Response to the letter of M. Brugnoli
1. In the Aquatrainer, the Xowmeter is positioned at the end of a long corrugated hose, and therefore, the temperature of the exhaled gases before being measured is assumed to be the same as that of the surrounding environment (i.e., ambient temperature). This requires a signiWcant expiratory BTPS correction. The user is thus requested to enter in the appropriate input Weld (i.e., temperature @ Xowmeter) the measured ambient temperature.
Is the new AquaTrainer® snorkel valid for VO2 assessment in swimming?
The Cosmed AquaTrainer® snorkel, in connection with the K4b2 analyzer, is the most recent instrument used for real time gas analysis during swimming. This study aimed to test if a new AquaTrainer® snorkel with 2 (SV2) or 4 (SV4) valves is comparable to a standard face mask (Mask) being valid for real time gas analysis under controlled laboratory and swimming pool conditions. 9 swimmers performed 2 swimming and 3 cycling tests at 3 different workloads on separate days. Tests were performed in random order, at constant exercise load with direct turbine temperature measurements, breathing with Mask, SV4 and SV2 while cycling, and with SV2 and SV4 while swimming. A high agreement was obtained using Passing - Bablok regression analysis in oxygen consumption, carbon dioxide production, tidal volumes, pulmonary ventilation, expiratory fraction of oxygen and carbon dioxide, and heart rate comparing different conditions in swimming and cycling. Proportional and fixed differences were always rejected (95% CI always contained the value 1 for the slope and the 0 for the intercept). In conclusion, the new SV2 AquaTrainer® snorkel, can be considered a valid device for gas analysis, being comparable to the Mask and the SV4 in cycling, and to the SV4 in swimming.
The Unusual Variability of the Large Magellanic Cloud Planetary Nebula RPJ 053059–683542
We present images and light curves of the bipolar planetary nebula RPJ 053059-683542 that was discovered in the Reid-Parker AAO UKST Hα survey of the Large Magellanic Cloud. The emission from this object appears entirely nebular, with the central star apparently obscured by a central band of absorption that bisects the nebula. The light curves, which were derived from images from the SuperMACHO project at CTIO, showed significant, spatially resolved variability over the period 2002 January through 2005 December. Remarkably, the emission from the two bright lobes of the nebula vary either independently or similarly but with a phase lag of at least 1 yr. The optical spectra show a low level of nebular excitation, and only modest N enrichment. Infrared photometry from the 2MASS and SAGE surveys indicates the presence of a significant quantity of dust. The available data imply that the central star has a close binary companion and that the system has undergone some kind of outburst event that caused the nebular emission to first brighten and then fade. Further monitoring, high-resolution imaging, and detailed IR polarimetry and spectroscopy would uncover the nature of this nebula and the unseen ionizing source.