Autonomous healing of fatigue cracks via cold welding.

Fatigue in metals involves gradual failure through incremental propagation of cracks under repetitive mechanical load. In structural applications, fatigue accounts for up to 90% of in-service failure1,2. Prevention of fatigue relies on implementation of large safety factors and inefficient overdesign3. In traditional metallurgical design for fatigue resistance, microstructures are developed to either arrest or slow the progression of cracks. Crack growth is assumed to be irreversible. By contrast, in other material classes, there is a compelling alternative based on latent healing mechanisms and damage reversal4-9. Here, we report that fatigue cracks in pure metals can undergo intrinsic self-healing. We directly observe the early progression of nanoscale fatigue cracks, and as expected, the cracks advance, deflect and arrest at local microstructural barriers. However, unexpectedly, cracks were also observed to heal by a process that can be described as crack flank cold welding induced by a combination of local stress state and grain boundary migration. The premise that fatigue cracks can autonomously heal in metals through local interaction with microstructural features challenges the most fundamental theories on how engineers design and evaluate fatigue life in structural materials. We discuss the implications for fatigue in a variety of service environments.

The Buffalo Concussion Treadmill and Bike Tests in People With Mild-to-Moderate Traumatic Brain Injury: An Exploratory Clinical Audit.

OBJECTIVE: To assess the performance on the Buffalo Concussion Treadmill and Bike Tests in nonathletic people following a mild-to-moderate traumatic brain injury. SETTING: An outpatient rehabilitation clinic. PARTICIPANTS: Forty-nine patients with mild-to-moderate traumatic brain injury who underwent the Buffalo Concussion Treadmill or Bike Test as usual clinical care. DESIGN: A retrospective clinical audit. MAIN MEASURES: Demographics and brain injury-specific clinical data, Depression Anxiety Stress Scale; Rivermead Post-Concussion Symptom Questionnaire, and performance outcomes on the Buffalo Concussion Treadmill or Bike Test. RESULTS: Forty-nine patients (mean age: 33.7 ± 13.0 years), on average 56.2 ± 36.4 days post-injury, completed the Buffalo Concussion Treadmill or Bike Test. Fourteen patients stopped the test due to symptom exacerbation with a mean test duration of 8.1 ± 4.5 minutes, reaching an age-predicted maximum heart rate of 72.9% ± 12.4% and reporting a rating of perceived exertion of 13.4 ± 2.2. Those who terminated the test for other reasons had a significantly longer test duration (14.0 ± 4.7 minutes, P = .01), with a higher age-predicted maximum heart rate (83.3% ± 12.8%, P = .01) and rating of perceived exertion (17.0 ± 2.5, P = .01). Within the group who stopped for other reasons, 10 were due to symptoms deemed unrelated to the injury at the time of the test and 2 were stopped by the therapist for safety reasons. A significant but weak correlation between heart rate and rating of perceived exertion existed only for those who terminated the test for other reasons ( r = 0.38, P = .02). Overall, a shorter test duration was associated with higher scores of both self-reported depression ( r = -0.41, P < .01) and late postconcussion symptoms ( r = -0.40, P < .01). CONCLUSION: The Buffalo Concussion Treadmill or Bike Test can be used in the nonathletic mild-to-moderate traumatic brain injury population to differentiate between those who experience symptom exacerbation during exercise and those who do not based on symptom exacerbation, test duration, and poor perception of exertion. Further research is required to determine whether other reasons for test termination are related to the injury.

A study of the accuracy of the Fitbit Zip in measuring steps both indoors and outdoors in a mixed rehabilitation population.

OBJECTIVE: To assess (1) step count accuracy of the Fitbit Zip, compared to manual step count, in people receiving outpatient rehabilitation, in indoor and outdoor conditions, and (2) impact of slow walking speed on Fitbit accuracy. DESIGN: Observational study. SETTING: A metropolitan rehabilitation hospital. SUBJECTS: Adults (n = 88) attending a subacute rehabilitation outpatient clinic with walking speeds of between 0.4 and 1.0 m/s. INTERVENTIONS: Two 2-minute walk tests, one indoors and one outdoors, completed in random order. MAIN MEASURES: Step count recorded manually by observation and by a Fitbit Zip, attached to the shoe on the dominant or non-affected side. Subgroup analysis included assessment accuracy for those considered limited community walkers (slower than 0.8 m/s) and those considered community walkers (faster than 0.8 m/s). RESULTS: The Fitbit significantly (P < 0.05) undercounted steps compared to manual step count, indoors and outdoors, with percentage agreement slightly higher outdoors (mean 92.4%) than indoors (90.1%). Overall, there was excellent consistent agreement between the Fitbit and manual step count for both indoor (ICC 0.83) and outdoor (ICC 0.88) walks. The accuracy of the Fitbit was significantly (P < 0.05) reduced in those who walked slower than 0.8 m/s outdoors (ICC 0.80) compared to those who walk faster than 0.8 m/s (ICC 0.90). CONCLUSIONS: The Fitbit Zip shows high step count accuracy with manual step count in a mixed subacute rehabilitation population. However, accuracy is affected by walking speed, with decreased accuracy in limited community walkers.

Percolation of Ion-Irradiation-Induced Disorder in Complex Oxide Interfaces.

Mastery of order-disorder processes in highly nonequilibrium nanostructured oxides has significant implications for the development of emerging energy technologies. However, we are presently limited in our ability to quantify and harness these processes at high spatial, chemical, and temporal resolution, particularly in extreme environments. Here, we describe the percolation of disorder at the model oxide interface LaMnO3/SrTiO3, which we visualize during in situ ion irradiation in the transmission electron microscope. We observe the formation of a network of disorder during the initial stages of ion irradiation and track the global progression of the system to full disorder. We couple these measurements with detailed structural and chemical probes, examining possible underlying defect mechanisms responsible for this unique percolative behavior.

Photo-exfoliation of MoS2quantum dots from nanosheets: anin situtransmission electron microscopy study.

Fabrication of transition metal dichalcogenide quantum dots (QDs) is complex and requires submerging powders in binary solvents and constant tuning of wavelength and pulsed frequency of light to achieve a desired reaction. Instead of liquid state photoexfoliation, we utilize infrared laser irradiation of free-standing MoS2flakes in transmission electron microscope (TEM) to achieve solid-state multi-level photoexfoliation of QDs. By investigating the steps involved in photochemical reaction between the surface of MoS2and the laser beam, we gain insight into each step of the photoexfoliation mechanism and observe high yield production of QDs, led by an inhomogeneous crystalline size distribution. Additionally, by using a laser with a lower energy than the indirect optical transition of bulk MoS2, we conclude that the underlying phenomena behind the photoexfoliation is from multi-photon absorption achieved at high optical outputs from the laser source. These findings provide an environmentally friendly synthesis method to fabricate QDs for potential applications in biomedicine, optoelectronics, and fluorescence sensing.

The frequency and impact of undiagnosed benign paroxysmal positional vertigo in outpatients with high falls risk.

BACKGROUND: The frequency and impact of undiagnosed benign paroxysmal positional vertigo (BPPV) in people identified with high falls risk has not been investigated. OBJECTIVE: To determine the frequency and impact on key psychosocial measures of undiagnosed BPPV in adult community rehabilitation outpatients identified with a high falls risk. DESIGN: A frequency study with cross-sectional design. SETTING: A Community Rehabilitation Program in Melbourne, Australia. SUBJECTS: Adult community rehabilitation outpatients with a Falls Risk for Older People in the Community Screen score of four or higher. METHODS: BPPV was assessed in 34 consecutive high falls risk rehabilitation outpatients using the Dix-Hallpike test and supine roll test. Participants were assessed for anxiety, depression, fear of falls, social isolation and loneliness using the Hospital Anxiety and Depression Scale, Falls Efficacy Scale-International and De Jong Gierveld 6-Item Loneliness Scale. RESULTS: A total of 18 (53%; 95% confidence interval: 36, 70) participants tested positive for BPPV. There was no significant difference between those who tested positive for BPPV and those who did not for Falls Risk for Older People in the Community Screen scores (P = 0.555), Hospital Anxiety and Depression Scale (Anxiety) scores (P = 0.627), Hospital Anxiety and Depression Scale (Depression) scores (P = 0.368) or Falls Efficacy Scale-International scores (P = 0.481). Higher scores for the De Jong Gierveld 6-Item Loneliness Scale in participants with BPPV did not reach significance (P = 0.056). CONCLUSIONS: Undiagnosed BPPV is very common and associated with a trend towards increased loneliness in adult rehabilitation outpatients identified as having a high falls risk.

Community participation of community dwelling older adults: a cross-sectional study.

BACKGROUND: With the advancing age of the population, and increasing demands on healthcare services, community participation has become an important consideration for healthy ageing. Low levels of community participation have been linked to increased mortality and social isolation. The extent to which community participation has been measured objectively in older adults remains scarce. This study aims to describe where and how older adults participate in the community and determine the feasibility of measurement methods for community participation. METHODS: This observational cross-sectional study obtained data from 46 community dwelling older adults. A combination of Global Positioning Systems (GPS), accelerometry, and self-reported diaries were used over a 7-day monitoring period. Feasibility of methods were determined by calculating the loss of GPS data, questionnaires, and comparison of self-reported locations with GPS co-ordinates. Relationships between community participation, physical activity, social interactions, health related quality of life, sleep quality and loneliness were explored. RESULTS: Older adults took a median (IQR) of 15 (9.25-18.75) trips out of home over the 7-day monitoring period, most frequently visiting commercial and recreational locations. In-home activities were mainly sedentary in nature, with out of home activities dependent on location type. Self-reported and GPS measures of trips out of home and the locations visited were significantly correlated (self-report 15.7 (5.6) GPS 14.4 (5.8) (r = 0.94)). Significant correlations between both the number of trips taken from home, with social interactions (r = 0.62) and the minutes of moderate to vigorous physical activity (MVPA) (r = 0.43) were observed. Daily MVPA was higher in participants who visited local walk/greenspaces (r = 0.48). CONCLUSION: Participants performed more activities with social interactions out of home and visited commercial locations most frequently. The combination of GPS, accelerometry and self-report methods provided a detailed picture of community participation for older adults. Further research is required with older adults of varying health status to generalise the relationships between community participation, location and physical activity. TRIAL REGISTRATION: Ethical approval was gained from the Flinders University Social and Behavioural Research Ethics Committee (protocol no. 8176).

Ductile Metallic Glass Nanoparticles via Colloidal Synthesis.

The design of ductile metallic glasses has been a longstanding challenge. Here, we use colloidal synthesis to fabricate nickel-boron metallic glass nanoparticles that exhibit homogeneous deformation at room temperature and moderate strain rates. In situ compression testing is used to characterize the mechanical behavior of 90-260 nm diameter nanoparticles. The force-displacement curves consist of two regimes separated by a slowly propagating shear band in small, 90 nm particles. The propensity for shear banding decreases with increasing particle size, such that large particles are more likely to deform homogeneously through gradual shape change. We relate this behavior to differences in composition and atomic bonding between particles of different size using mass spectroscopy and XPS. We propose that the ductility of the nanoparticles is related to their internal structure, which consists of atomic clusters made of a metalloid core and a metallic shell that are connected to neighboring clusters by metal-metal bonds.

In Situ Transmission Electron Microscopy for Ultrahigh Temperature Mechanical Testing of ZrO2.

This work demonstrates a novel approach to ultrahigh-temperature mechanical testing using a combination of in situ nanomechanical testing and localized laser heating. The methodology is applied to characterizing and testing initially nanograined 10 mol % Sc2O3-stabilized ZrO2 up to its melting temperature. The results suggest that the low-temperature strength of nanograined, d < 50 nm, oxides is not influenced by creep. Tensile fracture of ZrO2 bicrystals produce a weak-temperature dependence suggesting that grain boundary energy dominates brittle fracture of grain boundaries even at high homologous temperatures; for example, T = 2050 °C or T ≈ 77% Tmelt. The maximum temperature for mechanical testing in this work is primarily limited by the instability of the sample, due to evaporation or melting, enabling a host of new opportunities for testing materials in the ultrahigh-temperature regime.

Towards a Clinical Decision-Making Algorithm Guiding Locomotor Therapy Modality in Subacute Stroke: An Exploratory Study.

OBJECTIVES: To propose a clinical decision-making algorithm guiding modality choice and transition from the Lokomat® robotic to body-weight supported treadmill training in subacute stroke, due to current evidence being limited, making clinical decisions difficult. MATERIALS AND METHODS: For 10 adult patients with subacute stroke completing Lokomat® therapy, physiotherapist clinical judgement regarding body-weight supported treadmill training readiness and the following objective measurements were collected; Functional Ambulation Category; sit to stand/standing ability; Lokomat® settings; maximal active hip and knee flexion in standing; and gait biomechanics during body-weight supported treadmill training. Based on observed patterns a proposed clinical decision-making algorithm was developed. RESULTS: Clinical judgement deemed four of 10 participants ready to transition to body-weight supported treadmill training. Unlike participants judged not ready, these participants had: a) a Functional Ambulation Category of 1; b) independence with sit to stand and standing with even weight bearing; c) Lokomat®: Body-Weight Support <30%, Guidance Force <30-35%, speed >2.0kph; d) >45° standing active hip and knee flexion; e) no significant issues with physiological stepping in treadmill training or only requiring assistance from one therapist to achieve this. CONCLUSION: Participants judged ready for transition from the Lokomat® to body-weight supported treadmill training presented with increased independent functional ability, more challenging Lokomat® settings, greater active volitional lower-limb control, and less issues with physiological stepping in treadmill training, than those participants judged not ready. Results were translated into a proposed clinical decision-making algorithm guiding transition from the Lokomat® to body-weight supported treadmill training, to be further tested in clinical trials.

Augmented Performance Feedback during Robotic Gait Therapy Results in Moderate Intensity Cardiovascular Exercise in Subacute Stroke.

BACKGROUND: Low cardiovascular fitness is common poststroke. Conventional subacute stroke rehabilitation does not meet Australian National Stroke Guidelines for cardiovascular exercise, particularly in mobility-dependent patients. Walking robotics can potentially achieve recommended cardiovascular exercise with these patients. AIM: The primary aim was to determine whether sustained moderate intensity cardiovascular exercise can be achieved using 3 Lokomat Augmented Performance Feedback activities in mobility-dependent adults with subacute stroke. Secondary aims were to assess if cardiovascular workload was influenced by the activity completed, participants motivation or enjoyment, or changes in Lokomat settings. METHODS: Ten patients with subacute stroke (mean (SD) age: 63.4 (13) years) participated in 6x20-minute Lokomat study sessions. Each study session involved a warm-up and 3x5-minute APF activities presented in a random order. Metabolic data were collected using the COSMED-K5. Participants rated their perceived exertion on the BORG CR10 scale and Lokomat settings of body-weight support, guidance force, and speed were recorded. RESULTS: Moderate intensity cardiovascular exercise was achieved and maintained over the 15 minutes of exercise, objectively demonstrated by a mean (SD) Metabolic Equivalent Task of 3.1 (1.3), and mean (SD) oxygen consumption of 8.0 (3.8) ml/kg/min, estimated as 52% VO2max. This was subjectively confirmed by exertion scores between 3 and 5. The cardiovascular workload was not affected by which activity was completed, participant motivation or enjoyment, or significant progression of Lokomat settings between study sessions. CONCLUSIONS: Mobility-dependent patients with subacute stroke can achieve sustained moderate intensity cardiovascular exercise on the Lokomat when using APF activities.

Pedometers alone do not increase mobility in inpatient rehabilitation: a randomized controlled trial.

OBJECTIVE: To test if pedometers, as a motivational tool, could affect mobility outcomes in inpatient rehabilitation. DESIGN: Randomized controlled clinical trial. SETTING: Subacute hospital rehabilitation unit in Australia. PARTICIPANTS: A total of 78 participants with reduced mobility and clinician-determined capacity to improve. INTERVENTIONS: Both groups received usual care. For the intervention group, a pedometer was worn on the hip with the step count visible to participant and recorded daily on an exercise log. For the control group, a pedometer fixed shut was worn on the hip and they recorded estimated distances walked on an exercise log. MAIN MEASURES: Primary outcome was functional mobility - De Morton Mobility Index. Secondary outcome measures were walking velocity, functional independence measure, time spent upright and daily step count. RESULTS: Significant improvements over time (P < 0.001) in functional mobility, comfortable walking velocity and functional independence measure were not influenced by the intervention. The daily average upright time (hours) in the first week of intervention was different (P = 0.004) between the intervention group (median, interquartile range (IQR): 1.67, 1.77) compared to the control group (median, IQR: 1.12, 0.82). CONCLUSION: Pedometers as a motivational tool without targets do not improve functional mobility in this population. Pedometers may improve daily upright time in this setting.

KdgF, the missing link in the microbial metabolism of uronate sugars from pectin and alginate.

Uronates are charged sugars that form the basis of two abundant sources of biomass-pectin and alginate-found in the cell walls of terrestrial plants and marine algae, respectively. These polysaccharides represent an important source of carbon to those organisms with the machinery to degrade them. The microbial pathways of pectin and alginate metabolism are well studied and essentially parallel; in both cases, unsaturated monouronates are produced and processed into the key metabolite 2-keto-3-deoxygluconate (KDG). The enzymes required to catalyze each step have been identified within pectinolytic and alginolytic microbes; yet the function of a small ORF, kdgF, which cooccurs with the genes for these enzymes, is unknown. Here we show that KdgF catalyzes the conversion of pectin- and alginate-derived 4,5-unsaturated monouronates to linear ketonized forms, a step in uronate metabolism that was previously thought to occur spontaneously. Using enzyme assays, NMR, mutagenesis, and deletion of kdgF, we show that KdgF proteins from both pectinolytic and alginolytic bacteria catalyze the ketonization of unsaturated monouronates and contribute to efficient production of KDG. We also report the X-ray crystal structures of two KdgF proteins and propose a mechanism for catalysis. The discovery of the function of KdgF fills a 50-y-old gap in the knowledge of uronate metabolism. Our findings have implications not only for the understanding of an important metabolic pathway, but also the role of pectinolysis in plant-pathogen virulence and the growing interest in the use of pectin and alginate as feedstocks for biofuel production.

A pilot study: Can the UFOV assessment be used as a repeated measure to determine timing of on-road assessment in stroke?

BACKGROUND/AIMS: Useful Field of View scores are predictive of on-road performance post-stroke. No objective data exist to determine if the Useful Field of View (UFOV) assessment can be used as a repeated measure in the post-stroke population to determine timing of occupational therapy on-road assessment as recovery occurs. The aims of this study were to determine whether there is a practice effect if the UFOV is administered at one, two and three months' post-stroke and to assess optimal time post-stroke to refer to an on-road assessment. METHOD: Forty-two participants, 17 men (40.5%), with a mean age of 71 years (SD 9.33) were randomly allocated to 1. Assessment group - UFOV at one, two and three months' post-stroke, 2. Control group-UFOV at three months' post-stroke. Parametric and non-parametric tests were utilised depending on data distribution. RESULTS: No significance was found between; three months' subtest 1 (P = 0.463), three months' subtest 2 (P = 0.729) and three months' subtest 3 (P = 0.534) between the assessment and control groups. Both group's scores were combined to examine pass/fail rates of UFOV assessment to indicate timing of referral to on-road assessments. At one month, 16.9% stroke survivors passed the UFOV, when reassessed at three months 69.1% passed and 28.6% again failed. CONCLUSION: Improvements in scores at one month intervals over three months are due to improvements in abilities assessed by the UFOV as no practice effect was found to influence scores. UFOV scores performed at monthly intervals post-stroke can be used to guide the timing of an occupational therapy on-road assessment, with an increased likelihood of passing, as recovery occurs. This repeated use of the UFOV assessment can assist referral practices that best utilise driving rehabilitation programmes. Larger studies need to be conducted to confirm these results.

Does purpose in life or ethnic identity moderate the association for racial discrimination and suicide ideation in racial/ethnic minority emerging adults?

OBJECTIVE: To examine purpose in life (PIL) and ethnic identity (EI) as buffers to suicide ideation for Asian American, Hispanic, and Black emerging adults who perceive racial discrimination. METHOD: Two-hundred eighty-nine undergraduate students enrolled at a large university in the southwestern region of the United States (40.8% Asian American, 32.5% Hispanic, 26.6% Black; 61.2% women; mean age = 20.47, SD = 1.83) reported on experiences of racial discrimination, PIL, EI, and suicidal thoughts. Covariates were intrinsic religiosity, gender, and age. RESULTS: Regression analysis showed that EI was not a significant moderator for the association between perceived racial discrimination (PRD) and suicidal ideation (ß = -.08, p = .13; 95% confidence interval (CI) [-.19, .03]). However, PIL was a significant moderator (ß = -.11, p = .025; CI [-.20, -.01]). A hierarchical regression showed that PIL as a moderator explained additional variance (ΔR2 = 0.11, p < .001) in suicide ideation above and beyond EI. CONCLUSIONS: These findings provide some insight into how life purpose might ameliorate the impact of social stressors above and beyond a positive cultural identity for young racial/ethnic minority adults. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Traumatic brain injury and post-traumatic amnesia: a retrospective review of discharge outcomes.

PRIMARY OBJECTIVE: To investigate if patients with traumatic brain injury, who are discharged to the community before emergence from post-traumatic amnesia (PTA), experience more adverse outcomes than those discharged after emergence from PTA. RESEARCH DESIGN: A retrospective review of previously collected data and medical records. METHODS AND PROCEDURES: Occurrences of adverse events including hospital readmissions, disengagement from follow-up services, non-compliance with discharge precautions, support system breakdown or undue carer strain at the post-discharge clinic review were recorded. The Glasgow Outcome Scale - Extended (GOS-E) and Supervision Rating Scale (SRS) were completed, retrospectively. Twenty-seven patients discharged to the community, prior to emergence from PTA, were compared to 20 patients discharged within seven days of emergence from PTA. MAIN OUTCOMES AND RESULTS: Patients discharged prior to emergence from PTA did not experience an increase in adverse outcomes and showed a higher level of engagement in follow-up services (p = 0.015). There was no difference between groups in the improvements from discharge to clinic review on the GOS-E (p = 0.113) and SRS (p = 0.165). CONCLUSIONS: Patients can be discharged prior to emergence from PTA, if all other discharge criteria have been met, without an increase in adverse outcomes.

A composite likelihood approach for estimating HIV prevalence in the presence of spatial variation.

Since 1990, the World Health Organization has recommended HIV surveillance among pregnant women as an essential surveillance activity for countries with generalized HIV epidemics. Despite the widespread availability and potential usefulness of antenatal HIV surveillance, analyses of such data present important challenges. Within an individual clinic, the HIV status of its attendees may be correlated because of similarities in HIV risk among women close in age. Between-clinic correlation may also arise as women often seek antenatal care at clinics located close to their home, and individuals living in nearby communities may share important characteristics or behaviours related to susceptibility. A general estimating equation-based approach for spatially-correlated, binary data such as that antenatal HIV surveillance based on a pairwise composite likelihood has been described. We present an extended version of this model that can accommodate penalized spline estimators and apply it to antenatal HIV surveillance data collected in 2011 in Botswana to estimate the effects of proximity to the 'hotspot' of the country's HIV epidemic and age on HIV prevalence. Finally, we compare the results with a logistic regression analysis, which ignores potential correlation of responses.

Assessing gait variability in transtibial amputee fallers based on spatial-temporal gait parameters normalized for walking speed.

OBJECTIVE: To determine whether normalizing spatial-temporal gait data for walking speed obtained from multiple walking trials leads to differences in gait variability parameters associated with a history of falling in people with transtibial amputations. DESIGN: Cross-sectional study. SETTING: Rehabilitation center. PARTICIPANTS: People with unilateral transtibial amputations (N=45; mean age ± SD, 60.5±13.7y; 35 men [78%]) were recruited. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Participants completed 10 consecutive walking trials using an instrumented walkway system. Primary gait parameters were walking speed and step-length, step-width, step-time, and swing-time variability. A retrospective 12-month fall history was obtained from participants. RESULTS: Sixteen amputees (36%) were classified as fallers. Variation in gait speed across the 10 walking trials was 2.9% (range, 1.1%-12.1%). Variability parameters of normalized gait data were significantly different from variability parameters of nonnormalized data (all P<.01). For nonnormalized data, fallers had greater amputated limb step-time (P=.02), step-length (P=.02), swing-time (P=.05), and step-width (P=.03) variability and nonamputated limb step-length (P=.04) and step-width (P=.01) variability. For normalized data, only 3 variability parameters were significantly greater for fallers. These were amputated limb step-time (P=.05), step-length (P=.02), and step-width (P=.01) variability. CONCLUSIONS: Normalizing spatial-temporal gait data for walking speed before calculating gait variability parameters may aid in discerning variability parameters related to falls histories in people with transtibial amputations. This may help focus on the initial rehabilitation efforts of amputees with a fall history.

Dorsiflexion assist orthosis reduces the physiological cost and mitigates deterioration in strength and balance associated with walking in people with multiple sclerosis.

OBJECTIVE: To evaluate the effect of wearing a dorsiflexion assist orthosis (DAO) on walking distance, physiological cost, fatigue, and strength and balance measures after a modified 6-minute walk test (6MWT) in people with multiple sclerosis (MS). DESIGN: Randomized crossover trial. SETTING: Hospital Movement Laboratory. PARTICIPANTS: People with moderate MS and Expanded Disability Status Scale score of 3.7±0.7 (N=34; 26 women). INTERVENTIONS: Modified 6MWT with and without a DAO worn on the weaker leg. MAIN OUTCOME MEASURES: Distance walked, perceived fatigue, and the physiological cost of walking were compared between walking conditions. Pre- and postwalk changes in knee extensor and ankle dorsiflexor isometric strength and standing postural sway with eyes open and closed were compared between walking conditions. RESULTS: There were no differences in distance walked or perceived fatigue between the 2 walking conditions. However, there was a reduced physiological cost of walking (P<.05), a smaller reduction in knee extensor strength (P<.05), and a smaller increase in standing postural sway with eyes open (P<.01) after walking while wearing the DAO compared with walking without wearing the DAO. CONCLUSIONS: Despite not increasing walking distance or reducing perceived fatigue, the DAO reduced the physiological cost of walking and maintained knee strength and standing balance, which may have important implications for physical rehabilitation in people with MS. Further trials are required to determine whether the beneficial effects of wearing a DAO found here are maintained for longer periods.

Over ground walking and body weight supported walking improve mobility equally in cerebral palsy: a randomised controlled trial.

OBJECTIVE: To assess partial body weight supported treadmill training versus over ground training for walking ability in children with mild to moderate cerebral palsy. DESIGN: Randomised controlled trial. SETTING: A Special Needs school in Singapore. SUBJECTS: Thirty children with cerebral palsy, aged 6-18, with a Gross Motor Function Classification System score of II-III. INTERVENTIONS: Two times 30 minute sessions of walking training per week for 8 weeks, progressed as tolerated, either over ground (control) or using partial body weight supported treadmill training (intervention). MAIN MEASURES: The 10 metre walk test, and the 6 minute walk test. Secondary measures were sub-sections D and E on the Gross Motor Function Measure. Outcomes were assessed at baseline, and after 4 and 8 weeks of training. RESULTS: There was no effect of group allocation on any outcome measure, while time was a significant factor for all outcomes. Walking speed improved significantly more in the intervention group by week 4 (0.109 (0.067)m/s vs 0.048 (0.071)m/s, P=0.024) however by week 8 the change from baseline was similar (intervention 0.0160 (0.069)m/s vs control 0.173 (0.109)m/s, P=0.697). All gains made by week 4 were significantly improved on by week 8 for the 10 metre walk test, 6 minute walk test, and the gross motor function measure. CONCLUSIONS: Partial body weight supported treadmill training is no more effective than over ground walking at improving aspects of walking and function in children with mild to moderate cerebral palsy. Gains seen in 4 weeks can be furthered by 8 weeks.