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"Reactive stepping"

Vicki L Gray, Chieh-Ling Yang, Sandy McCombe Waller, Mark W Rogers
BACKGROUND AND PURPOSE: Falls commonly occur as weight is transferred laterally, and impaired reactive stepping responses are associated with falls after stroke. The purpose of this study was to examine differences in and the determinants of mediolateral (M-L) protective stepping strategies when pulled off balance toward the paretic and nonparetic sides. METHODS: Eighteen individuals more than 6 months poststroke were pulled in the M-L direction by a lateral waist-pull perturbation system...
October 2017: Journal of Neurologic Physical Therapy: JNPT
Digna de Kam, Jolanda M B Roelofs, Amber K B D Bruijnes, Alexander C H Geurts, Vivian Weerdesteyn
BACKGROUND AND OBJECTIVE: Postural muscle responses are often impaired after stroke. We aimed to identify the contribution of deficits in very early postural responses to poorer reactive balance capacity, with a particular focus on reactive stepping as a key strategy for avoiding falls. METHODS: A total of 34 chronic stroke survivors and 17 controls were subjected to translational balance perturbations in 4 directions. We identified the highest perturbation intensity that could be recovered without stepping (single stepping threshold [SST]) and with maximally 1 step (multiple stepping threshold [MST])...
July 1, 2017: Neurorehabilitation and Neural Repair
Alexander J Hunt, Brooke M Odle, Lisa M Lombardo, Musa L Audu, Ronald J Triolo
BACKGROUND: Implanted motor system neuroprostheses can be effective at increasing personal mobility of persons paralyzed by spinal cord injuries. However, currently available neural stimulation systems for standing employ patterns of constant activation and are unreactive to changing postural demands. METHODS: In this work, we developed a closed-loop controller for detecting forward-directed body disturbances and initiating a stabilizing step in a person with spinal cord injury...
June 10, 2017: Journal of Neuroengineering and Rehabilitation
Ki Seok Kim, Ki Hyun Kim, Yeonsig Nam, Jaeho Jeon, Soonmin Yim, Eric Singh, Jin Yong Lee, Sung Joo Lee, Yeon Sik Jung, Geun Young Yeom, Dong Woo Kim
Among the layered transition metal dichalcogenides (TMDs) that can form stable two-dimensional crystal structures, molybdenum disulfide (MoS2) has been intensively investigated because of its unique properties in various electronic and optoelectronic applications with different band gap energies from 1.29 to 1.9 eV as the number of layers decreases. To control the MoS2 layers, atomic layer etching (ALE) (which is a cyclic etching consisting of a radical-adsorption step such as Cl adsorption and a reacted-compound-desorption step via a low-energy Ar(+)-ion exposure) can be a highly effective technique to avoid inducing damage and contamination that occur during the reactive steps...
April 5, 2017: ACS Applied Materials & Interfaces
Christopher McCrum, Marissa H G Gerards, Kiros Karamanidis, Wiebren Zijlstra, Kenneth Meijer
BACKGROUND: Falls are a leading cause of injury among older adults and most often occur during walking. While strength and balance training moderately improve falls risk, training reactive recovery responses following sudden perturbations during walking may be more task-specific for falls prevention. The aim of this review was to determine the variety, characteristics and effectiveness of gait perturbation paradigms that have been used for improving reactive recovery responses during walking and reducing falls among healthy older adults...
2017: European Review of Aging and Physical Activity
Aimi L Forsyth, Serene S Paul, Natalie E Allen, Catherine Sherrington, Victor S C Fung, Colleen G Canning
BACKGROUND AND PURPOSE: Flexed truncal posture is common in people with Parkinson disease (PD); however, little is known about the mechanisms responsible or its effect on physical performance. This cross-sectional study aimed to establish the reliability of a truncal posture measurement and explore relationships between PD impairments and truncal posture, as well as truncal posture and balance and mobility. METHODS: A total of 82 people with PD participated. Truncal posture was measured in standing as the distance between vertebra C7 and a wall...
April 2017: Journal of Neurologic Physical Therapy: JNPT
Michele R Brumley, Pierre A Guertin, Giuliano Taccola
Locomotion is one of the most complex motor behaviors. Locomotor patterns change during early life, reflecting development of numerous peripheral and hierarchically organized central structures. Among them, the spinal cord is of particular interest since it houses the central pattern generator (CPG) for locomotion. This main command center is capable of eliciting and coordinating complex series of rhythmic neural signals sent to motoneurons and to corresponding target-muscles for basic locomotor activity. For a long-time, the CPG has been considered a black box...
December 14, 2016: Current Pharmaceutical Design
Alison Schinkel-Ivy, Jennifer S Wong, Avril Mansfield
BACKGROUND: Reduced balance confidence is associated with impairments in features of balance and gait in individuals with subacute stroke. However, an understanding of these relationships in individuals at the chronic stage of stroke recovery is lacking. This study aimed to quantify the relationships between balance confidence and specific features of balance and gait in individuals with chronic stroke. METHODS: Participants completed a balance confidence questionnaire and clinical balance assessment (quiet standing, walking, and reactive stepping) at 6 months postdischarge from inpatient stroke rehabilitation...
February 2017: Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association
Alison Schinkel-Ivy, Andrew H Huntley, Elizabeth L Inness, Avril Mansfield
Performance decrements in balance tasks are often observed when a secondary cognitive task is performed simultaneously. This study aimed to determine whether increased cognitive load resulted in altered reactive stepping in individuals with sub-acute stroke, compared to a reactive stepping trial with no secondary task. The secondary purpose was to determine whether differences existed between the first usual-response trial, subsequent usual-response trials, and the dual-task condition. Individuals with sub-acute stroke were exposed to external perturbations to elicit reactive steps...
October 2016: Heliyon
Tejal Kajrolkar, Tanvi Bhatt
Community-dwelling stroke survivors show a high incidence of falls with unexpected external perturbations during dynamic activities like walking. Previous evidence has demonstrated the importance of compensatory stepping to restore dynamic stability in response to perturbations in hemiparetic stroke survivors. However, these studies were limited to either stance perturbations or perturbation induced under the unaffected limb. This study aimed to compare the differences, if any, between the non-paretic and paretic sides in dynamic stability and protective stepping strategies when exposed to unexpected external perturbation during walking...
September 6, 2016: Journal of Biomechanics
Elizabeth L Inness, Avril Mansfield, Mark Bayley, William E McIlroy
BACKGROUND AND PURPOSE: Impaired features of reactive stepping, specifically delays in the early time to foot off (TFO) phase, are associated with increased fall rates after stroke. This study aimed to determine differences in, and determinants of, paretic and nonparetic limb TFO, and to determine whether both paretic and nonparetic TFO were associated with perturbation-evoked falls. METHODS: Retrospective chart review of 105 individuals with stroke was performed within an inpatient rehabilitation setting; each had received a standardized assessment of reactive balance control (in response to a perturbation) at time of discharge...
July 2016: Journal of Neurologic Physical Therapy: JNPT
Francesco Dose, Giuliano Taccola
OBJECTIVES: Explore the primary characteristics of afferent noisy stimuli, which optimally activate locomotor patterns at low intensity. MATERIALS AND METHODS: Intracellular and extracellular electrophysiological traces were derived from single motoneurons and from ventral roots, respectively. From these recordings, we obtained noisy stimulating protocols, delivered to a dorsal root (DR) of an isolated neonatal rat spinal cord, while recording fictive locomotion (FL) from ventral roots...
August 2016: Neuromodulation: Journal of the International Neuromodulation Society
Tyler B Weaver, Stephen N Robinovitch, Andrew C Laing, Yijian Yang
OBJECTIVES: To compare the fall characteristics of individuals with and without Parkinson's disease (PD) through the analysis of real-life falls captured on video. DESIGN: Observational cohort study. SETTING: Two long-term care facilities in British Columbia, Canada. PARTICIPANTS: Individuals living in long-term care (N=306; 16 with PD). MEASUREMENTS: Falls captured on video and analyzed (N=906; 71 in participants with PD)...
January 2016: Journal of the American Geriatrics Society
Yoshiro Okubo, Daniel Schoene, Stephen R Lord
OBJECTIVE: To examine the effects of stepping interventions on fall risk factors and fall incidence in older people. DATA SOURCE: Electronic databases (PubMed, EMBASE, CINAHL, Cochrane, CENTRAL) and reference lists of included articles from inception to March 2015. STUDY SELECTION: Randomised (RCT) or clinical controlled trials (CCT) of volitional and reactive stepping interventions that included older (minimum age 60) people providing data on falls or fall risk factors...
April 2017: British Journal of Sports Medicine
Lin Li, Frank Abild-Pedersen, Jeff Greeley, Jens K Nørskov
We present calculated adsorption energies of oxygen on gold and platinum clusters with up to 923 atoms (3 nm diameter) using density functional theory. We find that surface tension of the clusters induces a compression, which weakens the bonding of adsorbates compared with the bonding on extended surfaces. The effect is largest for close-packed surfaces and almost nonexistent on the more reactive steps and edges. The effect is largest at low coverage and decreases, even changing sign, at higher coverages where the strain changes from compressive to tensile...
October 1, 2015: Journal of Physical Chemistry Letters
Ruopeng Sun, John B Shea
The present study investigated the attention allocation during reactive stepping using a continuous finger-tapping task. Ten healthy young subjects were recruited to participate in this study. Subjects were required to perform a rapid voluntary step with either left or right leg after hearing an auditory tone while tapping their right index finger on a handhold numeric keypad. Step initiation conditions included simple and choice reaction forward stepping with three variants of continuous tapping task that were: (1) single task--no concurrent finger-tapping task; (2) dual task easy--one-button tapping task; (3) dual task hard--four-button tapping task...
April 2016: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Manjula Gandhi Selvaraj, Devi Shree Jayabal, Thenmozhi Srinivasan, Palanisamy Balasubramanie
A key differentiator in a competitive market place is customer satisfaction. As per Gartner 2012 report, only 75%-80% of IT projects are successful. Customer satisfaction should be considered as a part of business strategy. The associated project parameters should be proactively managed and the project outcome needs to be predicted by a technical manager. There is lot of focus on the end state and on minimizing defect leakage as much as possible. Focus should be on proactively managing and shifting left in the software life cycle engineering model...
2015: TheScientificWorldJournal
Prakruti Patel, Tanvi Bhatt
This study aimed to examine the effect of explicit cuing on reactive stepping with the paretic limb during slip-like perturbations in stroke survivors and to identify differences in postural stability and fall-risk while stepping with either limb. Eleven chronic hemiparetic stroke survivors received slip-like stance perturbations in no-cue (implicit, no instructions) and cued (explicit, instructions to step with paretic limb) conditions. Frequency of stepping with the paretic limb was recorded. Differences between non-paretic and paretic steps for falls, number of compensatory steps, relative center-of-mass position (X COM/BOS), and velocity (Ẋ(COM/BOS)), and vertical limb support (hip descent-Z hip) were analyzed...
November 2015: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
Cuiyun Hu, Caifang Yu, Yanhua Liu, Xianhui Hou, Xiaoyun Liu, Yunfei Hu, Changwen Jin
Evolution of enzymes plays a crucial role in obtaining new biological functions for all life forms. Arsenate reductases (ArsC) are several families of arsenic detoxification enzymes that reduce arsenate to arsenite, which can subsequently be extruded from cells by specific transporters. Among these, the Synechocystis ArsC (SynArsC) is structurally homologous to the well characterized thioredoxin (Trx)-coupled ArsC family but requires the glutaredoxin (Grx) system for its reactivation, therefore classified as a unique Trx/Grx-hybrid family...
September 4, 2015: Journal of Biological Chemistry
Pooja Salot, Prakruti Patel, Tanvi Bhatt
BACKGROUND: An effective compensatory stepping response is the first line of defense for preventing a fall during sudden large external perturbations. The biomechanical factors that contribute to heightened fall risk in survivors of stroke, however, are not clearly understood. It is known that impending sensorimotor and balance deficits poststroke predispose these individuals to a risk of fall during sudden external perturbations. OBJECTIVE: The purpose of this study was to examine the mechanism of fall risk in survivors of chronic stroke when exposed to sudden, slip-like forward perturbations in stance...
March 2016: Physical Therapy
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