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At least 1,045 records · Page 58Linked to original sources
PubMedDate not supplied

Space radiation dose estimates on the surface of Mars.

A future goal of the U.S. space program is a commitment to the manned exploration and habitation of Mars. An important consideration of such missions is the exposure of crew members to the damaging effects of ionizing radiation from high-energy galactic cosmic ray fluxes and solar proton flares. The crew will encounter the most harmful radiation environment in transit to Mars from which they must be adequately protected. However, once on the planet's surface, the Martian environment should provide a significant amount of protection from free-space radiative fluxes. In current Mars scenario descriptions, the crew flight time to Mars is estimated to be anywhere from 7 months to over a year each way, with stay times on the surface ranging from 20 days to 2 years. To maintain dose levels below established astronaut limits, dose estimates need to be determined for the entire mission length. With extended crew durations on the surface anticipated, the characterization of the Mars radiation environment is important in assessing all radiation protection requirements. This synopsis focuses on the probable doses incurred by surface inhabitants from the transport of galactic cosmic rays and solar protons through the Mars atmosphere.

Astronauts↗
PubMedDate not supplied

Martian regolith as space radiation shielding.

In current Mars scenario descriptions, an entire mission is estimated to take 500-1000 days round trip with a 100-600 day stay time on the surface. To maintain radiation dose levels below permissible limits, dose estimates must be determined for the entire mission length. With extended crew durations anticipated on Mars, the characterization of the radiation environment on the surface becomes a critical aspect of mission planning. The most harmful free-space radiation is due to high energy galactic cosmic rays (GCR) and solar flare protons. The carbon dioxide atmosphere of Mars has been estimated to provide a sufficient amount of shielding from these radiative fluxes to help maintain incurred doses below permissible limits. However, Mars exploration crews are likely to incur a substantial dose while in transit to Mars that will reduce the allowable dose that can be received while on the surface. Therefore, additional shielding may be necessary to maintain short-term dose levels below limits or to help maintain career dose levels as low as possible. By utilizing local resources, such as Martian regolith, shielding materials can be provided without excessive launch weight requirements from Earth. The scope of this synopsis and of Ref. 3 focuses on presenting our estimates of surface radiation doses received due to the transport and attenuation of galactic cosmic rays and February 1956 solar flare protons through the Martian atmosphere and through additional shielding provided by Martian regolith.

Atmosphere↗
PubMed1994

Uveal melanoma: is solar ultraviolet radiation a risk factor?

Age-standardized mortality rates for cancers of the eye among adults in England and Wales are compared with those for cutaneous malignant melanoma. While cutaneous malignant melanoma rates have increased three-fold since 1950-54, rates for cancers of the eye have remained relatively constant over the same period. Collectively, the inconclusive findings of case-control studies for an association between exposure to ultraviolet radiation and uveal melanoma, the lack of supporting dosimetry data, together with the lack of an upward trend in mortality rates for cancers of the eye, suggests that exposure to ultraviolet radiation may not be a major factor in the etiology of uveal melanoma.

Adult↗
PubMed1998

Modern cosmology and the origin of our three dimensionality.

We are three dimensional egocentric beings existing within a specific space/time continuum and dimensionality which we assume wrongly is the same for all times and places throughout the entire universe. Physicists name Omnipoint the origin of the universe at Dimension zero, which exploded as a Big Bang of energy proceeding at enormous speed along one dimension which eventually curled up into matter: particles, atoms, molecules and Galaxies which exist in two dimensional space. Finally from matter spread throughout the cosmos evolved life generating eventually the DNA molecules which control the construction of brains complex enough to construct our three dimensional Body Representation from which is extrapolated what we perceive as a 3-D universe. The whole interconnected structures which conjure up our three dimensionality are as fragile as Humpty Dumpty, capable of breaking apart with terrifying effects for the individual patient during a psychotic panic, revealing our three dimensionality to be but "maya", an illusion, which we psychiatrists work at putting back together.

Brain↗
PubMed1999

How to protect your eyes from solar retinopathy.

On August 11, in Belgium a solar eclipse will occur which will be total in the Southern area of the country. Although the observation of a solar eclipse is an intriguing phenomenon, inappropriate shielding from the sunlight can cause irreversible ocular lesions. Besides good absolute absorption of visible light, a blocking of ultraviolet and infrared light is equally important. In this study, four homemade sun filters were tested: a soot-blackened piece of glass, a black unexposed developed slide film, an audio-CD and a recordable CD-ROM. Also two commercially available filters were investigated: eclipse-shades and mylar foil. The soot-blackened glass and black slide film slip were highly transparent for infrared light, making them dangerous for solar observation. The recordable CD-ROM was too transparent for visible light to serve as solar filter, while the audio-CD tested absorbed enough visible, ultraviolet and infrared light to make it suitable for eclipse viewing. However, many types of audio-CD's are available making it impossible for the observer to know if a given CD is safe to use for solar viewing. Both commercially available solar filters tested had a good absolute visible light absorption, as well as an equally good absorption of ultraviolet and infrared light, making them safe for eclipse observation.

Belgium↗
PubMedDate not supplied

The planetary positions and relationships at the dates of birth of a cohort of Nigerian schizophrenics.

Some astrological hypotheses related to predisposition to severe mental illness were tested by analysing the zodiacal signs, the interactions between planetary qualities (aspects), and the occurrence of full and new moon dates, on the dates of birth of 221 schizophrenics, compared with 112 normal subjects. The sun signs of the schizophrenics were significantly more likely to be in the signs associated with introversion, while those of the control population were significantly more likely to be in the outgoing signs. A significantly higher proportion of schizophrenics had their Mars (i.e., symbol of aggressiveness) in the outgoing signs than the normal population. A significantly higher proportion of control subjects fulfilled operational criteria for adequacy of number of aspects between the sun and the other planets. The tendency for a higher proportion of schizophrenics to have "difficult" aspects just failed to reach significance. A significantly higher proportion of control subjects had aspects between the sun and mars; and also a significantly higher proportion of control subjects had "soft" (helpful) aspects between the sun and mars. These findings are in keeping with the well-known oddity of schizophrenia (schiz = split; phren = mind); such that, a group which collectively is characterised by an "introverted" self (i.e. sun sign), has a coexisting aggressive tendency (i.e. strong mars) and poor integration between the elements of the psyche and the self (i.e. inadequacy of aspects between Sun and other planets). However, the findings give only partial support to key astrological postulates because there was a non-significant trend for more schizophrenics to be born in "water" signs and on full moon dates.

Astrology↗
PubMed1999

Risking the eclipse.

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Astronomical Phenomena↗
PubMed1999

Solar care.

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Emergency Nursing↗
PubMedDate not supplied

Astral links.

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Emergency Nursing↗
PubMed1999

Much ado about nothing.

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Anniversaries and Special Events↗
PubMed2001

Let's go to Mars!

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Aerospace Medicine↗
PubMed1992

Chemical studies on the existence of extraterrestrial life.

Although the search for extraterrestrial intelligence has not produced any direct evidence of extraterrestrial life, the emergence of life on Earth, which appears to be controlled by universal laws of physics and chemistry, must have been repeated elsewhere in the universe. The experimental approaches in our laboratory to understand the origin of life on the Earth are summarized in an attempt to obtain a better insight into the chemical basis of extraterrestrial life.

Amino Acids↗