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At least 145 records · Page 8Linked to original sources
PubMed1996

Galactic cosmic ray flux simulation and prediction.

A dynamic galactic cosmic ray model is proposed to quantitatively describe the z=1-28 ions and electrons of E=10-10(5) MeV/nucleon and their particle flux variations around the Earth's orbit and beyond the Earth's magnetosphere due to diverse large-scale variations of solar activity factors. The variations of large-scale heliospheric magnetic fields and the galactic cosmic ray flux variation time delays relative to solar activity variations are simulated. The lag characteristics and sunspot number predictions having been determined in detail, the model can be used to predict galactic cosmic ray flux levels.

Cosmic Radiation↗
PubMed2004

An interplanetary shock traced by planetary auroral storms from the Sun to Saturn.

A relationship between solar activity and aurorae on Earth was postulated long before space probes directly detected plasma propagating outwards from the Sun. Violent solar eruption events trigger interplanetary shocks that compress Earth's magnetosphere, leading to increased energetic particle precipitation into the ionosphere and subsequent auroral storms. Monitoring shocks is now part of the 'Space Weather' forecast programme aimed at predicting solar-activity-related environmental hazards. The outer planets also experience aurorae, and here we report the discovery of a strong transient polar emission on Saturn, tentatively attributed to the passage of an interplanetary shock--and ultimately to a series of solar coronal mass ejection (CME) events. We could trace the shock-triggered events from Earth, where auroral storms were recorded, to Jupiter, where the auroral activity was strongly enhanced, and to Saturn, where it activated the unusual polar source. This establishes that shocks retain their properties and their ability to trigger planetary auroral activity throughout the Solar System. Our results also reveal differences in the planetary auroral responses on the passing shock, especially in their latitudinal and local time dependences.

Journal Article↗
PubMed1979

Radiation danger in prolonged manned space flights.

The author examines methods for prognosticating solar activity for several decades to determine optimum periods for prolonged space flight. The focus of the discussion is the presence of a change in magnetic polarity at the beginning of each 11-year solar cycle, resulting in a 22-year cycle. An historical review of solar cycles determined a super cycle of about 180 years. Using this data, it is determined that solar activity will be weak through the end of the 20th century.

Cosmic Radiation↗
PubMed1999

Probabilistic model for fluences and peak fluxes of solar energetic particles.

The model is intended for calculating the probability for solar energetic particles (SEP), i.e., protons and Z=2-28 ions, to have an effect on hardware and on biological and other objects in the space. The model describes the probability for the > or = 10 MeV/nucleon SEP fluences and peak fluxes to occur in the near-Earth space beyond the Earth magnetosphere under varying solar activity. The physical prerequisites of the model are as follows. 1. The occurrence of SEP is a probabilistic process. 2. The mean SEP occurrence frequency is a power-law function of solar activity (sunspot number). 3. The SEP size (taken to be the > or = 30 MeV proton fluence size) distribution is a power-law function within a 10(5)-10(11) proton/cm2 range. 4. The SEP event particle energy spectra are described by a common function whose parameters are distributed log-normally. 5. The SEP mean composition is energy-dependent and suffers fluctuations described by log-normal functions in separate events.

Cosmic Radiation↗
PubMedDate not supplied

[Cosmic rays as the main factor affecting solar variability on climatic and atmospheric parameters].

Analysis of experimental data demonstrates that cosmic ray enhancement stimulates an increase of atmospheric aerosols and cloudiness. The study of solar proton events (SPE) has shown that during SPE one can observe increase in aerosol density by 1.2-1.4 times at 12-18 km altitudes. Such variations of aerosol density can be detected on global scale. Aerosol variations cause changes in integral atmospheric transparency which during disturbed periods can reach 5-6%. The atmospheric integral transparency variations are not less during the solar cycle on account of galactic cosmic ray variations. Atmospheric transparency variations creating the so-called "grey filter" for solar radiation should lead to surface temperature variations. During the periods of low solar activity under the influence of enhanced galactic cosmic ray fluxes, the density of the "grey filter" should increase and cause a decrease in surface temperatures, correspondingly. In frame of the physical mechanism considered the connection between solar cycle durations and surface temperature variations can be explained. In addition, one can understand the physical reason for the "Little Ice Age" appearance during Maunder minimum of solar activity, 2400 years periodicity of climatic processes, strong influence of the decrease in main geomagnetic field intensity on the development of Ice Age and Global Cooling.

Atmosphere↗
PubMed1996

The Impact of Solar Variability on Climate

A general circulation model that simulated changes in solar irradiance and stratospheric ozone was used to investigate the response of the atmosphere to the 11-year solar activity cycle. At solar maximum, a warming of the summer stratosphere was found to strengthen easterly winds, which penetrated into the equatorial upper troposphere, causing poleward shifts in the positions of the subtropical westerly jets, broadening of the tropical Hadley circulations, and poleward shifts of the storm tracks. These effects are similar to, although generally smaller in magnitude than, those observed in nature. A simulation in which only solar irradiance was changed showed a much weaker response.

Journal Article↗
PubMed2003

Assessing exposure to cosmic radiation on board aircraft.

The assessment of exposure to cosmic radiation on board aircraft is one of the preoccupations of organizations responsible for radiation protection. The cosmic radiation particle flux increases with altitude and latitude and depends on the solar activity. The radiation exposure has been estimated on several airlines using transatlantic, Siberian and transequatorial routes on board subsonic and supersonic aircraft, to illustrate the effect of these parameters. Measurements have been obtained with a tissue equivalent proportional counter using the microdosimetric technique. Data have been collected at maximum solar activity in 1991-92 and at minimum in 1996-98. The lowest mean dose rate measured was 3 microSv/h during a Paris-Buenos Aires flight in 1991; the highest was 6.6 microSv/h during a Paris-Tokyo flight using a Siberian route and 9.7 microSv/h on Concorde in 1996-97. The mean quality factor is around 1.8. The corresponding annual effective dose, based on 700 hours of flight for subsonic aircraft and 300 hours for Concorde, can be estimated between 2 mSv for least-exposed routes and 5 mSv for more exposed routes.

Aircraft↗
PubMed2001

[Biphasic response of the human nervous system to geomagnetic storms studied by EEG].

In two subjects: a male phlegmatic, 56, and a female melancholic, 22, the EEG was recorded at resting. The EEG patterns were juxtaposed with the geomagnetic activity index Ar and the solar activity index SF, as well as between themselves. The results revealed qualitatively similar biphasic responses: a generalised diminishing of the EEG spatial synchronisation and, on the next day, a generalised augmentation of the phenomenon, as compared with a prolonged quiet period. A general unspecific stress response is supposed to underlie the aforementioned dynamics, whereas a reduced cortical tone during a magnetic storm and an enhanced one after its cessation correspond to the two phases observed. Specifics of responses in both subjects corresponded to their individual profiles of interhemisphere asymmetry.

Adult↗
PubMedDate not supplied

[Effect of natural factors on the occurrence of cardiovascular diseases].

The effect of natural environmental factors (indexes of solar activity, geomagnetic disturbances, as well as meteorologic parameters: air temperature and humidity, and atmospheric pressure) on the occurrence of cardiovascular diseases in Ukraine as a whole and in Kiev was analyzed. It is shown that, contrary to the stereotype, the yearly dynamics of cardiovascular diseases in 1980-1990 is in opposite phase with the solar activity cycle. Similar results were obtained for the monthly dynamics of cardiovascular diseases in the period from June 1991 to June 1993. The relative influence of five environmental factors (in complex) on the daily dynamics of cardiovascular diseases for the same period was calculated. The role of heliogeophysical factors becomes especially evident if the daily level of cardiovascular diseases within some month of the year is considered. This result may be interesting for medicinal practice and forecasting of cardiovascular diseases.

Cardiovascular Diseases↗
PubMed2000

Assessing exposure to cosmic radiation during long-haul flights.

The assessment of exposure to cosmic radiation on board aircraft is one of the concerns of organizations responsible for radiation protection. Cosmic-particle flux increases with altitude and latitude and depends on solar activity. To illustrate the effect of these parameters, exposure has been estimated on several airlines operating subsonic and supersonic aircraft on transatlantic, Siberian and transequatorial routes. Measurements have been made with a tissue-equivalent proportional counter using the microdosimetric technique. This type of system provides the absorbed dose, the ambient dose equivalent, the mean quality factor, and the dose distribution as a function of lineal energy. Data were collected at maximum solar activity in 1991-1992 and at minimum activity in 1996-1998. The lowest mean dose rate measured was 3 microSv h(-1) during a Paris-Buenos Aires flight in 1991. The highest rates were 6.6 microSv h(-1) during a Paris-Tokyo flight on a Siberian route and 9.7 microSv h(-1) on Concorde in 1996-1997. The mean quality factor is around 1.8. The corresponding annual effective dose, based on 700 h of flight for subsonic aircraft and 300 h for Concorde, can be estimated at between 2 mSv for the least-exposed routes and 5 mSv for the more-exposed routes.

Aviation↗
PubMed2002

Passive dosimetry aboard the Mir Orbital Station: internal measurements.

Passive radiation dosimeters were exposed aboard the Mir Orbital Station over a substantial portion of the solar cycle in order to measure the change in dose and dose equivalent rates as a function of time. During solar minimum, simultaneous measurements of the radiation environment throughout the habitable volume of the Mir were made using passive dosimeters in order to investigate the effect of localized shielding on dose and dose equivalent. The passive dosimeters consisted of a combination of thermoluminescent detectors to measure absorbed dose and CR-39 PNTDs to measure the linear energy transfer (LET) spectrum from charged particles of LET infinity H2O > or = 5 keV/micrometers. Results from the two detector types were then combined to yield mean total dose rate, mean dose equivalent rate, and average quality factor. Contrary to expectations, both dose and dose equivalent rates measured during May-October 1991 near solar maximum were higher than similar measurements carried out in 1996-1997 during solar minimum. The elevated dose and dose equivalent rates measured in 1991 were probably due to a combination of intense solar activity, including a large solar particle event on 9 June 1991, and the temporary trapped radiation belt created in the slot region by the solar particle event and ensuing magnetic storm of 24 March 1991. During solar minimum, mean dose and dose equivalent rates were found to vary by factors of 1.55 and 1.37, respectively, between different locations through the interior of Mir. More heavily shielded locations tended to yield lower total dose and dose equivalent rates, but higher average quality factor than did more lightly shielding locations. However, other factors such as changes in the immediate shielding environment surrounding a given detector location, changes in the orientation of the Mir relative to its velocity vector, and changes in the altitude of the station also contributed to the variation. Proton and neutron-induced target fragment secondaries, not primary galactic cosmic rays, were found to dominate the LET spectrum above 100 keV/micrometers. This indicates that in low earth orbit, trapped protons in the South Atlantic Anomaly are responsible for the major fraction of the total dose equivalent.

Atlantic Ocean↗
PubMed1995

Atmospheric deposition of cosmogenic 7Be and 137Cs from fallout of the Chernobyl accident.

Atmospheric (tropospheric) depositional fluxes of the naturally occurring 7Be of cosmogenic origin and 137Cs from fallout of the Chernobyl accident were measured over a 7-year period (January 1987-December 1993) at Thessaloniki, Greece (40 degrees 38' N, 22 degrees 58' E). The annual total deposition fluxes of 7Be varied between 854 Bq/m2 (1987) and 1242 Bq/m2 (1992), showing a minimum in the years 1988-89. The annual total deposition fluxes of 137Cs varied between 183 Bq/m2 (1987) and 16.4 Bq/m2 (1992), showing a significant decrease as expected for natural removal and radioactive decay and no new releases from nuclear facilities or weapons testing. The annual average total deposition velocity for 7Be was from 0.3 cm/s (1988) up to 0.8 cm/s (1991), while for 137Cs the corresponding values were much higher, hence 137Cs was associated with larger atmospheric particles. High 7Be concentrations in air were related to the very little solar activity (1987-88 and 1993-94), while low 7Be concentrations in air related to the high solar activity (1989-91). Maximum 137Cs concentrations in air were registered during the spring 1991 and 1992, reflecting some stratospheric inputs. An unusual highly elevated value of 137Cs concentration in air, reaching 0.25 mBq/m3, was observed during the summer 1990.

Air Pollutants, Radioactive↗
PubMed1980

The influence of the sun, moon, climate and economic conditions on crisis incidence.

Investigated the relationship between 2,344 cases of crisis incidence over a 1-year period (1976) and geophysical, climatic and seasonal conditions. Results revealed an intricate interactive effect between the variables of sex, nature of crisis, period of analysis, and environmental conditions. Males crisis became more likely, with downward economic trends or decreased solar activity. In contrast to female incidence of crisis, which peaked in spring, that of males peaked in autumn. Increased solar activity was related strongly to the incidence of crisis experienced by people who were retarded, abused drugs and were guilty of assault and/or rape. The waxing of the moon was related closely to cases of assault and/or rape, while retardates were influenced further by the moisture content in the air. Temporal considerations revealed a positive relationship between full moon and crisis incidence on alternate months only. Generally, the increased cloud cover, rainfall and temperature in summer, gave rise to more crisis consultations. Finally, geophysical, climatic and economic conditions also were seen to act in conjunction with each other to influence crisis incidence.

Adolescent↗
PubMed1993

Heliophysical activity and incidence variations of skin malignant melanoma in Czechoslovakia: a regional study.

Cyclic variations in the incidence of skin malignant melanoma during the years 1964-1985 in East Bohemia (excluding the districts of Pardubice and Svitavy), Czechoslovakia have been studied, as linear correlations with solar activity indexes have been revealed. The following statistical methods were applied: periodogram regression analysis, phase-correlation analysis, sigma-method and Student's t-test. The discretization of the data is on the basis of 1 year. Different cycles were found in the incidence variations (T = 7.5 years, T = 11.5 years, etc.), and this has been correlated with the variations of two heliophysical indexes (sigma, W) for the same time period. A few significant statistical relationships have been established with a time difference (lag-period) between the extremes of the data series; the incidence maxima follow the peaks of solar activity and appear about the minima of solar indexes, mainly.

Czechoslovakia↗
PubMed1992

Radiation situation determining the possibility of a manned flight to Mars and back.

Possible manned flights toward Mars are discussed from the viewpoint of radiation hazard. A standard situation is considered for the fast two times crossing of the Earth radiation belts. The flight to Mars is shown to be practically impossible without a special system of radiation shelters, because of the effect of penetrating galactic and solar radiations which are responsible for almost maximum permissible doses. But even in case there were radiation shelters on board the spacecraft their flights are undesirable in the periods of maximum and minimum solar activity. It would obviously be worthwhile to schedule Martian flights for intervals in between minima and maxima of 11-year cycles of solar activity when primary cosmic rays levels are considerable reduced and flare activity is not yet sufficiently high. It should be mentioned that it would not be easy to select such allowed intervals. Further studies of that aspect are discussed.

Astronauts↗
PubMed2002

Study of the dosimetric characteristics of cosmic radiation at civil aviation altitudes.

The dependence of the doses on solar activity for intermediate levels of the solar modulation parameter has been studied by means of simulations carried out by the Monte Carlo transport code FLUKA. The vertical cut-off rigidities investigated lie between 0.4 and 6.1 GV. The calculated results show that the linear dependence proposed in a previous work, for the effective dose rate as a function of the solar modulation parameter, can be considered as an acceptable approximation. In addition, some dosimetric characteristics of cosmic radiation and some properties of the dosemeters in use for monitoring in the cosmic ray environment have been analysed with a view to simplifying measurements. The depth-dose curves in the ICRU sphere and the response of a tissue-equivalent ionisation chamber have been determined by the FLUKA code for a number of cosmic ray spectra On the basis of the calculated results, it is concluded that a value of the depth. d, which would make the ambient dose equivalent a conservative predictor of the effective dose, cannot be specified for cosmic radiation. However, the operational quantity can be useful in order to verify the predictions of Monte Carlo calculations. It is demonstrated that a crude approximation of the ambient dose equivalent could be obtained by multiplying by 2 the absorbed dose measured by a tissue-equivalent ionisation chamber with wall thickness of 10 mm.

Aircraft↗
PubMed1965

Control over the cosmic radiation level during flight of space vehicles Vostok 3, Vostok 4, Vostok 5 and Vostok 6.

1. During the flights of the"Vostok"series of spaceships the radiation conditions in space were kept under operative control which comprised: a. The solar activity observation and forecasting of the solar flares followed by the appearance of proton fluxes in the near space. b. Probing the upper atmosphere with the help of balloon launchings at high altitudes. c. Direct measuring radiation level inside the "Vostok" spaceships. 2. The radiation dose received by the cosmonauts during the flights of the "Vostok" spaceships is given. Contributions of various components of cosmic radiation are considered. 3. The possibility of flights of the "Vostok" series of spaceships at high altitudes is evaluated.

Cosmic Radiation↗
PubMedDate not supplied

[Effects of solar and geomagnetic activity on the accuracy of laboratory methods in differentiation of Staphylococcus aureus and S. epidermidis].

The production of three obligatory enzymes (DNAse, RNAse, gelatinase) and of three facultative ones (lecithinase, a-hemolysin, plasma coagulase) by six strains of S. aureus, namely, 209, Smit, Wood 46, phagotype (3A, 3C, 71), (53, 75, 84, 85), and (52A, 79), was investigated, as was the activity of twenty taxonomic parameters in comparison with the cyclic changes of solar activity and magnetic field of the Earth. The follow-up period was two years, from 1988 through 1989. The measurements were taken once a month. Solar activity and geomagnetic field of the Earth were found to influence the autofluctuations of the parameters used to discriminate between S. aureus and S. epidermidis. The activity of formation of pathogenicity enzymes DNAse, RNAse, and gelatinase in the course of a year varied within a wide range: two- to ten-fold. Changes in the aggressive activity of staphylococci were characterized by a cyclic pattern with the cycle duration of about a year. Of the biochemical parameters the most labile were capacity to oxidize lactose, xylite, and D-melibiose, to hydrolyze urea, and the Voges-Proskauter test.

Deoxyribonucleases↗