Survey of needs and capabilities for wind tunnel testing of dynamic stability of aircraft at high angles of attack

A survey was conducted relative to future requirements for dynamic stability information for such aerospace vehicles as the space shuttle and advanced high performance military aircraft. High-angle-of-attack and high-Reynolds number conditions were emphasized. A review was made of the wind-tunnel capabilities in North America for measuring dynamic stability derivatives, revealing an almost total lack of capabilities that could satisfy these requirements. Recommendations are made regarding equipment that should be constructed to remedy this situation. A description is given of some of the more advanced existing capabilities, which can be used to at least partly satisfy immediate demands

Cytoprotective effect of lithium against spontaneous and induced apoptosis of lymphoid cell line MOLT-4.

Lithium (Li) is still useful in the treatment of bipolar disorder. Cellular mechanisms of Li action are not fully understood and include some cytoprotective properties. Data concerning Li effect on the apoptotic mechanisms in cells other than neurons are fragmentary and contradictory. We have investigated anti-apoptotic activity of Li in a lymphoid derived MOLT-4 cell line. Spontaneous and camptothecin-induced apoptosis was analyzed in cells treated with 0-20 mM Li carbonate. Early apoptosis was identified as significant mitochondrial depolarization (JC-1 staining). Later stages of apoptosis were estimated with annexin V binding and by the proportion of cells containing sub-G1 amounts of DNA (PI staining). We have observed a biphasic effect of Li on the proportion of spontaneously apoptotic cells;namely, low (therapeutic) concentrations of Li had a significant effect stabilizing the mitochondrial membrane polarization, while 10 and 20mM Li increased apoptosis. The latter could be seen both as mitochondrial depolarization as well as an increased proportion of sub-G1 cells, accompanied by reduced proportion of S phase cells. Li at concentrations above 2 mM had a significant, dose-dependent, anti-apoptotic effect on the cells undergoing camptothecin induced apoptosis. In conclusion, demonstrated cytoprotective effect of Li is at least partially related to stabilization of mitochondrial membrane potential and to the reduction of DNA damaging effects in proliferating cells; both may form part of the mechanism through which Li is useful in therapy of bipolar disorder, but may have more general consequences

Cytoprotective effect of lithium against spontaneous and induced apoptosis of lymphoid cell line MOLT-4.

Lithium (Li) is still useful in the treatment of bipolar disorder. Cellular mechanisms of Li action are not fully understood and include some cytoprotective properties. Data concerning Li effect on the apoptotic mechanisms in cells other than neurons are fragmentary and contradictory. We have investigated anti-apoptotic activity of Li in a lymphoid derived MOLT-4 cell line. Spontaneous and camptothecin-induced apoptosis was analyzed in cells treated with 0-20 mM Li carbonate. Early apoptosis was identified as significant mitochondrial depolarization (JC-1 staining). Later stages of apoptosis were estimated with annexin V binding and by the proportion of cells containing sub-G1 amounts of DNA (PI staining). We have observed a biphasic effect of Li on the proportion of spontaneously apoptotic cells;namely, low (therapeutic) concentrations of Li had a significant effect stabilizing the mitochondrial membrane polarization, while 10 and 20mM Li increased apoptosis. The latter could be seen both as mitochondrial depolarization as well as an increased proportion of sub-G1 cells, accompanied by reduced proportion of S phase cells. Li at concentrations above 2 mM had a significant, dose-dependent, anti-apoptotic effect on the cells undergoing camptothecin induced apoptosis. In conclusion, demonstrated cytoprotective effect of Li is at least partially related to stabilization of mitochondrial membrane potential and to the reduction of DNA damaging effects in proliferating cells; both may form part of the mechanism through which Li is useful in therapy of bipolar disorder, but may have more general consequences

A Novel Force Control Traverse for Simulating UAV Flight in a Wind Tunnel

Wind tunnel testing methods often infer aerodynamic performance via quasi-steady predictions, driving a wind tunnel model through predetermined trajectories, or quasi- steady integration of the applied aerodynamic forces and moments. This paper focuses on a new testing approach that allows the simulation and study of the true longitudinal dynamics of a wind tunnel model. The system design allows an experimentalist to carry heavy models with all of the needed sensors for evaluating true unsteady aerodynamic flight qualities. Controlling the forces and moments applied to the model allows the experimentalist to remove effects such as gravity and traverse friction. Using feedback on the applied force and moments, the dynamic characteristics of the model can be actively modified to alter dynamic characteristics such as the system's natural frequency, damping, c.g. location, and/or effective model inertia. All dynamic effects can be set arbitrarily but must be within traverse limits. The model does not have to be balanced because the control system actively restricts motion to be within the longitudinal plane. An example experimental simulation flight is shown using a NACA 4415 wing section with a servo motor in torque mode to simulate the effect of a conventional tail surface. Copyright © 2008 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved