5,841 research outputs found
An update on the correlation between the cosmic radiation intensity and the geomagnetic AA index
A statistical study between the cosmic ray intensity, as observed by a neutron monitor, and of the geomagnetic aa index, as representative of perturbations in the plasma and interplanetary magnetic field in the heliosphere, has been updated to specifically exclude time periods around the reversal of the solar magnetic field. The results of this study show a strong negative correlation for the period 1960 through 1968 with a correlation coefficient of approximately -0.86. However, there is essentially no correlation between the cosmic ray intensity and the aa index for the period 1972-1979 (i.e. correlation coefficient less than 0.16). These results would appear to support the theory of preferential particle propagation into the heliosphere vis the ecliptic during the period 1960-1968 and via the solar polar regions during 1972-1979
The use of the McIlwain L-parameter to estimate cosmic ray vertical cutoff rigidities for different epochs of the geomagnetic field
Secular changes in the geomagnetic field between 1955 and 1980 have been large enough to produce significant differences in both the verical cutoff rigidities and in the L-value for a specified position. A useful relationship employing the McIlwain L-parameter to estimate vertical cutoff rigidities has been derived for the twenty-five year period
Empirical model for the Earth's cosmic ray shadow at 400 KM: Prohibited cosmic ray access
The possibility to construct a unit sphere of access that describes the cosmic radiation allowed to an Earth-orbiting spacecraft is discussed. It is found that it is possible to model the occluded portion of the cosmic ray sphere of access as a circular projection with a diameter bounded by the satellite-Earth horizon. Maintaining tangency at the eastern edge of the spacecraft-Earth horizon, this optically occluded area is projected downward by an angle beta which is a function of the magnetic field inclination and cosmic ray arrival direction. This projected plane, corresponding to the forbidden area of cosmic ray access, is bounded by the spacecraft-Earth horizon in easterly directions, and is rotated around the vertical axis by an angle alpha from the eastern direction, where the angle alpha is a function of the offset dipole latitude of the spacecraft
North-south asymmetry in activity on the Sun and cosmic ray density gradients
The marked N-S asymmetry in solar activity (with predominant activity in the Sun's Northern Hemisphere) during the 1960's could certainly account for a S-pointing cosmic ray gradient. It is also clear from the data that the response to this change in solar activity asymmetry, and the related change in the perpendicular cosmic ray density gradient, is different for cosmic ray telescopes in the Earth's Northern and Southern Hemispheres. Northern Hemisphere detectors see a S-pointing gradient in the 60's and a N-pointing gradient after 1971, while Southern Hemisphere telescopes see a S-pointing gradient both before and after the reversal
Further development of a charged liquid colloid source for electrostatic propulsion Final report
Performance characteristics of charged liquid droplet electrostatic propulsion syste
An Improved Model for Relativistic Solar Proton Acceleration applied to the 2005 January 20 and Earlier Events
This paper presents results on modelling the ground level response of the
higher energy protons for the 2005 January 20 ground level enhancement (GLE).
This event, known as GLE 69, produced the highest intensity of relativistic
solar particles since the famous event on 1956 February 23. The location of
recent X-ray and gamma-ray emission (N14 W61) was near to Sun-Earth connecting
magnetic field lines, thus providing the opportunity to directly observe the
acceleration source from Earth. We restrict our analysis to protons of energy
greater than 450 MeV to avoid complications arising from transport processes
that can affect the propagation of low energy protons. In light of this revised
approach we have reinvestigated two previous GLEs: those of 2000 July 14 (GLE
59) and 2001 April 15 (GLE 60). Within the limitations of the spectral forms
employed, we find that from the peak (06:55 UT) to the decline (07:30 UT)
phases of GLE 69, neutron monitor observations from 450 MeV to 10 GeV are best
fitted by the Gallegos-Cruz & Perez-Peraza stochastic acceleration model. In
contrast, the Ellison & Ramaty spectra did not fit the neutron monitor
observations as well. This result suggests that for GLE 69, a stochastic
process cannot be discounted as a mechanism for relativistic particle
acceleration, particularly during the initial stages of this solar event. For
GLE 59 we find evidence that more than one acceleration mechanism was present,
consistent with both shock and stochastic acceleration processes dominating at
different times of the event. For GLE 60 we find that Ellison & Ramaty spectra
better represent the neutron monitor observations compared to stochastic
acceleration spectra. The results for GLEs 59 and 60 are in agreement with our
previous work.Comment: 42 pages, 10 figures, 10 tables, published in ApJ, August 200
Tandem Intramolecular Nicholas and Pauson-Khand Reactions for the Synthesis of Tricyclic Oxygen-Containing Heterocycles
Simple acyclic enynes can be easily converted into tricyclic ethers upon treatment with Co2(CO)8followed by Nicholas and Pauson−Khand reactions. Tricyclic [5,8,5]- and [5,7,5]-systems can be prepared in high overall yields in only seven synthetic steps
Carbon-Based Ocean Productivity and Phytoplankton Physiology from Space
Ocean biogeochemical and ecosystem processes are linked by net primary production (NPP) in the ocean\u27s surface layer, where inorganic carbon is fixed by photosynthetic processes. Determinations of NPP are necessarily a function of phytoplankton biomass and its physiological status, but the estimation of these two terms from space has remained an elusive target. Here we present new satellite ocean color observations of phytoplankton carbon (C) and chlorophyll (Chl) biomass and show that derived Chl:C ratios closely follow anticipated physiological dependencies on light, nutrients, and temperature. With this new information, global estimates of phytoplankton growth rates (mu) and carbon-based NPP are made for the first time. Compared to an earlier chlorophyll-based approach, our carbon-based values are considerably higher in tropical oceans, show greater seasonality at middle and high latitudes, and illustrate important differences in the formation and demise of regional algal blooms. This fusion of emerging concepts from the phycological and remote sensing disciplines has the potential to fundamentally change how we model and observe carbon cycling in the global oceans
Effect of religiosity/spirituality and sense of coherence on depression within a rural population in Greece: the Spili III project
Background: Recent research has addressed the hypothesis that religiosity/spirituality and sense of coherence buffer the negative effects of stress on numerous health issues. The aim of the current study was to further this work by exploring potential links between psycho-social factors such as religiosity/ spirituality and sense of coherence with depression.
Methods: A total of 220 subjects of the SPILI III cohort (1988-2012) attending a primary care setting in the town of Spili on rural Crete represented the target group. All participants underwent a standardized procedure. Validated questionnaires were used to evaluate sense of coherence, depression levels and religious and spiritual beliefs. A multiple linear regression analysis of the Beck Depression Inventory Scale (BDI) in relation to demographic characteristics, scores on the Royal Free Interview for Spiritual and Religious Beliefs scale (RFI-SRB) and Sense of Coherence scale (SOC) was used.
Results: A significant inverse association was found between BDI and RFI-SRB scale (B-coef=-0.6999, p<0.001), as well as among BDI and SOC scale (B-coef=-0.556, p<0.001).
Conclusions: The findings of the current observational study indicate that highly religious participants are less likely to score high in the depression scale. Furthermore, participants with high SOC scored significantly low in the BDI scale. Further research is required in order to explore the potential effect of SOC and religiosity/spirituality in mental health
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