduction moment (KAM) may affect multi-segmental synergy control of center of mass (COM) displacement. Uncontrolled manifold (UCM) analysis is an evaluation index to understand motor variability. The purpose of this study was to investigate how motor variability is affected by using UCM analysis on adjustment of the trunk lean angle. [Subjects and Methods] Fifteen healthy young adults walked at their preferred speed under two conditions: normal and trunk lean gait. UCM analysis was performed with respect to the COM displacement during the stance phase. The KAM data were analyzed at the points of the first KAM peak during the stance phase. [Results] The KAM during trunk lean gait was smaller than during normal gait. Despite a greater segmental configuration variance with respect to mediolateral COM displacement during trunk lean gait, the synergy index was not significantly different between the two conditions. The synergy index with respect to vertical COM displacement during trunk lean gait was smaller than that during normal gait. [Conclusion] These results suggest that trunk lean gait is effective in reducing KAM; however, it may decrease multi-segmental movement coordination of COM control in the vertical direction.

  11. Effect of Rhythmic Auditory Stimulation on Hemiplegic Gait Patterns.

    Shin, Yoon-Kyum; Chong, Hyun Ju; Kim, Soo Ji; Cho, Sung-Rae

    2015-11-01

    The purpose of our study was to investigate the effect of gait training with rhythmic auditory stimulation (RAS) on both kinematic and temporospatial gait patterns in patients with hemiplegia. Eighteen hemiplegic patients diagnosed with either cerebral palsy or stroke participated in this study. All participants underwent the 4-week gait training with RAS. The treatment was performed for 30 minutes per each session, three sessions per week. RAS was provided with rhythmic beats using a chord progression on a keyboard. Kinematic and temporospatial data were collected and analyzed using a three-dimensional motion analysis system. Gait training with RAS significantly improved both proximal and distal joint kinematic patterns in hip adduction, knee flexion, and ankle plantar flexion, enhancing the gait deviation index (GDI) as well as ameliorating temporal asymmetry of the stance and swing phases in patients with hemiplegia. Stroke patients with previous walking experience demonstrated significant kinematic improvement in knee flexion in mid-swing and ankle dorsiflexion in terminal stance. Among stroke patients, subacute patients showed a significantly increased GDI score compared with chronic patients. In addition, household ambulators showed a significant effect on reducing anterior tilt of the pelvis with an enhanced GDI score, while community ambulators significantly increased knee flexion in mid-swing phase and ankle dorsiflexion in terminal stance phase. Gait training with RAS has beneficial effects on both kinematic and temporospatial patterns in patients with hemiplegia, providing not only clinical implications of locomotor rehabilitation with goal-oriented external feedback using RAS but also differential effects according to ambulatory function.

  12. Late Protein Synthesis-Dependent Phases in CTA Long-Term Memory: BDNF Requirement

    Martínez-Moreno, Araceli; Rodríguez-Durán, Luis F.; Escobar, Martha L.

    2011-01-01

    It has been proposed that long-term memory persistence requires a late protein synthesis-dependent phase, even many hours after memory acquisition. Brain-derived neurotrophic factor (BDNF) is an essential protein synthesis product that has emerged as one of the most potent molecular mediators for long-term synaptic plasticity. Studies in the rat hippocampus have been shown that BDNF is capable to rescue the late-phase of long-term potentiation as well as the hippocampus-related long-term memo...

  13. Robotic gait trainer in water: development of an underwater gait-training orthosis.

    Miyoshi, Tasuku; Hiramatsu, Kazuaki; Yamamoto, Shin-Ichiro; Nakazawa, Kimitaka; Akai, Masami

    2008-01-01

    To develop a robotic gait trainer that can be used in water (RGTW) and achieve repetitive physiological gait patterns to improve the movement dysfunctions. The RGTW is a hip-knee-ankle-foot orthosis with pneumatic actuators; the control software was developed on the basis of the angular motions of the hip and knee joint of a healthy subject as he walked in water. Three-dimensional motions and electromyographic (EMG) activities were recorded in nine healthy subjects to evaluate the efficacy of using the RGTW while walking on a treadmill in water. The device could preserve the angular displacement patterns of the hip and knee and foot trajectories under all experimental conditions. The tibialis anterior EMG activities in the late swing phase and the biceps femoris throughout the stance phase were reduced whose joint torques were assisted by the RGTW while walking on a treadmill in water. Using the RGTW could expect not only the effect of the hydrotherapy but also the standard treadmill gait training, in particular, and may be particularly effective for treating individuals with hip joint movement dysfunction.

  14. Effects of obesity and chronic low back pain on gait

    Galli Manuela

    2011-09-01

    Full Text Available Abstract Background Obesity is often associated with low back pain (LBP. Despite empirical evidence that LBP induces gait abnormalities, there is a lack of quantitative analysis of the combined effect of obesity and LBP on gait. The aim of our study was to quantify the gait pattern of obese subjects with and without LBP and normal-mass controls by using Gait Analysis (GA, in order to investigate the cumulative effects of obesity and LBP on gait. Methods Eight obese females with chronic LBP (OLG; age: 40.5 ± 10.1 years; BMI: 42.39 ± 5.47 Kg/m2, 10 obese females (OG; age: 33.6 ± 5.2 years; BMI: 39.26 ± 2.39 Kg/m2 and 10 healthy female subjects (CG; age: 33.4 ± 9.6 years; BMI: 22.8 ± 3.2 Kg/m2, were enrolled in this study and assessed with video recording and GA. Results and Discussion OLG showed longer stance duration and shorter step length when compared to OG and CG. They also had a low pelvis and hip ROM on the frontal plane, a low knee flexion in the swing phase and knee range of motion, a low dorsiflexion in stance and swing as compared to OG. No statistically significant differences were found in ankle power generation at push-off between OLG and OG, which appeared lower if compared to CG. At hip level, both OLG and OG exhibited high power generation levels during stance, with OLG showing the highest values. Conclusions Our results demonstrated that the association of obesity and LBP affects more the gait pattern than obesity alone. OLG were in fact characterised by an altered knee and ankle strategy during gait as compared to OG and CG. These elements may help optimizing rehabilitation planning and treatment in these patients.

  15. Gait Deviation Index, Gait Profile Score and Gait Variable Score in children with spastic cerebral palsy

    Rasmussen, Helle Mätzke; Nielsen, Dennis Brandborg; Pedersen, Niels Wisbech

    2015-01-01

    Abstract The Gait Deviation Index (GDI) and Gait Profile Score (GPS) are the most used summary measures of gait in children with cerebral palsy (CP). However, the reliability and agreement of these indices have not been investigated, limiting their clinimetric quality for research and clinical...... to good reliability with ICCs of 0.4–0.7. The agreement for the GDI and the logarithmically transformed GPS, in terms of the standard error of measurement as a percentage of the grand mean (SEM%) varied from 4.1 to 6.7%, whilst the smallest detectable change in percent (SDC%) ranged from 11.3 to 18...

  16. Relativistic Random-Phase Approximation with Density-dependent Meson-nucleon Couplings at Finite Temperature

    Niu, Y.; Paar, N.; Vretenar, D.; Meng, J.

    2009-01-01

    The fully self-consistent relativistic random-phase approximation (RRPA) framework based on effective interactions with a phenomenological density dependence is extended to finite temperatures. The RRPA configuration space is built from the spectrum of single-nucleon states at finite temperature obtained by the temperature dependent relativistic mean field (RMF-T) theory based on effective Lagrangian with density dependent meson-nucleon vertex functions. As an illustration, the dependence of binding energy, radius, entropy and single particle levels on temperature for spherical nucleus 2 08P b is investigated in RMF-T theory. The finite temperature RRPA has been employed in studies of giant monopole and dipole resonances, and the evolution of resonance properties has been studied as a function of temperature. In addition, exotic modes of excitation have been systematically explored at finite temperatures, with an emphasis on the case of pygmy dipole resonances.(author)

  17. Pathways linking regional hyperintensities in the brain and slower gait.

    Bolandzadeh, Niousha; Liu-Ambrose, Teresa; Aizenstein, Howard; Harris, Tamara; Launer, Lenore; Yaffe, Kristine; Kritchevsky, Stephen B; Newman, Anne; Rosano, Caterina

    2014-10-01

    associations. The mediation analyses also found that DSST significantly mediated the associations between WMHs and gait speed. Our models were adjusted for age, sex, BMI, quadriceps strength, years of education, standing height, and prevalent hypertension. The impact, direct or indirect, of WMHs on gait speed depended on their location and was mediated by executive function. Thus, multi-faceted interventions targeting executive control functions as well as motor functions, such as balance and strength training, are candidates to the maintenance of mobility across the lifespan. Copyright © 2014 Elsevier Inc. All rights reserved.

  18. Gait performance is not influenced by working memory when walking at a self-selected pace.

    Grubaugh, Jordan; Rhea, Christopher K

    2014-02-01

    Gait performance exhibits patterns within the stride-to-stride variability that can be indexed using detrended fluctuation analysis (DFA). Previous work employing DFA has shown that gait patterns can be influenced by constraints, such as natural aging or disease, and they are informative regarding a person's functional ability. Many activities of daily living require concurrent performance in the cognitive and gait domains; specifically working memory is commonly engaged while walking, which is considered dual-tasking. It is unknown if taxing working memory while walking influences gait performance as assessed by DFA. This study used a dual-tasking paradigm to determine if performance decrements are observed in gait or working memory when performed concurrently. Healthy young participants (N = 16) performed a working memory task (automated operation span task) and a gait task (walking at a self-selected speed on a treadmill) in single- and dual-task conditions. A second dual-task condition (reading while walking) was included to control for visual attention, but also introduced a task that taxed working memory over the long term. All trials involving gait lasted at least 10 min. Performance in the working memory task was indexed using five dependent variables (absolute score, partial score, speed error, accuracy error, and math error), while gait performance was indexed by quantifying the mean, standard deviation, and DFA α of the stride interval time series. Two multivariate analyses of variance (one for gait and one for working memory) were used to examine performance in the single- and dual-task conditions. No differences were observed in any of the gait or working memory dependent variables as a function of task condition. The results suggest the locomotor system is adaptive enough to complete a working memory task without compromising gait performance when walking at a self-selected pace.

  19. Extracellular matrix-dependent myosin dynamics during G1-S phase cell cycle progression in hepatocytes

    Bhadriraju, Kiran; Hansen, Linda K.

    2004-01-01

    Cell spreading and proliferation are tightly coupled in anchorage-dependent cells. While adhesion-dependent proliferation signals require an intact actin cytoskeleton, and some of these signals such as ERK activation have been characterized, the role of myosin in spreading and cell cycle progression under different extracellular matrix (ECM) conditions is not known. Studies presented here examine changes in myosin activity in freshly isolated hepatocytes under ECM conditions that promote either proliferation (high fibronectin density) or growth arrest (low fibronectin density). Three different measures were obtained and related to both spreading and cell cycle progression: myosin protein levels and association with cytoskeleton, myosin light chain phosphorylation, and its ATPase activity. During the first 48 h in culture, corresponding with transit through G1 phase, there was a six-fold increase in both myosin protein levels and myosin association with actin cytoskeleton. There was also a steady increase in myosin light chain phosphorylation and ATPase activity with spreading, which did not occur in non-spread, growth-arrested cells on low density of fibronectin. Myosin-inhibiting drugs blocked ERK activation, cyclin D1 expression, and S phase entry. Overexpression of the cell cycle protein cyclin D1 overcame both ECM-dependent and actomyosin-dependent inhibition of DNA synthesis, suggesting that cyclin D1 is a key event downstream of myosin-dependent cell cycle regulation

  20. Oxygen vacancies dependent phase transition of Y{sub 2}O{sub 3} films

    Yu, Pengfei; Zhang, Kan [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun 130012 (China); Huang, Hao [Titanium Alloys Lab. Beijing Institute of Aeronautical Materials, Beijing 81-15 100095 (China); Wen, Mao, E-mail: Wenmao225@jlu.edu.cn [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun 130012 (China); Li, Quan; Zhang, Wei; Hu, Chaoquan [Department of Materials Science, State Key Laboratory of Superhard Materials, and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun 130012 (China); Zheng, Weitao, E-mail: WTZheng@jlu.edu.cn [Department of Materials Science, State Key Laboratory of Automotive Simulation and Control and Key Laboratory of Automobile Materials, MOE, Jilin University, Changchun 130012 (China)

    2017-07-15

    Highlights: • Oxygen vacancies for Y{sub 2}O{sub 3} films increase monotonously with increasing T{sub s}. • Oxygen vacancies can promote the nucleation of monoclinic phase. • That monoclinic phase with oxygen deficiency is not thermodynamic stable at high temperature. • Phase transition from monoclinic to oxygen defective occurs at high concentrations of oxygen vacancies. • High hardness just appears in Y{sub 2}O{sub 3} films with mixed phase configurations. - Abstract: Y{sub 2}O{sub 3} films have great application potential in high-temperature metal matrix composite and nuclear engineering, used as interface diffusion and reaction barrier coating owing to their excellent thermal and chemical stability, high melting point and extremely negative Gibbs formation energy, and thus their structural and mechanical properties at elevated temperature are especially important. Oxygen vacancies exist commonly in yttrium oxide (Y{sub 2}O{sub 3}) thin films and act strongly on the phase structure and properties, but oxygen vacancies dependent phase transition at elevated temperature has not been well explored yet. Y{sub 2}O{sub 3} thin films with different oxygen vacancy concentrations have been achieved by reactive sputtering through varying substrate temperature (T{sub s}), in which oxygen vacancies increase monotonously with increasing T{sub s}. For as-deposited Y{sub 2}O{sub 3} films, oxygen vacancies present at high T{sub s} can promote the nucleation of monoclinic phase, meanwhile, high T{sub s} can induce the instability of monoclinic phase. Thus their competition results in forming mixed phases of cubic and monoclinic at high T{sub s}. During vacuum annealing at 1000 °C, a critical oxygen vacancy concentration is observed, below which phase transition from monoclinic to cubic takes place, and above which phase transfer from monoclinic to the oxygen defective phase (ICDD file no. 39-1063), accompanying by stress reversal from compressive to tensile and

  1. Secure and privacy enhanced gait authentication on smart phone.

    Hoang, Thang; Choi, Deokjai

    2014-01-01

    Smart environments established by the development of mobile technology have brought vast benefits to human being. However, authentication mechanisms on portable smart devices, particularly conventional biometric based approaches, still remain security and privacy concerns. These traditional systems are mostly based on pattern recognition and machine learning algorithms, wherein original biometric templates or extracted features are stored under unconcealed form for performing matching with a new biometric sample in the authentication phase. In this paper, we propose a novel gait based authentication using biometric cryptosystem to enhance the system security and user privacy on the smart phone. Extracted gait features are merely used to biometrically encrypt a cryptographic key which is acted as the authentication factor. Gait signals are acquired by using an inertial sensor named accelerometer in the mobile device and error correcting codes are adopted to deal with the natural variation of gait measurements. We evaluate our proposed system on a dataset consisting of gait samples of 34 volunteers. We achieved the lowest false acceptance rate (FAR) and false rejection rate (FRR) of 3.92% and 11.76%, respectively, in terms of key length of 50 bits.

  2. Secure and Privacy Enhanced Gait Authentication on Smart Phone

    Thang Hoang

    2014-01-01

    Full Text Available Smart environments established by the development of mobile technology have brought vast benefits to human being. However, authentication mechanisms on portable smart devices, particularly conventional biometric based approaches, still remain security and privacy concerns. These traditional systems are mostly based on pattern recognition and machine learning algorithms, wherein original biometric templates or extracted features are stored under unconcealed form for performing matching with a new biometric sample in the authentication phase. In this paper, we propose a novel gait based authentication using biometric cryptosystem to enhance the system security and user privacy on the smart phone. Extracted gait features are merely used to biometrically encrypt a cryptographic key which is acted as the authentication factor. Gait signals are acquired by using an inertial sensor named accelerometer in the mobile device and error correcting codes are adopted to deal with the natural variation of gait measurements. We evaluate our proposed system on a dataset consisting of gait samples of 34 volunteers. We achieved the lowest false acceptance rate (FAR and false rejection rate (FRR of 3.92% and 11.76%, respectively, in terms of key length of 50 bits.

  3. Analysis of foot load during ballet dancers' gait.

    Prochazkova, Marketa; Tepla, Lucie; Svoboda, Zdenek; Janura, Miroslav; Cieslarová, Miloslava

    2014-01-01

    Ballet is an art that puts extreme demands on the dancer's musculoskeletal system and therefore significantly affects motor behavior of the dancers. The aim of our research was to compare plantar pressure distribution during stance phase of gait between a group of professional ballet dancers and non-dancers. Thirteen professional dancers (5 men, 8 women; mean age of 24.1 ± 3.8 years) and 13 nondancers (5 men, 8 women; mean age of 26.1 ± 5.3 years) participated in this study. Foot pressure analysis during gait was collected using a 2 m pressure plate. The participants were instructed to walk across the platform at a self-selected pace barefoot. Three gait cycles were necessary for the data analysis. The results revealed higher (p < 0.05) pressure peaks in medial edge of forefoot during gait for dancers in comparison with nondancers. Furthermore, differences in total foot loading and foot loading duration of rearfoot was higher (p < 0.05) in dancers as well. We can attribute these differences to long-term and intensive dancing exercises that can change the dancer's gait stereotype.

  4. Seafloor age dependence of Rayleigh wave phase velocities in the Indian Ocean

    Godfrey, Karen E.; Dalton, Colleen A.; Ritsema, Jeroen

    2017-05-01

    Variations in the phase velocity of fundamental-mode Rayleigh waves across the Indian Ocean are determined using two inversion approaches. First, variations in phase velocity as a function of seafloor age are estimated using a pure-path age-dependent inversion method. Second, a two-dimensional parameterization is used to solve for phase velocity within 1.25° × 1.25° grid cells. Rayleigh wave travel time delays have been measured between periods of 38 and 200 s. The number of measurements in the study area ranges between 4139 paths at a period of 200 s and 22,272 paths at a period of 40 s. At periods Rodriguez Triple Junction and the Australian-Antarctic Discordance and anomalously low velocities immediately to the west of the Central Indian Ridge.

  5. Model Predictive Control-based gait pattern generation for wearable exoskeletons.

    Wang, Letian; van Asseldonk, Edwin H F; van der Kooij, Herman

    2011-01-01

    This paper introduces a new method for controlling wearable exoskeletons that do not need predefined joint trajectories. Instead, it only needs basic gait descriptors such as step length, swing duration, and walking speed. End point Model Predictive Control (MPC) is used to generate the online joint trajectories based on these gait parameters. Real-time ability and control performance of the method during the swing phase of gait cycle is studied in this paper. Experiments are performed by helping a human subject swing his leg with different patterns in the LOPES gait trainer. Results show that the method is able to assist subjects to make steps with different step length and step duration without predefined joint trajectories and is fast enough for real-time implementation. Future study of the method will focus on controlling the exoskeletons in the entire gait cycle. © 2011 IEEE

  6. On the Size Dependence of Molar and Specific Properties of Independent Nano-phases and Those in Contact with Other Phases

    Kaptay, George

    2018-05-01

    Nano-materials are materials with at least one nano-phase. A nano-phase is a phase with at least one of its dimensions below 100 nm. It is shown here that nano-phases have at least 1% of their atoms along their surface layer. The ratio of surface atoms is proportional to the specific surface area of the phase, defined as the ratio of its surface area to its volume. Each specific/molar property has its bulk value and its surface value for the given phase, being always different, as the energetic states of the atoms in the bulk and in the surface layer of a phase are different. The average specific/molar property of a nano-phase is modeled here as a linear combination of the bulk and surface values of the same property, scaled with the ratio of the surface atoms. That makes the performance of all nano-phases proportional to their specific surface area. As the characteristic size of the nano-phase is inversely proportional to its specific surface area, all specific/molar properties of nano-phases are inversely proportional to the characteristic size of the phase. This is applied to the size dependence of the molar Gibbs energy of the nano-phase, which appears to be in agreement with the thermodynamics of Gibbs. This agreement proves the general validity of the present model on the size dependence of the specific/molar properties of independent nano-phases. It is shown that the properties of nano-phases are different for independent nano-phases (surrounded only by their equilibrium vapor phase) and for nano-phases in multi-phase situations, such as a liquid nano-droplet in the sessile drop configuration.

  7. Dynamic phase transitions in a cylindrical Ising nanowire under a time-dependent oscillating magnetic field

    Deviren, Bayram; Kantar, Ersin; Keskin, Mustafa

    2012-01-01

    The dynamic phase transitions in a cylindrical Ising nanowire system under a time-dependent oscillating external magnetic field for both ferromagnetic and antiferromagnetic interactions are investigated within the effective-field theory with correlations and the Glauber-type stochastic dynamics approach. The effective-field dynamic equations for the average longitudinal magnetizations on the surface shell and core are derived by employing the Glauber transition rates. Temperature dependence of the dynamic magnetizations, the dynamic total magnetization, the hysteresis loop areas and the dynamic correlations are investigated in order to characterize the nature (first- or second-order) of the dynamic transitions as well as the dynamic phase transition temperatures and the compensation behaviors. The system strongly affected by the surface situations. Some characteristic phenomena are found depending on the ratio of the physical parameters in the surface shell and the core. According to the values of Hamiltonian parameters, five different types of compensation behaviors in the Néel classification nomenclature exist in the system. The system also exhibits a reentrant behavior. - Highlights: ► The dynamic aspects of a cylindrical Ising nanowire are investigated in detail. ► The dynamic magnetizations, hysteresis loop areas and correlations are calculated. ► We studied both the FM and AFM interactions within the EFT with correlations. ► Some characteristic phenomena are found depending on the interaction parameters. ► We obtained five different types of compensation behaviors and reentrant behavior.

  8. Dynamic phase transitions in a cylindrical Ising nanowire under a time-dependent oscillating magnetic field

    Deviren, Bayram [Department of Physics, Nevsehir University, 50300 Nevsehir (Turkey); Kantar, Ersin [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Keskin, Mustafa, E-mail: keskin@erciyes.edu.tr [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)

    2012-07-15

    The dynamic phase transitions in a cylindrical Ising nanowire system under a time-dependent oscillating external magnetic field for both ferromagnetic and antiferromagnetic interactions are investigated within the effective-field theory with correlations and the Glauber-type stochastic dynamics approach. The effective-field dynamic equations for the average longitudinal magnetizations on the surface shell and core are derived by employing the Glauber transition rates. Temperature dependence of the dynamic magnetizations, the dynamic total magnetization, the hysteresis loop areas and the dynamic correlations are investigated in order to characterize the nature (first- or second-order) of the dynamic transitions as well as the dynamic phase transition temperatures and the compensation behaviors. The system strongly affected by the surface situations. Some characteristic phenomena are found depending on the ratio of the physical parameters in the surface shell and the core. According to the values of Hamiltonian parameters, five different types of compensation behaviors in the Neel classification nomenclature exist in the system. The system also exhibits a reentrant behavior. - Highlights: Black-Right-Pointing-Pointer The dynamic aspects of a cylindrical Ising nanowire are investigated in detail. Black-Right-Pointing-Pointer The dynamic magnetizations, hysteresis loop areas and correlations are calculated. Black-Right-Pointing-Pointer We studied both the FM and AFM interactions within the EFT with correlations. Black-Right-Pointing-Pointer Some characteristic phenomena are found depending on the interaction parameters. Black-Right-Pointing-Pointer We obtained five different types of compensation behaviors and reentrant behavior.

  9. 0 - π Quantum transition in a carbon nanotube Josephson junction: Universal phase dependence and orbital degeneracy

    Delagrange, R.; Weil, R.; Kasumov, A.; Ferrier, M.; Bouchiat, H.; Deblock, R.

    2018-05-01

    In a quantum dot hybrid superconducting junction, the behavior of the supercurrent is dominated by Coulomb blockade physics, which determines the magnetic state of the dot. In particular, in a single level quantum dot singly occupied, the sign of the supercurrent can be reversed, giving rise to a π-junction. This 0 - π transition, corresponding to a singlet-doublet transition, is then driven by the gate voltage or by the superconducting phase in the case of strong competition between the superconducting proximity effect and Kondo correlations. In a two-level quantum dot, such as a clean carbon nanotube, 0- π transitions exist as well but, because more cotunneling processes are allowed, are not necessarily associated to a magnetic state transition of the dot. In this proceeding, after a review of 0- π transitions in Josephson junctions, we present measurements of current-phase relation in a clean carbon nanotube quantum dot, in the single and two-level regimes. In the single level regime, close to orbital degeneracy and in a regime of strong competition between local electronic correlations and superconducting proximity effect, we find that the phase diagram of the phase-dependent transition is a universal characteristic of a discontinuous level-crossing quantum transition at zero temperature. In the case where the two levels are involved, the nanotube Josephson current exhibits a continuous 0 - π transition, independent of the superconducting phase, revealing a different physical mechanism of the transition.

  10. Effects of Menstrual Phase-Dependent Resistance Training Frequency on Muscular Hypertrophy and Strength.

    Sakamaki-Sunaga, Mikako; Min, Seokki; Kamemoto, Kayoko; Okamoto, Takanobu

    2016-06-01

    The present study investigated how different training frequencies during menstrual phases affect muscle hypertrophy and strength. Fourteen eumenorrheic women performed 3 sets of arm curls (8-15 repetitions) until failure for 12 weeks. Depending on the menstrual cycle phase, each subject trained each arm separately after either a 3- or a 1-d·wk training protocol during the follicular phase (FP-T) and a 3- or 1-d·wk training protocol during the luteal phase (LP-T). Cross-sectional area (CSA), 1 repetition maximum, and maximum voluntary contraction significantly increased 6.2 ± 4.4, 36.4 ± 11.9, and 16.7 ± 5.6%, respectively (p ≤ 0.05 vs. before training), in the FP-T group and 7.8 ± 4.2, 31.8 ± 14.1, and 14.9 ± 12.7%, respectively (p ≤ 0.05 vs. before training), in the LP-T group. Changes in CSA between the FP-T and the LP-T groups significantly and positively correlated (r = 0.54, p ≤ 0.05). There were no major differences among the different training protocols with regard to muscle hypertrophy and strength. Therefore, we suggest that variations in female hormones induced by the menstrual cycle phases do not significantly contribute to muscle hypertrophy and strength gains during 12 weeks of resistance training.

  11. Phase-dependent dynamic potential of magnetically coupled two-degree-of-freedom bistable energy harvester.

    Kim, Pilkee; Nguyen, Minh Sang; Kwon, Ojin; Kim, Young-Jin; Yoon, Yong-Jin

    2016-09-28

    A system of magnetically coupled oscillators has been recently considered as a promising compact structure to integrate multiple bistable energy harvesters (BEHs), but its design is not straightforward owing to its varying potential energy pattern, which has not been understood completely yet. This study introduces the concept of phase-dependent dynamic potential in a magnetically coupled BEH system with two degrees of freedom (DOFs) to explain the underlying principle of the complicated dynamics of the system. Through theoretical simulations and analyses, two distinct dynamic regimes, called the out-of-phase and in-phase mode regimes in this report, are found to exist in the frequency regions of the 1 st and 2 nd primary intrawell resonances. For the out-of-phase mode regime, the frequency displacement (and output power) responses of the 2-DOF BEH system exhibit typical double-well dynamics, whereas for the in-phase mode regime, only single-well dynamics is observed though the system is statically bistable. These dynamic regimes are also revealed to be caused by the difference in the dynamic potential energy trajectories propagating on a high-dimensional potential energy surface. The present approach to the dynamics of the 2-DOF BEH system can be extended and applied to higher-DOF systems, which sheds light on compact and efficient designs of magnetically coupled BEH chain structures.

  12. Angular-dependent light scattering from cancer cells in different phases of the cell cycle.

    Lin, Xiaogang; Wan, Nan; Weng, Lingdong; Zhou, Yong

    2017-10-10

    Cancer cells in different phases of the cell cycle result in significant differences in light scattering properties. In order to harvest cancer cells in particular phases of the cell cycle, we cultured cancer cells through the process of synchronization. Flow cytometric analysis was applied to check the results of cell synchronization and prepare for light scattering measurements. Angular-dependent light scattering measurements of cancer cells arrested in the G1, S, and G2 phases have been performed. Based on integral calculations for scattering intensities from 5° to 10° and from 110° to 150°, conclusions have been reached. Clearly, the sizes of the cancer cells in different phases of the cell cycle dominated the forward scatter. Accompanying the increase of cell size with the progression of the cell cycle, the forward scattering intensity also increased. Meanwhile, the DNA content of cancer cells in every phase of the cell cycle is responsible for light scattering at large scatter angles. The higher the DNA content of cancer cells was, the greater the positive effect on the high-scattering intensity. As expected, understanding the relationships between the light scattering from cancer cells and cell cycles will aid in the development of cancer diagnoses. Also, it may assist in the guidance of antineoplastic drugs clinically.

  13. Cell cycle phase dependent emergence of thymidylate synthase studied by monoclonal antibody (M-TS-4).

    Shibui, S; Hoshino, T; Iwasaki, K; Nomura, K; Jastreboff, M M

    1989-05-01

    A method of identifying thymidylate synthase (TS) at the cellular level was developed using anti-TS monoclonal antibody (M-TS-4), a monoclonal antibody created against purified TS from a HeLa cell line. In HeLa cells and four human glioma cell lines (U-251, U-87, 343-MGA, and SF-188), TS was identified primarily in the cytoplasm. Autoradiographic and flow cytometric studies showed that TS appeared mainly in the G1 phase and subsided early in the S phase; thus, the G1 phase can be divided into TS-positive and -negative fractions. Nuclear TS was not demonstrated unequivocally with M-TS-4, and the relationship between nuclear TS and DNA synthesis could not be determined. Although the percentage of TS-positive cells was larger than the S-phase fraction measured by autoradiography after a pulse of tritiated thymidine or by the immunoperoxidase method using BUdR, the ratios were within a similar range (1.2-1.4) in all cell lines studied. Therefore, the S-phase fraction can be estimated indirectly from the percentage of TS-positive cells measured by M-TS-4. Because the emergence of TS detected by our method is cell cycle dependent, M-TS-4 may be useful for biochemical studies of TS and for cytokinetic analysis.

  14. Three-Dimensional Trunk and Lower Limbs Characteristics during Gait in Patients with Huntington's Disease

    Elzbieta Mirek

    2017-10-01

    Full Text Available Objective: A number of studies on gait disturbances have been conducted, however, no clear pattern of gait disorders was described. The aim of the study was to characterize the gait pattern in HD patients by conducting analysis of mean angular movement changes the lower limb joints and trunk (kinematics parameters.Methods: The study group consisted of 30 patients with HD (17 women and 13 men. The reference data include the results of 30 healthy subjects (17 women and 13 men. Registration of gait with the Vicon 250 system was performed using passive markers attached to specific anthropometric points directly on the skin, based on the Golem biomechanical model (Oxford Metrics Ltd.. The research group and the control group were tested once.Results: Statistically significant (p < 0.05 angular changes in gait cycle for HD patients were observed in: insufficient plantar flexion during Loading Response and Pre-swing phases; insufficient flexion of the knee joint during Initial Swing and Mid Swing phases; excessive flexion of the hip in Terminal Stance and Pre-swing phases and over-normative forward inclination of the trunk in all gait phases. It should be noted that the group of patients with HD obtained, for all the mean angular movement changes higher standard deviation.Conclusion: A characteristic gait disorder common to all patients with HD occurring throughout the whole duration of the gait cycle is a pathological anterior tilt of the trunk. The results will significantly contribute to programming physiotherapy for people with HD, aimed at stabilizing the trunk in a position of extension during gait.

  15. Gait strategy changes with acceleration to accommodate the biomechanical constraint on push-off propulsion.

    Oh, Keonyoung; Baek, Juhyun; Park, Sukyung

    2012-11-15

    To maintain steady and level walking, push-off propulsion during the double support phase compensates for the energy loss through heel strike collisions in an energetically optimal manner. However, a large portion of daily gait activities also contains transient gait responses, such as acceleration or deceleration, during which the observed dominance of the push-off work or the energy optimality may not hold. In this study, we examined whether the push-off propulsion during the double support phase served as a major energy source for gait acceleration, and we also studied the energetic optimality of accelerated gait using a simple bipedal walking model. Seven healthy young subjects participated in the over-ground walking experiments. The subjects walked at four different constant gait speeds ranging from a self-selected speed to a maximum gait speed, and then they accelerated their gait from zero to the maximum gait speed using a self-selected acceleration ratio. We measured the ground reaction force (GRF) of three consecutive steps and the corresponding leg configuration using force platforms and an optical marker system, respectively, and we compared the mechanical work performed by the GRF during each single and double support phase. In contrast to the model prediction of an increase in the push-off propulsion that is proportional to the acceleration and minimizes the mechanical energy cost, the push-off propulsion was slightly increased, and a significant increase in the mechanical work during the single support phase was observed. The results suggest that gait acceleration occurs while accommodating a feasible push-off propulsion constraint. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Late protein synthesis-dependent phases in CTA long-term memory: BDNF requirement

    Araceli eMartínez-Moreno

    2011-09-01

    Full Text Available It has been proposed that long-term memory persistence requires a late protein synthesis-dependent phase, even many hours after memory acquisition. Brain-derived neurotrophic factor (BDNF is an essential protein synthesis product that has emerged as one of the most potent molecular mediators for long-term synaptic plasticity. Studies in the rat hippocampus have been shown that BDNF is capable to rescue the late-phase of long-term potentiation as well as the hippocampus-related long-term memory when protein synthesis was inhibited. Our previous studies on the insular cortex (IC, a region of the temporal cortex implicated in the acquisition and storage of conditioned taste aversion (CTA, have demonstrated that intracortical delivery of BDNF reverses the deficit in CTA memory caused by the inhibition of IC protein synthesis due to anisomycin administration during early acquisition. In this work, we first analyze whether CTA memory storage is protein synthesis dependent in different time-windows. We observed that CTA memory become sensible to protein synthesis inhibition 5 and 7 hours after acquisition. Then, we explore the effect of BDNF delivery (2 μg/2 μl per side in the IC during those late protein synthesis-dependent phases. Our results show that BDNF reverses the CTA memory deficit produced by protein synthesis inhibition in both phases. These findings support the notion that recurrent rounds of consolidation-like events take place in the neocortex for maintenance of CTA memory trace and that BDNF is an essential component of these processes.

  17. Late Protein Synthesis-Dependent Phases in CTA Long-Term Memory: BDNF Requirement.

    Martínez-Moreno, Araceli; Rodríguez-Durán, Luis F; Escobar, Martha L

    2011-01-01

    It has been proposed that long-term memory (LTM) persistence requires a late protein synthesis-dependent phase, even many hours after memory acquisition. Brain-derived neurotrophic factor (BDNF) is an essential protein synthesis product that has emerged as one of the most potent molecular mediators for long-term synaptic plasticity. Studies in the rat hippocampus have been shown that BDNF is capable to rescue the late-phase of long-term potentiation as well as the hippocampus-related LTM when protein synthesis was inhibited. Our previous studies on the insular cortex (IC), a region of the temporal cortex implicated in the acquisition and storage of conditioned taste aversion (CTA), have demonstrated that intracortical delivery of BDNF reverses the deficit in CTA memory caused by the inhibition of IC protein synthesis due to anisomycin administration during early acquisition. In this work, we first analyze whether CTA memory storage is protein synthesis-dependent in different time windows. We observed that CTA memory become sensible to protein synthesis inhibition 5 and 7 h after acquisition. Then, we explore the effect of BDNF delivery (2 μg/2 μl per side) in the IC during those late protein synthesis-dependent phases. Our results show that BDNF reverses the CTA memory deficit produced by protein synthesis inhibition in both phases. These findings support the notion that recurrent rounds of consolidation-like events take place in the neocortex for maintenance of CTA memory trace and that BDNF is an essential component of these processes.

  18. Late Protein Synthesis-Dependent Phases in CTA Long-Term Memory: BDNF Requirement

    Martínez-Moreno, Araceli; Rodríguez-Durán, Luis F.; Escobar, Martha L.

    2011-01-01

    It has been proposed that long-term memory (LTM) persistence requires a late protein synthesis-dependent phase, even many hours after memory acquisition. Brain-derived neurotrophic factor (BDNF) is an essential protein synthesis product that has emerged as one of the most potent molecular mediators for long-term synaptic plasticity. Studies in the rat hippocampus have been shown that BDNF is capable to rescue the late-phase of long-term potentiation as well as the hippocampus-related LTM when protein synthesis was inhibited. Our previous studies on the insular cortex (IC), a region of the temporal cortex implicated in the acquisition and storage of conditioned taste aversion (CTA), have demonstrated that intracortical delivery of BDNF reverses the deficit in CTA memory caused by the inhibition of IC protein synthesis due to anisomycin administration during early acquisition. In this work, we first analyze whether CTA memory storage is protein synthesis-dependent in different time windows. We observed that CTA memory become sensible to protein synthesis inhibition 5 and 7 h after acquisition. Then, we explore the effect of BDNF delivery (2 μg/2 μl per side) in the IC during those late protein synthesis-dependent phases. Our results show that BDNF reverses the CTA memory deficit produced by protein synthesis inhibition in both phases. These findings support the notion that recurrent rounds of consolidation-like events take place in the neocortex for maintenance of CTA memory trace and that BDNF is an essential component of these processes. PMID:21960964

  19. Altering length and velocity feedback during a neuro-musculoskeletal simulation of normal gait contributes to hemiparetic gait characteristics.

    Jansen, Karen; De Groote, Friedl; Aerts, Wouter; De Schutter, Joris; Duysens, Jacques; Jonkers, Ilse

    2014-04-30

    Spasticity is an important complication after stroke, especially in the anti-gravity muscles, i.e. lower limb extensors. However the contribution of hyperexcitable muscle spindle reflex loops to gait impairments after stroke is often disputed. In this study a neuro-musculoskeletal model was developed to investigate the contribution of an increased length and velocity feedback and altered reflex modulation patterns to hemiparetic gait deficits. A musculoskeletal model was extended with a muscle spindle model providing real-time length and velocity feedback of gastrocnemius, soleus, vasti and rectus femoris during a forward dynamic simulation (neural control model). By using a healthy subject's base muscle excitations, in combination with increased feedback gains and altered reflex modulation patterns, the effect on kinematics was simulated. A foot-ground contact model was added to account for the interaction effect between the changed kinematics and the ground. The qualitative effect i.e. the directional effect and the specific gait phases where the effect is present, on the joint kinematics was then compared with hemiparetic gait deviations reported in the literature. Our results show that increased feedback in combination with altered reflex modulation patterns of soleus, vasti and rectus femoris muscle can contribute to excessive ankle plantarflexion/inadequate dorsiflexion, knee hyperextension/inadequate flexion and increased hip extension/inadequate flexion during dedicated gait cycle phases. Increased feedback of gastrocnemius can also contribute to excessive plantarflexion/inadequate dorsiflexion, however in combination with excessive knee and hip flexion. Increased length/velocity feedback can therefore contribute to two types of gait deviations, which are both in accordance with previously reported gait deviations in hemiparetic patients. Furthermore altered modulation patterns, in particular the reduced suppression of the muscle spindle feedback during

  20. A Portable Gait Asymmetry Rehabilitation System for Individuals with Stroke Using a Vibrotactile Feedback

    Muhammad Raheel Afzal

    2015-01-01

    Full Text Available Gait asymmetry caused by hemiparesis results in reduced gait efficiency and reduced activity levels. In this paper, a portable rehabilitation device is proposed that can serve as a tool in diagnosing gait abnormalities in individuals with stroke and has the capability of providing vibration feedback to help compensate for the asymmetric gait. Force-sensitive resistor (FSR based insoles are used to detect ground contact and estimate stance time. A controller (Arduino provides different vibration feedback based on the gait phase measurement. It also allows wireless interaction with a personal computer (PC workstation using the XBee transceiver module, featuring data logging capabilities for subsequent analysis. Walking trials conducted with healthy young subjects allowed us to observe that the system can influence abnormality in the gait. The results of trials showed that a vibration cue based on temporal information was more effective than intensity information. With clinical experiments conducted for individuals with stroke, significant improvement in gait symmetry was observed with minimal disturbance caused to the balance and gait speed as an effect of the biofeedback. Future studies of the long-term rehabilitation effects of the proposed system and further improvements to the system will result in an inexpensive, easy-to-use, and effective rehabilitation device.

  1. Time course of protein synthesis-dependent phase of olfactory memory in the cricket Gryllus bimaculatus.

    Matsumoto, Yukihisa; Noji, Sumihare; Mizunami, Makoto

    2003-04-01

    The cricket Gryllus bimaculatus forms a stable olfactory memory that lasts for practically a lifetime. As a first step to elucidate the cellular mechanisms of olfactory learning and memory retention in crickets, we studied the dependency of memory retention on the de novo brain protein synthesis by injecting the protein synthesis inhibitor cycloheximide (CHX) into the head capsule. Injection of CHX inhibited (3)H-leucine incorporation into brain proteins by > 90% for 3 hr. Crickets were trained to associate peppermint odor with water (reward) and vanilla odor with saline solution (non-reward) and were injected with CHX before or at different times after training. Their odor preferences were tested at 2 hr, 1 day and 4 days after training. Memory retention at 2 hr after training was unaffected by CHX injection. However, the level of retention at 1 day and 4 days after training was lowered when CHX was injected 1 hour before training or at 1 hr or 6 hr after training. To study the time course of the development of CHX-sensitive memory phase, crickets that had been injected with CHX at 1 hr after training were tested at different times from 2 to 12 hr after training. The level of retention was unaffected up to 4 hr after training but significantly lowered at 5 hr after training, and the CHX-sensitive memory phase developed gradually during the next several hours. CHX dissociates two phases of olfactory memory in crickets: earlier protein synthesis-independent phase ( 5 hr) protein synthesis-dependent phase.

  2. GaitKeeper: A System for Measuring Canine Gait

    Cassim Ladha

    2017-02-01

    Full Text Available It is understood gait has the potential to be used as a window into neurodegenerative disorders, identify markers of subclinical pathology, inform diagnostic algorithms of disease progression and measure the efficacy of interventions. Dogs’ gaits are frequently assessed in a veterinary setting to detect signs of lameness. Despite this, a reliable, affordable and objective method to assess lameness in dogs is lacking. Most described canine lameness assessments are subjective, unvalidated and at high risk of bias. This means reliable, early detection of canine gait abnormalities is challenging, which may have detrimental implications for dogs’ welfare. In this paper, we draw from approaches and technologies used in human movement science and describe a system for objectively measuring temporal gait characteristics in dogs (step-time, swing-time, stance-time. Asymmetries and variabilities in these characteristics are of known clinical significance when assessing lameness but presently may only be assessed on coarse scales or under highly instrumented environments. The system consists an inertial measurement unit, containing a 3-axis accelerometer and gyroscope coupled with a standardized walking course. The measurement unit is attached to each leg of the dog under assessment before it is walked around the course. The data by the measurement unit is then processed to identify steps and subsequently, micro-gait characteristics. This method has been tested on a cohort of 19 healthy dogs of various breeds ranging in height from 34.2 cm to 84.9 cm. We report the system as capable of making precise step delineations with detections of initial and final contact times of foot-to-floor to a mean precision of 0.011 s and 0.048 s, respectively. Results are based on analysis of 12,678 foot falls and we report a sensitivity, positive predictive value and F-score of 0.81, 0.83 and 0.82 respectively. To investigate the effect of gait on system performance

  3. Multiple gait parameters derived from iPod accelerometry predict age-related gait changes

    Kosse, Nienke; Vuillerme, Nicolas; Hortobagyi, Tibor; Lamoth, Claude

    Introduction Normative data of how natural aging affects gait can serve as a frame of reference for changes in gait dynamics due to pathologies. Therefore, the present study aims (1) to identify gait variables sensitive to age-related changes in gait over the adult life span using the iPod and (2)

  4. [EEG alpha indices in dependence on the menstrual cycle phase and salivary progesterone].

    Bazanova, O M; Kondratenko, A V; Kuz'minova, O I; Muravleva, K B; Petrova, S E

    2014-01-01

    The effects of the neurohumoral status on the EEG alpha - activity indices were studied in a within-subject design with 78 women aged 18-27 years during 1-2 menstrual cycle. Psychometric and EEG indices of alpha waves basal body temperature, saliva progesterone and cortisol level were monitored every 2-3 days. Menstrual and follicular recording sessions occurred before the ovulatory temperature rise, luteal recording session--after increasing progesterone level more than 20% respect to previous day and premenstrual sessions after decreasing progesterone level more that 20% respect to previous day. The design consisted of rest and task periods EEG, EMG and ECG recordings. Half the subjects began during their menstrual phase and half began during their luteal phase. All 5 phases were compared for differences between psychometric features EEG alpha activity, EMG and ECG baseline resting levels, as well as for reactivity to cognitive task. The results showed menstrual phase differences in all psychometric and alpha EEG indices. The cognitive fluency, alpha peak frequency, alpha band width, power in alpha-2 frequency range are maximal at luteal, alpha visual activation and reactivity to cognitive task performance--at follicular phase. The hypothesis that the EEG alpha activity depends on the hormonal status supported by the positive association salivary progesterone level with the alpha peak frequency, power in the alpha-2 band and negative--with the power of the alpha-1 band. According these results, we conclude that psycho-physiological recording sessions with women might be provided with a glance to phase of menstrual cycle.

  5. Berry phase dependent quantum trajectories of electron-hole pairs in semiconductors under intense terahertz fields

    Yang, Fan; Liu, Ren-Bao

    2013-03-01

    Quantum evolution of particles under strong fields can be approximated by the quantum trajectories that satisfy the stationary phase condition in the Dirac-Feynmann path integrals. The quantum trajectories are the key concept to understand strong-field optics phenomena, such as high-order harmonic generation (HHG), above-threshold ionization (ATI), and high-order terahertz siedeband generation (HSG). The HSG in semiconductors may have a wealth of physics due to the possible nontrivial ``vacuum'' states of band materials. We find that in a spin-orbit-coupled semiconductor, the cyclic quantum trajectories of an electron-hole pair under a strong terahertz field accumulates nontrivial Berry phases. We study the monolayer MoS2 as a model system and find that the Berry phases are given by the Faraday rotation angles of the pulse emission from the material under short-pulse excitation. This result demonstrates an interesting Berry phase dependent effect in the extremely nonlinear optics of semiconductors. This work is supported by Hong Kong RGC/GRF 401512 and the CUHK Focused Investments Scheme.

  6. Mutual information and phase dependencies: measures of reduced nonlinear cardiorespiratory interactions after myocardial infarction.

    Hoyer, Dirk; Leder, Uwe; Hoyer, Heike; Pompe, Bernd; Sommer, Michael; Zwiener, Ulrich

    2002-01-01

    The heart rate variability (HRV) is related to several mechanisms of the complex autonomic functioning such as respiratory heart rate modulation and phase dependencies between heart beat cycles and breathing cycles. The underlying processes are basically nonlinear. In order to understand and quantitatively assess those physiological interactions an adequate coupling analysis is necessary. We hypothesized that nonlinear measures of HRV and cardiorespiratory interdependencies are superior to the standard HRV measures in classifying patients after acute myocardial infarction. We introduced mutual information measures which provide access to nonlinear interdependencies as counterpart to the classically linear correlation analysis. The nonlinear statistical autodependencies of HRV were quantified by auto mutual information, the respiratory heart rate modulation by cardiorespiratory cross mutual information, respectively. The phase interdependencies between heart beat cycles and breathing cycles were assessed basing on the histograms of the frequency ratios of the instantaneous heart beat and respiratory cycles. Furthermore, the relative duration of phase synchronized intervals was acquired. We investigated 39 patients after acute myocardial infarction versus 24 controls. The discrimination of these groups was improved by cardiorespiratory cross mutual information measures and phase interdependencies measures in comparison to the linear standard HRV measures. This result was statistically confirmed by means of logistic regression models of particular variable subsets and their receiver operating characteristics.

  7. Anomalous interfacial tension temperature dependence of condensed phase drops in magnetic fluids

    Ivanov, Aleksey S.

    2018-05-01

    Interfacial tension temperature dependence σ(T) of the condensed phase (drop-like aggregates) in magnetic fluids undergoing field induced phase transition of the "gas-liquid" type was studied experimentally. Numerical analysis of the experimental data has revealed the anomalous (if compared to ordinary one-component fluids) behavior of the σ(T) function for all tested magnetic colloid samples: the condensed phase drops at high T ≈ 75 C exhibit higher σ(T) than the drops condensed at low T ≈ 20 C. The σ(T) behavior is explained by the polydispersity of magnetic colloids: at high T, only the largest colloidal particles are able to take part in the field induced condensation; thus, the increase of T causes the growth of the average particle diameters inside the drop-like aggregates, what in its turn results in the growth of σ(T). The result is confirmed by qualitative theoretical estimations and qualitative experimental observation of the condensed phase "evaporation" process after the applied magnetic field is removed: the drops that are formed due to capillary instability of the drop-like aggregates retract by one order of magnitude faster at high T, and the evaporation of the drops slows down at high T.

  8. Symmetry Analysis of Gait between Left and Right Limb Using Cross-Fuzzy Entropy

    Yi Xia

    2016-01-01

    Full Text Available The purpose of this paper is the investigation of gait symmetry problem by using cross-fuzzy entropy (C-FuzzyEn, which is a recently proposed cross entropy that has many merits as compared to the frequently used cross sample entropy (C-SampleEn. First, we used several simulation signals to test its performance regarding the relative consistency and dependence on data length. Second, the gait time series of the left and right stride interval were used to calculate the C-FuzzyEn values for gait symmetry analysis. Besides the statistical analysis, we also realized a support vector machine (SVM classifier to perform the classification of normal and abnormal gaits. The gait dataset consists of 15 patients with Parkinson’s disease (PD and 16 control (CO subjects. The results show that the C-FuzzyEn values of the PD patients’ gait are significantly higher than that of the CO subjects with a p value of less than 10-5, and the best classification performance evaluated by a leave-one-out (LOO cross-validation method is an accuracy of 96.77%. Such encouraging results imply that the C-FuzzyEn-based gait symmetry measure appears as a suitable tool for analyzing abnormal gaits.

  9. Tradeoff analysis for Dependable Real-Time Embedded Systems during the Early Design Phases

    Gan, Junhe

    Embedded systems are becoming increasingly complex and have tight competing constraints in terms of performance, cost, energy consumption, dependability, flexibility, security, etc. The objective of this thesis is to propose design methods and tools for supporting the tradeoff analysis of competing...... to processing elements, as well as the processor voltage and frequency levels for executing each task, such that transient faults are tolerated, the real-time constraints of the application are satisfied, and the energy consumed is minimized. In this thesis, we target the early design phases, when decisions...... have a high impact on the subsequent implementation choices. However, due to a lack of information, the early design phases are characterized by uncertainties, e.g., in the worst-case execution times (WCETs), in the functionality requirements, or in the hardware component costs. In this context, we...

  10. The Wavelength Dependence of the Lunar Phase Curve as Seen by the LRO LAMP

    Liu, Y.; Retherford, K. D.; Greathouse, T. K.; Hendrix, A. R.; Mandt, K.; Gladstone, R.; Cahill, J. T.; Egan, A.; Kaufmann, D. E.; Grava, C.; Pryor, W. R.

    2016-12-01

    The Lunar Reconnaissance Orbiter (LRO) Lyman Alpha Mapping Project (LAMP) provides global coverage of both nightside and dayside of the Moon in the far ultraviolet (FUV) wavelengths. The nightside observations use roughly uniform diffuse illumination sources from interplanetary medium Lyman-α sky glow and UV-bright stars so that traditional photometric corrections do not apply. In contrast, the dayside observations use sunlight as its illumination source where bidirectional reflectance is measured. The bidirectional reflectance is dependent on the incident, emission, and phase angles as well as the soil properties. Thus the comparisons of dayside mapping and nightside mapping techniques offer a method for cross-comparing the photometric correction factors because the observations are made under different lighting and viewing conditions. Specifically, the nightside data well constrain the single-scattering coefficient. We'll discuss the wavelength dependence of the lunar phase curve as seen by the LAMP instrument in dayside data. Our preliminary results indicate that the reflectance in the FUV wavelengths decreases with the increasing phase angles from 0° to 90°, similar to the phase curve in the UV-visible wavelengths as studied by Hapke et al. (2012) using LRO wide angle camera (WAC) data, among other visible-wavelength lunar studies. Particularly, we'll report how coherent backscattering and shadow hiding contribute to the opposition surge, given the fact that the albedo at FUV wavelengths is extremely low and thus multiple scattering is significantly less important. Finally, we'll report the derived Hapke parameters at FUV wavelengths for our study areas.

  11. NMDA-dependent phase synchronization between septal and temporal CA3 hippocampal networks.

    Gu, Ning; Jackson, Jesse; Goutagny, Romain; Lowe, Germaine; Manseau, Frédéric; Williams, Sylvain

    2013-05-08

    Increasing evidence suggests that synchronization between brain regions is essential for information exchange and memory processes. However, it remains incompletely known which synaptic mechanisms contribute to the process of synchronization. Here, we investigated whether NMDA receptor-mediated synaptic plasticity was an important player in synchronization between septal and temporal CA3 areas of the rat hippocampus. We found that both the septal and temporal CA3 regions intrinsically generate weakly synchronized δ frequency oscillations in the complete hippocampus in vitro. Septal and temporal oscillators differed in frequency, power, and rhythmicity, but both required GABAA and AMPA receptors. NMDA receptor activation, and most particularly the NR2B subunit, contributed considerably more to rhythm generation at the temporal than the septal region. Brief activation of NMDA receptors by application of extracellular calcium dramatically potentiated the septal-temporal coherence for long durations (>40 min), an effect blocked by the NMDA antagonist AP-5. This long-lasting NMDA-receptor-dependent increase in coherence was also associated with an elevated phase locking of spikes locally and across regions. Changes in coherence between oscillators were associated with increases in phase locking between oscillators independent of oscillator amplitude. Finally, although the septal CA3 rhythm preceded the oscillations in temporal regions in control conditions, this was reversed during the NMDA-dependent enhancement in coherence, suggesting that NMDA receptor activation can change the direction of information flow along the septotemporal CA3 axis. These data demonstrate that plastic changes in communication between septal and temporal hippocampal regions can arise from the NMDA-dependent phase locking of neural oscillators.

  12. Is P-glycoprotein (ABCB1) a phase 0 or a phase 3 colchicine transporter depending on colchicine exposure conditions?

    Decleves, Xavier.; Niel, Elisabeth; Debray, Marcel; Scherrmann, Jean-Michel

    2006-01-01

    This study investigates the P-glycoprotein (Pgp)-mediated transport of its substrates in accumulation or efflux modes under steady-state conditions. The kinetics of colchicine uptake and efflux, a substrate of both Pgp and intracellular tubulin, were studied in HL60 and HL60/DNR cells; HL60/DNR cells contain 25 times more Pgp than do HL60 cells. HL60/DNR cells in a medium containing 6.25 nM colchicine, which mimics therapeutic conditions, reached steady-state twice as rapidly as did HL60 cells, and accumulated 24-times less colchicine than did HL60 cells. The Pgp inhibitor GF120918, increased colchicine uptake by HL60 cells 1.2-fold and that of HL60/DNR cells 17-fold, while it had no effect on colchicine efflux from either cell line that had been incubated with colchicine for 24 h. Colchicine kinetics fitted well a two closed-compartment model, showing that the low intracellular accumulation of colchicine in HL60/DNR cells resulted from a 11-fold decrease in colchicine uptake and a 2.3-fold increase in colchicine efflux, that could be attributed to Pgp-mediated efflux activity in HL60/DNR cells. Intracellular colchicine was mainly and similarly distributed in the cytosol in both cell lines. These data demonstrate that the kinetics of the intracellular colchicine accumulation depend on the density of Pgp and that Pgp is more a phase 0 (preventing cellular uptake) than a phase 3 (effluxing intracellular substrate) transporter under steady-state conditions, although the situation is reversed after a short incubation time (30 min), when intracellular free colchicine concentration is probably high enough for it to be removed from the cell by Pgp

  13. Gait analysis in demented subjects: Interests and perspectives

    Olivier Beauchet

    2008-03-01

    Full Text Available Olivier Beauchet1, Gilles Allali2, Gilles Berrut3, Caroline Hommet4, Véronique Dubost5, Frédéric Assal21Department of Geriatrics, Angers University Hospital, France; 2Department of Neurology, Geneva University Hospital, France; 3Department of Geriatrics, Nantes University Hospital, France; 4Department of Internal Medicine and Geriatrics, Tours University Hospital, France; 5Department of Geriatrics, Dijon University Hospital, FranceAbstract: Gait disorders are more prevalent in dementia than in normal aging and are related to the severity of cognitive decline. Dementia-related gait changes (DRGC mainly include decrease in walking speed provoked by a decrease in stride length and an increase in support phase. More recently, dual-task related changes in gait were found in Alzheimer’s disease (AD and non-Alzheimer dementia, even at an early stage. An increase in stride-to-stride variability while usual walking and dual-tasking has been shown to be more specific and sensitive than any change in mean value in subjects with dementia. Those data show that DRGC are not only associated to motor disorders but also to problem with central processing of information and highlight that dysfunction of temporal and frontal lobe may in part explain gait impairment among demented subjects. Gait assessment, and more particularly dual-task analysis, is therefore crucial in early diagnosis of dementia and/or related syndromes in the elderly. Moreover, dual-task disturbances could be a specific marker of falling at a pre-dementia stage.Keywords: gait, prediction of dementia, risk of falling, older adult

  14. NEAs: Phase Angle Dependence of Asteroid Class and Diameter from Observational Studies

    Wooden, Diane H.; Lederer, Susan M.; Bus, Schlete; Tokunaga, Alan; Jehin, Emmanuel; Howell, Ellen S.; Nolan, Michael C.; Ryan, Erin; Fernandez, Yan; Harker, David; hide

    2015-01-01

    We will discuss the results of a planned observation campaign of Near Earth Asteroids (NEAs), 1999 CU3, 2002 GM2, 2002 FG7, and 3691 Bede with instruments on the United Kingdom Infrared Telescope (UKIRT) from 15-Mar-2015 to 28-April 2015 UT. We will study the phase-angle dependence of the reflectance and thermal emission spectra. Recent publications reveal that the assignment of the asteroid class from visible and near-IR spectroscopy can change with phase angle for NEAs with silicate-bearing minerals on their surfaces (S-class asteroids) (Thomas et al. 2014, Icarus 228, 217; Sanchez et al. 2012 Icarus 220, 36). Only three of the larger NEAs have been measured at a dozen phase angles and the trends are not all the same, so there is not yet enough information to create a phase-angle correction. Also, the phase angle effect is not characterized well for the thermal emission including determination of the albedo and the thermal emission. The few NEAs were selected for our study amongst many possible targets based on being able to observe them through a wide range of phase angles, ranging from less than about 10 degrees to greater than 45 degrees over the constrained date range. The orbits of NEAs often generate short observing windows at phase angles higher than 45 deg (i.e., whizzing by Earth and/or close to dawn or dusk). Ultimately, lowering the uncertainty of the translation of asteroid class to meteorite analog and of albedo and size determinations are amongst our science goals. On a few specific nights, we plan to observe the 0.75-2.5 micron spectra with IRTF+SpeX for comparison with UKIRT data including 5-20 micron with UKIRT+UIST/Michelle to determine as best as possible the albedos. To ensure correct phasing of spectroscopic data, we augment with TRAPPIST-telescope light curves and R-band guider image data. Our observations will contribute to understanding single epoch mid-IR and near-IR measurements to obtain albedo, size and IR beaming parameters (the

  15. Noisy interlimb coordination can be a main cause of freezing of gait in patients with little to no parkinsonism.

    Takao Tanahashi

    Full Text Available Freezing of gait in patients with Parkinson's disease is associated with several factors, including interlimb incoordination and impaired gait cycle regulation. Gait analysis in patients with Parkinson's disease is confounded by parkinsonian symptoms such as rigidity. To understand the mechanisms underlying freezing of gait, we compared gait patterns during straight walking between 9 patients with freezing of gait but little to no parkinsonism (freezing patients and 11 patients with Parkinson's disease (non-freezing patients. Wireless sensors were used to detect foot contact and toe-off events, and the step phase of each foot contact was calculated by defining one stride cycle of the other leg as 360°. Phase-resetting analysis was performed, whereby the relation between the step phase of one leg and the subsequent phase change in the following step of the other leg was quantified using regression analysis. A small slope of the regression line indicates a forceful correction (phase reset at every step of the deviation of step phase from the equilibrium phase, usually at around 180°. The slope of this relation was smaller in freezing patients than in non-freezing patients, but the slope exhibited larger step-to-step variability. This indicates that freezing patients executed a forceful but noisy correction of the deviation of step phase, whereas non-freezing patients made a gradual correction of the deviation. Moreover, freezing patients tended to show more variable step phase and stride time than non-freezing patients. Dynamics of a model of two coupled oscillators interacting through a phase resetting mechanism were examined, and indicated that the deterioration of phase reset by noise provoked variability in step phase and stride time. That is, interlimb coordination can affect regulation of the gait cycle. These results suggest that noisy interlimb coordination, which probably caused forceful corrections of step phase deviation, can be a

  16. Skeleton-Based Abnormal Gait Detection

    Trong-Nguyen Nguyen

    2016-10-01

    Full Text Available Human gait analysis plays an important role in musculoskeletal disorder diagnosis. Detecting anomalies in human walking, such as shuffling gait, stiff leg or unsteady gait, can be difficult if the prior knowledge of such a gait pattern is not available. We propose an approach for detecting abnormal human gait based on a normal gait model. Instead of employing the color image, silhouette, or spatio-temporal volume, our model is created based on human joint positions (skeleton in time series. We decompose each sequence of normal gait images into gait cycles. Each human instant posture is represented by a feature vector which describes relationships between pairs of bone joints located in the lower body. Such vectors are then converted into codewords using a clustering technique. The normal human gait model is created based on multiple sequences of codewords corresponding to different gait cycles. In the detection stage, a gait cycle with normality likelihood below a threshold, which is determined automatically in the training step, is assumed as an anomaly. The experimental results on both marker-based mocap data and Kinect skeleton show that our method is very promising in distinguishing normal and abnormal gaits with an overall accuracy of 90.12%.

  17. Gait Stability in Children with Cerebral Palsy

    Bruijn, Sjoerd M.; Millard, Matthew; van Gestel, Leen; Meyns, Pieter; Jonkers, Ilse; Desloovere, Kaat

    2013-01-01

    Children with unilateral Cerebral Palsy (CP) have several gait impairments, amongst which impaired gait stability may be one. We tested whether a newly developed stability measure (the foot placement estimator, FPE) which does not require long data series, can be used to asses gait stability in typically developing (TD) children as well as…

  18. Experience-dependent phase-reversal of hippocampal neuron firing during REM sleep.

    Poe, G R; Nitz, D A; McNaughton, B L; Barnes, C A

    2000-02-07

    The idea that sleep could serve a cognitive function has remained popular since Freud stated that dreams were "not nonsense" but a time to sort out experiences [S. Freud, Letter to Wilhelm Fliess, May 1897, in The Origins of Psychoanalysis - Personal Letters of Sigmund Freud, M. Bonaparte, A. Freud, E. Kris (Eds.), Translated by E. Mosbacher, J. Strachey, Basic Books and Imago Publishing, 1954]. Rapid eye movement (REM) sleep, which is associated with dream reports, is now known to be is important for acquisition of some tasks [A. Karni, D. Tanne, B.S. Rubenstein, J.J.M. Askenasy, D. Sagi, Dependence on REM sleep of overnight improvement of a perceptual skill, Science 265 (1994) 679-682; C. Smith, Sleep states and learning: a review of the animal literature, Biobehav. Rev. 9 (1985) 157-168]; although why this is so remains obscure. It has been proposed that memories may be consolidated during REM sleep or that forgetting of unnecessary material occurs in this state [F. Crick, G. Mitchison, The function of dream sleep, Nature 304 (1983) 111-114; D. Marr, Simple memory: a theory for archicortex, Philos. Trans. R. Soc. B. 262 (1971) 23-81]. We studied the firing of multiple single neurons in the hippocampus, a structure that is important for episodic memory, during familiar and novel experiences and in subsequent REM sleep. Cells active in familiar places during waking exhibited a reversal of firing phase relative to local theta oscillations in REM sleep. Because firing-phase can influence whether synapses are strengthened or weakened [C. Holscher, R. Anwyl, M.J. Rowan, Stimulation on the positive phase of hippocampal theta rhythm induces long-term potentiation that can be depotentiated by stimulation on the negative phase in area CA1 in vivo, J. Neurosci. 15 (1977) 6470-6477; P.T. Huerta, J.E. Lisman, Bidirectional synaptic plasticity induced by a single burst during cholinergic theta oscillation in CA1 in vitro, Neuron 15 (1995) 1053-1063; C. Pavlides, Y

  19. Out-of-equilibrium dynamics driven by localized time-dependent perturbations at quantum phase transitions

    Pelissetto, Andrea; Rossini, Davide; Vicari, Ettore

    2018-03-01

    We investigate the quantum dynamics of many-body systems subject to local (i.e., restricted to a limited space region) time-dependent perturbations. If the system crosses a quantum phase transition, an off-equilibrium behavior is observed, even for a very slow driving. We show that, close to the transition, time-dependent quantities obey scaling laws. In first-order transitions, the scaling behavior is universal, and some scaling functions can be computed exactly. For continuous transitions, the scaling laws are controlled by the standard critical exponents and by the renormalization-group dimension of the perturbation at the transition. Our protocol can be implemented in existing relatively small quantum simulators, paving the way for a quantitative probe of the universal off-equilibrium scaling behavior, without the need to manipulate systems close to the thermodynamic limit.

  20. An improved stochastic algorithm for temperature-dependent homogeneous gas phase reactions

    Kraft, M

    2003-01-01

    We propose an improved stochastic algorithm for temperature-dependent homogeneous gas phase reactions. By combining forward and reverse reaction rates, a significant gain in computational efficiency is achieved. Two modifications of modelling the temperature dependence (with and without conservation of enthalpy) are introduced and studied quantitatively. The algorithm is tested for the combustion of n-heptane, which is a reference fuel component for internal combustion engines. The convergence of the algorithm is studied by a series of numerical experiments and the computational cost of the stochastic algorithm is compared with the DAE code DASSL. If less accuracy is needed the stochastic algorithm is faster on short simulation time intervals. The new stochastic algorithm is significantly faster than the original direct simulation algorithm in all cases considered.

  1. Deviations in gait metrics in patients with chronic ankle instability: a case control study.

    Gigi, Roy; Haim, Amir; Luger, Elchanan; Segal, Ganit; Melamed, Eyal; Beer, Yiftah; Nof, Matityahu; Nyska, Meir; Elbaz, Avi

    2015-01-01

    Gait metric alterations have been previously reported in patients suffering from chronic ankle instability (CAI). Previous studies of gait in this population have been comprised of relatively small cohorts, and the findings of these studies are not uniform. The objective of the present study was to examine spatiotemporal gait metrics in patients with CAI and examine the relationship between self-reported disease severity and the magnitude of gait abnormalities. Forty-four patients with CAI were identified and compared to 53 healthy controls. Patients were evaluated with spatiotemporal gait analysis via a computerized mat and with the Short Form (SF) - 36 health survey. Patients with CAI were found to walk with approximately 16% slower walking velocity, 9% lower cadence and approximately 7% lower step length. Furthermore, the base of support, during walking, in the CAI group was approximately 43% wider, and the single limb support phase was 3.5% shorter compared to the control group. All of the SF-36 8-subscales, as well as the SF-36 physical component summary and SF-36 mental component summary, were significantly lower in patients with CAI compared to the control group. Finally, significant correlations were found between most of the objective gait measures and the SF-36 mental component summary and SF-36 physical component summary. The results outline a gait profile for patients suffering from CAI. Significant differences were found in most spatiotemporal gait metrics. An important finding was a significantly wider base of support. It may be speculated that these gait alterations may reflect a strategy to deal with imbalance and pain. These findings suggest the usefulness of gait metrics, alongside with the use of self-evaluation questionnaires, in assessing disease severity of patients with CAI.

  2. Gait characteristics after gait-oriented rehabilitation in chronic stroke.

    Peurala, Sinikka H; Titianova, Ekaterina B; Mateev, Plamen; Pitkänen, Kauko; Sivenius, Juhani; Tarkka, Ina M

    2005-01-01

    To assess the effects of rehabilitation in thirty-seven ambulatory patients with chronic stroke during three weeks in-patient rehabilitation period. In the intervention group, each patient received 75 min physiotherapy daily every workday including 20 minutes in the electromechanical gait trainer with body-weight support (BWS). In the control group, each patient participated in 45 min conventional physiotherapy daily. Motor ability was assessed with the first five items of the Modified Motor Assessment Scale (MMAS1-5) and ten meters walking speed. Spatio-temporal gait characteristics were recorded with an electrical walkway. The MMAS1-5 (pgait characteristics improved only in the intervention group, as seen in increased Functional Ambulation Profile score (p=0.023), velocity (p=0.023), the step lengths (affected side, p=0.011, non-affected side p=0.040), the stride lengths (p=0.018, p=0.006) and decreased step-time differential (p=0.043). Furthermore, all gait characteristics and other motor abilities remained in the discharge level at the six months in the intervention group. It appears that BWS training gives a long-lasting benefit in gait qualities even in chronic stroke patients.

  3. Single particle nonlocality, geometric phases and time-dependent boundary conditions

    Matzkin, A.

    2018-03-01

    We investigate the issue of single particle nonlocality in a quantum system subjected to time-dependent boundary conditions. We discuss earlier claims according to which the quantum state of a particle remaining localized at the center of an infinite well with moving walls would be specifically modified by the change in boundary conditions due to the wall’s motion. We first prove that the evolution of an initially localized Gaussian state is not affected nonlocally by a linearly moving wall: as long as the quantum state has negligible amplitude near the wall, the boundary motion has no effect. This result is further extended to related confined time-dependent oscillators in which the boundary’s motion is known to give rise to geometric phases: for a Gaussian state remaining localized far from the boundaries, the effect of the geometric phases is washed out and the particle dynamics shows no traces of a nonlocal influence that would be induced by the moving boundaries.

  4. Prominin-2 expression increases protrusions, decreases caveolae and inhibits Cdc42 dependent fluid phase endocytosis

    Singh, Raman Deep, E-mail: Takhter.Ramandeep@mayo.edu; Schroeder, Andreas S.; Scheffer, Luana; Holicky, Eileen L.; Wheatley, Christine L.; Marks, David L., E-mail: Marks.david@mayo.edu; Pagano, Richard E.

    2013-05-10

    Highlights: •Prominin-2 expression induced protrusions that co-localized with lipid raft markers. •Prominin-2 expression decreased caveolae, caveolar endocytosis and increased pCav1. •Prominin-2 expression inhibited fluid phase endocytosis by inactivation of Cdc42. •These endocytic effects can be reversed by adding exogenous cholesterol. •Caveolin1 knockdown restored fluid phase endocytosis in Prominin2 expressing cells. -- Abstract: Background: Membrane protrusions play important roles in biological processes such as cell adhesion, wound healing, migration, and sensing of the external environment. Cell protrusions are a subtype of membrane microdomains composed of cholesterol and sphingolipids, and can be disrupted by cholesterol depletion. Prominins are pentaspan membrane proteins that bind cholesterol and localize to plasma membrane (PM) protrusions. Prominin-1 is of great interest as a marker for stem and cancer cells, while Prominin-2 (Prom2) is reportedly restricted to epithelial cells. Aim: To characterize the effects of Prom-2 expression on PM microdomain organization. Methods: Prom2-fluorescent protein was transfected in human skin fibroblasts (HSF) and Chinese hamster ovary (CHO) cells for PM raft and endocytic studies. Caveolae at PM were visualized using transmission electron microscopy. Cdc42 activation was measured and caveolin-1 knockdown was performed using siRNAs. Results: Prom2 expression in HSF and CHO cells caused extensive Prom2-positive protrusions that co-localized with lipid raft markers. Prom2 expression significantly decreased caveolae at the PM, reduced caveolar endocytosis and increased caveolin-1 phosphorylation. Prom2 expression also inhibited Cdc42-dependent fluid phase endocytosis via decreased Cdc42 activation. Effects on endocytosis were reversed by addition of cholesterol. Knockdown of caveolin-1 by siRNA restored Cdc42 dependent fluid phase endocytosis in Prom2-expressing cells. Conclusions: Prom2 protrusions primarily

  5. Change in gait after high tibial osteotomy: A systematic review and meta-analysis.

    Lee, Seung Hoon; Lee, O-Sung; Teo, Seow Hui; Lee, Yong Seuk

    2017-09-01

    We conducted a meta-analysis to analyze how high tibial osteotomy (HTO) changes gait and focused on the following questions: (1) How does HTO change basic gait variables? (2) How does HTO change the gait variables in the knee joint? Twelve articles were included in the final analysis. A total of 383 knees was evaluated. There were 237 open wedge (OW) and 143 closed wedge (CW) HTOs. There were 4 level II studies and 8 level III studies. All studies included gait analysis and compared pre- and postoperative values. One study compared CWHTO and unicompartmental knee arthroplasty (UKA), and another study compared CWHTO and OWHTO. Five studies compared gait variables with those of healthy controls. One study compared operated limb gait variables with those in the non-operated limb. Gait speed, stride length, knee adduction moment, and lateral thrust were major variables assessed in 2 or more studies. Walking speed increased and stride length was increased or similar after HTO compared to the preoperative value in basic gait variables. Knee adduction moment and lateral thrust were decreased after HTO compared to the preoperative knee joint gait variables. Change in co-contraction of the medial side muscle after surgery differed depending on the degree of frontal plane alignment. The relationship between change in knee adduction moment and change in mechanical axis angle was controversial. Based on our systematic review and meta-analysis, walking speed and stride length increased after HTO. Knee adduction moment and lateral thrust decreased after HTO compared to the preoperative values of gait variables in the knee joint. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Poor Gait Performance and Prediction of Dementia: Results From a Meta-Analysis.

    Beauchet, Olivier; Annweiler, Cédric; Callisaya, Michele L; De Cock, Anne-Marie; Helbostad, Jorunn L; Kressig, Reto W; Srikanth, Velandai; Steinmetz, Jean-Paul; Blumen, Helena M; Verghese, Joe; Allali, Gilles

    2016-06-01

    Poor gait performance predicts risk of developing dementia. No structured critical evaluation has been conducted to study this association yet. The aim of this meta-analysis was to systematically examine the association of poor gait performance with incidence of dementia. An English and French Medline search was conducted in June 2015, with no limit of date, using the medical subject headings terms "Gait" OR "Gait Disorders, Neurologic" OR "Gait Apraxia" OR "Gait Ataxia" AND "Dementia" OR "Frontotemporal Dementia" OR "Dementia, Multi-Infarct" OR "Dementia, Vascular" OR "Alzheimer Disease" OR "Lewy Body Disease" OR "Frontotemporal Dementia With Motor Neuron Disease" (Supplementary Concept). Poor gait performance was defined by standardized tests of walking, and dementia was diagnosed according to international consensus criteria. Four etiologies of dementia were identified: any dementia, Alzheimer disease (AD), vascular dementia (VaD), and non-AD (ie, pooling VaD, mixed dementias, and other dementias). Fixed effects meta-analyses were performed on the estimates in order to generate summary values. Of the 796 identified abstracts, 12 (1.5%) were included in this systematic review and meta-analysis. Poor gait performance predicted dementia [pooled hazard ratio (HR) combined with relative risk and odds ratio = 1.53 with P analysis provides evidence that poor gait performance predicts dementia. This association depends on the type of dementia; poor gait performance is a stronger predictor of non-AD dementias than AD. Copyright © 2016 AMDA – The Society for Post-Acute and Long-Term Care Medicine. Published by Elsevier Inc. All rights reserved.

  7. Invariant Classification of Gait Types

    Fihl, Preben; Moeslund, Thomas B.

    2008-01-01

    . Input silhouettes are matched to the database using the Hungarian method. A classifier is defined based on the dissimilarity between the input silhouettes and the gait actions of the database. The overall recognition rate is 88.2% on a large and diverse test set. The recognition rate is better than...

  8. Gait variability and motor control in people with knee osteoarthritis.

    Alkjaer, Tine; Raffalt, Peter C; Dalsgaard, Helle; Simonsen, Erik B; Petersen, Nicolas C; Bliddal, Henning; Henriksen, Marius

    2015-10-01

    Knee osteoarthritis (OA) is a common disease that impairs walking ability and function. We compared the temporal gait variability and motor control in people with knee OA with healthy controls. The purpose was to test the hypothesis that the temporal gait variability would reflect a more stereotypic pattern in people with knee OA compared with healthy age-matched subjects. To assess the gait variability the temporal structure of the ankle and knee joint kinematics was quantified by the largest Lyapunov exponent and the stride time fluctuations were quantified by sample entropy and detrended fluctuation analysis. The motor control was assessed by the soleus (SO) Hoffmann (H)-reflex modulation and muscle co-activation during walking. The results showed no statistically significant mean group differences in any of the gait variability measures or muscle co-activation levels. The SO H-reflex amplitude was significantly higher in the knee OA group around heel strike when compared with the controls. The mean group difference in the H-reflex in the initial part of the stance phase (control-knee OA) was -6.6% Mmax (95% CI: -10.4 to -2.7, p=0.041). The present OA group reported relatively small impact of their disease. These results suggest that the OA group in general sustained a normal gait pattern with natural variability but with suggestions of facilitated SO H-reflex in the swing to stance phase transition. We speculate that the difference in SO H-reflex modulation reflects that the OA group increased the excitability of the soleus stretch reflex as a preparatory mechanism to avoid sudden collapse of the knee joint which is not uncommon in knee OA. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. An electromechanical gait trainer for restoration of gait in hemiparetic stroke patients: preliminary results.

    Hesse, S; Werner, C; Uhlenbrock, D; von Frankenberg, S; Bardeleben, A; Brandl-Hesse, B

    2001-01-01

    Modern concepts of gait rehabilitation after stroke favor a task-specific repetitive approach. In practice, the required physical effort of the therapists limits the realization of this approach. Therefore, a mechanized gait trainer enabling nonambulatory patients to have the repetitive practice of a gait-like movement without overstraining therapists was constructed. This preliminary study investigated whether an additional 4-week daily therapy on the gait trainer could improve gait ability in 14 chronic wheelchair-bound hemiparetic subjects. The 4 weeks of physiotherapy and gait-trainer therapy resulted in a relevant improvement of gait ability in all subjects. Velocity, cadence, and stride length improved significantly (p gait trainer seems feasible as an adjunctive tool in gait rehabilitation after stroke; further studies are needed.

  10. The Required Coefficient of Friction for evaluating gait alterations in people with Multiple Sclerosis during gait.

    Pacifici, Ilaria; Galli, Manuela; Kleiner, Ana Francisca Rozin; Corona, Federica; Coghe, Giancarlo; Marongiu, Elisabetta; Loi, Andrea; Crisafulli, Antonio; Cocco, Eleonora; Marrosu, Maria Giovanna; Pau, Massimiliano

    2016-11-01

    Required Coefficient of Friction (RCOF) is one of the most critical gait parameters associated to the occurrence of slipping in individuals affected by neurological disorders characterized by balance impairments. This study aims to calculate RCOF in people with Multiple Sclerosis (MS) on the basis of three-dimensional Gait Analysis (GA) data. This study enrolls 22 people with MS (pwMS) who were characterized by an Expanded Disability Status Score in the range 1.5-6 and 10 healthy controls (HC). All participants underwent to three-dimensional GA from which we extracted kinematic and kinetic data (i.e. the Ground Reaction Forces, GRF, and joint moments and powers in the sagittal plane). RCOF was calculated as the ratio of the shear to normal GRF components during the stance phase of gait cycle, and normalized by the walking velocity. Thus, the following variables were extracted: first peak (named P1COF), valley (named V1COF), and second peak (named P2COF) in RCOF curve; also computating the maximum ankle dorsi-plantarflexion moment (MOMmax) and the maximum ankle joint power (PWRmax). Our data revealed that P2COF results are significantly lower in pwMS when compared to HC (p=0.043; Z=-2.025). In pwMS, the study found a moderate, positive correlation between V1COF and MOMmax (r=0.558; pFriction during mid stance and push off phases is critically important to determine whether the frictional capabilities of foot/floor interface are sufficient to prevent slips in pwMS. The impaired ankle moment in MS group causes increased P2COF in comparison to HC, increasing the risk of slipping in the critical phase of transmission of the developed forces to kinematic chain. Also, the correlation analysis among RCOF values and kinetic variables describe the interplay between V1COF and MOMmax: the higher V1COF is, the higher is MOMmax; and the different correlation the study found between COF and kinetic parameters in MS and HC group highlightes the different gait patterns of the two

  11. An online gait generator for quadruped walking using motor primitives

    Chunlin Zhou

    2016-11-01

    Full Text Available This article presents implementation of an online gait generator on a quadruped robot. Firstly, the design of a quadruped robot is presented. The robot contains four leg modules each of which is constructed by a 2 degrees of freedom (2-DOF five-bar parallel linkage mechanism. Together with other two rotational DOF, the leg module is able to perform 4-DOF movement. The parallel mechanism of the robot allows all the servos attached on the body frame, so that the leg mass is decreased and motor load can be balanced. Secondly, an online gait generator based on dynamic movement primitives for the walking control is presented. Dynamic movement primitives provide an approach to generate periodic trajectories and they can be modulated in real time, which makes the online adjustment of walking gaits possible. This gait controller is tested by the quadruped robot in regulating walking speed, switching between forward\\backward movements and steering. The controller is easy to apply, expand and is quite effective on phase coordination and online trajectory modulation. Results of simulated experiments are presented.

  12. Effects of novel tubing gait on neuromuscular imbalance in cerebral palsy.

    Shin, Yoon Kyum; Lee, Dong Ryul; Kim, Do Hyun; Lee, Jae Jin; You, Sung Joshua Hyun; Yi, Chung Hwi; Jeon, Hye Seon

    2014-01-01

    Gait impairments from a neuromuscular imbalance are crucial issues in cerebral palsy. The purpose of our study was to compare the effects of the assistive tubing gait (ATG) and assistive-resistive tubing gait (ARTG) on improving the vasti and hamstring muscle imbalance during the initial contact to mid-stance phases in individuals with spastic diplegic cerebral palsy (CP). Fourteen age-matched individuals including seven normal individuals (11.7 years) and seven individuals with CP (12.9 years) were recruited. All participants underwent electromyography (EMG) measurement of the unilateral vasti and hamstring muscle activity during the three gait training conditions of no-tubing gait (NTG), ATG, and ARTG. A statistical one-way repeated-measure analysis of variance (ANOVA) was used to determine differences in the vasti and hamstring activity, the vasti/hamstring ratio, and the knee joint angle across the three gait training conditions for each group. The initial vasti and hamstring muscle imbalance in CP was significantly improved by applying the ARTG compared with the ATG. The vasti/hamstring ratio during the ARTG was compatible with the ratio value obtained from the NTG of normal individuals. The knee joint angle in CP was not improved in this short-term intervention. The ARTG proportionately increased the vasti activation and reciprocally inhibited the hamstring activity, subsequently improving the neuromuscular imbalance associated with the flexed-knee gait in individuals with spastic diplegic CP.

  13. Phase-dependent quantum interference between different pathways in bichromatic harmonic generation

    Jun, Cai; Li-Ming, Wang; Hao-Xue, Qiao

    2009-01-01

    This paper studies the harmonic generation of the hydrogen atom subjected to a collinear bichromatic laser field by numerically solving the time-dependent Schrödinger equation using the split-operator pseudo-spectral method. By adding a frequency variation to the additional field, the contributions of different pathways to particular order harmonic generation can be isolated. The quantum interference pattern between harmonic pathways, which influences the harmonic intensity, is found to be either constructive or destructive with respect to different relative phase of the two field components. Detailed description of up to the 35th-order harmonics and the harmonic pathways for a wide range of field parameters is presented. (atomic and molecular physics)

  14. Detection of second harmonic of phase dependence of superconducting current in Nb/Au/YBCO heterojunctions

    Komissinskij, F V; Ilichev, E V; Ivanov, Z G

    2001-01-01

    The results of the experimental study on the current phase dependence (CPD) of the heterotransitions, consisting of the niobium and the YBa sub 2 Cu sub 3 O sub x (YBCO) film with an additional interlayer from gold (Nb/Au/YBCO) are presented. The CPD measurement is carried out through the radiofrequency superconducting quantum interferometer. The CPD second harmonic is determined in the Nb/Au/YBCO heterotransitions. Possible causes of its appearance are discussed within the frames of the d +- s combined symmetry of the YBCO order parameter. One of the causes of the CPD second harmonic appearance is the twinning of the YBCO films (001). The second cause of existing the anomalously high critical current consists in the availability of the Nb/Au boundary with the transparence of approx 10 sup - sup 1 in the Nb/Au/YBCO

  15. Unsupervised learning by spike timing dependent plasticity in phase change memory (PCM synapses

    Stefano eAmbrogio

    2016-03-01

    Full Text Available We present a novel one-transistor/one-resistor (1T1R synapse for neuromorphic networks, based on phase change memory (PCM technology. The synapse is capable of spike-timing dependent plasticity (STDP, where gradual potentiation relies on set transition, namely crystallization, in the PCM, while depression is achieved via reset or amorphization of a chalcogenide active volume. STDP characteristics are demonstrated by experiments under variable initial conditions and number of pulses. Finally, we support the applicability of the 1T1R synapse for learning and recognition of visual patterns by simulations of fully connected neuromorphic networks with 2 or 3 layers with high recognition efficiency. The proposed scheme provides a feasible low-power solution for on-line unsupervised machine learning in smart reconfigurable sensors.

  16. Sensory feedback plays a significant role in generating walking gait and in gait transition in salamanders: A simulation study

    Nalin eHarischandra

    2011-11-01

    Full Text Available Here, we use a three-dimensional, neuro-musculo-mechanical model of a salamander with realistic physical parameters in order to investigate the role of sensory feedback in gait generation and transition. Activation of limb and axial muscles were driven by neural output patterns obtained from a central pattern generator (CPG which is composed of simulated spiking neurons with adaptation. The CPG consists of a body CPG and four limb CPGs that are interconnected via synapses both ipsilateraly and contralaterally. We use the model both with and without sensory modulation and for different combinations of ipsilateral and contralateral coupling between the limb CPGs. We found that the proprioceptive sensory inputs are essential in obtaining a coordinated walking gait. The sensory feedback includes the signals coming from the stretch receptor like intraspinal neurons located in the girdle regions and the limb stretch receptors residing in the hip and scapula regions of the salamander. On the other hand, coordinated motor output patterns for the trotting gait were obtainable without the sensory inputs. We found that the gait transition from walking to trotting can be induced by increased activity of the descending drive coming from the mesencephalic locomotor region (MLR and is helped by the sensory inputs at the hip and scapula regions detecting the late stance phase. More neurophysiological experiments are required to identify the precise type of mechanoreceptors in the salamander and the neural mechanisms mediating the sensory modulation.

  17. Effect of Duration of Disease on Gait Parameters in Parkinson’s Patients

    Aygün Özşahin

    2007-04-01

    Full Text Available OBJECTIVE: Posture and gait disturbances are major components which cause functional disability in Parkinson’s disease (PD. Three dimensional gait and motion analysis systems provide quantitative data of gait. OBJECTIVES: The aim of this study is to correlate between duration of disease and gait parameters of Parkinson patients during the on-phase. METHODS: We investigated temporospatial and kinematics variables of gait in 23 subjects with PD as measured in the on-phase of their medication cycle using motion analysis. We evaluated the correlation between all gait parameters and Gait and Balance Scale (GABS, unified Parkinson’s disease rating scale (UPDRS total-motor scores, Hoehn&Yahr (H&Y stages and duration of the disease. RESULTS: We found positive correlation between cadance and duration of disease. Patients had negative correlation between stride time and duration of disease. And also there was positive correlation between UPDRS total score and duration of disease. CONCLUSION: Increasing of cadance and decreasing of stride time exhibited by PD subjects is a compensatory mechanism for the difficulty in regulating stride lenght. It was reported that stride lenght control mediate by basal ganglia. Scaling of lower limb amplitude during locomotion can be controlled by higher levels of the Central Nervous System. Patients tend to increase pelvic rotation to keep their center of mass stabilised because of shortness of stride lenght. We thought that reduction pelvic and hip ROMs in coronal plane are impaired muscles of leg in the swing phase. These findings possibly indicate that shortness of stride lenght with the progression of disease is related to cortical centers. Three dimentional analysis systems provide detailed gait examination in PD patients to assess of progression and efficacy for therapies. Also, this method will guide us to explain physiopathologic mechanisms of PD

  18. The Effect of Two Different Cognitive Tests on Gait Parameters during Dual Tasks in Healthy Postmenopausal Women

    Magdalena Hagner-Derengowska

    2016-01-01

    Full Text Available Introduction. The paper aims to evaluate the influence of two different demanding cognitive tasks on gait parameters using BTS SMART system analysis. Patients and Methods. The study comprised 53 postmenopausal women aged 64.5 ± 6.7 years (range: 47–79. For every subject, gait analysis using a BTS SMART system was performed in a dual-task study design under three conditions: (I while walking only (single task, (II walking while performing a simultaneous simple cognitive task (SCT (dual task, and (III walking while performing a simultaneous complex cognitive task (CCT (dual task. Time-space parameters of gait pertaining to the length of a single support phase, double support phase, gait speed, step length, step width, and leg swing speed were analyzed. Results. Performance of cognitive tests during gait resulted in a statistically significant prolongation of the left (by 7% and right (by 7% foot gait cycle, shortening of the length of steps made with the right extremity (by 4%, reduction of speed of swings made with the left (by 11% and right (by 8% extremity, and reduction in gait speed (by 6%. Conclusions. Performance of cognitive tests during gait changes its individual pattern in relation to the level of the difficulty of the task.

  19. Volume dependence of T/sub c/ of Ternary A-15 Phases

    Shamrai, V.

    1984-01-01

    Results are presented of measurements of the superconducting transition temperature T/sub c/, lattice constant a, magnetic susceptibility /sub chi/, and critical field H/sub c/ 2 for many Nb 3 Al and V 3 Si-based ternary phases and Nb 3 SnH/sub x/. For V 3 Si-based ternary systems and Nb 3 SnH/sub x/ the density of states at the Fermi level N(epsilon/sub F/) sharply decreases with the concentration of the alloying element. The variation of N(epsilon/sub F/) in these ternary systems cannot be explained by the variation of a. In ternary phases Nb 3 (Al/sub 1-x/dY/sub x/), where Y can be Ge, Ga, Sb, or Se, a quite clear correlation is revealed between T/sub c/ and a. The dependence of T/sub c/ on V in these systems is due to the variation of the matrix element of the electron-phonon interaction 2 >

  20. Inverse size scaling of the nucleolus by a concentration-dependent phase transition.

    Weber, Stephanie C; Brangwynne, Clifford P

    2015-03-02

    Just as organ size typically increases with body size, the size of intracellular structures changes as cells grow and divide. Indeed, many organelles, such as the nucleus [1, 2], mitochondria [3], mitotic spindle [4, 5], and centrosome [6], exhibit size scaling, a phenomenon in which organelle size depends linearly on cell size. However, the mechanisms of organelle size scaling remain unclear. Here, we show that the size of the nucleolus, a membraneless organelle important for cell-size homeostasis [7], is coupled to cell size by an intracellular phase transition. We find that nucleolar size directly scales with cell size in early C. elegans embryos. Surprisingly, however, when embryo size is altered, we observe inverse scaling: nucleolar size increases in small cells and decreases in large cells. We demonstrate that this seemingly contradictory result arises from maternal loading of a fixed number rather than a fixed concentration of nucleolar components, which condense into nucleoli only above a threshold concentration. Our results suggest that the physics of phase transitions can dictate whether an organelle assembles, and, if so, its size, providing a mechanistic link between organelle assembly and cell size. Since the nucleolus is known to play a key role in cell growth, this biophysical readout of cell size could provide a novel feedback mechanism for growth control. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Human Gait Recognition Based on Multiview Gait Sequences

    Xiaxi Huang

    2008-05-01

    Full Text Available Most of the existing gait recognition methods rely on a single view, usually the side view, of the walking person. This paper investigates the case in which several views are available for gait recognition. It is shown that each view has unequal discrimination power and, therefore, should have unequal contribution in the recognition process. In order to exploit the availability of multiple views, several methods for the combination of the results that are obtained from the individual views are tested and evaluated. A novel approach for the combination of the results from several views is also proposed based on the relative importance of each view. The proposed approach generates superior results, compared to those obtained by using individual views or by using multiple views that are combined using other combination methods.

  2. Driving electromechanically assisted Gait Trainer for people with stroke.

    Iosa, Marco; Morone, Giovanni; Bragoni, Maura; De Angelis, Domenico; Venturiero, Vincenzo; Coiro, Paola; Pratesi, Luca; Paolucci, Stefano

    2011-01-01

    Electromechanically assisted gait training is a promising task-oriented approach for gait restoration, especially for people with subacute stroke. However, few guidelines are available for selecting the parameter values of the electromechanical Gait Trainer (GT) (Reha-Stim; Berlin, Germany) and none is tailored to a patient's motor capacity. We assessed 342 GT sessions performed by 20 people with stroke who were stratified by Functional Ambulatory Category. In the first GT session of all patients, the body-weight support (BWS) required was higher than that reported in the literature. In further sessions, we noted a slow reduction of BWS and a fast increment of walking speed for the most-affected patients. Inverse trends were observed for the less-affected patients. In all the patients, the heart rate increment was about 20 beats per minute, even for sessions in which the number of strides performed was up to 500. In addition, the effective BWS measured during GT sessions was different from that initially selected by the physiotherapist. This difference depended mainly on the position of the GT platforms during selection. Finally, harness acceleration in the anteroposterior direction proved to be higher in patients with stroke than in nondisabled subjects. Our findings are an initial step toward scientifically selecting parameters in electromechanically assisted gait training.

  3. Reentrant behavior in the superconducting phase-dependent resistance of a disordered two-dimensional electron gas

    den Hartog, S.G.; Wees, B.J.van; Klapwijk, T.M; Nazarov, Y.V.; Borghs, G.

    1997-01-01

    We have investigated the bias-voltage dependence of the phase-dependent differential resistance of a disordered T-shaped two-dimensional electron gas coupled to two superconducting terminals. The resistance oscillations first increase upon lowering the energy. For bias voltages below the Thouless

  4. Manganese oxide phases and morphologies: A study on calcination temperature and atmospheric dependence

    Matthias Augustin

    2015-01-01

    Full Text Available Manganese oxides are one of the most important groups of materials in energy storage science. In order to fully leverage their application potential, precise control of their properties such as particle size, surface area and Mnx+ oxidation state is required. Here, Mn3O4 and Mn5O8 nanoparticles as well as mesoporous α-Mn2O3 particles were synthesized by calcination of Mn(II glycolate nanoparticles obtained through an economical route based on a polyol synthesis. The preparation of the different manganese oxides via one route facilitates assigning actual structure–property relationships. The oxidation process related to the different MnOx species was observed by in situ X-ray diffraction (XRD measurements showing time- and temperature-dependent phase transformations occurring during oxidation of the Mn(II glycolate precursor to α-Mn2O3 via Mn3O4 and Mn5O8 in O2 atmosphere. Detailed structural and morphological investigations using transmission electron microscopy (TEM and powder XRD revealed the dependence of the lattice constants and particle sizes of the MnOx species on the calcination temperature and the presence of an oxidizing or neutral atmosphere. Furthermore, to demonstrate the application potential of the synthesized MnOx species, we studied their catalytic activity for the oxygen reduction reaction in aprotic media. Linear sweep voltammetry revealed the best performance for the mesoporous α-Mn2O3 species.

  5. Effects of Dual-Channel Functional Electrical Stimulation on Gait Performance in Patients with Hemiparesis

    Shmuel Springer

    2012-01-01

    Full Text Available The study objective was to assess the effect of functional electrical stimulation (FES applied to the peroneal nerve and thigh muscles on gait performance in subjects with hemiparesis. Participants were 45 subjects (age 57.8 ± 14.8 years with hemiparesis (5.37 ± 5.43 years since diagnosis demonstrating a foot-drop and impaired knee control. Thigh stimulation was applied either to the quadriceps or hamstrings muscles, depending on the dysfunction most affecting gait. Gait was assessed during a two-minute walk test with/without stimulation and with peroneal stimulation alone. A second assessment was conducted after six weeks of daily use. The addition of thigh muscles stimulation to peroneal stimulation significantly enhanced gait velocity measures at the initial and second evaluation. Gait symmetry was enhanced by the dual-channel stimulation only at the initial evaluation, and single-limb stance percentage only at the second assessment. For example, after six weeks, the two-minute gait speed with peroneal stimulation and with the dual channel was 0.66 ± 0.30 m/sec and 0.70 ± 0.31 m/sec, respectively (. In conclusion, dual-channel FES may enhance gait performance in subjects with hemiparesis more than peroneal FES alone.

  6. The Comparison of Falling Risk of Elderly by Speed Gait Test Under Dual Tasks Conditions

    Zahra Fathi Rezaie

    2010-07-01

    Full Text Available Objectives: This study aimed to compare elderly fallers and non fallers by balance test under dual tasks conditions. Methods & Materials: This study was a analyse-comparative study. Subjects were chosen from three parks of Tehran. Subjects were 20 older adults with no history of falls (aged 72.60±5 years and 21 older adults with a history of 2 or more falls in the last one year (aged 74.50±6 Years. All subjects performed speed gait test under 3 conditions (speed gait, speed gait with numbers counter randomly [speed gait cognitive], and speed gait while carrying a full cup of water [speed gait manual]. Data was analysed from multivariate analysis with SPSS 17. Results: The results showed significant difference between elderly fallers and non fallers in fall risk composed dependent variable (P=0.0005, as the non fallers had greater score than elderly fallers. Conclusion: Consequently, we can apply the Gait Speed test under both dual task conditions (Cognitive and Motor for identification of risk of falling in elderly adults with and without of falling history.

  7. The link between weight shift asymmetry and gait disturbances in chronic hemiparetic stroke patients

    Szopa A

    2017-12-01

    Full Text Available Andrzej Szopa,1 Małgorzata Domagalska-Szopa,2 Anetta Lasek-Bal,3 Amadeusz Żak3 1Department of Physiotherapy, 2Department of Medical Rehabilitation, School of Health Sciences in Katowice, 3Department of Neurology, Professor Leszek Giec Upper Silesian Medical Centre, Medical University of Silesia, Katowice, Poland Introduction: While the asymmetry of body posture and the asymmetrical nature of hemiparetic gait in poststroke (PS patients are well documented, the role of weight shift asymmetry in gait disorders after stroke remains unclear. Objective: We examined the association of weight-bearing asymmetry (WBA between paretic and nonparetic lower limbs during quiet standing with the degree of deviation of hemiplegic gait from normal gait evaluated by the Gillette Gait Index (GGI incorporating 16 distinct clinically important kinematic and temporal parameters in chronic PS patients.Participants and methods: Twenty-two ambulatory patients with chronic stroke aged between 50 and 75 years were included in this study. Fourteen patients had hemiparesis on the nondominant side and 8 on the dominant side. The mean time PS was 2 years and 6 months. The reference group consisted of 22 students from the University of the Third Age presenting no neurological disorders. The examination consisted of posturographic weight-bearing (WB distribution and 3-dimensional gait analyses.Results: A significant positive relationship between WBA and GGI was revealed. Moreover, we observed a significant negative association between WBA and paretic step length and walking speed. With regard to kinematic data, the range of motion of knee flexion and peak dorsiflexion in the swing phase of the paretic leg were significantly negatively associated with WBA.Conclusion: Although further research is needed to determine a causal link between postural control asymmetry and gait disturbance in hemiplegics, our findings support the inclusion of WB measurements between paretic and

  8. Effects of real-time gait biofeedback on paretic propulsion and gait biomechanics in individuals post-stroke.

    Genthe, Katlin; Schenck, Christopher; Eicholtz, Steven; Zajac-Cox, Laura; Wolf, Steven; Kesar, Trisha M

    2018-04-01

    Objectives Gait training interventions that target paretic propulsion induce improvements in walking speed and function in individuals post-stroke. Previously, we demonstrated that able-bodied individuals increase propulsion unilaterally when provided real-time biofeedback targeting anterior ground reaction forces (AGRF). The purpose of this study was to, for the first time, investigate short-term effects of real-time AGRF gait biofeedback training on post-stroke gait. Methods Nine individuals with post-stroke hemiparesis (6 females, age = 54 ± 12.4 years 39.2 ± 24.4 months post-stroke) completed three 6-minute training bouts on an instrumented treadmill. During training, visual and auditory biofeedback were provided to increase paretic AGRF during terminal stance. Gait biomechanics were evaluated before training, and during retention tests conducted 2, 15, and 30 minutes post-training. Primary dependent variables were paretic and non-paretic peak AGRF; secondary variables included paretic and non-paretic peak trailing limb angle, plantarflexor moment, and step length. In addition to evaluating the effects of biofeedback training on these dependent variables, we compared effects of a 6-minute biofeedback training bout to a non-biofeedback control condition. Results Compared to pre-training, significantly greater paretic peak AGRFs were generated during the 2, 15, and 30-minute retention tests conducted after the 18-minute biofeedback training session. Biofeedback training induced no significant effects on the non-paretic leg. Comparison of a 6-minute biofeedback training bout with a speed-matched control bout without biofeedback demonstrated a main effect for training type, with greater peak AGRF generation during biofeedback. Discussion Our results suggest that AGRF biofeedback may be a feasible and promising gait training strategy to target propulsive deficits in individuals post-stroke.

  9. Gait training reduces ankle joint stiffness and facilitates heel strike in children with Cerebral Palsy

    Willerslev-Olsen, Maria; Lorentzen, Jakob; Nielsen, Jens Bo

    2014-01-01

    and facilitate heel strike in children with CP? METHODS: Seventeen children with CP (4-14 years) were recruited. Muscle stiffness and gait ability were measured twice before and twice after training with an interval of one month. Passive and reflex-mediated stiffness were measured by a dynamometer which applied...... in stiffness following training (P = 0.01). Toe lift in the swing phase (P = 0.014) and heel impact (P = 0.003) increased significantly following the training during both treadmill and over-ground walking. CONCLUSIONS: Daily intensive gait training may influence the elastic properties of ankle joint muscles...... and facilitate toe lift and heel strike in children with CP. Intensive gait training may be beneficial in preventing contractures and maintain gait ability in children with CP....

  10. Impact of Dual Task on Parkinson's Disease, Stroke and Ataxia Patients' Gait: A Comparative Analysis

    Michelly Arjona Maciel

    2014-01-01

    Full Text Available Introduction: Performing dual task for neurological patients is complex and it can be influenced by the localization of the neurological lesion. Objective: Comparing the impact of dual task on gait in patients with Parkinson's disease, stroke and ataxia. Method: Subjects with Parkinson's disease (PD in initial phase, stroke and ataxia, with independent gait, were evaluated while doing simple gait, with cognitive, motor and cognitive-motor gait demand, assessing average speed and number of steps. Results: Ataxia and stroke patients, compared with PD, showed an increase in the number of steps and decrease the average speed on the march with cognitive demand. Subjects with PD performed better on tasks when compared to others. Conclusion: In this study the impact of dual task was lower in Parkinson's disease patients.

  11. Phase-field modeling of mixing/demixing of regular binary mixtures with a composition-dependent viscosity

    Lamorgese, A.; Mauri, R.

    2017-04-01

    We simulate the mixing (demixing) process of a quiescent binary liquid mixture with a composition-dependent viscosity which is instantaneously brought from the two-phase (one-phase) to the one-phase (two-phase) region of its phase diagram. Our theoretical approach follows a standard diffuse-interface model of partially miscible regular binary mixtures wherein convection and diffusion are coupled via a nonequilibrium capillary force, expressing the tendency of the phase-separating system to minimize its free energy. Based on 2D simulation results, we discuss the influence of viscosity ratio on basic statistics of the mixing (segregation) process triggered by a rapid heating (quench), assuming that the ratio of capillary to viscous forces (a.k.a. the fluidity coefficient) is large. We show that, for a phase-separating system, at a fixed value of the fluidity coefficient (with the continuous phase viscosity taken as a reference), the separation depth and the characteristic length of single-phase microdomains decrease monotonically for increasing values of the viscosity of the dispersed phase. This variation, however, is quite small, in agreement with experimental results. On the other hand, as one might expect, at a fixed viscosity of the dispersed phase both of the above statistics increase monotonically as the viscosity of the continuous phase decreases. Finally, we show that for a mixing system the attainment of a single-phase equilibrium state by coalescence and diffusion is retarded by an increase in the viscosity ratio at a fixed fluidity for the dispersed phase. In fact, for large enough values of the viscosity ratio, a thin film of the continuous phase becomes apparent when two drops of the minority phase approach each other, which further retards coalescence.

  12. Gait Planning Research for an Electrically Driven Large-Load-Ratio Six-Legged Robot

    Hong-Chao Zhuang

    2017-03-01

    Full Text Available Gait planning is an important basis for the walking of a legged robot. To improve the walking stability of multi-legged robots and to reduce the impact force between the foot and the ground, gait planning strategies are presented for an electrically driven large-load-ratio six-legged robot. First, the configuration and walking gait of the electrically driven large-load-ratio six-legged robot are designed. The higher-stable swing sequences of legs and typical walking modes are respectively obtained. Based on the Denavit–Hartenberg (D–H method, the analyses of the forward and inverse kinematics are implemented. The mathematical models of the articulated rotation angles are respectively established. In view of the buffer device installed at the end of shin to decrease the impact force between the foot and the ground, an initial lift height of the leg is brought into gait planning when the support phase changes into the transfer phase. The mathematical models of foot trajectories are established. Finally, a prototype of the electrically driven large-load-ratio six-legged robot is developed. The experiments of the prototype are carried out regarding the aspects of the walking speed and surmounting obstacle. Then, the reasonableness of gait planning is verified based on the experimental results. The proposed strategies of gait planning lay the foundation for effectively reducing the foot–ground impact force and can provide a reference for other large-load-ratio multi-legged robots.

  13. Gait Is Associated with Cognitive Flexibility: A Dual-Tasking Study in Healthy Older People

    Markus A. Hobert

    2017-05-01

    Full Text Available Objectives: To analyze which gait parameters are primarily influenced by cognitive flexibility, and whether such an effect depends on the walking condition used.Design: Cross-sectional analysis.Setting: Tübingen evaluation of Risk factors for Early detection of Neurodegenerative Disorders.Participants: A total of 661 non-demented individuals (49–80 years.Measurements: A gait assessment with four conditions was performed: a 20 m walk at convenient speed (C, at fast speed (F, at fast speed while checking boxes (FB, and while subtracting serial 7s (FS. Seven gait parameters from a wearable sensor-unit (McRoberts, Netherlands were compared with delta Trail-Making-Test (dTMT values, which is a measure of cognitive flexibility. Walking strategies of good and poor dTMT performers were compared by evaluating the patterns of gait parameters across conditions.Results: Five parameters correlated significantly with the dTMT in the FS condition, two parameters in the F and FB condition, and none in the C condition. Overall correlations were relatively weak. Gait speed was the gait parameter that most strongly correlated with the dTMT (r2 = 7.4%. In good, but not poor, dTMT performers differences between FB and FS were significantly different in variability-associated gait parameters.Conclusion: Older individuals need cognitive flexibility to perform difficult walking conditions. This association is best seen in gait speed. New and particularly relevant for recognition and training of deficits is that older individuals with poor cognitive flexibility have obviously fewer resources to adapt to challenging walking conditions. Our findings partially explain gait deficits in older adults with poor cognitive flexibility.

  14. Gait, posture and cognition in Parkinson's disease

    Barbosa, Alessandra Ferreira; Chen, Janini; Freitag, Fernanda; Valente, Debora; Souza, Carolina de Oliveira; Voos, Mariana Callil; Chien, Hsin Fen

    2016-01-01

    ABSTRACT Gait disorders and postural instability are the leading causes of falls and disability in Parkinson's disease (PD). Cognition plays an important role in postural control and may interfere with gait and posture assessment and treatment. It is important to recognize gait, posture and balance dysfunctions by choosing proper assessment tools for PD. Patients at higher risk of falling must be referred for rehabilitation as early as possible, because antiparkinsonian drugs and surgery do n...

  15. Performance analysis for gait in camera networks

    Michela Goffredo; Imed Bouchrika; John Carter; Mark Nixon

    2008-01-01

    This paper deploys gait analysis for subject identification in multi-camera surveillance scenarios. We present a new method for viewpoint independent markerless gait analysis that does not require camera calibration and works with a wide range of directions of walking. These properties make the proposed method particularly suitable for gait identification in real surveillance scenarios where people and their behaviour need to be tracked across a set of cameras. Tests on 300 synthetic and real...

  16. Inter-Trial Gait Variability Reduction Using Continous Curve Registration

    Sadeghi, H

    2001-01-01

    Timing in peak gait values shifts slightly between gait trials. When gait data are averaged, some of the standard deviation can be associated to this inter-trial variability unless normalization is carried out beforehand...

  17. Invariance of the Berry phase under unitary transformations: application to the time-dependent generalized harmonic oscillator

    Kobe, D.H.

    1989-01-01

    The Berry phase is derived in a manifestly gauge-invariant way, without adiabatic or cyclic requirements. It is invariant under unitary transformations, contrary to recent assertions. A time-dependent generalized harmonic oscillator is taken as an example. The energy of the system is not in general the Hamiltonian. An energy, the time derivative of which is the power, is obtained from the equation of motion. When the system is quantized, the Berry phase is zero, and is invariant under unitary transformations. If the energy is chosen incorrectly to be the Hamiltonian, a nonzero Berry phase is obtained. In this case the total phase, the sun of the dynamical and Berry phases, is equal to the correct total phase through first order in perturbation theory. (author)

  18. Gait-related cerebral alterations in patients with Parkinson's disease with freezing of gait

    Snijders, A.H.; Leunissen, H.P.; Bakker, M.; Overeem, S.; Helmich, R.C.G.; Bloem, B.R.; Toni, I.

    2011-01-01

    Freezing of gait is a common, debilitating feature of Parkinson’s disease. We have studied gait planning in patients with freezing of gait, using motor imagery of walking in combination with functional magnetic resonance imaging. This approach exploits the large neural overlap that exists between

  19. Gait-related cerebral alterations in patients with Parkinson's disease with freezing of gait

    Snijders, A.H.; Leunissen, I.; Bakker, M.; Overeem, S.; Helmich, R.C.G.; Bloem, B.R.; Toni, I.

    2011-01-01

    Freezing of gait is a common, debilitating feature of Parkinson's disease. We have studied gait planning in patients with freezing of gait, using motor imagery of walking in combination with functional magnetic resonance imaging. This approach exploits the large neural overlap that exists between

  20. Early presentation of gait impairment in Wolfram Syndrome

    Pickett Kristen A

    2012-12-01

    Full Text Available Abstract Background Classically characterized by early onset insulin-dependent diabetes mellitus, optic atrophy, deafness, diabetes insipidus, and neurological abnormalities, Wolfram syndrome (WFS is also associated with atypical brainstem and cerebellar findings in the first decade of life. As such, we hypothesized that gait differences between individuals with WFS and typically developing (TD individuals may be detectable across the course of the disease. Methods Gait was assessed for 13 individuals with WFS (min 6.4 yrs, max 25.8 yrs and 29 age-matched, typically developing individuals (min 5.6 yrs, max 28.5 yrs using a GAITRite ® walkway system. Velocity, cadence, step length, base of support and double support time were compared between groups. Results Across all tasks, individuals with WFS walked slower (p = 0.03, took shorter (p ≤ 0.001 and wider (p ≤ 0.001 steps and spent a greater proportion of the gait cycle in double support (p = 0.03 compared to TD individuals. Cadence did not differ between groups (p = 0.62. Across all tasks, age was significantly correlated with cadence and double support time in the TD group but only double support time was correlated with age in the WFS group and only during preferred pace forward (rs= 0.564, p = 0.045 and dual task forward walking (rs= 0.720, p = 0.006 tasks. Individuals with WFS also had a greater number of missteps during tandem walking (p ≤ 0.001. Within the WFS group, spatiotemporal measures of gait did not correlate with measures of visual acuity. Balance measures negatively correlated with normalized gait velocity during fast forward walking (rs = −0.59, p = 0.03 and percent of gait cycle in double support during backward walking (rs = −0.64, p = 0.03. Conclusions Quantifiable gait impairments can be detected in individuals with WFS earlier than previous clinical observations suggested. These impairments are not fully accounted for by the visual or balance deficits

  1. Early presentation of gait impairment in Wolfram Syndrome.

    Pickett, Kristen A; Duncan, Ryan P; Hoekel, James; Marshall, Bess; Hershey, Tamara; Earhart, Gammon M

    2012-12-08

    Classically characterized by early onset insulin-dependent diabetes mellitus, optic atrophy, deafness, diabetes insipidus, and neurological abnormalities, Wolfram syndrome (WFS) is also associated with atypical brainstem and cerebellar findings in the first decade of life. As such, we hypothesized that gait differences between individuals with WFS and typically developing (TD) individuals may be detectable across the course of the disease. Gait was assessed for 13 individuals with WFS (min 6.4 yrs, max 25.8 yrs) and 29 age-matched, typically developing individuals (min 5.6 yrs, max 28.5 yrs) using a GAITRite ® walkway system. Velocity, cadence, step length, base of support and double support time were compared between groups. Across all tasks, individuals with WFS walked slower (p = 0.03), took shorter (p ≤ 0.001) and wider (p ≤ 0.001) steps and spent a greater proportion of the gait cycle in double support (p = 0.03) compared to TD individuals. Cadence did not differ between groups (p = 0.62). Across all tasks, age was significantly correlated with cadence and double support time in the TD group but only double support time was correlated with age in the WFS group and only during preferred pace forward (rs = 0.564, p = 0.045) and dual task forward walking (rs = 0.720, p = 0.006) tasks. Individuals with WFS also had a greater number of missteps during tandem walking (p ≤ 0.001). Within the WFS group, spatiotemporal measures of gait did not correlate with measures of visual acuity. Balance measures negatively correlated with normalized gait velocity during fast forward walking (rs = -0.59, p = 0.03) and percent of gait cycle in double support during backward walking (rs = -0.64, p = 0.03). Quantifiable gait impairments can be detected in individuals with WFS earlier than previous clinical observations suggested. These impairments are not fully accounted for by the visual or balance deficits associated with WFS, and may be a reflection of early cerebellar and

  2. Dependence of charge transfer phenomena during solid-air two-phase flow on particle disperser

    Tanoue, Ken-ichiro; Suedomi, Yuuki; Honda, Hirotaka; Furutani, Satoshi; Nishimura, Tatsuo; Masuda, Hiroaki

    2012-12-01

    An experimental investigation of the tribo-electrification of particles has been conducted during solid-air two-phase turbulent flow. The current induced in a metal plate by the impact of polymethylmethacrylate (PMMA) particles in a high-speed air flow was measured for two different plate materials. The results indicated that the contact potential difference between the particles and a stainless steel plate was positive, while for a nickel plate it was negative. These results agreed with theoretical contact charge transfer even if not only the particle size but also the kind of metal plate was changed. The specific charge of the PMMA particles during solid-air two-phase flow using an ejector, a stainless steel branch pipe, and a stainless steel straight pipe was measured using a Faraday cage. Although the charge was negative in the ejector, the particles had a positive specific charge at the outlet of the branch pipe, and this positive charge increased in the straight pipe. The charge decay along the flow direction could be reproduced by the charging and relaxation theory. However, the proportional coefficients in the theory changed with the particle size and air velocity. Therefore, an unexpected charge transfer occurred between the ejector and the branch pipe, which could not be explained solely by the contact potential difference. In the ejector, an electrical current in air might have been produced by self-discharge of particles with excess charge between the nickel diffuser in the ejector and the stainless steel nozzle or the stainless steel pipe due to a reversal in the contact potential difference between the PMMA and the stainless steel. The sign of the current depended on the particle size, possibly because the position where the particles impacted depended on their size. When dual coaxial glass pipes were used as a particle disperser, the specific charge of the PMMA particles became more positive along the particle flow direction due to the contact

  3. A fourth gradient to overcome slice dependent phase effects of voxel-sized coils in planar arrays.

    Bosshard, John C; Eigenbrodt, Edwin P; McDougall, Mary P; Wright, Steven M

    2010-01-01

    The signals from an array of densely spaced long and narrow receive coils for MRI are complicated when the voxel size is of comparable dimension to the coil size. The RF coil causes a phase gradient across each voxel, which is dependent on the distance from the coil, resulting in a slice dependent shift of k-space. A fourth gradient coil has been implemented and used with the system's gradient set to create a gradient field which varies with slice. The gradients are pulsed together to impart a slice dependent phase gradient to compensate for the slice dependent phase due to the RF coils. However the non-linearity in the fourth gradient which creates the desired slice dependency also results in a through-slice phase ramp, which disturbs normal slice refocusing and leads to additional signal cancelation and reduced field of view. This paper discusses the benefits and limitations of using a fourth gradient coil to compensate for the phase due to RF coils.

  4. Gait recognition based on integral outline

    Ming, Guan; Fang, Lv

    2017-02-01

    Biometric identification technology replaces traditional security technology, which has become a trend, and gait recognition also has become a hot spot of research because its feature is difficult to imitate and theft. This paper presents a gait recognition system based on integral outline of human body. The system has three important aspects: the preprocessing of gait image, feature extraction and classification. Finally, using a method of polling to evaluate the performance of the system, and summarizing the problems existing in the gait recognition and the direction of development in the future.

  5. Gait, posture and cognition in Parkinson's disease

    Alessandra Ferreira Barbosa

    Full Text Available ABSTRACT Gait disorders and postural instability are the leading causes of falls and disability in Parkinson's disease (PD. Cognition plays an important role in postural control and may interfere with gait and posture assessment and treatment. It is important to recognize gait, posture and balance dysfunctions by choosing proper assessment tools for PD. Patients at higher risk of falling must be referred for rehabilitation as early as possible, because antiparkinsonian drugs and surgery do not improve gait and posture in PD.

  6. Inhibition of autophagy enhances DNA damage-induced apoptosis by disrupting CHK1-dependent S phase arrest

    Liou, Jong-Shian; Wu, Yi-Chen; Yen, Wen-Yen; Tang, Yu-Shuan [Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan, ROC (China); Kakadiya, Rajesh B.; Su, Tsann-Long [Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan, ROC (China); Yih, Ling-Huei, E-mail: lhyih@gate.sinica.edu.tw [Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan, ROC (China)

    2014-08-01

    DNA damage has been shown to induce autophagy, but the role of autophagy in the DNA damage response and cell fate is not fully understood. BO-1012, a bifunctional alkylating derivative of 3a-aza-cyclopenta[a]indene, is a potent DNA interstrand cross-linking agent with anticancer activity. In this study, BO-1012 was found to reduce DNA synthesis, inhibit S phase progression, and induce phosphorylation of histone H2AX on serine 139 (γH2AX) exclusively in S phase cells. Both CHK1 and CHK2 were phosphorylated in response to BO-1012 treatment, but only depletion of CHK1, but not CHK2, impaired BO-1012-induced S phase arrest and facilitated the entry of γH2AX-positive cells into G2 phase. CHK1 depletion also significantly enhanced BO-1012-induced cell death and apoptosis. These results indicate that BO-1012-induced S phase arrest is a CHK1-dependent pro-survival response. BO-1012 also resulted in marked induction of acidic vesicular organelle (AVO) formation and microtubule-associated protein 1 light chain 3 (LC3) processing and redistribution, features characteristic of autophagy. Depletion of ATG7 or co-treatment of cells with BO-1012 and either 3-methyladenine or bafilomycin A1, two inhibitors of autophagy, not only reduced CHK1 phosphorylation and disrupted S phase arrest, but also increased cleavage of caspase-9 and PARP, and cell death. These results suggest that cells initiate S phase arrest and autophagy as pro-survival responses to BO-1012-induced DNA damage, and that suppression of autophagy enhances BO-1012-induced apoptosis via disruption of CHK1-dependent S phase arrest. - Highlights: • Autophagy inhibitors enhanced the cytotoxicity of a DNA alkylating agent, BO-1012. • BO-1012-induced S phase arrest was a CHK1-dependent pro-survival response. • Autophagy inhibition enhanced BO-1012 cytotoxicity via disrupting the S phase arrest.

  7. Effects of the addition of functional electrical stimulation to ground level gait training with body weight support after chronic stroke.

    Prado-Medeiros, Christiane L; Sousa, Catarina O; Souza, Andréa S; Soares, Márcio R; Barela, Ana M F; Salvini, Tania F

    2011-01-01

    The addition of functional electrical stimulation (FES) to treadmill gait training with partial body weight support (BWS) has been proposed as a strategy to facilitate gait training in people with hemiparesis. However, there is a lack of studies that evaluate the effectiveness of FES addition on ground level gait training with BWS, which is the most common locomotion surface. To investigate the additional effects of commum peroneal nerve FES combined with gait training and BWS on ground level, on spatial-temporal gait parameters, segmental angles, and motor function. Twelve people with chronic hemiparesis participated in the study. An A1-B-A2 design was applied. A1 and A2 corresponded to ground level gait training using BWS, and B corresponded to the same training with the addition of FES. The assessments were performed using the Modified Ashworth Scale (MAS), Functional Ambulation Category (FAC), Rivermead Motor Assessment (RMA), and filming. The kinematics analyzed variables were mean walking speed of locomotion; step length; stride length, speed and duration; initial and final double support duration; single-limb support duration; swing period; range of motion (ROM), maximum and minimum angles of foot, leg, thigh, and trunk segments. There were not changes between phases for the functional assessment of RMA, for the spatial-temporal gait variables and segmental angles, no changes were observed after the addition of FES. The use of FES on ground level gait training with BWS did not provide additional benefits for all assessed parameters.

  8. Spatiotemporal organization of alpha-motoneuron activity in the human spinal cord during different gaits and gait transitions.

    Ivanenko, Y P; Cappellini, G; Poppele, R E; Lacquaniti, F

    2008-06-01

    Here we studied the spatiotemporal organization of motoneuron (MN) activity during different human gaits. We recorded the electromyographic (EMG) activity patterns in 32 ipsilateral limb and trunk muscles from normal subjects while running and walking on a treadmill (3-12 km/h). In addition, we recorded backward walking and skipping, a distinct human gait that comprises the features of both walking and running. We mapped the recorded EMG activity patterns onto the spinal cord in approximate rostrocaudal locations of the MN pools. The activation of MNs tends to occur in bursts and be segregated by spinal segment in a gait-specific manner. In particular, sacral and cervical activation timings were clearly gait-dependent. Swing-related activity constituted an appreciable fraction (> 30%) of the total MN activity of leg muscles. Locomoting at non-preferred speeds (running and walking at 5 and 9 km/h, respectively) showed clear differences relative to preferred speeds. Running at low speeds was characterized by wider sacral activation. Walking at high non-preferred speeds was accompanied by an 'atypical' locus of activation in the upper lumbar spinal cord during late stance and by a drastically increased activation of lumbosacral segments. The latter findings suggest that the optimal speed of gait transitions may be related to an optimal intensity of the total MN activity, in addition to other factors previously described. The results overall support the idea of flexibility and adaptability of spatiotemporal activity in the spinal circuitry with constraints on the temporal functional connectivity of hypothetical pulsatile burst generators.

  9. Reference Determinant Dependence of the Random Phase Approximation in 3d Transition Metal Chemistry.

    Bates, J E; Mezei, P D; Csonka, G I; Sun, J; Ruzsinszky, A

    2017-01-10

    Without extensive fitting, accurate prediction of transition metal chemistry is a challenge for semilocal and hybrid density funcitonals. The Random Phase Approximation (RPA) has been shown to yield superior results to semilocal functionals for main group thermochemistry, but much less is known about its performance for transition metals. We have therefore analyzed the behavior of reaction energies, barrier heights, and ligand dissociation energies obtained with RPA and compare our results to several semilocal and hybrid functionals. Particular attention is paid to the reference determinant dependence of RPA. We find that typically the results do not vary much between semilocal or hybrid functionals as a reference, as long as the fraction of exact exchange (EXX) mixing in the hybrid functional is small. For large fractions of EXX mixing, however, the Hartree-Fock-like nature of the determinant can severely degrade the performance. Overall, RPA systematically reduces the errors of semilocal functionals and delivers excellent performance from a single reference determinant for inherently multireference reactions. The behavior of dual hybrids that combine RPA correlation with a hybrid exchange energy was also explored, but ultimately did not lead to a systematic improvement compared to traditional RPA for these systems. We rationalize this conclusion by decomposing the contributions to the reaction energies, and briefly discuss the possible implications for double-hybrid functionals based on RPA. The correlation between EXX mixing and spin-symmetry breaking is also discussed.

  10. Age dependence of spleen- and muscle-corrected hepatic signal enhancement on hepatobiliary phase gadoxetate MRI

    Matoori, Simon [Paracelsus Medical University Salzburg, Department of Radiology, Salzburg (Austria); Hirslanden Clinic St. Anna, Clinical Research Group, Lucerne (Switzerland); Froehlich, Johannes M. [Hirslanden Clinic St. Anna, Clinical Research Group, Lucerne (Switzerland); ETH Zurich, Department of Chemistry and Applied Biosciences, Institute of Pharmaceutical Sciences, Zurich (Switzerland); Cantonal Hospital Winterthur, Department of Radiology, Winterthur (Switzerland); Breitenstein, Stefan [Cantonal Hospital Winterthur, Department of Surgery, Clinic for Visceral and Thoracic Surgery, Winterthur (Switzerland); Doert, Aleksis [Cantonal Hospital Winterthur, Department of Radiology, Winterthur (Switzerland); Pozdniakova, Viktoria [Stavanger University Hospital, Department of Radiology, Stavanger (Norway); Koh, Dow-Mu [Royal Marsden Hospital, Department of Radiology, Surrey, England (United Kingdom); Gutzeit, Andreas [Paracelsus Medical University Salzburg, Department of Radiology, Salzburg (Austria); Hirslanden Clinic St. Anna, Clinical Research Group, Lucerne (Switzerland); Cantonal Hospital Winterthur, Department of Radiology, Winterthur (Switzerland)

    2016-06-15

    To identify correlations of signal enhancements (SE) and SE normalized to reference tissues of the spleen, kidney, liver, musculus erector spinae (MES) and ductus hepatocholedochus (DHC) on hepatobiliary phase gadoxetate-enhanced MRI with patient age in non-cirrhotic patients. A heterogeneous cohort of 131 patients with different clinical backgrounds underwent a standardized 3.0-T gadoxetate-enhanced liver MRI between November 2008 and June 2013. After exclusion of cirrhotic patients, a cohort of 75 patients with no diagnosed diffuse liver disease was selected. The ratio of signal intensity 20 min post- to pre-contrast administration (SE) in the spleen, kidney, liver, MES and DHC, and the SE of the kidney, liver and DHC normalized to the reference tissues spleen or MES were compared to patient age. Patient age was inversely correlated with the liver SE normalized to the spleen and MES SE (both p < 0.001) and proportionally with the SE of the spleen (p = 0.043), the MES (p = 0.030) and the kidney (p = 0.022). No significant correlations were observed for the DHC (p = 0.347) and liver SE (p = 0.606). The age dependence of hepatic SE normalized to the enhancement in the spleen and MES calls for a cautious interpretation of these quantification methods. (orig.)

  11. The time-dependent relativistic mean-field theory and the random phase approximation

    Ring, P.; Ma, Zhong-yu; Van Giai, Nguyen; Vretenar, D.; Wandelt, A.; Cao, Li-gang

    2001-01-01

    The Relativistic Random Phase Approximation (RRPA) is derived from the Time-Dependent Relativistic Mean-Field (TD RMF) theory in the limit of small amplitude oscillations. In the no-sea approximation of the RMF theory, the RRPA configuration space includes not only the usual particle-hole ph-states, but also αh-configurations, i.e. pairs formed from occupied states in the Fermi sea and empty negative-energy states in the Dirac sea. The contribution of the negative-energy states to the RRPA matrices is examined in a schematic model, and the large effect of Dirac-sea states on isoscalar strength distributions is illustrated for the giant monopole resonance in 116 Sn. It is shown that, because the matrix elements of the time-like component of the vector-meson fields which couple the αh-configurations with the ph-configurations are strongly reduced with respect to the corresponding matrix elements of the isoscalar scalar meson field, the inclusion of states with unperturbed energies more than 1.2 GeV below the Fermi energy has a pronounced effect on giant resonances with excitation energies in the MeV region. The influence of nuclear magnetism, i.e. the effect of the spatial components of the vector fields is examined, and the difference between the nonrelativistic and relativistic RPA predictions for the nuclear matter compression modulus is explained

  12. Distance-dependent metal enhanced fluorescence by flowerlike silver nanostructures fabricated in liquid crystalline phase

    Zhang, Ying; Yang, Chengliang; Zhang, Guiyang; Peng, Zenghui; Yao, Lishuang; Wang, Qidong; Cao, Zhaoliang; Mu, Quanquan; Xuan, Li

    2017-10-01

    Flowerlike silver nanostructure substrates were fabricated in liquid crystalline phase and the distance dependent property of metal enhanced fluorescence for such substrate was studied for the first time. The distance between silver nanostructures and fluorophore was controlled by the well-established layer-by-layer (LbL) technique constructing alternate layers of poly (allylamine hydrochloride) (PAH) and poly (sodium 4-styrenesulfonate) (PSS). The Rhodamine 6G (R6G) molecules were electrostatically attached to the outmost negative charged PSS layer. The fluorescence enhancement factor of flowerlike nanostructure substrate increased firstly and then decreased with the distance increasing. The best enhanced fluorescence intensity of 71 fold was obtained at a distance of 5.2 nm from the surface of flowerlike silver nanostructure. The distance for best enhancement effect is an instructive parameter for the applications of such substrates and could be used in the practical MEF applications with the flowerlike nanostructure substrates fabricated in such way which is simple, controllable and cost-effective.

  13. Age dependence of spleen- and muscle-corrected hepatic signal enhancement on hepatobiliary phase gadoxetate MRI

    Matoori, Simon; Froehlich, Johannes M.; Breitenstein, Stefan; Doert, Aleksis; Pozdniakova, Viktoria; Koh, Dow-Mu; Gutzeit, Andreas

    2016-01-01

    To identify correlations of signal enhancements (SE) and SE normalized to reference tissues of the spleen, kidney, liver, musculus erector spinae (MES) and ductus hepatocholedochus (DHC) on hepatobiliary phase gadoxetate-enhanced MRI with patient age in non-cirrhotic patients. A heterogeneous cohort of 131 patients with different clinical backgrounds underwent a standardized 3.0-T gadoxetate-enhanced liver MRI between November 2008 and June 2013. After exclusion of cirrhotic patients, a cohort of 75 patients with no diagnosed diffuse liver disease was selected. The ratio of signal intensity 20 min post- to pre-contrast administration (SE) in the spleen, kidney, liver, MES and DHC, and the SE of the kidney, liver and DHC normalized to the reference tissues spleen or MES were compared to patient age. Patient age was inversely correlated with the liver SE normalized to the spleen and MES SE (both p < 0.001) and proportionally with the SE of the spleen (p = 0.043), the MES (p = 0.030) and the kidney (p = 0.022). No significant correlations were observed for the DHC (p = 0.347) and liver SE (p = 0.606). The age dependence of hepatic SE normalized to the enhancement in the spleen and MES calls for a cautious interpretation of these quantification methods. (orig.)

  14. Phase separation driven by density-dependent movement: A novel mechanism for ecological patterns.

    Liu, Quan-Xing; Rietkerk, Max; Herman, Peter M J; Piersma, Theunis; Fryxell, John M; van de Koppel, Johan

    2016-12-01

    Many ecosystems develop strikingly regular spatial patterns because of small-scale interactions between organisms, a process generally referred to as spatial self-organization. Self-organized spatial patterns are important determinants of the functioning of ecosystems, promoting the growth and survival of the involved organisms, and affecting the capacity of the organisms to cope with changing environmental conditions. The predominant explanation for self-organized pattern formation is spatial heterogeneity in establishment, growth and mortality, resulting from the self-organization processes. A number of recent studies, however, have revealed that movement of organisms can be an important driving process creating extensive spatial patterning in many ecosystems. Here, we review studies that detail movement-based pattern formation in contrasting ecological settings. Our review highlights that a common principle, where movement of organisms is density-dependent, explains observed spatial regular patterns in all of these studies. This principle, well known to physics as the Cahn-Hilliard principle of phase separation, has so-far remained unrecognized as a general mechanism for self-organized complexity in ecology. Using the examples presented in this paper, we explain how this movement principle can be discerned in ecological settings, and clarify how to test this mechanism experimentally. Our study highlights that animal movement, both in isolation and in unison with other processes, is an important mechanism for regular pattern formation in ecosystems. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Interactions between the phase stress and the grain-orientation-dependent stress in duplex stainless steel during deformation

    Jia, N.; Peng, R. Lin; Wang, Y.D.; Chai, G.C.; Johansson, S.; Wang, G.; Liaw, P.K.

    2006-01-01

    The development of phase stress and grain-orientation-dependent stress under uniaxial compression was investigated in a duplex stainless steel consisting of austenite and ferrite. Using in situ neutron diffraction measurements, the strain response of several h k l planes to the applied compressive stress was mapped as a function of applied stress and sample direction. Analysis based on the experimental results and elastoplastic self-consistent simulations shows that phase stresses of thermal origin further increase during elastic loading but decrease with increased plastic deformation. Grain-orientation-dependent stresses become significant in both austenite and ferrite after loading into the plastic region. After unloading from the plastic regime, a considerable intergranular stress remains in the austenitic phase and dominates over the phase stress. This study provides fundamental experimental inputs for future micromechanical modeling aiming at the evaluation and prediction of the mechanical performance of multiphase materials

  16. Solvent annealing induced phase separation and dewetting in PMMA∕SAN blend film: film thickness and solvent dependence.

    You, Jichun; Zhang, Shuangshuang; Huang, Gang; Shi, Tongfei; Li, Yongjin

    2013-06-28

    The competition between "dewetting" and "phase separation" behaviors in polymer blend films attracts significant attention in the last decade. The simultaneous phase separation and dewetting in PMMA∕SAN [poly(methyl methacrylate) and poly(styrene-ran-acrylonitrile)] blend ultrathin films upon solvent annealing have been observed for the first time in our previous work. In this work, film thickness and annealing solvent dependence of phase behaviors in this system has been investigated using atomic force microscopy and grazing incidence small-angle X-ray scattering (GISAXS). On one hand, both vertical phase separation and dewetting take place upon selective solvent vapor annealing, leading to the formation of droplet∕mimic-film structures with various sizes (depending on original film thickness). On the other hand, the whole blend film dewets the substrate and produces dispersed droplets on the silicon oxide upon common solvent annealing. GISAXS results demonstrate the phase separation in the big dewetted droplets resulted from the thicker film (39.8 nm). In contrast, no period structure is detected in small droplets from the thinner film (5.1 nm and 9.7 nm). This investigation indicates that dewetting and phase separation in PMMA∕SAN blend film upon solvent annealing depend crucially on the film thickness and the atmosphere during annealing.

  17. Blindfolded Balance Training in Patients with Parkinson’s Disease: A Sensory-Motor Strategy to Improve the Gait

    M. Tramontano

    2016-01-01

    Full Text Available Aim. Recent evidence suggested that the use of treadmill training may improve gait parameters. Visual deprivation could engage alternative sensory strategies to control dynamic equilibrium and stabilize gait based on vestibulospinal reflexes (VSR. We aimed to investigate the efficacy of a blindfolded balance training (BBT in the improvement of stride phase percentage reliable gait parameters in patients with Parkinson’s Disease (PD compared to patients treated with standard physical therapy (PT. Methods. Thirty PD patients were randomized in two groups of 15 patients, one group treated with BBT during two weeks and another group treated with standard PT during eight weeks. We evaluated gait parameters before and after BBT and PT interventions, in terms of double stance, swing, and stance phase percentage. Results. BBT induced an improvement of double stance phase as revealed (decreased percentage of double stance phase during the gait cycle in comparison to PT. The other gait parameters swing and stance phase did not differ between the two groups. Discussion. These results support the introduction of complementary rehabilitative strategies based on sensory-motor stimulation in the traditional PD patient’s rehabilitation. Further studies are needed to investigate the neurophysiological circuits and mechanism underlying clinical and motor modifications.

  18. Harmony as a convergence attractor that minimizes the energy expenditure and variability in physiological gait and the loss of harmony in cerebellar ataxia.

    Serrao, Mariano; Chini, Giorgia; Iosa, Marco; Casali, Carlo; Morone, Giovanni; Conte, Carmela; Bini, Fabiano; Marinozzi, Franco; Coppola, Gianluca; Pierelli, Francesco; Draicchio, Francesco; Ranavolo, Alberto

    2017-10-01

    The harmony of the human gait was recently found to be related to the golden ratio value (ϕ). The ratio between the duration of the stance and that of the swing phases of a gait cycle was in fact found to be close to ϕ, which implies that, because of the fractal property of autosimilarity of that number, the gait ratios stride/stance, stance/swing, swing/double support, were not significantly different from one another. We studied a group of patients with cerebellar ataxia to investigate how the differences between their gait ratios and the golden ratio are related to efficiency and stability of their gait, assessed by energy expenditure and stride-to-stride variability, respectively. The gait of 28 patients who were affected by degenerative cerebellar ataxia and of 28 healthy controls was studied using a stereophotogrammetric system. The above mentioned gait ratios, the energy expenditure estimated using the pelvis reconstructed method and the gait variability in terms of the stride length were computed, and their relationships were analyzed. Matching procedures have also been used to avoid multicollinearity biases. The gait ratio values of the patients were farther from the controls (and hence from ϕ), even in speed matched conditions (P=0.011, Cohen's D=0.76), but not when the variability and energy expenditure were matched between the two groups (Cohen's D=0.49). In patients with cerebellar ataxia, the farther the stance-swing ratio was from ϕ, the larger the total mechanical work (R 2 adj =0.64). Further, a significant positive correlation was observed between the difference of the gait ratio from the golden ratio and the severity of the disease (R=0.421, P=0.026). Harmony of gait appears to be a benchmark of physiological gait leading to physiological energy recovery and gait reliability. Neurorehabilitation of patients with ataxia might benefit from the restoration of harmony of their locomotor patterns. Copyright © 2017. Published by Elsevier Ltd.

  19. Effects of Density-Dependent Quark Mass on Phase Diagram of Color-Flavor-Locked Quark Matter

    2006-01-01

    Considering the density dependence of quark mass, we investigate the phase transition between the (unpaired) strange quark matter and the color-flavor-locked matter, which are supposed to be two candidates for the ground state of strongly interacting matter. We find that if the current mass of strange quark ms is small, the strange quark matter remains stable unless the baryon density is very high. If ms is large, the phase transition from the strange quark matter to the color-flavor-locked matter in particular to its gapless phase is found to be different from the results predicted by previous works. A complicated phase diagram of three-flavor quark matter is presented, in which the color-flavor-locked phase region is suppressed for moderate densities.

  20. Asymmetric simple exclusion process with position-dependent hopping rates: Phase diagram from boundary-layer analysis.

    Mukherji, Sutapa

    2018-03-01

    In this paper, we study a one-dimensional totally asymmetric simple exclusion process with position-dependent hopping rates. Under open boundary conditions, this system exhibits boundary-induced phase transitions in the steady state. Similarly to totally asymmetric simple exclusion processes with uniform hopping, the phase diagram consists of low-density, high-density, and maximal-current phases. In various phases, the shape of the average particle density profile across the lattice including its boundary-layer parts changes significantly. Using the tools of boundary-layer analysis, we obtain explicit solutions for the density profile in different phases. A detailed analysis of these solutions under different boundary conditions helps us obtain the equations for various phase boundaries. Next, we show how the shape of the entire density profile including the location of the boundary layers can be predicted from the fixed points of the differential equation describing the boundary layers. We discuss this in detail through several examples of density profiles in various phases. The maximal-current phase appears to be an especially interesting phase where the boundary layer flows to a bifurcation point on the fixed-point diagram.

  1. Comparing electro- and mechano-myographic muscle activation patterns in self-paced pediatric gait.

    Plewa, Katherine; Samadani, Ali; Chau, Tom

    2017-10-01

    Electromyography (EMG) is the standard modality for measuring muscle activity. However, the convenience and availability of low-cost accelerometer-based wearables makes mechanomyography (MMG) an increasingly attractive alternative modality for clinical applications. Literature to date has demonstrated a strong association between EMG and MMG temporal alignment in isometric and isokinetic contractions. However, the EMG-MMG relationship has not been studied in gait. In this study, the concurrence of EMG- and MMG-detected contractions in the tibialis anterior, lateral gastrocnemius, vastus lateralis, and biceps femoris muscles were investigated in children during self-paced gait. Furthermore, the distribution of signal power over the gait cycle was statistically compared between EMG-MMG modalities. With EMG as the reference, muscular contractions were detected based on MMG with balanced accuracies between 88 and 94% for all muscles except the gastrocnemius. MMG signal power differed from that of EMG during certain phases of the gait cycle in all muscles except the biceps femoris. These timing and power distribution differences between the two modalities may in part be related to muscle fascicle length changes that are unique to muscle motion during gait. Our findings suggest that the relationship between EMG and MMG appears to be more complex during gait than in isometric and isokinetic contractions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Synthesis of walking sounds for alleviating gait disturbances in Parkinson's disease.

    Rodger, Matthew W M; Young, William R; Craig, Cathy M

    2014-05-01

    Managing gait disturbances in people with Parkinson's disease is a pressing challenge, as symptoms can contribute to injury and morbidity through an increased risk of falls. While drug-based interventions have limited efficacy in alleviating gait impairments, certain nonpharmacological methods, such as cueing, can also induce transient improvements to gait. The approach adopted here is to use computationally-generated sounds to help guide and improve walking actions. The first method described uses recordings of force data taken from the steps of a healthy adult which in turn were used to synthesize realistic gravel-footstep sounds that represented different spatio-temporal parameters of gait, such as step duration and step length. The second method described involves a novel method of sonifying, in real time, the swing phase of gait using real-time motion-capture data to control a sound synthesis engine. Both approaches explore how simple but rich auditory representations of action based events can be used by people with Parkinson's to guide and improve the quality of their walking, reducing the risk of falls and injury. Studies with Parkinson's disease patients are reported which show positive results for both techniques in reducing step length variability. Potential future directions for how these sound approaches can be used to manage gait disturbances in Parkinson's are also discussed.

  3. Direct Radiofrequency Application Improves Pain and Gait in Collagenase-Induced Acute Achilles Tendon Injury

    Yun-Pu Tsai

    2013-01-01

    Full Text Available Radiofrequency (RF is often used as a supplementary and alternative method to alleviate pain for chronic tendinopathy. Whether or how it would work for acute tendon injury is not addressed in the literatures. Through detailed pain and gait monitoring, we hypothesized that collagenase-induce acute tendinopathy model may be able to answer these questions. Gait parameters, including time, distance, and range of motion, were recorded and analyzed using a walking track equipped with a video-based system. Expression of substance P (SP, calcitonin gene related peptide (CGRP, and galanin were used as pain markers. Beta-III tubulin and Masson trichrome staining were used as to evaluate nerve sprouting, matrix tension, and degeneration in the tendon. Of fourteen analyzed parameters, RF significantly improved stance phase, step length, preswing, and intermediary toe-spread of gait. Improved gait related to the expression of substance P, CGRP, and reduced nerve fiber sprouting and matrix tension, but not galanin. The study indicates that direct RF application may be a valuable approach to improve gait and pain in acute tendon injury. Altered gait parameters may be used as references to evaluate therapeutic outcomes of RF or other treatment plan for tendinopathy.

  4. A Comparative Evaluation of Gait between Children with Autism and Typically Developing Matched Controls

    Janet S. Dufek

    2017-01-01

    Full Text Available Anecdotal reports suggest children with autism spectrum disorder (ASD ambulate differently than peers with typical development (TD. Little empirical evidence supports these reports. Children with ASD exhibit delayed motor skills, and it is important to determine whether or not motor movement deficits exist during walking. The purpose of the study was to perform a comprehensive lower-extremity gait analysis between children (aged 5–12 years with ASD and age- and gender-matched-samples with TD. Gait parameters were normalized to 101 data points and the gait cycle was divided into seven sub-phases. The Model Statistic procedure was used to test for statistical significance between matched-pairs throughout the entire gait cycle for each parameter. When collapsed across all participants, children with ASD exhibited large numbers of significant differences (p < 0.05 throughout the gait cycle in hip, knee, and ankle joint positions as well as vertical and anterior/posterior ground reaction forces. Children with ASD exhibited unique differences throughout the gait cycle, which supports current literature on the heterogeneity of the disorder. The present work supports recent findings that motor movement differences may be a core symptom of ASD. Thus, individuals may benefit from therapeutic movement interventions that follow precision medicine guidelines by accounting for individual characteristics, given the unique movement differences observed.

  5. Shotgun approaches to gait analysis : insights & limitations

    Kaptein, Ronald G.; Wezenberg, Daphne; IJmker, Trienke; Houdijk, Han; Beek, Peter J.; Lamoth, Claudine J. C.; Daffertshofer, Andreas

    2014-01-01

    Background: Identifying features for gait classification is a formidable problem. The number of candidate measures is legion. This calls for proper, objective criteria when ranking their relevance. Methods: Following a shotgun approach we determined a plenitude of kinematic and physiological gait

  6. [Subjective Gait Stability in the Elderly].

    Hirsch, Theresa; Lampe, Jasmin; Michalk, Katrin; Röder, Lotte; Munsch, Karoline; Marquardt, Jonas

    2017-07-10

    It can be assumed that the feeling of gait stability or gait instability in the elderly may be independent of a possible fear of falling or a history of falling when walking. Up to now, there has been a lack of spatiotemporal gait parameters for older people who subjectively feel secure when walking. The aim of the study is to analyse the distribution of various gait parameters for older people who subjectively feel secure when walking. In a cross-sectional study, the gait parameters stride time, step time, stride length, step length, double support, single support, and walking speed were measured using a Vicon three-dimensional motion capture system (Plug-In Gait Lower-Body Marker Set) in 31 healthy people aged 65 years and older (mean age 72 ± 3.54 years) who subjectively feel secure when walking. There was a homogeneous distribution in the gait parameters examined, with no abnormalities. The mean values have a low variance with narrow confidence intervals. This study provides evidence that people who subjectively feel secure when walking demonstrate similarly objective gait parameters..

  7. Gait analysis by high school students

    Heck, A.; van Dongen, C.

    2008-01-01

    Human walking is a complicated motion. Movement scientists have developed various research methods to study gait. This article describes how a high school student collected and analysed high quality gait data in much the same way that movement scientists do, via the recording and measurement of

  8. The dual task effect on gait in adults with intellectual disabilities: is it predictive for falls?

    Oppewal, Alyt; Hilgenkamp, Thessa I M

    2017-09-03

    Falling is an important health issue in adults with intellectual disabilities. Their cognitive and motor limitations may result in difficulties with dual tasking (walking and talking), which increases fall risk. Therefore, we assessed the dual task effect on gait in adults with intellectual disabilities, if this dual task effect is predictive for falls, and if this is more predictive than regular walking. Gait characteristics of 31 adults with intellectual disabilities without Down syndrome were assessed with the GAITRite at comfortable speed and during dual tasking (conversation). Falls were collected over a three-month follow-up period. During dual tasking, participants walked slower, with a lower cadence, increased stride time, and shorter stride lengths. They spend less time in swing and single support phase than at comfortable speed. Also swing and single support time became more variable. The dual task effect and walking at comfortable speed were not predictive for falls, although medium effect sizes were found. Dual tasking affects gait in adults with intellectual disabilities. This is an important finding for safe community participation, and must be considered while interacting with adults with intellectual disabilities during daily activities. Possible negative consequences of distractors should be kept in mind. More research is needed to better understand the predictive value of gait for falls. Implications for Rehabilitation Having a conversation while walking affects the gait pattern of adults with intellectual disabilities, possible negative consequences of distractors should be kept in mind. The dual task effect on the width of the gait pattern and stride time variability had the largest effect sizes with future falls, this potential relationship should be kept in mind in clinical practice. The dual task effect on gait is important to consider with regard to safe community participation. Future studies are needed to better understand the predictive

  9. Cell cycle G2/M arrest through an S phase-dependent mechanism by HIV-1 viral protein R.

    Li, Ge; Park, Hyeon U; Liang, Dong; Zhao, Richard Y

    2010-07-07

    Cell cycle G2 arrest induced by HIV-1 Vpr is thought to benefit viral proliferation by providing an optimized cellular environment for viral replication and by skipping host immune responses. Even though Vpr-induced G2 arrest has been studied extensively, how Vpr triggers G2 arrest remains elusive. To examine this initiation event, we measured the Vpr effect over a single cell cycle. We found that even though Vpr stops the cell cycle at the G2/M phase, but the initiation event actually occurs in the S phase of the cell cycle. Specifically, Vpr triggers activation of Chk1 through Ser345 phosphorylation in an S phase-dependent manner. The S phase-dependent requirement of Chk1-Ser345 phosphorylation by Vpr was confirmed by siRNA gene silencing and site-directed mutagenesis. Moreover, downregulation of DNA replication licensing factors Cdt1 by siRNA significantly reduced Vpr-induced Chk1-Ser345 phosphorylation and G2 arrest. Even though hydroxyurea (HU) and ultraviolet light (UV) also induce Chk1-Ser345 phosphorylation in S phase under the same conditions, neither HU nor UV-treated cells were able to pass through S phase, whereas vpr-expressing cells completed S phase and stopped at the G2/M boundary. Furthermore, unlike HU/UV, Vpr promotes Chk1- and proteasome-mediated protein degradations of Cdc25B/C for G2 induction; in contrast, Vpr had little or no effect on Cdc25A protein degradation normally mediated by HU/UV. These data suggest that Vpr induces cell cycle G2 arrest through a unique molecular mechanism that regulates host cell cycle regulation in an S-phase dependent fashion.

  10. Cell cycle G2/M arrest through an S phase-dependent mechanism by HIV-1 viral protein R

    Liang Dong

    2010-07-01

    Full Text Available Abstract Background Cell cycle G2 arrest induced by HIV-1 Vpr is thought to benefit viral proliferation by providing an optimized cellular environment for viral replication and by skipping host immune responses. Even though Vpr-induced G2 arrest has been studied extensively, how Vpr triggers G2 arrest remains elusive. Results To examine this initiation event, we measured the Vpr effect over a single cell cycle. We found that even though Vpr stops the cell cycle at the G2/M phase, but the initiation event actually occurs in the S phase of the cell cycle. Specifically, Vpr triggers activation of Chk1 through Ser345 phosphorylation in an S phase-dependent manner. The S phase-dependent requirement of Chk1-Ser345 phosphorylation by Vpr was confirmed by siRNA gene silencing and site-directed mutagenesis. Moreover, downregulation of DNA replication licensing factors Cdt1 by siRNA significantly reduced Vpr-induced Chk1-Ser345 phosphorylation and G2 arrest. Even though hydroxyurea (HU and ultraviolet light (UV also induce Chk1-Ser345 phosphorylation in S phase under the same conditions, neither HU nor UV-treated cells were able to pass through S phase, whereas vpr-expressing cells completed S phase and stopped at the G2/M boundary. Furthermore, unlike HU/UV, Vpr promotes Chk1- and proteasome-mediated protein degradations of Cdc25B/C for G2 induction; in contrast, Vpr had little or no effect on Cdc25A protein degradation normally mediated by HU/UV. Conclusions These data suggest that Vpr induces cell cycle G2 arrest through a unique molecular mechanism that regulates host cell cycle regulation in an S-phase dependent fashion.

  11. Flexible Piezoelectric Sensor-Based Gait Recognition

    Youngsu Cha

    2018-02-01

    Full Text Available Most motion recognition research has required tight-fitting suits for precise sensing. However, tight-suit systems have difficulty adapting to real applications, because people normally wear loose clothes. In this paper, we propose a gait recognition system with flexible piezoelectric sensors in loose clothing. The gait recognition system does not directly sense lower-body angles. It does, however, detect the transition between standing and walking. Specifically, we use the signals from the flexible sensors attached to the knee and hip parts on loose pants. We detect the periodic motion component using the discrete time Fourier series from the signal during walking. We adapt the gait detection method to a real-time patient motion and posture monitoring system. In the monitoring system, the gait recognition operates well. Finally, we test the gait recognition system with 10 subjects, for which the proposed system successfully detects walking with a success rate over 93 %.

  12. Average Gait Differential Image Based Human Recognition

    Jinyan Chen

    2014-01-01

    Full Text Available The difference between adjacent frames of human walking contains useful information for human gait identification. Based on the previous idea a silhouettes difference based human gait recognition method named as average gait differential image (AGDI is proposed in this paper. The AGDI is generated by the accumulation of the silhouettes difference between adjacent frames. The advantage of this method lies in that as a feature image it can preserve both the kinetic and static information of walking. Comparing to gait energy image (GEI, AGDI is more fit to representation the variation of silhouettes during walking. Two-dimensional principal component analysis (2DPCA is used to extract features from the AGDI. Experiments on CASIA dataset show that AGDI has better identification and verification performance than GEI. Comparing to PCA, 2DPCA is a more efficient and less memory storage consumption feature extraction method in gait based recognition.

  13. Gait and Function in Class III Obesity

    Catherine Ling

    2012-01-01

    Full Text Available Walking, more specifically gait, is an essential component of daily living. Walking is a very different activity for individuals with a Body Mass Index (BMI of 40 or more (Class III obesity compared with those who are overweight or obese with a BMI between 26–35. Yet all obesity weight classes receive the same physical activity guidelines and recommendations. This observational study examined the components of function and disability in a group with Class III obesity and a group that is overweight or has Class I obesity. Significant differences were found between the groups in the areas of gait, body size, health condition, and activity capacity and participation. The Timed Up and Go test, gait velocity, hip circumference, and stance width appear to be most predictive of activity capacity as observed during gait assessment. The findings indicate that Class III-related gait is pathologic and not a normal adaptation.

  14. Dependence of Polarization of the near-Earth Asteroids (1036) Ganymed and (5143) Heracles on Wavelength and Phase Angle

    Maleszewski, C.; McMillan, R.; Smith, P.

    2012-12-01

    We are measuring the polarization of asteroids with the SPOL polarimeter of Steward Observatory. With monthly access to the instrument, we can obtain many observations throughout phase angle. This is in contrast to other recent work that had to rely on aggregate properties of targets of similar taxonomic type. Comparing individual objects to these aggregate results may reveal differences of regolith properties from object to object. Both the phase angle and spectral dependence of polarization are being measured. SPOL provides simultaneous coverage from 0.40-0.75 microns, equivalent to BVR filters. Three phase curves thus reveal differences of phase angle dependences with respect to wavelength. The spectral dependence of the linear polarization is determined according to a linear trend previously used to describe the dependence for Main Belt Asteroids (MBAs) in various taxonomic classes (Belskaya et al. 2009). The slopes of these linear trends vs. phase angle are also investigated as was also done in the Belskaya analysis for MBAs in the C-, M-, and S-types. Two initial objects of interest are the NEAs (1036) Ganymed and (5143) Heracles. The taxonomic types of Ganymed and Heracles are S-type and Q-type respectively (DeMeo et al. 2009). For Ganymed, twelve observations were made between 2011 September and 2012 March. These include observations below ten degrees phase angle, which are currently lacking in the polarimetric databases. The positive branch of Ganymed's polarization phase curve behaved similarly across SPOL's wavelength range. But for wavelengths associated with a typical B-filter, the negative branch is more shallow and narrow. The negative phase branch of Ganymed is smaller compared to the aggregate phase curve of S-types determined by Gil-Hutton and Cañada-Assandri (2011). The linear polarization decreases with increasing wavelength at all observed phase angles. As the phase angle increases, the slope of the wavelength dependence of polarization

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

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

    2017-11-01

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

  16. Markedly impaired bilateral coordination of gait in post-stroke patients: Is this deficit distinct from asymmetry? A cohort study

    van Lummel Rob C

    2011-05-01

    Full Text Available Abstract Background Multiple aspects of gait are typically impaired post-stroke. Asymmetric gait is common as a consequence of unilateral brain lesions. The relationship between the resulting asymmetric gait and impairments in the ability to properly coordinate the reciprocal stepping activation of the legs is not clear. The objective of this exploratory study is to quantify the effects of hemiparesis on two putatively independent aspects of the bilateral coordination of gait to gain insight into mechanisms and their relationship and to assess their potential as clinical markers. Methods Twelve ambulatory stroke patients and age-matched healthy adults wore a tri-axial piezo-resistive accelerometer and walked back and forth along a straight path in a hall at a comfortable walking speed during 2 minutes. Gait speed, gait asymmetry (GA, and aspects of the bilateral coordination of gait (BCG were determined. Bilateral coordination measures included the left-right stepping phase for each stride φi, consistency in the phase generation φ_CV, accuracy in the phase generation φ_ABS, and Phase Coordination Index (PCI, a combination of accuracy and consistency of the phase generation. Results Group differences (p Conclusions In ambulatory post-stroke patients, two gait coordination properties, GA and PCI, are markedly impaired. Although these features are not related to each other in healthy controls, they are strongly related in stroke patients, which is a novel finding. A measurement approach based on body-fixed sensors apparently may provide sensitive markers that can be used for clinical assessment and for enhancing rehabilitation targeting in post-stroke patients.

  17. Markedly impaired bilateral coordination of gait in post-stroke patients: Is this deficit distinct from asymmetry? A cohort study

    2011-01-01

    Background Multiple aspects of gait are typically impaired post-stroke. Asymmetric gait is common as a consequence of unilateral brain lesions. The relationship between the resulting asymmetric gait and impairments in the ability to properly coordinate the reciprocal stepping activation of the legs is not clear. The objective of this exploratory study is to quantify the effects of hemiparesis on two putatively independent aspects of the bilateral coordination of gait to gain insight into mechanisms and their relationship and to assess their potential as clinical markers. Methods Twelve ambulatory stroke patients and age-matched healthy adults wore a tri-axial piezo-resistive accelerometer and walked back and forth along a straight path in a hall at a comfortable walking speed during 2 minutes. Gait speed, gait asymmetry (GA), and aspects of the bilateral coordination of gait (BCG) were determined. Bilateral coordination measures included the left-right stepping phase for each stride φi, consistency in the phase generation φ_CV, accuracy in the phase generation φ_ABS, and Phase Coordination Index (PCI), a combination of accuracy and consistency of the phase generation. Results Group differences (p stroke patients (r = 0.94; p stroke patients, two gait coordination properties, GA and PCI, are markedly impaired. Although these features are not related to each other in healthy controls, they are strongly related in stroke patients, which is a novel finding. A measurement approach based on body-fixed sensors apparently may provide sensitive markers that can be used for clinical assessment and for enhancing rehabilitation targeting in post-stroke patients. PMID:21545703

  18. Determining Role of the Chain Mechanism in the Temperature Dependence of the Gas-Phase Rate of Combustion Reactions

    Azatyan, V. V.; Bolod'yan, I. A.; Kopylov, N. P.; Kopylov, S. N.; Prokopenko, V. M.; Shebeko, Yu. N.

    2018-05-01

    It is shown that the strong dependence of the rate of gas-phase combustion reactions on temperature is determined by the high values of the reaction rate constants of free atoms and radicals. It is established that with a branched chain mechanism, a special role in the reaction rate temperature dependence is played by positive feedback between the concentrations of active intermediate species and the rate of their change. The role of the chemical mechanism in the temperature dependence of the process rate with and without inhibitors is considered.

  19. Method for Walking Gait Identification in a Lower Extremity Exoskeleton Based on C4.5 Decision Tree Algorithm

    Qing Guo

    2015-04-01

    Full Text Available A gait identification method for a lower extremity exoskeleton is presented in order to identify the gait sub-phases in human-machine coordinated motion. First, a sensor layout for the exoskeleton is introduced. Taking the difference between human lower limb motion and human-machine coordinated motion into account, the walking gait is divided into five sub-phases, which are ‘double standing’, ‘right leg swing and left leg stance’, ‘double stance with right leg front and left leg back’, ‘right leg stance and left leg swing’, and ‘double stance with left leg front and right leg back’. The sensors include shoe pressure sensors, knee encoders, and thigh and calf gyroscopes, and are used to measure the contact force of the foot, and the knee joint angle and its angular velocity. Then, five sub-phases of walking gait are identified by a C4.5 decision tree algorithm according to the data fusion of the sensors' information. Based on the simulation results for the gait division, identification accuracy can be guaranteed by the proposed algorithm. Through the exoskeleton control experiment, a division of five sub-phases for the human-machine coordinated walk is proposed. The experimental results verify this gait division and identification method. They can make hydraulic cylinders retract ahead of time and improve the maximal walking velocity when the exoskeleton follows the person's motion.

  20. Immediate effects of a single session of robot-assisted gait training using Hybrid Assistive Limb (HAL) for cerebral palsy.

    Matsuda, Mayumi; Mataki, Yuki; Mutsuzaki, Hirotaka; Yoshikawa, Kenichi; Takahashi, Kazushi; Enomoto, Keiko; Sano, Kumiko; Mizukami, Masafumi; Tomita, Kazuhide; Ohguro, Haruka; Iwasaki, Nobuaki

    2018-02-01

    [Purpose] Robot-assisted gait training (RAGT) using Hybrid Assistive Limb (HAL, CYBERDYNE) was previously reported beneficial for stroke and spinal cord injury patients. Here, we investigate the immediate effect of a single session of RAGT using HAL on gait function for cerebral palsy (CP) patients. [Subjects and Methods] Twelve patients (average age: 16.2 ± 7.3 years) with CP received a single session of RAGT using HAL. Gait speed, step length, cadence, single-leg support per gait cycle, hip and knee joint angle in stance, and swing phase per gait cycle were assessed before, during, and immediately after HAL intervention. [Results] Compared to baseline values, single-leg support per gait cycle (64.5 ± 15.8% to 69.3 ± 12.1%), hip extension angle in mid-stance (149.2 ± 19.0° to 155.5 ± 20.1°), and knee extension angle in mid-stance (137.6 ± 20.2° to 143.1 ± 19.5°) were significantly increased immediately after intervention. Further, the knee flexion angle in mid-swing was significantly decreased immediately after treatment (112.0 ± 15.5° to 105.2 ± 17.1°). Hip flexion angle in mid-swing also decreased following intervention (137.2 ± 14.6° to 129.7 ± 16.6°), but not significantly. Conversely, gait speed, step length, and cadence were unchanged after intervention. [Conclusion] A single-time RAGT with HAL improved single-leg support per gait cycle and hip and knee joint angle during gait, therapeutically improving gait function in CP patients.

  1. Statistical Parametric Mapping to Identify Differences between Consensus-Based Joint Patterns during Gait in Children with Cerebral Palsy.

    Nieuwenhuys, Angela; Papageorgiou, Eirini; Desloovere, Kaat; Molenaers, Guy; De Laet, Tinne

    2017-01-01

    Experts recently identified 49 joint motion patterns in children with cerebral palsy during a Delphi consensus study. Pattern definitions were therefore the result of subjective expert opinion. The present study aims to provide objective, quantitative data supporting the identification of these consensus-based patterns. To do so, statistical parametric mapping was used to compare the mean kinematic waveforms of 154 trials of typically developing children (n = 56) to the mean kinematic waveforms of 1719 trials of children with cerebral palsy (n = 356), which were classified following the classification rules of the Delphi study. Three hypotheses stated that: (a) joint motion patterns with 'no or minor gait deviations' (n = 11 patterns) do not differ significantly from the gait pattern of typically developing children; (b) all other pathological joint motion patterns (n = 38 patterns) differ from typically developing gait and the locations of difference within the gait cycle, highlighted by statistical parametric mapping, concur with the consensus-based classification rules. (c) all joint motion patterns at the level of each joint (n = 49 patterns) differ from each other during at least one phase of the gait cycle. Results showed that: (a) ten patterns with 'no or minor gait deviations' differed somewhat unexpectedly from typically developing gait, but these differences were generally small (≤3°); (b) all other joint motion patterns (n = 38) differed from typically developing gait and the significant locations within the gait cycle that were indicated by the statistical analyses, coincided well with the classification rules; (c) joint motion patterns at the level of each joint significantly differed from each other, apart from two sagittal plane pelvic patterns. In addition to these results, for several joints, statistical analyses indicated other significant areas during the gait cycle that were not included in the pattern definitions of the consensus study

  2. Effects of Dual-Channel Functional Electrical Stimulation on Gait Performance in Patients with Hemiparesis

    Springer, Shmuel; Vatine, Jean-Jacques; Lipson, Ronit; Wolf, Alon; Laufer, Yocheved

    2012-01-01

    The study objective was to assess the effect of functional electrical stimulation (FES) applied to the peroneal nerve and thigh muscles on gait performance in subjects with hemiparesis. Participants were 45 subjects (age 57.8 ± 14.8 years) with hemiparesis (5.37 ± 5.43 years since diagnosis) demonstrating a foot-drop and impaired knee control. Thigh stimulation was applied either to the quadriceps or hamstrings muscles, depending on the dysfunction most affecting gait. Gait was assessed during a two-minute walk test with/without stimulation and with peroneal stimulation alone. A second assessment was conducted after six weeks of daily use. The addition of thigh muscles stimulation to peroneal stimulation significantly enhanced gait velocity measures at the initial and second evaluation. Gait symmetry was enhanced by the dual-channel stimulation only at the initial evaluation, and single-limb stance percentage only at the second assessment. For example, after six weeks, the two-minute gait speed with peroneal stimulation and with the dual channel was 0.66 ± 0.30 m/sec and 0.70 ± 0.31 m/sec, respectively (P hemiparesis more than peroneal FES alone. PMID:23097635

  3. Neuromuscular adjustments of gait associated with unstable conditions

    Ivanenko, Y. P.; d'Avella, A.; Serrao, M.; Ranavolo, A.; Draicchio, F.; Cappellini, G.; Casali, C.; Lacquaniti, F.

    2015-01-01

    A compact description of coordinated muscle activity is provided by the factorization of electromyographic (EMG) signals. With the use of this approach, it has consistently been shown that multimuscle activity during human locomotion can be accounted for by four to five modules, each one comprised of a basic pattern timed at a different phase of gait cycle and the weighting coefficients of synergistic muscle activations. These modules are flexible, in so far as the timing of patterns and the amplitude of weightings can change as a function of gait speed and mode. Here we consider the adjustments of the locomotor modules related to unstable walking conditions. We compared three different conditions, i.e., locomotion of healthy subjects on slippery ground (SL) and on narrow beam (NB) and of cerebellar ataxic (CA) patients on normal ground. Motor modules were computed from the EMG signals of 12 muscles of the right lower limb using non-negative matrix factorization. The unstable gait of SL, NB, and CA showed significant changes compared with controls in the stride length, stride width, range of angular motion, and trunk oscillations. In most subjects of all three unstable conditions, >70% of the overall variation of EMG waveforms was accounted for by four modules that were characterized by a widening of muscle activity patterns. This suggests that the nervous system adopts the strategy of prolonging the duration of basic muscle activity patterns to cope with unstable conditions resulting from either slippery ground, reduced support surface, or pathology. PMID:26378199

  4. System of gait analysis based on ground reaction force assessment

    František Vaverka

    2015-12-01

    Full Text Available Background: Biomechanical analysis of gait employs various methods used in kinematic and kinetic analysis, EMG, and others. One of the most frequently used methods is kinetic analysis based on the assessment of the ground reaction forces (GRF recorded on two force plates. Objective: The aim of the study was to present a method of gait analysis based on the assessment of the GRF recorded during the stance phase of two steps. Methods: The GRF recorded with a force plate on one leg during stance phase has three components acting in directions: Fx - mediolateral, Fy - anteroposterior, and Fz - vertical. A custom-written MATLAB script was used for gait analysis in this study. This software displays instantaneous force data for both legs as Fx(t, Fy(t and Fz(t curves, automatically determines the extremes of functions and sets the visual markers defining the individual points of interest. Positions of these markers can be easily adjusted by the rater, which may be necessary if the GRF has an atypical pattern. The analysis is fully automated and analyzing one trial takes only 1-2 minutes. Results: The method allows quantification of temporal variables of the extremes of the Fx(t, Fy(t, Fz(t functions, durations of the braking and propulsive phase, duration of the double support phase, the magnitudes of reaction forces in extremes of measured functions, impulses of force, and indices of symmetry. The analysis results in a standardized set of 78 variables (temporal, force, indices of symmetry which can serve as a basis for further research and diagnostics. Conclusions: The resulting set of variable offers a wide choice for selecting a specific group of variables with consideration to a particular research topic. The advantage of this method is the standardization of the GRF analysis, low time requirements allowing rapid analysis of a large number of trials in a short time, and comparability of the variables obtained during different research measurements.

  5. Bias dependent specic contact resistance of phase change material to metal contacts

    Roy, Deepu; in 't Zandt, Micha; Wolters, Robertus A.M.

    2010-01-01

    Knowledge of contact resistance of phase change materials (PCM) to metal electrodes is important for scaling, device modeling and optimization of phase change random access memory (PCRAM) cells. In this article, we report the systematic determination of the speci_c contact resistance (_c) with

  6. Phase-dependent deterministic switching of magnetoelectric spin wave detector in the presence of thermal noise via compensation of demagnetization

    Dutta, Sourav, E-mail: sdutta38@gatech.edu; Naeemi, Azad [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Nikonov, Dmitri E.; Manipatruni, Sasikanth; Young, Ian A. [Components Research, Intel Corporation, Hillsboro, Oregon 97124 (United States)

    2015-11-09

    The possibility of achieving phase-dependent deterministic switching of the magnetoelectric spin wave detector in the presence of thermal noise has been discussed. The proposed idea relies on the modification of the energy landscape by partially canceling the out-of-plane demagnetizing field and the resultant change in the intrinsic magnetization dynamics to drive the nanomagnet towards a preferential final magnetization state. The remarkable increase in the probability of successful switching can be accounted for by the shift in the location of the saddle point in the energy landscape and a resultant change in the nature of the relaxation dynamics of the magnetization from a highly precessional to a fairly damped one and an increased dependence on the initial magnetization values, a crucial requirement for phase-dependent spin wave detection.

  7. Comparison of the Classifier Oriented Gait Score and the Gait Profile Score based on imitated gait impairments.

    Christian, Josef; Kröll, Josef; Schwameder, Hermann

    2017-06-01

    Common summary measures of gait quality such as the Gait Profile Score (GPS) are based on the principle of measuring a distance from the mean pattern of a healthy reference group in a gait pattern vector space. The recently introduced Classifier Oriented Gait Score (COGS) is a pathology specific score that measures this distance in a unique direction, which is indicated by a linear classifier. This approach has potentially improved the discriminatory power to detect subtle changes in gait patterns but does not incorporate a profile of interpretable sub-scores like the GPS. The main aims of this study were to extend the COGS by decomposing it into interpretable sub-scores as realized in the GPS and to compare the discriminative power of the GPS and COGS. Two types of gait impairments were imitated to enable a high level of control of the gait patterns. Imitated impairments were realized by restricting knee extension and inducing leg length discrepancy. The results showed increased discriminatory power of the COGS for differentiating diverse levels of impairment. Comparison of the GPS and COGS sub-scores and their ability to indicate changes in specific variables supports the validity of both scores. The COGS is an overall measure of gait quality with increased power to detect subtle changes in gait patterns and might be well suited for tracing the effect of a therapeutic treatment over time. The newly introduced sub-scores improved the interpretability of the COGS, which is helpful for practical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Dynamic phase diagrams of a cylindrical Ising nanowire in the presence of a time dependent magnetic field

    Kantar, Ersin; Ertaş, Mehmet; Keskin, Mustafa

    2014-01-01

    The dynamic phase diagrams of a cylindrical Ising nanowire in the presence of a time dependent magnetic field are obtained by using the effective-field theory with correlations based on the Glauber-type stochastic dynamics. According to the values of interaction parameters, a number of interesting properties have been found in the dynamic phase diagrams, such as many dynamic critical points (tricritical point, double critical end point, critical end point, zero temperature critical point, multicritical point, tetracritical point, and triple point) as well as reentrant phenomena. - Highlights: • The cylindrical Ising nanowire is investigated within the Glauber dynamics based on EFT. • The time variations of average order parameters to find phases are studied. • The dynamic phase diagrams are found for the different interaction parameters. • The system displays the critical points as well as a reentrant behavior

  9. Dynamic phase diagrams of a cylindrical Ising nanowire in the presence of a time dependent magnetic field

    Kantar, Ersin; Ertaş, Mehmet, E-mail: mehmetertas@erciyes.edu.tr; Keskin, Mustafa

    2014-06-01

    The dynamic phase diagrams of a cylindrical Ising nanowire in the presence of a time dependent magnetic field are obtained by using the effective-field theory with correlations based on the Glauber-type stochastic dynamics. According to the values of interaction parameters, a number of interesting properties have been found in the dynamic phase diagrams, such as many dynamic critical points (tricritical point, double critical end point, critical end point, zero temperature critical point, multicritical point, tetracritical point, and triple point) as well as reentrant phenomena. - Highlights: • The cylindrical Ising nanowire is investigated within the Glauber dynamics based on EFT. • The time variations of average order parameters to find phases are studied. • The dynamic phase diagrams are found for the different interaction parameters. • The system displays the critical points as well as a reentrant behavior.

  10. Phase-dependent preference of thermosensation and chemosensation during simultaneous presentation assay in Caenorhabditis elegans

    Shingai Ryuzo

    2008-11-01

    presentation was faster than that in 15°C-single presentation. Conclusion We conclude that worms preferred temperature to chemoattractant at first, but preferred the chemoattractant sodium chloride thereafter. This preference was not seen for isoamyl alcohol presentation. We attribute this phase-dependent preference to the result of integration of thermosensory and chemosensory signals received by distinct sensory neurons.

  11. Brain mapping for long-term recovery of gait after supratentorial stroke: A retrospective cross-sectional study.

    Kim, Dae Hyun; Kyeong, Sunghyon; Do, Kyung Hee; Lim, Seong Kyu; Cho, Hyong Keun; Jung, Suk; Kim, Hye Won

    2018-04-01

    The recovery of independent gait after stroke is a main goal of patients and understanding the relationship between brain lesions and the recovery of gait can help physicians set viable rehabilitation plans. Our study investigated the association between variables of gait parameters and brain lesions.Fifty poststroke patients with a mean age of 67.5 ± 1.3 years and an average duration after onset of 62.2 ± 7.9 months were included. Three-dimensional gait analysis and magnetic resonance imaging were conducted for all patients. Twelve quantified gait parameters of temporal-spatial, kinematic, and kinetic data were used. To correlate gait parameters with specific brain lesions, we used a voxel-based lesion symptom mapping analysis. Statistical significance was set to an uncorrected P value 10 voxels.Based on the location of a brain lesion, the following results were obtained: The posterior limb of the internal capsule was significantly associated with gait speed and increased knee extension in the stance phase. The hippocampus and frontal lobe were significantly associated with cadence. The proximal corona radiata was significantly associated with stride length and affected the hip maximal extension angle in the stance phase. The paracentral lobule was significantly associated with the affected knee maximal flexion angle in the swing phase and with the affected ankle maximal dorsiflexion angle in the stance phase. The frontal lobe, thalamus, and the lentiform nucleus were associated with kinetic gait parameters.Cortical, proximal white matter, and learning-related and motor-related areas are mainly associated with one's walking ability after stroke.

  12. Temperature-dependent thermal properties of a paraffin phase change material embedded with herringbone style graphite nanofibers

    Warzoha, Ronald J.; Weigand, Rebecca M.; Fleischer, Amy S.

    2015-01-01

    Highlights: • The thermal properties of a PCM with nanofibers are determined. • The solid-phase thermal conductivity scales exponentially with volume fraction. • The liquid-phase thermal conductivity is only enhanced beyond a critical percolation threshold. • The nanoscale interface resistance depends on the nanoparticle’s dimensionality. • The thermal diffusivity and volumetric heat capacity of the nanoenhanced PCMs are found. - Abstract: In many studies, carbon nanoparticles with high values of thermal conductivity (10–3000 W/m K) have been embedded into phase change thermal energy storage materials (PCMs) in order to enhance their bulk thermal properties. While a great deal of work to date has focused on determining the effect of these nanoparticles on a PCM’s solid phase thermal properties, little is known about their effect on its liquid phase thermal properties. Thus, in this study, the effect of implanting randomly oriented herringbone style graphite nanofibers (HGNF, average diameter = 100 nm, average length = 20 μm) on the bulk thermal properties of an organic paraffin PCM (IGI 1230A, T melt = 329.15 K) in both the solid and liquid phase is quantified. The bulk thermal conductivity, volumetric heat capacity and thermal diffusivity of HGNF/PCM nanocomposites are obtained as a function of temperature and HGNF volume loading level. It is found that the property enhancement varies significantly depending on the material phase. In order to explain the difference between solid and liquid phase thermal properties, heat flow at the nanoparticle–PCM and nanoparticle–nanoparticle interfaces is examined as a function of HGNF loading level and temperature. To do this, the solid and liquid phase thermal boundary resistances (TBRs) between the nanoparticles and the surrounding PCM and/or between contacting nanoparticles are found. Results suggest that the TBR at the HGNF–PCM interface is nearly double the TBR across the HGNF–HGNF interface in

  13. Amide-induced phase separation of hexafluoroisopropanol-water mixtures depending on the hydrophobicity of amides.

    Takamuku, Toshiyuki; Wada, Hiroshi; Kawatoko, Chiemi; Shimomura, Takuya; Kanzaki, Ryo; Takeuchi, Munetaka

    2012-06-21

    Amide-induced phase separation of hexafluoro-2-propanol (HFIP)-water mixtures has been investigated to elucidate solvation properties of the mixtures by means of small-angle neutron scattering (SANS), (1)H and (13)C NMR, and molecular dynamics (MD) simulation. The amides included N-methylformamide (NMF), N-methylacetamide (NMA), and N-methylpropionamide (NMP). The phase diagrams of amide-HFIP-water ternary systems at 298 K showed that phase separation occurs in a closed-loop area of compositions as well as an N,N-dimethylformamide (DMF) system previously reported. The phase separation area becomes wider as the hydrophobicity of amides increases in the order of NMF amides due to the hydrophobic interaction gives rise to phase separation of the mixtures. In contrast, the disruption of HFIP clusters causes the recovery of the homogeneity of the ternary systems. The present results showed that HFIP clusters are evolved with increasing amide content to the lower phase separation concentration in the same mechanism among the four amide systems. However, the disruption of HFIP clusters in the NMP and DMF systems with further increasing amide content to the upper phase separation concentration occurs in a different way from those in the NMF and NMA systems.

  14. Effects of Quadriceps Muscle Fatigue on Stiff-Knee Gait in Patients with Hemiparesis

    Boudarham, Julien; Roche, Nicolas; Pradon, Didier; Delouf, Eric; Bensmail, Djamel; Zory, Raphael

    2014-01-01

    The relationship between neuromuscular fatigue and locomotion has never been investigated in hemiparetic patients despite the fact that, in the clinical context, patients report to be more spastic or stiffer after walking a long distance or after a rehabilitation session. The aim of this study was to evaluate the effects of quadriceps muscle fatigue on the biomechanical gait parameters of patients with a stiff-knee gait (SKG). Thirteen patients and eleven healthy controls performed one gait analysis before a protocol of isokinetic quadriceps fatigue and two after (immediately after and after 10 minutes of rest). Spatiotemporal parameters, sagittal knee and hip kinematics, rectus femoris (RF) and vastus lateralis (VL) kinematics and electromyographic (EMG) activity were analyzed. The results showed that quadriceps muscle weakness, produced by repetitive concentric contractions of the knee extensors, induced an improvement of spatiotemporal parameters for patients and healthy subjects. For the patient group, the increase in gait velocity and step length was associated with i) an increase of sagittal hip and knee flexion during the swing phase, ii) an increase of the maximal normalized length of the RF and VL and of the maximal VL lengthening velocity during the pre-swing and swing phases, and iii) a decrease in EMG activity of the RF muscle during the initial pre-swing phase and during the latter 2/3 of the initial swing phase. These results suggest that quadriceps fatigue did not alter the gait of patients with hemiparesis walking with a SKG and that neuromuscular fatigue may play the same functional role as an anti-spastic treatment such as botulinum toxin-A injection. Strength training of knee extensors, although commonly performed in rehabilitation, does not seem to be a priority to improve gait of these patients. PMID:24718087

  15. Response of the arterial blood pressure of quadriplegic patients to treadmill gait training

    D.C.L. Carvalho

    2005-09-01

    Full Text Available Blood pressure pattern was analyzed in 12 complete quadriplegics with chronic lesions after three months of treadmill gait training. Before training, blood pressure values were obtained at rest, during treadmill walking and during the recovery phase. Gait training was performed for 20 min twice a week for three months. Treadmill gait was achieved using neuromuscular electrical stimulation, assisted by partial body weight relief (30-50%. After training, blood pressure was evaluated at rest, during gait and during recovery phase. Before and after training, mean systolic blood pressures and heart rates increased significantly during gait compared to rest (94.16 ± 5.15 to 105 ± 5.22 mmHg and 74.27 ± 10.09 to 106.23 ± 17.31 bpm, respectively, and blood pressure decreased significantly in the recovery phase (86.66 ± 9.84 and 57.5 ± 8.66 mmHg, respectively. After three months of training, systolic blood pressure became higher at rest (94.16 ± 5.15 mmHg before training and 100 ± 8.52 mmHg after training; P < 0.05 and during gait exercise (105 ± 5.22 mmHg before and 110 ± 7.38 mmHg after training; P < 0.05 when compared to the initial values, with no changes in heart rate. No changes occurred in blood pressure during the recovery phase, with the lower values being maintained. A drop in systolic pressure from 105 ± 5.22 to 86.66 ± 9.84 mmHg before training and from 110 ± 7.38 to 90 ± 7.38 mmHg after training was noticed immediately after exercise, thus resulting in hypotensive symptoms when chronic quadriplegics reach the sitting position from the upright position.

  16. Influence of velocity on variability in gait kinematics: implications for recognition in forensic science.

    Yang, Sylvia X M; Larsen, Peter K; Alkjaer, Tine; Lynnerup, Niels; Simonsen, Erik B

    2014-09-01

    Closed circuit television (CCTV) footage is often available from crime scenes and may be used to compare perpetrators with suspects. Usually, the footage comprises incomplete gait cycles at different velocities, making gait pattern identification from crimes difficult. This study investigated the concurrence of joint angles throughout a gait cycle at three different velocities (3.0, 4.5, 6.0 km/h). Six datasets at each velocity were collected from 16 men. A variability range VR throughout the gait cycle at each velocity for each joint angle for each person was calculated. The joint angles at each velocity were compared pairwise, and whenever this showed values within the VR of this velocity, the case was positive. By adding the positives throughout the gait cycle, phases with high and low concurrences were located; peak concurrence was observed at mid-stance phase. Striving for the same velocity for the suspect and perpetrator is recommended. © 2014 American Academy of Forensic Sciences.

  17. Smooth and Energy Saving Gait Planning for Humanoid Robot Using Geodesics

    Liandong Zhang

    2012-01-01

    Full Text Available A novel gait planning method using geodesics for humanoid robot is given in this paper. Both the linear inverted pendulum model and the exact Single Support Phase (SSP are studied in our energy optimal gait planning based on geodesics. The kinetic energy of a 2-dimension linear inverted pendulum is obtained at first. We regard the kinetic energy as the Riemannian metric and the geodesic on this metric is studied and this is the shortest line between two points on the Riemannian surface. This geodesic is the optimal kinetic energy gait for the COG because the kinetic energy along geodesic is invariant according to the geometric property of geodesics and the walking is smooth and energy saving. Then the walking in Single Support Phase is studied and the energy optimal gait for the swing leg is obtained using our geodesics method. Finally, experiments using state-of-the-art method and using our geodesics optimization method are carried out respectively and the corresponding currents of the joint motors are recorded. With the currents comparing results, the feasibility of this new gait planning method is verified.

  18. Phase dependence of transport-aperture coordination variability reveals control strategy of reach-to-grasp movements.

    Rand, Miya K; Shimansky, Y P; Hossain, Abul B M I; Stelmach, George E

    2010-11-01

    Based on an assumption of movement control optimality in reach-to-grasp movements, we have recently developed a mathematical model of transport-aperture coordination (TAC), according to which the hand-target distance is a function of hand velocity and acceleration, aperture magnitude, and aperture velocity and acceleration (Rand et al. in Exp Brain Res 188:263-274, 2008). Reach-to-grasp movements were performed by young adults under four different reaching speeds and two different transport distances. The residual error magnitude of fitting the above model to data across different trials and subjects was minimal for the aperture-closure phase, but relatively much greater for the aperture-opening phase, indicating considerable difference in TAC variability between those phases. This study's goal is to identify the main reasons for that difference and obtain insights into the control strategy of reach-to-grasp movements. TAC variability within the aperture-opening phase of a single trial was found minimal, indicating that TAC variability between trials was not due to execution noise, but rather a result of inter-trial and inter-subject variability of motor plan. At the same time, the dependence of the extent of trial-to-trial variability of TAC in that phase on the speed of hand transport was sharply inconsistent with the concept of speed-accuracy trade-off: the lower the speed, the larger the variability. Conversely, the dependence of the extent of TAC variability in the aperture-closure phase on hand transport speed was consistent with that concept. Taking into account recent evidence that the cost of neural information processing is substantial for movement planning, the dependence of TAC variability in the aperture-opening phase on task performance conditions suggests that it is not the movement time that the CNS saves in that phase, but the cost of neuro-computational resources and metabolic energy required for TAC regulation in that phase. Thus, the CNS

  19. Lunar phase-dependent expression of cryptochrome and a photoperiodic mechanism for lunar phase-recognition in a reef fish, goldlined spinefoot.

    Fukushiro, Masato; Takeuchi, Takahiro; Takeuchi, Yuki; Hur, Sung-Pyo; Sugama, Nozomi; Takemura, Akihiro; Kubo, Yoko; Okano, Keiko; Okano, Toshiyuki

    2011-01-01

    Lunar cycle-associated physiology has been found in a wide variety of organisms. Recent study has revealed that mRNA levels of Cryptochrome (Cry), one of the circadian clock genes, were significantly higher on a full moon night than on a new moon night in coral, implying the involvement of a photoreception system in the lunar-synchronized spawning. To better establish the generalities surrounding such a mechanism and explore the underlying molecular mechanism, we focused on the relationship between lunar phase, Cry gene expression, and the spawning behavior in a lunar-synchronized spawner, the goldlined spinefoot (Siganus guttatus), and we identified two kinds of Cry genes in this animal. Their mRNA levels showed lunar cycle-dependent expression in the medial part of the brain (mesencephalon and diencephalon) peaking at the first quarter moon. Since this lunar phase coincided with the reproductive phase of the goldlined spinefoot, Cry gene expression was considered a state variable in the lunar phase recognition system. Based on the expression profiles of SgCrys together with the moonlight's pattern of timing and duration during its nightly lunar cycle, we have further speculated on a model of lunar phase recognition for reproductive control in the goldlined spinefoot, which integrates both moonlight and circadian signals in a manner similar to photoperiodic response.

  20. Plantar Pressure During Gait in Pregnant Women.

    Bertuit, Jeanne; Leyh, Clara; Rooze, Marcel; Feipel, Véronique

    2016-11-01

    During pregnancy, physical and hormonal modifications occur. Morphologic alterations of the feet are found. These observations can induce alterations in plantar pressure. This study sought to investigate plantar pressures during gait in the last 4 months of pregnancy and in the postpartum period. A comparison with nulliparous women was conducted to investigate plantar pressure modifications during pregnancy. Fifty-eight women in the last 4 months of pregnancy, nine postpartum women, and 23 healthy nonpregnant women (control group) performed gait trials on an electronic walkway at preferred speeds. The results for the three groups were compared using analysis of variance. During pregnancy, peak pressure and contact area decreased for the forefoot and rearfoot. These parameters increased significantly for the midfoot. The gait strategy seemed to be lateralization of gait with an increased contact area of the lateral midfoot and both reduced pressure and a later peak time on the medial forefoot. In the postpartum group, footprint parameters were modified compared with the pregnant group, indicating a trend toward partial return to control values, although differences persisted between the postpartum and control groups. Pregnant women had altered plantar pressures during gait. These findings could define a specific pattern of gait footprints in late pregnancy because plantar pressures had characteristics that could maintain a stable and safe gait.

  1. The Combined Effects of Body Weight Support and Gait Speed on Gait Related Muscle Activity : A Comparison between Walking in the Lokomat Exoskeleton and Regular Treadmill Walking

    Van Kammen, Klaske; Boonstra, Annemarijke; Reinders-Messelink, Heleen; Otter, den Rob

    2014-01-01

    Background: For the development of specialized training protocols for robot assisted gait training, it is important to understand how the use of exoskeletons alters locomotor task demands, and how the nature and magnitude of these changes depend on training parameters. Therefore, the present study

  2. Restoration of ankle movements with the ActiGait implantable drop foot stimulator: a safe and reliable treatment option for permanent central leg palsy.

    Martin, Klaus Daniel; Polanski, Witold Henryk; Schulz, Anne-Kathrin; Jöbges, Michael; Hoff, Hansjoerg; Schackert, Gabriele; Pinzer, Thomas; Sobottka, Stephan B

    2016-01-01

    OBJECT The ActiGait drop foot stimulator is a promising technique for restoration of lost ankle function by an implantable hybrid stimulation system. It allows ankle dorsiflexion by active peroneal nerve stimulation during the swing phase of gait. In this paper the authors report the outcome of the first prospective study on a large number of patients with stroke-related drop foot. METHODS Twenty-seven patients who experienced a stroke and with persisting spastic leg paresis received an implantable ActiGait drop foot stimulator for restoration of ankle movement after successful surface test stimulation. After 3 to 5 weeks, the stimulator was activated, and gait speed, gait endurance, and activation time of the system were evaluated and compared with preoperative gait tests. In addition, patient satisfaction was assessed using a questionnaire. RESULTS Postoperative gait speed significantly improved from 33.9 seconds per 20 meters to 17.9 seconds per 20 meters (p < 0.0001), gait endurance from 196 meters in 6 minutes to 401 meters in 6 minutes (p < 0.0001), and activation time from 20.5 seconds to 10.6 seconds on average (p < 0.0001). In 2 patients with nerve injury, surgical repositioning of the electrode cuff became necessary. One patient showed a delayed wound healing, and in another patient the system had to be removed because of a wound infection. Marked improvement in mobility, social participation, and quality of life was confirmed by 89% to 96% of patients. CONCLUSIONS The ActiGait implantable drop foot stimulator improves gait speed, endurance, and quality of life in patients with stroke-related drop foot. Regarding gait speed, the ActiGait system appears to be advantageous compared with foot orthosis or surface stimulation devices. Randomized trials with more patients and longer observation periods are needed to prove the long-term benefit of this device.

  3. Gait variability: methods, modeling and meaning

    Hausdorff Jeffrey M

    2005-07-01

    Full Text Available Abstract The study of gait variability, the stride-to-stride fluctuations in walking, offers a complementary way of quantifying locomotion and its changes with aging and disease as well as a means of monitoring the effects of therapeutic interventions and rehabilitation. Previous work has suggested that measures of gait variability may be more closely related to falls, a serious consequence of many gait disorders, than are measures based on the mean values of other walking parameters. The Current JNER series presents nine reports on the results of recent investigations into gait variability. One novel method for collecting unconstrained, ambulatory data is reviewed, and a primer on analysis methods is presented along with a heuristic approach to summarizing variability measures. In addition, the first studies of gait variability in animal models of neurodegenerative disease are described, as is a mathematical model of human walking that characterizes certain complex (multifractal features of the motor control's pattern generator. Another investigation demonstrates that, whereas both healthy older controls and patients with a higher-level gait disorder walk more slowly in reduced lighting, only the latter's stride variability increases. Studies of the effects of dual tasks suggest that the regulation of the stride-to-stride fluctuations in stride width and stride time may be influenced by attention loading and may require cognitive input. Finally, a report of gait variability in over 500 subjects, probably the largest study of this kind, suggests how step width variability may relate to fall risk. Together, these studies provide new insights into the factors that regulate the stride-to-stride fluctuations in walking and pave the way for expanded research into the control of gait and the practical application of measures of gait variability in the clinical setting.

  4. Self-perceived gait stability modulates the effect of daily life gait quality on prospective falls in older adults

    Weijer, R H A; Hoozemans, M J M; van Dieën, J H; Pijnappels, M

    2018-01-01

    BACKGROUND: Quality of gait during daily life activities and perceived gait stability are both independent risk factors for future falls in older adults. RESEARCH QUESTION: We investigated whether perceived gait stability modulates the association between gait quality and falling in older adults.

  5. A Scaling Analysis of Frequency Dependent Energy Partition for Local and Regional Seismic Phases from Explosions

    2007-08-31

    explosions at the former Soviet Semipalatinsk test site (STS). Labeled stations are those for which high resolution digital data are available. 12 8...characteristics of regional phase observations from underground nuclear explosions at the former Soviet Semipalatinsk and Novaya Zemlya test sites , the...various regional phases observed from underground nuclear explosions at the former Soviet Semipalatinsk test site (STS). Labeled stations are those for

  6. Gait variability measurements in lumbar spinal stenosis patients: part B. Preoperative versus postoperative gait variability

    Papadakis, N C; Christakis, D G; Tzagarakis, G N; Chlouverakis, G I; Kampanis, N A; Stergiopoulos, K N; Katonis, P G

    2009-01-01

    The objective of this study was to assess the gait variability of lumbar spinal stenosis (LSS) patients and to evaluate its postoperative progression. The hypothesis was that LSS patients' preoperative gait variability in the frequency domain was higher than the corresponding postoperative. A tri-axial accelerometer sensor was used for the gait measurement and a spectral differential entropy algorithm was used to measure the gait variability. Twelve subjects with LSS were measured before and after surgery. Preoperative measurements were performed 2 days before surgery. Postoperative measurements were performed 6 and 12 months after surgery. Preoperative gait variability was higher than the corresponding postoperative. Also, in most cases, gait variability appeared to decrease throughout the year

  7. Temperature-dependent pitch and phase diagram for incommensurate XY spins in a slab geometry

    Collins, M.; Saslow, W.M.

    1996-01-01

    Strain-engineered Heisenberg antiferromagnets recently have been produced by controlling the layer thickness of MnSe/ZnTe superlattices. Neutron-scattering studies reveal a spiral that tends to untwist with increasing temperature. To simulate this system, we employ an XY model with nearest- and second-nearest neighbor antiferromagnetic interactions. The bulk mean-field phase diagram has four possible phases, for the full range of the exchange constants. Monte Carlo calculations are performed for a slab geometry, using an algorithm that allows the system to choose incommensurate boundary conditions. The phase diagram is constructed by monitoring the spiral pitch as a function of temperature for a range of exchange constants. For appropriate exchange constants, good agreement is obtained with experiment. From the mean-field phase diagram it appears that strain engineering an NaCl structure in a superlattice configuration might produce a type of spiral phase, and an associated antiferromagnetic-to-spiral phase transition. copyright 1996 The American Physical Society

  8. Relationships of Stroke Patients’ Gait Parameters with Fear of Falling

    Park, Jin; Yoo, Ingyu

    2014-01-01

    [Purpose] The purpose of this study was to assess the correlation of gait parameters with fear of falling in stroke survivors. [Subjects] In total, 12 patients with stroke participated. [Methods] The subjects performed on a Biodex Gait Trainer 2 for 5 min to evaluate characteristic gait parameters. The kinematic gait parameters measured were gait speed, step cycle, step length, and time on each foot (step symmetry). All the subjects also completed a fall anxiety survey. [Results] Correlations...

  9. A study of the angular momentum dependence of the phase shift for finite range and Coulomb potentials

    Valluri, S.R.; Romo, W.J.

    1989-01-01

    The dependence of the phase shift δ l (k) on the angular momentum l is investigated. An analytic expression for the derivative of the phase shift with respect to angular momentum is derived for a class of potentials that includes complex and real potentials. The potentials behave like the finite range potential for small r and like a Coulomb potential for large r. Specific examples like the square well, the pure point charge Coulomb and a combination of a square well and the Coulomb potential are analytically treated. Possible applications are briefly indicated. (orig.)

  10. Multilevel orthopedic surgery for crouch gait in cerebral palsy: An evaluation using functional mobility and energy cost

    Dhiren Ganjwala

    2011-01-01

    Full Text Available Background: The evidence for the effectiveness of orthopaedic surgery to correct crouch gait in cerebral diplegic is insufficient. The crouch gait is defined as walking with knee flexion and ankle dorsiflexion through out the stance phase. Severe crouch gait in patients with spastic diplegia causes excessive loading of the patellofemoral joint and may result in anterior knee pain, gait deterioration, and progressive loss of function. We retrospectively evaluated the effect of surgery on the mobility and energy consumption at one year or more with the help of validated scales and scores. Materials and Methods: 18 consecutive patients with mean age of 14.6 years with cerebral diplegia with crouched gait were operated for multilevel orthopaedic surgery. Decisions for surgery were made with the observations on gait analysis and physical examination. The surgical intervention consisted of lengthening of short muscle-tendon units, shortening of long muscles and correction of osseous deformities. The paired samples t test was used to compare values of physical examination findings, walking speed and physiological cost index. Two paired sample Wilcoxon signed rank test was used to compare functional walking scales. Results: After surgery, improvements in functional mobility, walking speed and physiological cost index were found. No patient was able to walk 500 meters before surgery while all were able to walk after surgery. The improvements that were noted at one year were maintained at two years. Conclusions: Multilevel orthopedic surgery for older children and adolescents with crouch gait is effective for improving function and independence.

  11. Composition dependence of phase transformation behavior and shape memory effect of Ti(Pt, Ir)

    Yamabe-Mitarai, Y.; Hara, T.; Kitashima, T.; Miura, S.; Hosoda, H.

    2013-01-01

    Highlights: ► The partial isothemal section at 1523 K was determined in Ti–Pt–Ir. ► The high-temperature shape memory effect of Ti(Pt, Ir) was investigated. ► The shape recovery ratio was 72% in Ti–10Pt–32Ir after deformation at 1123 K. ► Ir addition to TiPt is effective to improve shape memory effect of TiPt. -- Abstract: The phase transformation and high-temperature shape memory effect of Ti(Pt, Ir) were investigated. First, the Ti-rich phase boundary of Ti(Pt, Ir) was investigated by phase composition analysis by secondary electron microscopy (SEM) using an electron probe X-ray micro analyzer (EPMA), X-ray diffraction analysis and transmission electron microscopy (TEM). Then, the three alloys Ti–35Pt–10Ir, Ti–22Pt–22Ir, and Ti–10Pt–32Ir (at%) close to the phase boundary but in the single phase of Ti(Pt, Ir) were prepared by the arc melting method. The shape memory effect and crystal structure were investigated by compression loading–unloading tests and high-temperature X-ray diffraction analysis, respectively

  12. Geometric Phase of the Gyromotion for Charged Particles in a Time-dependent Magnetic Field

    Liu, Jian; Qin, Hong

    2011-01-01

    We study the dynamics of the gyrophase of a charged particle in a magnetic field which is uniform in space but changes slowly with time. As the magnetic field evolves slowly with time, the changing of the gyrophase is composed of two parts. The rst part is the dynamical phase, which is the time integral of the instantaneous gyrofrequency. The second part, called geometric gyrophase, is more interesting, and it is an example of the geometric phase which has found many important applications in different branches of physics. If the magnetic field returns to the initial value after a loop in the parameter space, then the geometric gyrophase equals the solid angle spanned by the loop in the parameter space. This classical geometric gyrophase is compared with the geometric phase (the Berry phase) of the spin wave function of an electron placed in the same adiabatically changing magnetic field. Even though gyromotion is not the classical counterpart of the quantum spin, the similarities between the geometric phases of the two cases nevertheless reveal the similar geometric nature of the different physics laws governing these two physics phenomena.

  13. Phase-dependence of elbow muscle coactivation in front crawl swimming.

    Lauer, Jessy; Figueiredo, Pedro; Vilas-Boas, João Paulo; Fernandes, Ricardo J; Rouard, Annie Hélène

    2013-08-01

    Propulsion in swimming is achieved by complex sculling movements with elbow quasi-fixed on the antero-posterior axis to transmit forces from the hand and the forearm to the body. The purpose of this study was to investigate how elbow muscle coactivation was influenced by the front crawl stroke phases. Ten international level male swimmers performed a 200-m front crawl race-pace bout. Sagittal views were digitized frame by frame to determine the stroke phases (aquatic elbow flexion and extension, aerial elbow flexion and extension). Surface electromyograms (EMG) of the right biceps brachii and triceps brachii were recorded and processed using the integrated EMG to calculate a coactivation index (CI) for each phase. A significant effect of the phases on the CI was revealed with highest levels of coactivation during the aquatic elbow flexion and the aerial elbow extension. Swimmers stabilize the elbow joint to overcome drag during the aquatic phase, and act as a brake at the end of the recovery to replace the arm for the next stroke. The CI can provide insight into the magnitude of mechanical constraints supported by a given joint, in particular during a complex movement. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Optical properties of polarization-dependent geometrical phase elements with partially polarized light

    Gorodetski, Y.; Biener, G.; Niv, A.; Kleiner, V.; Hasman, E.

    2005-01-01

    Full Text:The behavior of geometrical phase elements illuminated with partially polarized monochromatic beams is being theoretically as well as experimentally investigated. The element discussed in this paper is composed of wave plates with retardation and space-variant orientation angle. We found that a beam emerging from such an element comprises two polarization orders of right and left-handed circularly polarized states with conjugate geometrical phase modification. This phase equals twice the orientation angle of the space-variant wave plate comprising the element. Apart from the two polarization orders, the emerging beam coherence polarization matrix comprises a matrix termed as the vectorial interference matrix. This matrix contains the information concerning the correlation between the two orthogonal circularly polarized portions of the incident beam. In this paper we measure this correlation by a simple interference experiment. Furthermore, we found that the equivalent mutual intensity of the emerging beam is being modulated according to the geometrical phase induced by the element. Other interesting phenomena along propagation will be discussed theoretically and experimentally demonstrated. We demonstrate experimentally our analysis by using a spherical geometrical phase element, which is realized by use of space-variant sub wavelength grating and illuminated with a CO 2 laser radiation of 10.6μm wavelength

  15. [The use of a robot-assisted Gait Trainer GT1 in patients in the acute period of cerebral stroke: a pilot study].

    Skvortsova, V I; Ivanova, G E; Kovrazhkina, E A; Rumiantseva, N A; Staritsyn, A N; Suvorov, A Iu; Sogomonian, E K

    2008-01-01

    An aim of the study was to evaluate efficacy of using Gait Trainer GT1, a robot-assisted gait trainer with a system of body-weight support, for the rehabilitation of gait in patients in the acute period of cerebral stroke. A main group included 30 patients in the acute period of ischemic and hemorrhage stroke and a control group--20 age- and sex matched patients. Patients of both groups had daily kinesitherapy sessions with a rehabilitator. Patients of the main group had additional sessions on the Gait Trainer GT1 from the moment of functional readiness to adequate orthostatic probe. Efficacy of rehabilitation was assessed in the four following phases: the first verticalization of patient in the standing position, adaptation of patient to the standing position, walking with assistance, independent walking. Muscular power (scores) in all muscles of low extremities, muscle tonus (the Ashfort scale), amplitude of tendinous reflexes on the reflexes scale, sensory disturbances and discoordination syndromes (specially elaborated scales), pathological positions in the axial muscular system and extremities, functional status (a steadiness scale, the Berg balance scale, the Barthel scale, 5 m test) were assessed in each phase. Stabilometry was conducted for objective evaluation of vertical balance function. The duration of sessions on GT1 and a number of exercises were depended on the patient's tolerability to physical activity. Percentage of relief was determined by the ability of a patient to balance in the standing position. Each patient had 8-10 sessions. A significant improvement of the functional status: ability to balance in standing position, walking, increase of self-care skills were observed in both groups. No significant differences in the level of functional improvements were found compared to the control group. However some peculiarities of the rehabilitation of primary neurologic deficit were observed during CT1-trainings: the normalization of muscle tonus

  16. Balance and gait improved in patients with MS after physiotherapy based on the Bobath concept.

    Smedal, Tori; Lygren, Hildegunn; Myhr, Kjell-Morten; Moe-Nilssen, Rolf; Gjelsvik, Bente; Gjelsvik, Olav; Strand, Liv Inger; Inger, Liv

    2006-06-01

    Patients with multiple sclerosis (MS) tend to have movement difficulties, and the effect of physiotherapy for this group of patients has been subjected to limited systematic research. In the present study physiotherapy based on the Bobath concept, applied to MS patients with balance and gait problems, was evaluated. The ability of different functional tests to demonstrate change was evaluated. A single-subject experimental study design with ABAA phases was used, and two patients with relapsing-remitting MS in stable phase were treated. Tests were performed 12 times, three at each phase: A (at baseline); B (during treatment); A (immediately after treatment); and A (after two months). The key feature of treatment was facilitation of postural activity and selective control of movement. Several performance and self report measures and interviews were used. After intervention, improved balance was shown by the Berg Balance Scale (BBS) in both patients, and improved quality of gait was indicated by the Rivermead Visual Gait Assessment (RVGA). The patients also reported improved balance and gait function in the interviews and scored their condition as 'much improved'. Gait parameters, recorded by an electronic walkway, changed, but differently in the two patients. Among the physical performance tests the BBS and the RVGA demonstrated the highest change, while no or minimal change was demonstrated by the Rivermead Mobility Index (RMI) and Ratings of Perceived Exertion (RPE). The findings indicate that balance and gait can be improved after physiotherapy based on the Bobath concept, but this should be further evaluated in larger controlled trials of patients with MS.

  17. Correlation between static radiographic measurements and intersegmental angular measurements during gait using a multisegment foot model.

    Lee, Dong Yeon; Seo, Sang Gyo; Kim, Eo Jin; Kim, Sung Ju; Lee, Kyoung Min; Farber, Daniel C; Chung, Chin Youb; Choi, In Ho

    2015-01-01

    Radiographic examination is a widely used evaluation method in the orthopedic clinic. However, conventional radiography alone does not reflect the dynamic changes between foot and ankle segments during gait. Multiple 3-dimensional multisegment foot models (3D MFMs) have been introduced to evaluate intersegmental motion of the foot. In this study, we evaluated the correlation between static radiographic indices and intersegmental foot motion indices. One hundred twenty-five females were tested. Static radiographs of full-leg and anteroposterior (AP) and lateral foot views were performed. For hindfoot evaluation, we measured the AP tibiotalar angle (TiTA), talar tilt (TT), calcaneal pitch, lateral tibiocalcaneal angle, and lateral talcocalcaneal angle. For the midfoot segment, naviculocuboid overlap and talonavicular coverage angle were calculated. AP and lateral talo-first metatarsal angles and metatarsal stacking angle (MSA) were measured to assess the forefoot. Hallux valgus angle (HVA) and hallux interphalangeal angle were measured. In gait analysis by 3D MFM, intersegmental angle (ISA) measurements of each segment (hallux, forefoot, hindfoot, arch) were recorded. ISAs at midstance phase were most highly correlated with radiography. Significant correlations were observed between ISA measurements using MFM and static radiographic measurements in the same segment. In the hindfoot, coronal plane ISA was correlated with AP TiTA (P foot motion indices at midstance phase during gait measured by 3D MFM gait analysis were correlated with the conventional radiographic indices. The observed correlation between MFM measurements at midstance phase during gait and static radiographic measurements supports the fundamental basis for the use of MFM in analysis of dynamic motion of foot segment during gait. © The Author(s) 2014.

  18. Screw-Home Movement of the Tibiofemoral Joint during Normal Gait: Three-Dimensional Analysis.

    Kim, Ha Yong; Kim, Kap Jung; Yang, Dae Suk; Jeung, Sang Wook; Choi, Han Gyeol; Choy, Won Sik

    2015-09-01

    The purpose of this study was to evaluate the screw-home movement at the tibiofemoral joint during normal gait by utilizing the 3-dimensional motion capture technique. Fifteen young males and fifteen young females (total 60 knee joints) who had no history of musculoskeletal disease or a particular gait problem were included in this study. Two more markers were attached to the subject in addition to the Helen-Hayes marker set. Thus, two virtual planes, femoral coronal plane (P f ) and tibial coronal plane (P t ), were created by Skeletal Builder software. This study measured the 3-dimensional knee joint movement in the sagittal, coronal, and transverse planes of these two virtual planes (P f and P t ) during normal gait. With respect to kinematics and kinetics, both males and females showed normal adult gait patterns, and the mean difference in the temporal gait parameters was not statistically significant (p > 0.05). In the transverse plane, the screw-home movement occurred as expected during the pre-swing phase and the late-swing phase at an angle of about 17°. However, the tibia rotated externally with respect to the femur, rather than internally, while the knee joint started to flex during the loading response (paradoxical screw-home movement), and the angle was 6°. Paradoxical screw-home movement may be an important mechanism that provides stability to the knee joint during the remaining stance phase. Obtaining the kinematic values of the knee joint during gait can be useful in diagnosing and treating the pathological knee joints.

  19. Morphology and crystalline-phase-dependent electrical insulating properties in tailored polypropylene for HVDC cables

    Zha, Jun-Wei; Yan, Hong-Da; Li, Wei-Kang; Dang, Zhi-Min

    2016-11-01

    Polypropylene (PP) has become one promising material to potentially replace the cross-link polyethylene used for high voltage direct current cables. Besides the isotactic polypropylene, the block polypropylene (b-PP) and random polypropylene (r-PP) can be synthesized through the copolymerization of ethylene and propylene molecules. In this letter, the effect of morphology and crystalline phases on the insulating electrical properties of PP was investigated. It was found that the introduction of polyethylene monomer resulted in the formation of β and γ phases in b-PP and r-PP. The results from the characteristic trap energy levels indicated that the β and γ phases could induce deep electron traps which enable to capture the carriers. And the space charge accumulation was obviously suppressed. Besides, the decreased electrical conductivity was observed in b-PP and r-PP. It is attributed to the existence of deep traps which can effectively reduce the carrier mobility and density in materials.

  20. Radiation-induced p53 protein response in the A549 cell line is culture growth-phase dependent

    Johnson, N.F.; Gurule, D.M.; Carpenter, T.R.

    1995-12-01

    One role of the p53 tumor suppressor protein has been recently revealed. Kastan, M.B. reported that p53 protein accumulates in cells exposed to ionizing radiation. The accumulation of p53 protein is in response to DNA damage, most importantly double-strand breaks, that results from exposure to ionizing radiation. The rise in cellular p53 levels is necessary for an arrest in the G{sub 1} phase of the cell cycle to provide additional time for DNA repair. The p53 response has also been demonstrated to enhance PCNA-dependent repair. p53 is thus an important regulator of the cellular response to DNA-damaging radiation. From this data, it can be concluded that the magnitude of the p53 response is not dependent on the phase of culture growth.

  1. A robotic exoskeleton to treat crouch gait from cerebral palsy: Initial kinematic and neuromuscular evaluation.

    Lerner, Zachary F; Damiano, Diane L; Bulea, Thomas C

    2016-08-01

    A robotic exoskeleton was designed for individuals with crouch gait caused by cerebral palsy with the intent to supplement existing muscle function during walking. The aim of this study was to evaluate how powered knee extension assistance provided during stance and swing phases of the gait cycle affect knee kinematics, and knee flexor and extensor muscle activity. Muscle activity and kinematic data were collected from four individuals with crouch gait from cerebral palsy during their normal walking condition and while walking with the exoskeleton under stance, swing, and stance & swing assistance. The exoskeleton was effective in reducing crouch by an average of 13.8° in three of the four participants when assistance was provided during the stance phase; assistance during the swing phase alone was ineffective. Peak knee extensor activity was maintained for all of the conditions during the stance and swing phases. Integrated (i.e. area under the curve) knee extensor activity decreased in two of the subjects indicating a more well-modulated activation pattern. Modest increases in peak and integrated antagonist knee flexor activity were exhibited in all participants; the subject without kinematic improvement had the greatest increase. While the exoskeleton was well tolerated, additional training with a focus on reducing knee flexor activity may lead to further improvements in crouch gait reduction.

  2. Ultrasonic motion analysis system - measurement of temporal and spatial gait parameters

    Huitema, RB; Hof, AL; Postema, K

    The duration of stance and swing phase and step and stride length are important parameters in human gait. In this technical note a low-cost ultrasonic motion analysis system is described that is capable of measuring these temporal and spatial parameters while subjects walk on the floor. By using the

  3. The relationship between patellofemoral and tibiofemoral morphology and gait biomechanics following arthroscopic partial medial meniscectomy

    Dempsey, Alasdair R.; Wang, Yuanyuan; Thorlund, Jonas Bloch

    2013-01-01

    adduction moment, knee adduction moment impulse, 1st peak in the knee flexion moment, knee extension range of motion, and the heel strike transient from the vertical ground reaction force trace were identified from the gait data. Results Increased knee stance phase range of motion was associated...

  4. Phase-Angle Dependence of Determinations of Diameter, Albedo, and Taxonomy: A Case Study of NEO 3691 Bede

    Wooden, Diane H.; Lederer, Susan M.; Jehin, Emmanuel; Howell, Ellen S.; Fernandez, Yan; Harker, David E.; Ryan, Erin; Lovell, Amy; Woodward, Charles E.; Benner, Lance A.

    2015-01-01

    Parameters important for NEO risk assessment and mitigation include Near-Earth Object diameter and taxonomic classification, which translates to surface composition. Diameters of NEOs are derived from the thermal fluxes measured by WISE, NEOWISE, Spitzer Warm Mission and ground-based telescopes including the IRTF and UKIRT. Diameter and its coupled parameters Albedo and IR beaming parameter (a proxy for thermal inertia and/or surface roughness) are dependent upon the phase angle, which is the Sun-target-observer angle. Orbit geometries of NEOs, however, typically provide for observations at phase angles greater than 20 degrees. At higher phase angles, the observed thermal emission is sampling both the day and night sides of the NEO. We compare thermal models for NEOs that exclude (NEATM) and include (NESTM) night-side emission. We present a case study of NEO 3691 Bede, which is a higher albedo object, X (Ec) or Cgh taxonomy, to highlight the range of H magnitudes for this object (depending on the albedo and phase function slope parameter G), and to examine at different phase angles the taxonomy and thermal model fits for this NEO. Observations of 3691 Bede include our observations with IRTF+SpeX and with the 10 micrometer UKIRT+Michelle instrument, as well as WISE and Spitzer Warm mission data. By examining 3691 Bede as a case study, we highlight the interplay between the derivation of basic physical parameters and observing geometry, and we discuss the uncertainties in H magnitude, taxonomy assignment amongst the X-class (P, M, E), and diameter determinations. Systematic dependencies in the derivation of basic characterization parameters of H-magnitude, diameter, albedo and taxonomy with observing geometry are important to understand. These basic characterization parameters affect the statistical assessments of the NEO population, which in turn, affects the assignment of statistically-assessed basic parameters to discovered but yet-to-be-fully-characterized NEOs.

  5. Temperature dependence of the magnetic anisotropy of metallic Y-Ba-Cu-O single crystals in the normal phase

    Miljak, M.; Zlatic, V.; Kos, I.; Aviani, I.; Hamzic, A.; Collin, G.

    1990-01-01

    The magnetic anisotropy measurements of metallic Y-Ba-Cu-O compounds in the normal phase reveal a temperature-dependent diamagnetic component of the susceptibility that increases with decreasing temperature. The temperature variation of the susceptibility anisotropy and its total change do not seem to be much affected by the presence of the superconductivity at some lower temperature and could not be accounted for by superconducting fluctuations. Rather, the data remind one of the behavior of some quasi-two-dimensional metals with anisotropic Fermi surfaces, reflecting the properties of the low-energy excitations in the normal phase. The anisotropy measurements above the bulk superconducting transition temperature T c reveal the nonlinear effects, which are due to the onset of superconductivity in disconnected grains. The existence of a two-step transition, typical for granular superconductors, should be taken into consideration if the normal-phase susceptibility data are compared with the theoretical predictions in the vicinity of T c

  6. Quantitative Phase-Field Approach for Simulating Grain Growth in Anisotropic Systems with Arbitrary Inclination and Misorientation Dependence

    Moelans, N.; Blanpain, B.; Wollants, P.

    2008-01-01

    A phase-field approach for quantitative simulations of grain growth in anisotropic systems is introduced, together with a new methodology to derive appropriate model parameters that reproduce given misorientation and inclination dependent grain boundary energy and mobility in the simulations. The proposed model formulation and parameter choice guarantee a constant diffuse interface width and consequently give high controllability of the accuracy in grain growth simulations

  7. Clastogenic adaption of Vicia faba root tip meristem cells after consecutive treatments with S-phase dependent and S-phase independent agents

    Heindorff, K.; Schubert, I.; Rieger, R.; Michaelis, A.

    1987-01-01

    Pretreatment of Vicia faba root tip meristems with low doses of S-phase independent clastogens, such as X-rays or bleomycin, prior to a high (challenge) dose of S-phase dependent clastogens, such as alkylating agents (TEM, Trenimon) or the pyridazine derivative MH, led to decreased challenge treatment-induced aberration frequencies, i.e., clastogenic adaptation. Using the inverse treatment sequence bleomycin and MH proved to be able to substitute for each other in provoking clastogenic (cross) adaptation while bleomycin and alkylating agents were unable to do so. The data support the assumption of inducible cellular functions that become triggered by low clastogen doses and additionally describe some particular properties of bleomycin when used for conditioning. Bleomycin proved to be capable to exert protection independent of the agent used for challenge treatment. (author)

  8. Phase-dependent absorption features in X-ray spectra of X-ray Dim Isolated Neutron Stars

    Borghese, A.; Rea, N.; Coti Zelati, F.; Turolla, R.; Tiengo, A.; Zane, S.

    2017-12-01

    A detailed phase-resolved spectroscopy of archival XMM-Newton observations of X-ray Dim Isolated Neutron Stars (XDINSs) led to the discovery of narrow and strongly phase-dependent absorption features in two of these sources. The first was discovered in the X-ray spectrum of RX J0720.4-3125, followed by a new possible candidate in RX J1308.6+2127. Both spectral lines have similar properties: they are detected for only ˜ 20% of the rotational cycle and appear to be stable over the timespan covered by the observations. We performed Monte Carlo simulations to test the significance of these phase-variable features and in both cases the outcome has confirmed the detection with a confidence level > 4.6σ. Because of the narrow width and the strong dependence on the pulsar rotational phase, the most likely interpretation for these spectral features is in terms of resonant proton cyclotron absorption scattering in a confined high-B structure close to the stellar surface. Within the framework of this interpretation, our results provide evidence for deviations from a pure dipole magnetic field on small scales for highly magnetized neutron stars and support the proposed scenario of XDINSs being aged magnetars, with a strong non-dipolar crustal B-field component.

  9. Composition-dependent properties and phase stability of Fe-Pd ferromagnetic shape memory alloys: A first-principles study

    Li, Chun-Mei; Hu, Yan-Fei

    2017-12-01

    The composition-dependent properties and their correlation with the phase stability of Fe75+xPd25-x (- 10.0 ≤x ≤10.0 ) alloys are systematically investigated by using first-principles exact muffin-tin orbitals (EMTO)-coherent potential approximation (CPA) calculations. It is shown that the martensitic transformation (MT) from L 12 to body-centered-tetragonal (bct) occurs in the ordered alloys with about -5.0 ≤x ≤10.0 . In both the L 12 and bct phases, the evaluated a and c/a agree well with the available experimental data; the average magnetic moment per atom increases whereas the local magnetic moments of Fe atoms, dependent on both their positions and the structure of the alloy, decrease with increasing x. The tetragonal shear elastic constant of the L 12 phase ( C ' ) decreases whereas that of the bct phase (Cs) increases with x. The tetragonality of the martensite ( |1 -c /a | ) increases whereas its energy relative to the austenite with a negative value decreases with Fe addition. All these effects account for the increase of MT temperature (TM) with x. The MT from L 12 to bct is finally confirmed originating from the splitting of Fe 3d Eg and T2 g bands upon tetragonal distortion due to the Jahn-Teller effect.

  10. Restoration of gait for spinal cord injury patients using HAL with intention estimator for preferable swing speed.

    Tsukahara, Atsushi; Hasegawa, Yasuhisa; Eguchi, Kiyoshi; Sankai, Yoshiyuki

    2015-03-01

    This paper proposes a novel gait intention estimator for an exoskeleton-wearer who needs gait support owing to walking impairment. The gait intention estimator not only detects the intention related to the start of the swing leg based on the behavior of the center of ground reaction force (CoGRF), but also infers the swing speed depending on the walking velocity. The preliminary experiments categorized into two stages were performed on a mannequin equipped with the exoskeleton robot [Hybrid Assistive Limb: (HAL)] including the proposed estimator. The first experiment verified that the gait support system allowed the mannequin to walk properly and safely. In the second experiment, we confirmed the differences in gait characteristics attributed to the presence or absence of the proposed swing speed profile. As a feasibility study, we evaluated the walking capability of a severe spinal cord injury patient supported by the system during a 10-m walk test. The results showed that the system enabled the patient to accomplish a symmetrical walk from both spatial and temporal standpoints while adjusting the speed of the swing leg. Furthermore, the critical differences of gait between our system and a knee-ankle-foot orthosis were obtained from the CoGRF distribution and the walking time. Through the tests, we demonstrated the effectiveness and practical feasibility of the gait support algorithms.

  11. Polarity-dependent reversible resistance switching in Ge-Sb-Te phase-change thin films

    Pandian, Ramanathaswamy; Kooi, Bart J.; Palasantzas, George; De Hosson, Jeff T. M.; Pauza, Andrew

    2007-01-01

    In this paper, we demonstrate reversible resistance switching in a capacitorlike cell using a Ge-Sb-Te film that does not rely on amorphous-crystalline phase change. The polarity of the applied electric field switches the cell resistance between lower- and higher-resistance states, as was observed

  12. Composition Dependence of Water Permeation Across Multicomponent Gel-Phase Bilayers

    Hartkamp, R.M.; Moore, Timothy C.; Iacovella, Christopher R.; Thompson, Michael A.; Bulsara, Pallav A.; Moore, David J.; McCabe, Clare

    2018-01-01

    The permeability of multicomponent phospholipid bilayers in the gel phase is investigated via molecular dynamics simulation. The physical role of the different molecules is probed by comparing multiple mixed-component bilayers containing distearylphosphatidylcholine (DSPC) with varying amounts of

  13. Detecting Gait Asymmetry with Wearable Accelerometers

    2015-03-18

    by overuse. Common overuse injuries include stress fractures , tendinitis, bursitis, fasciitis, and medial tibial stress syndrome (shin splints) [11...magnitude feature values for subject 1 are shown in (a), before and after repetitive stress injury. Magnitude and pattern features are plotted in...Dudziñski, A. Lees, M. Lake, and M. Wychowañski, “Adjustments in gait symmetry with walking speed in trans-femoral and trans- tibial amputees,” Gait

  14. Kinematic gait analyses in healthy Golden Retrievers

    Silva, Gabriela C.A.; Cardoso, Mariana Trés; Gaiad, Thais P.; Brolio, Marina P.; Oliveira, Vanessa C.; Assis Neto, Antonio; Martins, Daniele S.; Ambrósio, Carlos E.

    2014-01-01

    Kinematic analysis relates to the relative movement between rigid bodies and finds application in gait analysis and other body movements, interpretation of their data when there is change, determines the choice of treatment to be instituted. The objective of this study was to standardize the march of Dog Golden Retriever Healthy to assist in the diagnosis and treatment of musculoskeletal disorders. We used a kinematic analysis system to analyse the gait of seven dogs Golden Retriever, female,...

  15. Gait Disorders In Patients After Polytrauma

    Jakušonoka Ruta

    2015-04-01

    Full Text Available Evaluation of the gait of patients after polytrauma is important, as it indicates the ability of patients to the previous activities and work. The aim of our study was to evaluate the gait of patients with lower limb injuries in the medium-term after polytrauma. Three-dimensional instrumental gait analysis was performed in 26 polytrauma patients (16 women and 10 men; mean age 38.6 years, 14 to 41 months after the trauma. Spatio-temporal parameters, motions in pelvis and lower extremities joints in sagittal plane and vertical load ground reaction force were analysed. Gait parameters in polytrauma patients were compared with a healthy control group. Polytrauma patients in the injured side had decreased step length, cadence, hip extension, maximum knee flexion, vertical load ground reaction force, and increased stance time and pelvic anterior tilt; in the uninjured side they had decreased step length, cadence, maximum knee flexion, vertical load ground reaction force and increased stance time (p < 0.05. The use of the three-dimensional instrumental gait analysis in the evaluation of polytrauma patients with lower limb injuries consequences makes it possible to identify the gait disorders not only in the injured, but also in the uninjured side.

  16. Gait Recognition Using Wearable Motion Recording Sensors

    Davrondzhon Gafurov

    2009-01-01

    Full Text Available This paper presents an alternative approach, where gait is collected by the sensors attached to the person's body. Such wearable sensors record motion (e.g. acceleration of the body parts during walking. The recorded motion signals are then investigated for person recognition purposes. We analyzed acceleration signals from the foot, hip, pocket and arm. Applying various methods, the best EER obtained for foot-, pocket-, arm- and hip- based user authentication were 5%, 7%, 10% and 13%, respectively. Furthermore, we present the results of our analysis on security assessment of gait. Studying gait-based user authentication (in case of hip motion under three attack scenarios, we revealed that a minimal effort mimicking does not help to improve the acceptance chances of impostors. However, impostors who know their closest person in the database or the genders of the users can be a threat to gait-based authentication. We also provide some new insights toward the uniqueness of gait in case of foot motion. In particular, we revealed the following: a sideway motion of the foot provides the most discrimination, compared to an up-down or forward-backward directions; and different segments of the gait cycle provide different level of discrimination.

  17. Altered vision destabilizes gait in older persons.

    Helbostad, Jorunn L; Vereijken, Beatrix; Hesseberg, Karin; Sletvold, Olav

    2009-08-01

    This study assessed the effects of dim light and four experimentally induced changes in vision on gait speed and footfall and trunk parameters in older persons walking on level ground. Using a quasi-experimental design, gait characteristics were assessed in full light, dim light, and in dim light combined with manipulations resulting in reduced depth vision, double vision, blurred vision, and tunnel vision, respectively. A convenience sample of 24 home-dwelling older women and men (mean age 78.5 years, SD 3.4) with normal vision for their age and able to walk at least 10 m without assistance participated. Outcome measures were gait speed and spatial and temporal parameters of footfall and trunk acceleration, derived from an electronic gait mat and accelerometers. Dim light alone had no effect. Vision manipulations combined with dim light had effect on most footfall parameters but few trunk parameters. The largest effects were found regarding double and tunnel vision. Men increased and women decreased gait speed following manipulations (p=0.017), with gender differences also in stride velocity variability (p=0.017) and inter-stride medio-lateral trunk acceleration variability (p=0.014). Gender effects were related to differences in body height and physical functioning. Results indicate that visual problems lead to a more cautious and unstable gait pattern even under relatively simple conditions. This points to the importance of assessing vision in older persons and correcting visual impairments where possible.

  18. Humidity-dependent phase state of SOA particles from biogenic and anthropogenic precursors

    E. Saukko

    2012-08-01

    Full Text Available The physical phase state (solid, semi-solid, or liquid of secondary organic aerosol (SOA particles has important implications for a number of atmospheric processes. We report the phase state of SOA particles spanning a wide range of oxygen to carbon ratios (O / C, used here as a surrogate for SOA oxidation level, produced in a flow tube reactor by photo-oxidation of various atmospherically relevant surrogate anthropogenic and biogenic volatile organic compounds (VOCs. The phase state of laboratory-generated SOA was determined by the particle bounce behavior after inertial impaction on a polished steel substrate. The measured bounce fraction was evaluated as a function of relative humidity and SOA oxidation level (O / C measured by an Aerodyne high resolution time of flight aerosol mass spectrometer (HR-ToF AMS.

    The main findings of the study are: (1 biogenic and anthropogenic SOA particles are found to be amorphous solid or semi-solid based on the measured bounced fraction (BF, which was typically higher than 0.6 on a 0 to 1 scale. A decrease in the BF is observed for most systems after the SOA is exposed to relative humidity of at least 80% RH, corresponding to a RH at impaction of 55%. (2 Long-chain alkanes have a low BF (indicating a "liquid-like", less viscous phase particles at low oxidation levels (BF < 0.2 ± 0.05 for O / C = 0.1. However, BF increases substantially upon increasing oxidation. (3 Increasing the concentration of sulphuric acid (H2SO4 in solid SOA particles (here tested for longifolene SOA causes a decrease in BF levels. (4 In the majority of cases the bounce behavior of the various SOA systems did not show correlation with the particle O / C. Rather, the molar mass of the gas-phase VOC precursor showed a positive correlation with the resistance to the RH-induced phase change of the formed SOA particles.

  19. Development of a novel virtual reality gait intervention.

    Boone, Anna E; Foreman, Matthew H; Engsberg, Jack R

    2017-02-01

    Improving gait speed and kinematics can be a time consuming and tiresome process. We hypothesize that incorporating virtual reality videogame play into variable improvement goals will improve levels of enjoyment and motivation and lead to improved gait performance. To develop a feasible, engaging, VR gait intervention for improving gait variables. Completing this investigation involved four steps: 1) identify gait variables that could be manipulated to improve gait speed and kinematics using the Microsoft Kinect and free software, 2) identify free internet videogames that could successfully manipulate the chosen gait variables, 3) experimentally evaluate the ability of the videogames and software to manipulate the gait variables, and 4) evaluate the enjoyment and motivation from a small sample of persons without disability. The Kinect sensor was able to detect stride length, cadence, and joint angles. FAAST software was able to identify predetermined gait variable thresholds and use the thresholds to play free online videogames. Videogames that involved continuous pressing of a keyboard key were found to be most appropriate for manipulating the gait variables. Five participants without disability evaluated the effectiveness for modifying the gait variables and enjoyment and motivation during play. Participants were able to modify gait variables to permit successful videogame play. Motivation and enjoyment were high. A clinically feasible and engaging virtual intervention for improving gait speed and kinematics has been developed and initially tested. It may provide an engaging avenue for achieving thousands of repetitions necessary for neural plastic changes and improved gait. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Gait parameters in patients with diabetes mellitus DOI:10.5007/1980-0037.2010v12n2p155

    Cristina Elena Prado Teles Fregonesi

    2010-07-01

    Full Text Available Diabetes mellitus is a chronic disease that results in sensorimotor alterations. These changes affect balance and walking and predispose affected patients to falls. The aim of this review was to identify studies in the recent literature that assess gait parameters and aspects involved in walking. The MEDLINE, SciELO, LILACS and PEDro databases were searched using the following combination of keywords: diabetic neuropathies x gait; diabetes mellitus x gait, and diabetic foot x gait. After the application of selection criteria, 15 articles were retrieved, summarized, discussed, and are included in this review. Diabetic neuropathy was found to lead to deficits in step amplitude, gait velocity and gait cadence on flat surfaces, without sudden changes in direction or stops, and to balance and coordination deficits on inclined and uneven terrain. Diabetic neuropathies also increase plantar pressure rates and lead to difficulties in the terminal stance phase and pre-swing phase due to changes in triceps surae activation. Thus, the next initial contact occurs in an inadequate manner, with the forefoot and without absorption of shocks.

  1. Effects of noxious stimulation to the back or calf muscles on gait stability.

    van den Hoorn, Wolbert; Hug, François; Hodges, Paul W; Bruijn, Sjoerd M; van Dieën, Jaap H

    2015-11-26

    Gait stability is the ability to deal with small perturbations that naturally occur during walking. Changes in motor control caused by pain could affect this ability. This study investigated whether nociceptive stimulation (hypertonic saline injection) in a low back (LBP) or calf (CalfP) muscle affects gait stability. Sixteen participants walked on a treadmill at 0.94ms(-1) and 1.67ms(-1), while thorax kinematics were recorded using 3D-motion capture. From 110 strides, stability (local divergence exponent, LDE), stride-to-stride variability and root mean squares (RMS) of thorax linear velocities were calculated along the three movement axes. At 0.94ms(-1), independent of movement axes, gait stability was lower (higher LDE) and stride-to-stride variability was higher, during LBP and CalfP than no pain. This was more pronounced during CalfP, likely explained by the biomechanical function of calf muscles in gait, as supported by greater mediolateral RMS and stance time asymmetry than in LBP and no pain. At 1.67ms(-1), independent of movement axes, gait stability was greater and stride-to-stride variability was smaller with LBP than no pain and CalfP, whereas CalfP was not different from no pain. Opposite effects of LBP on gait stability between speeds suggests a more protective strategy at the faster speed. Although mediolateral RMS was greater and participants had more asymmetric stance times with CalfP than LBP and no pain, limited effect of CalfP at the faster speed could relate to greater kinematic constraints and smaller effects of calf muscle activity on propulsion at this speed. In conclusion, pain effects on gait stability depend on pain location and walking speed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Disorders of balance and gait in essential tremor are associated with midline tremor and age.

    Hoskovcová, Martina; Ulmanová, Olga; Sprdlík, Otakar; Sieger, Tomáš; Nováková, Jana; Jech, Robert; Růžička, Evžen

    2013-02-01

    Disorders of balance and gait have been observed in patients with essential tremor (ET), but their association with tremor severity remains unclear. This study aimed to evaluate postural instability and gait changes in ET patients and to investigate their relationship to tremor characteristics with regard to cerebellar dysfunction as a possible common pathogenetic mechanism in ET. Thirty ET patients (8F, mean (SD) age 55.8 (17.8), range 19-81 years) and 25 normal controls (7F, 53.0 (17.7), 19-81) were tested with the scales of Activities-specific Balance Confidence (ABC), Fullerton Advanced Balance (FAB), and International Cooperative Ataxia Rating Scale (ICARS). Posturography and gait were assessed using a Footscan® system. Tremor was evaluated by the Fahn-Tolosa-Marin Tremor Rating Scale (TRS) and accelerometry in five upper limb positions. A mean (SD) TRS sum score of 27.0 (13.2) corresponded to mild to moderate tremor severity in most patients. In comparison with controls, ET subjects exhibited lower tandem gait velocity (0.21 vs. 0.26 m/s, P = 0.028), more missteps (0.57 vs. 0.12, P = 0.039), and increased postural sway in tandem stance (sway area 301.1 vs. 202.9 mm(2), P = 0.045). In normal gait, step width increased with the midline tremor subscore of TRS (Pearson r = 0.60, P = 0.046). Moreover, significant correlations were found between age and quantitative measures of normal and tandem gait in ET patients but not in controls. ABC, FAB, and ICARS scores did not significantly differ between patients and controls. In conclusion, gait and balance alterations in ET patients occur even without subjective complaints. Their relationship with midline tremor and dependence on age suggest a connection with cerebellar dysfunction.

  3. [Modern approach to gait restoration in patients in the acute period of cerebral stroke].

    Skvortsova, V I; Ivanova, G E; Rumiantseva, N A; Staritsyn, A N; Kovrazhkina, E A; Suvorov, A Iu

    2010-01-01

    An objective of the study was to work out a complex program of gait restoration in patients with stroke using robot-driven mechanized gait trainers. The study included patients in the acute period of stroke (the mean age 59+/-10,4 years) who were not able to walk without assistance; 53 patients of the main group and 25 patients of the control group. The mean interval from the disease onset to the beginning of gait retraining sessions with mechanized gait trainers was 14+/-1,6 days depending on the adequacy of functional probes. The restoration program included everyday 30 minute sessions of exercise therapy. Patients of the main group received 20 min sessions using mechanized gait trainers Motomed Viva 2 and Gait Trainer 1 (GT1) with continuous monitoring of blood pressure and cardiac beat frequency. The number of sessions with GT1 was from 5 to 12, mean 7+/-1 sessions. After the complex restoration treatment, significant positive changes on scales of standing balance, functional categories of gait, Berg, Barthel (p< or =0.01) were observed in patients of the main group compared to controls. All patients of the main group became able to walk with a support or independently. The significant decrease (p< or =0.05) of a number of patients with disorders of proprioceptive sensitivity (from 37,7 to 9,4%) and with ataxia of the low extremities (from 37 to 11,3%) was observed in the main group, while no changes were seen in the control group. It has been concluded that the complex use of reflex kinesitherapy and robot-driven mechanotherapy in patients in the acute period of stroke allows to increase the functional activity and the level of self-service already prior to the discharge from hospital.

  4. Changes in gait patterns induced by rhythmic auditory stimulation for adolescents with acquired brain injury.

    Kim, Soo Ji; Shin, Yoon-Kyum; Yoo, Ga Eul; Chong, Hyun Ju; Cho, Sung-Rae

    2016-12-01

    The effects of rhythmic auditory stimulation (RAS) on gait in adolescents with acquired brain injury (ABI) were investigated. A total of 14 adolescents with ABI were initially recruited, and 12 were included in the final analysis (n = 6 each). They were randomly assigned to the experimental (RAS) or the control (conventional gait training) groups. The experimental group received gait training with RAS three times a week for 4 weeks. For both groups, spatiotemporal parameters and kinematic data, such as dynamic motions of joints on three-dimensional planes during a gait cycle and the range of motion in each joint, were collected. Significant group differences in pre-post changes were observed in cadence, walking velocity, and step time, indicating that there were greater improvements in those parameters in the RAS group compared with the control group. Significant increases in hip and knee motions in the sagittal plane were also observed in the RAS group. The changes in kinematic data significantly differed between groups, particularly from terminal stance to mid-swing phase. An increase of both spatiotemporal parameters and corresponding kinematic changes of hip and knee joints after RAS protocol indicates that the use of rhythmic cueing may change gait patterns in adolescents with ABI. © 2016 The Authors. Annals of the New York Academy of Sciences published by Wiley Periodicals, Inc. on behalf of New York Academy of Sciences.

  5. An accelerometry-based comparison of 2 robotic assistive devices for treadmill training of gait.

    Regnaux, Jean-Philippe; Saremi, Kaveh; Marehbian, Jon; Bussel, Bernard; Dobkin, Bruce H

    2008-01-01

    Two commercial robotic devices, the Gait Trainer (GT) and the Lokomat (LOKO), assist task-oriented practice of walking. The gait patterns induced by these motor-driven devices have not been characterized and compared. A healthy participant chose the most comfortable gait pattern on each device and for treadmill (TM) walking at 1, 2 (maximum for the GT), and 3 km/h and over ground at similar speeds. A system of accelerometers on the thighs and feet allowed the calculation of spatiotemporal features and accelerations during the gait cycle. At the 1 and 2 km/h speed settings, single-limb stance times were prolonged on the devices compared with overground walking. Differences on the LOKO were decreased by adjusting the hip and knee angles and step length. At the 3 km/h setting, the LOKO approximated the participant's overground parameters. Irregular accelerations and decelerations from toe-off to heel contact were induced by the devices, especially at slower speeds. The LOKO and GT impose mechanical constraints that may alter leg accelerations-decelerations during stance and swing phases, as well as stance duration, especially at their slower speed settings, that are not found during TM and overground walking. The potential impact of these perturbations on training to improve gait needs further study.

  6. Gait training reduces ankle joint stiffness and facilitates heel strike in children with Cerebral Palsy.

    Willerslev-Olsen, Maria; Lorentzen, Jakob; Nielsen, Jens Bo

    2014-01-01

    Foot drop and toe walking are frequent concerns in children with cerebral palsy (CP). Increased stiffness of the ankle joint muscles may contribute to these problems. Does four weeks of daily home based treadmill training with incline reduce ankle joint stiffness and facilitate heel strike in children with CP? Seventeen children with CP (4-14 years) were recruited. Muscle stiffness and gait ability were measured twice before and twice after training with an interval of one month. Passive and reflex-mediated stiffness were measured by a dynamometer which applied stretches below and above reflex threshold. Gait kinematics were recorded by 3-D video-analysis during treadmill walking. Foot pressure was measured by force-sensitive foot soles during treadmill and over-ground walking. Children with increased passive stiffness showed a significant reduction in stiffness following training (P = 0.01). Toe lift in the swing phase (P = 0.014) and heel impact (P = 0.003) increased significantly following the training during both treadmill and over-ground walking. Daily intensive gait training may influence the elastic properties of ankle joint muscles and facilitate toe lift and heel strike in children with CP. Intensive gait training may be beneficial in preventing contractures and maintain gait ability in children with CP.

  7. Comparison of trunk activity during gait initiation and walking in humans.

    Jean-Charles Ceccato

    Full Text Available To understand the role of trunk muscles in maintenance of dynamic postural equilibrium we investigate trunk movements during gait initiation and walking, performing trunk kinematics analysis, Erector spinae muscle (ES recordings and dynamic analysis. ES muscle expressed a metachronal descending pattern of activity during walking and gait initiation. In the frontal and horizontal planes, lateroflexion and rotation occur before in the upper trunk and after in the lower trunk. Comparison of ES muscle EMGs and trunk kinematics showed that trunk muscle activity precedes corresponding kinematics activity, indicating that the ES drive trunk movement during locomotion and thereby allowing a better pelvis mobilization. EMG data showed that ES activity anticipates propulsive phases in walking with a repetitive pattern, suggesting a programmed control by a central pattern generator. Our findings also suggest that the programs for gait initiation and walking overlap with the latter beginning before the first has ended.

  8. Research the Gait Characteristics of Human Walking Based on a Robot Model and Experiment

    He, H. J.; Zhang, D. N.; Yin, Z. W.; Shi, J. H.

    2017-02-01

    In order to research the gait characteristics of human walking in different walking ways, a robot model with a single degree of freedom is put up in this paper. The system control models of the robot are established through Matlab/Simulink toolbox. The gait characteristics of straight, uphill, turning, up the stairs, down the stairs up and down areanalyzed by the system control models. To verify the correctness of the theoretical analysis, an experiment was carried out. The comparison between theoretical results and experimental results shows that theoretical results are better agreement with the experimental ones. Analyze the reasons leading to amplitude error and phase error and give the improved methods. The robot model and experimental ways can provide foundation to further research the various gait characteristics of the exoskeleton robot.

  9. Carrier-envelope phase-dependent transmitted spectra in inversion-asymmetric media with permanent dipole moments

    Yang Weifeng; Song Xiaohong; Zhang Chaojin; Xu Zhizhan

    2009-01-01

    We investigate the transmitted spectra of a few-cycle ultrashort pulse in an inversion-asymmetric medium with a permanent dipole moment (PDM). Our results show that even-order harmonics can be generated in this medium. Moreover, the generated even-order harmonics depend strongly on the carrier-envelope phase (CEP) of initial incident few-cycle ultrashort pulses. Physical analysis of the re-emitted spectra of the medium reveals that the CEP-dependent spectral effect is originated from the inversion-asymmetric structure and the corresponding PDM effects: two-photon transition dominates in the nonlinear process and further induces the generations of the even-order harmonics. Furthermore, the orientation relation between the electric field peak of the pulse and the PDM results in even-order harmonic generations depending on the CEP.

  10. TEMPERATURE DEPENDENT PHASE BEHAVIOR AND PROTEIN PARTITIONING IN GIANT PLASMA MEMBRANE VESICLES

    Johnson, SA; Stinson, BM; Go, M; Carmona, LM; Reminick, JI; Fang, X; Baumgart, T

    2010-01-01

    Liquid-ordered (Lo) and liquid-disordered (Ld) phase coexistence has been suggested to partition the plasma membrane of biological cells into lateral compartments, allowing for enrichment or depletion of functionally relevant molecules. This dynamic partitioning might be involved in fine-tuning cellular signaling fidelity through coupling to the plasma membrane protein and lipid composition. In earlier work, giant plasma membrane vesicles, obtained by chemically induced blebbing from cultured...

  11. Internal Models Support Specific Gaits in Orthotic Devices

    Matthias Braun, Jan; Wörgötter, Florentin; Manoonpong, Poramate

    2014-01-01

    Patients use orthoses and prosthesis for the lower limbs to support and enable movements, they can not or only with difficulties perform themselves. Because traditional devices support only a limited set of movements, patients are restricted in their mobility. A possible approach to overcome such...... the system's accuracy and robustness on a Knee-Ankle-Foot-Orthosis, introducing behaviour changes depending on the patient's current walking situation. We conclude that the here presented model-based support of different gaits has the power to enhance the patient's mobility....

  12. Free-living gait characteristics in ageing and Parkinson's disease: impact of environment and ambulatory bout length.

    Del Din, Silvia; Godfrey, Alan; Galna, Brook; Lord, Sue; Rochester, Lynn

    2016-05-12

    Gait is emerging as a powerful diagnostic and prognostic tool, and as a surrogate marker of disease progression for Parkinson's disease (PD). Accelerometer-based body worn monitors (BWMs) facilitate the measurement of gait in clinical environments. Moreover they have the potential to provide a more accurate reflection of gait in the home during habitual behaviours. Emerging research suggests that measurement of gait using BWMs is feasible but this has not been investigated in depth. The aims of this study were to explore (i) the impact of environment and (ii) ambulatory bout (AB) length on gait characteristics for discriminating between people with PD and age-matched controls. Fourteen clinically relevant gait characteristics organised in five domains (pace, variability, rhythm, asymmetry, postural control) were quantified using laboratory based and free-living data collected over 7 days using a BWM placed on the lower back in 47 PD participants and 50 controls. Free-living data showed that both groups walked with decreased pace and increased variability, rhythm and asymmetry compared to walking in the laboratory setting. Four of the 14 gait characteristics measured in free-living conditions were significantly different between controls and people with PD compared to two measured in the laboratory. Between group differences depended on bout length and were more apparent during longer ABs. ABs ≤ 10s did not discriminate between groups. Medium to long ABs highlighted between-group significant differences for pace, rhythm and asymmetry. Longer ABs should therefore be taken into account when evaluating gait characteristics in free-living conditions. This study provides encouraging results to support the use of a single BWM for free-living gait evaluation in people with PD with potential for research and clinical application.

  13. Flight Extraction and Phase Identification for Large Automatic Dependent Surveillance–Broadcast Datasets

    Sun, J.; Ellerbroek, J.; Hoekstra, J.M.

    2017-01-01

    AUTOMATIC dependent surveillance–broadcast (ADS-B) [1,2] is widely implemented in modern commercial aircraft and will become mandatory equipment in 2020. Flight state information such as position, velocity, and vertical rate are broadcast by tens of thousands of aircraft around the world constantly

  14. LOPES: Selective control of gait functions during the gait rehabilitation of CVA patients

    Ekkelenkamp, R.; Veneman, J.F.; van der Kooij, Herman

    2005-01-01

    LOPES aims for an active role of the patient by selective and partial support of gait functions during robotic treadmill training sessions. Virtual model control (VMC) was applied to the robot as an intuitive method for translating current treadmill gait rehabilitation therapy programs into robotic

  15. Is Freezing of Gait in Parkinson's Disease a Result of Multiple Gait Impairments? Implications for Treatment

    Plotnik, Meir; Giladi, Nir; Hausdorff, Jeffrey M.

    2012-01-01

    Several gait impairments have been associated with freezing of gait (FOG) in patients with Parkinson's disease (PD). These include deteriorations in rhythm control, gait symmetry, bilateral coordination of gait, dynamic postural control and step scaling. We suggest that these seemingly independent gait features may have mutual interactions which, during certain circumstances, jointly drive the predisposed locomotion system into a FOG episode. This new theoretical framework is illustrated by the evaluation of the potential relationships between the so-called “sequence effect”, that is, impairments in step scaling, and gait asymmetry just prior to FOG. We further discuss what factors influence gait control to maintain functional gait. “Triggers”, for example, such as attention shifts or trajectory transitions, may precede FOG. We propose distinct categories of interventions and describe examples of existing work that support this idea: (a) interventions which aim to maintain a good level of locomotion control especially with respect to aspects related to FOG; (b) those that aim at avoiding FOG “triggers”; and (c) those that merely aim to escape from FOG once it occurs. The proposed theoretical framework sets the stage for testable hypotheses regarding the mechanisms that lead to FOG and may also lead to new treatment ideas. PMID:22288021

  16. Speeding up or slowing down?: Gait adaptations to preserve gait stability in response to balance perturbations

    Hak, L.; Houdijk, J.H.P.; Steenbrink, F.; van der Wurff, P.; Beek, P.J.; van Dieen, J.H.

    2012-01-01

    It has frequently been proposed that lowering walking speed is a strategy to enhance gait stability and to decrease the probability of falling. However, previous studies have not been able to establish a clear relation between walking speed and gait stability. We investigated whether people do

  17. Gait analysis following treadmill training with body weight support versus conventional physical therapy: a prospective randomized controlled single blind study.

    Lucareli, P R; Lima, M O; Lima, F P S; de Almeida, J G; Brech, G C; D'Andréa Greve, J M

    2011-09-01

    Single-blind randomized, controlled clinical study. To evaluate, using kinematic gait analysis, the results obtained from gait training on a treadmill with body weight support versus those obtained with conventional gait training and physiotherapy. Thirty patients with sequelae from traumatic incomplete spinal cord injuries at least 12 months earlier; patients were able to walk and were classified according to motor function as ASIA (American Spinal Injury Association) impairment scale C or D. Patients were divided randomly into two groups of 15 patients by the drawing of opaque envelopes: group A (weight support) and group B (conventional). After an initial assessment, both groups underwent 30 sessions of gait training. Sessions occurred twice a week, lasted for 30 min each and continued for four months. All of the patients were evaluated by a single blinded examiner using movement analysis to measure angular and linear kinematic gait parameters. Six patients (three from group A and three from group B) were excluded because they attended fewer than 85% of the training sessions. There were no statistically significant differences in intra-group comparisons among the spatial-temporal variables in group B. In group A, the following significant differences in the studied spatial-temporal variables were observed: increases in velocity, distance, cadence, step length, swing phase and gait cycle duration, in addition to a reduction in stance phase. There were also no significant differences in intra-group comparisons among the angular variables in group B. However, group A achieved significant improvements in maximum hip extension and plantar flexion during stance. Gait training with body weight support was more effective than conventional physiotherapy for improving the spatial-temporal and kinematic gait parameters among patients with incomplete spinal cord injuries.

  18. EFFECTS OF PHYSICAL REHABILITATION INTEGRATED WITH RHYTHMIC AUDITORY STIMULATION ON SPATIO-TEMPORAL AND KINEMATIC PARAMETERS OF GAIT IN PARKINSON’S DISEASE

    Massimiliano Pau

    2016-08-01

    Full Text Available Movement rehabilitation by means of physical therapy represents an essential tool in the management of gait disturbances induced by Parkinson’s disease (PD. In this context, the use of Rhythmic Auditory Stimulation (RAS has been proven useful in improving several spatio-temporal parameters, but concerning its effect on gait patterns scarce information is available from a kinematic viewpoint. In this study we used three-dimensional gait analysis based on optoelectronic stereophotogrammetry to investigate the effects of 5 weeks of intensive rehabilitation, which included gait training integrated with RAS on 26 individuals affected by PD (age 70.4±11.1, Hoehn & Yahr 1-3. Gait kinematics was assessed before and at the end of the rehabilitation period and after a three-month follow-up, using concise measures (Gait Profile Score and Gait Variable Score, GPS and GVS, respectively, which are able to describe the deviation from a physiologic gait pattern. The results confirm the effectiveness of gait training assisted by RAS in increasing speed and stride length, in regularizing cadence and correctly reweighting swing/stance phase duration. Moreover, an overall improvement of gait quality was observed, as demonstrated by the significant reduction of the GPS value, which was created mainly through significant decreases in the GVS score associated with the hip flexion-extension movement. Future research should focus on investigating kinematic details to better understand the mechanisms underlying gait disturbances in people with PD and the effects of RAS, with the aim of finding new or improving current rehabilitative treatments.

  19. Cognitive and motor dual task gait training improve dual task gait performance after stroke - A randomized controlled pilot trial.

    Liu, Yan-Ci; Yang, Yea-Ru; Tsai, Yun-An; Wang, Ray-Yau

    2017-06-22

    This study investigated effects of cognitive and motor dual task gait training on dual task gait performance in stroke. Participants (n = 28) were randomly assigned to cognitive dual task gait training (CDTT), motor dual task gait training (MDTT), or conventional physical therapy (CPT) group. Participants in CDTT or MDTT group practiced the cognitive or motor tasks respectively during walking. Participants in CPT group received strengthening, balance, and gait training. The intervention was 30 min/session, 3 sessions/week for 4 weeks. Three test conditions to evaluate the training effects were single walking, walking while performing cognitive task (serial subtraction), and walking while performing motor task (tray-carrying). Parameters included gait speed, dual task cost of gait speed (DTC-speed), cadence, stride time, and stride length. After CDTT, cognitive-motor dual task gait performance (stride length and DTC-speed) was improved (p = 0.021; p = 0.015). After MDTT, motor dual task gait performance (gait speed, stride length, and DTC-speed) was improved (p = 0.008; p = 0.008; p = 0.008 respectively). It seems that CDTT improved cognitive dual task gait performance and MDTT improved motor dual task gait performance although such improvements did not reach significant group difference. Therefore, different types of dual task gait training can be adopted to enhance different dual task gait performance in stroke.

  20. Autobiographically recalled emotional states impact forward gait initiation as a function of motivational direction.

    Fawver, Bradley; Hass, Chris J; Park, Kyoungshin D; Janelle, Christopher M

    2014-12-01

    The impact of self-generated affective states on self-initiated motor behavior remains unspecified. The purpose of the current study was to determine how self-generated emotional states impact forward gait initiation. Participants recalled past emotional experiences (anger, fear, happy, sad, and neutral), "relived" those emotional memories before gait initiation (GI), and then walked ∼4 m across the laboratory floor. Kinetic and kinematic data revealed GI characteristics consistent with a motivational direction hypothesis. Specifically, participants produced greater posterior-lateral displacement and velocity of their center of pressure (COP) during the initial phase of GI after self-generation of happy and anger emotional states relative to sad ones. During the second phase of GI, greater medial displacement of COP was found during the happy condition compared with sad, greater velocity was occasioned during happy and angry trials compared with sad, and greater velocity was exhibited after happy compared with fear memories. Finally, greater anterior velocity was produced by participants during the final phase of GI for happy and angry memories compared with sad ones. Steady state kinetic and kinematic data when recalling happy and angry memories (longer, faster, and more forceful stepping behavior) followed the anticipatory postural adjustments noted during GI. Together the results from GI and steady state gait provide robust evidence that self-generated emotional states impact forward gait behavior based on motivational direction. Endogenous manipulations of emotional states hold promise for clinical and performance interventions aimed at improving self-initiated movement.

  1. Two‐phase designs for joint quantitative‐trait‐dependent and genotype‐dependent sampling in post‐GWAS regional sequencing

    Espin‐Garcia, Osvaldo; Craiu, Radu V.

    2017-01-01

    ABSTRACT We evaluate two‐phase designs to follow‐up findings from genome‐wide association study (GWAS) when the cost of regional sequencing in the entire cohort is prohibitive. We develop novel expectation‐maximization‐based inference under a semiparametric maximum likelihood formulation tailored for post‐GWAS inference. A GWAS‐SNP (where SNP is single nucleotide polymorphism) serves as a surrogate covariate in inferring association between a sequence variant and a normally distributed quantitative trait (QT). We assess test validity and quantify efficiency and power of joint QT‐SNP‐dependent sampling and analysis under alternative sample allocations by simulations. Joint allocation balanced on SNP genotype and extreme‐QT strata yields significant power improvements compared to marginal QT‐ or SNP‐based allocations. We illustrate the proposed method and evaluate the sensitivity of sample allocation to sampling variation using data from a sequencing study of systolic blood pressure. PMID:29239496

  2. Unstable gait due to spasticity of the rectus femoris: gait analysis and motor nerve block.

    Gross, R; Leboeuf, F; Rémy-Néris, O; Perrouin-Verbe, B

    2012-12-01

    We present the case of a 54 year-old man presenting with a right Brown-Séquard plus syndrome (BSPS) after a traumatic cervical spinal cord injury. After being operated on with selective tibial neurotomy and triceps surae lengthening because of a right spastic equinus foot, he developed a gait disorder at high speed. The patient complained about an instability of the right knee. Observational gait analysis exhibited an oscillating, flexion/extension motion of the right knee during stance, which was confirmed by gait analysis. Dynamic electromyographic recordings exhibited a clonus of the right rectus femoris (RF) during stance. The spastic activity of the RF and the abnormal knee motion totally reversed after a motor nerve block of the RF, as well as after botulinum toxin type A injection into the RF. We emphasize that complex, spastic gait disorders can benefit from a comprehensive assessment including gait analysis and nerve blocks. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  3. Phase-dependent organization of postural adjustments associated with arm movements while walking.

    Nashner, L M; Forssberg, H

    1986-06-01

    This study examines the interactions between anteroposterior postural responses and the control of walking in human subjects. In the experimental paradigm, subjects walked upon a treadmill, gripping a rigid handle with one hand. Postural responses at different phases of stepping were elicited by rapid arm pulls or pushes against the handle. During arm movements, EMG's recorded the activity of representative arm, ankle, and thigh segment muscles. Strain gauges in the handle measured the force of the arm movement. A Selspot II system measured kinematics of the stepping movements. The duration of support and swing phases were marked by heel and toe switches in the soles of the subjects' shoes. In the first experiment, subjects were instructed to pull on the handle at their own pace. In these trials all subjects preferred to initiate pulls near heel strikes. Next, when instructed to pull as rapidly as possible in response to tone stimuli, reaction times were similar for all phases of the step cycle. Leg muscle responses associated with arm pulls and pushes, referred to as "postural activations," were directionally specific and preceded arm muscle activity. The temporal order and spatial distribution of postural activations in the muscles of the support leg were similar when arm pull movements occurred while the subject was standing in place and after heel strike while walking. Activations began in the ankle and radiated proximally to the thigh and then the arm. Activations of swing leg muscles were also directionally specific and involved flexion and forward or backward thrust of the limb. When arm movements were initiated during transitions from support by one leg to the other, patterns of postural activations were altered. Alterations usually occurred 10-20 ms before hell strikes and involved changes in the timing and sometimes the spatial structure of postural activations. Postural activation patterns are similar during in-place standing and during the support phase

  4. Two distinct phases of apoptosis in mammary gland involution: proteinase-independent and -dependent pathways

    Lund, Leif R; Romer, John; Thomasset, Nicole; Solberg, Helene; Pyke, Charles; Bissell, Mina J; Dano, Keld; Werb, Zena

    1996-01-01

    Postlactational involution of the mammary gland is characterized by two distinct physiological events: apoptosis of the secretory, epithelial cells undergoing programmed cell death, and proteolytic degradation of the mammary gland basement membrane. We examined the spatial and temporal patterns of apoptotic cells in relation to those of proteinases during involution of the BALB/c mouse mammary gland. Apoptosis was almost absent during lactation but became evident at day 2 of involution, when {beta}-casein gene expression was still high. Apoptotic cells were then seen at least up to day 8 of involution, when {beta}-casein gene expression was being extinguished. Expression of sulfated glycoprotein-2 (SGP-2), interleukin-1{beta} converting enzyme (ICE) and tissue inhibitor of metalloproteinases-1 was upregulated at day 2, when apoptotic cells were seen initially. Expression of the matrix metalloproteinases gelatinase A and stromelysin-1 and the serine proteinase urokinase-type plasminogen activator, which was low during lactation, was strongly upregulated in parallel starting at day 4 after weaning, coinciding with start of the collapse of the lobulo-alveolar structures and the intensive tissue remodeling in involution. The major sites of mRNA synthesis for these proteinases were fibroblast-like cells in the periductal stroma and stromal cells surrounding the collapsed alveoli, suggesting that the degradative phase of involution is due to a specialized mesenchymal-epithelial interaction. To elucidate the functional role of these proteinases during involution, at the onset of weaning we treated mice systemically with the glucocorticoid hydrocortisone, which is known to inhibit mammary gland involution. Although the initial wave of apoptotic cells appeared in the lumina of the gland, the dramatic regression and tissue remodeling usually evident by day 5 was substantially inhibited by systemic treatment with hydrocortisone. mRNA and protein for gelatinase A, stromelysin

  5. Coherence-enhanced phase-dependent dissipation in long SNS Josephson junctions: Revealing Andreev bound state dynamics

    Dassonneville, B.; Murani, A.; Ferrier, M.; Guéron, S.; Bouchiat, H.

    2018-05-01

    One of the best known causes of dissipation in ac-driven quantum systems stems from photon absorption causing transitions between levels. Dissipation can also be caused by the retarded response to the time-dependent excitation, and in general gives insight into the system's relaxation times and mechanisms. Here we address the dissipation in a mesoscopic normal wire with superconducting contacts, that sustains a dissipationless supercurrent at zero frequency and that may therefore naively be expected to remain dissipationless at a frequency lower than the superconducting gap. We probe the high-frequency linear response of such a normal metal/superconductor (NS) ring to a time-dependent flux by coupling it to a highly sensitive multimode microwave resonator. Far from being the simple, dissipationless derivative of the supercurrent-versus-phase relation, the ring's ac susceptibility also displays a dissipative component whose phase dependence is a signature of the dynamical processes occurring within the Andreev spectrum. We show how dissipation is driven by the competition between two mechanisms. The first is the relaxation of the Andreev level distribution function, while the second corresponds to microwave-induced transitions within the spectrum. Depending on the relative strength of those contributions, dissipation can be maximal at π , a phase at which the proximity-induced minigap closes, or can be maximal near π /2 , a phase at which the dc supercurrent is maximal. We also find that the dissipative response paradoxically increases at low temperature and can even exceed the normal-state conductance. The results are successfully confronted with theoretical predictions of the Kubo linear response and time-dependent Usadel equations, derived from the Bogoliubov-de Gennes Hamiltonian describing the SNS junction. These experiments thus demonstrate the power of the ac susceptibility measurement of individual hybrid mesoscopic systems in probing in a controlled way

  6. A Validated Smartphone-Based Assessment of Gait and Gait Variability in Parkinson's Disease.

    Robert J Ellis

    Full Text Available A well-established connection exists between increased gait variability and greater fall likelihood in Parkinson's disease (PD; however, a portable, validated means of quantifying gait variability (and testing the efficacy of any intervention remains lacking. Furthermore, although rhythmic auditory cueing continues to receive attention as a promising gait therapy for PD, its widespread delivery remains bottlenecked. The present paper describes a smartphone-based mobile application ("SmartMOVE" to address both needs.The accuracy of smartphone-based gait analysis (utilizing the smartphone's built-in tri-axial accelerometer and gyroscope to calculate successive step times and step lengths was validated against two heel contact-based measurement devices: heel-mounted footswitch sensors (to capture step times and an instrumented pressure sensor mat (to capture step lengths. 12 PD patients and 12 age-matched healthy controls walked along a 26-m path during self-paced and metronome-cued conditions, with all three devices recording simultaneously.Four outcome measures of gait and gait variability were calculated. Mixed-factorial analysis of variance revealed several instances in which between-group differences (e.g., increased gait variability in PD patients relative to healthy controls yielded medium-to-large effect sizes (eta-squared values, and cueing-mediated changes (e.g., decreased gait variability when PD patients walked with auditory cues yielded small-to-medium effect sizes-while at the same time, device-related measurement error yielded small-to-negligible effect sizes.These findings highlight specific opportunities for smartphone-based gait analysis to serve as an alternative to conventional gait analysis methods (e.g., footswitch systems or sensor-embedded walkways, particularly when those methods are cost-prohibitive, cumbersome, or inconvenient.

  7. Effect of Time-Dependent Pinning Pressure on Abnormal Grain Growth: Phase Field Simulation

    Kim, Jeong Min; Min, Guensik; Shim, Jae-Hyeok; Lee, Kyung Jong

    2018-05-01

    The effect of the time-dependent pinning pressure of precipitates on abnormal grain growth has been investigated by multiphase field simulation with a simple precipitation model. The application of constant pinning pressure is problematic because it always induces abnormal grain growth or no grain growth, which is not reasonable considering the real situation. To produce time-dependent pinning pressure, both precipitation kinetics and precipitate coarsening kinetics have been considered with two rates: slow and fast. The results show that abnormal grain growth is suppressed at the slow precipitation rate. At the slow precipitation rate, the overall grain growth caused by the low pinning pressure in the early stage indeed plays a role in preventing abnormal grain growth by reducing the mobility advantage of abnormal grains. In addition, the fast precipitate coarsening rate tends to more quickly transform abnormal grain growth into normal grain growth by inducing the active growth of grains adjacent to the abnormal grains in the early stage. Therefore, the present study demonstrates that the time dependence of the pinning pressure of precipitates is a critical factor that determines the grain growth mode.

  8. Proteomic analysis of growth phase-dependent expression of Legionella pneumophila proteins which involves regulation of bacterial virulence traits.

    Tsuyoshi Hayashi

    Full Text Available Legionella pneumophila, which is a causative pathogen of Legionnaires' disease, expresses its virulent traits in response to growth conditions. In particular, it is known to become virulent at a post-exponential phase in vitro culture. In this study, we performed a proteomic analysis of differences in expression between the exponential phase and post-exponential phase to identify candidates associated with L. pneumophila virulence using 2-Dimentional Fluorescence Difference Gel Electrophoresis (2D-DIGE combined with Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry (MALDI-TOF-MS. Of 68 identified proteins that significantly differed in expression between the two growth phases, 64 were up-regulated at a post-exponential phase. The up-regulated proteins included enzymes related to glycolysis, ketone body biogenesis and poly-3-hydroxybutyrate (PHB biogenesis, suggesting that L. pneumophila may utilize sugars and lipids as energy sources, when amino acids become scarce. Proteins related to motility (flagella components and twitching motility-associated proteins were also up-regulated, predicting that they enhance infectivity of the bacteria in host cells under certain conditions. Furthermore, 9 up-regulated proteins of unknown function were found. Two of them were identified as novel bacterial factors associated with hemolysis of sheep red blood cells (SRBCs. Another 2 were found to be translocated into macrophages via the Icm/Dot type IV secretion apparatus as effector candidates in a reporter assay with Bordetella pertussis adenylate cyclase. The study will be helpful for virulent analysis of L. pneumophila from the viewpoint of physiological or metabolic modulation dependent on growth phase.

  9. Non-linear temperature-dependent curvature of a phase change composite bimorph beam

    Blonder, Greg

    2017-06-01

    Bimorph films curl in response to temperature. The degree of curvature typically varies in proportion to the difference in thermal expansion of the individual layers, and linearly with temperature. In many applications, such as controlling a thermostat, this gentle linear behavior is acceptable. In other cases, such as opening or closing a valve or latching a deployable column into place, an abrupt motion at a fixed temperature is preferred. To achieve this non-linear motion, we describe the fabrication and performance of a new bilayer structure we call a ‘phase change composite bimorph (PCBM)’. In a PCBM, one layer in the bimorph is a composite containing small inclusions of phase change materials. When the inclusions melt, their large (generally positive and  >1%) expansion coefficient induces a strong, reversible step function jump in bimorph curvature. The measured jump amplitude and thermal response is consistent with theory, and can be harnessed by a new class of actuators and sensors.

  10. Effects of balance ability and handgrip height on kinematics of the gait, torso, and pelvis in elderly women using a four-wheeled walker.

    Choi, Hyuk-Jae; Ko, Chang-Yong; Kang, Sungjae; Ryu, Jeicheong; Mun, Museong; Jeon, Hye-Seon

    2015-02-01

    Numerous elderly individuals use the four-wheeled walker (FWW) as a gait-assistive device. The walker's handgrip height is important for correct use. However, few clinical studies have investigated the biomechanical effects of the FWW's handgrip height on balance. Therefore, the present study assessed kinematic features of the gait, torso and pelvis during use of the FWW at two levels of handgrip height (48% vs 55% of the subject's height) while assessing balance in older adults. A total of 20 older adults were allocated into two groups according to the Berg Balance Scale (BBS): good balance (GB; BBS≥46) versus poor balance (PB; BBS<45). Participants walked with the FWW at 48% or 55% handgrip height for 10 m. Our study showed that the double-support period and stance phase significantly increased at 55% handgrip height, but the swing phase significantly decreased in the GB group. In the PB group, velocity and stride length significantly increased at 55% handgrip height. Tilt angle of the torso in the GB group was significantly lower at 55% than at 48% handgrip height, but no differences were observed in the PB group. In the pelvis, initial contact and toe-off angles of tilt were lower in the GB group at 55% handgrip height, but no differences were observed in the PB group. These results showed that kinematic features of the gait, torso, and pelvis in older adults using the FWW might be dependent on the handgrip height of the FWW and the patient's balance. Additionally, greater than 48% of the body height might be appropriate for older adults with poor balance. © 2014 Japan Geriatrics Society.

  11. Probing phase- and frequency-dependent characteristics of cortical interneurons using combined transcranial alternating current stimulation and transcranial magnetic stimulation.

    Hussain, Sara J; Thirugnanasambandam, Nivethida

    2017-06-01

    Paired-pulse transcranial magnetic stimulation (TMS) and peripheral stimulation combined with TMS can be used to study cortical interneuronal circuitry. By combining these procedures with concurrent transcranial alternating current stimulation (tACS), Guerra and colleagues recently showed that different cortical interneuronal populations are differentially modulated by the phase and frequency of tACS-imposed oscillations (Guerra A, Pogosyan A, Nowak M, Tan H, Ferreri F, Di Lazzaro V, Brown P. Cerebral Cortex 26: 3977-2990, 2016). This work suggests that different cortical interneuronal populations can be characterized by their phase and frequency dependency. Here we discuss how combining TMS and tACS can reveal the frequency at which cortical interneuronal populations oscillate, the neuronal origins of behaviorally relevant cortical oscillations, and how entraining cortical oscillations could potentially treat brain disorders. Copyright © 2017 the American Physiological Society.

  12. Effects of ACTH on corticosteroid and progesterone levels in female baboons depending on the phase of the menstrual cycle

    Todua, T.N.; Goncharov, N.P.; Katsiya, G.V.; Lapin, B.A.; Vorontsov, V.I.

    1986-01-01

    To study the effect of ACTH on the endocrine function of steroid producing glands depending on the level of sex hormones in the body, a comparative study of the dynamics of steroid hormones in the follicular and luteal phases of the menstrual cycle in response to a standard does of ACTH was undertaken in experiments on hamadryad baboons. Concentrations of corticosterone, 11-deoxycortisol, and progesterone were determined in duplicate samples of plasma by radioimmunoassay. It is shown that the sensitivity of the adrenals to a single injection of ACTH is independent of the phase of the menstrual cycle and the inhibitory effects of ACTH on progesterone secretion is exhibited only in the presence of an actively functioning corpus luteus of the ovary

  13. Effects of ACTH on corticosteroid and progesterone levels in female baboons depending on the phase of the menstrual cycle

    Todua, T.N.; Goncharov, N.P.; Katsiya, G.V.; Lapin, B.A.; Vorontsov, V.I.

    1986-01-01

    To study the effect of ACTH on the endocrine function of steroid producing glands depending on the level of sex hormones in the body, a comparative study of the dynamics of steroid hormones in the follicular and luteal phases of the menstrual cycle in response to a standard does of ACTH was undertaken in experiments on hamadryad baboons. Concentrations of corticosterone, 11-deoxycortisol, and progesterone were determined in duplicate samples of plasma by radioimmunoassay. It is shown that the sensitivity of the adrenals to a single injection of ACTH is independent of the phase of the menstrual cycle and the inhibitory effects of ACTH on progesterone secretion is exhibited only in the presence of an actively functioning corpus luteus of the ovary.

  14. Real-time subject-specific monitoring of internal deformations and stresses in the soft tissues of the foot: a new approach in gait analysis.

    Yarnitzky, G; Yizhar, Z; Gefen, A

    2006-01-01

    No technology is presently available to provide real-time information on internal deformations and stresses in plantar soft tissues of individuals during evaluation of the gait pattern. Because internal deformations and stresses in the plantar pad are critical factors in foot injuries such as diabetic foot ulceration, this severely limits evaluation of patients. To allow such real-time subject-specific analysis, we developed a hierarchal modeling system which integrates a two-dimensional gross structural model of the foot (high-order model) with local finite element (FE) models of the plantar tissue padding the calcaneus and medial metatarsal heads (low-order models). The high-order whole-foot model provides real-time analytical evaluations of the time-dependent plantar fascia tensile forces during the stance phase. These force evaluations are transferred, together with foot-shoe local reaction forces, also measured in real time (under the calcaneus, medial metatarsals and hallux), to the low-order FE models of the plantar pad, where they serve as boundary conditions for analyses of local deformations and stresses in the plantar pad. After careful verification of our custom-made FE solver and of our foot model system with respect to previous literature and against experimental results from a synthetic foot phantom, we conducted human studies in which plantar tissue loading was evaluated in real time during treadmill gait in healthy individuals (N = 4). We concluded that internal deformations and stresses in the plantar pad during gait cannot be predicted from merely measuring the foot-shoe force reactions. Internal loading of the plantar pad is constituted by a complex interaction between the anatomical structure and mechanical behavior of the foot skeleton and soft tissues, the body characteristics, the gait pattern and footwear. Real-time FE monitoring of internal deformations and stresses in the plantar pad is therefore required to identify elevated deformation

  15. Phase-dependent optical bistability and multistability in a semiconductor quantum well system

    Wang Zhiping; Fan Hongyi

    2010-01-01

    We theoretically investigate the hybrid absorptive-dispersive optical bistability and multistability in a four-level inverted-Y quantum well system inside a unidirectional ring cavity. We find that the coupling field, the pumping field as well as the cycling field can affect the optical bistability and multistability dramatically, which can be used to manipulate efficiently the threshold intensity and the hysteresis loop. The effects of the relative phase and the electronic cooperation parameter on the OB and OM are also studied. Our study is much more practical than its atomic counterpart due to its flexible design and the wide adjustable parameters. Thus, it may provide some new possibilities for technological applications in optoelectronics and solid-state quantum information science.

  16. Gain length dependence on phase shake in the VUV-FEL at the TESLA Test Facility

    Pflueger, J. [DESY/HASYLAB, Hamburg (Germany); Schneidmiller, E.A. [Automatic Systems Corporation, Samara (Russian Federation); Pierini, P. [INFN, Milano (Italy)

    1995-12-31

    The TTF VUV FEL, which is in its design stage at DESY, consists of a 30 m long SASE FEL which will radiate around 6 nm, driven by a superconducting linac with final energy of 1 GeV. One of the important issues in its design is the undulator performance, which is studied in this paper. The present setup, including FODO lattice, is discussed in this paper. Results of simulations, including the realistic wiggler field errors and beam stearing, are presented. Dependence of the performance, in particular the gain and saturation length as well as the saturation peak power, on the wiggler field errors is discussed.

  17. Differential effects of absent visual feedback control on gait variability during different locomotion speeds.

    Wuehr, M; Schniepp, R; Pradhan, C; Ilmberger, J; Strupp, M; Brandt, T; Jahn, K

    2013-01-01

    Healthy persons exhibit relatively small temporal and spatial gait variability when walking unimpeded. In contrast, patients with a sensory deficit (e.g., polyneuropathy) show an increased gait variability that depends on speed and is associated with an increased fall risk. The purpose of this study was to investigate the role of vision in gait stabilization by determining the effects of withdrawing visual information (eyes closed) on gait variability at different locomotion speeds. Ten healthy subjects (32.2 ± 7.9 years, 5 women) walked on a treadmill for 5-min periods at their preferred walking speed and at 20, 40, 70, and 80 % of maximal walking speed during the conditions of walking with eyes open (EO) and with eyes closed (EC). The coefficient of variation (CV) and fractal dimension (α) of the fluctuations in stride time, stride length, and base width were computed and analyzed. Withdrawing visual information increased the base width CV for all walking velocities (p < 0.001). The effects of absent visual information on CV and α of stride time and stride length were most pronounced during slow locomotion (p < 0.001) and declined during fast walking speeds. The results indicate that visual feedback control is used to stabilize the medio-lateral (i.e., base width) gait parameters at all speed sections. In contrast, sensory feedback control in the fore-aft direction (i.e., stride time and stride length) depends on speed. Sensory feedback contributes most to fore-aft gait stabilization during slow locomotion, whereas passive biomechanical mechanisms and an automated central pattern generation appear to control fast locomotion.

  18. Temperature dependence of positron lifetime in the two-mixed-phase Bi-Sr-Ca-Cu-O superconductor

    Zhang, D.M.; Tang, C.Q.; Gen, T.; Li, G.Y.

    1993-01-01

    As compared with the YBaCuO(123) system, the studies of positron annihilation performed for other cuprate superconductors, specifically for the BiSrCaCuO and TlBaCa.CuO systems, are very few. Thus further study of positron annihilation in BiSrCaCuO and TlBaCaCuO systems is necessary. In this note, we report the results of the temperature dependence of positron lifetime parameters in the two-mixed-phase system BiSrCaCuO and discuss the results. (orig.)

  19. Phase transition and angular momentum dependence of correlations in the rotational spectra of Ne20 and Ne22

    Satpathy, L.; Schmid, K.W.; Krewald, S.; Faessler, A.

    1974-01-01

    Multi-Configuration-Hartree-Fock (MCHF) calculations with angular momentum projection before the variation of the internal degree of freedom have been performed for the nuclei Ne 20 and Ne 22 . This procedure yields different correlated intrinsic states for the different members of a rotational band. Thus, the angular momentum dependence of correlations has been studied. Experimentally, the ground state spectra of Ne 20 and Ne 22 show properties similar to the phase transitions observed in some rare earth nuclei which have been well reproduced through the present calculations. The calculated spectra show a significant improvement compared to the ones obtained by variation before the angular momentum projection is effected. (author)

  20. Gait Recognition Using Image Self-Similarity

    Chiraz BenAbdelkader

    2004-04-01

    Full Text Available Gait is one of the few biometrics that can be measured at a distance, and is hence useful for passive surveillance as well as biometric applications. Gait recognition research is still at its infancy, however, and we have yet to solve the fundamental issue of finding gait features which at once have sufficient discrimination power and can be extracted robustly and accurately from low-resolution video. This paper describes a novel gait recognition technique based on the image self-similarity of a walking person. We contend that the similarity plot encodes a projection of gait dynamics. It is also correspondence-free, robust to segmentation noise, and works well with low-resolution video. The method is tested on multiple data sets of varying sizes and degrees of difficulty. Performance is best for fronto-parallel viewpoints, whereby a recognition rate of 98% is achieved for a data set of 6 people, and 70% for a data set of 54 people.

  1. Gait Recognition Based on Outermost Contour

    Lili Liu

    2011-10-01

    Full Text Available Gait recognition aims to identify people by the way they walk. In this paper, a simple but e ective gait recognition method based on Outermost Contour is proposed. For each gait image sequence, an adaptive silhouette extraction algorithm is firstly used to segment the frames of the sequence and a series of postprocessing is applied to obtain the normalized silhouette images with less noise. Then a novel feature extraction method based on Outermost Contour is performed. Principal Component Analysis (PCA is adopted to reduce the dimensionality of the distance signals derived from the Outermost Contours of silhouette images. Then Multiple Discriminant Analysis (MDA is used to optimize the separability of gait features belonging to di erent classes. Nearest Neighbor (NN classifier and Nearest Neighbor classifier with respect to class Exemplars (ENN are used to classify the final feature vectors produced by MDA. In order to verify the e ectiveness and robustness of our feature extraction algorithm, we also use two other classifiers: Backpropagation Neural Network (BPNN and Support Vector Machine (SVM for recognition. Experimental results on a gait database of 100 people show that the accuracy of using MDA, BPNN and SVM can achieve 97.67%, 94.33% and 94.67%, respectively.

  2. Gait Characteristics in Adolescents With Multiple Sclerosis.

    Kalron, Alon; Frid, Lior; Menascu, Shay

    2017-03-01

    Multiple sclerosis is a progressive autoimmune disease of the central nervous system. A presentation of multiple sclerosis before age18 years has traditionally been thought to be rare. However, during the past decade, more cases have been reported. We examined gait characteristics in 24 adolescents with multiple sclerosis (12 girls, 12 boys). Mean disease duration was 20.4 (S.D. = 24.9) months and mean age was 15.5 (S.D. = 1.1) years. The mean expanded disability status scale score was 1.7 (S.D. = 0.7) indicating minimal disability. Outcomes were compared with gait and the gait variability index value of healthy age-matched adolescents. Adolescents with multiple sclerosis walked slower with a wider base of support compared with age-matched healthy control subjects. Moreover, the gait variability index was lower in the multiple sclerosis group compared with the values in the healthy adolescents: 85.4 (S.D. = 8.1) versus 96.5 (S.D. = 7.4). We present gait parameters of adolescents with multiple sclerosis. From a clinical standpoint, our data could improve management of walking dysfunction in this relatively young population. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Development and decline of upright gait stability

    Marco eIosa

    2014-02-01

    Full Text Available Upright gait is a peculiar characteristic of humans that requires the ability to manage upper body dynamic balance while walking, despite the perturbations that are generated by movements of the lower limbs. Most of the studies on upright gait stability have compared young adults and the elderly to determine the effects of aging. In other studies the comparison was between healthy subjects and patients to examine specific pathologies. Fewer researches have also investigated the development of upright gait stability in children.This review discusses these studies in order to provide an overview of this relevant aspect of human locomotion. A clear trend from development to decline of upright gait stability has been depicted across the entire lifespan, from toddlers at first steps to elderly. In old individuals, even if healthy, the deterioration of skeletal muscle, combined with sensorial and cognitive performance, reduces the ability to maintain an upright trunk during walking, increasing the instability and the risk of falls. Further, the pathological causes of altered development or of a sudden loss of gait stability, as well as the environmental influence are investigated. The last part of this review is focused on the control of upper body accelerations during walking, a particularly interesting topic for the recent development of low-cost wearable accelerometers.

  4. Relationships of stroke patients' gait parameters with fear of falling.

    Park, Jin; Yoo, Ingyu

    2014-12-01

    [Purpose] The purpose of this study was to assess the correlation of gait parameters with fear of falling in stroke survivors. [Subjects] In total, 12 patients with stroke participated. [Methods] The subjects performed on a Biodex Gait Trainer 2 for 5 min to evaluate characteristic gait parameters. The kinematic gait parameters measured were gait speed, step cycle, step length, and time on each foot (step symmetry). All the subjects also completed a fall anxiety survey. [Results] Correlations between gait parameters and fear of falling scores were calculated. There was a moderate degree of correlation between fear of falling scores and the step cycle item of gait parameters. [Conclusions] According to our results, the step cycle gait parameter may be related to increased fall anxiety.

  5. Porcine epidemic diarrhea virus through p53-dependent pathway causes cell cycle arrest in the G0/G1 phase.

    Sun, Pei; Wu, Haoyang; Huang, Jiali; Xu, Ying; Yang, Feng; Zhang, Qi; Xu, Xingang

    2018-05-22

    Porcine epidemic diarrhea virus (PEDV), an enteropathogenic Alphacoronavirus, has caused enormous economic losses in the swine industry. p53 protein exists in a wide variety of animal cells, which is involved in cell cycle regulation, apoptosis, cell differentiation and other biological functions. In this study, we investigated the effects of PEDV infection on the cell cycle of Vero cells and p53 activation. The results demonstrated that PEDV infection induces cell cycle arrest at G0/G1 phase in Vero cells, while UV-inactivated PEDV does not cause cell cycle arrest. PEDV infection up-regulates the levels of p21, cdc2, cdk2, cdk4, Cyclin A protein and down-regulates Cyclin E protein. Further research results showed that inhibition of p53 signaling pathway can reverse the cell cycle arrest in G0/G1 phase induced by PEDV infection and cancel out the up-regulation of p21 and corresponding Cyclin/cdk mentioned above. In addition, PEDV infection of the cells synchronized in various stages of cell cycle showed that viral subgenomic RNA and virus titer were higher in the cells released from G0/G1 phase synchronized cells than that in the cells released from the G1/S phase and G2/M phase synchronized or asynchronous cells after 18 h p.i.. This is the first report to demonstrate that the p53-dependent pathway plays an important role in PEDV induced cell cycle arrest and beneficially contributes to viral infection. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Chemical dynamics in the gas phase: Time-dependent quantum mechanics of chemical reactions

    Gray, S.K. [Argonne National Laboratory, IL (United States)

    1993-12-01

    A major goal of this research is to obtain an understanding of the molecular reaction dynamics of three and four atom chemical reactions using numerically accurate quantum dynamics. This work involves: (i) the development and/or improvement of accurate quantum mechanical methods for the calculation and analysis of the properties of chemical reactions (e.g., rate constants and product distributions), and (ii) the determination of accurate dynamical results for selected chemical systems, which allow one to compare directly with experiment, determine the reliability of the underlying potential energy surfaces, and test the validity of approximate theories. This research emphasizes the use of recently developed time-dependent quantum mechanical methods, i.e. wave packet methods.

  7. Ikaros is degraded by proteasome-dependent mechanism in the early phase of apoptosis induction

    He, Li-Cai; Xu, Han-Zhang; Gu, Zhi-Min; Liu, Chuan-Xu; Chen, Guo-Qiang; Wang, Yue-Fei; Wen, Dong-Hua; Wu, Ying-Li

    2011-01-01

    Research highlights: → Chemotherapeutic drugs or UV treatment reduces Ikaros prior to caspase-3 activation. → Etoposide treatment does not alter the mRNA but shortens the half-life of Ikaros. → MG132 or epoxomicin but not calpeptin inhibits etoposide-induced Ikaros degradation. → Overexpression of Ikaros accelerates etoposide-induced apoptosis in NB4 cells. -- Abstract: Ikaros is an important transcription factor involved in the development and differentiation of hematopoietic cells. In this work, we found that chemotherapeutic drugs or ultraviolet radiation (UV) treatment could reduce the expression of full-length Ikaros (IK1) protein in less than 3 h in leukemic NB4, Kasumi-1 and Jurkat cells, prior to the activation of caspase-3. Etoposide treatment could not alter the mRNA level of IK1 but it could shorten the half-life of IK1. Co-treatment with the proteasome inhibitor MG132 or epoxomicin but not calpain inhibitor calpeptin inhibited etoposide-induced Ikaros downregulation. Overexpression of IK1 could accelerate etoposide-induced apoptosis in NB4 cells, as evidenced by the increase of Annexin V positive cells and the more early activation of caspase 3. To our knowledge, this is the first report to show that upon chemotherapy drugs or UV treatment, IK1 could be degraded via the proteasome system in the early phase of apoptosis induction. These data might shed new insight on the role of IK1 in apoptosis and the post-translational regulation of IK1.

  8. Size- and phase-dependent mechanical properties of ultrathin Si films on polyimide substrates

    Schlich, Franziska F.; Spolenak, Ralph

    2016-01-01

    Ultrathin Si films in the nanometer range are extensively used for electronic and optoelectronic devices. Their mechanical properties have a high impact on the durability of the devices during lifetime. Here, fragmentation and buckling of 8–103 nm thin amorphous and polycrystalline (poly-) Si films on polyimide substrates have been studied by in situ light microscopy, Raman spectroscopy and resistance measurements. Generally, a smaller film thickness and a compressive residual stress delays the fracture of the film. The fracture strength of poly-Si films is larger compared to that of amorphous Si films while the adhesion to the substrate is better for amorphous Si compared to poly-Si. The onset delamination as a function of film thickness differs for the two phases and is described by two different models. Thin-film models for fracture toughness (amorphous Si: K 1C  = 1.49 ± 0.22, poly-Si: K 1C  = 3.36 ± 1.37) are applied, discussed, and found to be consistent with literature values.

  9. Doping dependence of an excitonic-driven CDW phase in 1T-TiSe2

    Chen, Chuan; Pereira, Vitor

    The origin of the robust charge density wave (CDW) phase in this system has been a perennial source of new ideas, concepts, and controversy. A foremost and recurring question has been whether the CDW instability is primarily driven by electron-electron or electron-phonon interactions. Whereas it is clear that both ultimately play an important role in its overall electronic, lattice, and transport properties, the very low carrier density and particular CDW wavevector of this system has led to the suggestion that electron-electron interactions can be the dominant factor driving the CDW instability through a transition to an excitonic insulator state. By gathering the latest quantitative information about the bandstructure parameters from ARPES and performing a self-consistent Hartree-Fock calculation as a function of doping and temperature, we demonstrate that electron-electron interactions alone can explain very well the variation of Tc with electron doping seen in recent experiments up to densities where the superconducting dome emerges. In addition, the renormalized bandstructure predicted by our model provides a consistent interpretation for the development of partial gaps and the changes in the nature of charge carriers that are known, experimentally, to take place near Tc. This work was supported by the Singapore National Research Foundation under Grant NRF-CRP6-2010-05.

  10. Development of gait segmentation methods for wearable foot pressure sensors.

    Crea, S; De Rossi, S M M; Donati, M; Reberšek, P; Novak, D; Vitiello, N; Lenzi, T; Podobnik, J; Munih, M; Carrozza, M C

    2012-01-01

    We present an automated segmentation method based on the analysis of plantar pressure signals recorded from two synchronized wireless foot insoles. Given the strict limits on computational power and power consumption typical of wearable electronic components, our aim is to investigate the capability of a Hidden Markov Model machine-learning method, to detect gait phases with different levels of complexity in the processing of the wearable pressure sensors signals. Therefore three different datasets are developed: raw voltage values, calibrated sensor signals and a calibrated estimation of total ground reaction force and position of the plantar center of pressure. The method is tested on a pool of 5 healthy subjects, through a leave-one-out cross validation. The results show high classification performances achieved using estimated biomechanical variables, being on average the 96%. Calibrated signals and raw voltage values show higher delays and dispersions in phase transition detection, suggesting a lower reliability for online applications.

  11. The Parkinsonian Gait Spatiotemporal Parameters Quantified by a Single Inertial Sensor before and after Automated Mechanical Peripheral Stimulation Treatment

    Ana Kleiner

    2015-01-01

    Full Text Available This study aims to evaluate the change in gait spatiotemporal parameters in subjects with Parkinson’s disease (PD before and after Automated Mechanical Peripheral Stimulation (AMPS treatment. Thirty-five subjects with PD and 35 healthy age-matched subjects took part in this study. A dedicated medical device (Gondola was used to administer the AMPS. All patients with PD were treated in off levodopa phase and their gait performances were evaluated by an inertial measurement system before and after the intervention. The one-way ANOVA for repeated measures was performed to assess the differences between pre- and post-AMPS and the one-way ANOVA to assess the differences between PD patients and the control group. Spearman’s correlations assessed the associations between patients with PD clinical status (H&Y and the percentage of improvement of the gait variables after AMPS (α<0.05 for all tests. The PD group had an improvement of 14.85% in the stride length; 14.77% in the gait velocity; and 29.91% in the gait propulsion. The correlation results showed that the higher the H&Y classification, the higher the stride length percentage of improvement. The treatment based on AMPS intervention seems to induce a better performance in the gait pattern of PD patients, mainly in intermediate and advanced stages of the condition.

  12. Adaptive locomotor training on an end-effector gait robot: evaluation of the ground reaction forces in different training conditions.

    Tomelleri, Christopher; Waldner, Andreas; Werner, Cordula; Hesse, Stefan

    2011-01-01

    The main goal of robotic gait rehabilitation is the restoration of independent gait. To achieve this goal different and specific patterns have to be practiced intensively in order to stimulate the learning process of the central nervous system. The gait robot G-EO Systems was designed to allow the repetitive practice of floor walking, stair climbing and stair descending. A novel control strategy allows training in adaptive mode. The force interactions between the foot and the ground were analyzed on 8 healthy volunteers in three different conditions: real floor walking on a treadmill, floor walking on the gait robot in passive mode, floor walking on the gait robot in adaptive mode. The ground reaction forces were measured by a Computer Dyno Graphy (CDG) analysis system. The results show different intensities of the ground reaction force across all of the three conditions. The intensities of force interactions during the adaptive training mode are comparable to the real walking on the treadmill. Slight deviations still occur in regard to the timing pattern of the forces. The adaptive control strategy comes closer to the physiological swing phase than the passive mode and seems to be a promising option for the treatment of gait disorders. Clinical trials will validate the efficacy of this new option in locomotor therapy on the patients. © 2011 IEEE

  13. Prediction of human gait trajectories during the SSP using a neuromusculoskeletal modeling: A challenge for parametric optimization.

    Seyed, Mohammadali Rahmati; Mostafa, Rostami; Borhan, Beigzadeh

    2018-04-27

    The parametric optimization techniques have been widely employed to predict human gait trajectories; however, their applications to reveal the other aspects of gait are questionable. The aim of this study is to investigate whether or not the gait prediction model is able to justify the movement trajectories for the higher average velocities. A planar, seven-segment model with sixteen muscle groups was used to represent human neuro-musculoskeletal dynamics. At first, the joint angles, ground reaction forces (GRFs) and muscle activations were predicted and validated for normal average velocity (1.55 m/s) in the single support phase (SSP) by minimizing energy expenditure, which is subject to the non-linear constraints of the gait. The unconstrained system dynamics of extended inverse dynamics (USDEID) approach was used to estimate muscle activations. Then by scaling time and applying the same procedure, the movement trajectories were predicted for higher average velocities (from 2.07 m/s to 4.07 m/s) and compared to the pattern of movement with fast walking speed. The comparison indicated a high level of compatibility between the experimental and predicted results, except for the vertical position of the center of gravity (COG). It was concluded that the gait prediction model can be effectively used to predict gait trajectories for higher average velocities.

  14. Generating Human-Like Velocity-Adapted Jumping Gait from sEMG Signals for Bionic Leg’s Control

    Weiwei Yu

    2017-01-01

    Full Text Available In the case of dynamic motion such as jumping, an important fact in sEMG (surface Electromyogram signal based control on exoskeletons, myoelectric prostheses, and rehabilitation gait is that multichannel sEMG signals contain mass data and vary greatly with time, which makes it difficult to generate compliant gait. Inspired by the fact that muscle synergies leading to dimensionality reduction may simplify motor control and learning, this paper proposes a new approach to generate flexible gait based on muscle synergies extracted from sEMG signal. Two questions were discussed and solved, the first one concerning whether the same set of muscle synergies can explain the different phases of hopping movement with various velocities. The second one is about how to generate self-adapted gait with muscle synergies while alleviating model sensitivity to sEMG transient changes. From the experimental results, the proposed method shows good performance both in accuracy and in robustness for producing velocity-adapted vertical jumping gait. The method discussed in this paper provides a valuable reference for the sEMG-based control of bionic robot leg to generate human-like dynamic gait.

  15. Skeletal and Clinical Effects of Exoskeleton-Assisted Gait

    2015-10-01

    robotic exoskeletons to enable gait in individuals with a complete spinal cord injury, the health benefits of exoskeleton -assisted gait have not been...for the use of robotic exoskeletons to enable gait in individuals with a complete spinal cord injury, clinical teams are not provided with...appropriate tools to estimate or predict potential health benefits (e.g. bone health) associated with exoskeleton -assisted gait. What was the impact on other

  16. Learning new gait patterns: Exploratory muscle activity during motor learning is not predicted by motor modules

    Ranganathan, Rajiv; Krishnan, Chandramouli; Dhaher, Yasin Y.; Rymer, William Z.

    2018-01-01

    The motor module hypothesis in motor control proposes that the nervous system can simplify the problem of controlling a large number of muscles in human movement by grouping muscles into a smaller number of modules. Here, we tested one prediction of the modular organization hypothesis by examining whether there is preferential exploration along these motor modules during the learning of a new gait pattern. Healthy college-aged participants learned a new gait pattern which required increased hip and knee flexion during the swing phase while walking in a lower-extremity robot (Lokomat). The new gait pattern was displayed as a foot trajectory in the sagittal plane and participants attempted to match their foot trajectory to this template. We recorded EMG from 8 lower-extremity muscles and we extracted motor modules during both baseline walking and target-tracking using non-negative matrix factorization (NMF). Results showed increased trajectory variability in the first block of learning, indicating that participants were engaged in exploratory behavior. Critically, when we examined the muscle activity during this exploratory phase, we found that the composition of motor modules changed significantly within the first few strides of attempting the new gait pattern. The lack of persistence of the motor modules under even short time scales suggests that motor modules extracted during locomotion may be more indicative of correlated muscle activity induced by the task constraints of walking, rather than reflecting a modular control strategy. PMID:26916510

  17. Quantifying Gait Impairment Using an Instrumented Treadmill in People with Multiple Sclerosis

    Kalron, Alon; Dvir, Zeevi; Frid, Lior; Achiron, Anat

    2013-01-01

    Background and Objective. Treadmill gait analysis has been proposed as an attractive alternative for overground walking measuring systems. The purpose of this study was twofold: first to determine spatiotemporal parameters of treadmill gait in patients with multiple sclerosis (MS) and second to examine whether these parameters are associated with specific functional impairments in this cohort. Method. Eighty-seven relapsing-remitting patients diagnosed with MS, 50 women and 37 men, aged 40.9 ± 11.9 with an expanded disability status scale (EDSS) score of 2.7 ± 1.6, participated in this study. Twenty-five apparently healthy subjects, 14 women and 11 men, aged 38.5 ± 9.4, served as controls. Spatiotemporal gait parameters were obtained using the Zebris FDM-T Treadmill (Zebris Medical GmbH, Germany). People with MS demonstrated significantly shorter steps, extended stride time, wider base of support, longer step time, reduced single support phase, and a prolonged double support phase compared to the healthy controls. The EDSS score was significantly correlated with all spatiotemporal gait parameters. Conclusion. The instrumented treadmill may be an effective tool in assessing ambulation capabilities of people with MS. PMID:23878746

  18. Cerebral palsy: Influence of TheraTogs ® on gait, posture and in functional performance

    Raquel Ehlert

    Full Text Available Abstract Introduction: For children with cerebral palsy, orthoses take an important role in improving posture, gait, functional performance and preventing secondary musculoskeletal disorders. Objective: To evaluate the influence of TheraTogs® on the posture, distribution of plantar pressure during gait and functional performance of a child with spastic diplegia cerebral palsy. Methods: A quantitative evaluation was carried out on a case study in which an 11-year-old child diagnosed with diplegic cerebral palsy underwent postural assessment through the Postural Assessment Software (PAS, plantar pressure distribution assessment during barefoot gait through the Emed-X system, before and after the intervention period of 8 weeks and functional assessment (Pediatric Evaluation of Disability Inventory - PEDI, with and without TheraTogs®. Results: In posture, TheraTogs® had greater influence on hip extension and this change was greater during its use. In the plantar pressure distribution assessment, an increase in posteriorization of plantar pressure occurred in the initial contact, the performance of the push-off phase and initial swing phase improved. In functionality, the child showed improvements in mobility, however, their self-care ability with TheraTogs® was reduced. Conclusion: Although improvements in posture, gait and functionality were verified with the use of TheraTogs®, the excessive heat, difficulties in toileting and self-care were disadvantages in wearing TheraTogs®.

  19. Orientation dependence of phase diagrams and physical properties in epitaxial Ba0.6Sr0.4TiO3 films

    Qiu, J. H.; Zhao, T. X.; Chen, Z. H.; Yuan, N. Y.; Ding, J. N.

    2018-04-01

    Orientation dependence of phase diagrams and physical properties of Ba0.6Sr0.4TiO3 films are investigated by using a phenomenological Landau-Devonshire theory. New ferroelectric phases, such as the tetragonal a1 phase and the orthorhombic a2 c phase in (110) oriented film and the monoclinic MA phase in (111) oriented film, appear in the "misfit strain-temperature" phase diagrams as compared with (001) oriented film. Moreover, the phase diagrams of (110) and (111) oriented films are more complex than that of (001) oriented film due to the nonlinear coupling terms appeared in the thermodynamic potential. The dielectric and piezoelectric properties largely depend on the misfit strain and orientation. (111) oriented film has the better piezoelectric property than (110) oriented film. Furthermore, the compressive misfit strain is prone to induce the larger piezoelectric property than tensile misfit strain.

  20. A method to simulate motor control strategies to recover from perturbations: application to a stumble recovery during gait.

    Forner-Cordero, Arturo; Ackermann, Marko; de Lima Freitas, Mateus

    2011-01-01

    Perturbations during human gait such as a trip or a slip can result in a fall, especially among frail populations such as the elderly. In order to recover from a trip or a stumble during gait, humans perform different types of recovery strategies. It is very useful to uncover the mechanisms of the recovery to improve training methods for populations at risk of falling. Moreover, human recovery strategies could be applied to implement controllers for bipedal robot walker, as an application of biomimetic design. A biomechanical model of the response to a trip during gait might uncover the control mechanisms underlying the different recovery strategies and the adaptation of the responses found during the execution of successive perturbation trials. This paper introduces a model of stumble in the multibody system framework. This model is used to assess different feedforward strategies to recover from a trip. First of all, normal gait patterns for the musculoskeletal system model are obtained by solving an optimal control problem. Secondly, the reference gait is perturbed by the application of forces on the swinging foot in different ways: as an instantaneous inelastic collision of the foot with an obstacle, as an impulsive horizontal force or using a force curve measured experimentally during gait perturbation experiments. The influence of the type of perturbation, the timing of the collision with respect to the gait cycle, as well as of the coefficient of restitution was investigated previously. Finally, in order to test the effects of different muscle excitation levels on the initial phases of the recovery response, several muscle excitations were added to selected muscles of the legs, thus providing a simulation of the recovery reactions. These results pave the way for future analysis and modeling of the control mechanisms of gait.

  1. Deterioration of gait and balance over time

    Kreisel, Stefan H; Blahak, Christian; Bäzner, Hansjörg

    2013-01-01

    Cross-sectional studies have shown an association between the severity of age-related white matter change (ARWMC) and lower body motor function. However, the association between prevalent ARWMC and incident deterioration of balance and gait remains insufficiently investigated. This study investig......Cross-sectional studies have shown an association between the severity of age-related white matter change (ARWMC) and lower body motor function. However, the association between prevalent ARWMC and incident deterioration of balance and gait remains insufficiently investigated. This study...... relevance: given the increasing use of neuroimaging, incidental white matter pathology is common; being able to delineate natural trajectories of balance and gait function given ARWMC may improve patient advice and help optimize allocation of care....

  2. Gait disorders in patients with fibromyalgia.

    Auvinet, Bernard; Bileckot, Richard; Alix, Anne-Sophie; Chaleil, Denis; Barrey, Eric

    2006-10-01

    The objective of this study was to compare gait in patients with fibromyalgia and in matched controls. Measurements must be obtained in patients with fibromyalgia, as the evaluation scales for this disorder are semi-quantitative. We used a patented gait analysis system (Locometrix Centaure Metrix, France) developed by the French National Institute for Agricultural Research. Relaxed walking was evaluated in 14 women (mean age 50+/-5 years; mean height 162+/-5 cm; and mean body weight 68+/-13 kg) meeting American College of Rheumatology criteria for fibromyalgia and in 14 controls matched on sex, age, height, and body weight. Gait during stable walking was severely altered in the patients. Walking speed was significantly diminished (Pfibromyalgia.

  3. Gait characteristics in women's safety shoes.

    Goto, Kanako; Abe, Kaoru

    2017-11-01

    Although workers in Japan are required to wear safety footwear, there is concern about occupational accidents that occur when wearing safety shoes. This study aimed to analyze the effect of wearing hardsoled safety shoes on both spatiotemporal gait characteristics and the muscle activity in the lower extremities. Seventeen young women participated in this study. A 5-m gait trial and a surface electromyography trial were conducted while the women walked in either safety shoes or sports shoes. Paired t-tests were performed to analyze the differences in gait characteristics when walking in the two different pairs of shoes. Walking in safety shoes was associated with a significant increase in vastus lateralis, biceps femoris and tibialis anterior activity. This increased muscle activity in the lower extremities is likely compensating for the lower flexibility of the safety shoes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. DeepGait: A Learning Deep Convolutional Representation for View-Invariant Gait Recognition Using Joint Bayesian

    Chao Li

    2017-02-01

    Full Text Available Human gait, as a soft biometric, helps to recognize people through their walking. To further improve the recognition performance, we propose a novel video sensor-based gait representation, DeepGait, using deep convolutional features and introduce Joint Bayesian to model view variance. DeepGait is generated by using a pre-trained “very deep” network “D-Net” (VGG-D without any fine-tuning. For non-view setting, DeepGait outperforms hand-crafted representations (e.g., Gait Energy Image, Frequency-Domain Feature and Gait Flow Image, etc.. Furthermore, for cross-view setting, 256-dimensional DeepGait after PCA significantly outperforms the state-of-the-art methods on the OU-ISR large population (OULP dataset. The OULP dataset, which includes 4007 subjects, makes our result reliable in a statistically reliable way.

  5. Quantitative Gait Measurement With Pulse-Doppler Radar for Passive In-Home Gait Assessment

    Wang, Fang; Skubic, Marjorie; Rantz, Marilyn; Cuddihy, Paul E.

    2014-01-01

    In this paper, we propose a pulse-Doppler radar system for in-home gait assessment of older adults. A methodology has been developed to extract gait parameters including walking speed and step time using Doppler radar. The gait parameters have been validated with a Vicon motion capture system in the lab with 13 participants and 158 test runs. The study revealed that for an optimal step recognition and walking speed estimation, a dual radar set up with one radar placed at foot level and the ot...

  6. Gross tumor volume dependency on phase sorting methods of four-dimensional computed tomography images for lung cancer

    Lee, Soo Yong; Lim, Sang Wook; Ma, Sun Young; Yu, Je Sang [Dept. of Radiation Oncology, Kosin University Gospel Hospital, Kosin University College of Medicine, Busan (Korea, Republic of)

    2017-09-15

    To see the gross tumor volume (GTV) dependency according to the phase selection and reconstruction methods, we measured and analyzed the changes of tumor volume and motion at each phase in 20 cases with lung cancer patients who underwent image-guided radiotherapy. We retrospectively analyzed four-dimensional computed tomography (4D-CT) images in 20 cases of 19 patients who underwent image-guided radiotherapy. The 4D-CT images were reconstructed by the maximum intensity projection (MIP) and the minimum intensity projection (Min-IP) method after sorting phase as 40%–60%, 30%–70%, and 0%–90%. We analyzed the relationship between the range of motion and the change of GTV according to the reconstruction method. The motion ranges of GTVs are statistically significant only for the tumor motion in craniocaudal direction. The discrepancies of GTV volume and motion between MIP and Min-IP increased rapidly as the wider ranges of duty cycles are selected. As narrow as possible duty cycle such as 40%–60% and MIP reconstruction was suitable for lung cancer if the respiration was stable. Selecting the reconstruction methods and duty cycle is important for small size and for large motion range tumors.

  7. Controlling patient participation during robot-assisted gait training

    2011-01-01

    Background The overall goal of this paper was to investigate approaches to controlling active participation in stroke patients during robot-assisted gait therapy. Although active physical participation during gait rehabilitation after stroke was shown to improve therapy outcome, some patients can behave passively during rehabilitation, not maximally benefiting from the gait training. Up to now, there has not been an effective method for forcing patient activity to the desired level that would most benefit stroke patients with a broad variety of cognitive and biomechanical impairments. Methods Patient activity was quantified in two ways: by heart rate (HR), a physiological parameter that reflected physical effort during body weight supported treadmill training, and by a weighted sum of the interaction torques (WIT) between robot and patient, recorded from hip and knee joints of both legs. We recorded data in three experiments, each with five stroke patients, and controlled HR and WIT to a desired temporal profile. Depending on the patient's cognitive capabilities, two different approaches were taken: either by allowing voluntary patient effort via visual instructions or by forcing the patient to vary physical effort by adapting the treadmill speed. Results We successfully controlled patient activity quantified by WIT and by HR to a desired level. The setup was thereby individually adaptable to the specific cognitive and biomechanical needs of each patient. Conclusion Based on the three successful approaches to controlling patient participation, we propose a metric which enables clinicians to select the best strategy for each patient, according to the patient's physical and cognitive capabilities. Our framework will enable therapists to challenge the patient to more activity by automatically controlling the patient effort to a desired level. We expect that the increase in activity will lead to improved rehabilitation outcome. PMID:21429200

  8. Periodic gaits for the CMU Ambler

    Dwivedi, Suren N.; Mahalingam, Swaminathan

    1992-02-01

    The configuration of the Carnegie-Mellon University Ambler, a six-legged autonomous walking vehicle for exploring Mars, enables the recovery of a trailing leg past the leading leg to reduce the energy expenditure in terrain interactions. In this article, gaits developed for this unprecedented configuration are described. A stability criterion has been developed that ensures stability of the vehicle in the event of failure of any one of the supporting legs. Periodic gaits developed for the Ambler utilize the Ambler's unique abilities and continuously satisfy the stability criterion.

  9. Person identification by gait analysis and photogrammetry

    Lynnerup, Niels; Vedel, Jens

    2005-01-01

    Surveillance images from a bank robbery were analyzed and compared with images of a suspect. Based on general bodily features, gait and anthropometric measurements, we were able to conclude that one of the perpetrators showed strong resemblance to the suspect. Both exhibited a gait characterized...... by hyperextension of the leg joints, and bodily measurements did not differ by more than 6 mm on average. The latter was quantified by photogrammetry: i.e., measuring by using images of the perpetrator as captured by surveillance cameras. Using the computer software Photomodeler Pro, synchronous images from...

  10. Implications of the bedform phase diagram for size-dependent changes of ooid cortical fabric

    Anderson, N. T.; Cowan, C. A.

    2017-12-01

    Preliminary petrographic and electron microprobe analyses of well-preserved concentric and radial-concentric ooids in Late Cambrian carbonates of the Port au Port Group, western Newfoundland, Canada, show no Sr enrichment indicative of an aragonite precursor for ooid cortices. Dissolution features such as elephantine ooids, spalled cortices, and dropped nuclei reported by other authors in these and equivalent carbonates elsewhere were not analyzed in this study. It is likely that the pristine concentric and radial-concentric ooids studied here were originally calcite and may exhibit a "banded-radial" fabric (sensu Medwedeff and Wilkinson 1983). Thus, the change in petrographic fabric does not correspond to a change in mineralogy in these ooids. Furthermore, ooids in these rocks and in previous studies of similar rocks exhibit a change from radial to concentric fabric at locally consistent diameters. These two observations suggest that hydrodynamic conditions are the causal mechanism for shifts in ooid cortical fabric. Previous workers have taken this size-dependent shift in cortical fabric to represent increased abrasion that occurs with the transition from suspended load to bedload transport, but disregard bedform stability. We note that at a given flow velocity and depth, ooid growth can trigger a shift from the ripple stability field to the dune stability field. Observations of the rate of migration of modern meter-scale ooid tidal dunes in the Bahamas can be used to constrain ooid transport, and suggest that ooids in these settings may be transported for only minutes to hours twice per year. Therefore, the duration of ooid "sleep" (the time spent buried within the dune) may be 105 greater in dunes compared to ripples. This prolonged subsurface residence time may be a heretofore unconsidered control on the development of ooid cortices. It may dictate radial vs. concentric fabric; drastically diminish abrasion; sequester ooids chemically (and biochemically) from

  11. Long-term gas migration modelling in compacted bentonite using swelling/shrinkage-dependent two phase flow parameters

    Tawara, Y.; Mori, K.; Tada, K.; Shimura, T.; Sato, S.; Yamamoto, S.; Asano, H.; Namiki, K.

    2012-01-01

    inconsistent with those obtained from the gas injection test data. This inconsistency cannot be interpreted by standard hysteresis effect only. Since the moisture conditions of specimens used in the hydration test and the gas injection test were considerably different, we interpreted that swelling and shrinkage of montmorillonite induced the deformation of macro-pores. In order to deal with these phenomena, we proposed a new modelling approach which makes it possible to consider the interaction between pore moisture and macro-pores deformation. It leads to the consistent evaluation of the long-term gas migration behaviors including not only the re-saturation phase but also the gas generation and migration phase. Such mechanical effects are incorporated into the existing TH coupled code 'GETFLOWS' by introducing the saturation-dependent multiple non-linear functions such as porosity, permeability, capillary pressure and so on. Examples of swelling/shrinkage-dependent two phase flow parameters are shown in Figure 1. The shapes of capillary pressure and relative permeability curve are updated by the amount of pore moisture. Furthermore, the pathway dilation is generalized in the same treatments by specifying the water saturation threshold for the development of pathway propagations. Our proposed model has been applied to both laboratory-scaled and field-scaled gas migration problems. In the laboratory-scaled problems, we have confirmed that measured test data can be successfully reproduced by the new modelling approach using consistent parameters. In the field-scaled problems, it has found that the mechanical effect of swelling/shrinkage induced deformation of macro-pores impacts the performance measure, and should be considered in the gas migration analysis. This study includes a part of the result of 'Development of the technique for the evaluation of long-term performance of EBS, FY2011' under a grant from the Japanese Ministry of Economy Trade and Industry. (authors)

  12. Listenmee and Listenmee smartphone application: synchronizing walking to rhythmic auditory cues to improve gait in Parkinson's disease.

    Lopez, William Omar Contreras; Higuera, Carlos Andres Escalante; Fonoff, Erich Talamoni; Souza, Carolina de Oliveira; Albicker, Ulrich; Martinez, Jairo Alberto Espinoza

    2014-10-01

    Evidence supports the use of rhythmic external auditory signals to improve gait in PD patients (Arias & Cudeiro, 2008; Kenyon & Thaut, 2000; McIntosh, Rice & Thaut, 1994; McIntosh et al., 1997; Morris, Iansek, & Matyas, 1994; Thaut, McIntosh, & Rice, 1997; Suteerawattananon, Morris, Etnyre, Jankovic, & Protas , 2004; Willems, Nieuwboer, Chavert, & Desloovere, 2006). However, few prototypes are available for daily use, and to our knowledge, none utilize a smartphone application allowing individualized sounds and cadence. Therefore, we analyzed the effects on gait of Listenmee®, an intelligent glasses system with a portable auditory device, and present its smartphone application, the Listenmee app®, offering over 100 different sounds and an adjustable metronome to individualize the cueing rate as well as its smartwatch with accelerometer to detect magnitude and direction of the proper acceleration, track calorie count, sleep patterns, steps count and daily distances. The present study included patients with idiopathic PD presented gait disturbances including freezing. Auditory rhythmic cues were delivered through Listenmee®. Performance was analyzed in a motion and gait analysis laboratory. The results revealed significant improvements in gait performance over three major dependent variables: walking speed in 38.1%, cadence in 28.1% and stride length in 44.5%. Our findings suggest that auditory cueing through Listenmee® may significantly enhance gait performance. Further studies are needed to elucidate the potential role and maximize the benefits of these portable devices. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Assessment of gait in toddlers with normal motor development and in hemiplegic children with mild motor impairment: a validity study

    Priscilla R. P. Figueiredo

    2013-08-01

    Full Text Available BACKGROUND: The optimization of gait performance is an important goal in the rehabilitation of children with cerebral palsy (CP who present a prognosis associated with locomotion. Gait analysis using videos captured by digital cameras requires validation. OBJECTIVE: To evaluate the validity of a method that involves the analysis of videos captured using a digital camera for quantifying the temporal parameters of gait in toddlers with normal motor development and children with CP. METHOD: Eleven toddlers with normal motor development and eight children with spastic hemiplegia who were able to walk without assistive devices were asked to walk through a space contained in the visual field of two instruments: a digital camera and a three-dimensional motion analysis system, Qualisys Pro-Reflex. The duration of the stance and swing phases of gait and of the entire gait cycle were calculated by analyzing videos captured by a digital camera and compared to those obtained by Qualisys Pro-Reflex, which is considered a highly accurate system. RESULTS: The Intraclass Correlation Coefficient (ICC demonstrated excellent agreement (ICC>0.90 between the two procedures for all measurements, except for the swing phase of the normal toddlers (ICC=0.35. The standard error of measurement was less than 0.02 seconds for all measures. CONCLUSIONS: The results reveal similarities between the two instruments, suggesting that digital cameras can be valid instruments for quantifying two temporal parameters of gait. This congruence is of clinical and scientific relevance and validates the use of digital cameras as a resource for helping the assessment and documentation of the therapeutic effects of interventions targeted at the gait of children with CP.

  14. The effects of high custom made shoes on gait characteristics and patient satisfaction in hemiplegic gait

    Eckhardt, Martine M.; Mulder, Mascha C. Borgerhoff; Horemans, Herwin L.; van der Woude, Luc H.; Ribbers, Gerard M.

    2011-01-01

    Objective: To determine the effects of a temporary high custom made orthopaedic shoe on functional mobility, walking speed, and gait characteristics in hemiplegic stroke patients. In addition, interference of attentional demands and patient satisfaction were studied. Design: Clinical experimental

  15. The effects of high custom made shoes on gait characteristics and patient satisfaction in hemiplegic gait

    Eckhardt, Martine M; Mulder, Mascha C Borgerhoff; Horemans, Herwin L; van der Woude, Lucas; Ribbers, Gerard M

    2011-01-01

    OBJECTIVE: To determine the effects of a temporary high custom made orthopaedic shoe on functional mobility, walking speed, and gait characteristics in hemiplegic stroke patients. In addition, interference of attentional demands and patient satisfaction were studied. DESIGN: Clinical experimental

  16. Robotic Pectoral Fin Thrust Vectoring Using Weighted Gait Combinations

    John S. Palmisano

    2012-01-01

    Full Text Available A method was devised to vector propulsion of a robotic pectoral fin by means of actively controlling fin surface curvature. Separate flapping fin gaits were designed to maximize thrust for each of three different thrust vectors: forward, reverse, and lift. By using weighted combinations of these three pre-determined main gaits, new intermediate hybrid gaits for any desired propulsion vector can be created with smooth transitioning between these gaits. This weighted gait combination (WGC method is applicable to other difficult-to-model actuators. Both 3D unsteady computational fluid dynamics (CFD and experimental results are presented.

  17. Effects of obesity and chronic low back pain on gait

    Cimolin, Veronica; Vismara, Luca; Galli, Manuela; Zaina, Fabio; Negrini, Stefano; Capodaglio, Paolo

    2011-01-01

    Abstract Background Obesity is often associated with low back pain (LBP). Despite empirical evidence that LBP induces gait abnormalities, there is a lack of quantitative analysis of the combined effect of obesity and LBP on gait. The aim of our study was to quantify the gait pattern of obese subjects with and without LBP and normal-mass controls by using Gait Analysis (GA), in order to investigate the cumulative effects of obesity and LBP on gait. Methods Eight obese females with chronic LBP ...

  18. Phase diagrams of a nonequilibrium mixed spin-1/2 and spin-2 Ising ferrimagnetic system under a time-dependent oscillating magnetic field

    Keskin, M.; Canko, O.; Gueldal, S.

    2009-01-01

    We present phase diagrams for a nonequilibrium mixed spin-1/2 and spin-2 Ising ferrimagnetic system on a square lattice in the presence of a time dependent oscillating external magnetic field. We employ the Glauber transition rates to construct the mean-field dynamical equations. The time variation of the average magnetizations and the thermal behavior of the dynamic magnetizations are investigated, extensively. The nature (continuous or discontinuous) of the transitions is characterized by studying the thermal behaviors of the dynamic magnetizations. The dynamic phase transition points are obtained and the phase diagrams are presented in two different planes. Phase diagrams contain paramagnetic (p) and ferrimagnetic (i) phases, and one coexistence or mixed phase region, namely the i+p, that strongly depend on interaction parameters. The system exhibits the dynamic tricritical point and the reentrant behaviors.

  19. Phase diagrams of a nonequilibrium mixed spin-1/2 and spin-2 Ising ferrimagnetic system under a time-dependent oscillating magnetic field

    Keskin, M., E-mail: keskin@erciyes.edu.t [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Canko, O. [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Gueldal, S. [Institute of Science, Erciyes University, 38039 Kayseri (Turkey)

    2009-12-14

    We present phase diagrams for a nonequilibrium mixed spin-1/2 and spin-2 Ising ferrimagnetic system on a square lattice in the presence of a time dependent oscillating external magnetic field. We employ the Glauber transition rates to construct the mean-field dynamical equations. The time variation of the average magnetizations and the thermal behavior of the dynamic magnetizations are investigated, extensively. The nature (continuous or discontinuous) of the transitions is characterized by studying the thermal behaviors of the dynamic magnetizations. The dynamic phase transition points are obtained and the phase diagrams are presented in two different planes. Phase diagrams contain paramagnetic (p) and ferrimagnetic (i) phases, and one coexistence or mixed phase region, namely the i+p, that strongly depend on interaction parameters. The system exhibits the dynamic tricritical point and the reentrant behaviors.

  20. The role of knee joint moments and knee impairments on self-reported knee pain during gait in patients with knee osteoarthritis.

    O'Connell, Megan; Farrokhi, Shawn; Fitzgerald, G Kelley

    2016-01-01

    The association between high mechanical knee joint loading during gait with onset and progression of knee osteoarthritis has been extensively studied. However, less attention has been given to risk factors related to increased pain during gait. The purpose of this study was to evaluate knee joint moments and clinical characteristics that may be associated with gait-related knee pain in patients with knee osteoarthritis. Sixty-seven participants with knee osteoarthritis were stratified into three groups of no pain (n=18), mild pain (n=27), or moderate/severe pain (n=22) based on their self-reported symptoms during gait. All participants underwent three-dimensional gait analysis. Quadriceps strength, knee extension range of motion, radiographic knee alignment and self-reported measures of global pain and function were also quantified. The moderate/severe pain group demonstrated worse global pain (Pknee flexion moments during the midstance phase of gait compared to the no pain group (P=0.02). Additionally, the moderate/severe pain group demonstrated greater varus knee malalignment (P=0.009), which was associated with higher weight acceptance peak knee adduction moments (P=0.003) and worse global pain (P=0.003) and physical function scores (P=0.006). Greater knee flexion moment is present during the midstance phase of gait in patients with knee osteoarthritis and moderate/severe pain during gait. Additionally, greater varus malalignment may be a sign of increased global knee joint dysfunction that can influence many activities of daily living beyond gait. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Real time biometric surveillance with gait recognition

    Mohapatra, Subasish; Swain, Anisha; Das, Manaswini; Mohanty, Subhadarshini

    2018-04-01

    Bio metric surveillance has become indispensable for every system in the recent years. The contribution of bio metric authentication, identification, and screening purposes are widely used in various domains for preventing unauthorized access. A large amount of data needs to be updated, segregated and safeguarded from malicious software and misuse. Bio metrics is the intrinsic characteristics of each individual. Recently fingerprints, iris, passwords, unique keys, and cards are commonly used for authentication purposes. These methods have various issues related to security and confidentiality. These systems are not yet automated to provide the safety and security. The gait recognition system is the alternative for overcoming the drawbacks of the recent bio metric based authentication systems. Gait recognition is newer as it hasn't been implemented in the real-world scenario so far. This is an un-intrusive system that requires no knowledge or co-operation of the subject. Gait is a unique behavioral characteristic of every human being which is hard to imitate. The walking style of an individual teamed with the orientation of joints in the skeletal structure and inclinations between them imparts the unique characteristic. A person can alter one's own external appearance but not skeletal structure. These are real-time, automatic systems that can even process low-resolution images and video frames. In this paper, we have proposed a gait recognition system and compared the performance with conventional bio metric identification systems.

  2. The Practicalities of Assessing Freezing of Gait

    Barthel, C.; Mallia, E.; Debu, B.; Bloem, B.R.; Ferraye, M.U.

    2016-01-01

    BACKGROUND: Freezing of gait (FOG) is a mysterious, complex and debilitating phenomenon in Parkinson's disease. Adequate assessment is a pre-requisite for managing FOG, as well as for assigning participants in FOG research. The episodic nature of FOG, as well as its multiple clinical expressions

  3. Proprioceptive perturbations of stability during gait

    Duysens, J.; Beerepoot, V.P.; Veltink, Petrus H.; Weerdesteyn, V.; Smits-Engelsman, B.C.M.

    2008-01-01

    Through recent studies, the role of proprioceptors in reactions to perturbations during gait has been finally somewhat better understood. The input from spindle afferents has been investigated with tendon taps, vibration and other forms of muscle stretches, including some resembling natural

  4. The effects of aquatic trunk exercise on gait and muscle activity in stroke patients: a randomized controlled pilot study.

    Park, Byoung-Sun; Noh, Ji-Woong; Kim, Mee-Young; Lee, Lim-Kyu; Yang, Seung-Min; Lee, Won-Deok; Shin, Yong-Sub; Kim, Ju-Hyun; Lee, Jeong-Uk; Kwak, Taek-Yong; Lee, Tae-Hyun; Kim, Ju-Young; Park, Jaehong; Kim, Junghwan

    2015-11-01

    [Purpose] The purpose of this study was to investigate the relationship between muscle activity and gait function following aquatic trunk exercise in hemiplegic stroke patients. [Subjects and Methods] This study's participants included thirteen hemiplegic patients (ten males and three females). The aquatic therapy consisted of administering concentrative aquatic therapy for four weeks in a therapeutic pool. Gait parameters were measured using a gait analysis system adjusted to each subject's comfortable walking speed. Electromyographic signals were measured for the rectus abdominis, external abdominal oblique, transversus abdominis/internal-abdominal oblique, and erector spine of each patients. [Results] The pre- and post-training performances of the transversus abdominis/internal-abdominal oblique were compared statistically. There was no statistical difference between the patients' pre- and post-training values of maximal voluntary isometric contraction of the rectus abdominis, but the external abdominal oblique values tended to improve. Furthermore, gait factors improved significantly in terms of walking speeds, walking cycles, affected-side stance phases, affected-stride lengths, and stance-phase symmetry indices, respectively. [Conclusion] These results suggest that the trunk exercise during aquatic therapy may in part contribute to clinically relevant improvements in muscle activities and gait parameters.

  5. Pulse-bandwidth dependence of coherent phase control of resonance-mediated (2+1) three-photon absorption

    Gandman, Andrey; Chuntonov, Lev; Rybak, Leonid; Amitay, Zohar

    2007-01-01

    We study in detail coherent phase control of femtosecond resonance-mediated (2+1) three-photon absorption and its dependence on the spectral bandwidth of the excitation pulse. The regime is the weak-field regime of third perturbative order. The corresponding interference mechanism involves a group of three-photon excitation pathways that are on resonance with the intermediate state and a group of three-photon excitation pathways that are near resonant with it. The model system of the study is atomic sodium (Na), for which experimental and numerical-theoretical results are obtained. Prominent among the results is our finding that with simple proper pulse shaping an increase in the excitation bandwidth leads to a corresponding increase in the enhancement of the three-photon absorption over the absorption induced by the (unshaped) transform-limited pulse. For example, here, a 40 nm bandwidth leads to an order-of-magnitude enhancement over the transform-limited absorption

  6. Temperature dependence of InN growth on (0001) sapphire substrates by atmospheric pressure hydride vapor phase epitaxy

    Kumagai, Yoshinao; Adachi, Hirokazu; Otake, Aya; Higashikawa, Yoshihiro; Togashi, Rie; Murakami, Hisashi; Koukitu, Akinori

    2010-01-01

    The temperature dependence of InN growth on (0001) sapphire substrates by atmospheric pressure hydride vapor phase epitaxy (HVPE) was investigated. N-polarity single-crystal InN layers were successfully grown at temperatures ranging from 400 to 500 C. The a and c lattice constants of InN layers grown at 450 C or below were slightly larger than those of InN layers grown above 450 C due to oxygen incorporation that also increased the carrier concentration. The optical absorption edge of the InN layer decreased from above 2.0 to 0.76 eV when the growth temperature was increased from 450 to 500 C. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. The effects of mirror therapy on the gait of subacute stroke patients: a randomized controlled trial.

    Ji, Sang Gu; Kim, Myoung Kwon

    2015-04-01

    To investigate the effect of mirror therapy on the gait of patients with subacute stroke. Randomized controlled experimental study. Outpatient rehabilitation hospital. Thirty-four patients with stroke were randomly assigned to two groups: a mirror therapy group (experimental) and a control group. The stroke patients in the experimental group underwent comprehensive rehabilitation therapy and mirror therapy for the lower limbs. The stroke patients in the control group underwent sham therapy and comprehensive rehabilitation therapy. Participants in both groups received therapy five days per week for four weeks. Temporospatial gait characteristics, such as single stance, stance phase, step length, stride, swing phase, velocity, and cadence, were assessed before and after the four weeks therapy period. A significant difference was observed in post-training gains for the single stance (10.32 SD 4.14 vs. 6.54 SD 3.23), step length (8.47 SD 4.12 vs. 4.83 SD 2.14), and stride length (17.03 SD 6.57 vs 10.54 SD 4.34) between the experimental group and the control group (p two groups on stance phase, swing phase, velocity, cadence, and step width (P > 0.05). We conclude that mirror therapy may be beneficial in improving the effects of stroke on gait ability. © The Author(s) 2014.

  8. Effects of conventional overground gait training and a gait trainer with partial body weight support on spatiotemporal gait parameters of patients after stroke

    Park, Byoung-Sun; Kim, Mee-Young; Lee, Lim-Kyu; Yang, Seung-Min; Lee, Won-Deok; Noh, Ji-Woong; Shin, Yong-Sub; Kim, Ju-Hyun; Lee, Jeong-Uk; Kwak, Taek-Yong; Lee, Tae-Hyun; Kim, Ju-Young; Kim, Junghwan

    2015-01-01

    [Purpose] The purpose of this study was to confirm the effects of both conventional overground gait training (CGT) and a gait trainer with partial body weight support (GTBWS) on spatiotemporal gait parameters of patients with hemiparesis following chronic stroke. [Subjects and Methods] Thirty stroke patients were alternately assigned to one of two treatment groups, and both groups underwent CGT and GTBWS. [Results] The functional ambulation classification on the affected side improved signifi...

  9. Temperature dependence of thermal properties of Ag8In14Sb55Te23 phase-change memory materials

    Jiao, Xinbing; Gan, Fuxi; Wei, Jingsong; Xiao, Mufei

    2009-01-01

    The dependence of thermal properties of Ag 8 In 14 Sb 55 Te 23 phase-change memory materials in crystalline and amorphous states on temperature was measured and analyzed. The results show that in the crystalline state, the thermal properties monotonically decrease with the temperature and present obvious crystalline semiconductor characteristics. The heat capacity, thermal diffusivity, and thermal conductivity decrease from 0.35 J/gK, 1.85 mm 2 /s, and 4.0 W/mK at 300 K to 0.025 J/gK, 1.475 mm 2 /s, and 0.25 W/mK at 600 K, respectively. In the amorphous state, while the dependence of thermal properties on temperature does not present significant changes, the materials retain the glass-like thermal characteristics. Within the temperature range from 320 K to 440 K, the heat capacity fluctuates between 0.27 J/gK and 0.075 J/gK, the thermal diffusivity basically maintains at 0.525 mm 2 /s, and the thermal conductivity decreases from 1.02 W/mK at 320 K to 0.2 W/mK at 440 K. Whether in the crystalline or amorphous state, Ag 8 In 14 Sb 55 Te 23 are more thermally active than Ge 2 Sb 2 Te 5 , that is, the Ag 8 In 14 Sb 55 Te 23 composites bear stronger thermal conduction and diffusion than the Ge 2 Sb 2 Te 5 phase-change memory materials. (orig.)

  10. Trade-offs between microbial growth phases lead to frequency-dependent and non-transitive selection.

    Manhart, Michael; Adkar, Bharat V; Shakhnovich, Eugene I

    2018-02-14

    Mutations in a microbial population can increase the frequency of a genotype not only by increasing its exponential growth rate, but also by decreasing its lag time or adjusting the yield (resource efficiency). The contribution of multiple life-history traits to selection is a critical question for evolutionary biology as we seek to predict the evolutionary fates of mutations. Here we use a model of microbial growth to show that there are two distinct components of selection corresponding to the growth and lag phases, while the yield modulates their relative importance. The model predicts rich population dynamics when there are trade-offs between phases: multiple strains can coexist or exhibit bistability due to frequency-dependent selection, and strains can engage in rock-paper-scissors interactions due to non-transitive selection. We characterize the environmental conditions and patterns of traits necessary to realize these phenomena, which we show to be readily accessible to experiments. Our results provide a theoretical framework for analysing high-throughput measurements of microbial growth traits, especially interpreting the pleiotropy and correlations between traits across mutants. This work also highlights the need for more comprehensive measurements of selection in simple microbial systems, where the concept of an ordinary fitness landscape breaks down. © 2018 The Author(s).

  11. Microencapsulated Phase Change Materials in Solar-Thermal Conversion Systems: Understanding Geometry-Dependent Heating Efficiency and System Reliability.

    Zheng, Zhaoliang; Chang, Zhuo; Xu, Guang-Kui; McBride, Fiona; Ho, Alexandra; Zhuola, Zhuola; Michailidis, Marios; Li, Wei; Raval, Rasmita; Akhtar, Riaz; Shchukin, Dmitry

    2017-01-24

    The performance of solar-thermal conversion systems can be improved by incorporation of nanocarbon-stabilized microencapsulated phase change materials (MPCMs). The geometry of MPCMs in the microcapsules plays an important role for improving their heating efficiency and reliability. Yet few efforts have been made to critically examine the formation mechanism of different geometries and their effect on MPCMs-shell interaction. Herein, through changing the cooling rate of original emulsions, we acquire MPCMs within the nanocarbon microcapsules with a hollow structure of MPCMs (h-MPCMs) or solid PCM core particles (s-MPCMs). X-ray photoelectron spectroscopy and atomic force microscopy reveals that the capsule shell of the h-MPCMs is enriched with nanocarbons and has a greater MPCMs-shell interaction compared to s-MPCMs. This results in the h-MPCMs being more stable and having greater heat diffusivity within and above the phase transition range than the s-MPCMs do. The geometry-dependent heating efficiency and system stability may have important and general implications for the fundamental understanding of microencapsulation and wider breadth of heating generating systems.

  12. Gait analysis in anorexia and bulimia nervosa.

    Cimolin, Veronica; Galli, Manuela; Vismara, Luca; Vimercati, Sara Laura; Precilios, Helmer; Cattani, Laila; Fabris De Souza, Shirley; Petroni, Maria Letizia; Capodaglio, Paolo

    2013-09-13

    Anorexia (AN) and Bulimia Nervosa (BN) are two common eating disorders, which appear to share some reduced motor capacities, such as a reduced balance. The presence and the extent of other motor disorders have not been investigated in a comprehensive way. The aim of this study was to quantify gait pattern in AN and BN individuals in order to ascertain possible differences from the normality range and provide novel data for developing some evidence-based rehabilitation strategies. Nineteen AN patients (age 30.16+9.73) and 20 BN patients (age 26.8+8.41) were assessed with quantitative 3D computerized Gait Analysis. Results were compared with a group of healthy controls (CG; 30.7+5.6). AN and BN patients were characterized by different gait strategies compared to CG. Spatio-temporal parameters indicated shorter step length, with AN showing the shortest values. AN walked slower than BN and CG. As for kinematics, AN and BN showed a nonphysiologic pattern at pelvis and hip level on the sagittal and frontal plane, with BN yielding the most abnormal values. Both AN and BN patients were characterized by high ankle plantar flexion capacity at toe-off when compared to CG. As for ankle kinetics, both AN and BN showed physiologic patterns. Stiffness at hip level was close to CG in both pathologic groups; at the ankle level, stiffness was significantly decreased in both groups, with AN displaying lower values. Both AN and BN were characterized by an altered gait pattern compared to CG. Biomechanical differences were evident mainly at pelvis and hip level. Loss of lean mass may lead to musculoskeletal adaptation, ultimately causing alterations in the gait pattern.

  13. A novel approach to gait synchronization and transition for reconfigurable walking platforms

    Shunsuke Nansai

    2015-04-01

    Full Text Available Legged robots based on one degree-of-freedom reconfigurable planar leg mechanisms, that are capable of generating multiple useful gaits, are highly desired due to the possibility of handling environments and tasks of high complexity while maintaining simple control schemes. An essential consideration in these reconfigurable legged robots is to attain stability in motion, at rest as well as while transforming from one configuration to another with the minimum number of legs as long as the full range of their walking patterns, resulting from the different gait cycles of their legs, is achieved. To this end, in this paper, we present a method for the generation of input joint trajectories to properly synchronize the movement of quadruped robots with reconfigurable legs. The approach is exemplified in a four-legged robot with reconfigurable Jansen legs capable of generating up to six useful different gait cycles. The proposed technique is validated through simulated results that show the platform׳s stability across its six feasible walking patterns and during gait transition phases, thus considerably extending the capabilities of the non-reconfigurable design.

  14. The Role of Proprioception in the Sagittal Setting of Anticipatory Postural Adjustments During Gait Initiation

    Pereira Marcelo P.

    2015-12-01

    Full Text Available Purpose. Previous studies have studied the role of proprioception on the setting of anticipatory postural adjustments (APA during gait initiation. However, these studies did not investigate the role of proprioception in the sagittal APA setting. We aimed to investigate the role of proprioception manipulation to induce APA sagittal adaptations on gait initiation. Methods. Fourteen healthy adults performed gait initiation without, and with, vibration applied before movement onset, and during movement. In addition, the effects of two different vibration frequencies (80 and 120Hz were tested. Vibration was applied bilaterally on the tibialis anterior, rectus femoris and trapezius superior. The first step characteristics, ground reaction forces and CoP behaviour were assessed. Results. Vibration improved gait initiation performance regardless of the moment it was applied. CoP velocity during the initial phase of APA was increased by vibration only when it was applied before movement. When vibration was applied to disturb the movement, no effects on the CoP behaviour were observed. Manipulation of vibration frequency had no effects. Conclusions. Rather than proprioception manipulation, the results suggest that post-vibratory effects and attentional mechanisms were responsible for our results. Taken together, the results show that sagittal APA setting is robust to proprioception manipulation.

  15. Differences in center of pressure trajectory between normal and steppage gait

    Jamshidi, Nima; Rostami, Mostafa; Najarian, Siamak; Menhaj, Mohammad Bagher; Saadatnia, Mohammad; Salami, Firooz

    2010-01-01

    BACKGROUND: This pilot study aimed to assess the differences in center of pressure trajectory in neuropathic patients with steppage gait. Steppage gait has previously been evaluated by several biomechanical methods, but plantar pressure distribution has been much less studied. The purpose of this study was to analyze the changes in center of pressure trajectory using a force plate. METHODS: The steppage gait group was selected from the patients using drop foot brace (25 male) and the control group was selected from Isfahan university students (20 male). They walked at self- selected speed at a mean of ten trials (+2) to collect the center of pressure using a force plate. Center of pressure patterns were categorized into four patterns based on the center of pressure displacement magnitude (spatial features) through time (temporal features) when the longitudinal axis of the insole was plotted as the Y- axis and the transverse axis of the insole as X- axis during stance phase. RESULTS: The horizontal angle measured from center of pressure linear regression was positive in the control group (4.6 ± 2.4) (p < 0.005), but negative in the patient group (- 2.3 ± 1.6) (p < 0.005). CONCLUSIONS: The finding of this research measured center of pressure trajectory in steppage gait over time, which is useful for designing better shoe sole and also orthopaedic device and better understanding of stability in patients with drop foot. PMID:21526056

  16. Differences in center of pressure trajectory between normal and steppage gait

    Nima Jamshidi

    2010-01-01

    Full Text Available Background: This pilot study aimed to assess the differences in center of pressure trajectory in neuropathic patients with steppage gait. Steppage gait has previously been evaluated by several biomechanical methods, but plantar pressure distribution has been much less studied. The purpose of this study was to analyze the changes in center of pressure tra-jectory using a force plate. Methods: The steppage gait group was selected from the patients using drop foot brace (25 male and the control group was selected from Isfahan university students (20 male. They walked at self- selected speed at a mean of ten tri-als (+2 to collect the center of pressure using a force plate. Center of pressure patterns were categorized into four pat-terns based on the center of pressure displacement magnitude (spatial features through time (temporal features when the longitudinal axis of the insole was plotted as the Y- axis and the transverse axis of the insole as X- axis during stance phase. Results: The horizontal angle measured from center of pressure linear regression was positive in the control group (4.6 ± 2.4 (p < 0.005, but negative in the patient group (- 2.3 ± 1.6 (p < 0.005. Conclusions: The finding of this research measured center of pressure trajectory in steppage gait over time, which is useful for designing better shoe sole and also orthopaedic device and better understanding of stability in patients with drop foot.

  17. Automated Gait Analysis Through Hues and Areas (AGATHA): a method to characterize the spatiotemporal pattern of rat gait

    Kloefkorn, Heidi E.; Pettengill, Travis R.; Turner, Sara M. F.; Streeter, Kristi A.; Gonzalez-Rothi, Elisa J.; Fuller, David D.; Allen, Kyle D.

    2016-01-01

    While rodent gait analysis can quantify the behavioral consequences of disease, significant methodological differences exist between analysis platforms and little validation has been performed to understand or mitigate these sources of variance. By providing the algorithms used to quantify gait, open-source gait analysis software can be validated and used to explore methodological differences. Our group is introducing, for the first time, a fully-automated, open-source method for the characterization of rodent spatiotemporal gait patterns, termed Automated Gait Analysis Through Hues and Areas (AGATHA). This study describes how AGATHA identifies gait events, validates AGATHA relative to manual digitization methods, and utilizes AGATHA to detect gait compensations in orthopaedic and spinal cord injury models. To validate AGATHA against manual digitization, results from videos of rodent gait, recorded at 1000 frames per second (fps), were compared. To assess one common source of variance (the effects of video frame rate), these 1000 fps videos were re-sampled to mimic several lower fps and compared again. While spatial variables were indistinguishable between AGATHA and manual digitization, low video frame rates resulted in temporal errors for both methods. At frame rates over 125 fps, AGATHA achieved a comparable accuracy and precision to manual digitization for all gait variables. Moreover, AGATHA detected unique gait changes in each injury model. These data demonstrate AGATHA is an accurate and precise platform for the analysis of rodent spatiotemporal gait patterns. PMID:27554674

  18. Phase transformation in multiferroic Bi5Ti3FeO15 ceramics by temperature-dependent ellipsometric and Raman spectra: An interband electronic transition evidence

    Jiang, P. P.; Duan, Z. H.; Xu, L. P.; Zhang, X. L.; Li, Y. W.; Hu, Z. G.; Chu, J. H.

    2014-02-01

    Thermal evolution and an intermediate phase between ferroelectric orthorhombic and paraelectric tetragonal phase of multiferroic Bi5Ti3FeO15 ceramic have been investigated by temperature-dependent spectroscopic ellipsometry and Raman scattering. Dielectric functions and interband transitions extracted from the standard critical-point model show two dramatic anomalies in the temperature range of 200-873 K. It was found that the anomalous temperature dependence of electronic transition energies and Raman mode frequencies around 800 K can be ascribed to intermediate phase transformation. Moreover, the disappearance of electronic transition around 3 eV at 590 K is associated with the conductive property.

  19. [Posture and gait disorders and the incidence of falling in patients with Parkinson].

    Cano-de la Cuerda, R; Macías-Jiménez, A I; Cuadrado-Pérez, M L; Miangolarra-Page, J C; Morales-Cabezas, M

    Although falls are one of the main causes of morbidity and mortality in patients with Parkinson's disease, studies about its incidence and predicting factors are scarce. Our study involved 25 patients with PD (15 males and 10 females; age: 75.8 +/- 6.5 years). A closed survey was used to determine a retrospective record of falls during the last year. An analysis was performed to examine whether there was a relationship with Hoehn and Yahr staging, the score on the Up and Go scale or the Barthel index and with possible risk factors for falls. All the patients had suffered falls at some time over the last year (mean number of falls: 6.5 +/- 3.8). 56% of the falls happened during the phases of the day when patient mobility was at its highest. A significant correlation was found between the number of falls and the Hoehn and Yahr and the Up and Go scores. The number of falls was significantly higher in patients with loss of postural reflexes, the need for help in order to walk, and blockage and festination phenomena. No association was found with fear of falling, visual alterations or postural lateralisation. Association with the Barthel index and dependence for activities of daily living reached almost significant levels. Postural instability and disorders affecting gait appear to be the factors that give patients with PD a greater propensity to fall. Patients who present such alterations should be submitted to rehabilitation therapy aimed at preventing them from falling.

  20. The coefficient of friction in Parkinson's disease gait.

    Kleiner, Ana; Galli, M; Franceschini, M; De Pandis, M F; Stocchi, F; Albertini, G; de Barros, Ricardo Machado Leite

    This study aimed to characterize the coefficient of friction (COF) curves of patients with Parkinson's disease (PD) during barefoot gait and to evaluate the relationships between this variable and functional scales. Twenty-two subjects with PD (ON phase of levodopa) and 22 healthy subjects participated in this study. The participants walked barefoot along a pathway that went over two force plates embedded in the floor of the data collection room. The instantaneous COF was calculated as the ratio between the horizontal and vertical components of the ground reaction forces. Two-sample t-tests applied to every 1% of the support phase of the COF curve were used to compare the groups and to identify the phases in which the two groups were different. Specifically, three COF areas were computed: Area 1 (for the loading response phase), Area 2 (for the midstance phase) and Area 3 (for the terminal stance phase). Pearson's tests were applied to assess the associations between the COF curve areas and the clinical scales. The subjects with PD exhibited lower COF values during the loading response and terminal stance phases and higher COF values during the mid-stance phase compared with the control group. A strong positive correlation was observed between Area 1 and the Timed Up and Go Test (90.3%). In conclusion, the patients' COFs exhibited patterns that were different from those of the control group. Moreover, during the loading response phase, these differences were well-correlated with the Timed Up and Go Test scale data; Timed Up and Go Test data can be used to identify the risk of falls among PD patients.

  1. IL-4 receptor-alpha-dependent control of Cryptococcus neoformans in the early phase of pulmonary infection.

    Andreas Grahnert

    Full Text Available Cryptococcus neoformans is an opportunistic fungal pathogen that causes lung inflammation and meningoencephalitis in immunocompromised people. Previously we showed that mice succumb to intranasal infection by induction of pulmonary interleukin (IL-4Rα-dependent type 2 immune responses, whereas IL-12-dependent type 1 responses confer resistance. In the experiments presented here, IL-4Rα⁻/⁻ mice unexpectedly show decreased fungal control early upon infection with C. neoformans, whereas wild-type mice are able to control fungal growth accompanied by enhanced macrophage and dendritic cell recruitment to the site of infection. Lower pulmonary recruitment of macrophages and dendritic cells in IL-4Rα⁻/⁻ mice is associated with reduced pulmonary expression of CCL2 and CCL20 chemokines. Moreover, IFN-γ and nitric oxide production are diminished in IL-4Rα⁻/⁻ mice compared to wild-type mice. To directly study the potential mechanism(s responsible for reduced production of IFN-γ, conventional dendritic cells were stimulated with C. neoformans in the presence of IL-4 which results in increased IL-12 production and reduced IL-10 production. Together, a beneficial role of early IL-4Rα signaling is demonstrated in pulmonary cryptococcosis, which contrasts with the well-known IL-4Rα-mediated detrimental effects in the late phase.

  2. Combination of robot-assisted and conventional body-weight-supported treadmill training improves gait in persons with multiple sclerosis: a pilot study.

    Ruiz, Jennifer; Labas, Michele P; Triche, Elizabeth W; Lo, Albert C

    2013-12-01

    The majority of persons with multiple sclerosis (MS) experience problems with gait, which they characterize as highly disabling impairments that adversely impact their quality of life. Thus, it is crucial to develop effective therapies to improve mobility for these individuals. The purpose of this study was to determine whether combination gait training, using robot-assisted treadmill training followed by conventional body-weight-supported treadmill training within the same session, improved gait and balance in individuals with MS. This study tested combination gait training in 7 persons with MS. The participants were randomized into the immediate therapy group (IT group) or the delayed therapy group (DT group). In phase I of the trial, the IT group received treatment while the DT group served as a concurrent comparison group. In phase II of the trial, the DT group received treatment identical to the treatment received by the IT group in phase I. Outcome measures included the 6-Minute Walk Test (6MWT), the Timed 25-Foot Walk Test, velocity, cadence, and the Functional Reach Test (FRT). Nonparametric statistical techniques were used for analysis. Combination gait training resulted in significantly greater improvements in the 6MWT for the IT group (median change = +59 m) compared with Phase I DT group (median change = -8 m) (P = 0.08) and FRT (median change = +3.3 cm in IT vs -0.8 cm in the DT group phase I; P = 0.03). Significant overall pre-post improvements following combination gait training were found in 6MWT (+32 m; P = 0.02) and FRT (+3.3 cm; P = 0.06) for IT and Phase II DT groups combined. Combination of robot with body-weight-supported treadmill training gait training is feasible and improved 6MWT and FRT distances in persons with MS.Video Abstract available (see Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A62) for more insights from the authors.

  3. The flexion synergy, mother of all synergies and father of new models of gait

    Jacques eDuysens

    2013-03-01

    Full Text Available Recently there has been a growing interest in the modular organization of leg movements, in particular those related to locomotion. One of the basic modules involves the flexion of the leg during swing and it was shown that this module is already present in neonates (Dominici, et al. 2011. In this paper, we question how these finding build upon the original work by Sherrington, who proposed that the flexor reflex is the basic building block of the flexion during swing phase. Similarly, the relation between the flexor reflex and the withdrawal reflex modules of Schouenborg et al. (1994 will be discussed. It will be argued that there is large overlap between these notions on modules and the older concepts of reflexes. In addition, it will be shown that there is a great flexibility in the expression of some of these modules during gait, thereby allowing for a phase-dependent modulation of the appropriate responses. In particular, the end of the stance phase is a period when the flexor synergy is facilitated. It is proposed that this is linked to the activation of circuitry that is responsible for the generation of locomotor patterns (CPG, central pattern generator. More specifically, it is suggested that the responses in that period relate to the activation of a flexor burst generator. The latter structure forms the core of a new asymmetric model of the CPG. This activation is controlled by afferent input (facilitation by a broad range of afferents, suppression by load afferent input. Meanwhile, many of these physiologic features have found their way in the control of very flexible walking bipedal robots.

  4. Isotope effects and the temperature dependences of the hyperfine coupling constants of muoniated sec-butyl radicals in condensed phases.

    Fleming, Donald G; Bridges, Michael D; Arseneau, Donald J; Chen, Ya Kun; Wang, Yan Alexander

    2011-04-07

    Reported here is the first μSR study of the muon (A(μ)) and proton (A(p)) β-hyperfine coupling constants (Hfcc) of muoniated sec-butyl radicals, formed by muonium (Mu) addition to 1-butene and to cis- and trans-2-butene. The data are compared with in vacuo spin-unrestricted MP2 and hybrid DFT/B3YLP calculations reported in the previous paper (I), which played an important part in the interpretation of the data. The T-dependences of both the (reduced) muon, A(μ)′(T), and proton, A(p)(T), Hfcc are surprisingly well explained by a simple model, in which the calculated Hfcc from paper I at energy minima of 0 and near ±120° are thermally averaged, assuming an energy dependence given by a basic 2-fold torsional potential. Fitted torsional barriers to A(μ)′(T) from this model are similar (~3 kJ/mol) for all muoniated butyl radicals, suggesting that these are dominated by ZPE effects arising from the C−Mu bond, but for A(p)(T) exhibit wide variations depending on environment. For the cis- and trans-2-butyl radicals formed from 2-butene, A(μ)′(T) exhibits clear discontinuities at bulk butene melting points, evidence for molecular interactions enhancing these muon Hfcc in the environment of the solid state, similar to that found in earlier reports for muoniated tert-butyl. In contrast, for Mu−sec-butyl formed from 1-butene, there is no such discontinuity. The muon hfcc for the trans-2-butyl radical are seemingly very well predicted by B3LYP calculations in the solid phase, but for sec-butyl from 1-butene, showing the absence of further interactions, much better agreement is found with the MP2 calculations across the whole temperature range. Examples of large proton Hfcc near 0 K are also reported, due to eclipsed C−H bonds, in like manner to C−Mu, which then also exhibit clear discontinuities in A(p)(T) at bulk melting points. The data suggest that the good agreement found between theory and experiment from the B3LYP calculations for eclipsed bonds in

  5. Mechanical Information of Plantar Fascia during Normal Gait

    Gu, Yaodong; Li, Zhiyong

    The plantar fascia is an important foot tissue in stabilizing the longitudinal arch of human foot. Direct measurement to monitor the mechanical situation of plantar fascia at human locomotion is difficult. The purpose of this study was to construct a three-dimensional finite element model of the foot to calculate the internal stress/strain value of plantar fascia during different stage of gait. The simulated stress distribution of plantar fascia was the lowest at heel-strike, which concentrated on the medial side of calcaneal tubercle. The peak stress of plantar fascia was appeared at push-off, and the value is more than 5 times of the heel-strike position. Current FE model was able to explore the plantar fascia tension trend at the main sub-phases of foot. More detailed fascia model and intrinsic muscle forces could be developed in the further study.

  6. Gait and Cognition in Parkinson’s Disease: Cognitive Impairment Is Inadequately Reflected by Gait Performance during Dual Task

    Heiko Gaßner

    2017-10-01

    Full Text Available IntroductionCognitive and gait deficits are common symptoms in Parkinson’s disease (PD. Motor-cognitive dual tasks (DTs are used to explore the interplay between gait and cognition. However, it is unclear if DT gait performance is indicative for cognitive impairment. Therefore, the aim of this study was to investigate if cognitive deficits are reflected by DT costs of spatiotemporal gait parameters.MethodsCognitive function, single task (ST and DT gait performance were investigated in 67 PD patients. Cognition was assessed by the Montreal Cognitive Assessment (MoCA followed by a standardized, sensor-based gait test and the identical gait test while subtracting serial 3’s. Cognitive impairment was defined by a MoCA score <26. DT costs in gait parameters [(DT − ST/ST × 100] were calculated as a measure of DT effect on gait. Correlation analysis was used to evaluate the association between MoCA performance and gait parameters. In a linear regression model, DT gait costs and clinical confounders (age, gender, disease duration, motor impairment, medication, and depression were correlated to cognitive performance. In a subgroup analysis, we compared matched groups of cognitively impaired and unimpaired PD patients regarding differences in ST, DT, and DT gait costs.ResultsCorrelation analysis revealed weak correlations between MoCA score and DT costs of gait parameters (r/rSp ≤ 0.3. DT costs of stride length, swing time variability, and maximum toe clearance (|r/rSp| > 0.2 were included in a regression analysis. The parameters only explain 8% of the cognitive variance. In combination with clinical confounders, regression analysis showed that these gait parameters explained 30% of MoCA performance. Group comparison revealed strong DT effects within both groups (large effect sizes, but significant between-group effects in DT gait costs were not observed.ConclusionThese findings suggest that DT gait performance is not indicative

  7. Experimental Evidence on the Dependence of the Standard GPS Phase Scintillation Index on the Ionospheric Plasma Drift Around Noon Sector of the Polar Ionosphere

    Wang, Y.; Zhang, Q.-H.; Jayachandran, P. T.; Moen, J.; Xing, Z.-Y.; Chadwick, R.; Ma, Y.-Z.; Ruohoniemi, J. M.; Lester, M.

    2018-03-01

    First experimental proof of a clear and strong dependence of the standard phase scintillation index (σφ) derived using Global Positioning System measurements on the ionospheric plasma flow around the noon sector of polar ionosphere is presented. σφ shows a strong linear dependence on the plasma drift speed measured by the Super Dual Auroral Radar Network radars, whereas the amplitude scintillation index (S4) does not. This observed dependence can be explained as a consequence of Fresnel frequency dependence of the relative drift and the used constant cutoff frequency (0.1 Hz) to detrend the data for obtaining standard σφ. The lack of dependence of S4 on the drift speed possibly eliminates the plasma instability mechanism(s) involved as a cause of the dependence. These observations further confirm that the standard phase scintillation index is much more sensitive to plasma flow; therefore, utmost care must be taken when identifying phase scintillation (diffractive phase variations) from refractive (deterministic) phase variations, especially in the polar region where the ionospheric plasma drift is much larger than in equatorial and midlatitude regions.

  8. THE ENERGY DEPENDENCE OF THE CENTROID FREQUENCY AND PHASE LAG OF THE QUASI-PERIODIC OSCILLATIONS IN GRS 1915+105

    Qu, J. L.; Lu, F. J.; Lu, Y.; Song, L. M.; Zhang, S.; Wang, J. M.; Ding, G. Q.

    2010-01-01

    We present a study of the centroid frequencies and phase lags of quasi-periodic oscillations (QPOs) as functions of photon energy for GRS 1915+105. It is found that the centroid frequencies of the 0.5-10 Hz QPOs and their phase lags are both energy dependent, and there exists an anticorrelation between the QPO frequency and phase lag. These new results challenge the popular QPO models, because none of them can fully explain the observed properties. We suggest that the observed QPO phase lags are partially due to the variation of the QPO frequency with energy, especially for those with frequency higher than 3.5 Hz.

  9. Evaluation of gait performance of knee osteoarthritis patients after total knee arthroplasty with different assistive devices

    Tereso,Ana; Martins,Maria Manuel; Santos,Cristina Peixoto

    2015-01-01

    IntroductionNowadays Knee Osteoarthritis (KOA) affects a large percentage of the elderly, and one solution is to perform a Total Knee Arthroplasty (TKA). In this paper, one intends to study the gait and posture of these patients after the TKA, while walking with three assistive devices (ADs) (crutches, standard walker (SW) and rollator with forearm supports (RFS)).MethodsEleven patients were evaluated in 2 phases: 5 days and 15 days after surgery. This evaluation was conducted with two inerti...

  10. Impaired transmission in the corticospinal tract and gait disability in spinal cord injured persons

    Barthélemy, Dorothy; Willerslev-Olsen, Maria; Lundell, Henrik

    2010-01-01

    with the degree of foot drop, as measured by toe elevation and ankle angle excursion in the first part of swing. Transcranial magnetic stimulation (TMS) was used to elicit motor evoked potentials (MEPs) in the TA. The amplitude of the MEPs at rest and their latency during contraction were correlated to the degree...... that transmission in the corticospinal tract is of importance for lifting the foot during the swing phase of human gait....

  11. Identification of Characteristic Motor Patterns Preceding Freezing of Gait in Parkinson’s Disease Using Wearable Sensors

    Luca Palmerini

    2017-08-01

    Full Text Available Freezing of gait (FOG is a disabling symptom that is common among patients with advanced Parkinson’s disease (PD. External cues such as rhythmic auditory stimulation can help PD patients experiencing freezing to resume walking. Wearable systems for automatic freezing detection have been recently developed. However, these systems detect a FOG episode after it has happened. Instead, in this study, a new approach for the prediction of FOG (before it actually happens is presented. Prediction of FOG might enable preventive cueing, reducing the likelihood that FOG will occur. Moreover, understanding the causes and circumstances of FOG is still an open research problem. Hence, a quantitative characterization of movement patterns just before FOG (the pre-FOG phase is of great importance. In this study, wearable inertial sensors were used to identify and quantify the characteristics of gait during the pre-FOG phase and compare them with the characteristics of gait that do not precede FOG. The hypothesis of this study is based on the threshold-based model of FOG, which suggests that before FOG occurs, there is a degradation of the gait pattern. Eleven PD subjects were analyzed. Six features extracted from movement signals recorded by inertial sensors showed significant differences between gait and pre-FOG. A classification algorithm was developed in order to test if it is feasible to predict FOG (i.e., detect it before it happens. The aim of the classification procedure was to identify the pre-FOG phase. Results confirm that there is a degradation of gait occurring before freezing. Results also provide preliminary evidence on the feasibility of creating an automatic algorithm to predict FOG. Although some limitations are present, this study shows promising findings for characterizing and identifying pre-FOG patterns, another step toward a better understanding, prediction, and prevention of this disabling symptom.

  12. Effect of electrical stimulation of hamstrings and L3/4 dermatome on gait in spinal cord injury

    van der Salm, Arjan; Veltink, Petrus H.; Hermens, Hermanus J.; Nene, A.V.; IJzerman, Maarten Joost

    2006-01-01

    Objective. To determine the effect of electrical stimulation of hamstrings and L3/4 dermatome on the swing phase of gait. Materials and Methods. Five subjects with incomplete spinal cord injury (SCI) with spasticity were included. Two electrical stimulation methods were investigated, i.e.,

  13. Gait performance of children and adolescents with sensorineural hearing loss.

    Melo, Renato de Souza

    2017-09-01

    Several studies have demonstrated that children with sensorineural hearing loss (SNHL) may exhibit balance disorders, which can compromise the gait performance of this population. Compare the gait performance of normal hearing (NH) children and those with SNHL, considering the sex and age range of the sample, and analyze gait performance according to degrees of hearing loss and etiological factors in the latter group. This is a cross-sectional study that assessed 96 students, 48 NH and 48 with SNHL, aged between 7 and 18 years. The Brazilian version of the Dynamic Gait Index (DGI) was used to analyze gait and the Mann-Whitney test for statistical analysis. The group with SNHL obtained lower average gait performance compared to NH subjects (p=0.000). This was also observed when the children were grouped by sex female and male (p=0.000). The same difference occurred when the children were stratified by age group: 7-18 years (p=0.000). The group with severe and profound hearing loss exhibited worse gait performance than those with mild and moderate loss (p=0.048) and children with prematurity as an etiological factor demonstrated the worst gait performance. The children with SNHL showed worse gait performance compared to NH of the same sex and age group. Those with severe and profound hearing loss and prematurity as an etiological factor demonstrated the worst gait performances. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Guidelines for Assessment of Gait and Reference Values for Spatiotemporal Gait Parameters in Older Adults: The Biomathics and Canadian Gait Consortiums Initiative

    Olivier Beauchet

    2017-08-01

    Full Text Available Background: Gait disorders, a highly prevalent condition in older adults, are associated with several adverse health consequences. Gait analysis allows qualitative and quantitative assessments of gait that improves the understanding of mechanisms of gait disorders and the choice of interventions. This manuscript aims (1 to give consensus guidance for clinical and spatiotemporal gait analysis based on the recorded footfalls in older adults aged 65 years and over, and (2 to provide reference values for spatiotemporal gait parameters based on the recorded footfalls in healthy older adults free of cognitive impairment and multi-morbidities.Methods: International experts working in a network of two different consortiums (i.e., Biomathics and Canadian Gait Consortium participated in this initiative. First, they identified items of standardized information following the usual procedure of formulation of consensus findings. Second, they merged databases including spatiotemporal gait assessments with GAITRite® system and clinical information from the “Gait, cOgnitiOn & Decline” (GOOD initiative and the Generation 100 (Gen 100 study. Only healthy—free of cognitive impairment and multi-morbidities (i.e., ≤ 3 therapeutics taken daily—participants aged 65 and older were selected. Age, sex, body mass index, mean values, and coefficients of variation (CoV of gait parameters were used for the analyses.Results: Standardized systematic assessment of three categories of items, which were demographics and clinical information, and gait characteristics (clinical and spatiotemporal gait analysis based on the recorded footfalls, were selected for the proposed guidelines. Two complementary sets of items were distinguished: a minimal data set and a full data set. In addition, a total of 954 participants (mean age 72.8 ± 4.8 years, 45.8% women were recruited to establish the reference values. Performance of spatiotemporal gait parameters based on the recorded

  15. Balance confidence is related to features of balance and gait in individuals with chronic stroke

    Schinkel-Ivy, Alison; Wong, Jennifer S.; Mansfield, Avril

    2016-01-01

    Reduced balance confidence is associated with impairments in features of balance and gait in individuals with sub-acute stroke. However, an understanding of these relationships in individuals at the chronic stage of stroke recovery is lacking. This study aimed to quantify relationships between balance confidence and specific features of balance and gait in individuals with chronic stroke. Participants completed a balance confidence questionnaire and clinical balance assessment (quiet standing, walking, and reactive stepping) at 6 months post-discharge from inpatient stroke rehabilitation. Regression analyses were performed using balance confidence as a predictor variable and quiet standing, walking, and reactive stepping outcome measures as the dependent variables. Walking velocity was positively correlated with balance confidence, while medio-lateral centre of pressure excursion (quiet standing) and double support time, step width variability, and step time variability (walking) were negatively correlated with balance confidence. This study provides insight into the relationships between balance confidence and balance and gait measures in individuals with chronic stroke, suggesting that individuals with low balance confidence exhibited impaired control of quiet standing as well as walking characteristics associated with cautious gait strategies. Future work should identify the direction of these relationships to inform community-based stroke rehabilitation programs for individuals with chronic stroke, and determine the potential utility of incorporating interventions to improve balance confidence into these programs. PMID:27955809

  16. Effect of rhythmic auditory stimulation on gait performance in children with spastic cerebral palsy.

    Kwak, Eunmi Emily

    2007-01-01

    The purpose of this study was to use Rhythmic Auditory Stimulation (RAS) for children with spastic cerebral palsy (CP) in a clinical setting in order to determine its effectiveness in gait training for ambulation. RAS has been shown to improve gait performance in patients with significant gait deficits. All 25 participants (6 to 20 years old) had spastic CP and were ambulatory, but needed to stabilize and gain more coordinated movement. Participants were placed in three groups: the control group, the therapist-guided training (TGT) group, and the self-guided training (SGT) group. The TGT group showed a statistically significant difference in stride length, velocity, and symmetry. The analysis of the results in SGT group suggests that the self-guided training might not be as effective as therapist-guided depending on motivation level. The results of this study support three conclusions: (a) RAS does influence gait performance of people with CP; (b) individual characteristics, such as cognitive functioning, support of parents, and physical ability play an important role in designing a training application, the effectiveness of RAS, and expected benefits from the training; and (c) velocity and stride length can be improved by enhancing balance, trajectory, and kinematic stability without increasing cadence.

  17. Influence of gait mode and body orientation on following a walking avatar.

    Meerhoff, L Rens A; de Poel, Harjo J; Jowett, Tim W D; Button, Chris

    2017-08-01

    Regulating distance with a moving object or person is a key component of human movement and of skillful interpersonal coordination. The current set of experiments aimed to assess the role of gait mode and body orientation on distance regulation using a cyclical locomotor tracking task in which participants followed a virtual leader. In the first experiment, participants moved in the backward-forward direction while the body orientation of the virtual leader was manipulated (i.e., facing towards, or away from the follower), hence imposing an incongruence in gait mode between leader and follower. Distance regulation was spatially less accurate when followers walked backwards. Additionally, a clear trade-off was found between spatial leader-follower accuracy and temporal synchrony. Any perceptual effects were overshadowed by the effect of one's gait mode. In the second experiment we examined lateral following. The results suggested that lateral following was also constrained strongly by perceptual information presented by the leader. Together, these findings demonstrated how locomotor tracking depends on gait mode, but also on the body orientation of whoever is being followed. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Body mass index affects knee joint mechanics during gait differently with and without moderate knee osteoarthritis.

    Harding, Graeme T; Hubley-Kozey, Cheryl L; Dunbar, Michael J; Stanish, William D; Astephen Wilson, Janie L

    2012-11-01

    Obesity is a highly cited risk factor for knee osteoarthritis (OA), but its role in knee OA pathogenesis and progression is not as clear. Excess weight may contribute to an increased mechanical burden and altered dynamic movement and loading patterns at the knee. The objective of this study was to examine the interacting role of moderate knee OA disease presence and obesity on knee joint mechanics during gait. Gait analysis was performed on 104 asymptomatic and 140 individuals with moderate knee OA. Each subject group was divided into three body mass categories based on body mass index (BMI): healthy weight (BMI30). Three-dimensional knee joint angles and net external knee joint moments were calculated and waveform principal component analysis (PCA) was applied to extract major patterns of variability from each. PC scores for major patterns were compared between groups using a two-factor ANOVA. Significant BMI main effects were found in the pattern of the knee adduction moment, the knee flexion moment, and the knee rotation moment during gait. Two interaction effects between moderate OA disease presence and BMI were also found that described different changes in the knee flexion moment and the knee flexion angle with increased BMI with and without knee OA. Our results suggest that increased BMI is associated with different changes in biomechanical patterns of the knee joint during gait depending on the presence of moderate knee OA. Copyright © 2012 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

  19. Design, simulation and modelling of auxiliary exoskeleton to improve human gait cycle.

    Ashkani, O; Maleki, A; Jamshidi, N

    2017-03-01

    Exoskeleton is a walking assistance device that improves human gait cycle through providing auxiliary force and transferring physical load to the stronger muscles. This device takes the natural state of organ and follows its natural movement. Exoskeleton functions as an auxiliary device to help those with disabilities in hip and knee such as devotees, elderly farmers and agricultural machinery operators who suffer from knee complications. In this research, an exoskeleton designed with two screw jacks at knee and hip joints. To simulate extension and flexion movements of the leg joints, bearings were used at the end of hip and knee joints. The generated torque and motion angles of these joints obtained as well as the displacement curves of screw jacks in the gait cycle. Then, the human gait cycle was simulated in stance and swing phases and the obtained torque curves were compared. The results indicated that they followed the natural circle of the generated torque in joints with a little difference from each other. The maximum displacement obtained 4 and 6 cm in hip and knee joints jack respectively. The maximum torques in hip and knee joints were generated in foot contact phase. Also the minimum torques in hip and knee joints were generated in toe off and heel off phases respectively.

  20. Influence of different degrees of bilateral emulated contractures at the triceps surae on gait kinematics: The difference between gastrocnemius and soleus.

    Attias, M; Bonnefoy-Mazure, A; De Coulon, G; Cheze, L; Armand, S

    2017-10-01

    Ankle plantarflexion contracture results from a permanent shortening of the muscle-tendon complex. It often leads to gait alterations. The objective of this study was to compare the kinematic adaptations of different degrees of contractures and between isolated bilateral gastrocnemius and soleus emulated contractures using an exoskeleton. Eight combinations of contractures were emulated bilaterally on 10 asymptomatic participants using an exoskeleton that was able to emulate different degrees of contracture of gastrocnemius (biarticular muscle) and soleus (monoarticular muscle), corresponding at 0°, 10°, 20°, and 30° ankle plantarflexion contracture (knee-flexed and knee-extended). Range of motion was limited by ropes attached for soleus on heel and below the knee and for gastrocnemius on heel and above the knee. A gait analysis session was performed to evaluate the effect of these different emulated contractures on the Gait Profile Score, walking speed and gait kinematics. Gastrocnemius and soleus contractures influence gait kinematics, with an increase of the Gait Profile Score. Significant differences were found in the kinematics of the ankles, knees and hips. Contractures of soleus cause a more important decrease in the range of motion at the ankle than the same degree of gastrocnemius contractures. Gastrocnemius contractures cause greater knee flexion (during the stance phase) and hip flexion (during all the gait cycle) than the same level of soleus contractures. These results can support the interpretation of the Clinical Gait Analysis data by providing a better understanding of the effect of isolate contracture of soleus and gastrocnemius on gait kinematics. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Association of Dual-Task Gait With Incident Dementia in Mild Cognitive Impairment: Results From the Gait and Brain Study.

    Montero-Odasso, Manuel M; Sarquis-Adamson, Yanina; Speechley, Mark; Borrie, Michael J; Hachinski, Vladimir C; Wells, Jennie; Riccio, Patricia M; Schapira, Marcelo; Sejdic, Ervin; Camicioli, Richard M; Bartha, Robert; McIlroy, William E; Muir-Hunter, Susan

    2017-07-01

    Gait performance is affected by neurodegeneration in aging and has the potential to be used as a clinical marker for progression from mild cognitive impairment (MCI) to dementia. A dual-task gait test evaluating the cognitive-motor interface may predict dementia progression in older adults with MCI. To determine whether a dual-task gait test is associated with incident dementia in MCI. The Gait and Brain Study is an ongoing prospective cohort study of community-dwelling older adults that enrolled 112 older adults with MCI. Participants were followed up for 6 years, with biannual visits including neurologic, cognitive, and gait assessments. Data were collected from July 2007 to March 2016. Incident all-cause dementia was the main outcome measure, and single- and dual-task gait velocity and dual-task gait costs were the independent variables. A neuropsychological test battery was used to assess cognition. Gait velocity was recorded under single-task and 3 separate dual-task conditions using an electronic walkway. Dual-task gait cost was defined as the percentage change between single- and dual-task gait velocities: ([single-task gait velocity - dual-task gait velocity]/ single-task gait velocity) × 100. Cox proportional hazard models were used to estimate the association between risk of progression to dementia and the independent variables, adjusted for age, sex, education, comorbidities, and cognition. Among 112 study participants with MCI, mean (SD) age was 76.6 (6.9) years, 55 were women (49.1%), and 27 progressed to dementia (24.1%), with an incidence rate of 121 per 1000 person-years. Slow single-task gait velocity (gait cost while counting backward (HR, 3.79; 95% CI, 1.57-9.15; P = .003) and naming animals (HR, 2.41; 95% CI, 1.04-5.59; P = .04) were associated with dementia progression (incidence rate, 155 per 1000 person-years). The models remained robust after adjusting by baseline cognition except for dual-task gait cost when dichotomized. Dual

  2. Temperature-dependent Raman and ultraviolet photoelectron spectroscopy studies on phase transition behavior of VO{sub 2} films with M1 and M2 phases

    Okimura, Kunio, E-mail: okifn@keyaki.cc.u-tokai.ac.jp; Hanis Azhan, Nurul [Graduate School of Engineering, Tokai University, Hiratsuka 259-1292 (Japan); Hajiri, Tetsuya [UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan); Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Kimura, Shin-ichi [UVSOR Facility, Institute for Molecular Science, Okazaki 444-8585 (Japan); Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871 (Japan); Zaghrioui, Mustapha; Sakai, Joe [GREMAN, UMR 7347 CNRS, Université François Rabelais de Tours, Parc de Grandmont, 37200 Tours (France)

    2014-04-21

    Structural and electronic phase transitions behavior of two polycrystalline VO{sub 2} films, one with pure M1 phase and the other with pure M2 phase at room temperature, were investigated by temperature-controlled Raman spectroscopy and ultraviolet photoelectron spectroscopy (UPS). We observed characteristic transient dynamics in which the Raman modes at 195 cm{sup −1} (V-V vibration) and 616 cm{sup −1} (V-O vibration) showed remarkable hardening along the temperature in M1 phase film, indicating the rearrangements of V-V pairs and VO{sub 6} octahedra. It was also shown that the M1 Raman mode frequency approached those of invariant M2 peaks before entering rutile phase. In UPS spectra with high energy resolution of 0.03 eV for the M2 phase film, narrower V{sub 3d} band was observed together with smaller gap compared to those of M1 phase film, supporting the nature of Mott insulator of M2 phase even in the polycrystalline film. Cooperative behavior of lattice rearrangements and electronic phase transition was suggested for M1 phase film.

  3. Does patella lowering improve crouch gait in cerebral palsy? Comparative retrospective study.

    Desailly, E; Thévenin-Lemoine, C; Khouri, N

    2017-09-01

    Patella lowering aims to improve quadriceps function as a means of correcting crouch gait in patients with cerebral palsy. Few studies have assessed the effects of patella lowering as a component of multilevel surgery. Including patella lowering into the components of multilevel surgery is beneficial in patients with crouch gait and patella alta. In 12 lower limbs with patella alta (Caton-Deschamps index>1.4) in 41 children with cerebral palsy, patella lowering was performed, without distal femoral extension osteotomy or hamstring release. Among limbs with similar surgical procedures (e.g., hamstring lengthening, rectus femoris transfer) except for patella lowering, controls were selected retrospectively by matching on a propensity score for patella lowering. The propensity score was computed based on preoperative knee flexion contracture, knee extension lag, and minimum knee flexion at mid-stance. Clinical and 3D kinematic data were compared between the two groups. The improvement in minimum knee flexion at mid-stance was significantly greater in the group with patellar lowering (-24°±12°vs. -12°±7°). The Gait Deviation Index improved similarly in the two groups. Knee flexion contracture improved only in the group with patellar lowering. Extension lag did not improve in either group. Peak knee flexion during the swing phase remained unchanged in both groups. Patellar lowering is effective in diminishing minimum knee flexion at mid-stance in patients with patella alta and crouch gait due to cerebral palsy. Patellar lowering has not adverse effects on gait. These findings cannot be assumed to apply to patients with normal patellar height. IV (retrospective study). Copyright © 2017. Published by Elsevier Masson SAS.

  4. Six degree-of-freedom knee joint kinematics in obese individuals with knee pain during gait.

    Li, Jing-Sheng; Tsai, Tsung-Yuan; Felson, David T; Li, Guoan; Lewis, Cara L

    2017-01-01

    Knee joint pain is a common symptom in obese individuals and walking is often prescribed as part of management programs. Past studies in obese individuals have focused on standing alignment and kinematics in the sagittal and coronal planes. Investigation of 6 degree-of-freedom (6DOF) knee joint kinematics during standing and gait is important to thoroughly understand knee function in obese individuals with knee pain. This study aimed to investigate the 6DOF knee joint kinematics in standing and during gait in obese patients using a validated fluoroscopic imaging system. Ten individuals with obesity and knee pain were recruited. While standing, the knee was in 7.4±6.3°of hyperextension, 2.8±3.3° of abduction and 5.6±7.3° of external rotation. The femoral center was located 0.7±3.1mm anterior and 5.1±1.5mm medial to the tibial center. During treadmill gait, the sagittal plane motion, i.e., flexion/extension and anterior-posterior translation, showed a clear pattern. Specifically, obese individuals with knee pain maintained the knee in more flexion and more anterior tibial translation during most of the stance phase of the gait cycle and had a reduced total range of knee flexion when compared to a healthy non-obese group. In conclusion, obese individuals with knee pain used hyperextension knee posture while standing, but maintained the knee in more flexion during gait with reduced overall range of motion in the 6DOF analysis.

  5. A Surgical Model of Posttraumatic Osteoarthritis With Histological and Gait Validation.

    Zahoor, Talal; Mitchell, Reed; Bhasin, Priya; Schon, Lew; Zhang, Zijun

    2016-07-01

    Posttraumatic osteoarthritis (PTOA) is secondary to an array of joint injuries. Animal models are useful tools for addressing the uniqueness of PTOA progression in each type of joint injury and developing strategies for PTOA prevention and treatment. Intra-articular fracture induces PTOA pathology. Descriptive laboratory study. Through a parapatellar incision, the medial tibial plateau was exposed in the left knees of 8 Sprague-Dawley rats. Osteotomy at the midpoint between the tibial crest and the outermost portion of the medial tibial plateau, including the covering articular cartilage, was performed using a surgical blade. The fractured medial tibial plateau was fixed with 2 needles transversely. The fractured knees were not immobilized. Before and after surgery, rat gait was recorded. Rats were sacrificed at week 8, and their knees were harvested for histology. After intra-articular fracture, the affected limbs altered gait from baseline (week 0). In the first 2 weeks, the gait of the operated limbs featured a reduced paw print intensity and stride length but increased maximal contact and stance time. Reduction of maximal and mean print area and duty cycle (the percentage of stance phase in a step) was present from week 1 to week 5. Only print length was reduced in weeks 7 and 8. At week 8, histology of the operated knees demonstrated osteoarthritic pathology. The severity of the PTOA pathology did not correlate with the changes of print length at week 8. Intra-articular fracture of the medial tibial plateau effectively induced PTOA in rat knees. During PTOA development, the injured limbs demonstrated characteristic gait. Intra-articular fracture represents severe joint injury and associates with a high rate of PTOA. This animal model, with histologic and gait validations, can be useful for future studies of PTOA prevention and early diagnosis.

  6. Knee Kinematic Improvement After Total Knee Replacement Using a Simplified Quantitative Gait Analysis Method

    Hassan Sarailoo

    2013-10-01

    Full Text Available Objectives: The aim of this study was to extract suitable spatiotemporal and kinematic parameters to determine how Total Knee Replacement (TKR alters patients’ knee kinematics during gait, using a rapid and simplified quantitative two-dimensional gait analysis procedure. Methods: Two-dimensional kinematic gait pattern of 10 participants were collected before and after the TKR surgery, using a 60 Hz camcorder in sagittal plane. Then, the kinematic parameters were extracted using the gait data. A student t-test was used to compare the group-average of spatiotemporal and peak kinematic characteristics in the sagittal plane. The knee condition was also evaluated using the Oxford Knee Score (OKS Questionnaire to ensure thateach subject was placed in the right group. Results: The results showed a significant improvement in knee flexion during stance and swing phases after TKR surgery. The walking speed was increased as a result of stride length and cadence improvement, but this increment was not statistically significant. Both post-TKR and control groups showed an increment in spatiotemporal and peak kinematic characteristics between comfortable and fast walking speeds. Discussion: The objective kinematic parameters extracted from 2D gait data were able to show significant improvements of the knee joint after TKR surgery. The patients with TKR surgery were also able to improve their knee kinematics during fast walking speed equal to the control group. These results provide a good insight into the capabilities of the presented method to evaluate knee functionality before and after TKR surgery and to define a more effective rehabilitation program.

  7. Can we improve gait skills in chronic hemiplegics? A randomised control trial with gait trainer.

    Dias, D; Laíns, J; Pereira, A; Nunes, R; Caldas, J; Amaral, C; Pires, S; Costa, A; Alves, P; Moreira, M; Garrido, N; Loureiro, L

    2007-12-01

    Partial body weight support (PBWS) is an accepted treatment for hemiplegic patients. The aim of this study is to compare the efficiency of gait trainer with conventional treatment on the gait management after stroke. Forty chronic post-stroke hemiplegics were part of a prospective research. Inclusion criteria were: first ever stroke in a chronic stage with stabilised motor deficits; age >18 and gait trainer, for the same period of time and frequency. Assessment tools: Motricity Index (MI); Toulouse Motor Scale (TMS); modified Ashworth Spasticity Scale (mASS); Berg Balance Scale (BBS); Rivermead Mobility Index (RMI); Fugl-Meyer Stroke Scale (F-MSS); Functional Ambulation Category (FAC); Barthel Index (BI); 10 meters, time up and go (TUG), 6 minutes, and step tests. EG and CG did the assessments before treatment (T(0)), right after treatment (T(1)), and on follow-up, 3 months later (T(2)). CG and EG were homogenous in all the variables at T(0). CG and EG showed improvement in almost all the assessment scales after treatment, although only some with relevant differences. EG showed statistically relevant improvement on T(1) and on T(2) in several of the assessment tools, whereas CG only showed statistically significant improvement after T(1) and only in some of the assessment tools. Both groups of chronic hemiplegic patients improved after either PBWS with gait trainer or Bobath treatment. Only subjects undergoing PBWS with gait trainer maintained functional gain after 3 months.

  8. Hardware Development and Locomotion Control Strategy for an Over-Ground Gait Trainer: NaTUre-Gaits.

    Luu, Trieu Phat; Low, Kin Huat; Qu, Xingda; Lim, Hup Boon; Hoon, Kay Hiang

    2014-01-01

    Therapist-assisted body weight supported (TABWS) gait rehabilitation was introduced two decades ago. The benefit of TABWS in functional recovery of walking in spinal cord injury and stroke patients has been demonstrated and reported. However, shortage of therapists, labor-intensiveness, and short duration of training are some limitations of this approach. To overcome these deficiencies, robotic-assisted gait rehabilitation systems have been suggested. These systems have gained attentions from researchers and clinical practitioner in recent years. To achieve the same objective, an over-ground gait rehabilitation system, NaTUre-gaits, was developed at the Nanyang Technological University. The design was based on a clinical approach to provide four main features, which are pelvic motion, body weight support, over-ground walking experience, and lower limb assistance. These features can be achieved by three main modules of NaTUre-gaits: 1) pelvic assistance mechanism, mobile platform, and robotic orthosis. Predefined gait patterns are required for a robotic assisted system to follow. In this paper, the gait pattern planning for NaTUre-gaits was accomplished by an individual-specific gait pattern prediction model. The model generates gait patterns that resemble natural gait patterns of the targeted subjects. The features of NaTUre-gaits have been demonstrated by walking trials with several subjects. The trials have been evaluated by therapists and doctors. The results show that 10-m walking trial with a reduction in manpower. The task-specific repetitive training approach and natural walking gait patterns were also successfully achieved.

  9. Treatment of Gait Ignition Failure with Ropinirole

    Alexis N. Cohen-Oram

    2014-10-01

    Full Text Available Gait ignition failure (GIF is a syndrome characterized by hesitation or inability to initiate gait from a static position. It may occur in a variety of conditions, including normal pressure hydrocephalus, subcortical vascular disease, parkinsonian syndromes and a variety of focal lesions. Previous information on the treatment of GIF has been primarily anecdotal, but there have been a few reports of response to dopamine agonists. We report a 63-year-old man with anoxic encephalopathy who developed GIF nine years after the initial anoxic insult. The patient’s GIF responded robustly, albeit transiently, to ropinirole. MRI was unrevealing, but a positron emission tomography scan showed hypometabolism in the deep frontal ACA/MCA watershed area; this may have disconnected the basal ganglia from the motor cortex and/or interrupted dopaminergic mesocortical transmission. Our understanding of the pathophysiology and the treatment of GIF remains limited, but there may be at least a limited therapeutic role for dopamine agonists.

  10. Neglected Alkaptonuric Patient Presenting with Steppage Gait

    Babak Mirzashahi

    2016-04-01

    Full Text Available Even though intervertebral disc degeneration can be found in the natural course of alkaptonuria, detection of the disease by black disc color change in a patient without any other presentation of alkaptonuria is an exceptionally rare condition. We have reported a very rare case of alkaptonuria presented with low back pain and steppage gait in a 51-year-old male with a complaint of chronic low-back pain and steppage gait who was operated on for prolapsed lumbar disc herniation. Intraoperatively his lumbar disk was discovered to be black. The alkaptonuria diagnosis was considered after histopathological examination of the black disc material and elevated urinary concentration of homogentisic acid confirmed the diagnosis. To our knowledge, this presentation has not been reported previously in literature.

  11. Effects of Novel Guidance Tubing Gait on Electromyographic Neuromuscular Imbalance and Joint Angular Kinematics During Locomotion in Hemiparetic Stroke Patients.

    Lee, Jeong J; You, Joshua Sung H

    2017-12-01

    To compare the immediate effects of conventional treadmill gait and guidance tubing gait (GTG) on electromyographic neuromuscular imbalance and knee joint kinematics in hemiparetic gait. Case-control study. University medical center. Participants (N=33; 19 men, 14 women) were patients with hemiparetic stroke (n=18 [experimental]; mean age ± SD, 39.2±16.8y) and healthy controls (n=15; mean age ± SD, 26.3±2.6y). The GTG was provided for approximately 30 minutes and involved application of an assistive guidance force using the tubing, specifically to improve knee joint stabilization during midstance and increase knee joint flexion during midswing phase. Clinical tests included the Korean Mini-Mental State Examination, Modified Ashworth Scale, Berg Balance Scale, manual muscle test, and knee joint range of motion and sensory tests. Knee joint muscle electromyographic and kinematic analyses were determined at pretest and posttest. After the intervention, the experimental group showed significantly greater improvements in balanced quadriceps and hamstring electromyographic coactivation and knee joint kinematics relative to the control group (P=.005). The GTG intervention decreased overactive hamstring activity (P=.018) and reciprocally increased quadriceps activity (Pjoint kinematic analysis showed significant changes in the hemiparetic stroke group (P=.004). This study demonstrates the effectiveness of the tubing gait condition to restore knee joint muscle imbalance and kinematics in individuals with hemiparetic stroke who present with an abnormal hyperextension knee gait. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  12. The effects of dual tasking on gait synchronization during over-ground side-by-side walking.

    Zivotofsky, Ari Z; Bernad-Elazari, Hagar; Grossman, Pnina; Hausdorff, Jeffrey M

    2018-03-23

    Recent studies have shown that gait synchronization during natural walking is not merely anecdotal, but it is a repeatable phenomenon that is quantifiable and is apparently related to available sensory feedback modalities. However, the mechanisms underlying this phase-locking of gait have only recently begun to be investigated. For example, it is not known what role, if any, attention plays. We employed a dual tasking paradigm in order to investigate the role attention plays in gait synchronization. Sixteen pairs of subjects walked under six conditions that manipulated the available sensory feedback and the degree of difficulty of the dual task, i.e., the attention. Movement was quantified using a trunk-mounted tri-axial accelerometer. A gait synchronization index (GSI) was calculated in order to quantify the degree of synchronization of the gait pattern. A simple dual task resulted in an increased level of synchronization, whereas a more complex dual task lead to a reduction in synchronization. Handholding increased synchronization, compared to the same attention condition without handholding. These results indicate that in order for two walkers to synchronize, some level of attention is apparently required, such that a relatively complex dual task utilizes enough attentional resources to reduce the occurrence of synchronization. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. Impact of serial gait analyses on long-term outcome of hippotherapy in children and adolescents with cerebral palsy.

    Mutoh, Tomoko; Mutoh, Tatsushi; Tsubone, Hirokazu; Takada, Makoto; Doumura, Misato; Ihara, Masayo; Shimomura, Hideo; Taki, Yasuyuki; Ihara, Masahiro

    2018-02-01

    The aim of this study was to obtain data of gait parameters on predicting long-term outcome of hippotherapy. In 20 participants (4-19 years; GMFCS levels I to III) with cerebral palsy (CP), gait and balance abilities were examined after 10-m walking test using a portable motion recorder. Hippotherapy was associated with increased Gross Motor Function Measure (GMFM)-66 at 1 year from the baseline (P Hippotherapy increased stride length, walking speed, and mean acceleration and decreased horizontal/vertical displacement ratio over time (P hippotherapy on motor and balance functions can be assessed from the early phase by serial monitoring of the gait parameters. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Asymmetry in gait pattern following tibial shaft fractures

    Larsen, Peter; Læssøe, Uffe; Rasmussen, Sten

    2017-01-01

    INTRODUCTION: Despite the high number of studies evaluating the outcomes following tibial shaft fractures, the literature lacks studies including objective assessment of patients' recovery regarding gait pattern. The purpose of the present study was to evaluate whether gait patterns at 6 and 12...... months post-operatively following intramedullary nailing of a tibial shaft fracture are different compared with a healthy reference population. PATIENTS AND METHODS: The study design was a prospective cohort study. The primary outcome measurement was the gait patterns at 6 and 12 months post......-operatively measured with a 6-metre-long pressure-sensitive mat. The mat registers footprints and present gait speed, cadence as well as temporal and spatial parameters of the gait cycle. Gait patterns were compared to a healthy reference population. RESULTS: 49 patients were included with a mean age of 43.1 years (18...

  15. Plantar pressure during gait in pregnant women

    Bertuit, Jeanne; Leyh, Clara; Rooze, Marcel; Feipel, Véronique

    2016-01-01

    Background: During pregnancy, physical and hormonal modifications occur. Morphologic alterations of the feet are found. These observations can induce alterations in plantar pressure. This study sought to investigate plantar pressures during gait in the last 4 months of pregnancy and in the postpartum period. A comparison with nulliparous women was conducted to investigate plantar pressure modifications during pregnancy. Methods: Fifty-eight women in the last 4 months of pregnancy, nine postpa...

  16. Effects of conventional overground gait training and a gait trainer with partial body weight support on spatiotemporal gait parameters of patients after stroke.

    Park, Byoung-Sun; Kim, Mee-Young; Lee, Lim-Kyu; Yang, Seung-Min; Lee, Won-Deok; Noh, Ji-Woong; Shin, Yong-Sub; Kim, Ju-Hyun; Lee, Jeong-Uk; Kwak, Taek-Yong; Lee, Tae-Hyun; Kim, Ju-Young; Kim, Junghwan

    2015-05-01

    [Purpose] The purpose of this study was to confirm the effects of both conventional overground gait training (CGT) and a gait trainer with partial body weight support (GTBWS) on spatiotemporal gait parameters of patients with hemiparesis following chronic stroke. [Subjects and Methods] Thirty stroke patients were alternately assigned to one of two treatment groups, and both groups underwent CGT and GTBWS. [Results] The functional ambulation classification on the affected side improved significantly in the CGT and GTBWS groups. Walking speed also improved significantly in both groups. [Conclusion] These results suggest that the GTBWS in company with CGT may be, in part, an effective method of gait training for restoring gait ability in patients after a stroke.

  17. Visual Bias Predicts Gait Adaptability in Novel Sensory Discordant Conditions

    Brady, Rachel A.; Batson, Crystal D.; Peters, Brian T.; Mulavara, Ajitkumar P.; Bloomberg, Jacob J.

    2010-01-01

    We designed a gait training study that presented combinations of visual flow and support-surface manipulations to investigate the response of healthy adults to novel discordant sensorimotor conditions. We aimed to determine whether a relationship existed between subjects visual dependence and their postural stability and cognitive performance in a new discordant environment presented at the conclusion of training (Transfer Test). Our training system comprised a treadmill placed on a motion base facing a virtual visual scene that provided a variety of sensory challenges. Ten healthy adults completed 3 training sessions during which they walked on a treadmill at 1.1 m/s while receiving discordant support-surface and visual manipulations. At the first visit, in an analysis of normalized torso translation measured in a scene-movement-only condition, 3 of 10 subjects were classified as visually dependent. During the Transfer Test, all participants received a 2-minute novel exposure. In a combined measure of stride frequency and reaction time, the non-visually dependent subjects showed improved adaptation on the Transfer Test compared to their visually dependent counterparts. This finding suggests that individual differences in the ability to adapt to new sensorimotor conditions may be explained by individuals innate sensory biases. An accurate preflight assessment of crewmembers biases for visual dependence could be used to predict their propensities to adapt to novel sensory conditions. It may also facilitate the development of customized training regimens that could expedite adaptation to alternate gravitational environments.

  18. Gait Recognition and Walking Exercise Intensity Estimation

    Bor-Shing Lin

    2014-04-01

    Full Text Available Cardiovascular patients consult doctors for advice regarding regular exercise, whereas obese patients must self-manage their weight. Because a system for permanently monitoring and tracking patients’ exercise intensities and workouts is necessary, a system for recognizing gait and estimating walking exercise intensity was proposed. For gait recognition analysis, αβ filters were used to improve the recognition of athletic attitude. Furthermore, empirical mode decomposition (EMD was used to filter the noise of patients’ attitude to acquire the Fourier transform energy spectrum. Linear discriminant analysis was then applied to this energy spectrum for training and recognition. When the gait or motion was recognized, the walking exercise intensity was estimated. In addition, this study addressed the correlation between inertia and exercise intensity by using the residual function of the EMD and quadratic approximation to filter the effect of the baseline drift integral of the acceleration sensor. The increase in the determination coefficient of the regression equation from 0.55 to 0.81 proved that the accuracy of the method for estimating walking exercise intensity proposed by Kurihara was improved in this study.

  19. Gait Correlation Analysis Based Human Identification

    Jinyan Chen

    2014-01-01

    Full Text Available Human gait identification aims to identify people by a sequence of walking images. Comparing with fingerprint or iris based identification, the most important advantage of gait identification is that it can be done at a distance. In this paper, silhouette correlation analysis based human identification approach is proposed. By background subtracting algorithm, the moving silhouette figure can be extracted from the walking images sequence. Every pixel in the silhouette has three dimensions: horizontal axis (x, vertical axis (y, and temporal axis (t. By moving every pixel in the silhouette image along these three dimensions, we can get a new silhouette. The correlation result between the original silhouette and the new one can be used as the raw feature of human gait. Discrete Fourier transform is used to extract features from this correlation result. Then, these features are normalized to minimize the affection of noise. Primary component analysis method is used to reduce the features’ dimensions. Experiment based on CASIA database shows that this method has an encouraging recognition performance.

  20. Evaluating alternative gait strategies using evolutionary robotics.

    Sellers, William I; Dennis, Louise A; W -J, Wang; Crompton, Robin H

    2004-05-01

    Evolutionary robotics is a branch of artificial intelligence concerned with the automatic generation of autonomous robots. Usually the form of the robot is predefined and various computational techniques are used to control the machine's behaviour. One aspect is the spontaneous generation of walking in legged robots and this can be used to investigate the mechanical requirements for efficient walking in bipeds. This paper demonstrates a bipedal simulator that spontaneously generates walking and running gaits. The model can be customized to represent a range of hominoid morphologies and used to predict performance parameters such as preferred speed and metabolic energy cost. Because it does not require any motion capture data it is particularly suitable for investigating locomotion in fossil animals. The predictions for modern humans are highly accurate in terms of energy cost for a given speed and thus the values predicted for other bipeds are likely to be good estimates. To illustrate this the cost of transport is calculated for Australopithecus afarensis. The model allows the degree of maximum extension at the knee to be varied causing the model to adopt walking gaits varying from chimpanzee-like to human-like. The energy costs associated with these gait choices can thus be calculated and this information used to evaluate possible locomotor strategies in early hominids.

  1. Molecular Excitation Energies from Time-Dependent Density Functional Theory Employing Random-Phase Approximation Hessians with Exact Exchange.

    Heßelmann, Andreas

    2015-04-14

    Molecular excitation energies have been calculated with time-dependent density-functional theory (TDDFT) using random-phase approximation Hessians augmented with exact exchange contributions in various orders. It has been observed that this approach yields fairly accurate local valence excitations if combined with accurate asymptotically corrected exchange-correlation potentials used in the ground-state Kohn-Sham calculations. The inclusion of long-range particle-particle with hole-hole interactions in the kernel leads to errors of 0.14 eV only for the lowest excitations of a selection of three alkene, three carbonyl, and five azabenzene molecules, thus surpassing the accuracy of a number of common TDDFT and even some wave function correlation methods. In the case of long-range charge-transfer excitations, the method typically underestimates accurate reference excitation energies by 8% on average, which is better than with standard hybrid-GGA functionals but worse compared to range-separated functional approximations.

  2. Anatase phase stability and doping concentration dependent refractivity in codoped transparent conducting TiO{sub 2} films

    Chen, T L [Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan); Furubayashi, Y [Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan); Hirose, Y [Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan); Hitosugi, T [Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan); Shimada, T [Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan); Hasegawa, T [Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan)

    2007-10-07

    Nb{sub 0.06}Sn{sub x}Ti{sub 0.94-x}O{sub 2} (x {<=} 0.3) thin films were grown by a pulsed-laser deposition method with varying Sn concentration. Through a combinatorial technique, we find that Sn concentration can reach a maximum of about x = 0.3 while maintaining the stable anatase phase and epitaxy. A doping concentration dependence of the refractivity is revealed, in which refractivity reduction at a wavelength of {lambda} = 500 nm is estimated to be 12.4% for Nb{sub 0.06}Sn{sub 0.3} Ti{sub 0.64}O{sub 2} thin film. Sn doping induced band-gap blue shift can be contributed to the mixing of extended Sn 5s orbitals with the conduction band of TiO{sub 2}. Low resistivity on the order of 10{sup -4} {omega} cm at room temperature and high internal transmittance of more than 95% in the visible light region are exhibited for Nb{sub 0.06}Sn{sub x} Ti{sub 0.94-x}O{sub 2} thin films (x {<=} 0.2). Optical and transport analyses demonstrate that doping Sn into Nb{sub 0.06} Ti{sub 0.94}O{sub 2} can reduce the refractivity while maintaining low resistivity and high transparency.

  3. Anatase phase stability and doping concentration dependent refractivity in codoped transparent conducting TiO2 films

    Chen, T L; Furubayashi, Y; Hirose, Y; Hitosugi, T; Shimada, T; Hasegawa, T

    2007-01-01

    Nb 0.06 Sn x Ti 0.94-x O 2 (x ≤ 0.3) thin films were grown by a pulsed-laser deposition method with varying Sn concentration. Through a combinatorial technique, we find that Sn concentration can reach a maximum of about x = 0.3 while maintaining the stable anatase phase and epitaxy. A doping concentration dependence of the refractivity is revealed, in which refractivity reduction at a wavelength of λ = 500 nm is estimated to be 12.4% for Nb 0.06 Sn 0.3 Ti 0.64 O 2 thin film. Sn doping induced band-gap blue shift can be contributed to the mixing of extended Sn 5s orbitals with the conduction band of TiO 2 . Low resistivity on the order of 10 -4 Ω cm at room temperature and high internal transmittance of more than 95% in the visible light region are exhibited for Nb 0.06 Sn x Ti 0.94-x O 2 thin films (x ≤ 0.2). Optical and transport analyses demonstrate that doping Sn into Nb 0.06 Ti 0.94 O 2 can reduce the refractivity while maintaining low resistivity and high transparency

  4. H4 replication-dependent diacetylation and Hat1 promote S-phase chromatin assembly in vivo

    Ejlassi-Lassallette, Aïda; Mocquard, Eloïse; Arnaud, Marie-Claire; Thiriet, Christophe

    2011-01-01

    While specific posttranslational modification patterns within the H3 and H4 tail domains are associated with the S-phase, their actual functions in replication-dependent chromatin assembly have not yet been defined. Here we used incorporation of trace amounts of recombinant proteins into naturally synchronous macroplasmodia of Physarum polycephalum to examine the function of H3 and H4 tail domains in replication-coupled chromatin assembly. We found that the H3/H4 complex lacking the H4 tail domain was not efficiently recovered in nuclei, whereas depletion of the H3 tail domain did not impede nuclear import but chromatin assembly failed. Furthermore, our results revealed that the proper pattern of acetylation on the H4 tail domain is required for nuclear import and chromatin assembly. This is most likely due to binding of Hat1, as coimmunoprecipitation experiments showed Hat1 associated with predeposition histones in the cytoplasm and with replicating chromatin. These results suggest that the type B histone acetyltransferase assists in shuttling the H3/H4 complex from cytoplasm to the replication forks. PMID:21118997

  5. Analysis of dual-phase-lag thermal behaviour in layered films with temperature-dependent interface thermal resistance

    Liu, K-C

    2005-01-01

    This work analyses theoretically the dual-phase-lag thermal behaviour in two-layered thin films with an interface thermal resistance, which is predicted by the radiation boundary condition model. The effect of the interface thermal resistance on the transmission-reflection phenomenon, induced by a pulsed volumetric source adjacent