A GPU Stream Computing Approach to Terrain Database Integrity Monitoring

Synthetic Vision Systems (SVS) provide an aircraft pilot with a virtual 3-D image of surrounding terrain which is generated from a digital elevation model stored in an onboard database. SVS improves the pilot\u27s situational awareness at night and in inclement weather, thus reducing the chance of accidents such as controlled flight into terrain. A terrain database integrity monitor is needed to verify the accuracy of the displayed image due to potential database and navigational system errors. Previous research has used existing aircraft sensors to compare the real terrain position with the predicted position. We propose an improvement to one of these models by leveraging the stream computing capabilities of commercial graphics hardware. Brook for GPUs, a system for implementing stream computing applications on programmable graphics processors, is used to execute a streaming ray-casting algorithm that correctly simulates the beam characteristics of a radar altimeter during all phases of flight

Spatiotemporal postural control deficits are present in those with chronic ankle instability

BACKGROUND: Postural control deficits have been purported to be a potential contributing factor in chronic ankle instability (CAI). Summary forceplate measures such as center of pressure velocity and area have not consistently detected postural control deficits associated with CAI. A novel measurement technique derived from the dynamical systems theory of motor control known as Time-to-boundary (TTB) has shown promise in detecting deficits in postural control related to chronic ankle instability (CAI). In a previous study, TTB deficits were detected in a sample of females with CAI. The purpose of this study was to examine postural control in sample of males and females with and without CAI using TTB measures. METHODS: This case-control study was performed in a research laboratory. Thirty-two subjects (18 males, 14 females) with self-reported CAI were recruited and matched to healthy controls. All subjects performed three, ten-second trials of single-limb stance on a forceplate with eyes open and eyes closed. Main outcome measures included the TTB absolute minimum (s), mean of TTB minima (s), and standard deviation of TTB minima (s) in the anteroposterior and mediolateral directions. A series of group by gender analyses of variance were conducted to evaluate the differences in postural control for all TTB variables separately with eyes open and eyes closed. RESULTS: There were no significant group by gender interactions or gender main effects for any of the measures. There, however, significant group main effects for 4 of the 6 measures with eyes closed as the CAI group demonstrated significant deficits in comparison to the control group. There were no significant differences between groups in any of the TTB measures with eyes open. CONCLUSION: TTB deficits were present in the CAI group compared to the control group. These deficits were detected with concurrent removal of visual input. CAI may place significantly greater constraints on the sensorimotor system during single limb stance, resulting in a reorganization of postural control strategies. These deficits may be indicative of a diminished ability to respond effectively to changes in postural control demands in those with CAI

Two-week joint mobilization intervention improves self-reported function, range of motion, and dynamic balance in those with chronic ankle instability

We examined the effect of a 2-week anterior-to-posterior ankle joint mobilization intervention on weight-bearing dorsiflexion range of motion (ROM), dynamic balance, and self-reported function in subjects with chronic ankle instability (CAI). In this prospective cohort study, subjects received six Maitland Grade III anterior-to-posterior joint mobilization treatments over 2 weeks. Weightbearing dorsiflexion ROM, the anterior, posteromedial, and posterolateral reach directions of the Star Excursion Balance Test (SEBT), and self-reported function on the Foot and Ankle Ability Measure (FAAM) were assessed 1 week before the intervention (baseline), prior to the first treatment (pre-intervention), 24–48 h following the final treatment (post-intervention), and 1 week later (1-week follow-up) in 12 adults (6 males and 6 females) with CAI. The results indicate that dorsiflexion ROM, reach distance in all directions of the SEBT, and the FAAM improved (p < 0.05 for all) in all measures following the intervention compared to those prior to the intervention. No differences were observed in any assessments between the baseline and pre-intervention measures or between the postintervention and 1-week follow-up measures (p > 0.05). These results indicate that the joint mobilization intervention that targeted posterior talar glide was able to improve measures of function in adults with CAI for at least 1 week

Peroneal Reaction Time After Ankle Sprain: A Systematic Review and Meta-Analysis

Background: Many studies have examined the temporal response of the peroneal muscles to sudden inversion perturbation in patients with a previous ankle sprain. The purpose of this systematic review with meta-analysis was to synthesize the evidence and determine whether peroneal reaction time (PRT) impairments are present after ankle sprain. Methods: An electronic search was conducted using PubMed Central and EBSCOhost (1965-January 2013). Articles were included if they 1) examined the PRT to sudden inversion perturbation in patients with a history of ankle sprain using a mechanical tilt platform, 2) made comparisons with a control group or contralateral limb with no history of ankle sprain, and 3) provided data for the calculation of effect sizes (ES). In addition to examining the overall effect of sustaining an ankle sprain on PRT, the effects of study design and subject characteristics on PRT were evaluated. Bias-corrected Hedges g ES and 95% confidence intervals (CI) were calculated to make comparisons across studies. Results: A total of 23 studies met the inclusion criteria. The overall ES was 0.67 (95% CI = 0.37-0.95, P \u3c 0.001), indicating that a previous ankle sprain, regardless of study design or subject characteristics, resulted in moderate-to-strong PRT deficits. Further analyses determined studies with patients classified as having chronic ankle instability demonstrated large magnitude PRT deficits in between groups (ES = 0.72, 95% CI = 0.29-1.14, P = 0.001) and side-to-side (ES = 1.24, 95% CI = 0.70-1.79, P \u3c 0.001) comparisons, whereas patients with all other ankle sprain histories demonstrated weak PRT alterations in between groups (ES = -0.21, 95% CI = -1.01 to 0.59, P = 0.61) and side-to-side (ES = 0.21, 95% CI = -0.19 to 0.60, P = 0.31) comparisons. Conclusions: Overall, this meta-analysis determined that individuals with a previous ankle sprain exhibit delayed PRT. Further analyses determined that these deficits are more evident in patients with chronic ankle instability when compared with the contralateral uninvolved limb or a healthy control group

Sensory-Targeted Ankle Rehabilitation Strategies for Chronic Ankle Instability

Deficient sensory input from damaged ankle ligament receptors is thought to contribute to sensorimotor deficits in those with chronic ankle instability (CAI). Targeting other viable sensory receptors may then enhance sensorimotor control in these patients. The purpose of this randomized controlled trial was to evaluate the effects of 2 weeks of sensory-targeted rehabilitation strategies (STARS) on patient- and clinician-oriented outcomes in those with CAI

Predicting Manual Therapy Treatment Success in Patients With Chronic Ankle Instability: Improving Self-Reported Function

CONTEXT: Therapeutic modalities that stimulate sensory receptors around the foot-ankle complex improve chronic ankle instability (CAI)-associated impairments. However, not all patients have equal responses to these modalities. Identifying predictors of treatment success could improve clinician efficiency when treating patients with CAI. OBJECTIVE: To conduct a response analysis on existing data to identify predictors of improved self-reported function in patients with CAI. DESIGN: Secondary analysis of a randomized controlled clinical trial. SETTING: Sports medicine research laboratories. PATIENTS OR OTHER PARTICIPANTS: Fifty-nine patients with CAI, which was defined in accordance with the International Ankle Consortium recommendations. INTERVENTION(S): Participants were randomized into 3 treatment groups (plantar massage [PM], ankle-joint mobilization [AJM], or calf stretching [CS]) that received six 5-minute treatments over 2 weeks. MAIN OUTCOME MEASURE(S): Treatment success, defined as a patient exceeding the minimally clinically important difference of the Foot and Ankle Ability Measure-Sport (FAAM-S). RESULTS: Patients with ≤5 recurrent sprains and ≤82.73% on the Foot and Ankle Ability Measure had a 98% probability of having a meaningful FAAM-S improvement after AJM. As well, ≥5 balance errors demonstrated 98% probability of meaningful FAAM-S improvements from AJM. Patients <22 years old and with ≤9.9 cm of dorsiflexion had a 99% probability of a meaningful FAAM-S improvement after PM. Also, those who made ≥2 single-limb-stance errors had a 98% probability of a meaningful FAAM-S improvement from PM. Patients with ≤53.1% on the FAAM-S had an 83% probability of a meaningful FAAM-S improvement after CS. CONCLUSIONS: Each sensory-targeted ankle-rehabilitation strategy resulted in a unique combination of predictors of success for patients with CAI. Specific indicators of success with AJM were deficits in self-reported function, single-limb balance, and <5 previous sprains. Age, weight-bearing-dorsiflexion restrictions, and single-limb balance deficits identified patients with CAI who will respond well to PM. Assessing self-reported sport-related function can identify CAI patients who will respond positively to CS

Assessment of neuromuscular and haemodynamic activity in individuals with and without chronic low back pain

BACKGROUND: Biering-Sørenson (1984) found that individuals with less lumbar extensor muscle endurance had an increased occurrence of first episode low back pain. As a result, back endurance tests have been recommended for inclusion in health assessment protocols. However, different studies have reported markedly different values for endurance times, leading some researchers to believe that the back is receiving support from the biceps femoris and gluteus maximus. Therefore, this study was designed to examine the haemodynamic and neuromuscular activity of the erector spinae, biceps femoris, and gluteus maximus musculature during the Biering-Sørenson Muscular Endurance Test (BSME). METHODS: Seventeen healthy individuals and 46 individuals with chronic low back pain performed the Biering-Sørenson Muscular Endurance Test while surface electromyography was used to quantify neuromuscular activity. Disposable silver-silver-chloride electrodes were placed in a bipolar arrangement over the right or left biceps femoris, gluteus maximus, and the lumbosacral paraspinal muscles at the level of L(3). Near Infrared Spectroscopy was used simultaneously to measure tissue oxygenation and blood volume changes of the erector spinae and biceps femoris. RESULTS: The healthy group displayed a significantly longer time to fatigue (Healthy: 168.5s, LBP: 111.1s; p ≤ 0.05). Significant differences were shown in the median frequency slope of the erector spinae between the two groups at 90–100% of the time to fatigue while no significant differences were noted in the haemodynamic data for the two groups. CONCLUSION: Although the BSME has been recognized as a test for back endurance, individuals with chronic LBP appear to incorporate a strategy that may help support the back musculature by utilizing the biceps femoris and gluteus maximus to a greater degree than their healthy counterparts

Plantar Vibrotactile Detection Deficits in Adults with Chronic Ankle Instability

Purpose: The purpose of this study was to investigate the vibrotactile detection thresholds of the plantar cutaneous afferents in subjects with chronic ankle instability compared with healthy control subjects. Methods: Eight adults with chronic ankle instability and eight adults with no ankle sprain history participated. Vibrotactile detection thresholds were assessed using a mechanical stimulus generator system, mounted onto an articulated microscope arm, which delivered sinusoidal vibrotactile inputs to the foot sole at three different sites: head of the first metatarsal, base of the fifth metatarsal, and the heel. Vibrotactile stimulation was delivered at a range of test frequencies that corresponded to the known responsiveness of cutaneous mechanoreceptors in the glabrous skin of the foot sole (10, 25, and 50 Hz). Probe displacement measures (dB) from the last eight displacement trials that contained 50% positive detection responses were averaged to obtain a single threshold estimate for each test frequency and site combination. Results: The results of this study indicate that no significant group-by-site interactions were found for any test frequencies (P \u3e 0.29). However, group main effects were present at the 10-Hz (P \u3c 0.0001), 25-Hz (P = 0.03), and 50-Hz (P = 0.04) test frequencies, indicating that subjects with chronic ankle instability had significantly higher detection thresholds or less sensitivity when stimulation sites were pooled. Conclusions: The results of this study indicate that subjects with chronic ankle instability may demonstrate decreased sensitivity on the plantar surface of the foot. These alterations in plantar cutaneous somatosensation may help explain the underlying mechanisms associated with the prolonged sensorimotor system impairments in postural control and gait commonly exhibited by people with chronic ankle instability

METHODOLOGICAL ISSUES IN QUANTIFYING COORDINATION-VARIABILITY

The aim was to investigate the effects of stride definitions on vector-coding for quantifying coordination-variability between the shank and rearfoot angles for strides extracted from heel-strike (HS) versus toe-off (TO) events. Subjects with chronic ankle instability were randomly assigned to control and balance-training groups (n=31). Three peaks of coordination-variability consistently existed near midswing, midstance and just before HS during treadmill walking at 1.32m/s. Variability only reduced near HS after balance training for the HS to HS stride definition (pre 0.45±0.14; post 0.34±0.12;