Enhancements to the JET poloidally scanning vacuum ultraviolet∕visible spectrometers

Enhancements to the JET poloidally scanning spectrometers are presented, which will aid the exploitation of the recently installed ITER-like wall in JET. They include the installation of visible filter∕photomultiplier tube assemblies and spectrometers and the replacement of large rotating mirrors in the JET vacuum with small oscillating mirrors outside. The upgrade has resulted in a more robust and reliable diagnostic than before, which is described. Drifts in the mirror angle reconstructed from quadrature encoder signals are found, a reference signal being required. The use of the small scanning mirrors necessitated the inclusion of focusing mirrors to maintain throughput into the vacuum ultraviolet spectrometers. The mirror design has taken account of the extreme sensitivity of the focusing to the grazing angle of incidence, an aspect of importance in the design of grazing incidence focusing components on future machines, such as ITER. The visible system has been absolutely calibrated using an in-vessel light source.

Randomized double-blind study of the clinical duration and efficacy of Nesacaine-MPF 2% and 3% in peribulbar anesthesia

PURPOSE

To compare 2 commercially available concentrations of Nesacaine-MPF (2-chloroprocaine) to determine the time to onset of adequate motor blockade, the quality of surgical anesthesia, and the duration of motor blockade in the extraocular muscles after peribulbar anesthesia for cataract surgery.

SETTING

Tampa Eye and Specialty Surgery Center, Tampa, Florida, USA.

METHODS

This double-blind, randomized, single-center study comprised 40 patients scheduled to receive peribulbar anesthesia before cataract surgery. Patients were given 5 mL of Nesacaine-MPF 2% or 3% before surgery. Beginning at the end of the injection, assessments of ocular and eyelid movement were made every 2 minutes until adequate motor blockade was achieved or 25 minutes elapsed. Ocular assessments were made immediately after completion of surgery, 60 minutes after the end of the initial injection, and at 15 minute intervals thereafter until full recovery. Assessments of the quality of anesthesia achieved by the patient during surgery were made by the surgeon.

RESULTS

The 3% solution provided significantly faster onset of surgical anesthesia than the 2% solution (mean 3.9 minutes +/- 2.2 [SD] versus 6.0 +/- 3.6 minutes) (P = .02) but also required more time for recovery from anesthesia (98.9 +/- 18.7 minutes versus 84.8 +/- 20.6 minutes) (P = .02). All patients had adequate surgical anesthesia. Duration of ocular motor function was brief enough so that all patients could be sent home without an eye patch. Both concentrations were safe for use in this procedure.

CONCLUSION

Both Nesacaine-MPF 2% and 3% produced safe and effective peribulbar anesthesia in all patients; however, the 3% solution provided better duration of clinical anesthesia.

The Magnitude of Bias in the Measurement of PM25 Arising from Volatilization of Particulate Nitrate from Teflon Filters

Because the Federal Reference Method for PM25 specifies the collection of ambient particles on Teflon filters, we have examined the loss of a known volatile species, particulate nitrate, during sampling. Data are presented from two studies in southern California for which parallel samples were collected by different methods. Differences in collected nitrate are modeled using an evaporation model based on the work of Zhang and McMurry. The average nitrate obtained from sampling with Teflon filters was 28% lower on average than that measured by denuded nylon filters. In contrast, cascade impactor samples were within 5% of the denuded nylon filter on average. A simple model is presented that accounts for the particulate nitrate loss from Teflon filters either by scavenging nitric acid and ammonia in the sampler inlet or by heating the filter substrate during sampling. The observed magnitude of loss is explained by any of the following situations: (1) 100% nitric acid and ammonia vapor loss in the inlet, (2) 5 °C heating of the filter substrate above ambient temperature during sampling, or (3) a combination of these factors, such as 50% vapor loss in the inlet and 3 °C heating of the filter.