Modelling of natural convection flows with large temperature differences : a benchmark problem for low Mach number solvers. Part 1, Reference solutions

There are very few reference solutions in the literature on non-Boussinesq natural convection flows. We propose here a test case problem which extends the well-known De Vahl Davis differentially heated square cavity problem to the case of large temperature differences for which the Boussinesq approximation is no longer valid. The paper is split in two parts: in this first part, we propose as yet unpublished reference solutions for cases characterized by a non-dimensional temperature difference of 0.6, (constant property and variable property cases) and (variable property case). These reference solutions were produced after a first international workshop organized by CEA and LIMSI in January 2000, in which the above authors volunteered to produce accurate numerical solutions from which the present reference solutions could be established

Cell alkalinization is not necessary and increased sodium influx is not sufficient for stimulated superoxide production

AbstractPreincubation of rabbit neutrophils for 5 min with the protein kinase C inhibitor H7 causes inhibition of the rise in intracellular pH but not the increase in Na+ influx or stimulated oxidative burst produced by the chemotactic factor formyl-methionyl-leucyl-phenylalanine. On the other hand, the stimulated superoxide production, but not the increase in Na+ influx produced by phorbol 12-myristate 13-acetate, is inhibited by H7. The effect is more pronounced on the rate than the extent of the stimulated superoxide release. Furthermore, cell acidification produced by the phorbol ester but not by the chemotactic factor is decreased in the presence of H7. These results suggest that (i) most of the stimulated Na+ influx is not coupled to H+ efflux, (ii) in the case of the chemoattractant, the rise in intracellular pH is not necessary for stimulated superoxide production, (iii) the increase in Na+influx, in the case of the phorbol ester, is not sufficient for the stimulation of the oxidative burst, and (iv) the sources of the H+ responsible for the stimulated pH drop are the various metabolic activities of the cell, including NADPH oxidation and activation of the hexose monophosphate shunt

Extended performance solar electric propulsion thrust system study. Volume 4: Thruster technology evaluation

Several thrust system design concepts were evaluated and compared using the specifications of the most advanced 30 cm engineering model thruster as the technology base. Emphasis was placed on relatively high power missions (60 to 100 kW) such as a Halley's comet rendezvous. The extensions in thruster performance required for the Halley's comet mission were defined and alternative thrust system concepts were designed in sufficient detail for comparing mass, efficiency, reliability, structure, and thermal characteristics. Confirmation testing and analysis of thruster and power processing components were performed, and the feasibility of satisfying extended performance requirements was verified. A baseline design was selected from the alternatives considered, and the design analysis and documentation were refined. The baseline thrust system design features modular construction, conventional power processing, and a concentrator solar array concept and is designed to interface with the Space Shuttle

Longitudinal Changes in the Oxygen Uptake Kinetic Response to Heavy-Intensity Exercise in 14- to 16-Year-Old Boys

There is another ORE record for this publication: http://hdl.handle.net/10036/3830This study examined longitudinal changes in the pulmonary oxygen uptake (p(V) over dotO(2)) kinetic response to heavy-intensity exercise in 14-16 yr old boys. Fourteen healthy boys (age 14.1 +/- 0.2 yr) completed exercise testing on two occasions with a 2-yr interval. Each participant completed a minimum of three 'step' exercise transitions, from unloaded pedalling to a constant work rate corresponding to 40% of the difference between the (p(V) over dotO(2)) (2), at the gas exchange threshold and peak (p(V) over dotO(2)) , (40% A). Over the 2-yr period a significant increase in the phase II time constant (25 5 vs. 30 +/- 5 s; p = .002, omega(2) = 0.34), the relative amplitude of the (p(V) over dotO(2)) slow component (9 +/- 5 vs. 13 +/- 4%; p = .036, omega(2) = 0.14) and the(p(V) over dotO(2)) gain at end-exercise (11.6 +/- 0.6 vs. 12.4 +/- 0.7 mL.min(-1).W-1; p < .001, omega(2) = 0.42) were observed. These data indicate that the control of oxidative phosphorylation in response to heavy-intensity cycling exercise is age-dependent in teenage boys

Multi-Scale Simulation Modeling for Prevention and Public Health Management of Diabetes in Pregnancy and Sequelae

Diabetes in pregnancy (DIP) is an increasing public health priority in the Australian Capital Territory, particularly due to its impact on risk for developing Type 2 diabetes. While earlier diagnostic screening results in greater capacity for early detection and treatment, such benefits must be balanced with the greater demands this imposes on public health services. To address such planning challenges, a multi-scale hybrid simulation model of DIP was built to explore the interaction of risk factors and capture the dynamics underlying the development of DIP. The impact of interventions on health outcomes at the physiological, health service and population level is measured. Of particular central significance in the model is a compartmental model representing the underlying physiological regulation of glycemic status based on beta-cell dynamics and insulin resistance. The model also simulated the dynamics of continuous BMI evolution, glycemic status change during pregnancy and diabetes classification driven by the individual-level physiological model. We further modeled public health service pathways providing diagnosis and care for DIP to explore the optimization of resource use during service delivery. The model was extensively calibrated against empirical data.Comment: 10 pages, SBP-BRiMS 201