c-axis coupling in underdoped Bi(2)Sr(2)CaCu(2)O(8+δ) with varying degrees of disorder

c-axis coupling in underdoped Bi(2)Sr(2)CaCu(2)O(8+δ) with varying degrees of disorde

Automatic recognition of falls in gait-slip training: Harness load cell based criteria

Over-head-harness systems, equipped with load cell sensors, are essential to the participants' safety and to the outcome assessment in perturbation training. The purpose of this study was to first develop an automatic outcome recognition criterion among young adults for gait-slip training and then verify such criterion among older adults. Each of 39 young and 71 older subjects, all protected by safety harness, experienced 8 unannounced, repeated slips, while walking on a 7 m walkway. Each trial was monitored with a motion capture system, bilateral ground reaction force (GRF), harness force, and video recording. The fall trials were first unambiguously indentified with careful visual inspection of all video records. The recoveries without balance loss (in which subjects' trailing foot landed anteriorly to the slipping foot) were also first fully recognized from motion and GRF analyses. These analyses then set the gold standard for the outcome recognition with load cell measurements. Logistic regression analyses based on young subjects' data revealed that the peak load cell force was the best predictor of falls (with 100% accuracy) at the threshold of 30% body weight. On the other hand, the peak moving average force of load cell across 1 s period, was the best predictor (with 100% accuracy) separating recoveries with backward balance loss (in which the recovery step landed posterior to slipping foot) from harness assistance at the threshold of 4.5% body weight. These threshold values were fully verified using the data from older adults (100% accuracy in recognizing falls). Because of the increasing popularity in the perturbation training coupling with the protective over-head-harness system, this new criterion could have far reaching implications in automatic outcome recognition during the movement therapy

Alteration in community-dwelling older adults' level walking following perturbation training

While perturbation training is promising in reducing fall-risk among older adults, its impact on altering their spontaneous gait pattern has not been investigated. The purpose of this study was to determine to what extent older adults’ gait pattern would be affected by exposure to 24 repeated slips. Seventy-three community-dwelling older adults (age: 72.6 ± 5.4 years) underwent 24 repeated-slip exposure induced by unannounced unlocking and relocking of low-friction sections of a 7-m pathway upon which they walked. Full body kinematics and kinetics were recorded during the training. The gait parameters and the center of mass (COM) stability against backward balance loss were compared before and after the training. The results revealed that the training reduced fall incidence from 43.8% upon the novel slip to 0 at the end of training. After the training, subjects significantly improved gait stability by forward positioning of their COM relative to the base of support without altering gait speed. This forward COM shift resulted from a shortened step at the end of single stance and forward trunk leaning during double stance. They also adopted flat foot landing with knee flexed at touchdown (with an average change of 6.9 and 4.1 degrees, respectively). The perturbation training did alter community-dwelling older adults’ spontaneous gait pattern. These changes enabled them to improve their volitional control of stability and their resistance to unpredictable and unpreventable slip-related postural disturbance

Obesity May Not Induce Dynamic Stability Disadvantage during Overground Walking among Young Adults - Fig 2

<p>Group mean (column height) and standard deviation (error bar) of the elapsed time in seconds for both normal-weight (or Normal) and obese (or Obese) groups of (a) double and single stance phases and (b) the step time, defined as the duration from touchdown of one foot to the following touchdown of the contralateral foot (i.e., the sum of the single and double phases). Also shown are the percentages of the single stance and double stance with respect to the gait cycle.</p

Demographic information in mean ± standard deviation for both normal-weight (or Normal, <i>n</i> = 21) and obese (or Obese, <i>n</i> = 23) groups.

<p>Demographic information in mean ± standard deviation for both normal-weight (or Normal, <i>n</i> = 21) and obese (or Obese, <i>n</i> = 23) groups.</p

The comparison of the trunk angle at two transient gait events (touchdown or TD and liftoff or LO) between normal-weight and obese groups.

<p>Trunk angle was calculated between the trunk segment and a vertical axis. Positive trunk angle represents that the trunk leans backward against the vertical line while zero means the trunk is in a neutral position which aligns perfectly with the vertical axis.</p

Reactive Control and its Operation Limits in Responding to a Novel Slip in Gait

Abstract The purposes of this study were: (1) to examine the reactive control of the resultant joint moments at the lower limbs in response to a novel and unannounced slip; (2) to establish individualized forward-dynamics models; and (3) to explore personal potential by determining the operation limits of these moments at each lower limb joint, beyond which the resulting motion at this or other joints will exceed its/their normal range(s). Ten young subjects’ kinematics and kinetics, collected during regular walking and during their first exposure to a novel and unannounced slip, were randomly selected from an existing database. An inverse-dynamics approach was applied to derive their (original) resultant joint moments, which were then used as input to establish forward-dynamics models, each including an individualized 16-element foot model to simulate ground reaction force. A simulated annealing (SA) algorithm was applied to modify the original moments, so that the subsequent output (baseline) moments can closely reproduce these subjects’ recorded motion. A systematic alteration of the baseline moments was employed to determine the operation limits. The results revealed that the subjects reactively increased the hip extensor and knee flexor moments and reduced their ankle plantar flexor moments of their single-stance limb following slip onset. The “baseline” correction of the original moments can reach as much as 21% of the original moments. The analysis of the operation limits revealed that these individuals may be able to further increase their knee flexors more so than increase the hip extensors or reduce ankle plantar flexors before causing abnormal joint movement. Such systematic approach opens the possibility to properly assess an individual’s rehabilitation potential, and to identify whether this person’s strength is the limiting factor for stability training

The feasible stability region.

<p>The illustration showing the feasible stability region (FSR) which is bounded by two borders: the limit against backward balance loss (the lower boundary) and the one against forward balance loss (the upper boundary). The stability measurement (<i>s</i>, the length of the thin solid line) indicates the magnitude of the instantaneous stability of the center of mass (COM) against backward balance loss, and is calculated as the shortest distance from the instantaneous COM motion state (i.e., the <i>x</i>- and <i>y</i>-coordinates represents the COM anteroposterior position and velocity, respectively) to the limit against backward balance loss. Also shown is a representative COM motion state trajectory of an overground walking (the thin line) progressing from the touchdown (TD, filled circle), through the contralateral foot liftoff (LO, square), and immediately prior to the contralateral foot TD (open circle). Position and velocity of the COM relative to the base of support (BOS) are <i>dimensionless</i> as a fraction of <i>l</i>_<i>BOS</i> and , respectively, where <i>l</i>_<i>BOS</i> represents the foot length, <i>g</i> is gravitational acceleration, and <i>bh</i> the body height. When the COM motion state is outside the FSR, the person is either backward instable (below the limit against backward balance loss) or forward instable (above the limit against forward balance loss). A recovery step becomes necessary to keep the person from falling either backward or forward.</p

Serum level changes of BTMs during the chemotherapy process.

<p>Values were presented as mean± SD.</p><p>*Statistically significant at P < 0.05.</p><p>25(OH)D, 25-hydroxvitamin D; PTH, parathyroid hormone; E2, estradiol; FSH, follicle-stimulating hormone.</p><p>C₀, the day of initial diagnosis before chemotherapy;</p><p>C₁, 24 hours after the first cycle of chemotherapy;</p><p>C₂, 24 hours after the second cycle of chemotherapy;</p><p>C₃, 24 hours after the third cycle of chemotherapy;</p><p>C₄, 24 hours after the fourth cycle of chemotherapy.</p><p>P^a: comparison between the healthy control and the baseline of patients;</p><p>P^b: comparison between the baseline (C₀) and after the 4th cycle of chemotherapy (C₄).</p><p>Serum level changes of BTMs during the chemotherapy process.</p

Changes of serum bone turnover markers levels under different cycles of chemotherapy in post-menopausal breast cancers.

<p>(*) p< 0.05; (**) p<0.01. C0: the day of initial diagnosis; C1–C4: 24 hours after the first, second, third. Fourth cycle of chemotherapy.</p