Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PHOSPHENE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources
PubMed2001

The ALTEA facility on the International Space Station.

The ALTEA project studies the problems related to possible functional damage to the Central Nervous System (CNS) due to particle radiation in space environment. The project is a large international and multi-disciplinary collaboration. The ALTEA instrumentation is an helmet-shaped multi-sensor device that will measure concurrently the dynamics of the functional status of the visual system and the passage of each particle through the brain within a pre-determined energy window. ALTEA is scheduled to fly in the International Space Station in February 2003. One part of the multi-sensor device, one of the advanced silicon telescopes, will be launched in the ISS in early 2002 and serve as test for the final device and as discriminating dosimeter for the particle fluences within the ISS.

Aerospace Medicine↗
PubMed1977

Comparison of the light-flash phenomena observed in space and in laboratory experiments.

Astronauts on Apollo and Skylab missions have reported observing a variety of visual phenomena when their eyes were closed and adapted to darkness. These observations were studied under controlled conditions during a number of sessions on board Apollo and Skylab spacecraft and the data available to date on these so-called light flashes are in the form of descriptions of the phenomena and frequency of occurrence. Similar visual phenomena have been demonstrated in a number of laboratories by exposing the eyes of human subjects to beams of neutrons, alpha particles, pions and protons. More than one physical mechanism is involved in the laboratory and space phenomena. No direct comparison of the laboratory and space observations has been made by observers who have experienced both. However, the range of visual phenomena observed in the laboratory is consistent with the Apollo and Skylab observations. Measured detection efficiencies can be used to estimate the frequencies with which various phenomena would be observed if that subject was exposed to cosmic rays in space.

Cosmic Radiation↗
PubMed1977

Apollo-Soyuz light-flash observations.

While dark adapted, two Apollo-Soyuz astronauts saw eighty-two light flash events during a complete 51 degrees orbit which passed near the north magnetic pole and through the South Atlantic Anomaly. The frequency of events at the polar parts of the orbit is 25 times that noted in equatorial latitudes and no increased frequency was noted in the South Atlantic Anomaly at the 225-km altitude. The expected flux of heavy particles at the northern and southern points is 1-2 min-1 per eye, and the efficiency for seeing HZE particles which were below the Cerenkov threshold is 50%.

Arctic Regions↗
PubMed1973

Biological effects due to single accelerated heavy particles and the problems of nervous system exposure in space.

The use of accelerated nitrogen and oxygen nuclei with 270 MeV nucleon-1 at the Berkeley Bevatron allowed a beginning to be made of systematic studies of the effects of heavy particles in multicellular organisms. Initial studies will be briefly reviewed. Individual nitrogen particles produced definite light flashes, streaks and interrupted streaks when they crossed light-sensitive parts of the human retina. The possible hazard from primary heavy galactic cosmic ray particles on long-term space flights are discussed, with special attention to the nervous system.

Animals↗
PubMed1973

On the effect of ionizing radiation upon the retina in man and animals.

The phenomenon of light flashes observed by the American cosmonauts on exposure to primary cosmic radiation during translunar flights, and also perceived by other observers on exposure of the eye to neutrons from accelerators, is indeed one of the latest manifestations of the sensitivity of the retina to very high energy radiation. The usual interpretations of this phenomenon are based either on the hypothesis of Vavilov-Cherenkov radiation in the ocular media, or on the direct stimulation of photoreceptors in the retina itself. The data available are submitted to adequate analysis, the experimental materials concerning the radiobiology of the retina are generalized, and a conclusion is drawn as to the most probable mechanism of light flashes considered as signals damaging the outer segments of the rods by particles arising from nuclear reactions in the retina.

Animals↗
PubMedDate not supplied

[Ocular effects of cosmic rays on the eyes].

The observed visual phenomena developing in humans as a result of the impact of heavy ions on the eye have been summarized. Possible mechanisms of these effects are discussed.

Cosmic Radiation↗
PubMedDate not supplied

[Interrelation of visual and auditory analyzer functions during extreme stimulation].

By psychophysiological methods the effect of intensive photostimulation on the functional state of the optic analyzer and the influence of extreme optic stimulus on the hearing function were studied. An impulse acoustic stimulus contributed to the recovery of peripheral light sensitivity, left unchanged the central light sensitivity, improved acuity of color distinction, expanded the field of vision of red and green colors and reduced electric sensitivity and critical frequency of disappearance of light flashes. After an exposure to a superbright flash a decrease of absolute thresholds of hearing, electric sensitivity and critical frequency of fusion of electric stimulation of the acoustic analyzer was detected. These data give evidence that sensitivity of one analyzer can be increased by means of short-term intensive stimulation of the other.

Acoustic Stimulation↗
PubMed1977

Role of nuclear stars in the light flashes observed on Skylab 4.

The astronauts on Skylab 4 observed bursts of intense visual light-flash activity when their spacecraft passed through the portion of the earth's inner trapped radiation belt known as the South Atlantic Anomaly (SAA). Two experimental sessions were carried out on board Skylab 4 under the auspices of Pinsky et al. who compare the flash rates with the measured flux of Z > or = 1 particles that would pass through the astronaut's eyes. They concluded that the flash rates, which became as great as 20/min, were anomalously high. We explored a number of alternative explanations for the anomalous flash rates that would be consistent with the accepted SAA flux values and the laboratory data on particle induced visual sensations and found that when one includes the effect of nuclear interactions in and near the retina which result in star formation (the emission of slow protons, neutrons and alpha particles form the nucleus in an evaporation-like process) the apparent anomaly is removed.

Aerospace Medicine↗
PubMed1976

Role of Cerenkov radiation in the eye-flashes observed by Apollo astronauts.

Visual phenomena in the form of colorless flashes of light were observed by astronauts in deep space when their eyes were closed and adapted to darkness. We describe in this paper laboratory experiments and calculations which indicate that many of these flashes are the result of visible light generated within the astronauts' eyeball in the form of Cerenkov radiation when a relativistic HZE particle traverses it. The sensitivity to Cerenkov radiation measured for three subjects exposed to pulses of pions and muons and the visual phenomena observed were found to be consistent with the reports of flashes observed at rates as high as 2 per minute on Apollo missions 11 through 17.

Cosmic Radiation↗