Wearable Knee Health Rehabilitation Assessment using Acoustical Emissions

Each year, approximately 200,000 Americans endure anterior cruciate ligament (ACL) tears, and 100,000 reconstructive procedures are conducted to repair the injured knees (1). The injury itself, and the long rehabilitation process that follows, can majorly disrupt the quality of life for these Americans through missed workdays, reduction of overall physical activity, and increased risk of re-injury in future activities. Wearable technologies for quantifying the state of rehabilitation, and providing feedback to the user regarding which activities or intensities of activities are safe to perform at any given time, could potentially help accelerate the rehabilitation process as well as reduce the risk of re-injury. Our lab has developed a novel, wearable sensing system based on miniature piezoelectric contact microphones for measuring the acoustical emissions from the knee during movements such as unloaded flexion / extension, sit-to-stand, and walking activities. The system consists of two Knowles BU-23173 contact microphones (Knowles, Itasca, IL) positioned on the medial and lateral sides of the patella, connected to custom, analog pre-amplifier circuits and a microcontroller for digitization and data storage on a secure digital (SD) card. In addition to the acoustical sensing, the system includes two integrated inertial measurement sensors including accelerometer and gyroscope modalities to enable joint angle calculations; these sensors, with digital outputs, are connected directly to the same microcontroller via serial peripheral interface (SPI). The system provides low noise, accurate joint acoustical emission and angle measurements in a wearable form factor, and has several hours of battery life. We have also taken measurements from healthy subjects, and athletes following acute ACL tear, to determine initial features from these acoustical emissions that are associated with injured versus healthy joints. We have found that the main acoustic clicks during particular motions occurred at consistent joint angles for healthy subjects based on intraclass correlation coefficient analysis (ICC(1,1) = 0.94 and ICC(1,k) = 0.99) (2). For one subject with an ACL tear, we found that the consistency of the joint acoustical emissions was lower for the injured knee as compared to the healthy knee in the recording immediately following the injury (\u3c 7 days), and improved following six months of rehabilitation. We envision using the wearable system we have recently completed to conduct further experiments with subjects following acute ACL tears, and tracking the progress of the rehabilitation while simultaneously measuring acoustical emissions in the context of particular movements. This data will then serve as a foundation for creating subject-specific algorithms for assessing rehabilitation and providing feedback to the users

Low computational complexity mode division multiplexed OFDM transmission over 130 km of few mode fiber

We demonstrate 337.5-Gb/s MDM-8QAM-OFDM transmission over 130 km of FMF. This confirms that OFDM can significantly reduce the required DSP complexity to compensate for differential mode delay, a key step towards real-time MDM transmission

Risk factors for mortality-morbidity after emergency-urgent colorectal surgery

Background: The aim of this study was to assess the risk factors associated with mortality and morbidity following emergency or urgent colorectal surgery. Materials and methods: All data regarding the 462 patients who underwent emergency colonic resection in our institution between November 2002 and December 2007 were prospectively entered into a computerized database. Results: The median age of patients was 73 (range 17-98)years. The most common indications for surgery were: 171 adenocarcinomas (37%), 129 complicated diverticulitis (28%), and 35 colonic ischemia (7.5%). Overall mortality and morbidity rates were 14% and 36%, respectively. In multivariate analysis, the only parameter significantly associated with postoperative mortality was blood loss >500cm3 (odds ratio (OR) = 3.33, 95% confidence interval (CI) 1.63-6.82, p = 0.001). There were three parameters which correlated with postoperative morbidity: ASA score ≥3 (OR = 2.9, 95% CI 1.9-4.5, p < 0.001), colonic ischemia (OR = 3.4, 95% CI 1.4-7.7, p = 0.006), and stoma creation (OR = 2.2, 95% CI 1.4-3.4, p = 0.0003). Conclusions: The main risk factors for postoperative morbidity and mortality following emergency colorectal surgery are related to: (1) patients' ASA score, (2) colonic ischemia, and (3) perioperative bleeding. These variables should be considered in the elaboration of future scoring systems to predict outcome of emergency colorectal surger

Modulation of the Blood-Brain Barrier by Sigma-1R Activation

Sigma non-opioid intracellular receptor 1 (Sigma-1R) is an intracellular chaperone protein residing on the endoplasmic reticulum at the mitochondrial-associated membrane (MAM) region. Sigma-1R is abundant in the brain and is involved in several physiological processes as well as in various disease states. The role of Sigma-1R at the blood-brain barrier (BBB) is incompletely characterized. In this study, the effect of Sigma-1R activation was investigated in vitro on rat brain microvascular endothelial cells (RBMVEC), an important component of the blood-brain barrier (BBB), and in vivo on BBB permeability in rats. The Sigma-1R agonist PRE-084 produced a dose-dependent increase in mitochondrial calcium, and mitochondrial and cytosolic reactive oxygen species (ROS) in RBMVEC. PRE-084 decreased the electrical resistance of the RBMVEC monolayer, measured with the electric cell-substrate impedance sensing (ECIS) method, indicating barrier disruption. These effects were reduced by pretreatment with Sigma-1R antagonists, BD 1047 and NE 100. In vivo assessment of BBB permeability in rats indicates that PRE-084 produced a dose-dependent increase in brain extravasation of Evans Blue and sodium fluorescein brain; the effect was reduced by the Sigma-1R antagonists. Immunocytochemistry studies indicate that PRE-084 produced a disruption of tight and adherens junctions and actin cytoskeleton. The brain microcirculation was directly visualized in vivo in the prefrontal cortex of awake rats with a miniature integrated fluorescence microscope (aka, miniscope; Doric Lenses Inc.). Miniscope studies indicate that PRE-084 increased sodium fluorescein extravasation in vivo. Taken together, these results indicate that Sigma-1R activation promoted oxidative stress and increased BBB permeability

Comparison of a thigh worn accelerometer algorithm with diary estimates of time in bed and time asleep: the 1970 British Cohort Study

Background: Thigh-worn accelerometers have established reliability and validity for measurement of free-living physical activity-related behaviors. However, comparisons of methods for measuring sleep and time in bed using the thigh-worn accelerometer are rare. The authors compared the thigh-worn accelerometer algorithm that estimates time in bed with the output of a sleep diary (time in bed and time asleep). Methods: Participants (N = 5,498), from the 1970 British Cohort Study, wore an activPAL device on their thigh continuously for 7 days and completed a sleep diary. Bland–Altman plots and Pearson correlation coefficients were used to examine associations between the algorithm derived and diary time in bed and asleep. Results: The algorithm estimated acceptable levels of agreement with time in bed when compared with diary time in bed (mean bias of −11.4 min; limits of agreement −264.6 to 241.8). The algorithm-derived time in bed overestimated diary sleep time (mean bias of 55.2 min; limits of agreement −204.5 to 314.8 min). Algorithm and sleep diary are reasonably correlated (ρ = .48, 95% confidence interval [.45, .52] for women and ρ = .51, 95% confidence interval [.47, .55] for men) and provide broadly comparable estimates of time in bed but not for sleep time. Conclusions: The algorithm showed acceptable estimates of time in bed compared with diary at the group level. However, about half of the participants were outside of the ±30 min difference of a clinically relevant limit at an individual level