Mechanical design of NASA Ames Research Center vertical motion simulator

NASA has designed and is constructing a new flight simulator with large vertical travel. Several aspects of the mechanical design of this Vertical Motion Simulator (VMS) are discussed, including the multiple rack and pinion vertical drive, a pneumatic equilibration system, and the friction-damped rigid link catenaries used as cable supports

Reducing complexity and unidentifiability when modelling human atrial cells

Mathematical models of a cellular action potential in cardiac modelling have become increasingly complex, particularly in gating kinetics which control the opening and closing of individual ion channel currents. As cardiac models advance towards use in personalised medicine to inform clinical decision-making, it is critical to understand the uncertainty hidden in parameter estimates from their calibration to experimental data. This study applies approximate Bayesian computation to re-calibrate the gating kinetics of four ion channels in two existing human atrial cell models to their original datasets, providing a measure of uncertainty and indication of potential issues with selecting a single unique value given the available experimental data. Two approaches are investigated to reduce the uncertainty present: re-calibrating the models to a more complete dataset and using a less complex formulation with fewer parameters to constrain. The re-calibrated models are inserted back into the full cell model to study the overall effect on the action potential. The use of more complete datasets does not eliminate uncertainty present in parameter estimates. The less complex model, particularly for the fast sodium current, gave a better fit to experimental data alongside lower parameter uncertainty and improved computational speed

Active Mass Under Pressure

After a historical introduction to Poisson's equation for Newtonian gravity, its analog for static gravitational fields in Einstein's theory is reviewed. It appears that the pressure contribution to the active mass density in Einstein's theory might also be noticeable at the Newtonian level. A form of its surprising appearance, first noticed by Richard Chase Tolman, was discussed half a century ago in the Hamburg Relativity Seminar and is resolved here.Comment: 28 pages, 4 figure

Perspectives, Challenges, and Opportunities: The Pandemic Teaching Experiences in Science Courses

The shift to distance learning has created unique perspectives and challenges to educational stakeholders specifically among teachers who are tasked with keeping teaching and learning on track despite their professional, technical, and personal concerns, and inadequate familiarity to the new learning modality. While these realities have been challenging the capability of teachers, they also open the doors for opportunities of levelling up to a new education landscape and harnessing potentials which may be useful for the furtherance of the teaching practices. The present qualitative study aims to document Science teachers’ perspectives, challenges and opportunities in the teaching of Science courses during the pandemic. It consists of the various insights, initiatives, coping strategies and actions, and opportunities of eight Filipino Science teachers towards securing a responsive and efficient learning management in the midst of the unforeseen challenges in the education sector brought by the impact of the COVID-19 pandemic