Ground-based research on vestibular adaption to G-level transitions

Dit artikel beschrijft de nieuwste resultaten van het ESA onderzoeksproject 'Motion perception' waarbij de correlatie wordt onderzocht tussen de gevoeligheid van astronauten voor Space Adaption Syndrome (SAS) en Sickness Induced by Centrifugation (SIC

Subjective Estimates of G-load in Centrifuge-Based Simulation and Applications for G-cueing in Desdemona

In centrifuge simulators pilots experience the G-forces and fast G-onsets encountered in the real fighter aircraft. The motion cueing principle that drives these simulators is based on creating G-forces by increasing the centripetal force of the centrifuge through a rotation of the simulator arm. The centrifuge usually spins at a constant 1.4 G baseline G-level when the aircraft is level and stationary. Ideally, the motion cueing algorithm presents to pilots a G-vector that is equal to the real one both in direction and amplitude. This motion cueing principle assumes that the pilots perceive any deviation from the desired G-load. If this is not true, one could reduce the high angular accelerations/decelerations of the centrifuge arm since there is no need to reach the exact airplane G-load. This would then reduce the negative side-effects (like motion sickness) that come from the high angular accelerations/decelerations in short-radius centrifuges. We investigated the just noticeable differences (JND) in the perception of G-load magnitude. The study was conducted in the Desdemona research simulator where eleven subjects participated in the experiment. Subjects actively had to reproduce a G-load that was passively presented to them. Two G-loads were presented to the subjects (1.6 G and 1.8 G). Results showed that subjects have a better accuracy in reproducing the 1.6 G than the 1.8 G condition. This indicates that the JND in perceiving the magnitude of the G-load is related with the G-load intensity. Copyright © 2009 by the American Institute of Aeronautics and Astronautics, Inc

How to use body tilt for the simulation of linear self motion

We examined to what extent body tilt may augment the perception of visually simulated linear self acceleration. Fourteen subjects judged visual motion profiles of fore-aft motion at four different frequencies between 0.04-0.33 Hz, and at three different acceleration amplitudes (0.44, 0.88 and 1.76 m/s2). Simultaneously, subjects were tilted backward and forward about their pitch axis. The amplitude of pitch tilt was systematically varied. Using a two-alternative-forced-choice paradigm, psychometric curves were calculated in order to determine: 1) the minimum tilt amplitude required to generate a linear self-motion percept in more than 50% of the cases, and 2) the maximum tilt amplitude at which rotation remains sub-threshold in more than 50% of the cases. The results showed that the simulation of linear self motion became more realistic with the application of whole body tilt, as long as the tilt rate remained under the detection threshold of about 3 deg/s. This value is in close agreement with the empirical rate limit commonly used in flight simulation. The minimum required motion cue was inversely proportional to stimulus frequency, and increased with the amplitude of the visual displacement (rather than acceleration). As a consequence, the range of useful tilt stimuli became more critical with increasing stimulus frequency. We conclude that this psychophysical approach reveals valid parameters for motion driving algorithms used in motion base simulators.

The versatile transcription factor Oct-1 : a crucial protein in embryonic development and a key component of the stress cellular response

Oct-1 is a transcription factor belonging to the POU family (Clerc et al. 1988) (Herr et al. 1988) (Ryan and Rosenfeld 1997). The members of this family are involved in a broad range of biological processes like transcription of housekeeping genes (Oct-1), pluripotency of embryonic stem cells (Oct-4) or development of immune system (Oct-1, Oct-2) (Spaniol et al. 1996). The transcription factor Oct-1 is ubiquitously expressed in embryonic and adult tissues, and regulates the expression of a variety of genes. Previous studies described Oct-1 to be regulated at the protein level by phosphorylation in a cell cycle dependent manner. In addition, more recently it has been shown that Oct- 1 is induced in response to DNA damage and modulates the activity of genes like GADD45 important for the cellular stress response (Segil et al. 1991) (Zhao et al. 2000) (Jin et al. 2001) (Fan et al. 2002) (Tantin et al. 2005).. Knockout and a conditional oct-1 knockout alleles were created in our laboratory, and used to generate Oct-1 deficient mouse embryonic fibroblast (MEFs) and embryonic stem cells (ES). We used them as a model to study the cellular response to stress in absence of Oct-1. We have found that cells lacking Oct-1 were less sensitive to stress lik

Ground-based research on vestibular adaption to G-level transitions

Dit artikel beschrijft de nieuwste resultaten van het ESA onderzoeksproject 'Motion perception' waarbij de correlatie wordt onderzocht tussen de gevoeligheid van astronauten voor Space Adaption Syndrome (SAS) en Sickness Induced by Centrifugation (SIC

Orientation of Listings plane after hypergravity in humans

De mens kan zich aanpassen aan nieuwe zwaartekrachtsniveaus (gewichtloosheid, maan, mars, ... en ook in een centrifuge). Uit dit onderzoek blijkt dat ook uit de manier waarop we onze ogen bewegen, wat ons weer meer inzicht geeft in de referentie-kaders die ons centraal zenwustelsel gebruikt voor het inschatten van zelfbeweging en -orientatie t.o.v. de zwaartekrach

Pilot performance in centrifuge-based simulation of unusual attitude recovery

This paper describes two simulator experiments studying how accurately pilots can judge and reproduce specific g loads and how their control behavior depends on the sensation of physical g loads during unusual attitude recovery. Seventeen commercial pilots participated. The first experiment shows that pilots tend to overestimate g loads, resulting in performance below the target g load. With brief training, their performance instantly improved up to adequate levels. However, a retest after 6 months shows that this improvement did not endure. The second experiment shows that centrifuge-based g cueing helps pilots to recover from a nose-low unusual attitude, with significantly smaller deviations and within the limit load, whereas in the fixed-base condition they tend to pull almost 20% too much g load. It is concluded that physical g cueing results in improved upset recovery control and may contribute to more realistic and adequate recovery training. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved

Potential non-pharmacological countermeasures for motion sickness

Motion sickness can occur in any motion environment to which a person is not adapted, varying from cars, boats, and planes to fun rides and virtual reality. With symptoms such as nausea, vomiting, headache, lethargy, dizziness, and loss of concentration it causes discomfort for passengers but also a decrease in task performance for crew. Although several pharmacological countermeasures exist, these invariably have side-effects which may also affect someone’s performance. The objective of this theoretical study was to identify alternative, non-pharmacological methods against motion sickness, and to provide recommendations for possible explorative experiments in follow-up work. The emphasis was on non-invasive, behavioral and cognitive methods. The work consisted of a review of literature on non-pharmacological countermeasures, as well as a workshop with experts from various behavioral sciences. An important outcome of the study is to provide recommendations for explorative experiments in follow-up work to increase our understanding of physiological, psychological, and behavioral factors affecting motion sickness