These results support the use of single preoperative dose of antibiotics in lumbar disc surgery. This is relevant as many lumbar diskectomy patients are candidates for early hospital discharge. At our institution, no increased risk of infection occurred for the single dose group.
SIM PlanetQuest will exploit the classical measuring tool of astrometry (interferometry) with unprecedented precision to make dramatic advances in many areas of astronomy and astrophysics." (1) In order to achieve the required pointing precision of SIM, a gimbaled Siderostat (SID) pointing mechanism with coarse and fine stage actuators is being employed. In order to better understand the coarse pointing accuracy, a team of engineers set out to design, build, and test a linear ballscrew actuator that can perform submicron incremental steps for 10 years of continuous operation. Point tracking and low disturbance requirements lead the team to implement a ballscrew actuator with a direct drive DC motor and a piezo brake. By using an off the shelf motor, Hall effect sensor, ballscrew, and glass scale encoder, repeatable 20 nm incremental steps (actuator resolution) over a 120mm range was achieved. The results exceed expectations by a factor of 50 times and prove linear nanometer positioning requires no gears, levers, or hydraulic converters.12
In this paper we describe a hierarchid robot controller designed and built at NASA's Johnson Space Center. The mbot used is a six dep-of-freedom hydraulic manipulator equipped with joint position sensors and a wrist forcebrque sensor. The objective of the project is to emulate the performance chcteristics of the Space Station's Special Purpose Dexterous Manipulator (SPDM), which will perform various telerobotic extemal maintenance tasks. Some feaaues implemented in the controller include a resolved position control algorithm, force/moment accommodation, and gravity compensation. This multiple-processor control system is divided, by processor, into a servo controller, a forcehnoment data filter, a Cartesian-space controller, a host/Mic conmller and a network communication controller. This paper describes the functions of each individual processor and the design of their inter-processor communication.
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