Gait patterns during overground and virtual omnidirectional treadmill walking.

BACKGROUND: Omnidirectional treadmills (ODTs) offer a promising solution to the virtual reality (VR) locomotion problem, which describes the mismatch between visual and somatosensory information and contributes to VR sickness. However, little is known about how walking on ODTs impacts the biomechanics of gait. This project aimed to compare overground and ODT walking and turning in healthy young adults. METHODS: Fifteen young adults completed forward walk, 180° turn, and 360° turn tasks under three conditions: (1) overground, (2) on the Infinadeck ODT in a virtual environment without a handrail, and (3) on the ODT with a handrail. Kinematic data for all walking trials were gathered using 3D optical motion capture. RESULTS: Overall, gait speed was slower during ODT walking than overground. When controlling for gait speed, ODT walking resulted in shorter steps and greater variability in step length. There were no significant differences in other spatiotemporal metrics between ODT and overground walking. Turning on the ODT required more steps and slower rotational speeds than overground turns. The addition of the stability handrail to the ODT resulted in decreased gait variability relative to the ODT gait without the handrail. CONCLUSION: Walking on an ODT resembles natural gait patterns apart from slower gait speed and shorter step length. Slower walking and shorter step length are likely due to the novelty of physically navigating a virtual environment which may result in a more conservative approach to gait. Future work will evaluate how older adults and those with neurological disease respond to ODT walking.

Digitizing a Therapeutic: Development of an Augmented Reality Dual-Task Training Platform for Parkinson's Disease.

Augmented reality (AR) may be a useful tool for the delivery of dual-task training. This manuscript details the development of the Dual-task Augmented Reality Treatment (DART) platform for individuals with Parkinson's disease (PD) and reports initial feasibility, usability, and efficacy of the DART platform in provoking dual-task interference in individuals with PD. The DART platform utilizes the head-mounted Microsoft HoloLens2 AR device to deliver concurrent motor and cognitive tasks. Biomechanical metrics of gait and cognitive responses are automatically computed and provided to the supervising clinician. To assess feasibility, individuals with PD (N = 48) completed a bout of single-task and dual-task walking using the DART platform. Usability was assessed by the System Usability Scale (SUS). Dual-task interference was assessed by comparing single-task walking and walking during an obstacle course while performing a cognitive task. Average gait velocity decreased from 1.06 to 0.82 m/s from single- to dual-task conditions. Mean SUS scores were 81.3 (11.3), which placed the DART in the "good" to "excellent" category. To our knowledge, the DART platform is the first to use a head-mounted AR system to deliver a dual-task paradigm and simultaneously provide biomechanical data that characterize cognitive and motor performance. Individuals with PD were able to successfully use the DART platform with satisfaction, and dual-task interference was provoked. The DART platform should be investigated as a platform to treat dual-task declines associated with PD.

An Augmented Reality Rifle Qualification Test for Return-to-Duty Assessment in Service Members.

INTRODUCTION: Variability in return-to-duty (RTD) decision-making following mild traumatic brain injury (mTBI) is a threat to troop readiness. Current RTD assessments lack military-specific tasks and quantitative outcomes to inform stakeholders of a service member's (SM) capacity to successfully perform military duties. Augmented reality (AR), which places digital assets in a user's physical environment, provides a technological vehicle to deliver military-relevant tasks to a SM to be used in the RTD decision-making process. In addition to delivering digital content, AR headsets provide biomechanical data that can be used to assess the integrity of the central nervous system in movement control following mTBI. The objective of this study was to quantify cognitive and motor performance on an AR rifle qualification test (RQT) in a group of neurologically healthy military SMs. MATERIALS AND METHODS: Data were collected from 111 healthy SMs who completed a basic (single-task) and complex (dual-task) RQT with a simulated M4 rifle. The complex scenario required the SM to perform the RQT while simultaneously answering arithmetic problems. Position data from the AR headset were used to capture postural sway, and the built-in microphone gathered responses to the arithmetic problems. RESULTS: There were no differences in the number of targets hit, trigger pull reaction time, and transition time from kneeling to standing between the basic and complex scenarios. A significant worsening in postural sway following kneel-to-stand transition was observed in the complex scenario. The average reaction time to answer the arithmetic problems was nearly 2 times slower than the average reaction time to pull the trigger to a displayed target in the complex scenario. CONCLUSION: The complex scenario provoked dual-task interference in SMs as evidenced by worsening postural sway and reaction time differences between the cognitive and motor tasks. An AR RQT provides objective and quantitative outcomes during a military-specific task. Greater precision in evaluating cognitive and motor performance during a military-relevant task has the potential to aid in the detection and management of SMs and their RTD following MTBI.

Utilizing Augmented Reality to Evaluate Service Member Team Performance.

INTRODUCTION: Decision-making is a complex process that relies on situational awareness and experience to create a potential list of actions while weighing the risks and benefits of each action. There is a paucity of data evaluating decision-making for individual service members (SM) during the performance of team-based military-relevant activities. Understanding individual performance and decision-making within the context of a team-based activity has potential to aid in the detection and management of mild traumatic brain injuries and assist with safe and timely return-to-duty decision making. The aim of this project was to evaluate cognitive and motor performance in healthy SM during an augmented reality military specific, team-based activity. MATERIALS AND METHODS: Data from 110 SMs from Fort Moore Georgia were analyzed for this project. Service members completed 3 augmented reality room breaching and clearing scenarios (Empty Room, Civilian/Combatant, and Incorrect Position of a unit member) with 3 avatar team members. Participants wore a Microsoft HoloLens 2 (HL2) device and used a replica M4 weapon (Haptech Defense Systems) during scenarios. Three-dimensional position data from the HL2 headset was used to compute temporal measures of room breaching and clearing events while the number and timing of weapon discharge was monitored by the M4. Temporal outcomes included time to enter room, time to fire first shot, time in fatal funnel, and total trial time while motor outcomes were distance traveled and average movement velocity. RESULTS: Pairwise comparisons between the Incorrect Position scenario and the Civilian/Combatant scenario demonstrated no difference in time to enter the room (2.36 seconds in both scenarios). Time to fire the first shot in the Civilian/Combatant scenario was longer (0.97 seconds to 0.58 seconds) while time in fatal funnel (2.58 seconds to 3.31 seconds) and time to trial completion (7.46 seconds to 8.41 seconds) were significantly longer in the Incorrect Position scenario. CONCLUSIONS: Reaction time to fire the first shot, time in the fatal funnel, and total trial time reflect a change in information-processing and decision-making capabilities during military specific, ecological, team-based scenarios when altering the environment inside of the room and modifying avatar movements. Future studies are planned to evaluate the effects of mild traumatic brain injury on specific aspects of military team performance.

A Novel Peritoneal Packing Method for Management of Hyperkalemia During Acute Kidney Injury in Trauma.

INTRODUCTION: United States Military operations in resource limited areas are increasing. Furthermore, future peer or near-peer conflicts will require caring for larger numbers of casualties with limited resources. In this setting, traditional renal replacement therapy is not feasible and novel methods are required to address severe acute kidney injury in austere environments lacking definitive therapies. Here, we describe experiments designed to determine the efficacy of a novel peritoneal packing material (Potassium Binding Pack-PBP, CytoSorbents INC) for the acute management of severe hyperkalemia. MATERIALS AND METHODS: Male swine (52 ±1 kg) were nephrectomized via midline laparotomy under a plane of anesthesia and randomized into one of two experimental groups (PBP & CON). Exogenous potassium was infused to achieve a serum potassium level of 7.5 mEq/L. Novel potassium absorbing packs (PBP) or sham packs (CON) were placed in the right and left upper quadrants, and the right and left paracolic gutters of the abdomen to simulate four-quadrant packing (n = 6, n = 5, respectively). Two liters of peritoneal dialysis fluid was instilled into the abdomen and temporary closure performed. Animals were observed for 12 hours. Serum and peritoneal fluid (dialysate) potassium levels were sampled at T = 15, 30, 60 min, and Q60min thereafter. Animals were humanely euthanized at the end of the observation period. RESULTS: Baseline characteristics were similar between groups. Pairwise analysis showed that serum potassium concentrations were significantly lower in the PBP group compared to CON at T = 540 and T = 720 (P = 0.006 and P = 0.015, respectively). Potassium concentrations were significantly lower in dialysate of the PBP group compared to CON at all time points after T = 15 (T = 30, P = 0.017; T = 60 through T = 720, P < 0.001). CONCLUSIONS: This is the first demonstration of an effective technology for the management of hyperkalemia in trauma in the absence of standard of care; renal replacement therapy. We identified that PBP was able to consistently maintain a concentration gradient between dialysate in the peritoneum and system potassium concentration throughout the experiment. Furthermore, systemic potassium concentrations were reduced in a clinically relevant manner in the PBP group compared to CON. This suggests that peritoneal packing technology for the management of metabolic disturbances in trauma has potential for clinical application. These results are preliminary and should be interpreted with caution.

A Randomized Clinical Trial to Evaluate a Digital Therapeutic to Enhance Gait Function in Individuals With Parkinson's Disease.

BACKGROUND: Postural instability and gait dysfunction (PIGD) is a cardinal symptom of Parkinson's disease (PD) and is exacerbated under dual-task conditions. Dual-task training (DTT), enhances gait performance, however it is time and cost intensive. Digitizing DTT via the Dual-task Augmented Reality Treatment (DART) platform can expand the availability of an effective intervention to address PIGD. OBJECTIVE: The aim of this project was to evaluate DART in the treatment of PIGD in people with PD compared to a Traditional DTT intervention. It was hypothesized that both groups would exhibit significant improvements in gait, and the improvements for the DART group would be non-inferior to Traditional DTT. METHODS: A single-blind randomized controlled trial was conducted with 47 PD participants with PIGD. Both groups completed 16 therapeutic sessions over 8 weeks; the DART platform delivered DTT via the Microsoft HoloLens2. Primary outcomes included clinical ratings and single- and dual-task gait biomechanical outcomes. RESULTS: Clinical measures of PD symptoms remained stable for DART and Traditional DTT groups. However, both groups exhibited a significant increase in gait velocity, cadence, and step length during single- and multiple dual-task conditions following the interventions. Improvements in gait velocity in the DART group were non-inferior to Traditional DTT under the majority of conditions. CONCLUSION: Non-inferior improvements in gait parameters across groups provides evidence of the DART platform being an effective digital therapeutic capable of improving PIGD. Effective digital delivery of DTT has the potential to increase use and accessibility to a promising, yet underutilized and difficult to administer, intervention for PIGD. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Dual-task Augmented Reality Treatment for Parkinson's Disease (DART) NCT04634331; posted November 18, 2020.

Outcome-based and Participation-based Wellness Incentives: Impacts on Program Participation and Achievement of Health Improvement Targets.

OBJECTIVE: This study examined whether worksite wellness program participation or achievement of health improvement targets differed according to four incentive types (participation-based, hybrid, outcome-based, and no incentive). METHODS: The study included individuals who completed biometric health screenings in both 2013 and 2014 and had elevated metrics in 2013 (baseline year). Multivariate logistic regression modeling tested for differences in odds of participation and achievement of health improvement targets between incentive groups; controlling for demographics, employer characteristics, incentive amounts, and other factors. RESULTS: No statistically significant differences between incentive groups occurred for odds of participation or achievement of health improvement target related to body mass index, blood pressure, or nonhigh-density lipoprotein cholesterol. CONCLUSIONS: Given the null findings of this study, employers cannot assume that outcome-based incentives will result in either increased program participation or greater achievement of health improvement targets than participation-based incentives.

Sources of mortality for a cynipid gall-wasp (Dryocosmus dubiosus (Hymenoptera: Cynipidae)): The importance of the Tannin/Fungus interaction.

Emergence success was determined for 1300 galls of the cynipid waspDryocosmus dubiosus. Galls were collected throughout a single host tree (a California coast live oakQuercus agrifolia). Each gall was reared individually in small gelatin capsules. For each gall data was recorded on 17 parameters characterizing hyperparasitism, fungal infestation, leaf tannin levels, inter- and intraspecific competition, and spatial position within the tree. Using contingency table analysis and logistic regression, we determined that the most significant factors influencing the success ofD. dubiosus galls are 1) fungal infestation and 2) chalcid hyperparasitism, both having negative effects. Of the factors investigated we found that leaf tannin level had the strongest influence on the degree of fungal infestation. Fungal infestation, in turn, is lowest in regions of high leaf tannins.

Design, development and validation of the RedBrick Health Assessment: a questionnaire-based study.

OBJECTIVES: Health risk assessment (HRA) questionnaires have become a popular tool to help quantify health issues within populations. Over the last decade HRAs have increasingly been delivered in the online environment. The objective of this study was to create and validate an HRA that is optimized for delivery via the Internet. DESIGN: After an iterative process of user testing and interface design the RedBrick Health Assessment (RBHA) was validated against known domain specific questionnaires with 464 working Americans, and with medical claims data from over 25,000 employees. SETTING: All consumer testing, data capture and analysis occurred at the offices of RedBrick Health Corporation, Minneapolis, USA and via a secure online portal. PARTICIPANTS: Individuals in full-time employment in the USA, who were between 18 and 65 years of age at the time inquiry. MAIN OUTCOME MEASURES: Correlation of the included RBHA domains with the output from known gold standard health question sets for each assessed health domain. RESULTS: The iterative development process employed in creating the RBHA produced a tool that had a high degree of user acceptability. The domains demonstrated good correlations with relevant gold standard questionnaire measures, good internal consistency, and acceptable sensitivity and specificity when compared to gold standard risk stratification and high-risk classification (specificity of domains ranged from 76-94%). A test-retest correlation co-efficient of 0.7, or greater, was achieved 8 weeks after initial completion. CONCLUSIONS: The RBHA is a new breed of HRA that has been specifically developed for capturing health status information in an online environment. At its heart is user centricity and this focus has enabled the creation of a tool that is not only highly engaging but also captures accurate and robust health status information.