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Unusual vestibular responses to head movements in weightlessness may produce spatial orientation illusions and symptoms of space motion sickness. An integrated set of experiments was performed during Spacelab 1, as well as before and after the flight, to evaluate responses mediated by the otolith organs and semicircular canals. A variety of measurements(More)
(1) Gating currents were recorded from frog nodes of Ranvier treated either with toxins III or IV from the venom of the scorpion Centruroides sculpturatus or with the alkaloid toxin aconitine. (2) Toxins III or IV from Centruroides sculpturatus (which drastically reduce the sodium permeability PNa and slightly shift its voltage dependence in the(More)
In voltage clamped nodes of Ranvier inactivation of the sodium permeability is slowed by toxin V from the scorpion Centruroides sculpturatus, by sea anemone toxin ATX II or by internally applied KIO3. The slow decay of the Na inward current is markedly accelerated if the test pulse is preceded by a depolarizing conditioning pulse followed by a 10-500 ms(More)
It is evident from the data reviewed that scorpion toxins can be distinguished on the basis of three properties: their effects on Na currents, their specific binding to excitable membranes, and the effects of depolarization and pH on binding and on effect. Additional work with other scorpion toxins is required to establish the degree of correlation between(More)
Reflex responses that depend on human otolith organ sensitivity were measured before, during and after a 10 day space flight. Otolith-spinal reflexes were elicited by means of sudden, unexpected falls. In weightlessness, "falls" were achieved using elastic cords running from a torso harness to the floor. Electromyographic (EMG) activity was recorded from(More)
BACKGROUND Watt et al. (15) and Young et al. (17) have demonstrated that during prolonged microgravity, large errors can be made when pointing at memorized targets in the absence of vision. However, those experiments could not distinguish between errors caused by not knowing where the arm was pointed and errors caused by not knowing target location. The(More)
Following a 30-minute exposure to an unusual motor strategy called "Torso Rotation" (TR), the signs and symptoms of motion sickness appear along with perceptual illusions during movement, gaze and postural instability, and a significantly reduced vestibulo-ocular response (VOR) gain. With repeated exposure to TR, the motion sickness disappears and gaze(More)
Experiments on human spatial orientation were conducted on four crewmembers of Space Shuttle Spacelab Mission 1. This introductory paper presents the conceptual background of the project, the relationship among the experiments and their relevance to a "sensory reinterpretation hypothesis". Detailed experiment procedures and results are presented in the(More)
1. The effect of various toxin fractions isolated by Watt et al. (1978) from the venom of the scorpion Centruroides sculpturatus Ewing on the Na currents of the node of Ranvier has been studied with the voltage clamp method. 2. The toxin fractions were applied externally. The most potent fractions were toxins III, IV and V which were effective in(More)
This paper discusses how simulation was used to evaluate and characterize the scheduling issues in a semiconductor fab and the subsequent implementation of an integrated scheduling solution. The scheduling system was integrated with the fab MES and a number of other data sources including an integrated machine standards database, preventative maintenance(More)