The Greenland Telescope project has recently participated in an experiment to image the supermassive black hole shadow at the center of M87 using Very Long Baseline Interferometry technique in April ...of 2018. The antenna consists of the 12-m ALMA North American prototype antenna that was modified to support two auxiliary side containers and to withstand an extremely cold environment. The telescope is currently at Thule Air Base in Greenland with the long-term goal to move the telescope over the Greenland ice sheet to Summit Station. The GLT currently has a single cryostat which houses three dual polarization receivers that cover 84-96 GHz, 213-243 GHz and 271-377 GHz bands. A hydrogen maser frequency source in conjunction with high frequency synthesizers are used to generate the local oscillator references for the receivers. The intermediate frequency outputs of each receiver cover 4-8 GHz and are heterodyned to baseband for digitization within a set of ROACH-2 units then formatted for recording onto Mark-6 data recorders. A separate set of ROACH-2 units operating in parallel provides the function of auto-correlation for real-time spectral analysis. Due to the stringent instrumental stability requirements for interferometry a diagnostic test system was incorporated into the design. Tying all of the above equipment together is the fiber optic system designed to operate in a low temperature environment and scalable to accommodate a larger distance between the control module and telescope for Summit Station. A report on the progress of the above electronics instrumentation system will be provided.
Laparoscopy under total intravenous anesthesia (TIVA) with spontaneous respiration is a commonly encountered procedure in ambulatory gynecologic surgery. The purpose of this study was to evaluate the ...efficacy of TIVA using propofol and ketamine, compared with endotracheal inhalational general anesthesia (EIGA) for ambulatory gynecologic laparoscopy. Fifty-eight female patients, aged 17-48 years, were randomly allocated into two groups. Group 1 (TIVA) (n = 28) received propofol at the induction of anesthesia followed by propofol infusion for maintenance. Intravenous ketamine 0.5 mg/kg was administered before operation for anesthetic effect. Natural airway and spontaneous breathing were then maintained in patients. Group 2 (n = 30) received EIGA with isoflurane under controlled ventilation. We found that the two groups demonstrated similar trend characters of pH and PaCO2 during operation and in recovery room. The incidence of postoperative vomiting was higher in group 2 than in group 1 (30% vs. 7%; p < 0.05). The incidence of intraoperative arrhythmia was higher in group 2 than in group 1 (40% vs. 3%; p < 0.001). Furthermore, the incidence of sore throat was higher in group 2 than in group 1 (47% vs. 7%; p < 0.001). We conclude that TIVA with spontaneous respiration is suitable for ambulatory gynecologic laparoscopy.
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