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- d'Orgeville, Céline, et al.
(author)
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Preliminary results of the 2001-2002 Gemini sodium monitoring campaign at Cerro Tololo, Chile
- 2003
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In: Adaptive Optical System Technologies II. Edited by Wizinowich, Peter L.; Bonaccini, Domenico. Proceedings of the SPIE, Volume 4839, pp. 492-503 (2003).. ; 4839:Part 2, s. 492-503
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Conference paper (peer-reviewed)abstract
- In the near future several astronomical observatories in Chile areplanning to use sodium laser guide stars to increase the sky coverageprovided by their adaptive optics facilities. Knowledge of themesospheric sodium layer behavior is crucial to predict the performanceof future laser guide star adaptive optics systems. Whereas the sodiumlayer has been observed quite extensively at several locations, many ofthem in the Northern Hemisphere, very little measurements have been madein Chile. The Gemini Observatory therefore initiated a year-long sodiummonitoring campaign at the Cerro Tololo Inter-American Observatorylocated only a few kilometers away from the Gemini South telescope wherea conventional laser guide star facility will be offered to thecommunity in 2005, soon to be upgraded to a multi-conjugate adaptiveoptics system with five laser guide stars. This paper reports on thelaser-based sodium monitoring experimental set up and data reductiontechniques, and presents some preliminary results on the sodium columndensity and layer altitude variations observed from February 2001 toFebruary 2002. Implications for the Gemini South Adaptive Optics systemexpected performance are presented as well.
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2. |
- Lundblad, Lennart, et al.
(author)
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Thoracic gas volume measurements in paralyzed mice
- 2004
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In: Annals of Biomedical Engineering. - 1573-9686. ; 32:10, s. 1420-1427
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Journal article (peer-reviewed)abstract
- We have previously measured thoracic gas volume (V-TG) in spontaneously breathing mice using a whole body plethysmograph and have now extended our technique to allow for V-TG measurements during paralysis. BALB/c mice were anesthetized and placed in a body-box and ventilated via a tracheostomy cannula through the box wall. Box pressure (P-b) and tracheal pressure (P-ao) were measured during spontaneous breathing, and again after paralysis while mechanically compressing the chest. V-TG was much larger after paralysis (0.49+/-0.06 ml, positive end-expiratory pressure=2 cmH(2)O) when compared with spontaneous breathing (0.31+/-0.01 ml). External chest compression produced looping in the plots of P-b versus P-ao that was attributable to gradual changes in P-b upon release of the mechanical chest compression and had the character of thermal transients. Under the assumption that the rate of heating of the air in the chamber was proportional to the pressure applied to the animal's chest, and that any increase in air temperature was dissipated by heat absorption by the chamber walls, we developed an algorithm that corrected for the thermal events. This yielded similar results for V-TG (0.30+/-0.02 ml) as obtained during spontaneous efforts. Our method may prove particularly useful when paralysis is required for the precise measurement of lung mechanics.
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