RESUMO
We demonstrate controllable excitation of the center-of-mass longitudinal motion of a thermal antiproton plasma using a swept-frequency autoresonant drive. When the plasma is cold, dense, and highly collective in nature, we observe that the entire system behaves as a single-particle nonlinear oscillator, as predicted by a recent theory. In contrast, only a fraction of the antiprotons in a warm plasma can be similarly excited. Antihydrogen was produced and trapped by using this technique to drive antiprotons into a positron plasma, thereby initiating atomic recombination.
RESUMO
OBJECTIVE: To determine the effect of conversion to soft-copy interpretation on the number of images and imaging time. MATERIALS AND METHODS: Before and 1 year after conversion to soft-copy interpretation, 20 consecutive normal abdominal, renal, and cranial sonograms were performed by each of three technologists (360 sonograms total). The number of images and imaging time per sonogram were recorded. For each technologist and each examination type, the differences between number of images and the imaging times before and after conversion were compared. Multivariate repeated measures analysis of variance was used to analyze the data. RESULTS: After conversion to soft-copy, the number of images significantly increased for all imaging types (P = 0.004), and the imaging time significantly decreased (P < 0.001). After conversion, there were 213 more images. The average number of images increased 1.0 per abdominal sonogram, 0.5 per renal sonogram, and 2.0 per cranial sonogram. The additional storage requirement for the 213 images was 64 MB; total long-term storage media cost increased $1.06. On average, there was a 19% decrease in imaging time, with abdominal imaging time decreasing 2 min and 18 s, renal 1 min and 46 s, and cranial 40 s. This would potentially allow time for two additional sonograms to be performed per day and would generate up to $112,000 additional revenue per year. CONCLUSION: Following soft-copy conversion, there was a significant increase in the number of images acquired per examination, with an increased storage requirement but a negligible increase in storage cost. Technologist efficiency significantly improved.
