Congruent validity and reliability of two metabolic systems to measure resting metabolic rate.

Determine the congruent validity and intra- and inter-day reliability of RMR measures assessed by the ParvoMedics Trueone 2 400 hood dilution method (Parvo) and Cosmed K4b(2) (Cosmed) breath-by-breath metabolic systems. Participants underwent 6 RMR assessments over 2 consecutive mornings, 3 with the Parvo (Day 1: Parvo 1; Day 2: Parvo 2, 3), 3 with the Cosmed (Day 1: Cosmed 1; Day 2: Cosmed 2, 3). Measured VE, FEO(2), FECO(2), VO(2), VCO(2), kcal/day, and HR values were averaged over a minimum of 10 min. Intra- and inter-day reliability within each system was determined with RMANOVA, and congruent validity was assessed via paired sample t-tests.31 participants (13 females, 18 males; 27.3±7 years, 24.8±3.1 kg.m(2)) completed the study. There were no significant differences in any within or between day Parvo values or Cosmed values. When systems were compared, there was a significant difference between VE (Parvo2: 25.03 L/min, Cosmed2: 8.98 L/min) and FEO(2) (Parvo2: 19.68%, Cosmed2: 16.63%), however, there were no significant difference in device-calculated RMR (kcals/day).The Parvo and Cosmed are reliable metabolic system with no intra- or inter-day differences in RMR. Due to differences in measurement technology, FEO(2), V(E) were significantly different between systems, but the resultant RMR values were not significantly different.

Comprehensive simultaneous shipboard and airborne characterization of exhaust from a modern container ship at sea.

We report the first joint shipboard and airborne study focused on the chemical composition and water-uptake behavior of particulate ship emissions. The study focuses on emissions from the main propulsion engine of a Post-Panamax class container ship cruising off the central coast of California and burning heavy fuel oil. Shipboard sampling included micro-orifice uniform deposit impactors (MOUDI) with subsequent off-line analysis, whereas airborne measurements involved a number of real-time analyzers to characterize the plume aerosol, aged from a few seconds to over an hour. The mass ratio of particulate organic carbon to sulfate at the base of the ship stack was 0.23 +/- 0.03, and increased to 0.30 +/- 0.01 in the airborne exhaust plume, with the additional organic mass in the airborne plume being concentrated largely in particles below 100 nm in diameter. The organic to sulfate mass ratio in the exhaust aerosol remained constant during the first hour of plume dilution into the marine boundary layer. The mass spectrum of the organic fraction of the exhaust aerosol strongly resembles that of emissions from other diesel sources and appears to be predominantly hydrocarbon-like organic (HOA) material. Background aerosol which, based on air mass back trajectories, probably consisted of aged ship emissions and marine aerosol, contained a lower organic mass fraction than the fresh plume and had a much more oxidized organic component. A volume-weighted mixing rule is able to accurately predict hygroscopic growth factors in the background aerosol but measured and calculated growth factors do not agree for aerosols in the ship exhaust plume. Calculated CCN concentrations, at supersaturations ranging from 0.1 to 0.33%, agree well with measurements in the ship-exhaust plume. Using size-resolved chemical composition instead of bulk submicrometer composition has little effect on the predicted CCN concentrations because the cutoff diameter for CCN activation is larger than the diameter where the mass fraction of organic aerosol begins to increase significantly. The particle number emission factor estimated from this study is 1.3 x 10(16) (kg fuel)(-1), with less than 1/10 of the particles having diameters above 100 nm; 24% of particles (>10 nm in diameter) activate into cloud droplets at 0.3% supersaturation.