Calibration method using a single retarder to simultaneously measure polarization and fully characterize a polarimeter over a broad range of wavelengths.

A method has been developed to improve the accuracy with which the polarization state of light can be characterized by the rotating quarter-wave plate technique. Through detailed analysis, verified by experiment, we determine the positions of the optic axes of the retarder and linear polarizer, and the wave plate retardance, to better than 1° for typical signal-to-noise ratios. Accurate determination of the Stokes parameters can be achieved using a single wave plate for a wide range of optical wavelengths using this technique to determine the precise retardance at each of the wavelengths of interest.

Medical errors in orthopaedics. Results of an AAOS member survey.

BACKGROUND: There has been widespread interest in medical errors since the publication of To Err Is Human: Building a Safer Health System by the Institute of Medicine in 2000. The Patient Safety Committee of the American Academy of Orthopaedic Surgeons has compiled the results of a member survey to identify trends in orthopaedic errors that would help to direct quality assurance efforts. METHODS: Surveys were sent to 5540 Academy fellows, and 917 were returned (a response rate of 16.6%), with 53% (483) reporting an observed medical error in the previous six months. RESULTS: A general classification of errors showed equipment (29%) and communication (24.7%) errors with the highest frequency. Medication errors (9.7%) and wrong-site surgery (5.6%) represented serious potential patient harm. Two deaths were reported, and both involved narcotic administration errors. By location, 78% of errors occurred in the hospital (54% in the surgery suite and 10% in the patient room or floor). The reporting orthopaedic surgeon was involved in 60% of the errors; a nurse, in 37%; another orthopaedic surgeon, in 19%; other physicians, in 16%; and house staff, in 13%. Wrong-site surgeries involved the wrong side (59%); another wrong site, e.g., the wrong digit on the correct side (23%); the wrong procedure (14%); or the wrong patient (5% of the time). The most frequent anatomic locations were the knee and the fingers and/or hand (35% for each), the foot and/or ankle (15%), followed by the distal end of the femur (10%) and the spine (5%). CONCLUSIONS: Medical errors continue to occur and therefore represent a threat to patient safety. Quality assurance efforts and more refined research can be addressed toward areas with higher error occurrence (equipment and communication) and high risk (medication and wrong-site surgery).