The Relationship between Independent Transfer Skills and Upper Limb Kinetics in Wheelchair Users

Transfers are one of the most physically demanding wheelchair activities. The purpose of this study was to determine if using proper transfer skills as measured by the Transfer Assessment Instrument (TAI) is associated with reduced loading on the upper extremities. Twenty-three wheelchair users performed transfers to a level-height bench while a series of forces plates, load cells, and a motion capture system recorded the biomechanics of their natural transferring techniques. Their transfer skills were simultaneously evaluated by two study clinicians using the TAI. Logistic regression and multiple linear regression models were used to determine the relationships between TAI scores and the kinetic variables on both arms across all joints. The results showed that the TAI measured transfer skills were closely associated with the magnitude and timing of joint moments ( < .02, model R 2 values ranged from 0.27 to 0.79). Proper completion of the skills which targeted the trailing arm was associated with lower average resultant moments and rates of rise of resultant moments at the trailing shoulder and/or elbow. Some skills involving the leading side had the effect of increasing the magnitude or rate loading on the leading side. Knowledge of the kinetic outcomes associated with each skill may help users to achieve the best load-relieving effects for their upper extremities

BIOMARKERS OF UPPER-EXTREMITY SOFT TISSUE PATHOLOGY IN WHEELCHAIR USERS WITH SPINAL CORD INJURY

Wheelchair users with spinal cord injury (SCI) use upper-extremities to perform most activities, which may lead to upper-extremity pain. Wheelchair transfers and propulsion expose shoulder and wrist soft tissues to repetitive and forceful loads that can contribute to pathology. The proceeding investigations aim to further understand how wheelchair activities contribute to the development of soft tissue pathology using ultrasound and chemical biomarkers. The first three studies describe how wheelchair transfers effect ultrasound markers for pathology. A sample of wheelchair users with SCI was recruited and performed eighteen transfers within 10 minutes. Ultrasound images of the biceps and supraspinatus tendons were collected before and after transfers to assess tendon width, brightness, and composition. Clinical ultrasound markers were collected at the start of the protocol. Better transfer technique correlated with fewer ultrasound markers of shoulder pathology, and less transfer-related shoulder pain. Repeated-transfers acutely increased biceps tendon width and median nerve cross-sectional area; changes were influenced by greater bodyweight and specific transfer skills. A novel method of measuring glenohumeral joint (GHJ) inflammatory cytokines, using microdialysis, was developed for the final study. Six able-bodied veterans and one individual with SCI were recruited. A microdialysis catheter was inserted into the posterior GHJ space under ultrasound guidance. Participants performed a wheelchair propulsion and transfer protocol. Microdialysis samples and ultrasound were collected before and after the activity, and 30 and 60 minutes post-activity. IL-1RA and RANTES changed after the activity. Smaller RANTES increases were correlated with greater propulsive forces. Greater changes in IL-8 and IL-1RA were associated with darker tendons after activity, which indicates intratendinous edema. The findings suggest that inflammatory cytokine expression (local to the GHJ) contributes to rotator cuff tendinopathy. Furthermore, forceful upper-extremity activity may contribute to tendinopathy by amplifying cytokine expression. Biochemical markers are a valuable measure of inflammation that is reflective of soft tissue pathology and may provide investigators with a sensitive method to determine different wheelchair techniques that dampen the inflammatory response. Results from these studies indicate that wheelchair activities may cause an acute inflammatory response that affects tendon health, and that using better technique may help prevent the development of pathology

Evaluation of Eta model forecasts as a backup weather source for CTAS

Knowledge of present and future winds and temperature is important for air traffic operations in general, but is crucial for Decision Support Tools (DSTs) that rely heavily on accurately predicting trajectories of aircraft. One such tool is the CenterTRACON Automation System (CTAS) developed by NASA Ames Research Center. The Rapid Update Cycle (RUC) system is presently the principal source of weather information for CTAS.' RUC provides weather updates on an hourly basis on a nationwide grid with horizontal resolution of 40 km and vertical resolution of 25 mb in pressure. However, a recent study of RUC data availability showed that the NWS and NOAA servers are subject to frequent service interruptions. Over a 210 day period (4/19/0011/11/00), the availability of two NOAA and one NWS RUC server was monitored automatically. It was found that 60 days (29%) had periods of one hour or more where at least one server was out, with the longest outage lasting 13 hours on 9/21/00. In addition, there were 9 days (4%) for which all three servers were simultaneously unavailable, with the longest outage lasting 6 hours on 5/7/00. Moreover, even longer outages have been experienced with the RUC servers over the past several years. RUC forecasts are provided for up to 12 hours, but these are not currently used in CTAS as back up sources (except that the 1 or 2 hour forecasts are used for the current winds to compensate for transmission delays in obtaining the RUC data). Since RUC outages have been experienced for longer than 12 hours, it is therefore necessary to back RUC up with another weather source providing long-range forecasts. This paper examines the use of the Eta model forecasts as a back-up weather source for CTAS. A specific *This work was performed for the Federal Aviation Administration under Air Force Contract No. F19628-00-C-0002. tCopyright © 2001 by M.I.T. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. output of the Eta 32 km model, namely Grid 104, was selected for evaluation because its horizontal and vertical resolution, spatial extent and output parameters match most closely those of RUC. While RUC forecasts for a maximum of 12 hours into the future, Eta does so for up to 60 hours. In the event that a RUC outage would occur, Eta data could be substituted. If Eta data also became unavailable, the last issued forecasts could allow CTAS to continue to function properly for up to 60 hours. The approach used for evaluating the suitability of the Eta model and RUC forecasts was to compare them with the RUC analysis output or 0 hour forecast file, at the forecast time. Not surprisingly, it was found that the RUC model forecasts had lower wind magnitude errors out to 12 hours (the limit of the RUC forecasts) than the Eta model had. However, the wind magnitude error for the Eta model grew only from 9 ft/s at 12 hours (comparable with RUC) to 11 ft/s at 48 hours. We therefore conclude that RUC forecasts should be used for outages up to 12 hours and Eta model forecasts should be used for outages up to 60 hours

The design and implementation of the new center/TRACON automation system (CTAS) weather distribution system

The National Aeronautics and Space Administration (NASA), working with the Federal Aviation Administration (FAA), is developing a suite of decision support tools, called the Center/TRACON Automation System (CTAS). CTAS tools such as the Traffic Management Advisor (TMA) and Final Approach Spacing Tool (FAST) are designed to increase the efficiency of the air traffic flow into and through Terminal airspace. A core capability of CTAS is the Trajectory Synthesis (TS) software for accurately predicting an aircraft's trajectory. In order to compute these trajectories, TS needs an efficient access mechanism for obtaining the most up-to-date and accurate winds. The current CTAS weather access mechanism suffers from several major drawbacks.1 First, the mechanism can only handle a winds at a single resolution (presently 40-80 km). This prevents CTAS from taking advantage of high resolution wind from sources such as the Integrated Terminal Weather System (ITWS). Second, the present weather access mechanism is memory intensive and does not extend well to higher grid resolutions. This potentially limits CTAS in taking advantage of improvements in wind resolution from sources such as the Rapid Update Cycle (RUC). Third, the present method is processing intensive and limits the ability of CTAS to handle higher traffic loads. This potentially could impact the ability of new tools such as Direct-To and Multi-Center TMA (McTMA) to deal with increased traffic loads associated with adjacent Centers