Synchronized External Pulsation for Improved Tolerance to Acceleration Stress: Model Studies and Preliminary Experiments

Synchronized external pulsation is proposed as a method to improve tolerance to acceleration stress. This technique uses a modified anti-G suit which is pressurized and depressurized synchronously with the heart cycle. The feasibility of the procedure has been studied using a computer model of the cardiovascular system which includes the effects of Gz stress, and contains simulations of baroreceptor control of heart rate and venous tone. Model predictions indicate that for unprotected subjects, carotid pressure at eye level (ophthalmic artery pressure) decreases to 20 mmHg (beginning of central light loss) at approximately +3.6 Gz. Applying standard anti-G suit pressure to the model increases this level to 5.3 Gz. When synchronized external pulsation of 2 psi is superimposed on the standard anti-G suit pressure, the tolerance to acceleration stress is further augmented by at least 0.9 G above the protection afforded by the standard anti-G suit alone. A set of preliminary experiments on human subjects to test the feasibility of using the technique in the high-G environment has also been carried out. The results under various protection modes compare favorably to the model predictions. Our results suggest that the computer model presented here is a useful tool for studying cardiovascular responses under +GZ stress. It also indicates that using synchronized external pulsation pressure superimposed on the standard anti-G suit pressure may offer extra protection to acceleration stress.     

On the Bieberbach conjecture for functions with a small second coefficient

In the following we prove that for a given univalent function such that |a ₂|<1.05, |a _n|<n for eachn. This is an improvement of the result in [1].     

An axiomatization of the egalitarian solutions

The egalitarian solutions for general cooperative games which were defined and axiomatized by Kalai and Samet, are compared to the Harsanyi solution. It is shown that axioms used by Hart to characterize the Harsanyi solution can be used to characterize the (symmetric) egalitarian solution. The only changes needed are the omission of the scale covariance axiom and the inclusion, in the domain of the solution, of games which lack a certain smoothness requirement.     

Capacitance voltage characterization of poly SiSiO2Si structures

The high frequency C-V characteristics of poly SiSiO₂Si capacitors have been studied. It is shown that the poly SiSiO₂Si capacitor C-V characteristics are significantly different from the corresponding metal-SiO₂Si capacitor due to field penetration into the poly Si layer. A comparison of the theoretical and measured C-V characteristics gives an estimate of the surface state charge density at the poly SiSiO₂ interface and indicates that the surface potential behavior of this interface is trap and surface state dominated up to poly silicon impurity concentrations of approximately 10¹⁷ cm^?3.