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At least 721 records · Page 40Linked to original sources
PubMed1995

[Effects of radiation on man].

Living on Earth, man is subjected to a shower of radiation, of cosmic, telluric and internal origin. Variations in the level of radiation over time have left biological imprints; Man first learned about artificial radiation, then learned how to produce it, revolutionizing medical diagnosis and treatment, and producing huge quantities of energy, particularly electric energy. In les than a century, knowledge or radiobiology brought man to a good mastery of the use or radiation within precise norms. With the application of these norms, a corollary appeared: the halt in increasing incidences of cancer and leukemia, as had been the case for the pioneers in radiobiology at the beginning of the century. However, the notion persists that ionising radiation, even at insignificant doses, is dangerous for man. Recent advances concerning DNA repair, hormesis and cancerogenesis are reassuring with regard to the present standards The French Académie des Sciences has pronounced that the present rules "are prudent and ensure an appreciable margin of security".

Humans↗
PubMed2002

Studies about space radiation promote new fields in radiation biology.

Astronauts are constantly exposed to space radiation of various types of energy with a low dose-rate during long-term stays in space. Therefore, it is important to determine correctly the biological effects of space radiation on human health. Studies about biological the effects at a low dose and a low dose-rate include various aspects of microbeams, bystander effects, radioadaptive responses and hormesis which are important fields in radiation biology. In addition, space radiations contain high linear energy transfer (LET) particles. In particular, neutrons may cause reverse effectiveness at a low dose-rate in comparison to ionizing radiation. We are also interested in p53-centered signal transduction pathways involved in the cell cycle, DNA repair and apoptosis induced by space radiations. We must also study whether the relative biological effectiveness (RBE) of space radiation is affected by microgravity which is another typical component in space. To confirm this, we must prepare centrifuge systems in an International Space Station (ISS). In addition, we must prepare many types of equipment for space experiments in an ISS, because we cannot use conventional equipment from our laboratories. Furthermore, the research for space radiation might give us valuable information about the birth and evolution of life on the Earth. We can also realize the importance of preventing the ozone layer from depletion by the use of exposure equipment to sunlight in an ISS. For these reasons, we desire to educate space researchers of the next generation based on the consideration of the preservation of the Earth from research about space radiation.

Cosmic Radiation↗
PubMed2001

Radiation shielding of astronauts in interplanetary flights: the CREAM surveyor to Mars and the magnetic lens system for a spaceship.

The radiation absorbed by astronauts during interplanetary flights is mainly due to cosmic rays of solar origin (SCR). In the most powerful solar flares the dose absorbed in few hours can exceed that cumulated in one year of exposition to the galactic component of cosmic rays (GCR). At energies above the minimum one needed to cross the walls of the spaceship there are extrapolations and guesses, but no data, on the angular distribution of SCR's, an information that is necessary for establishing whatever defence strategy. It was therefore proposed of sending to Mars a measurement device, that should continuously collect data during the travel, and possibly also in the orbit around Mars and on the Mars surface. The device should identify the particle and privilege the completeness in the measurement of its parameters. In fact the high energy electrons travel at speed of the light and could be used in the and future dangerous proton component. Also the much less abundant but individually more dangerous ions should be identified. The device should indeed include a magnetic spectrometer and a high granularity range telescope, and a good time of flight measurement. ASI is supporting an assessment study of a possible mission of such a device on board of the 2005 probe to Mars. A parallel technical study is also in progress to define the workable techniques and the possible configurations of a system of magnetic lenses for protecting the crew of a spaceship.

Cosmic Radiation↗
PubMed1989

Biological effects of galactic radiation HZE particles in experiments on the orbital station Salyut 7.

Lettuce (Lactuca sativa) seeds were flown on-board the orbital station Salyut 7 for 66-457 days. It was found that a single heavy charged particle (HZE) hitting a seed only slightly affects the subsequent plant growth. However, morphological anomalies of varying type in primordial leaves and roots were observed that show good correlation with the location of the particle track. The most severe damage detected by light and an electron microscopy were "channels" in dry and soaked seeds. The appearance of "channels" seems to be related to the LET of the incident particle. This finding is of considerable importance for assessment of space flight radiation hazard.

Cosmic Radiation↗
PubMed1994

Space radiation dosimetry using bubble detectors.

Bubble detectors--a new development in radiation detection--has only recently been used for radiation measurements in space. One important characteristic of the bubble detector is that it operates on a phenomenon which bears considerable resemblance to biological response. Recent experimental results from irradiating bubble detectors with high-energy heavy ions point to the need to re-examine the methodology used for assessing space radiation and the relevance of conventional quantities such as dose equivalent for space dosimetry. It may be that biological hazard associated with the intensely ionizing events--associated with nuclear fragmentation but delivering relatively small dose equivalent--may be much more important than that associated with lightly ionizing events which comprise the bulk of the conventional radiation dose equivalent.

Canada↗
PubMed2004

Survey of current situation in radiation belt modeling.

The study of Earth's radiation belts is one of the oldest subjects in space physics. Despite the tremendous progress made in the last four decades, we still lack a complete understanding of the radiation belts in terms of their configurations, dynamics, and detailed physical accounts of their sources and sinks. The static nature of early empirical trapped radiation models, for examples, the NASA AP-8 and AE-8 models, renders those models inappropriate for predicting short-term radiation belt behaviors associated with geomagnetic storms and substorms. Due to incomplete data coverage, these models are also inaccurate at low altitudes (e.g., <1000 km) where many robotic and human space flights occur. The availability of radiation data from modern space missions and advancement in physical modeling and data management techniques have now allowed the development of new empirical and physical radiation belt models. In this paper, we will review the status of modern radiation belt modeling.

Atmosphere↗
PubMed1976

[Radiation burden from X-ray diagnosis and new technological developments (author's transl)].

Radiation exposure of the population is expressed nowadays in terms of genetically significant dose and its individual components are compared. The calculations necessary for the present considerations have been carried out. As a basis for evaluating radiation protection, the natural sources of radiation and therir variations are used. The dose of 110 mrem/a for the population of the Federal Republic is subject os considerable variations. Artificially produced radiation contributes a total of 60 mrem/a to the exposure. Of this, most is contributed by medical sources with 50 mrem/a, second is exposure due to atom bomb research. Other sources of radiation, such as occupational exposure, its use in research and technology, and use of nuclear technology, contribute little to total exposure, each producing about 1 mrem/a. The data provided is supported by numerical evidence.

Adolescent↗