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- Gustavsson, B, et al.
(författare)
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First observations of X-mode suppression of O-mode HF enhancements at 6300 angstrom
- 2009
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 36, s. L20102-
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Tidskriftsartikel (refereegranskat)abstract
- We present observations of radio induced optical emissions from a HAARP experiment with simultaneous transmission in X and O-mode. The additional transmission of X-mode with a frequency 700 kHz higher than the O-mode, reduces the enhancement of the 6300 A emission. This suggests that the wave-plasma process that energizes the electrons, which excites oxygen to the O(D-1) state, is closely connected to the excitation of upper-hybrid waves, whose onset and initial growth are reduced by additional X-mode pumping. Citation: Gustavsson, B., R. Newsome, T. B. Leyser, M. J. Kosch, L. Norin, M. McCarrick, T. Pedersen, and B. J. Watkins (2009), First observations of X-mode suppression of O-mode HF enhancements at 6300 angstrom, Geophys. Res. Lett., 36, L20102, doi:10.1029/2009GL039421.
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- Inzunza, J, et al.
(författare)
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Germfree status of mice obtained by embryo transfer in an isolator environment
- 2005
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Ingår i: Laboratory animals. - : SAGE Publications. - 0023-6772 .- 1758-1117. ; 39:4, s. 421-427
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Tidskriftsartikel (refereegranskat)abstract
- The technique of embryo transfer has been evaluated for the purpose of changing the mouse stocks to a germfree (GF) status. Our results show reproducible and quality-assured conversion of animals to those which are negative for the presence of microorganisms. Rapid and easy access to GF mice is advantageous for studies of selected microflora and their cross-talks with the host, when applying, e.g. genomic, proteomic and metabolic methodology. The study involved embryo transfer in an isolator environment, thereby allowing implantation of cleansed embryos into GF recipients under well-controlled conditions. The recipient females gave birth normally and took care of the offspring as if they were their own pups, thus enhancing the survival rate. Access to full technical resources required to maintain GF isolators are, however, a prerequisite. In this study, we used stainless steel isolators designed by Gustafsson (1959), on which a stereomicroscope was mounted to facilitate embryo transfer inside the isolator. The use of embryo transfer and isolator techniques will facilitate the availability of various mouse mutant models under different gnotobiotic conditions, GF, monoxenic or polyxenic animals, to enable comparison with conventional animals for physiological and pathophysiological studies.
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- Karlsson, Roger L., et al.
(författare)
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Statistical properties of ionospheric stimulated electromagnetic emissions
- 2006
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Ingår i: Annales Geophysicae. - 0992-7689 .- 1432-0576. ; 24:7, s. 1851-1859
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Tidskriftsartikel (refereegranskat)abstract
- We have analysed the statistical properties of the stimulated electromagnetic emissions (SEE) spectral features in the steady state, reached after a long period of continuous HF pumping of the ionosphere in experiments performed at the Sura ionospheric radio research facility in Russia. Using a digital filter bank method, we have been able to analyse complex valued signals within narrow frequency bands. Each of the SEE spectral features are thereby separated into a number of narrow spectral components. Statistical tests were performed for all these spectral components and the distributions of the spectral amplitudes and phases were evaluated. Also, a test for sinusoidal components was performed. These tests showed that all observed SEE features were indistinguishable from coloured Gaussian noise. The test results exclude that the SEE features can be the result of a single isolated coherent process, but does not rule out that there could be many statistically independent parametric wave-wave processes taking place simultaneously at various parts of the HF-pumped ionosphere, as long as the superposition from all these is incoherent. Furthermore, from the test results, we cannot exclude the possibility that the waveforms of some, or all, of the SEE features may be chaotic.
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