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A- and b-type rotational transitions of N2-OCS between 6 and 18 GHz have been recorded using a pulsed, supersonic nozzle, Fourier-transform microwave spectrometer. The rotational spectrum is indicative of a planar, T-shaped complex, with the nitrogen molecular axis oriented toward the carbon of OCS. Symmetry effects in the nuclear quadrupole hyperfine structure imply that the nitrogen nuclei are effectively equivalent due to rotation of the nitrogen molecule. The resulting symmetric and antisymmetric combined nuclear spin and tunneling states are associated with slightly different rotational and hyperfine parameters. First-order quadrupole and spin-rotation interactions are used to fit the hyperfine structure, and the hyperfine dependence on rotational state is investigated. An instance of accidental near-degeneracy has allowed determination of the χab off-diagonal quadrupole coupling constant for the symmetric state. Deduced structural parameters have been compared with a model based on distributed multipole, dispersion, and hard sphere interactions. The quadrupole coupling constants of the two tunneling symmetry states have been used to model the angular tunneling potential, giving a barrier to rotation of 40.44 cm-1 and a tunneling frequency of 2450.0 GHz. © 1996 Academic Press, Inc.

Context.—Preemptive analgesia can decrease the sensitization of the central nervous system that would ordinarily amplify subsequent nociceptive input, but a clear demonstration of its clinical efficacy is necessary for it to become a routine component of acute pain therapy.Objective.—To determine the impact of preemptive epidural analgesia on postoperative pain and other clinically important outcome variables after radical retropubic prostatectomy.Design and Setting.—A block randomized double-blind clinical trial lasting 20 months at a single academic medical center.Patients.—A total of 100 generally healthy and neurologically intact patients scheduled for radical retropubic prostatectomy for the treatment of prostate cancer in whom an epidural catheter for treating postoperative pain was to be placed prior to the induction of general anesthesia.Interventions.—Epidural bupivacaine, epidural fentanyl, or no epidural drug was administered prior to induction of anesthesia and throughout the entire operation, followed by aggressive postoperative epidural analgesia for all patients.Main Outcome Measures.—Daily pain scores during hospitalization and pain scores obtained 3.5, 5.5, and 9.5 weeks after hospital discharge.Results.—The patients who received epidural fentanyl or bupivacaine prior to surgical incision (preemptive analgesia) experienced 33% less pain while hospitalized (P=.007). Pain scores in those receiving preemptive analgesia were significantly lower at 9.5 weeks (P=.02), but were not significantly different at 3.5 or 5.5 weeks. At 9.5 weeks, 32 (86%) of 37 patients receiving preemptive analgesia were pain-free compared with 9 (47%) of 19 control patients (P=.004). Patients receiving preemptive analgesia were more active 3.5 weeks after surgery (P=.01), but not at 5.5 or 9.5 weeks.Conclusions.—Even in the presence of aggressive postoperative pain management, preemptive epidural analgesia significantly decreases postoperative pain during hospitalization and long after discharge, and is associated with increased activity levels after discharge.