Langmuir flow effects in the laser gyro

Langmuir flow effects have been investigated in the laser gyro by measuring the integral of the beat frequency while tuning the frequency of oscillation. The results are in agreement with the traveling-wave Lamb model. The presence of the dc discharge tube walls gives rise to gas circulation in the laser gyro cavity. If the oppositely directed traveling waves see a net gas flow the gyro exhibits a null shift which depends on the magnitude and direction of the discharge current unbalance causing the net gas flow. The null shift is shown to be due to the mode pulling and pushing associated with the anomalous dispersion exhibited by the gain atoms.     

Efficient Speaker Recognition Using Approximated Cross Entropy (ACE)

Techniques for efficient speaker recognition are presented. These techniques are based on approximating Gaussian mixture modeling (GMM) likelihood scoring using approximated cross entropy (ACE). Gaussian mixture modeling is used for representing both training and test sessions and is shown to perform speaker recognition and retrieval extremely efficiently without any notable degradation in accuracy compared to classic GMM-based recognition. In addition, a GMM compression algorithm is presented. This algorithm decreases considerably the storage needed for speaker retrieval.     

Electrostatic Potential Generated by Rockets on Vehicles in Space

Investigators have reported the existence of electric current in the exhaust plumes of rocket engines and have speculated that this current could generate a sufficiently high electrostatic potential on vehicles in space to interfere with or damage electronic subsystems or instrumentation. This paper identifies the source of the observed current, calculates its magnitude as a function of the engine parameters, and demonstrates that the rocket plume itself can discharge a vehicle in space and prevent buildup of dangerous potentials.     

Outpatient ACL reconstruction using intraoperative local analgesia and oral postoperative pain medication

Thirty-five consecutive anterior cruciate ligament (ACL) reconstructions were performed in an ambulatory surgical unit using a bone-patellar tendon-bone autograft. Patients were evaluated postoperatively to determine the amount of pain medication used, the readmission rate, postoperative complications, and cost. Outpatient ACL reconstruction led to a savings of $4700 compared with the cost of performing the same procedure in a hospital operating room with an overnight admission. This study demonstrates that outpatient ACL reconstruction, using local analgesia intraoperatively and oral narcotic pain medication postoperatively, is a safe and cost-effective procedure with minimal to no morbidity.     

A methodology for deep sub-0.25 μm CMOS technology prediction

We present a novel methodology for characterization of sub-quartermicron CMOS technologies. It involves process calibration, device calibration employing two-dimensional device simulation and automated Technology Computer Aided Design (TCAD) optimization and, finally, transient mixed-mode device/circuit simulation. The proposed methodology was tested on 0.25 μm technology and applied to 0.13 μm technology in order to estimate ring oscillator speed. The simulation results show an excellent agreement with available experimental data