The Gamma-Ray Optical Counterpart Search Experiment (GROCSE) presents new experimental upper limits on the optical flux from gamma-ray bursts (GRBs). Our experiment consisted of a fully-automated very wide-field opto-electronic detection system that imaged locations of GRBs within a few seconds of receiving trigger signals provided by BATSE's real-time burst coordinate distribution network (BACODINE). The experiment acquired 3800 observing hours, recording 22 gamma-ray burst triggers within ∼30 s of the start of the burst event. Some of these bursts were imaged while gamma-ray radiation was being detected by BATSE. We identified no optical counterparts associated with gamma-ray bursts amongst these events at the m V ∼ 7.0 to 8.5 sensitivity level. We find the ratio of the upper limit to the V-band optical flux, F ν , to the gamma-ray fluence, Φ γ , from these data to be 2 × 10 −18 < F ν /Φ γ < 2 × 10 −16 .
During balance rehabilitation, physical therapists typically provide verbal instruction and/or physically reposition a patient to demonstrate proper postural position and movements. We have developed a wireless device that enables an expert (such as a physical therapist) to map his/her movements to a trainee in a hands-free fashion. The trainee is subsequently able to mimic the motion of the expert by interpreting positional cues presented via vibrotactile feedback to the relevant body segments. This device will potentially enable a therapist to aid multiple patients simultaneously and/or remotely, or enable a trainee (such as an athlete or student) to replicate expert movements. The device comprises an Expert Module (EM) and Trainee Module (TM). Both the EM and TM are composed of six degree-of-freedom inertial measurement units, microcontrollers, and batteries. The TM also has an array of vibrating actuators that provides the user with vibrotactile biofeedback. The expert dons the EM, and his/her relevant body position is computed by an algorithm based on an extended Kalman filter that provides asymptotic state estimation. The captured body position information is transmitted wirelessly to the trainee, and directional instructions regarding the desired motion/position are displayed via vibrotactile feedback. The trainee is instructed to move in the direction of the vibration sensation until the vibration is eliminated. While prior work has demonstrated the use of vibrotactile stimulation for improved motor learning, this portable and wireless device is suitable for use outside of a laboratory environment. Five healthy young blindfolded subjects were instructed to mimic recorded expert anterior-posterior trunk tilt motion using the aforementioned device in a series of proof-of-concept studies designed to investigate the effects of changing the feedback activation threshold and varying the nature of the feedback. To characterize the efficacy of the system, we performed a cross correlation of expert and trainee trunk tilt angle while varying the threshold angle difference at which vibrotactile feedback was applied. Preliminary results showed that subjects performed best at 0.5 and 0.75 degree thresholds among those tested (0.5, 0.75, 1.0, 1.25, 1.5). The normalized mean cross correlations for the 0.5 and 0.75 threshold conditions were 0.96 and 0.97 respectively, while the mean differences between expert and trainee trunk tilt angles were 1.1 and 1.2 degrees respectively. Further studies at 0.5 and 0.75 threshold conditions confirmed that proportional plus derivative feedback of the angle difference resulted in superior performance compared to proportional or derivative feedback alone. Repetition of the task was not significant suggesting that trainees could immediately use the device to accurately replicate expert anterior-posterior trunk tilt movements.
Visual, vibrotactile, and auditory cues have proven successful in numerous applications to supplement or in some cases completely replace missing sensory information. Sensory substitution using vibrotactile stimulation has been effective in improving postural stability during stationary tasks and tasks involving perturbed stance. The challenge increases, however, when designing a wearable device that provides meaningful information during a dynamic task such as walking. Techniques that directly apply the feedback strategies effective in stance (trunk tilt) to walking have largely proven ineffective (excluding heel-to-toe walking, which is essentially a series of standing balance tasks). We have demonstrated a device for correcting vestibulopathic gait using a novel feedback methodology that was co-developed with physical therapists specializing in balance rehabilitation. The device supplies vibrotactile cues based on factors during walking that are considered important by physical therapists, including gait velocity, stride length, and gaze. The device consists of three independent units, each consisting of an inertial measurement unit (IMU), vibrotactile display, and microprocessor. Head tilt (which approximates eye gaze), trunk tilt, stride length, and velocity are estimated by the IMUs and displayed to the patient in the form of vibrotactile cues on the head, trunk, and tibia, respectively. Algorithms were developed to estimate stride length and gait velocity in real time from measured heel-strike and toe-off events. Feedback of the head pitch angle is provided continuously to the subject, while gait velocity and stride length feedback are provided during heel strike events only. Preliminary results demonstrate that healthy subjects can interpret this feedback to correct their head pitch and adjust their stride length and gait velocity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.