Improved reversible coulometer cell

Cell operates either as timer or current-time integrating device in any physical orientation with better than 2 percent accuracy over temperature range of 283 K to 398 K, with input current range from few microamperes to approximately 1000 microamperes over time period of 1 sec to several hours

Swimming Performance Post Blood Flow Restriction Training in Collegiate Swimmers

PURPOSE: To determine if blood flow restriction (BFR) training improved performance and physiological factors in collegiate swimmers. METHODS: Participants (n=10) separated into 2 groups (control [CON] & experimental [OCC]), completed 9 supervised trainings within 3 weeks. Pre- and post-testing included: VO2max, Wingate, swim time trials (TT), strength, and DEXA. Training was identical except OCC underwent bilateral thigh BFR [blood pressure (BP) cuffs inflated 70-90% of systolic BP]. Training: treadmill walking 20 minutes (5x3-minutes at 3 mph, 5% grade, 1-minute rest), followed by bodyweight strength training (squats, lunges & step-ups). Pain levels (scale: 1-10) were taken after the second set of lunges, cuff inflated (PainA), and after all lunges, cuff deflated (PainB). Paired t-tests determined significant change within groups, independent t-tests determined significance between groups, ReANOVA determined significance of pain levels. RESULTS: Both groups increased 1 RM leg press CON: 18.0 ± 8.155 (kg) (p=0.008) and OCC: 15.200 ± 5.805 (p=0.004); 1 RM chest press (kg) increased significantly in OCC (p=0.031). Mean peak power (W/kg) increased 1.530 ± 2.389 (p=0.225) CON and 3.772 ± 3.088 OCC (p=0.052). Pain levels were significantly different between days (p=0.012), and between PainA vs PainB (p=0.008). No significant change in swimming TT, VO2max, total work, fatigue index, or body fat occurred. CONCLUSION: This BFR training program did not improve swimming performance but indicated adaptation to pain may occur

GRB990123: The Case for Saturated Comptonization

The recent simultaneous detection of optical, X-ray and gamma-ray photons from GRB990123 during the burst provides the first broadband multi-wavelength characterization of the burst spectrum and evolution. Here we show that a direct correlation exists between the time-varying gamma-ray spectral shape and the prompt optical emission. This combined with the unique signatures of the time-resolved spectra of GRB990123 convincingly supports earlier predictions of the saturated Comptonization model. Contrary to other suggestions, we find that the entire continuum from optical to gamma-rays can be generated from a single source of leptons (electrons and pairs). The optical flux only appears to lag the gamma-ray flux due to the high initial Thomson depth of the plasma. Once the plasma has completely thinned out, the late time afterglow behavior of our model is the same as in standard models based on the Blandford-McKee (1976) solution.Comment: 10 pages, including 3 figures and 1 table, submitted to The Astrophysical Journal Letter

Planetary entry parachute program

Material strength, shock loading, and stress analyses for planetary entry parachute desig

Jamming Model for the Extremal Optimization Heuristic

Extremal Optimization, a recently introduced meta-heuristic for hard optimization problems, is analyzed on a simple model of jamming. The model is motivated first by the problem of finding lowest energy configurations for a disordered spin system on a fixed-valence graph. The numerical results for the spin system exhibit the same phenomena found in all earlier studies of extremal optimization, and our analytical results for the model reproduce many of these features.Comment: 9 pages, RevTex4, 7 ps-figures included, as to appear in J. Phys. A, related papers available at http://www.physics.emory.edu/faculty/boettcher